REFERENCE 166 - ncsp.llnl.gov
Transcript of REFERENCE 166 - ncsp.llnl.gov
REFERENCE 166
“NUCLEAR CRITICALITY SAFETY CRITERIA FOR STEEL-PIPE INTERSECTIONS CONTAINING AQUEOUS SOLUTIONS OF FISSILE MATERIALS,” ANSUANS-8.9- 1987 (AMERICAN NATIONAL STANDARDS INSTITUTE, INC., NEW YORK, 1987).
nuclear criticality safety criteria for steel-pipe intersections containing
aqueous solutions of fissile material
ANSVANS-8.94 987 Revision of
ANSIIANS-8.94 978
American National Standard Nuclear Criticality Safety Criteria for Steel-Pipe Intersections
Containing Aqueous Solutions of Fissile Materials
Secretariat American Nuclear Society
Prepared by the American Nuclear Society Standards Committee Working Group ANS4.9
Published by the American Nuclear Society 555 North Kensington Avenue La Grange Park, Illinois 60525 USA
Approved April 3, 1987 by the American National Standards Institute, Inc.
American Designation of this document as an American National Standard attests that the
National principles of openness and due process have been followed in the approval procedure and that a consensus of those directly and materially affected by the standard has
Standard been achieved.
This standard was developed under the procedures of the Standards Committee of the American Nuclear Society; these procedures are accredited by the American National Standards Institute, Inc., as meeting the criteria for American National Standards. The consensus committee that approved the standard was balanced to assure that competent, concerned, and varied interests have had an opportunity to participate.
An American National Standard is intended to aid industry, consumers, govern- mental agencies, and general interest groups. Its use is entirely voluntary. The existence of an American National Standard, in and of itself, does not preclude anyone from manufacturing, marketing, purchasing, or using products, processes, or procedures qot conforming to the standard.
By publication of this standard, the American Nuclear Society does not insure anyone utilizing the standard against liability allegedly arising from or after its use. The content of this standard reflects acceptable practice at the time of its ap- proval and publication. Changes, if any, occurring through developments in the state of the art, may be considered at the time that the standard is subjected to periodic review. It may be reaffirmed, revised, or withdrawn at any time in accord- ance with established procedures. Users of this standard are cautioned to deter- mine the validity of copies in their possession and to establish that they are of the latest issue.
The American Nuclear Society accepts no responsibility for interpretations of this standard made by any individual or by any ad hoc group of individuals. Requests for interpretation should be sent to the Standards Department at Society Head- quarters. Action will be taken to provide appropriate response in accordance with established procedures that ensure consensus on the interpretation.
Comments on Headquarters.
this standard are encouraged and should be sent to Society
Published by
American Nuclear Society 555 North Kensington Avenue, La Grange Park, Illinois 60525 USA
Copyright 0 1987 by American Nuclear Society.
Any part of this standard may be quoted. Credit lines should read “Extracted from American National Standard ANWANS-8.9-1987 with permission of the publisher, the American Nuclear Society .” Reproduction prohibited under copyright convention unless written per- mission is granted by the American Nuclear Society.
Printed in the United States of America
Foreword (This Foreword is not a part of American National Standard Nuclear Criticality Safety Criteria for Steel-Pipe Intersections Containing Aqueous Solutions of Fissile Materials, ANSUANS-8.9-1987.)
Basic parameters and practices for nuclear criticality control outside reactors are described in American National Standard for Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors, ANSI/AN%8.14983, and in documents referenced therein. However, for the most part, the data in that standard are single parameter limits.
In the past there has been a paucity of experimental and calculated data for geometric arrangements, such as crosses, ells, and tees, for storage and processing of aqueous solutions of fissile materials in pipes. This situation resulted in overly conservative applications which became evident soon after Work Group 8.9 undertook the drafting of a standard on this subject in 1968. Over the succeeding years, additional experimen- tal data and advanced computational technology became available and now provide the means to reduce the conservatism in industrial practice and permit greater flex- ibility in process applications. The American National Standard Nuclear Criticality Safety for Pipe Intersections Containing Aqueous Solutions of Enriched Uranyl Nitrate, ANSUANS-8.9-1978, has been extended to include typical aqueous solutions of fissile materials and, in particular, uranium containing no more than 5 wt% 235U. Accept- able configurations are presented as standard schedule pipe sizes for a variety of parameters.
In order to facilitate the applicability of this standard allowances have been made for situations which cannot be known or controlled absolutely. The specifications given in this standard are based upon validated calculations in which consideration of an adequate margin of subcriticality included variations in chemical concentrations (kern ry 0.03), a bias in calculations of solution systems (ken ry 0.021, the influence of container materials (keff hr 0.05), and a minimum margin of subcriticality (keff - 0.05). Thus, the systems as specified have a nominal keff of 0.85. Submerged intersections have a nominal keff of 0.90. Generally, fissile and other materials will be present in addi- tion to aqueous fissile solutions contained in piping. It will be necessary for a safety specialist to evaluate their reactivity contribution to proposed pipe intersections in order to confirm compliance with requirements of the standard. It would be unusual for a design not to require review by a safety specialist.
This standard was prepared by Work Group ANS-8.9, under the guidance of American Nuclear Society Standards Subcommittee 8. The Work Group, chaired by 3. T. Thomas, was comprised of the members of the Subcommittee 8 and J. E. Bigelow, Oak Ridge National Laboratory.
The membership of Subcommittee 8, Fissionable Materials Outside Reactors, at the time of preparation and approval of this revision was:
J. T. Thomas, Chairman, Martin Marietta Energy Systems, Inc. E. B. Johnson, Secretary, Oak Ridge National Laboratory F. M. Alcorn, Babcock and Wilcox Company H. K. Clark, Savannah River Laboratory E. D. Clayton, Battelle Pacific Northwest Laboratories D. M. Dawson, Battelle Memorial Institute M. C. Evans, British Nuclear Fuels plc N. Ketzlach, U. S. Nuclear Regulatory Commission R. Kiyose, University of Tokyo W. G. Morrison, Exxon Nuclear Zdaho Co., Inc. (Retired) D. R. Smith, Los Alamos National Laboratory G. E. Whitesides, Martin Marietta Energy Systems, Inc. F. E. Woltz, Goodyear Atomic Corporation
Consensus Committee N16, Nuclear Criticality Safety, which reviewed and approved this standard in 1985, had the following membership:
Dixon Callihan, Chairman E. B. Johnson, Secretary
AlexF.Perge ........................................ American Institute of Chemical Enginers Dixon Callihan .................................................... American Nuclear Society Ricardo Artigas ........................ American Society for Testing and Materials (Liaison only) D. Frank Cronin ................................................... .Atomic Industrial Forum Leo E. Hansen ................................................. Exxon Nuclear Company, Inc. Representative not Assigned. ........................................... Health Physics Society C. Leslie Brown .................................... Institute of Nuclear Materials Management William T. Mee, alt. William R. Waltz ................................................. Savannah River Laboratory Blake P. Brown. .................................................. U.S. Department of Energy George H. Bidinger ....................................... U.S. Nuclear Regulatory Commission Elizabeth B. Johnson, Individual Hugh C. Paxton, Individual Fred W. Sanders, Individual
Contents SeCtion Page
1. Introduction ...................................................... ..l
2. Scope ............................................................ ..l
3. Definitions ....................................................... ..l 3.1 Limitations .................................................... .l 3.2 Shall, Should, and May ........................................... 1 3.3 Glossary of Terms ............................................... 1
4. Nuclear Criticality Safety Practices ................................... .2
5. Specifications for Pipe Intersections ................................... .2 . 5.1 Reflector
5.2 Aqueous 5.3 Aqueous 5.4 Aqueous
Conditions..............................................2 Uranium Solutions. ..................................... .2 Plutonium Solutions .................................... .3 233USolutions .......................................... .
6. Application of Criteria .............................................. .3
7. References.. ....................................................... .
Tables ................................................................
Table1 ......................................................... ...5 Table 2 ......................................................... ...6 Table 3 ......................................................... ...7 Table4 ......................................................... ...7
Figures .............................................................. .
Fig. 1 Area of Intersection .......................................... .4 Fig. 2 Intermediate Reflector Condition ............................... .4 Fig. 3 Partial Reflection. ........................................... .4 Fig. 4 Prohibited Quadrant for Intermediate
Reflector Condition .......................................... .4
Nuclear Criticality Safety Criteria for Steel-Pipe Intersections Containing Aqueous Solutions of Fissile Materials
1. Introduction
This standard provides criteria and data based on criticality experiments and validated calcula- tions’-’ which are generally applicable to homo- geneous aqueous solutions of fissile materials. It includes specific information on fissile solutions containing uranium highly enriched in the 235U or 233U isotope, lutonium, and uranium solu- tions having a 23& content not exceeding 5 wt% of the total uranium.
2. Scope This standard is applicable to the storage, trans- fer, and processing of homogeneous aqueous solu- tions of uranium and plutonium in intersecting schedule 10, or heavier, steel pipes. No informa- tion is included on specific chemical and mechan- ical technology, on fluid dynamics, or on other engineering fundamentals also required in safe design of process equipment.
3. Definitions
3.1 Limitations. The definitions given be1 .ow are restricted to the purposes of this standard. Other
1J. T. Thomas, “Reflectors, Infinite Cylinders, Intersecting Cylinders, and Nuclear Criticality,” Nucl. Sci. Eng., 67,279 (1978). 2N. F. Cross, G. E. Whitesides, and R. J. Hinton, “Monte Carlo Analysis of Experimentally Critical Pipe Intersections,” Trans. Am. Nucl. Sot., 17, 268 (1973).
Qeanne Dickinson, “Calculations for Pipe Intersections Con- taining Fissile Solution, ” RFP-1499, Dow Chemical U.S.A., Rocky Flats Division (1970). 4B. B. Ernst and C. L. Schuske, “Empirical Method for Calculating Pipe Intersections Containing Fissile Solutions,” RFP-1197, Dow Chemical U.S.A., Rocky Flats Division (1968).
55. K. Fox, L. W. Gilley, and D. Callihan, “Critical Mass Studies, Part IX, Aqueous 235U Solutions,” ORNL-2367, Oak Ridge National Laboratory (1958). SE. B. Johnson, “The Nuclear Criticality of Intersecting Cylinders of Uranyl Fluoride Solutions,” Y-DR-129, Oak Ridge Y-12 Plant (1974).
specialized terms are defined in the Glossary of Terms in Nuclear Science and Technology [1].7
3.2 Shall, Should, and May. The word “shall” is used to denote a requirement, the word “should” to denote a recommendation, and the word “may” to denote permission, neither a re- quirement nor a recommendation. To conform with this standard, all operations shall be per- formed in accordance with its requirements but not necessarily with its recommendations.
3.3 Glossary of Terms
area of intersection. The area of the solution within an arm which intersects a plane tangent to the column at the point where the axis of the arm intersects the surface of the column. (See Fig. 1.)
arm. Any pipe intersecting a column.
column. The pipe of largest diameter in a system of intersecting pipes.
environmental factors. Conditions of the envi- ronment, usually not directly related to the pro- cess, that may affect the margin of subcriticality of a system and that could be subject to change.
full reflector. A closely fitting, effectively infi- nite thickness of water, or its equivalent, sur- rounding the system of pipes.
intermediate reflector. A neutron reflector that contributes reactivity to a column with intersect- ing arms not exceeding that reactivity corre- sponding to the presence of a concrete wall in con- tact with the column and arms in a 2-m-square room having 30-cm-thick concrete walls and floor. (See Fig. 2.)
7Numbers in brackets tion 7, References.
refer to corresponding numbers in Sec-
American National Standard ANSVANS-8.9-1987
partial reflector. A neutron reflector that contri- butes reactivity to a column with intersecting arms not exceeding that reactivity corresponding to the presence of a 2-m-square room having 30-cm-thick concrete walls and floor, in which the fissile material is more than 30 cm from any con- crete surface. (See Fig. 3.)
nuclear criticality safety. Protection against the consequences of an inadvertent nuclear chain reaction, preferably by prevention of the reaction.
quadrant. The region on the surface of a section bounded by any two perpendicular planes in- tersecting along the axis of the section.
section. Any arbitrary 0.5-m length of a column.
validated computational technique. A calcula- tional method that satisfies the requirements in American National Standard for Nuclear Criti- cality Safety in Operations with Fissionable Ma- terials Outside Reactors, ANWANS-8.1-1983 [2].
4. Nuclear Criticality Safety Practices
Operations within the scope of this standard shall be conducted in accordance with American Na- tional Standard for Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors, ANSI/ANS-&l-1983. Section 4 of ANS-8.1 discusses administration and technical practices to be followed, and the Appendix lists some credi- ble abnormal operating conditions that should be considered. This standard supplements ANS-8.1 by providing acceptable configurations for pipe in- tersections containing homogeneous aqueous solu- tions of fissile materials. All dimensions shall be interpreted as nominal values of schedule 10 or heavier standard steel pipe. Only single columns with intersections are considered in this standard. Multiple columns or columns in the vicinity of other fissile materials and the influence of their environmental factors shall be investigated by experiment or by a validated computational tech- nique. It is emphasized that appropriate precau- tions to help assure quality in installation and operation of equipment and for control of moder- ators and of nearby fissile materials shall be established to prevent the invalidation of any of the stipulated parameters upon which nuclear cri- ticality safety is dependent.
5. Specifications for Pipe Intersections
Acceptable pipe intersections utilizing standard schedule 10, or heavier, steel pipe are presented in Tables 1 through 4 for several fissile materials and neutron reflector conditions.8 Since no limit is imposed on the length of a column or on the number of sections containing arms, a column containing an unlimited number of sections would be subcritical.
5.1 Reflector Conditions. Specifications for pipe intersections shall be made on the basis of the reflector condition. Selection of the reflector condition for a column shall be based upon an evaluation of its location and on environmental factors.
5.1.1 Sections shall meet the appropriate specifications of dimensions, quadrants per sec- tion permitted to contain arms, and number of arms per quadrant presented in Tables 1 through 4 for the selected reflector condition.
5.1.2 A column located a distance of 30 cm or less from a wall shall satisfy the intermediate reflector specifications.
5.1.3 Arms shall not intersect a column, under the intermediate reflector condition, in the quad- rant bisected by a plane containing the column axis and the shortest distance from the column surface to the wall (see Fig. 4).
5.1.4 Full-reflector specifications shall be ap- plied to a column that is either submerged or that has hydrogenous materials between the arms.
5.1.5 A column located a distance of more than 30 cm from a wall should satisfy the partial reflec- tor condition.
5.2 Aqueous Uranium Solutions. The specifi- cations of Tables 1 through 3 apply to uranium of any 2WJ content in aqueous solutions, provid- ed that the 233U content does not exceed 1 wt% of the uranium content. The specifications of Table 4 may be used in lieu of Tables 1 through 3 for uranium solutions in which the 2WJ con- tent of the uranium does not exceed 5 wt%, and the 233U content of the uranium does not exceed 0.05 wt% of the total uranium.
spipe intersections meeting the reflector conditions of Tables 1 through 4 were evaluated by the method described in the reference of Footnote 2 and had neutron multiplication fac- tors not exceeding 0.85 for the partial and intermediate reflec- tor conditions and not exceeding 0.90 for the full reflector.
2
American National Standard ANSI/ANS-8.9-1987
5.3 Aqueous Plutonium Solutions. The specifi- cations of Tables 1 through 3 shall apply to aque- ous solutions of plutonium not exceeding a con- centration of 400 g Pu/L. The a% content of the plutonium shall not exceed the 240Pu content.
5.4 Aqueous mu Solutions. The specifications df Tables 1 through 3 shall apply to aqueous solu- tions of uranium or thorium havin tion of 233 U not exceeding 500 g B
a concentra- 33U/L.
6. Application of Criteria
Appropriate to the fissile material and evaluated reflector condition of a column, the following re- quirements shall be verified for pipe intersections to which the specifications of Tables 1 through 4 are applied.
6.1 The reactivity contribution to a column from environmental factors in process operations shall be confirmed not to exceed the contribution of the selected reflector condition.g Pipe dimensions should be selected to satisfactorily compensate for possible changes in reflector conditions.
6.2 The maximum area of intersection per quad- rant, i.e., the sum of the areas intersected by all arms, specified in Tables 1 through 4 shall not be exceeded. The tabulations represent orthogonal intersections. The angle between column and arm
axes may range between 30 and 90 degrees. It may be necessary to reduce the number of arms per quadrant or, in the case of a single arm, to reduce the arm diameter in order to satisfy the specified maximum permissible area of intersection.
6.3 Regardless of the total area of intersection in a quadrant, the specified number of arms per quadrant in the Tables shall not be increased.
6.4 The minimum separation of multiple arms within a quadrant shall be no less than the separation of the maximum permissible number when equally spaced. This separation shall not be reduced for continued extension of arms.
7. References
[l] American National Standard Glossary of Terms in Nuclear Science and Technology, Nl.l-1976 (ANS-9). American Nuclear Socie- ty, LaGrange Park, IL.
[23 American National Standard for Nuclear Cri- ticality Safety in Operations with Fissionable Materials Outside Reactors, ANWANS-8. l- 1983. American Nuclear Society, LaGrange Park, IL.
Only the standards explicitly referred to in this document qualify as references. Subsequent revi- sions of these standards shall not be substituted.
The system should have a k,u < 0.85 for the partial and in- termediate reflector condition, and d 0.90 for the full reflec- tor condition.
3
Reflector wall uadr axia
ant
I , I #C’ N I ' I
=‘,8'
s?' ' e
$6 I * Area of intersection I ’ I ' - . * Plane tangent to I
I column surface I I I 9 Column I I I
Column axh
Fig. 1. Area of intcr8ection
Concrete v
230 cm
CT
w--w
*0.3 In
r -c-s I I I I I I I I I .
+2m+ I I
Pig. 3. Partial reflection
- -s
I
2m
I --
Fig. 2. Intermediate reflector condition
Concrete
Column
1 0.3 m
a m e
I
2m
I --
+2m+ I I
r Reflector wall
Shortest distance
Bisecting plane
Area of intersection
Tangential plane
Fig. 4. Prohibited quadrant for intermediate reflector condition
Table 1. Specifications for Steel Pipe Intersections Containing Aqueous Solutions of Uranium or Plutonium in Standard Schedule 10 Pipe Under Partial Reflector Conditions
Maximum permissible 235~8 or 239pUb 233uc
Maximum permissible
area of intersection
per arm (cm21
235~1 or 230pub 233~~
Permissible number of Standard pipe schedule 10 or
heavier. Nominal size (in.)
wlumn arm
Standard pipe schedule 10 or
heavier. area of 1 Permissible number of 1 Permissible number of Permissible number of
quadrants arms per per section quadrant with arms
intersection quadrants per section witb arms
arms per quadrant
quadrants per section with arms
quadrants per section with arms
arms per quadrant Nominal size (in.)
l-i arm
6 4 3
2.5
2
1.5 5 5
4
3.5
3
2.5
2
4 4
3.5
3
per arm (cm21
91.94 1 1 4 2.5 35.16 1 4
5 3
1 4 2 3 3 2
53.87
35.16
1 2
2 1
2 23.55 1 4 4 3 I 3 1 2 3
2 1 1
1.5 5 3 2 1
1 2 3
3 2 1
3.5 3.5 1 2 3
3 2 1
23.55
3 53.87 1 1 4 3 2
2 4 3 2 4 1 1 3 4 4 2 3 4 4 2
14.32 4 1 3x-++ 142.06 1 1 4 3
2.5 91.94 1 3
2 1
1 1 I I
2 1
3 2 1 2
4 3 2 1
3 2 3 2
23.55 I
1 4
5 4
2 71.61 1 2 4
3 2 1
1 2
1.5 5
+
++-
53.87 2 3 4
3 2 1
1 2 3
3 3 3
2.5
2
1.5 2.5 2.5
3 2
3 4 3
35.16 3 4
35.16 3 4
23.55 4
1 14.32 4 , 35.16 4 , 23.55 4
23.55 4 2 1 3
4
1 2
5 4 ~~ I 5 91.94 1 2 3
3
~ : 4 4 I 4
2 5 4 I 5 2 3
3 2 I- 3 2
1 2
71.61 1.5 14.32 4 5 4 5
53.87 3 4
2 3
1 I
*Aqueous uranium solutions: applicable to any 23sU content of the uranium, provided the 233U content does not exceed 1 wt% of the total uranium. bAqueous plutonium solutions: applicable to plutonium concentrations not exceeding 400 g/L and containing more 2’?% than 241Pu.
‘Aqueous solutions of uranium or thorium: applicable to any 233U content not exceeding 500 g 233U/L.
Table 2. Specifications for Steel Pipe Intersections Containing Aqueous Solutions of ranium or Plutonium in Standard Scheduled 10 Pipe Under’ Intermediate Reflector Conditions U
I
Permissible number of
Maximum permissible
area of Standard pipe schedule 10 or
235~1 Or 239pUb
Permissible number of intersection
per arm (cm21
quadrants arms per per section with arms
I I
quadrants quadrantd per section
with arms Nominal size (in.)
column II column 1 arm 1 (cm2) 1 with arms 1 I
with arms I
arm
4 L I 1
3.5 3.5 71.61 1 3 1 ! 2 2 2 2 1 3 1 ,
3 53.87 1 4 1 3 2 3 2 2 3 II I I I I 2 I 3 I 1
5 3.5 71.61
3 53.87
2.5 2 3
-3 3
3
4 3
-4 3
3
35.16 : I : I
2 23.55 1 3 1 2 1 4 4 91.94
: I : I 3.5 il.61
3 3
2.5
2
53.87 2 3 3 2
I I 35.16 3 4
23.55 3 4
+
3 53.87 I 1 I 4 3 3
I 1 2
2.5 35.16 1 5 1 3 4 3
23.55 3 4 2 3
14.32 3 4 2 3
2
1.5 2.5 2.5 35.16 3 3 2 4
2 23.55 3 3 3 4
‘Aqueous uranium solutions: applicable to any 23sU content of the uranium, provided the 233U content does not exceed 1 wt% of the total uranium.
bAqucous plutonium solutions: applicable to plutonium concentrations not exceeding 400 g/L and containing more 2?u than 241Pu.
CAqucous solutions of uranium or thorium: applicable to any 233U content not exceeding 500 g 233U/L.
dNote 5 1.3 and Fig. 4 for prohibited quadrants. .
American National Standard ANSUANS-8.9-1987
Table 3. Specifications for Steel Pipe Intersections Containing Aqueous Solutions of Uranium or Plutonium in Standard Schedule 10 Pipe Under Full Reflector Conditions
Maximum permissible
area of intersection
per arm (cm21
235~s or 239pUb 233~~
Permissible number of Permissible number of Standard pipe schedule 10 or
heavier. Nominal size (in.)
quadrants per section with arms
-- 1 1 2 3 4
--
2 3 4
4 --
arms per quadrant
--- I I I 1 I
1 1 1
1
column I arm
91.94 71.61 53.83 35.16 23.55
I 71.61 53.87 35.16
----
53.87
4 1 4 I 4 I
3 I
3 4
‘Aqueous uranium solutions : applicable to any 235U content of the uranium, provided the 233U content does not exceed 1 wt% of the total uranium.
bAqueous plutonium solutions : applicable to plutonium concentrations not exceeding 400 g/L and containing more ‘%A than “‘Pu.
‘Aqueous solutions of uranium or thorium: applicable to any 233U content not exceeding 500 g ‘33U/L.
Table 4. Specifications for Steel Pipe Intersections Containing Aqueous Solutions of Uraniuma with Maximum 235U Content of 5 wt%
Full reflector Number of
Parti reflector Number of
Intermedia le reflector Number of
Standard pipe schedule 10 or heavier.
Nominal size (in.) -- column arms
Maximum permissible
area of intersection
per arm (cm2)
IO 10 550.32
8 351.61
6 204.52
5 142.06
8 8 351.61
6 204.52
quadrants- per section with arms
quadrants per section with arms
arms per quadrant
arms per quadrant
‘The 233U content of the uranium shall not exceed 0.05 wt%.
bNote 5 1 3 and Fig. 4 for prohibited quadrants. . .
0
1
I
1
1
1 --
2 1
3 I
3 I
3 I
3 1 L