20F POWER MEASUREMENT FOR GENERATION IV SODIUM FAST

REACTORS

R. Coulon, S. Normand, M. Michel, L. Barbot, T. Domenech, K. Boudergui, J-M Bourbotte, V. Kondrasovs, A-M. Frelin-Labalme, H. Hamrita, G. Ban, E. Barat, T.

Dautremer, T. Montagu, F. Carrel, H-P Brau, V. Dumarcher, J-L Portier, P. Jousset, N. Saurel

CEA, LIST, Laboratoire Capteurs et Architectures Electroniques,F-91191 Gif-sur-Yvette, France.

European Nuclear ConferenceTuesday, June 2nd 2010

1. Introduction

Delayed γ spectrometry measurement Alternative for real time estimation of the power

magnitude Activation products have a high fission rate

representativeness ADONIS system : high metrological grade in high

count rate and in fluctuating situations

Sodium Fast Reactor power measurement Neutron measurement (real time estimation but

no accuracy) Heat balance measurement (accurate

measurement ; periodically used to set the nominal operating point)

The Phénix reactor

The ADONIS electronics

23 1 24 23

23 1 23 1 23

23 1 20 4 20

23 1 22 1 22

40 1 41 41

2

e

e

e

e

e

Na n Na Mg

Na n Ne p Na

Na n F Ne

Na n Na n Ne

Ar n Ar K

Neutron activation products

2. Activation products

Delayed gamma

T1/2=15h E=1.37&2.75MeV

T1/2=23s E=440keV

T1/2=11s E=1.63MeV

T1/2=2y E=1.28MeV

T1/2=1.8h E=1.29MeV

Sodium coolant activation

3. Model for delayed gamma spectrometry on SFR

1. In-core activation based on nuclei balance: Nuclear data Neutron spectrum Velocity, flow rate, temperature and

neutron flux profile

2. Build-up and transit model: Coolant cycle time Dilution function

Transit time

3. Gamma transport and pulse high tally simulation using MCNP code:

Germanium diode RX radiography

Simulated γ spectrum

4. How to obtain a real time power measurement?

The response time is composed of 2 integration times:

1. A physical integration time due to the build-up transient stage

2. A statistical integration time due to the 24Na Compton background noise and Poisson process of the counting measurement

4.1 Physical integration timeC

on

cen

tra

tion

(cm

-3)

Time (s)

2 candidates:The fluorine 20

T1/2=11 s

Build-up rate =0.01% Transient time=70 s

The neon 23 T1/2=23 s

Build-up rate =5.2% Transient time=4 min

Requirement : Use of a short decay period tagging agent

Use of a high gamma energy emitter Fluorine 20: 1.634 MeV Neon 23: 440 keV

Use a short transit time to measurement sample

Use of a high count rate and high energy resolution spectrometry system Hyper-Pure Germanium diode Adaptive ADONIS γ pulse analyser

4.2 Statistical integration time

20F Direct measurement on sodium23Ne Measurement after a degassing stage

teSS

S

eS

FWHMBt

T

T

S

S

.

.

.

1

.

.8,8

E. Barat & Al. Nucl. Instr. A 567 (206) 350-352

1,0E-05

1,0E-04

1,0E-03

1,0E-02

1,0E-01

0 10 20 30 40 50 60 70 80 90 100

Response time (s)

P/P

N

20F power measurement

23Ne power measurement (440 keV)

6. Power dynamic range vs. response time

Pseudo-optimal configuration :

5 s of transit time and using the High count rate abilities ADONIS system

0

1

2

3

4

5

6

7

4 5 6 7 8 9 10

Response time (s)

Me

asu

rem

ent

erro

r (%

)

20F power measurement

23Ne power measurement

6. Statistical accuracy vs. response time

Pseudo-optimal configuration :

5 s of transit time and using the High count rate abilities ADONIS system

Transittime

Phénix primary Na spectrumat 50 MW thermal power

1,00E-05

1,00E-04

1,00E-03

1,00E-02

1,00E-01

1,00E+00

1,00E+01

0 500 1000 1500 2000 2500 3000 3500 4000 4500

Energy (keV)

Co

un

t ra

te (

Cp

s)5. 20F measurement at the Phénix reactor

May, 21st

Pb & Cu RX peaks

Annihilation peak

20F peak at 1.634 MeV

24Na peak at 1.369 MeV

24Na peak at 2.754 MeV

Escape peaks

6. Phénix power measurement

0,0E+00

5,0E-04

1,0E-03

1,5E-03

2,0E-03

2,5E-03

3,0E-03

3,5E-03

4,0E-03

10:30 11:42 12:54 14:06 15:18 16:30 17:42 18:54 20:06

Time

S2

0F

/P (

c.M

J-1

)

P=302 MWth

P=308 MWth

P=335 MWth

P=337 MWth

Reactor shutdown to

14 MWth

Power increase

7. Experimental results for 20F

Linearity with power

---Non-optimal accuracy

due to the configuration of the test

Comparison of 20F signal vs. accurate thermal balance measurement

P=302 MWth

P=308 MWth

P=335 MWth

P=337 MWthCumulative effect

Power increase=

Na Temperature & flow rate

effectsReactor shutdown

=High cumulative effect

impact

P=14 MWthS24Na/P=9±1

0,36

0,37

0,38

0,39

0,40

0,41

0,42

10:30 11:42 12:54 14:06 15:18 16:30 17:42 18:54 20:06

Time

S2

4N

a/P

(c

.MJ

-1)

8. Experimental results for 24Na

Comparison of 24Na signal vs. accurate thermal balance measurement

9. Accuracy limitation of the method

During power increasing Flow rate and temperature changes induce distortion (shown in Phenix test)

In nominal operating Flow rate and temperature are stable Breeding and burn-up could potentially induce distortion by neutron

spectrum hardening? (other data analysis are in process)

10. Perspectives

23Ne and 20F dual analysis could be a solution to correct theses distortions as well for temperature and flow rate distortion and as well for burn-up and breeding potential distortion

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0 0,2 0,4 0,6 0,8 1

Relative sodium velocity

Re

lati

ve

S2

0F

/S2

3N

e s

en

sib

ility

0,0E+00

5,0E+09

1,0E+10

1,5E+10

2,0E+10

2,5E+10

0 2 4 6 8 10 12 14 16 18 20

Energy (MeV)

Rea

ctio

n r

ate

(cm

-3.s

-1)

23Na(n,alpha)20F23Na(n,p)23Ne

11. Conclusion

Tagging agents 20F measurement on sodium coolant sample 23Ne measurement after a degassing stage

System Sampling at the reactor core outlet Short transit time High count rate gamma spectrometry analyzer (ADONIS)

Other simulations and experimental studies have to be done : Build-up phenomenon Burn-up and breeding impact Multi-gamma analysis

Delayed gamma power measurement for SFR could be an alternative to neutron measurement for real time power monitoring

To be continued.

Thanks for your attention