Verification and validation of the MCNPX-PoliMi code for simulations of neutron multiplicity counting systems

详细信息    查看全文

• 作者：S.D. Clarke^a ; ^{clarkesd@umich.edu} ; E.C. Miller^a ; ^{ericcm@umich.edu} ; M. Flaska^a ; ^{mflaska@umich.edu} ; S.A. Pozzi^a ; ^{pozzisa@umich.edu} ; R.B. Oberer^b ; ^{obererrb@y12.doe.gov} ; L.G. Chiang^b ; ^{chianglg@y12.doe.gov}
• 关键词：3He multiplicity ; Active well coincidence counter ; MCNPX-PoliMi
• 刊名：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
• 出版年：2013
• 出版时间：1 February, 2013
• 年：2013
• 卷：700
• 期：Complete
• 页码：135-139
• 全文大小：428 K

文摘

Neutron coincidence counting is widely used in nuclear safeguards. Simulations of these systems can be performed using Monte Carlo codes such as MCNPX to aid in calibration or measurement design. However, the MCNPX coincidence-counting routines treat particle histories individually, therefore the dead time of the acquisition electronics is not treated. The MCNPX-PoliMi code provides the ability to model detailed effects such as data-acquisition electronics and system dead times. A specialized post-processing code has been developed to interpret the collision-log file and determine the response of a ³He multiplicity counter. The MCNPX-PoliMi simulation provides the full neutron multiplicity distribution measured by the ³He tubes. This distribution is used to compute the singles, doubles, and triples rates which are the quantities used to determine ²³⁵U mass. MCNPX-PoliMi has previously been validated with passive multiplicity measurements. In this study, a detailed analysis of the measurement system operating in active mode is presented for uranium-oxide standards ranging from 0.5 to 4.0 kg with a Canberra JCC-51 active well coincidence counter. MCNPX-PoliMi calculations are also compared with MCNPX. The two codes agree to within 1 % for the cases with negligible dead times. The simulations are validated with measurements performed at the Y-12 National Security Complex.