Neutron transmission and capture measurements for 241 Am at GELINA - - PowerPoint PPT Presentation

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neutron transmission and capture measurements for 241 am
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Neutron transmission and capture measurements for 241 Am at GELINA - - PowerPoint PPT Presentation

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i r f u i r f u i r f u s s s a a a c c c l l l a a a y y y Neutron transmission and capture measurements for 241 Am at GELINA C. Lampoudis, S. Kopecky, A. Plompen, C. Sage P. Schillebeeckx, R. Wynants, O. Bouland, G. Noguere

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Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence

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i r f u y a l c a s i r f u y a l c a s i r f u y a l c a s

Neutron transmission and capture measurements for 241Am at GELINA

  • C. Lampoudis, S. Kopecky, A. Plompen, C. Sage
  • P. Schillebeeckx, R. Wynants, O. Bouland, G. Noguere and
  • F. Gunsing

3rd International Workshop on Nuclear Data Evaluation for Reactor applications September 2012, Aix-en-Provence, France

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Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence

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Outline

Motivation

existing data

GELINA facility

linac experimental setup - sample

Measurements

analysis and results

Summary

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i r f u y a l c a s i r f u y a l c a s i r f u y a l c a s

Motivation

Nuclear waste management: a major pressing and potentially costly environmental problem

Long term radiotoxicity and high volume makes geo-disposal not an

  • ptimum solution

Main components of waste from nuclear reactors

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Resonance parameters for 241Am+n in literature

Capture

– Weston and Todd NSE 61 (1976) 356

ORELA (20 m and 85 m) 1.1 10-4 at/b 241Am, AmO2 + S powder Total energy + WF (C6F6) Ed > 500 keV Normalized at En = 0.0253 eV σγ

th = 582 b

– Jandel et al. PRC 78 (2008) 034609

LANSCE (20 m) 1.7 10-6 at/b 241Am (electroplated on Ti) Total absorption (4π) Mγ = 4 and 3.75 < Eγ

tot < 5.4 MeV

εn,γ = 12.5 ±1.0 % Normalization at 4.9 eV of 197Au(n,γ) ⇒ σγ

th = 665 ±33 b

Transmission

– Derrien and Lucas

Saclay, LINAC (17 m and 53 m) AmO2 (4.5 10-4, 1.6 10-4 , 4.7 10-4 at/b) 10B(n,α1), 478 keV with NaI

– Kalebin et al.

Chopper, AmO2 (3.3 10-3 and 6.3 10-3 at/b) Collimation ~0.8 and 0.4 mm BF3 proportional counters

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Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence

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Literature data

Reference Year σγ(E = 0.0253 eV) Jandel et al. 2008 665 ± 33 Nakamura et al. 2007 690 ± > 24 Fioni et al. 2007 696 ± 48 Maidana et al. 2001 672 ± 10 Shinora et al. 1997 854 ± 58 Evaluation 1982 610 ± 19 Fröhner

0.1 1 10 0.7 0.8 0.9 1.0 1.1 1.2 1.3 (2gΓn)X / (2gΓn)Jandel

Weston and Todd Kalebin et al. Derrien and Lucas

Neutron energy / eV

⇒ Aγ ≈ gΓn for Er = 0.306 eV, 0.574 eV and 1.272 eV ⇒ Transmission: verify normalization of capture data of Jandel et al. and Weston and Todd ⇒ Capture to verify the thermal point and extend the energy range Homogeneous well characterized sample is required

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GELINA facility

F L IG H T P A T H S S O U T H N E U T R O N T A R G E T E L E C T R O N L IN A C F L IG H T P A T H S N O R D

Time-Of-Flight facility Pulsed white neutron source

(10 meV < En < 20 MeV)

Multi-user facility with 10 flight paths

(10 m - 400 m)

The measurement stations have equipment to perform:

Total cross section measurements Partial cross section measurements

Pulse width : 1ns Frequency : 50 – 800 Hz Average current : 4.7 – 75 μA Neutron intensity : 1.6 1012 – 2.5 1013 n/s GELINA: dedicated to

∀ σ(n,tot) ∀ σ(n,f), σ(n,p), … ∀ σ(n,γ)

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GELINA neutron source

NEUTRON MODERATOR ELECTRON BEAMLINE EXIT NEUTRON TARGET NEUTRON FLIGHT PATHS

  • e- accelerated to Ee-,max ≈ 140

MeV

  • (e-, γ) Bremsstrahlung in U-target

(rotating & cooled with liquid Hg)

  • ( γ , n) , ( γ , f ) in U-target
  • Low energy neutrons by water

moderator in Be-canning

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TOF - experiments at GELINA

  • Sample

– AmO2 in Y2O3 matrix (homogeneous) – Purification to reduce 237Np – 40 GBq of 241Am 324.5 mg by γ - spectroscopy 324.6 mg by calorimetry – Ø = 22.14 mm verified by γ - radiography combined with non-contact electronic microscope

  • Transmisson at 25 m

– 6Li-scintilllators

  • Capture at 12.8 m

– Total energy detection – C6D6 detectors + WF – Normalization

Internal : Γn from transmission External : 4.9 eV 197Au+n

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Experimental conditions

Capture and transmission ⇒ gΓn Doppler broadening dominates the observed width for Er > 1 eV Only for low energy resonances Γ can be determined from shape analysis

0.1 1 10 100 10 10

1

10

2

10

3

Γtot

ΔDoppler(292 K) ΔL = 25 m ΔL = 12.5 m

FWHM / meV Neutron energy / eV

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Experiments at GELINA

Measurement Flight path Frequency Filters Overlap Fixed background Additional background Transmission 25 m 50 Hz Co, Bi, Na Ag, Cd 50 Hz Co, Bi, Na, Pb Ag, Cd 800 Hz

10B

Na, Pb Au, W, Co, Mn Capture 12.5 m 50 Hz Co, Bi, Na Cd, Ag, W 400 Hz Cd Bi, Na Ag, W 800 Hz

10B

Na, S, Pb Ag, W, Co

Region Overlap Fixed background filters 50 Hz < 100 eV − Co, Bi, Na 400 Hz > 1 eV Cd Bi, Na 800 Hz > 20 eV

10B

Na, S

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Transmission setup

T exp= Cin− Bin Cout− Bout

Er = 6.6735 ± 0.0030 eV of 238U+n L = 26.444 ± 0.006 m

Li-glass scintillator at 25 m

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Transmission data

10

4

10

5

10

6

10

7

10

  • 2

10

  • 1

10 10

1

10

2

10

3 W Bi Co Ag C

'

  • ut

B

'

  • ut

Response / (1/ns) Time Of Flight / ns

Na

10

4

10

5

10

6

10

7

10

  • 2

10

  • 1

10 10

1

10

2

10

3 W Ag Bi Co Na C

' in

B

' in

Response / (1/ns) Time Of Flight / ns

10

4

10

5

10

6

10

7

0.0 0.2 0.4 0.6 0.8 1.0 1.2 Transmission Time Of Flight / ns

Fixed background filters

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Capture measurements at GELINA

Total energy detection

  • C6D6 liquid scintillators

– 125o – PHWT

  • Flux measurements (IC)

–

10B(n,α)

Y exp= N Cw

' − Bw '

C

' − B ' Y

N C w

' − Bw '

C

' − B ' σ

L = 12.8 m

∫ R( Ed ,Eγ ) WF ( Ed ) dEd=kEγ

Cw(T n)=∫ Cc(T n ,Ed ) WF ( Ed ) dEd

WF : from MC simulations

Borella et al., NIMA 577(2007) 626

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2500 5000 7500 10000 10

  • 4

10

  • 3

10

  • 2

10

  • 1

Counts / (1/keV) Deposited energy / keV

241Am(n,γ) resonances 241Am decay

Pulse height spectra : threshold

Standard

241Am

Ed ≈ 160 keV 650 keV Eγ ≈ 300 keV 850 keV

Choose optimum threshold conditions on detected gamma ray energy due to sample’s activity

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Capture data (counts) for Ed > 650 keV

10

4

10

5

10

6

10

7

10

  • 4

10

  • 3

10

  • 2

10

  • 1

10

C

'

ϕ

B

'

ϕ

Counts / (1/ns) Time-of-flight / ns 10

4

10

5

10

6

10

7

0.0 0.2 0.4 0.6 0.8 1.0 Yield Time-of-flight / ns 10

4

10

5

10

6

10

7

10

  • 4

10

  • 3

10

  • 2

10

  • 1

Na C'

B

' 1

B

' 2

Counts / (1/ns) Time-of-flight / ns

B

' = B ' 1+B ' 2

Co

Time dependent background dominates

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Capture data: impact of threshold

0.01 0.1 1 10 10

  • 3

10

  • 2

10

  • 1

10 Yield Neutron energy / eV 0.1 1 10 100 0.0 0.2 0.4 0.6 0.8 1.0

Ed > 160 keV

Ed > 650 keV

Yield Neutron energy / eV

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Capture and transmission data consistency

0.2 0.4 0.6 0.8 1.0 1.2 1.4

  • 4

4 Residuals Neutron energy / eV 0.5 1.0

Exp.

REFIT ( RP from transmission)

Yield

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Capture and Transmission

0.1 1 10 0.000 0.005 0.010 0.015 0.020 0.025 0.030

Yield [not normalized] neutron energy [eV]

  • exp. data

RSA fit

0.1 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1 10

neutron energy [eV] transmission

  • exp. data

RSA fit

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Conclusions and output

241Am

Transmission and capture data are consistent Characterisation of sample:

Content by calorimetry at JRC/ITU Area by radiography at IRMM

⌠th obtained RP (E, gΓn, , < Γγ>) up to ~ 200 eV Publication to be submitted within October 2012