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Conference Article: Mcnp Simulations And Measurements For The Validation Of The PBMR Burnup Measurement System At Necsa

Abstract

PBMR (PBMR Pty (Ltd)) is undertaking a verification and validation (V&V) exercise to verify and validate the principle for burnup measurement that will be used in the PBMR plant. This exercise was initiated at a spectroscopic facility at SAFARI-1, the research reactor of the South African Nuclear Energy Corporation (Necsa) and used SAFARI-1 fuel elements for measurements. The prototype Burnup Measurement System (BUMS) is used in the V&V exercise. The initial activity in the V&V process was to determine whether the spectroscopic facility at Necsa meets the desired criteria for the exercise and to test the performance of the BUMS. One of the specifications for the BUMS is a total effective detector count rate of 10+5 counts per second (cps), to simulate the actual count rate under which the detector system will be operated. This raised questions on the applicability of the existing collimators at the facility and if they had to be changed, what the new dimensions should be. The collimator facility was subsequently modelled in MCNP and measurements were performed to validate the MCNP model as well as the assumptions made for the calculations. The initial comparison between experiment and calculation proved very promising, which provides validation of the MNCP model used for the calculations. This paper presents the modelling approach that was taken in MCNP and discusses the consequences of the comparison of the experimental and calculational results.

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Reference:

Proceedings of the Conference on High Temperature Reactors, Beijing, China, September, 22-24, 2004

International Atomic Energy Agency, Vienna (Austria)

HTR-2004, pp:1-13