Fp7 - LEADER Slide 1 ALFRED C&S rods mechanical design C&S_Rods_20121120.ppt Task 3.3 - Primary...

Fp7 - LEADER

Slide 1

ALFRED C&S rods mechanical design

C&S_Rods_20121120.ppt

Task 3.3 - Primary system conceptual design of ALFRED

Control rods & Safety rods

(mech. Design)

The LEADER project

• ALFRED core layout• Basic concepts• C/R design• S/R concept• Status

TOC

F. Manni (S.R.S.)D. Vitale Di Maio (S.R.S.)

LEADER Technical MeetingNovember 20 - 23, 2012Karlsruhe Institut of Technology

Fp7 - LEADER

Slide 2



171 Fuel Assembly

12 Control Rods

4 Safety Rods

108 Dummy Element

ALFRED Core Layout

171

5

Ø 158

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Slide 3



600

Fully extracted

Fully inserted

680

Lead free level (in operation)

373

0

Basic Concepts

Fully extracted

Fully inserted

Diagrid top plane

Control Rod Safety Rod

Core middle plane 40

40

120

120

840

Scram: buoyancyTuning: stepper motor

Scram: gravity + booster

F/A

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Slide 4



Lead Free Level (during operation)

CoreActive zone

C/R S/R

Diagrid

F/ADra

g

Bal

last

Wei

ght

Buo

yan

cy

±20%

Ref

uel

ing

Op

erat

ion

Pre

load

ed

Spr

ing

counteracting buoyancy effects..

±20%

Ballast

Preloaded Springs

Top GridBasic Concepts

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Slide 5



Control Rod design

• Both Control and Scram purposes• Control: absorber pin bundle actuated by stepper motor driven worm gear• Scram: buoyancy driven (upward insertion)• Only electrical connections required

features:

notes:

•The very large gas plenum implies a big buoyancy force and the need for additional ballast which does not fit in the "standard" ballast housing (room found anyway on the top)• Spring press re-designed in order to host worm gear (for actuation) and additional ballast (unification of F/A spring presses required)

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Slide 6



Gas plenum

Reflector

Absorber

C/R design

Lower half

Reflector

Float

Spike

Absorber pin bundle

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Slide 7



Absorber

680

700

275

0

Reflector

Gas plenum(very large!)

134

0

Reflector30

166

158

33

R14,9

6

C/R design

Absorber Bundle layout

33

33

31

166158

1

(from MYRRAH to ALFRED)

Increased peripheral gap

Fp7 - LEADER

Slide 8



nut

solenoid

worm

Control ScramC/R design

Stepper Motor

Float

Actuation

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Slide 9



Ballast

Standard(282 kg)

Additional(83 kg)

C/R: 623 kg

C/R design Due to the very large gas plenum additional ballast is needed to counteract buoyancy

Total mass365 kg

Fp7 - LEADER

Slide 10



C/R design

Spring PressTop Grid

Bellevillewashers

Stepper Motor

Fp7 - LEADER

Slide 11



Preliminary evaluation of the insertion transient

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

4,5

5,0

0,000 0,200 0,400 0,600 0,800 1,000 1,200

Acce

lera

tion

[m |

s2 ]

Time [ s ]

Acceleration vs Time

0,00

0,10

0,20

0,30

0,40

0,50

0,60

0,70

0,80

0,000 0,200 0,400 0,600 0,800 1,000 1,200

Spac

e [m

]

Time [s]

Space vs Time

•Lead flow and stopping time impacts on the insertion time are not considered in the preliminary evaluation. •A preliminary insertion time of about 0.85 s has been estimated; considering the negative acceleration for the arrest, the insertion time is longer but should be shorter than 1 s.

C/R design

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Slide 12



Safety Rod concept

• Just scram, not regulation• Scram: gravity driven (downward insertion)• pneumatic booster system needed to speed up insertion• Electrical and Pneumatic connections (Hi and Lo pressure lines) required

features:

notes:

• Very small gas plenum (reduced buoyancy problems)• Structural design and interfaces similar to C/R and F/A

Fp7 - LEADER

Slide 13



Absorber

6084

0

1080

Reflector

6060 Reflector

S/R Concept

Very small Gas plenum (not necessary)

Reduced buoyancy

Provisional Layout!

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Slide 14



A1 A2<< >

A1' A2

D

d

F1 < F2 (P1 • A1 < P2 • A1)

F1 >> F2 (P1 • A1 >> P2 • A1)

P1

P2F1

F2

F1

F2

Low pressure chamber

High pressure chamber

Metering pin

Thrust piston

Thrust column

Housing

Orifice

Booster

Adaptation of a proven concept used for automotive safety tests (HyGe sled)

Fp7 - LEADER

Slide 15



P1P2

Sol 1 Sol 2 Sol 3 Sol 4 Sol 5 Sol 6D 140 120 100 140 120 100 [mm]

d 20 20 20 20 20 20 [mm]D/d 7 6 5 7 6 5 [ ]

P1 200 200 200 100 100 100 [bar]P2 min 4.2 5.7 8.3 2.1 2.9 4.2 [bar]

P2 5 10 10 3 5 5 [bar]dp/P2min 20% 75% 20% 44% 75% 20% [ ]

F1 628 628 628 314 314 314 [kgf]F2 754 1100 754 452 550 377 [kgf]

F2-F1 126 471 126 138 236 63 [kgf]

F1' 30788 22619 15708 15394 11310 7854 [kgf]

F1'-F2 30,034 21,520 14,954 14,941 10,760 7,477 [kgf]

By playing with inner diameter and pressures, a wide range of performance can be attained.

D dP1 P2

The shape of the metering pin determine the acceleration profile.

burstburst ramp long ramp

Booster

Fp7 - LEADER

Slide 16



P1P2

B C

D

A

Active mode:

Solenoid "A", valves "A" and "B" (both normally open) are electrically actuated.De-energizing any (or all) of them will cause depressurization (i.e. "shot" initiation)

Passive mode:

•Loss of electrical supply see above•Low pressure line break see above•High pressure line break causes the mechanical actuation of the Valve "C"

low chamber depressurization is the basic event (but not the only one) which can trigger the device

•The system does not relay on the efficiency of the gas reservoirs or of the feeding lines.•due to the small diameter of the high pressure line, in case of rupture, a significant depressurization of the high pressure chamber occurs after a very long time, therefore enough boosting force is available for scram (caused by automatic actuation of valve "C")

Low pressure line

High pressure line

Booster

Fp7 - LEADER

Slide 17



www.hyge.com

Booster

Fp7 - LEADER

Slide 18



Status

• C/R mechanical design reports (some amendments needed)• S/R concept

• Unification of F/A, C/R and S/R interfaces • C/R drawings• S/R mechanical design & drawings

done

to do

• 1 month completion time

Fp7 - LEADER Slide 1 ALFRED C&S rods mechanical design C&S_Rods_20121120.ppt Task 3.3 - Primary...

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