The choice of Pu242 fission chambers to monitor the fast neutrons in a high flux

Philippe Filliatre; Ludovic Oriol; Christian Jammes; Ludo Vermeeren; Marcel Wéber

The choice of Pu242 fission chambers to monitor the fast neutrons in a high flux

Philippe Filliatre, Ludovic Oriol, Christian Jammes, Ludo Vermeeren, Marcel Wéber

Research output › peer-review

Abstract

Fission chambers are widely used for on-line measurements of neutron fluxes in irradiation reactors. When the flux is high with a significant thermal component, the measurement of the fast component is a concern and implies a careful choice of the deposit material. Indeed, most fissile materials have a cross section much higher with thermal neutrons than with fast ones. Moreover, a deposit chosen to favour fissions by fast neutrons will make radiative captures in the thermal domain, leading to a gradual modification of the isotopic compositions of the deposit that may dramatically increase the fissions with thermal neutrons. Within the framework ot the FNDS (Fast neutron Detector System) project, we performed simulations of the evolution of the isotopic composition and fission rate for several deposits under high fluxes. We show that Pu242 is the best choice to extract the fast component from a flux with a significant thermal component, provided that the impurities in Pu241 and Pu239 are small enough. However, an independent measurement of the thermal component appears to be necessary to compensate for the evolution of the Pu242 deposit.

Original language	English
Title of host publication	Proc. NPIC&HMIT 2009
Place of Publication	La Grange Park, Illinois, United States
State	Published - Apr 2009
Event	Sixth American Nuclear Society International Topical Meeting on Nuclear Plant Instrumentation, Control and Human-Machine Interface Technologies (NPIC&HMIT2009) - ANS, Knoxville, Tennessee Duration: 5 Apr 2009 → 9 Apr 2009

Conference

Conference	Sixth American Nuclear Society International Topical Meeting on Nuclear Plant Instrumentation, Control and Human-Machine Interface Technologies (NPIC&HMIT2009)
Country/Territory	United States
City	Knoxville, Tennessee
Period	2009-04-05 → 2009-04-09

Cite this

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title = "The choice of Pu242 fission chambers to monitor the fast neutrons in a high flux",

abstract = "Fission chambers are widely used for on-line measurements of neutron fluxes in irradiation reactors. When the flux is high with a significant thermal component, the measurement of the fast component is a concern and implies a careful choice of the deposit material. Indeed, most fissile materials have a cross section much higher with thermal neutrons than with fast ones. Moreover, a deposit chosen to favour fissions by fast neutrons will make radiative captures in the thermal domain, leading to a gradual modification of the isotopic compositions of the deposit that may dramatically increase the fissions with thermal neutrons. Within the framework ot the FNDS (Fast neutron Detector System) project, we performed simulations of the evolution of the isotopic composition and fission rate for several deposits under high fluxes. We show that Pu242 is the best choice to extract the fast component from a flux with a significant thermal component, provided that the impurities in Pu241 and Pu239 are small enough. However, an independent measurement of the thermal component appears to be necessary to compensate for the evolution of the Pu242 deposit.",

keywords = "Fission chambers, fast neutron flux, simulation",

author = "Philippe Filliatre and Ludovic Oriol and Christian Jammes and Ludo Vermeeren and Marcel W{\'e}ber",

note = "Score = 3; Sixth American Nuclear Society International Topical Meeting on Nuclear Plant Instrumentation, Control and Human-Machine Interface Technologies (NPIC&HMIT2009) ; Conference date: 05-04-2009 Through 09-04-2009",

year = "2009",

month = apr,

language = "English",

booktitle = "Proc. NPIC&HMIT 2009",

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Filliatre, P, Oriol, L, Jammes, C, Vermeeren, L & Wéber, M 2009, The choice of Pu242 fission chambers to monitor the fast neutrons in a high flux. in Proc. NPIC&HMIT 2009. La Grange Park, Illinois, United States, Sixth American Nuclear Society International Topical Meeting on Nuclear Plant Instrumentation, Control and Human-Machine Interface Technologies (NPIC&HMIT2009), Knoxville, Tennessee, United States, 2009-04-05.

TY - GEN

T1 - The choice of Pu242 fission chambers to monitor the fast neutrons in a high flux

AU - Filliatre, Philippe

AU - Oriol, Ludovic

AU - Jammes, Christian

AU - Vermeeren, Ludo

A2 - Wéber, Marcel

N1 - Score = 3

PY - 2009/4

Y1 - 2009/4

N2 - Fission chambers are widely used for on-line measurements of neutron fluxes in irradiation reactors. When the flux is high with a significant thermal component, the measurement of the fast component is a concern and implies a careful choice of the deposit material. Indeed, most fissile materials have a cross section much higher with thermal neutrons than with fast ones. Moreover, a deposit chosen to favour fissions by fast neutrons will make radiative captures in the thermal domain, leading to a gradual modification of the isotopic compositions of the deposit that may dramatically increase the fissions with thermal neutrons. Within the framework ot the FNDS (Fast neutron Detector System) project, we performed simulations of the evolution of the isotopic composition and fission rate for several deposits under high fluxes. We show that Pu242 is the best choice to extract the fast component from a flux with a significant thermal component, provided that the impurities in Pu241 and Pu239 are small enough. However, an independent measurement of the thermal component appears to be necessary to compensate for the evolution of the Pu242 deposit.

AB - Fission chambers are widely used for on-line measurements of neutron fluxes in irradiation reactors. When the flux is high with a significant thermal component, the measurement of the fast component is a concern and implies a careful choice of the deposit material. Indeed, most fissile materials have a cross section much higher with thermal neutrons than with fast ones. Moreover, a deposit chosen to favour fissions by fast neutrons will make radiative captures in the thermal domain, leading to a gradual modification of the isotopic compositions of the deposit that may dramatically increase the fissions with thermal neutrons. Within the framework ot the FNDS (Fast neutron Detector System) project, we performed simulations of the evolution of the isotopic composition and fission rate for several deposits under high fluxes. We show that Pu242 is the best choice to extract the fast component from a flux with a significant thermal component, provided that the impurities in Pu241 and Pu239 are small enough. However, an independent measurement of the thermal component appears to be necessary to compensate for the evolution of the Pu242 deposit.

KW - Fission chambers

KW - fast neutron flux

KW - simulation

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UR - http://knowledgecentre.sckcen.be/so2/bibref/6393

M3 - In-proceedings paper

BT - Proc. NPIC&HMIT 2009

CY - La Grange Park, Illinois, United States

T2 - Sixth American Nuclear Society International Topical Meeting on Nuclear Plant Instrumentation, Control and Human-Machine Interface Technologies (NPIC&HMIT2009)

Y2 - 5 April 2009 through 9 April 2009

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