TECHNICAL REPORTS SERIES No. 5 6

Pressure Vessel Codes:

Their Application to

Nuclear Reactor Systems

I V

} INTERNATIONAL ATOMIC ENERGY AGENCY,VIENNA, 1 9 6 6 j k

PRESSURE VESSEL CODES: THEIR APPLICATION TO NUCLEAR

REACTOR SYSTEMS

T h e fol lowing States are Members of the International Atomic Energy Agency:

A F G H A N I S T A N FEDERAL REPUBLIC OF NICARAGUA ALBANIA GERMANY NIGERIA ALGERIA GABON NORWAY ARGENTINA G H A N A PAKISTAN AUSTRALIA GREECE P A N A M A AUSTRIA G U A T E M A L A PARAGUAY BELGIUM H A I T I PERU BOLIVIA HOLY SEE PHILIPPINES BRAZIL HONDURAS POLAND BULGARIA HUNGARY PORTUGAL BURMA ICELAND ROMANIA BYELORUSSIAN SOVIET I N D I A SAUDI ARABIA

SOCIALIST REPUBLIC INDONESIA SENEGAL C A M B O D I A IRAN S O U T H AFRICA CAMEROON IRAQ SPAIN C A N A D A ISRAEL SUDAN

CEYLON I T A L Y SWEDEN

CHILE IVORY C O A S T SWITZERLAND

C H I N A J A M A I C A SYRIA

COLOMBIA JAPAN T H A I L A N D C O N G O , D E M O C R A T I C KENYA T U N I S I A

REPUBLIC OF REPUBLIC OF KOREA TURKEY COSTA RICA K U W A I T UKRAINIAN SOVIET SOCIALIST

CUBA LEBANON REPUBLIC

CYPRUS LIBERIA UNION OF SOVIET SOCIALIST

CZECHOSLOVAK SOCIALIST LIBYA REPUBLICS

REPUBLIC LUXEMBOURG U N I T E D ARAB REPUBLIC

DENMARK M A D A G A S C A R UNITED K I N G D O M OF GREAT

D O M I N I C A N REPUBLIC M A L I BRITAIN AND NORTHERN

ECUADOR M E X I C O IRELAND

EL SALVADOR M O N A C O UNITED STATES OF AMERICA

ETHIOPIA MOROCCO URUGUAY

F INLAND NETHERLANDS VENEZUELA

FRANCE ' NEW Z E A L A N D V I E T - N A M YUGOSLAVIA

T h e Agency's Statute was approved on 23 October 1956 by the Conference on the Statute of the

IAEA held at Uni ted Nations Headquarters, New York; it entered into force on 29 July 1957. The

Headquarters of the Agency are situated in V i e n n a . Its principal object ive is "to accelerate and enlarge

the contribution of a tomic energy to peace, health and prosperity throughout the world".

© I A E A , 1966

Permission to reproduce or translate the informat ion contained in this publication m a y b e obtained

by wri t ing to the Internat ional A tomic Energy Agency, Kärntner Ring 11 , V ienna I , Austria.

Printed by the IAEA in Austria

M a y 1966

TECHNICAL REPORTS SERIES No. 56

PRESSURE VESSEL CODES: THEIR APPLICATION

TO NUCLEAR REACTOR SYSTEMS

FINDINGS FROM A SURVEY BY THE INTERNATIONAL ATOMIC ENERGY AGENCY

INTERNATIONAL ATOMIC ENERGY AGENCY VIENNA, 1966

I n t e r n a t i o n a l A t o m i c E n e r g y A g e n c y . P r e s s u r e v e s s e l c o d e s ; t h e i r a p p l i c a t i o n to

n u c l e a r r e a c t o r s y s t e m s . F i n d i n g s f r o m a s u r v e y by t h e I n t e r n a t i o n a l A t o m i c E n e r g y A g e n c y . V ienna , t h e A g e n c y , 1966.

32 p . ( IAEA, T e c h n i c a l r e p o r t s s e r i e s no . 56)

6 2 1 . 0 3 9 . 5 3 6 . 2

P R E S S U R E V E S S E L CODES: T H E I R A P P L I C A T I O N T O N U C L E A R R E A C T O R S Y S T E M S , I A E A , V I E N N A , 1966

S T I / D O C / 10 /56

FOREWORD

A s u r v e y h a s b e e n m a d e by the I n t e r n a t i o n a l A t o m i c E n e r g y A g e n c y of how the p r o b l e m s of applying na t iona l p r e s s u r e v e s s e l codes to n u c l e a r r e a c t o r s y s t e m s have been t r e a t e d in those M e m b e r S ta tes that had p r e s s u r -i z e d r e a c t o r s in o p e r a t i o n o r u n d e r c o n s t r u c t i o n a t t h e beg inn ing of 1963. F i f t e e n a n s w e r s r e c e i v e d to an of f ic ia l inqui ry f o r m the bas i s of this r e p o r t , which a l so t akes into account some r ecen t l y published m a t e r i a l . The r e p o r t has been compi led by M r . R. Sk jö ldebrand of the Divis ion of Nuc lea r P o w e r and R e a c t o r s of the In t e rna t iona l Atomic E n e r g y Agency.

A l though the a n s w e r s to the i n q u i r y in s o m e c a s e s da te b a c k to 1963 and a l so r e f l e c t the diff icul ty of desc r ib ing local s i tuat ions in answer to s tan-d a r d ques t i ons , i t i s hoped that the r e p o r t will be of i n t e r e s t to r e a c t o r en-g i n e e r s , e s p e c i a l l y in t h o s e c o u n t r i e s in to which n u c l e a r p o w e r i s now to be i n t r o d u c e d .

The Agency i s g r a t e f u l to the G o v e r n m e n t s of the M e m b e r S ta tes which con t r ibu ted t h e i r e x p e r i e n c e to th i s r e p o r t by answer ing the inqui ry .

CONTENTS

I . INTRODUCTION 9

II . LAWS, REGULATIONS AND REGULATORY

STANDING O F CODES 12

III. SCOPE AND C O N T E N T O F NATIONAL CODES 13

IV. T H E A P P L I C A T I O N O F NATIONAL PRESSURE VESSEL

CODES TO NUCLEAR SYSTEMS 13

V. NEW NUCLEAR CODES AND CODE S U P P L E M E N T S 16

VI. MAJOR CONSIDERATIONS FOR NUCLEAR

PRESSURE VESSELS 17

Spec ia l r e q u i r e m e n t s due to r a d i a t i o n e m b r i t t l e m e n t of s t e e l s . . . 18

R e q u i r e m e n t s due to i n a c c e s s i b i l i t y f o r p e r i o d i c in spec t ions . . . 20

Addi t iona l r e q u i r e m e n t s 23

E x c e p t i o n s g r a n t e d f r o m ex i s t ing codes 23

VII. CONCLUSION 24

R E F E R E N C E S 25

ANNEX: NATIONAL REGULATIONS AND CODES AND THEIR ADMINISTRATION 27

I . INTRODUCTION

The des ign , c o n s t r u c t i o n and ma in tenance of n u c l e a r r e a c t o r p r e s s u r e s y s t e m s pose a n u m b e r of new p r o b l e m s in connec t ion with the app l i ca t ion of n o r m a l p r e s s u r e v e s s e l codes and r e g u l a t i o n s . In p a r t , t hese p r o b l e m s c o n c e r n new a s p e c t s of p r e s s u r e v e s s e l t e c h n i q u e s such as the v e r y l a r g e s i z e s of the p re sen t ly produced and designed r e a c t o r v e s s e l s , the high p r e s -s u r e s and l a r g e vo lumes , and thus the l a r g e s t o r e d ene rg i e s in the s y s t e m s . Of t en u n c o n v e n t i o n a l m a t e r i a l s and f a b r i c a t i o n t e c h n i q u e s a r e u s e d , e . g . m a t e r i a l s such as Z i r c a l o y , p r e s t r e s s e d c o n c r e t e o r m u l t i - l a y e r e d v e s s e l w a l l s . The m a i n p r o b l e m s , h o w e v e r , a r e : the v e s s e l s u n d e r g o s e r v i c e in high r a d i a t i o n f i e l d s , which a f f ec t the m a t e r i a l s and c a u s e t h e i r a c t i v a -t ion; they a r e i n a c c e s s i b l e f o r rou t ine i n s p e c t i o n s once they have been put in to o p e r a t i o n ; they con ta in v e r y l a r g e a m o u n t s of r a d i o a c t i v e m a t e r i a l s in ope ra t ion ; and t h e r e can be v e r y g r a v e consequences in the event of leakage o r f a i l u r e . F ina l ly , nuc l ea r r e a c t o r s a r e often sold in terna t ional ly , and it can s o m e t i m e s be v e r y d i f f icul t fo r a m a n u f a c t u r e r to unde r s t and and m e e t the r e q u i r e m e n t s of f o r e i g n c o d e s . T y p i c a l of t h e s e l a t t e r p r o b l e m s i s a s t a t e m e n t made at the Th i rd Geneva Confe rence by a Dutch m a n u f a c t u r -ing g r o u p [1] : "Not a l l c o u n t r i e s have r u l e s f o r n u c l e a r v e s s e l s , thus lengthy d i s c u s s i o n s with the au tho r i t i e s conce rned a r e r e q u i r e d to e s t a b l i s h a s e t of r u l e s . In the s e c o n d p l a c e , w h e r e one h a s to d e s i g n a v e s s e l t o m o r e than one code , conf l ic t ing r e q u i r e m e n t s have to be d i s c u s s e d be tween the a u t h o r i t i e s c o n c e r n e d . The c o n v e n t i o n a l c o d e s in m o s t c a s e s do not give s u f f i c i e n t i n f o r m a t i o n on the des ign r e q u i r e m e n t s of n u c l e a r v e s s e l s , s o a d d i t i o n a l , p r o v i s i o n a l r u l e s a r e g iven o r c a l c u l a t i o n m e t h o d s have to be a g r e e d upon and m u c h d e t a i l e d a n a l y s i s i s a s k e d f o r " .

P r e s s u r e v e s s e l codes can indeed be of c r u c i a l i m p o r t a n c e f o r the de-s ign and c o n s t r u c t i o n of n u c l e a r r e a c t o r v e s s e l s . F o r the s i z e s and design p r e s s u r e s now c o n s i d e r e d f o r b ig p o w e r s t a t i o n s in the 1000-MW r a n g e , a nat ional code i n t e r p r e t a t i o n o r ru l ing may not only s eve re ly affect the cost of the plant but a lso in fact make it technical ly unfeas ible to build and inspect a c e r t a i n r e a c t o r in one count ry while it may be poss ib le in another . F igu re 1 shows the s i ze r a n g e s f o r buil t and planned boi l ing and p r e s s u r i z e d l ight -w a t e r p o w e r r e a c t o r v e s s e l s .

As i s shown by r ecen t deve lopments , t h e s e b ig - s i ze v e s s e l s a r e ne -c e s s a r y to a c h i e v e e c o n o m i c c o m p e t i t i v e n e s s f o r n u c l e a r p o w e r . T h e da t a in T a b l e I a r e i l l u s t r a t i v e f o r the wide v a r i a t i o n s that a r e obta ined in a s i m p l e c a l c u l a t i o n of the w a l l t h i c k n e s s a s r e q u i r e d by v a r i o u s n a t i o n a l c o d e s f o r t y p i c a l m o d e r n p o w e r r e a c t o r v e s s e l s . T h e BWR in t h i s t a b l e r e f l e c t s des ign data fo r the Oys te r C r e e k plant and the PWR the Connect icut Yankee s ta t ion , both now under cons t ruc t ion .

T h e p r o b l e m s of a p p l y i n g p r e s s u r e v e s s e l c o d e s to n u c l e a r r e a c t o r s y s t e m s wil l be e n c o u n t e r e d m u c h m o r e of ten and on a l a r g e r s c a l e in the f u t u r e . It i s expected that by 1980 the ins ta l l ed nuc l ea r genera t ing capac i ty wi l l be m o r e than 200 000 MW(e), which would c o r r e s p o n d to at l e a s t s o m e 200 to 300 new n u c l e a r power plants being in opera t ion by that t i m e . F i f t y -n ine of t h e m a r e a l r e a d y f i r m l y p lanned o r u n d e r c o n s t r u c t i o n . Many of t h e s e r e a c t o r s wi l l be in deve lop ing c o u n t r i e s which do not have the l e v e l

9

FIG. 1. D i a m e t e r of l i gh t -wa te r reactor,vessels

of g e n e r a l t echno log ica l deve lopmen t that has e a s e d the p r o b l e m s of p r e s -s u r e v e s s e l d e s i g n and c o n s t r u c t i o n in , e . g . , t he Uni ted K i n g d o m o r the Un i t ed S t a t e s of A m e r i c a .

At the s a m e t i m e the v e r y r a p i d d e v e l o p m e n t in n u c l e a r r e a c t o r t e c h -nology wil l m a k e i t d i f f icu l t to adapt exis t ing nat ional codes through supple-m e n t s o r ca se ru l ings fo r nuc lea r r e a c t o r s y s t e m s o r to formula te new codes to c o v e r r e a c t o r s y s t e m app l i ca t ions in a g e n e r a l way. New codes should c o v e r the w ide ly d i f f e r e n t c a s e s of w a t e r - m o d e r a t e d and coo led r e a c t o r s on the one s ide and g a s - c o o l e d , g r a p h i t e - m o d e r a t e d r e a c t o r s on the o t h e r , a l l of which s y s t e m s have been and a re being built fo r nuc lear power s tat ions. Al l t h e s e s y s t e m s a r e in a s t age of rap id deve lopment , e . g . t owards i n t e r -na l n u c l e a r s u p e r h e a t i n g of the s t e a m in w a t e r - c o o l e d s y s t e m s and towards v e r y high exit t e m p e r a t u r e s of m o r e than 700°C of gas coolants . The coolant p a r a m e t e r s of the p r e s e n t advanced r e a c t o r concepts a r e such that new prob-l e m s of d e s i g n and m a n u f a c t u r é a r e r a i s e d a l s o f o r the m o r e convent iona l p a r t s of the r e a c t o r s t a t ion s y s t e m s . All the s a m e , the p r e s e n t genera t ion of r e a c t o r s wi l l m o s t p r o b a b l y be s u p e r s e d e d wi th in s o m e d e c a d e s by en -t i r e l y d i f f e r e n t t y p e s , such a s advanced c o n v e r t e r s o r s o d i u m - c o o l e d f a s t b r e e d e r s , which wi l l p l a c e new and s t i l l m o r e d i f f e r e n t r e q u i r e m e n t s on the p r e s s u r e v e s s e l s y s t e m s .

The p r o b l e m s p o s e d by the a p p l i c a t i o n of the m a n y d i f f e r e n t n a t i o n a l c o d e s have a l r e a d y in the p a s t b e e n s e v e r e and i t w a s s u g g e s t e d t h a t the I n t e r n a t i o n a l A tomic E n e r g y Agency make a s u r v e y of how p r e s s u r e v e s s e l

10

TABLE -I

SCHEMATIC CODE EXAMPLES FOR TYPICAL LIGHT-WATER REACTORS

BWR, Oys ter Creek Plant (515 MW(e)) PWR, Connect icut Yankee Plant (462 MW(e))

BWR PWR

Inner d iameter ( c m ) 5 4 1 3 9 1

Design pressure ( k g / c m 2 ) 88 176

M a t e r i a l , A S M E spec. S A - 3 0 2 - B S A - 3 0 2 - B

Coolant out let temperature ( ° C ) 285 308

W a l l thickness ( m m ) :

(a ) As ac tua l ly bui l t 181 270

(b) Designed to code of

Austra l ia 254 384

Belgium 242 352

Denmark 274 396

Germany 173 270

Norway 226 326

Sweden 194 336

USSR 210 303

USA ( A S M E V I I I ) 175 264

I N S T A 194

codes have been applied in those Member States with exper ience in the con-s t r u c t i o n of p r e s s u r i z e d r e a c t o r s y s t e m s . An inqui ry was sent out and by the middle of 1964 f i f teen answers had been rece ived . Some additional back-ground l i t e r a t u r e has been rev iewed and included, but the r e p o r t i s main ly b a s e d on t h e s e a n s w e r s , which m e a n s that the i n f o r m a t i o n in s o m e c a s e s da tes back to 1963. F u r t h e r , the a n s w e r s were ve ry d i f fe ren t in the scope they covered , and in the amount of detail they gave. In many cases the speci-f ic t e c h n i c a l e x a m p l e s have been t aken f r o m the l i t e r a t u r e to s u p p o r t the m o r e g e n e r a l c o n s i d e r a t i o n s r e f e r r e d to in the o f f i c i a l a n s w e r s to the Agency ' s inqu i ry . Both w a t e r - c o o l e d and m o d e r a t e d and gas -coo led r e a c -t o r s a r e covered by the a n s w e r s , i . e . both water p r e s s u r e v e s s e l s o r boi-l e r s and gas p r e s s u r e v e s s e l s . The a n s w e r s n a t u r a l l y a l so r e f l e c t l o c a l s i tuat ions and the difficulty of descr ib ing them in reply to a s tandard inquiry. The repor t thus cannot claim complete coverage. Never theless it is believed that the m a t e r i a l can give s o m e background f o r the work on code p r o b l e m s

11

now going on in m a n y c o u n t r i e s and tha t i t m a y be of s o m e a s s i s t a n c e in the c o u n t r i e s that a r e now planning the ins ta l la t ion of t he i r f i r s t power r e a c t o r s .

I I . L A W S , R E G U L A T I O N S AND R E G U L A T O R Y STANDING O F C O D E S

In m o s t c o u n t r i e s the d e s i g n , c o n s t r u c t i o n and i n s p e c t i o n of p r e s s u r e v e s s e l s in g e n e r a l a r e s u b j e c t to g o v e r n m e n t r e g u l a t i o n s , but the type of r e g u l a t o r y c o n t r o l v a r i e s w i t h i n v e r y wide l i m i t s . T h i s wi l l s o m e t i m e s have a b e a r i n g on how the r egu la t i ons and codes a r e applied to r e a c t o r s y s -t e m s , and the p e r t i n e n t f a c t s f o r each of the c o u n t r i e s which a n s w e r e d the A g e n c y ' s i n q u i r y have t h e r e f o r e been c o l l e c t e d in the Annex.

To i l l u s t r a t e the v e r y d i f f e ren t posi t ions in va r i ous count r ies , jus t some e x a m p l e s can be given h e r e . In Belgium a roya l d e c r e e const i tu tes the whole code and in India and J a p a n the codes a r e m i n i s t r y r egu la t ions , wr i t t en and i s s u e d by gove rnmen t d e p a r t m e n t s . On the o t h e r hand, in the United King-dom and in F r a n c e , the l a w s give only a m i n i m u m of guidance on t e c h n i c a l ques t ions , p lac ing a gene ra l r e spons ib i l i ty fo r sa fe ty on the o w n e r / o p e r a t o r of the p lan t . Most c o u n t r i e s take a posi t ion in between these e x t r e m e s with a l aw e s t a b l i s h i n g p r i n c i p l e s on ly , r e f e r r i n g d e t a i l e d p r o b l e m s of d e s i g n and c o n s t r u c t i o n to codes w r i t t e n by a t echnica l o rgan iza t ion . Thus in N o r -way the law e s t a b l i s h e s t h r e e manda to ry codes , the Dutch law gives the code r e g u l a t o r y s t and ing , while i n D e n m a r k and Sweden the codes have no l ega l s tanding p e r se but a r e in p r a c t i c e of f ic ia l and m a n d a t o r y as they have been adopted by the government depa r tmen t s that a r e by law responsib le for labour p r o t e c t i o n . In f e d e r a l un ions such a s A u s t r a l i a , Canada , G e r m a n y and the United S t a t e s of A m e r i c a the r e g u l a t o r y s tanding of the codes is de t e rmined by the s e p a r a t e s t a t e s o r p rov inces in the union, where mos t often the proce-d u r e of a s t a t e l aw e s t a b l i s h i n g a t e c h n i c a l c o d e h a s b e e n f o l l o w e d .

In a f ew c o u n t r i e s , e x p r e s s p r o v i s i o n i s m a d e f o r the a c c e p t a n c e of f o r e i g n c o d e s . Thus the A u s t r a l i a n Code CB1/1962 P a r t I I ,deal ing with un-f i r e d p r e s s u r e v e s s e l s , r e c o g n i z e s s o m e B r i t i s h and US n a t i o n a l s p e c i f i -c a t i o n s and c o d e s a s a c c e p t a b l e , a m o n g t h e m B r i t i s h S t a n d a r d s , L l o y d ' s R u l e s and Regu la t ions , and ASME 1 Codes . The Canad ian Code B51 s p e c i -f i e s the u s e of ASME Codes with s o m e a m e n d m e n t s .

The a d m i n i s t r a t i o n and e n f o r c e m e n t of the codes l ikewise v a r y g r ea t l y . Most coun t r i e s have inspec t ion organiza t ions , which may be par t of a govern-m e n t o r s t a t e d e p a r t m e n t ( A u s t r a l i a , C a n a d a , D e n m a r k , F r a n c e , I nd i a , J a p a n , N e t h e r l a n d s and Norway) , o r m a y be s e p a r a t e t e c h n i c a l o r g a n i z a -t ions recognized by a government o r s ta te depar tment (Germany and Sweden). In B e l g i u m r e c u r r i n g i n s p e c t i o n s a r e p e r f o r m e d by a u t h o r i z e d p r i v a t e o r -gan iza t ions . In the United S ta t e s of A m e r i c a in i t ia l inspect ion i s p e r f o r m e d by s t a t e i n s p e c t o r a t e s o r by c e r t i f i e d i n s p e c t o r s . In the Uni ted K ingdom the g e n e r a l e n f o r c e m e n t of the law is by the Min i s t ry of Labour (for nuc lea r i n s t a l l a t i o n s by the M i n i s t r y of P o w e r ) but d e t a i l e d i n s p e c t i o n s a r e m a d e e i t h e r by the p u r c h a s e r , by i n s u r a n c e i n s p e c t o r s , o r by o the r independent t e c h n i c a l i n spec t i on b o d i e s .

1 A S M E = A m e r i c a n Society of M e c h a n i c a l Engineers.

12

In s o m e c o u n t r i e s , e . g . Canada , an i n su rance would annul the r e q u i r e -m e n t f o r p e r i o d i c i n s p e c t i o n s by a u t h o r i t i e s , but the i n s u r a n c e c o m p a n i e s in s u c h c a s e s would p e r f o r m s i m i l a r i n s p e c t i o n s .

III. S C O P E AND C O N T E N T OF NATIONAL CODES

In T a b l e II the scope and conten t of the na t iona l r e g u l a t i o n s and codes have been s u m m a r i z e d as f a r as i s possible with the informat ion that i s avai l-a b l e . To p r o v i d e c o m p a r a t i v e m a t e r i a l , bo th r e g u l a t i o n and code s c o p e s have b e e n c o m b i n e d in the t a b l e wi thou t any a t t e m p t a t s e p a r a t i o n . I t i s obvious f r o m Table II tha t g r e a t d i f f e r e n c e s ex i s t between the coun t r i e s and t h a t t h i s would c a u s e p r o b l e m s f o r i n t e r n a t i o n a l d e l i v e r i e s e v e n f o r c o n -v e n t i o n a l v e s s e l s t h a t do not have the a d v a n c e d r e q u i r e m e n t s of n u c l e a r v e s s e l s .

F o r n u c l e a r app l i ca t ions i t can , fo r i n s t a n c e , be s e e n that many codes do not have m a t e r i a l spec i f i ca t ions f o r the m o d e r n low-a l loy , h igh - s t r eng th s t e e l s , which a r e the ones that mus t be used fo r big r e a c t o r ve s se l s . Fur ther , m a n y c o d e s do not g ive any d e s i g n s t r e s s v a l u e s even f o r the t e m p e r a t u r e r a n g e s of p r e s e n t w a t e r - c o o l e d r e a c t o r s , and v e r y few give v a l u e s in the h i g h e r t e m p e r a t u r e r a n g e of m o d e r n g a s - c o o l e d r e a c t o r s , f o r which c r e e p i s b e c o m i n g i m p o r t a n t . The given s t r e s s v a l u e s at e l e v a t e d t e m p e r a t u r e s v a r y c o n s i d e r a b l y . F e w c o d e s g ive s p e c i f i c a t i o n s f o r a l u m i n i u m and i t s a l l o y s , wh ich a r e e x t e n s i v e l y u s e d in r e s e a r c h r e a c t o r s y s t e m s .

M o s t of the c o d e s give e x t e n s i v e c o v e r a g e to we lded v e s s e l s , w e l d e r qua l i f i ca t i on , m a n u f a c t u r e by welding and i n spec t i on of we lds . The f o r m s of we ld ing c o n t r o l v a r y v e r y m u c h , r a n g i n g f r o m c o n t r o l of the w e l d e r ' s c a p a b i l i t y to s p e c i f i c a t i o n s f o r n o n - d e s t r u c t i v e t e s t i n g . R e q u i r e m e n t s of t e s t p la tes to be welded with longitudinal welds a r e quite common fo r quality c o n t r o l . R a d i o g r a p h y i s the only n o n - d e s t r u c t i v e t e s t i n g t echn ique wh ich i s c o m m o n l y r e c o g n i z e d , u l t r a s o n i c t e c h n i q u e s b e i n g m e n t i o n e d in s o m e c o d e s wi thout any d e t a i l e d s p e c i f i c a t i o n s .

An e x c e l l e n t s u r v e y of n a t i o n a l p r e s s u r e v e s s e l c o d e s , g iv ing m o r e d e t a i l e d i n f o r m a t i o n , h a s b e e n p u b l i s h e d by L a n c a s t e r [2].

IV. T H E A P P L I C A T I O N O F NATIONAL P R E S S U R E V E S S E L CODES T O N U C L E A R SYSTEMS

Al l the 15 M e m b e r S ta t e s that an swered the IAEA enquête s ta ted t h a t t h e n a t i o n a l p r e s s u r e v e s s e l r e g u l a t i o n s and codes had b e e n appl ied to the nu-c l e a r p r e s s u r e v e s s e l s y s t e m s bui l t in t h e s e c o u n t r i e s .

N i n e t e e n of the r e a c t o r s c o n c e r n e d a r e i m p o r t e d in to nine c o u n t r i e s . In s o m e of t h e s e c a s e s the a p p l i c a t i o n of the c o d e s w a s p a r t i c u l a r l y e a s y , a s p r o v i s i o n s e x i s t e d o r w e r e m a d e f o r t he a c c e p t a n c e of f o r e i g n c o d e s . A u s t r a l i a i s a p a r t i c u l a r l y c l e a r - c u t c a s e , a s the A u s t r a l i a n SAA2 Code m a k e s e x p r e s s p rov i s ions fo r the acceptance of the B r i t i s h Standard Specif i -c a t i o n s to which the HIFAR was des igned and bui l t in the Uni ted K ingdom.

2 SAA = Standards Association of Australia.

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TABLE U

S C O P E AND C O N T E N T S O F NATIONAL P R E S S U R E V E S S E L CODES AND REGULATIONS

Materials specifications Code design basis Welding Inspection procedures

Carbon Low alloy steel

High alloy steel

Non-ferrous metals

Values for high

temperatures

Tests and inspection of

mat «rials

Formula for min imum

Comple te stress

Allowable stress based on

Joint ef f ic iency

Welding approval

procedure

Tests of

welds

First Periodic steel

Low alloy steel

High alloy steel

Non-ferrous metals

Values for high

temperatures

Tests and inspection of

mat «rials wall thickness

analysis required

Yield strength

Ultimate strength

factor range

Welding approval

procedure

Tests of

welds inspection inspection

Australia Yes No Yes <Cu)

r e s Yes Yes Yes No Yes 0 . 4 1 - 1 . 0 Yes Yes r e s r e s

Belgium No No No No No Yes Yes No Yes < 0 . 7 No No Yes Yes

Canada ASME Code applies welding require-ments slightly modified in В 51

Denmark Yes No № No No No Yes No Yes 0 . 5 - 0 . 9 Yes Yes Yes No

France Yes Yes Yes Yes Yes Yes No Yes - Yes Yes Yes Yes

Germany Yes Yes Гез No Yes Yes Yes No Yes 0 . 8 - 1 . 0 Yes Yes Yes Yes

India - - - - - - - Yes Yes

INSTA Yes No No NO No r e s Yes No Yes 0 . 4 - 0 . 9 Yes Yes Yes No

Italy Yes Yes Yes Yes - - Yes No Y e s a Yes - - - -

Japan - - - - - - - • - Yes Yes Yes

Netherlands Yes Yes No No Yes - Yes No Yes Yes Yes Yes -

Norway Yes No No Yes No Yes Yes No Yes 0 . 5 - 0 . 9 Yes Yes Yes Yes

Sweden Yes Yes Yes No Yes No Yes No Yes 0 . 6 - 0 . 9 Yes Yes r e s Yes

UK - No Yes Yes No - - - - -

British Stand. 3915 Yes r e s No No Yes No Yes Yes Yes Yes 0 . 9 5 - 1 . 0 Yes Yes r e s No

USA ASME II , VIU and IX Yes Yes Ге$ Yes Yes Yes Yes No Yes Yes 0 . 4 5 - 1 . 0 Yes Yes Yes No

ASME III Yes Yes Yes Yes Yes Yes No Yes Yes Yes 1 .0 Yes Yes Yes No

USSR Yes Yes Yes Yes Yes No Yes No Yes 0 . 7 - 1 . 0 Yes Yes Yes No

- Information not available. 4 The proposed new code will use yie ld strength.

In D e n m a r k B r i t i s h and A m e r i c a n codes w e r e accep ted f o r the r e a c t o r s in o p e r a t i o n a t the R i s ^ R e s e a r c h E s t a b l i s h m e n t and in G r e e n l a n d , a l though the D a n i s h A t o m i c E n e r g y C o m m i s s i o n m a d e s o m e s p é c i a l add i t i ona l r e - ' q u i r e m e n t s . In G e r m a n y , w h e r e in g e n e r a l the n a t i o n a l c o d e s have b e e n app l i ed , f o r e i g n c o d e s have b e e n a c c e p t e d in s o m e s p e c i f i c s e c t o r s , e . g . r e g a r d i n g s p e c i a l d e s i g n s .

Some quite s e v e r e d i f f i cu l t i e s of a g e n e r a l n a t u r e have in m a n y c a s e s b e e n e n c o u n t e r e d in app ly ing n a t i o n a l c o d e s to r e a c t o r s y s t e m s . T h i s in m a n y c a s e s s t e m s f r o m the f ac t that the loca l codes a r e old and do not r e -f l e c t the t e c h n i c a l d e v e l o p m e n t tha t ha s t aken p l ace in the des ign and con-s t r u c t i o n of big p r e s s u r e v e s s e l s . S o m e t i m e s t h i s r e s u l t s in the na t iona l codes be ing too s t r i c t , e . g . in not r ecogn iz ing the high s t r e n g t h of m o d e r n p r e s s u r e v e s s e l s t e e l s , and s o m e t i m e s they a r e e n t i r e l y inadequate in that they do not cove r m o d e r n types of cons t ruc t ion of high p r e s s u r e , high power u n i t s . The m e r e s i z e s and w a l l t h i c k n e s s e s of r e a c t o r v e s s e l s i n m a n y c a s e s go f a r beyond ex i s t i ng p r a c t i c e s and have brought new r e q u i r e m e n t s beyond those of exis t ing codes . It should a lso be noted that somet imes codes which a r e not t r u l y a p p r o p r i a t e have to be appl ied . In India , f o r e x a m p l e , no code f o r un f i r ed p r e s s u r e v e s s e l s , under which r e a c t o r v e s s e l s arid s y s -t e m s a r e n o r m a l l y t r e a t e d , h a s e x i s t e d . The T a r a p u r BWB plan t shou ld , a s a s t e a m gene ra t i ng uni t , be des igned and m a n u f a c t u r e d accord ing to the r u l e s of the Indian B o i l e r Regu la t ions , which in many a s p e c t s would not be a p p l i c a b l e , a s the r e a c t o r p l an t n a t u r a l l y i s v e r y d i f f e r e n t f r o m any con -v e n t i o n a l b o i l e r .

F r o m the United Sta tes of A m e r i c a i t was pointed out that one m a j o r prob-l e m in applying s t r i ngen t codes to n u c l e a r v e s s e l s has been that of obtaining c l o s e a d h e r e n c e of a l l m a n u f a c t u r e r s and v e s s e l i n s p e c t o r s to the r e q u i r e -m e n t s of the codes in o r d e r to avoid de lays when such r e q u i r e m e n t s a r e en-fo rced . S imi l a r d i f f icu l t ies have indeed been exper ienced in many count r ies , as delays and r e j ec t i ons in n u c l e a r plant de l ive r i e s bea r wi tness .

In addi t ion to t h e s e m o r e g e n e r a l p r o b l e m s which would be s i m i l a r f o r both big convent ional un i t s and n u c l e a r v e s s e l s , t h e r e a r e some m a j o r ones wh ich d e r i v e f r o m the s p e c i a l c h a r a c t e r i s t i c s of n u c l e a r r e a c t o r s . The compe tence to deal with these p r o b l e m s has n o r m a l l y been developed within n a t i o n a l a t o m i c e n e r g y a u t h o r i t i e s , which have been c h a r g e d wi th the n a -t ional n u c l e a r power development p r o g r a m m e s . Often these author i t ies have a l so been given a s a f e t y con t ro l funct ion , which in o t h e r s i s handled by spe -c ia l a tomic e n e r g y con t ro l b o a r d s o r r e a c t o r sa fe ty c o m m i t t e e s . A r e a c t o r s a f e t y c o m m i t t e e m a y s o m e t i m e s be only a d v i s o r y , e . g . to a g o v e r n m e n t d e p a r t m e n t o r an a tomic e n e r g y au thor i ty o rgan iza t ion . In o the r i n s t ances the e x e r c i s e of the s a f e t y c o n t r o l func t ion by a con t ro l board o r d i r ec t l y by a government depa r tmen t will have a defini te regu la to ry c h a r a c t e r . P r e s s u r e v e s s e l s a f e t y i s u sua l ly c o n s i d e r e d as p a r t of n u c l e a r sa fe ty under this con-t r o l funct ion and i t i s thus i n t e r e s t i n g to s tudy how th is i s c o r r e l a t e d to the a d m i n i s t r a t i o n of p r e s s u r e v e s s e l c o d e s . P r o c e d u r e s and p r a c t i c e s v a r y v e r y m u c h , a s can be s e e n f r o m the fol lowing e x a m p l e s .

In Canada the r egu la to ry cont ro l over all nuc lea r r e a c t o r s i s the respon-s ib i l i ty of the A tomic E n e r g y Con t ro l B o a r d , which l i c e n s e s a r e a c t o r only a f t e r a t h o r o u g h r e v i e w of i t s s a f e t y . T h i s B o a r d s e e k s the adv ice of ap-p r o p r i a t e p r o v i n c i a l a u t h o r i t i e s r e g a r d i n g b o i l e r s and p r e s s u r e v e s s e l s .

15

J a p a n app l i e s i t s n o r m a l codes to r e s e a r c h r e a c t o r s but not to p o w e r r e a c t o r s , which a r e i n s t e a d s u b j e c t t o a p p r o v a l of t he M i n i s t r y of T r a d e and I n d u s t r y , in a c c o r d a n c e wi th a s p e c i a l r e g u l a t i o n f o r p o w e r r e a c t o r f a c i l i t i e s .

It i s i n t e r e s t i n g to no te tha t in s o m e c o u n t r i e s an a c t m a y p r e s c r i b e n u c l e a r l i cens ing p r o c e d u r e s that tend to give codes a r egu la to ry effect they do not o t h e r w i s e have . A c a s e in point i s the N u c l e a r In s t a l l a t i ons Act of 1965 in the United Kingdom.

Na tu ra l l y , i n t e rven t ion by n u c l e a r e n e r g y au tho r i t i e s o r cont ro l bodies to deviate f r o m usua l code p r a c t i c e s in n u c l e a r plant l icens ing has occu r r ed to the g r e a t e s t ex t en t in c o u n t r i e s w h e r e the p r o b l e m s of apply ing the n a -t ional code have been m o s t s e v e r e . One example is India, where the Atomic E n e r g y Act p rov ides for the poss ibi l i ty of supersed ing the Boi ler Regulations in r e l a t i o n to any f a c i l i t i e s owned by the C e n t r a l G o v e r n m e n t and engaged in c a r r y i n g out the p u r p o s e s of the A tomic E n e r g y A c t . D i f f i c u l t i e s w e r e encounte red with the appl icat ion of the Indian Boi le r Regulations to the T a r a -p u r p lant which i s be ing i m p o r t e d f r o m the Uni ted S ta t e s of A m e r i c a . S e v e r a l e x e m p t i o n s to t h e s e r e g u l a t i o n s would have to be made c o n c e r n i n g m a t e r i a l spec i f i ca t ions , weld f ac to r , gene ra l design, e t c . , and it is possible tha t an ASME code wi l l be adopted f o r th i s plant i n s t e a d . It i s thought pos -s ib le that with th is background an independent i n spec to ra t e will be e s t ab -l i shed u n d e r the Indian D e p a r t m e n t of Atomic E n e r g y , and a l so that an ap-p r o p r i a t e code wi l l be d r a f t e d f o r the gu idance of t h i s i n s p e c t o r a t e . I t i s quite probable that th is i s a solution to the problem of old or inadequate codes, to which r e c o u r s e will be taken in many count r ies as the f i r s t power r e a c t o r s a r e built .

V. NEW NUCLEAR CODES AND CODE SUPPLEMENTS

In m a n y c o u n t r i e s the p r e s s u r e v e s s e l code w r i t i n g bod ie s r e c o g n i z e the need to update o r r e - w r i t e the codes so that they s p e c i f i c a l l y cove r nu-c l e a r p r e s s u r e s y s t e m s . In the United S ta tes of A m e r i c a the ASME B o i l e r and P r e s s u r e V e s s e l Codes w e r e s u p p l e m e n t e d by s p e c i a l n u c l e a r r e a c t o r c a s e i n t e r p r e t a t i o n s [3] , the e a r l i e s t of which d a t e s back to 1959. In 1964 a new Sec t ion III " N u c l e a r V e s s e l s " of the ASME code was pub l i shed . The " P r o v i s i o n a l R e q u i r e m e n t s f o r the Design, Manufac ture and Tes t ing of Land-based N u c l e a r I n s t a l l a t i ons " , publ ished by L loyd ' s R e g i s t e r of Shipping 1960 [4], has been used in the United Kingdom, where the B r i t i s h Standards Inst i -tu t ion p u b l i s h e d B . S . 3915 " S p e c i f i c a t i o n f o r C a r b o n and Low Alloy S tee l P r e s s u r e V e s s e l s f o r P r i m a r y C i r c u i t s of N u c l e a r R e a c t o r s " in 1965. In G e r m a n y i t i s p lanned to amend the s t e a m bo i l e r and p r e s s u r e v e s s e l codes by s u p p l e m e n t s to the "AD M e r k b l ä t t e r " . A s e r i e s of a m e n d m e n t s to the e x i s t i n g c o d e s to c o v e r n u c l e a r c a s e s a r e a l s o p l anned in Sweden .

The ASME Sect ion III, N u c l e a r V e s s e l s , Code [5] m e r i t s spec ia l a t ten-t ion. It has been d i s c u s s e d m o r e ful ly by, among o t h e r s , Gaines and P o r s e [6] and thus only some of the m a j o r f e a t u r e s will be pointed out here to se rve f o r c o m p a r i s o n wi th s o m e of the r e q u i r e m e n t s r a i s e d f o r n u c l e a r v e s s e l s in o t h e r c o u n t r i e s . The ASME Sec t ion III Code i n t r o d u c e s a new concep t

16

of des ign c o m p a r e d to the e a r l i e r Sec t ions I and VIII. The des ign c r i t e r i a a r e d i f f e r e n t in the fo l lowing r e s p e c t s [7] :

"(a) Section III u s e s the m a x i m u m s h e a r s t r e s s (Tresca) theory of fa i lure ins tead of the m a x i m u m s t r e s s theory .

(b) Sect ion III r e q u i r e s the de ta i led ca lcu la t ion and c l a s s i f i c a t i on of all s t r e s s e s and the app l i ca t i on of d i f f e r e n t s t r e s s l i m i t s to d i f f e r e n t c l a s s e s of s t r e s s , w h e r e a s S e c t i o n s I and VIII g ive f o r m u l a s f o r m i n i m u m a l lowab le w a l l t h i c k n e s s .

(c) Sec t ion III r e q u i r e s the c a l c u l a t i o n of t h e r m a l s t r e s s e s and g ives a l lowab le v a l u e s f o r t h e m .

(d) Sect ion III c o n s i d e r s the poss ib i l i ty of fat igue fa i lu re and gives ru les f o r i t s p r e v e n t i o n . "

B e c a u s e of the c o m p l e t e s t r e s s a n a l y s i s t h a t i t r e q u i r e s , S e c t i o n III a l lows lower sa fe ty f a c t o r s . V e s s e l s designed to this code thus show savings in m a t e r i a l c o m p a r e d to those des igned to the o lde r code sec t ions . Ma te r i a l sav ings of 16% f o r a PWR r e a c t o r v e s s e l and 25% f o r a BWR r e a c t o r v e s s e l have been quoted [6].

Sec t ion III a l so r e q u i r e s m o r e ex t ens ive t e s t i ng of the m a t e r i a l s used , and r e c o m m e n d s that the i n c r e a s e in the b r i t t l e f r a c t u r e t r a n s i t i o n t e m p e r a -t u r e due to r a d i a t i o n d a m a g e , be checked pe r i od i ca l l y by m e a n s of s u r v e i l -lance spec imens i r r a d i a t e d in the r e a c t o r , a l so cons ider ing combined effects of f a b r i c a t i o n , s t r e s s , and neu t ron e x p o s u r e . R e q u i r e m e n t s on f ab r i ca t ion and i n s p e c t i o n a r e f ina l ly m o r e r e s t r i c t i v e in Sec t ion III than in the e a r l i e r code sec t ions , r e f l ec t ing the p r a c t i c e s that have been developed in the Amer i -can indus t ry f o r the manufac tu re of nuc lea r v e s s e l s .

The new ASME Sect ion III Code thus a i m s at a tho rough a n a l y s i s of the des igns and knowledge of the comple ted v e s s e l s , giving ins tead cons ide rab le s a v i n g s in m a t e r i a l and f a b r i c a t i o n . Th i s t r end to r e p l a c e l a r g e f a c t o r s of s a f e t y with c a r e f u l and sound eng inee r ing i s s ign i f i can t . The s a m e concept i s , f o r example , the b a s i s f o r the new B r i t i s h S t a n d a r d , and f o r a new code s u p p l e m e n t f o r n u c l e a r c a s e s be ing d r a f t e d in the N e t h e r l a n d s wh ich wi l l have e v e n h i g h e r d e s i g n s t r e s s v a l u e s t h a n ASME Sec t ion III.

VI . M A J O R C O N S I D E R A T I O N S F O R N U C L E A R P R E S S U R E V E S S E L S

Some m a j o r g e n e r a l c o n s i d e r a t i o n s c o n c e r n i n g the s p e c i a l c h a r a c t e r -i s t i c s of r e a c t o r s y s t e m s have been the b a s i s f o r s p e c i a l r e q u i r e m e n t s f o r n u c l e a r v e s s e l s in m o s t of the c o u n t r i e s c o n c e r n e d . They a r e a s fo l lows :

(a) F a s t neut ron i r r a d i a t i o n will cause an i n c r e a s e in the br i t t le f r a c t u r e t r a n s i t i o n t e m p e r a t u r e in s t ee l . The exposure range needed fo r this e f fec t to become s ignif icant i s one which can be reached in the walls of a n u c l e a r r e a c t o r p r e s s u r e v e s s e l du r ing i t s p r o j e c t e d l i f e t i m e .

(b) Owing to r a d i o a c t i v i t y , con t a ined in both fue l and coo lan t and in -duced in v e s s e l w a l l s , i t i s o f t en i m p o s s i b l e o r e x t r e m e l y d i f f icu l t to p e r f o r m the p e r i o d i c rou t ine ( e . g . annual ) i n s p e c t i o n s tha t a r e r e q u i r e d by m o s t p r e s s u r e v e s s e l r e g u l a t i o n s o r c o d e s .

17

T h e e f f e c t i v e c o n t a i n m e n t of l a r g e a m o u n t s of r a d i o a c t i v e m a t e r i a l i s one m a j o r c o n c e r n spec i f i ed by, among o t h e r s , D e n m a r k , G e r m a n y , Japan and the Uni ted S t a t e s of A m e r i c a , w h e r e n u c l e a r v e s s e l s p r e v i o u s l y w e r e

- c l a s s i f i ed as " v e s s e l s containing le thal subs t ances" fo r design, cons t ruc t ion and i n s p e c t i o n a c c o r d i n g to the ASME Sect ion VIII Code . The s a m e m a j o r c o n s i d e r a t i o n i s a l s o r e f l e c t e d by L l o y d ' s " P r o v i s i o n a l R e q u i r e m e n t s " [4] and [8] .

In addition to these cons ide ra t ions , which applied to mos t of the answer s r e c e i v e d , t h e r m a l s t r e s s e s in the walls due to changing opera t ing conditions ( G e r m a n y and USSR [9] ) and to r ad ia t ion hea t ing of the wal l m a t e r i a l (Ge r -m a n y , Sweden and USSR [9]^) have been r e p o r t e d a s a m a j o r c o n c e r n .

As a r e s u l t of t hese cons ide r a t i ons , both the new ASME Section III Code and L l o y d ' s " P r o v i s i o n a l R e q u i r e m e n t s " r e c o g n i z e the need to d i s t i n g u i s h b e t w e e n d i f f e r e n t c l a s s e s of v e s s e l s in a n u c l e a r p l an t s y s t e m . L l o y d ' s t h u s de f ine s C a t e g o r y A v e s s e l s as those that conta in r ad ioac t ive m a t e r i a l , a r e sub jec ted to h igh- leve l neu t ron i r r ad i a t i on and a r e inaccess ib l e for p e r i -o d i c m a i n t e n a n c e and i n s p e c t i o n . C a t e g o r y В a r e v e s s e l s w h i c h c o n t a i n r a d i o a c t i v e m a t e r i a l s in s e r v i c e but c a n be m a d e a v a i l a b l e f o r p e r i o d i c ma in tenance and inspec t ion dur ing shut -downs . Category С covers the p a r t s of the s y s t e m tha t a r e to func t ion as n o r m a l s e v e r e - d u t y p r e s s u r e v e s s e l s (L loyd ' s n o r m a l C l a s s I). E m e r g e n c y s t e e l con ta inment v e s s e l s f a l l u n d e r C a t e g o r y D . T h e ASME Sec t i on III , C l a s s A, would c o r r e s p o n d r o u g h l y to L l o y d ' s C a t e g o r y A and B , C l a s s В to C a t e g o r y D, and C l a s s С to C a t e -gory C. B . S . 3915 s i m i l a r l y dis t inguishes between two ca tegor ies of ve s se l s in nuc lea r s y s t e m s .

In the a n s w e r s r e c e i v e d to the Agency i n q u i r y , no d i s t inc t ion has gen-e r a l l y b e e n m a d e b e t w e e n any s u c h c a t e g o r i e s of n u c l e a r s y s t e m c o m p o -n e n t s . In the t e x t of t h i s r e p o r t , the only d i s t i n c t i o n t h a t i s m a d e i s thus be tween the r e a c t o r v e s s e l i t se l f and the n u c l e a r p r e s s u r e v e s s e l s y s t e m s , which would c o r r e s p o n d to ASME C l a s s A.

Special requirements due to radiation embrittlement of steels

The g e n e r a l c o n s i d e r a t i o n s above a l s o l e a d to s o m e g e n e r a l r e q u i r e -m e n t s quoted in many of the a n s w e r s to the IAEA inqu i ry . The p r o c e s s of r ad ia t ion e m b r i t t l e m e n t of s t ee l inf luences the choice of m a t e r i a l , the allow-able o p e r a t i n g condi t ions of the v e s s e l and i t s o p e r a t i o n a l l i f e t i m e . M a j o r t e s t i n g p r o g r a m m e s of i r r a d i a t e d t e s t s p e c i m e n s have b e e n p e r f o r m e d to e n s u r e tha t the p r e s s u r e v e s s e l s t e e l s u sed a r e wel l known e x p e r i m e n t a l l y ( e . g . I t a ly , N e t h e r l a n d s , Sweden, USA [6] ).

In many c o u n t r i e s i r r a d i a t i o n of r e a c t o r v e s s e l s t e e l s p e c i m e n s ins ide the r e a c t o r d u r i n g i t s o p e r a t i o n a l l i f e t i m e i s a l s o r e q u i r e d ( e . g . in G e r -many , I ta ly, Sweden, UK) o r r ecommended (by the USA in ASME Section III). V e r y e x t e n s i v e i r r a d i a t i o n p r o g r a m m e s f o r i n v e s t i g a t i o n s on s u r v e i l l a n c e s p e c i m e n s of the r e a c t o r v e s s e l m a t e r i a l have been r e p o r t e d by the United Kingdom and the United S ta tes of A m e r i c a [10] where the t e s t s include c o r -r o s i o n , impac t and t ens i l e s t r e n g t h on s a m p l e s f r o m the v e s s e l plate as well a s weld m e t a l and f o r g e d m a t e r i a l s . S a m p l e s a r e r e m o v e d and t e s t e d at p l a n n e d i n t e r v a l s d u r i n g the who le l i f e t i m e of the r e a c t o r v e s s e l . T h i s ,

18

however , a l so b r ings out the diff iculty in in te rp re t ing i r r ad ia t ion tes t resu l t s . E m b r i t t l e m e n t i s no t only a r e s u l t of f a s t n e u t r o n i r r a d i a t i o n but a l s o of n o r m a l ageing, s t r a i n ageing, inf luence of h e a t - a f f e c t e d zones in the neigh-bourhood of w e l d s , e t c . , which m a y c a u s e equal ly l a r g e o r l a r g e r changes in the t r a n s i t i o n t e m p e r a t u r e and about which , of c o u r s e , i r r a d i a t i o n t e s t s p e c i m e n s give no i n f o r m a t i o n . F u r t h e r , f o r r a d i a t i o n - i n d u c e d e m b r i t t l e -m e n t p r e v i o u s h e a t t r e a t m e n t of the m a t e r i a l , the imp ing ing neu t ron s p e c -t r u m and the i r r a d i a t i o n t e m p e r a t u r e a r e i m p o r t a n t p a r a m e t e r s that should be the s a m e fo r the t e s t spec imen as for the v e s s e l wall m a t e r i a l about which they a r e to give i n f o r m a t i o n . D o s e - r a t e e f f e c t s have a l so been r e p o r t e d but r e s u l t s a r e not cons i s t en t . The n o r m a l and min ia tu re Charpy Y-notch spec i -m e n t e s t s , n o r m a l l y used in such app l ica t ions , make it poss ib le to c o m p a r e the i r r a d i a t i o n behav iou r of d i f f e r e n t s t e e l s but do not give enough i n f o r m a -tion f o r a thorough eva lua t ion on an absolu te s c a l e of , f o r e x a m p l e , the ac -tual behav iour of a r e a c t o r v e s s e l under i r r a d i a t i o n , the sui tabi l i ty of a c e r -t a in s t e e l , the l i f e t i m e tha t can be s a f e l y e s t i m a t e d f o r a v e s s e l , o r m i n i -m u m s a f e work ing t e m p e r a t u r e s .

The ques t ion of how to eva lua te the su i t ab i l i t y of v e s s e l s t e e l s to m e e t r e a c t o r v e s s e l o p e r a t i n g condi t ions h a s been a p p r o a c h e d in d i f f e r e n t ways . In Sweden, fo r example , i t i s sugges ted that the i s o t h e r m a l Rober tson c r a c k -a r r e s t t e m p e r a t u r e t e s t be used as a b a s i s ; tha t i s , if the c r a c k a r r e s t t e m p e r a t u r e f o r i r r a d i a t e d s p e c i m e n s i s found to be v e r y m u c h l o w e r than the lowes t t e m p e r a t u r e a t which the v e s s e l wil l be p r e s s u r i z e d , then t h e r e i s a l a r g e s a f e t y m a r g i n and the s t e e l i s adequa te [11] .

A l s o the p r o b l e m s of l i f e t i m e and o p e r a t i o n a l l i m i t a t i o n s h a v e b e e n approached in s e v e r a l d i f f e r e n t ways and so f a r no c l e a r common p r a c t i c e s have b e e n d e v e l o p e d . N o r m a l l y , s h i e l d s a r e u s e d to r e d u c e v e s s e l - w a l l e x p o s u r e ; in J a p a n , f o r e x a m p l e , such sh i e ld s a r e m a n d a t o r y . In Norway the Halden r e a c t o r v e s s e l ha s been e s t i m a t e d to be s a f e to a to ta l f a s t neu-t ron exposure of 101 8 nvt . In the United S ta tes of A m e r i c a a su rvey has been m a d e of the f a s t neu t ron e x p o s u r e of s o m e p o w e r r e a c t o r v e s s e l s [12] . Of the 19 r e a c t o r s su rveyed , 15 may exper ience exposures of m o r e than 1018 nvt d u r i n g t h e i r l i f e t i m e , and 8 m a y r e c e i v e e x p o s u r e s of m o r e than 1019 nvt . The P M - 2 A r e a c t o r was the f i r s t to r e a c h 1019 nvt ; i t h a s now b e e n t a k e n out of o p e r a t i o n .

A n o t h e r a p p r o a c h would be t o d e s i g n the v e s s e l to the w o r s t p o s s i b l e c o n d i t i o n s . T h e f i r s t Swed i sh p o w e r r e a c t o r , a t  g e s t a , w a s d e s i g n e d a t an e a r l y p e r i o d , when it was fe l t tha t not enough was known about r ad i a t i on d a m a g e e f f e c t s on the m a t e r i a l u s e d and i t was t hus dec ided to a s s u m e the whole v e s s e l b r i t t l e , that i s , all ca lcula ted s t r e s s e s a re below yield [13,14].

In the Uni ted Kingdom it h a s b e e n the p r a c t i c e to r e d u c e the r i s k of b r i t t l e f a i l u re by mainta in ing the r e a c t o r p r e s s u r e v e s s e l s at a ce r t a in mini-m u m t e m p e r a t u r e , which i s a s s e s s e d f r o m c r a c k a r r e s t t e s t s , c h a n g e s in th i s t e m p e r a t u r e being e s t ima ted f r o m Charpy spec imen t r ans i t ion t e m p e r a -t u r e c h a n g e s [15] . O p e r a t i o n a l c r i t e r i a , b a s e d on a p e r m i s s i b l e a r e a in a p r e s s u r e - t e m p e r a t u r e d i a g r a m have a l so been u s e d in the United S ta t e s of A m e r i c a [12] and s i m i l a r c o n s i d e r a t i o n s have been r e p o r t e d f r o m G e r m a n y [16] and Sweden . It would s e e m d e s i r a b l e to i n v e s t i g a t e f u r t h e r the n e e d s f o r s u c h o p e r a t i n g c r i t e r i a and p r a c t i c e s which a r e in use at p r e s e n t .

19

It h a s a l so b e e n p r o p o s e d to include o t h e r new d e s t r u c t i v e t e s t s on the m a t e r i a l s to be used fo r the v e s s e l , such as de te rmina t ion of f r a c t u r e tough-n e s s p r o p e r t i e s as funct ion of neut ron exposure [6] .

An a l t e r n a t i v e to m e a s u r e m e n t s on t e s t s p e c i m e n s , i r r a d i a t e d i n s i d e the v e s s e l , could be to p e r f o r m m e a s u r e m e n t s on the v e s s e l i t se l f as i t i s p r e s s u r i z e d , a s i t s t e m p e r a t u r e i s i n c r e a s e d , e t c . At the K a h l BWR in G e r m a n y an e x p e r i m e n t a l p r o g r a m m e inc ludes elongation m e a s u r e m e n t s on the i n t e r n a l and e x t e r n a l s u r f a c e s of the p r e s s u r e v e s s e l dur ing ope ra t ion .

Requirements due to inaccessibility for periodic inspections

The d i f f i cu l ty o r i m p o s s i b i l i t y of p e r f o r m i n g r e g u l a r p e r i o d i c i n s p e c -t ions on r e a c t o r s y s t e m s a f t e r they have been t aken in to o p e r a t i o n has led to a g r e a t n u m b e r of addi t ional r e q u i r e m e n t s beyond those given in nat ional c o d e s . Whi l e r a d i a t i o n e m b r i t t l e m e n t , be ing a change in the p r o p e r t y of m a t e r i a l , wi l l m a i n l y have an e f f e c t on m a t e r i a l c o n s i d e r a t i o n s , t he i n -a c c e s s i b i l i t y f o r i n s p e c t i o n d e m a n d s add i t iona l r e q u i r e m e n t s f o r the whole f a b r i c a t i o n f r o m the des ign to the f inal a c c e p t a n c e t e s t s .

Many of the a n s w e r s to the IAEA inqui ry s ta ted that r e g u l a r inspec t ions should con t inue to be p e r f o r m e d a s f a r a s p o s s i b l e . The Uni ted Kingdom a n s w e r points out that i t i s not poss ib le to give any gene ra l r u l e s for r egu l a r i n s p e c t i o n s , but tha t r e g u l a t i o n s may be l i m i t e d to r e q u i r e the o b s e r v a n c e of any e x a m i n a t i o n cond i t ions la id down by the l i c e n s i n g a u t h o r i t y . T h i s , of c o u r s e , m e a n s a " c a s e - b y - c a s e a p p r o a c h " wh ich i s , h o w e v e r , t y p i c a l of m o s t n u c l e a r p lan t l i c e n s i n g p r o c e d u r e s and which r e f l e c t s the p r e s e n t s t a t e of d e v e l o p m e n t in the n u c l e a r t echno logy .

T y p i c a l of the i n spec t i on r u l e s thus e s t a b l i s h e d a r e the A u s t r a l i a n r e -q u i r e m e n t s on the HIFAR r e s e a r c h r e a c t o r system-, which include repet i t ion of the accep tance t e s t s fo r components when they a r e r emoved o r d ismant led f o r i n s p e c t i o n and m a i n t e n a n c e . Regu la r v i s u a l i n s p e c t i o n s of the r e a c t o r v e s s e l a r e p e r f o r m e d d u r i n g e a c h annua l m a j o r m a i n t e n a n c e s h u t - d o w n . S i m i l a r r e q u i r e m e n t s a r e in f o r c e in o t h e r c o u n t r i e s .

I t m a y s o m e t i m e s be p o s s i b l e to i s o l a t e n u c l e a r s y s t e m c o m p o n e n t s , such a s s t e a m g e n e r a t o r s , and to p e r f o r m a n o r m a l pe r iod i c in spec t ion on t h e m . In m o s t c a s e s , and e s p e c i a l l y as r e g a r d s the r e a c t o r v e s s e l i t s e l f , pe r iod ic inspec t ions would have to be v e r y l imi ted in scope . It i s often only poss ib le to p e r f o r m a supe r f i c i a l visual inspect ion during m a j o r annual main-t e n a n c e s h u t - d o w n s , us ing h o r o s c o p e s o r o the r op t ica l a ids ; t h i s i s m u c h l e s s than m o s t r u l e s f o r p e r i o d i c i n s p e c t i o n s s p e c i f y .

R e g u l a r i n s p e c t i o n s , a s n o r m a l l y c o n d u c t e d on c o n v e n t i o n a l b o i l e r s , ' be ing i m p o s s i b l e , m o s t c o u n t r i e s have na tu ra l l y r e q u i r e d h ighe r s t a n d a r d s of r e l i a b i l i t y f o r r e a c t o r v e s s e l s . T h e s e h ighe r s t a n d a r d s in t u r n ca l l f o r a m o r e e x t e n s i v e knowledge of the s t a t i c and o p e r a t i o n a l p r o p e r t i e s of the v e s s e l , i . e . a c a r e f u l s t r e s s a n a l y s i s and a t h o r o u g h eva lua t i on of a l l e f -f e c t s tha t m a y be d e l e t e r i o u s . Thus , c o r r o s i o n r e s i s t a n c e and ana lys i s of a l l phenomena that m a y endange r the s t r u c t u r e in the long t e r m have g e n e r -a l ly been r e q u i r e d .

M o s t c o u n t r i e s have r e q u i r e d a c a r e f u l a n a l y s i s of a l l s t r e s s e s in the v e s s e l beyond the s imple ca lcula t ion of wall th ickness specif ied in the codes .

2 0

The objec t ive of the s t r e s s ana lys i s ha s been d i f f e r en t in v a r i o u s coun t r i e s . Some t imes the purpose has been to p e r f o r m calculat ions in o rde r to d iscover and e n s u r e aga ins t i nadequac ie s in ex i s t ing codes fo r the m o r e complex nu-c l e a r r e a c t o r v e s s e l s (Italy), o r to de t e rmine the r e a l f ac to r of sa fe ty , a lso taking into account r ad ia t ion damage (Norway). The Norwegian answer a lso quoted tha t a s a r e s u l t of t h e s e inves t iga t ions i t was dec ided to u se a m a x i -m u m weld e f f i c i e n c y f a c t o r of 0 . 7 5 long i tud ina l w e l d s in the d e s i g n c a l c u l a t i o n s .

O t h e r a n s w e r s s t a t e tha t the u s u a l s c h e m a t i c code c a l c u l a t i o n s , taking a l i m i t e d v a l u e f o r m e m b r a n e s t r e s s e s wi th a s a f e t y f a c t o r , l e a v i n g a l l unca lcu la t ed s t r e s s i n c r e a s e s to be c a r r i e d by the m a r g i n s ava i l ab le , have been cons ide red u n s a t i s f a c t o r y for r e a c t o r v e s s e l s , which r equ i r e a detailed a n a l y s i s of a l l s t r e s s i n c r e a s e s due to open ings , c h a n g e s in t e m p e r a t u r e , e t c . ( G e r m a n y , N e t h e r l a n d s , Sweden [13] , UK). T h e r m a l s t r e s s e s have in s o m e c a s e s been given s p e c i a l a t tent ion ( e .g . G e r m a n y , USSR [9], USA). The J a p a n e s e a n s w e r s p e c i f i e s that t h e r m a l s t r e s s e s have to be cons ide red in the m a x i m u m al lowable working p r e s s u r e , and the G e r m a n answer points s p e c i f i c a l l y to the addi t ional t h e r m a l s t r e s s e s tha t m a y occu r in thick walls at s t e a d y - s t a t e opera t ion and espec ia l ly during power changes in the r e a c t o r , a s well a s to the o c c u r r e n c e of addi t ional t h e r m a l s t r e s s e s due to r ad ia t ion h e a t i n g of the m a t e r i a l s . T h i s h a s a l s o b e e n a m a i n c o n s i d e r a t i o n in the USSR [9] .

F o r the M a r v i k e n r e a c t o r v e s s e l in Sweden a comple t e s t r e s s ana lys i s had to be m a d e , t ak ing into account a l l n o r m a l r e a c t o r ope ra t i ng condi t ions ( inc luding f a s t s h u t - d o w n s ) and a l s o s o m e t y p e s of a c c i d e n t s . F o r t h e s e i t was r e q u i r e d t h a t p l a s t i c d e f o r m a t i o n of the componen t s would not be so g r e a t t ha t t h e i r func t ion would be i m p a i r e d . T h i s i s the only r e p o r t e d in -s t a n c e of s p e c i a l r e q u i r e m e n t s f o r r e a c t o r acc iden t cond i t i ons .

D i f f e r e n t t y p e s of r e a c t o r s g ive s o m e w h a t d i f f e r e n t r e q u i r e m e n t s a s conce rns the s t r e s s ca lcu la t ions . C r e e p i s not covered by the ASME Section III Code except in the way that the tabula ted allowable s t r e s s in tens i t i es have been l im i t ed to a t e m p e r a t u r e range below that a t which c r e e p behaviour be -c o m e s dominant . Th i s r a n g e i s s t i l l adequate f o r the wa t e r - coo l ed r e a c t o r s now f o r m i n g the m a i n p a r t of the Uni ted S t a t e s c o m m e r c i a l p o w e r r e a c t o r product ion . In the United Kingdom where gas -coo led r e a c t o r s cal l f o r higher coolant and v e s s e l t e m p e r a t u r e s , c r e e p is a m a j o r concern . S imi la r ly , some c o n c e r n about the adequacy of the e a r l i e r ASME code s e c t i o n s has been r e -por t ed f r o m the United S ta t e s of A m e r i c a f o r high t e m p e r a t u r e l i q u i d - m e t a l cooled s y s t e m s [17] .

I t h a s b e e n s t a t e d t h a t a c o m p l e t e s t r e s s a n a l y s i s of a v e s s e l d e s i g n m a y add up to 20% to the c o s t of t he v e s s e l [18] .

A n o t h e r s i g n i f i c a n t a c t i o n t a k e n to c o u n t e r a c t the i n a c c e s s i b i l i t y f o r r e g u l a r i n s p e c t i o n s i s the r e s e a r c h p r o g r a m m e tha t h a s b e e n e s t a b l i s h e d in the United Kingdom by the C e n t r a l E l e c t r i c i t y Genera t ing Board to pred ic t the p e r f o r m a n c e of s t e e l r e a c t o r p r e s s u r e s y s t e m c o m p o n e n t s [19] . The m a i n a r e a s of i n t e r e s t in th i s inves t iga t ion a r e c r e e p d i s to r t ion , c r e e p rup -t u r e , and h igh s t r a i n f a t i g u e . Some e x p e r i m e n t s have a l s o b e e n m a d e to inves t iga t e the m a r g i n s be tween ac tua l ope ra t i ng condi t ions and those which would c r e a t e d i s t o r t i o n of the componen t s by s h o r t - t e r m yielding.

2 1

Addit ional r e q u i r e m e n t s have also been placed on the whole manufac tu r -ing p r o c e d u r e , f r o m the se lec t ion of m a t e r i a l s to the s t r e s s re l ieving proce-d u r e , and on the i n s p e c t i o n . Of c o u r s e v a r i o u s i n s p e c t i o n p r o c e d u r e s a r e of ten e m p h a s i z e d , a s the ob jec t ive behind m o s t of t hese r e q u i r e m e n t s is the v e r i f i c a t i o n tha t the s t r i c t s p e c i f i c a t i o n s have been ma in ta ined in c o n s t r u c -t i on . T h i s ha s o f t en m e a n t the d e v e l o p m e n t of new o r m o r e advanced non-d e s t r u c t i v e i n s p e c t i o n t e c h n i q u e s , e . g . the u s e of a c c e l e r a t o r s f o r r a d i o -graphy , u l t r a son ic methods (which a re now speci f ied to a much g rea t e r extent than p rev ious ly ) , new l eak t e s t s , e tc . These new or m o r e re f ined techniques a r e now b e i n g f u r t h e r app l i ed to the f a b r i c a t i o n of m o r e c o n v e n t i o n a l p r e s s u r e v e s s e l s .

F o r a l l s t e p s in des ign , f a b r i c a t i o n and i n spec t i on t h e r e i s a l so a gen-e r a l ca l l f o r c a r e f u l and extens ive documentat ion of all act ions. The var ious r e q u i r e m e n t s a r e s o m e t i m e s typ ica l f o r s p e c i f i c r e a c t o r types and may not have g e n e r a l va l id i ty .

Among the r e q u i r e m e n t s quoted in m a n y a n s w e r s a r e :

(a) S p e c i a l c a r e m u s t be e x e r t e d in the s p e c i f i c a t i o n , s e l e c t i o n and inspec t ion of m a t e r i a l s to be u sed , to avoid l amina t ions , inc lus ions and o the r d e f e c t s . Inspec t ion , both as r e g a r d s c h e m i c a l ana ly s i s , des t ruc t ive and non-des t ruc t ive t es t ing (e .g . by u l t rasonic methods) i s of ten s t r i c t e r than u sua l and well specif ied (e .g . Germany , Japan, Sweden, UK, USSR [9] ).

(b) F o r we lded c o n s t r u c t i o n s , s p e c i a l r e q u i r e m e n t s have b e e n s e t up f o r we lde r qual i f ica t ion , p rehea t ing , and weld inspect ion (e .g . UK). F u l l p e n e t r a t i o n w e l d s a r e n o r m a l l y s p e c i f i e d . In C a n a d a i t h a s been s p e c i f i e d tha t the welds m u s t have a con f igu ra t ion such as to p e r m i t r ad iograph ic examinat ion. One hundred pe r cent radiography of al l welds i s n o r m a l l y spec i f ied ( e . g . Be lg ium, Ge rmany , Japan) .

(c) The s t r e s s r e l i e v i n g o p e r a t i o n i s to be checked , and s t r a i n , t e m p e r a t u r e and v e s s e l m o v e m e n t r e c o r d s a r e to be t a k e n (UK). Add i t i ona l s t r e s s r e l i e f r e q u i r e m e n t s a r e s o m e t i m e s l a i d down ( C a n a d a ) .

(d) T h e h y d r a u l i c t e s t s a r e in m a n y c a s e s p e r f o r m e d m o r e s t r i c t l y than n o r m a l l y and u n d e r s t r i c t s u p e r v i s i o n (Belg ium, UK). It has been pointed out tha t hydrau l i c t e s t i n g to e x c e s s i v e p r e s s u r e s may be u n d e s i r a b l e and r e s u l t in undue s t r a i n on the v e s s e l (Aus t ra l i a ) .

(e) E m e r g e n c y r e a c t o r c o n t a i n m e n t v e s s e l s a r e o f t e n s p e c i f i e d and bui l t as p r e s s u r e v e s s e l s . The p r e s s u r e t e s t s on t h e s e , however , a r e m o s t o f t en adapted to t h e i r s p e c i a l func t ion , which i s to s e r v e a s a b a r r i e r a g a i n s t l e a k a g e in a d v e r s e cond i t ions , r a t h e r than to s a f e ly wi ths tand a c e r t a i n p r e s s u r e . These v e s s e l s a r e thus usually p e r i o d i c a l l y l e a k - t e s t e d a t d e s i g n p r e s s u r e s , r a t h e r t h a n t e s t e d a t a c e r t a i n o v e r - p r e s s u r e .

(f) L e a k t i g h t n e s s has been given spec i a l a t tent ion in many c a s e s (Aus-t r a l i a , D e n m a r k , G e r m a n y , J a p a n , UK). The d e g r e e of l e a k -t i gh tnes s r e q u i r e d i s not always de t e rmined by safe ty in containment of r a d i o a c t i v e m a t e r i a l s , but a l s o by the p o s s i b i l i t y of l o s s of ex-pens ive coo lan t s , such a s heavy w a t e r and he l ium. Leak t e s t s thus v a r y v e r y much f r o m soap wa te r t e s t s through vacuum t e s t s t o f r e o n and h e l i u m - g a s l eak t e s t s .

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It i s i n t e r e s t i n g to no te tha t o r i g i n a l s t r i c t r e q u i r e m e n t s now in s o m e i n s t a n c e s a r e be ing r e l a x e d , as e x p e r i e n c e adds knowledge and shows such r e l a x a t i o n s to be p e r m i s s i b l e . One e x a m p l e of t h i s i s the e a r l y r e q u i r e -m e n t f o r c o r r o s i o n r e s i s t a n c e in the p r i m a r y s y s t e m s of r e a c t o r s . In some r e a c t o r s u n c l a d c a r b o n s t e e l s a r e now u s e d s i n c e e x t e n s i v e e x p e r i m e n t s show tha t c o r r o s i o n r a t e s c a n be c o n t r o l l e d and do not i n t r o d u c e unknown r i s k s d u r i n g the r e a c t o r l i f e t i m e s (USA and USSR). T h e b a c k g r o u n d f o r s u c h r e l a x a t i o n s i s , h o w e v e r , a l w a y s v e r y e x t e n s i v e k n o w l e d g e .

A ddi tional re quire m en ts

A n u m b e r of m o r e s p e c i a l i z e d r e q u i r e m e n t s have a l s o b e e n g iven by s o m e c o u n t r i e s :

Canada : Addi t iona l u l t r a s o n i c i n s p e c t i o n of welded jo in t s was r e q u i r e d . Cas t ings and r e p a i r s to cas t ings were subject to additional radio-g raph ic , u l t r a son ic and dye -pene t r an t inspect ion.

Germany : A welding f a c t o r of 1.0 was a imed at by adopting the code ' s s t r i c t -est welding and des ign r e q u i r e m e n t s . S p e c i a l s p e c i f i c a t i o n s w e r e i n m a n y c a s e s g iven f o r s u r f a c e f i n i s h e s .

J a p a n : Spec i a l a t t en t ion i s g iven to s a f e t y v a l v e s , and to the s a f e d i s -p o s a l of r a d i o a c t i v e w a s t e s f r o m t h e m .

UK: A t h o r o u g h v i s u a l e x a m i n a t i o n of the v e s s e l a f t e r s t r a i n r e l i e f i s r e q u i r e d , fo l lowed by m a g n e t i c c r a c k de t ec t ion of s u s p e c t e d a r e a s .

USSR: [9] R ing-shaped por t ions of the v e s s e l s a r e forged without any longi-tudinal jo in t s . All nozz les a r e double-welded to the v e s s e l .

Exceptions granted from existing codes

Although the na t iona l codes thus have been gene ra l ly appl ied , some not-able e x c e p t i o n s have b e e n m a d e . With the F r e n c h G - 2 and G - 3 r e a c t o r s i t was obvious ly n e c e s s a r y to al low a g r e a t l a t i tude in the code i n t e r p r e t a t i o n a s t hey have p r e s t r e s s e d c o n c r e t e r e a c t o r p r e s s u r e v e s s e l s of an e n t i r e l y new d e s i g n c o n c e p t .

The F r e n c h a n s w e r a l s o s t a t e d t ha t , a l though the " S e r v i c e d e s M i n e s " n o r m a l l y i s the cont ro l body fo r p r e s s u r e v e s s e l s , including nuc lea r sys tems, l i q u i d - m e t a l cooled f a s t r e a c t o r s y s t e m s have been exempted f r o m that con-t r o l in view of the v e r y s p e c i a l n a t u r e of t h e s e v e s s e l s .

Many s m a l l e r excep t ions w e r e r e p o r t e d , p e r t a i n i n g to only c e r t a i n a s -pec t s of the des ign o r cons t ruc t i on a s , e . g . , f o r the F r e n c h EDF-1 andEDF-2

23

r e a c t o r s , f o r the Ind ian T a r a p u r s t a t i o n , and f o r the N o r w e g i a n Ha lden r e a c t o r p r i m a r y s y s t e m .

VII . CONCLUSION

It has been poss ib l e to apply the n o r m a l na t iona l p r e s s u r e v e s s e l codes to m o s t of the p r e s s u r i z e d n u c l e a r r e a c t o r s built so f a r , and the bodies n o r -m a l l y r e s p o n s i b l e f o r the a d m i n i s t r a t i o n of codes and r egu la t i ons have s t i l l had t h i s f u n c t i o n to f u l f i l , e v e n if s o m e t i m e s the p r o c e d u r e s d i f f e r f r o m t h e r o u t i n e f o r b o i l e r s and c o n v e n t i o n a l v e s s e l s .

Code a p p l i c a t i o n s to n u c l e a r s y s t e m s have c a u s e d s e v e r e p r o b l e m s . G e n e r a l l y many addi t ional o r s e p a r a t e r e q u i r e m e n t s have been made beyond t h o s e of the c o d e s . E v e n t h e s e c o u n t r i e s that have m o d e r n and t echn ica l l y w e l l - a d v a n c e d c o d e s have had to s t r e t c h the r e q u i r e m e n t s and ex t end the s c o p e of t h e s e c o d e s .

It i s , of c o u r s e , only n a t u r a l that m a n y of the ex i s t ing codes s e e m old-f a s h i o n e d when t h e y a r e app l i ed to a f i e ld i n wh ich s u c h r a p i d t e c h n o l o g i c a l d e v e l o p m e n t i s t a k i n g p l a c e a s in n u c l e a r p o w e r e n g i n e e r i n g and in wh ich new p r o b l e m s a r e r a i s e d by the specia l opera t ing condit ions. Nuclear v e s s e l app l i ca t ions have a l so highl ighted s h o r t c o m i n g s of the p r e s e n t codes , above a l l the i n a d e q u a c y f o r big and c o m p l e x v e s s e l s of the s c h e m a t i c d e s i g n ap-p r o a c h t y p i c a l f o r a l m o s t a l l c o d e s .

T h e c r i t i c i s m of t h i s s i m p l e a p p r o a c h , wh ich p r e s c r i b e s c a l c u l a t i o n of wa l l t h i c k n e s s e s of c e r t a i n g iven v e s s e l s h a p e s by a s i m p l e f o r m u l a , i s b a s e d on i t s o v e r - s i m p l i f i c a t i o n of ac tua l cond i t ions . It t akes in to account a t oo l i m i t e d n u m b e r of p h y s i c a l m a t e r i a l p r o p e r t i e s . The s a f e t y f a c t o r i s l a r g e , o f t e n r e s u l t i n g in u n n e c e s s a r i l y t h i ck w a l l s wi th a c c o m p a n y i n g f a b r i c a t i o n d i f f i c u l t i e s and c o s t s , b e c a u s e i t m u s t c o v e r a wide v a r i e t y of c o n t i n g e n c i e s s u c h a s d e s i g n a s p e c t s , l a c k of fu l l i n s p e c t i o n of the v e s s e l and knowledge of the des ign and, f ina l ly , quite of ten s imply bad des ign. The complex c a s e s of n u c l e a r v e s s e l s have brought out the in su f f i c i enc ie s of th i s app roach and have r e q u i r e d a comple te s t r e s s ana lys i s of the v e s s e l s . Only in a few c a s e s , h o w e v e r , has the consequence been d r a w n that the comple t e s t r e s s a n a l y s i s , r e p r e s e n t i n g good des ign eng inee r ing aga ins t s p e c i f i c pos -s i b l e c a u s e s of f a i l u r e , shou ld p e r m i t m o r e r e a l i s t i c s a f e t y f a c t o r s t o be u s e d . As a g e n e r a l r u l e , the r e q u i r e m e n t s of the old codes have s t i l l been the m i n i m u m o n e s .

T h e r e l u c t a n c e to d e v i a t e f r o m old c o d e s c a n e a s i l y be e x p l a i n e d by the good e x p e r i e n c e of acc ident p revent ion that they have given. It has a lso r e c e n t l y b e e n po in ted out tha t we a r e not y e t r e a d y wi th o u r p r e s e n t t e c h -niques to d i s c a r d comple te ly the old "des ign s t r e s s " concept to design against f a i l u r e of any kind s t a r t i n g f r o m bas i c m a t e r i a l p r o p e r t i e s [20]. St i l l , the i n su f f i c i ency of the old a p p r o a c h has been c l e a r l y r e a l i z e d in n u c l e a r c a s e s a s well as fo r m o r e convent ional v e s s e l s [21] and impor t an t s t eps have been t a k e n t o w a r d s m o r e qual i f ied des ign r u l e s in the ASME Sect ion III Code, in the w o r k by the ISO working g roup now occupied with fo rmu la t i ng a new code f o r n u c l e a r v e s s e l s , and in s e v e r a l new n a t i o n a l n u c l e a r c o d e s and c o d e s u p p l e m e n t s .

24

The addi t iona l r e q u i r e m e n t s beyond those of the ex i s t i ng codes , which have b e e n m a d e f o r n u c l e a r v e s s e l s , have , to a g r e a t ex t en t , involved de -ve lopmen t of m o r e c a r e f u l des ign t echn iques , new and improved fab r i ca t ion m e t h o d s and new inspec t ion p r o c e d u r e s . Good eng inee r ing and qual i ty con-t r o l have been v e r y much e m p h a s i z e d in the cons t ruc t ion of nuc l ea r v e s s e l s . T h i s h a s , beyond any doubt , b e n e f i t e d the whole f i e l d of p r e s s u r e v e s s e l c o n s t r u c t i o n and m a y we l l be r e f l e c t e d in a m e n d e d o r new c o d e s f o r non-n u c l e a r v e s s e l s .

I m p o r t a n t a s p e c t s of r e a c t o r v e s s e l o p e r a t i o n , such as l i f e t i m e and l i -m i t a t i o n s in o p e r a t i n g condi t ions , al though they a r e c lose ly r e l a t e d to code p r o b l e m s , cannot be c o v e r e d in codes as they a r e dependent on the v a r y i n g o p e r a t i n g c o n d i t i o n s in e a c h r e a c t o r . T h e s e a s p e c t s m u s t , h o w e v e r , be given s e r i o u s cons ide ra t ion and a m o r e unif ied approach to them would seem v e r y d e s i r a b l e .

Many c o u n t r i e s a r e now devo t ing e f f o r t s to f o r m u l a t i n g new c o d e s o r code supp l emen t s to cove r nuc lea r v e s s e l c a s e s . These may show a na tu ra l t e n d e n c y to r e f l e c t the l o c a l l y c h o s e n l ine of d e v e l o p m e n t f o r r e a c t o r s y s t e m s . With the v a r i e t y of v e r y d i f f e r e n t s y s t e m s that a l r e a d y ex i s t and which wi l l b e c o m e g r e a t e r a s w o r k con t inues on advanced c o n v e r t e r s and b r e e d e r s i t m u s t be hoped that enough f lex ib i l i ty in code f o r m u l a t i o n i s r e -ta ined to p e r m i t u p - d a t i n g and appl ica t ion to t h e s e s y s t e m s .

R E F E R E N C E S

[ 1 ] d e J O N G , K .J . , d e P A T E R , C . , van VEEN, M . C . , Experience of the design, ca lcu la t ion and manu-

facture for power reactor components, 3rd U N Int . Conf . PUAE, 1 9 6 4 , Paper 728.

[ 2 ] L A N C A S T E R , J . F . , A Comparison of U n i t e d States, European and British C o m m o n w e a l t h Codes for

the Construction of Welded Boilers and Pressure Vessels, A S M E preprint 6 1 - S A - 4 0 ( 1 9 6 1 ) .

[ 3 ] AMERICAN SOCIETY OF M E C H A N I C A L ENGINEERS, Cases 1270N-5 , 1271N, 1272N-5 , 1273N-7.1274N-6,

1275N and 1 2 7 6 N - 1 , ASME Case Interpretations, New York (1962).

[ 4 ] LLOYD'S REGISTER OF SHIPPING, Provisional Requirements for the Design, Manufacture and Test ing

of Pressure Components of Land-based Nuclear Instal lat ions, Norfolk House, Croydon, Surrey (1960 ) .

[ 6 ] A M E R I C A N SOCIETY OF M E C H A N I C A L ENGINEERS, ASME Boiler and Pressure Vessel Code, Section I I I ,

Rules for Construction of Nuclear Vessels, New York (1963).

[ 6 ] G A I N E S , A . L. , PORSE, L . , Problems in the design and construction of large reactor vessels, 3rd U N

In t . Conf . PUAE, 1 9 6 4 , Paper 2 2 7 .

[ 7 ] A M E R I C A N S O C I E T Y OF M E C H A N I C A L ENGINEERS, C r i t e r i a of Sect ion I I I o f the A S M E Boiler and

Pressure Vessel C o d e for N u c l e a r Vessels, N e w York ( 1 9 6 4 ) .

[ 8 ] PEMBERTON, H . N . , CROSSLEY, E. , Inspection of pr imary circuits and reactor pressure vessels of nu-

clear power p l a n t , J. Br. nucl . Energy Conf . 6. 2 (1961) 7 9 - 9 5 .

[ 9 ] S T E K O L N I K O V , V . V . et a l . , High pressure vessels of l ight -water cooled and moderated power reactors,

3rd U N Int . Conf. PUAE , 1964, Paper 331.

[ 10] T O B I N , J. С . , WECHSLER, M . S . , ROSSIN, A . D . , Radiat ion- induced changes in the properties of non-

fuel reactor mater ia ls , 3rd UN Int . Conf. PUAE, 1964, Paper 242.

[ 1 1 ] M Y E R S , H . P. , GROUNES, M . , H A N N ERZ, N . E. , I r radiat ion behaviour of Swedish steels for reactor

pressure vessels, 3rd U N Int . Conf . PUAE, 1 9 6 4 , Paper 420 .

[ 1 2 ] D i N U N N O , J.J. , H O L T , A . B. , Radiation embr i t t lement of reactor vessels, Nucl . Saf. 4 2 (1962) 34.

[ 1 3 ] HELLSTRÖM, О . , Design and manufacture of the reactor pressure vessels for the Ägesta and Morv iken

power stations and some future developments, 3rd U N In t . Conf. PUAE, 1964 , Paper 810.

[ 1 4 ] HELLSTROM, O. , NILSSON, R. , Problems in Pressure Vessel Design and Manufacture, AE-104 Stockholm (1963).

25

[ 1 5 ] HARRIES, D . R. et a l . , I r radiat ion behaviour of steel as a structural and cladding m a t e r i a l , 3rd U N

Int . Conf. PUAE, 1964 , Paper 162.

[ 1 6 ] KNÖDLER, D. , SCHALLER, К . , Der Einfluss der Bestrahlung auf Auslegung und Betrieb von Reaktor-

druckbehältern, Kerntechnik 6 ( 7 / 8 ) (1964) 339.

[ 1 7 ] HAYES, W . C . , Comments on the Appl icat ion of A S M E and ASA Boiler and Piping Codes to Sodium

Systems N A A - S R - 4 1 0 2 .

[ 1 8 ] Guide to Nuclear Power Cost Evaluat ion, USAEC rep. T I D - 7 0 2 5 ( V o l . 3 ) (1962) .

[ 1 9 ] TOWNLEY, C . H . A . , PROCTER, E . , Investigations to predict the performance of steel reactor pressure

circuit components in service, 3rd UN Int. Conf. PUAE, 1964, Paper 144.

[ 2 0 ] BUSH, S. H . , Special materials for reactor construction and their methods of fabrication, Atomic Energy

Review 1 IAEA, Vienna (1963) 43 -92 .

[ 2 1 ] CARLSON, W . B . , Pressure Vessel Design Requirements in the Future, Weld. J. 40 6 (June 1961)265s-71s.

26

ANNEX

NATIONAL REGULATIONS AND CODES AND THEIR ADMINISTRATION

AUSTRALIA

The p r inc ipa l code i s the Aus t r a l i an Standard Rules fo r the Design, Con-s t r u c t i o n , Inspec t ion and Opera t ion of B o i l e r s and Unf i red P r e s s u r e V e s s e l s and t h e i r A p p u r t e n a n c e s , A u s t r a l i a n S t a n d a r d No. CB. 1, pub l i shed by the S tanda rds Assoc ia t ion of A u s t r a l i a . It i s commonly known as the SAA Boi l e r Code.

T h i s code h a s no l e g a l o r r e g u l a t o r y s t a t u s by i t s e l f , but i t h a s b e e n w r i t t e n in to the s t a t u t o r y r e q u i r e m e n t s of s o m e of the A u s t r a l i a n S t a t e s . In a l l c a s e s b o i l e r s m u s t be r e g i s t e r e d and have a c e r t i f i c a t e of w o r t h i n e s s , which i s to be r enewed at pe r iod ic i n s p e c t i o n s .

New South W a l e s , Queens land , V i c t o r i a , South A u s t r a l i a and T a s m a n i a thus have a c t s which give the SAA B o i l e r Code l e g a l s t a t u s , in s o m e c a s e s g iving o t h e r s , s u c h a s r e l e v a n t B r i t i s h S t a n d a r d s , L l o y d ' s r u l e s o r ASME code a s a l t e r n a t i v e s . W h e r e the code a s ye t h a s not b e e n g iven th i s l e g a l s tanding the inspec t ion a u t h o r i t i e s have developed a pol icy which in p r ac t i ce m e a n s that the SAA B o i l e r Code i s u s e d . The a c t s a r e g e n e r a l l y a d m i n -i s t e r e d by the Sta te D e p a r t m e n t s of L a b o u r and I n d u s t r y , D e p a r t m e n t s of Mines , o r D e p a r t m e n t s of the I n t e r i o r , in which an inspect ion body is f o r m e d , in one c a s e a s s i s t e d by outs ide l i censed bo i le r i n s p e c t o r s .

The new v e r s i o n of the SAA B o i l e r Code P a r t 1 of 1962 r ecogn izes some f o r e i g n codes ( B r i t i s h S t a n d a r d s , L l o y d ' s r u l e s and the ASME B o i l e r Code) a s a c c e p t a b l e .

BELGIUM

T h e " R è g l e m e n t g é n é r a l p o u r l a p r o t e c t i o n du t r a v a i l " i s i s s u e d a s a r o y a l d e c r e e , the def in i t e c o n t e n t s , appl ica t ion and execut ion of which i s to be dec ided by the a d m i n i s t r a t i o n . The " R è g l e m e n t " c o n t a i n s a n u m b e r of t e c h n i c a l n o r m s , e s p e c i a l l y r e g a r d i n g b o i l e r s and s t e a m v e s s e l s , and a l s o s o m e n o r m s f o r p r e s s u r i z e d gas c o n t a i n e r s . T h e r e a lso exis t , bes ides th is d e c r e e , a n u m b e r of t echn ica l codes publ ished by the " Ins t i tu t belge de n o r -m a l i s a t i o n " and by the " A s s o c i a t i o n des i n d u s t r i e l s de Be lg ique" .

C o n t r o l of p r e s s u r e v e s s e l s i s e x e r c i s e d by the Inspec t ion Div i s ion of the " A d m i n i s t r a t i o n de la s é c u r i t é du t r a v a i l et l ' a d m i n i s t r a t i o n des m i n e s " . P e r i o d i c in spec t ions a r e p e r f o r m e d by p r iva te f i r m s that have been l i censed by the Gove rnmen t .

CANADA

In the P r o v i n c e of O n t a r i o , w h e r e al l Canad ian n u c l e a r r e a c t o r s so f a r have b e e n l o c a t e d , t he " B o i l e r s and P r e s s u r e V e s s e l A c t " i s t h e s t a t u t e app ly ing to b o i l e r s and p r e s s u r e v e s s e l s . The B o i l e r I n s p e c t i o n B r a n c h

27

of the O n t a r i o D e p a r t m e n t of L a b o u r i s n o r m a l l y r e s p o n s i b l e f o r the sa fe ty of b o i l e r s and p r e s s u r e v e s s e l s . The Act r e q u i r e s that the Chief I n s p e c t o r r e f e r to publ icat ions of the Canadian Standards Associa t ion and of the A m e r i -c a n Soc i e ty of M e c h a n i c a l E n g i n e e r s f o r r u l e s a s to a p p r o v a l of d e s i g n s , m a n u f a c t u r e , ins ta l la t ion , inspect ion, tes t ing and operat ion of bo i le r s , p r e s -s u r e v e s s e l s and p l a n t s . The Canad i an S t a n d a r d s A s s o c i a t i o n ' s s t a n d a r d CSA B51-1960 i s a "Code f o r the Cons t ruc t ion and Inspect ion of B o i l e r s and P r e s s u r e V e s s e l s " which in i t s t u r n r e f e r s to the ASME and ASA S tanda rd B31.1 codes a s the s t a n d a r d s governing the des ign , e tc . of p r e s s u r e v e s s e l s .

All p r o v i n c e s of Canada have m a d e s i m i l a r l e g i s l a t i v e p r o v i s i o n s , a l -though the d e g r e e to which the e n f o r c e m e n t agenc i e s a r e r e q u i r e d to follow the CSA and o the r codes m a y v a r y f r o m c a s e to c a s e .

DENMARK

The D a n i s h S t a n d a r d s DS316, 317, 318, 320 .1 and 320.2 pub l i shed by " D a n s k S t a n d a r d i s e r i n g s r ä d " cons t i tu t e the code f o r de s ign , m a n u f a c t u r e (welding) and inspec t ion of b o i l e r s and p r e s s u r e v e s s e l s . These codes wil l be r e v i s e d in a c c o r d a n c e with the I n t e r - N o r d i c INSTA recommenda t ion con-c e r n i n g weld ing p r e s s u r e v e s s e l s . The codes have an o f f i c i a l s t a t u s , and a r e u n d e r the c o n t r o l of the D a n i s h D i r e c t o r a t e of L a b o u r In spec t i on .

FRANCE

The F r e n c h n o r m s fo r the des ign , manufac tu re and inspect ion of bo i le r s and p r e s s u r e v e s s e l s a r e l a w s and d e c r e e s c o l l e c t e d in " R é g l e m e n t a t i o n d e s a p p a r e i l s à v a p e u r " and " R é g l e m e n t a t i o n d e s a p p a r e i l s à p r e s s i o n de g a z " , pub l i shed by the " A s s o c i a t i o n des p r o p r i é t a i r e s d ' a p p a r e i l s à v a p e u r e t é l e c t r i q u e s " (GAPAVE) . T h e s e l a w s and d e c r e e s c o n s t i t u t e r u l e s f o r s a f e t y and f o r o f f i c i a l c o n t r o l of v e s s e l s , but they do not contain a code f o r ca l cu la t ion of v e s s e l d e s i g n . Such a code e x i s t s f o r u n f i r e d p r e s s u r e v e s -s e l s only , SNCT No. 1, i s s u e d by "Synd ica t n a t i o n a l de c h a u d r o n n e r i e et t ô l e r i e " . T h i s code h a s no d i r e c t l e g a l r e c o g n i t i o n .

The l aws and d e c r e e s a r e admin i s t e r ed by the "Min i s t è r e de l ' i ndus t r i e , D i rec t ion des m i n e s " .

GERMANY

F o r b o i l e r s a n u m b e r of o lde r codes will in the n e a r fu tu re be r ep l aced by codes and c r i t e r i a d ra f t ed by the G e r m a n "Dampfkes se l - a n d D r u c k g e f ä s s -A u s s c h u s s " (DDA). T h e s e wi l l be e n a c t e d by the F e d e r a l G o v e r n m e n t by way of s t a t u t o r y - o r d i n a n c e s . The " A l l g e m e i n e po l ize i l i che B e s t i m m u n g e n f ü r D a m p f k e s s e l " s p e c i f y t e s t s and i n s p e c t i o n s f o r b o i l e r s .

The l e g a l b a s i s of t he b o i l e r codes i s the T r a d i n g and I n d u s t r i a l Code . The c o d e s t h e m s e l v e s a r e c o n s i d e r e d a s " R e g e l n d e r T e c h n i k " i s s u e d by v i r tue of the gene ra l admin i s t r a t i ve regula t ions fo r l and-based s t eam bo i l e r s .

2 8

" U n f a l l v e r h ü t u n g s v o r s c h r i f t D r u c k b e h ä l t e r " con ta ins s a f e t y r u l e s f o r unf i red p r e s s u r e v e s s e l s and p r e s c r i b e s the t e s t s and inspect ions to be pe r -f o r m e d . F o r des ign , m a n u f a c t u r i n g and i n s t a l l a t i on it r e f e r s to accep ted r u l e s of eng inee r ing , in p a r t i c u l a r to the " A D - M e r k b l ä t t e r " e s t ab l i shed by the " A r b e i t s g e m e i n s c h a f t D r u c k b e h ä l t e r " .

The "Unfa l lve rhü tungsvorschr i f tDruckbehä l te r " i s issued under a section of the "Re ich Insurance Code", and also by prac t ica l ly all the t rade a s soc ia -t ions conce rned . The t r ade as soc ia t ions a r e obliged to make su re that the e n f o r c e m e n t of i t is supe rv i sed by technica l i n s p e c t o r s .

E a c h p rov ince within the F e d e r a l Republ ic of G e r m a n y i s r e s p o n s i b l e f o r the o r g a n i z a t i o n of the t e c h n i c a l c o n t r o l . The c o m p e t e n t a u t h o r i t y in each "Land" i s i t s T rade Superv i so ry Off ice , which normal ly works through o r r e c o g n i z e s the " T e c h n i s c h e U b e r w a c h u n g s - V e r e i n e " ( t echn ica l s a f e t y c o n t r o l s e r v i c e s ) .

INDIA

The bo i l e r code i s the Indian Boi le r Regula t ions , which a r e binding on a l l b o i l e r o w n e r s and o p e r a t o r s by v i r t u e of the Ind ian B o i l e r s A c t . The Indian B o i l e r Regu la t i ons l ay down the c r i t e r i a f o r d e s i g n , c o n s t r u c t i o n , c o m m i s s i o n i n g , t e s t ing and inspec t ion fo r b o i l e r s . Unf i red p r e s s u r e v e s -s e l s come unde r the purview of the Indian F a c t o r i e s Act . T h e r e i s at p r e -sen t no code f o r unf i red p r e s s u r e v e s s e l s , but t h e , F a c t o r i e s Act s t ipu la tes i n s p e c t i o n by the I n s p e c t o r of F a c t o r i e s , who i s e m p o w e r e d to t ake s u c h ac t ion as i s n e c e s s a r y to e n s u r e s a f e t y . The Indian S t a n d a r d s Ins t i tu t ion intends to es tab l i sh an unf i red p r e s s u r e v e s s e l code, but this would not have a manda to ry s ta tus under the law.

T h e r e a r e Bo i l e r I n s p e c t o r a t e s and F a c t o r y I n s p e c t o r a t e s in each s ta te to en fo rce the Ac t s . These Inspec to ra t e s a r e guided by the Cen t r a l Bo i l e r s B o a r d and the Chief A d v i s o r of F a c t o r i e s in the M i n i s t r y of L a b o u r r e s p e c t i v e l y .

ITALY

The N a t i o n a l A s s o c i a t i o n f o r the C o n t r o l of C o m b u s t i o n (ANCC) h a s publ ished c i r c u l a r s which cons t i tu te the code. Both the code and i t s l ega l s t and ing a r e be ing r e v i s e d . The ANCC h a s a c e n t r a l pos i t ion c o n c e r n i n g both w r i t i n g and i n spec t i on .

J A P A N

The Regulation for Safety of Bo i le r s and P r e s s u r e Vesse l s is a Ministry of L a b o u r Ord inance which, t o g e t h e r with the M i n i s t r y of Labou r No t i ces , " B o i l e r Cons t ruc t ion Code" and " P r e s s u r e Ves se l Const ruct ion Code", ap-p l i e s t o b o i l e r s and p r e s s u r e v e s s e l s . E x e c u t i v e bod ie s a r e the L a b o u r S t a n d a r d s B u r e a u of the M i n i s t r y of L a b o u r and L a b o u r S tanda rds Of f i ces

29

and Labour S tandards Inspect ion Off ices in each p r e f e c t u r e . The inspections a r e p e r f o r m e d by a g e n t s , the B o i l e r A s s o c i a t i o n , the S a f e t y A s s o c i a t i o n o r the Y a s u d a F i r e and M a r i n e I n s u r a n c e Co . L t d .

N E T H E R L A N D S

" G r o n d s l a g e n w a a r o p de beeorde l ing van de cons t ruc t i e en het m a t e r i a l v a n s t o o m t o e s t e l l e n , d a m p t o e s t e l l e n en d r u k h o u d e r s b e r u s t " ( P r i n c i p l e s f o r the a s s e s s m e n t of the c o n s t r u c t i o n and of the m a t e r i a l s u s e d in the con-s t r u c t i o n of bo i l e r s and p r e s s u r e v e s s e l s ) t oge the r with a n u m b e r of supple-m e n t a r y and e x p l a n a t o r y p u b l i c a t i o n s h e e t s c o n s t i t u t e the c o d e , which i s manda to ry and has the s tanding of a regula t ion by v i r tue of the Steam Vesse l s Act and i t s d e c r e e s .

The i n s p e c t o r a t e which e n f o r c e s t h e s e l a w s i s the " D i e n s t voor het S toomwezen" (Boi le r In spec t ion D e p a r t m e n t ) .

A d e c r e e i s in p r e p a r a t i o n f o r u n f i r e d p r e s s u r e v e s s e l s which, as r e -g a r d s d e s i g n and c o n s t r u c t i o n , w i l l c o n f o r m c l o s e l y wi th the r e g u l a t i o n s m e n t i o n e d a b o v e .

NORWAY

The " W o r k e r s P r o t e c t i o n Act" of 1956 e s t a b l i s h e s th ree codes as having s t a t u s of law; " S t a n d a r d s and Rules f o r P o w e r B o i l e r s and S team P r e s s u r e P i p e - L i n e s " , " M a t e r i a l Speci f ica t ions and Rules f o r Calculat ion of Strength", and " S t a n d a r d s f o r Welding of B o i l e r s , P r e s s u r e V e s s e l s and S team P r e s -s u r e P i p e - L i n e s " .

The c o d e s a r e e n f o r c e d by the B o i l e r I n s p e c t i o n D e p a r t m e n t .

SWEDEN

A n u m b e r of c o d e s have b e e n compi l ed and pub l i shed by the P r e s s u r e V e s s e l C o m m i s s i o n and the Welding C o m m i s s i o n of the Roya l Swed i sh A c a d e m y of E n g i n e e r i n g S c i e n c e s , inc lud ing a " P r e s s u r e V e s s e l C o d e " , a " B o i l e r Weld ing Code" and a " S t e a m B o i l e r C o d e " . T h e r e i s a cont inuous e f f o r t to p u b l i s h new c o d e s f o r v a r i o u s s p e c i a l c a s e s . T h e s e c o d e s have no l ega l s tanding in t h e m s e l v e s but the Nat ional W o r k e r ' s P r o t e c t i o n B o a r d , which i s the compe ten t r e g u l a t o r y au thor i ty and which i s r e p r e s e n t e d on the a b o v e - m e n t i o n e d c o m m i s s i o n s , h a s a c c e p t e d and e n f o r c e s t h e m and t h e y a r e i n p r a c t i c e m a n d a t o r y .

Inspec t ions a r e c a r r i e d out by competent , l i censed pr iva te f i r m s . The re a r e no o f f i c i a l r u l e s r e g a r d i n g the n e u t r a l i n s p e c t i o n of convent ional p r e s -s u r e v e s s e l s du r ing m a n u f a c t u r e .

UNITED KINGDOM

The l aw (The F a c t o r i e s Ac t of 1961, s e c t i o n 32-39) g i v e s a m i n i m u m of gu idance on t e c h n i c a l q u e s t i o n s . Cond i t i ons of e x a m i n a t i o n s a r e to be

30

p r e s c r i b e d in r e g u l a t i o n s , wh ich have no t ye t b e e n w r i t t e n . E n g i n e e r i n g c o d e s e x i s t , e . g . L l o y d ' s r u l e s f o r b o i l e r s and u n f i r e d p r e s s u r e v e s s e l s , r u l e s of A s s o c i a t e d Of f i ce s T e c h n i c a l C o m m i t t e e (AOTC) and B r i t i s h Stan-d a r d s fo r b o i l e r s and welded p r e s s u r e v e s s e l s . F o r p r e s s u r e - b e a r i n g com-ponents of r e a c t o r uni t s g e n e r a l s chedu l e s of p r e - c o m m i s s i o n i n g inspec t ion s e r v i c e s and s u p p l e m e n t a r y i n s p e c t i o n and t e s t r e q u i r e m e n t s a r e conta ined in the Code of Assoc i a t ed Eng inee r ing I n s u r e r s . Des ign of r e a c t o r s y s t e m s genera l ly i s based upon the r e q u i r e m e n t s of B r i t i sh Standard 1500 for Fusion-Welded P r e s s u r e V e s s e l s f o r u s e in the c h e m i c a l o r a l l ied i n d u s t r i e s . Mi-n i m u m s u p e r v i s o r y p r o c e d u r e , deta i led inspect ion p rocedu re s for m a t e r i a l s , and m e t h o d s of c o n s t r u c t i o n a r e s p e c i f i e d f o r r e a c t o r s y s t e m s in L l o y d ' s "Survey of p r e s s u r e components f o r l and-based nuc lea r ins ta l la t ions — pro-v i s iona l r e q u i r e m e n t s 1960".

The F a c t o r i e s Act i m p o s e s a s t a tu to ry duty on the u s e r s of s t e a m bo i l e r s and p r e s s u r e v e s s e l s f o r the s a f e t y of t h e i r ope ra t ion . H e r M a j e s t y ' s F a c -t o r y I n s p e c t o r s of the M i n i s t r y of L a b o u r a r e r e s p o n s i b l e f o r the e n f o r c e -m e n t of the A c t .

The codes have no lega l s tanding in t h e m s e l v e s but in r e a c t o r c a s e s the A s s o c i a t e d E n g i n e e r i n g I n s u r e r s ' Code and the AOTC Code have had r egu la -to ry s t a tus by v i r tue of a condition of Nuc lea r Site L icences . They have been e n f o r c e d t h r o u g h the de ta i l ed d e s i g n s a f e t y s t u d i e s , s u p p l e m e n t e d by c o m -prehens ive and independent checks on the cons t ruc t ion , inspection and tes t ing of p r e s s u r e v e s s e l s by L l o y d ' s o r by A s s o c i a t e d Eng inee r ing I n s u r e r s . The s t a n d a r d s w r i t t e n by the B r i t i s h S t a n d a r d s Ins t i tu t ion and the Royal Society f o r P r e v e n t i o n of A c c i d e n t s a l s o have no s t a t u t o r y f o r c e but they a r e p r e -p a r e d , to a l a r g e e x t e n t , in c o n s u l t a t i o n wi th a u t h o r i t a t i v e bod ie s and a r e g e n e r a l l y a c c e p t e d by i n d u s t r y .

The s i t ua t i on wi l l p r o b a b l y change in the f u t u r e a s a r e s u l t of the new N u c l e a r I n s t a l l a t i o n s Ac t of 1965 and the new B . S . 3 9 1 5 s t a n d a r d of 1965.

USA

The code widely u s e d f o r de s ign , c o n s t r u c t i o n and in i t i a l i n spec t ion of b o i l e r s and p r e s s u r e v e s s e l s i s the A m e r i c a n Soc ie ty of M e c h a n i c a l E n g i n e e r s (ASME) B o i l e r and P r e s s u r e V e s s e l Code which s ince 1964 a l so i n c l u d e s a c o m p l e t e code s e c t i o n on n u c l e a r v e s s e l s .

This code cons t i tu tes a l ega l document in those s t a tes and munic ipal i t ies which chose to adopt i t . Some au thor i t i e s main ta in the i r own s e p a r a t e codes which, however , gene ra l l y a r e pa t t e rned a f t e r the ASME code.

In i t i a l i n s p e c t i o n i s a c c o m p l i s h e d by s t a t e s o r i n s u r a n c e c o m p a n y i n -s p e c t o r s who a r e c e r t i f i e d by the N a t i o n a l B o a r d of B o i l e r and P r e s s u r e V e s s e l I n s p e c t o r s , t he reby providing acceptance by all s t a t e s and au thor i t ies which have adopted the ASME code.

R e q u i r e m e n t s f o r r e c u r r i n g s e r v i c e i n s p e c t i o n s a r e i n the h a n d s of l oca l and o t h e r en fo rc ing agen t s , and admin i s t r a t i on o r e n f o r c e m e n t of such r e q u i r e m e n t s v a r y f r o m one s t a t e to ano the r .

31

USSR

T h e f o l l o w i n g r u l e s h a v e b e e n i s s u e d by t h e " S t a t e C o m m i t t e e of t h e Counci l of M i n i s t e r s of the USSR on Safety Inspec t ion in Indus t ry and Mining":

(a) " R u l e s f o r C a l c u l a t i n g t h e S t r e n g t h of S t e a m B o i l e r C o m p o n e n t s 1956" ;

(b) " R u l e s f o r t he C o n s t r u c t i o n and Safe U t i l i z a t i o n of S t e a m P i p e s and Hot W a t e r P i p e s 1957";

(c) " R u l e s f o r t h e C o n s t r u c t i o n and S a f e O p e r a t i o n of S t e a m B o i l e r s 1 9 5 7 " .

T h e s e r u l e s a r e b i n d i n g on a l l m i n i s t r i e s and d e p a r t m e n t s .

32

Ordere for Agency p u b l i c a t i o n s can be p l a c e d wi th your b o o k s e l l e r or any of our s a l e s a g e n t s l i s t e d be low :

A R G E N T I N A Comis iôn N a c i o n a l de E n e r g i a A t o m i c a A v e n i d a de l L i b e r t a d o r G e n e r a l San Martin 8 2 5 0 B u e n o s A i r e s - Sue . 29

A U S T R A L I A H u n t e r P u b l i c a t i o n s , 23 McKil lop S t r e e t Me lbourne , C . l

A U S T R I A Georg Fromme & C o . S p e n g e r g a s s e 39 A-1050 , V i e n n a V

B E L G I U M O f f i c e i n t e r n a t i o n a l de l ib ra i r i e 30, a v e n u e Marnix B r u s s e l s 5

B R A Z I L L i v r a r i a K o s m o s E d i t o r a Rua do R o s a r i o , 135-137 Rio de J a n e i r o

A g e n d a E x p o e n t e O s c a r M. S i lva Rua Xav ie r de T o l e d o , 1 4 0 - 1 " A n d a r (Ca ixa P o s t a l No. 5 .614) Sao P a u l o

BYELORUSSIAN S O V I E T S O C I A L I S T R E P U B L I C

See u n d e r USSR

CANADA T h e Q u e e n ' s P r i n t e r O t t a w a , Onta r io

C H I N A ( T a i w a n ) B o o k s and S c i e n t i f i c S u p p l i e s S e r v i c e , L t d . , P . O . Box 83 T a i p e i

C Z E C H O S L O V A K S O C I A L I S T R E P U B L I C S . N . T . L . S p o l e n a 51 Nové Mes to P r a g u e 1

D E N M A R K E j n a r Münks gaard L t d . 6 N ö r r e g a d e C o p e n h a g e n К

F I N L A N D A k a t e e m i n e n K i r j a k a u p p a K e s k u s k a t u 2 H e l s i n k i

F R A N C E

O f f i c e i n t e r n a t i o n a l de d o c u m e n t a t i o n e t l i b ra i r i e 48 , rue G a y - L u s s a c P a r i s 5 e

G E R M A N Y , F e d e r a l R e p u b l i c of R . O ldenbourg R o s e n h e i m e r S t r a s s e 145 8 Munich 8

H U N G A R Y K u l t u r a

H u n g a r i a n T r a d i n g Co. for B o o k s and N e w s p a p e r s P . O . B . 149 B u d a p e s t 62

I S R A E L H e i l i g e r and C o . 3 Na than S t r a u s s S t r e e t J e r u s a l e m

I T A L Y A g e n z i a E d i t o r i a l e I n t e r n a z i o n a l e O r g a n i z z a z i o n i U n i v e r s a l i ( A . E . I . O . U . ) Via Meravigl i 16 Milan

J A P A N

Maruzen Company L t d . 6 , Tor i Nichome N i h o n b a s h i ( P . O . Box 605) T o k y o C e n t r a l

MEXICO L i b r a r i a I n t e m a c i o n a l Av. Sonora 206 Mexico 11, D . F .

N E T H E R L A N D S N.V. Mar t inus Ni jhof f L a n g e Voorhout 9 T h e Hague

N E W Z E A L A N D Whitcombe & T o m b s , L t d . G . P . O . Box 1894 Wel l ing ton , C . l

N O R W A Y J o h a n Grundt T a n u m Kar l J o h a n s ga te 43 O s l o

P A K I S T A N K a r a c h i E d u c a t i o n Soc ie ty Haroon C h a m b e r s South N a p i e r R o a d ( P . O . Box No . 4866) K a r a c h i 2

P O L A N D O s r o d e k R o z p o w s z e c h n i a n a Wydawnic tw N a u k o w y c h P o l s k a A k a d e m i e N a u k P a i a c Kul tury i N a u k i Warsaw

R O M A N I A Car t imex Rue A . Br iand 14-18 B u c a r e s t

SOUTH A F R I C A Van S c h a i k ' s B o o k s t o r e ( P t y ) L t d . L i b r i Bu i ld ing Church S t r ee t ( P . O . Box 724) P r e t o r i a

S P A I N L i b r a r i a B o s c h R o n d a de la U n i v e r s i d a d 11 B a r c e l o n a

S W E D E N C . E . F r i t z e s K u n g l . H o v b o k h a n d e l F r e d s g a t a n 2 S tockho lm 16

S W I T Z E R L A N D L i b r a i r i e P a y o t Rue G r e n u s 6 1211 G e n e v a 11

T U R K E Y L i b r a i r i e H a c h e t t e 469 , I s t i k l â l C a d d e s i B e y o g l u , I s t a n b u l

UKRAINIAN S O V I E T SOCIALIST R E P U B L I C

See u n d e r USSR

UNION O F S O V I E T S O C I A L I S T R E P U B L I C S

Mezhduna rodnaya Kniga S m o l e n s k a y a - S e n n a y a 32*34 Moscow G-200

U N I T E D KINGDOM O F G R E A T BRITAIN AND N O R T H E R N I R E L A N D

Her M a j e s t y ' s S ta t ione ry O f f i c e P . O . Box 569 L o n d o n , S . E . I

U N I T E D S T A T E S O F AMERICA N a t i o n a l Agency for I n t e r n a t i o n a l P u b l i c a t i o n s , I n c . 317 E a s t 34th S t ree t New York , N . Y . 10016

V E N E Z U E L A Sr. B rau l i o G a b r i e l C h a c a r e s Gobernador a C a n d i l i t o 37 San t a R o s a l i a (Apar t ado P o s t a l 8092) C a r a c a s D . F .

Y U G O S L A V I A J u g o s l o v e n s k a K n j i g a T e r a z i j e 27 B e l g r a d e

IAEA p u b l i c a t i o n s can a l s o be p u r c h a s e d r e t a i l a t the Uni t ed N a t i o n s B o o k s h o p a t Un i t ed N a t i o n s H e a d q u a r t e r s , New York , a t the n e w s - s t a n d a t the A g e n c y ' s H e a d -q u a r t e r s , V i e n n a , and at mos t c o n f e r e n c e s , s y m p o s i a and s e m i n a r s o r g a n i z e d by the A g e n c y .

In order to f a c i l i t a t e the d i s t r i b u t i o n of i t s p u b l i c a t i o n s , the Agency i s p r e p a r e d to a c c e p t p a y m e n t in U N E S C O c o u p o n s or in l o c a l c u r r e n c i e s .

Orde r s and i n q u i r i e s from c o u n t r i e s whe re s a l e s a g e n t s have not y e t been a p p o i n t e d may be s e n t to :

D i s t r i bu t i on and S a l e s Group , I n t e r n a t i o n a l Atomic Ene rgy A g e n c y , Kärn tne r Ring 11, A-1010 , Vienna I , Aus t r i a

INTERNATIONAL ATOMIC ENERGY AGENCY VIENNA, 1966

PRICE: USA and Canada: US $1.00 Austria and elsewhere: S 21,-(6/ -stg; F.Fr.4,-; DM 3,20)