Advances for the time-dependent Monte Carlo neutron transport analysis in McCARD

• Published in: Nuclear engineering and technology Vol. 55; no. 7; pp. 2712 - 2722
• Main Authors: Jang, Sang Hoon, Shim, Hyung Jin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2023; Elsevier; 한국원자력학회
• Subjects: C5G7-TD; History-based batch method; McCARD; Optimum detector position; Pulsed-neutron-source experiment; Time-dependent Monte Carlo; Transient analysis; 원자력공학; McCARD; Time-dependent Monte Carlo; Pulsed-neutron-source experiment; Optimum detector position; History-based batch method; Transient analysis; C5G7-TD
• ISSN: 1738-5733; 2234-358X
• DOI: 10.1016/j.net.2023.04.007

For an accurate and efficient time-dependent Monte Carlo (TDMC) neutron transport analysis, several advanced methods are newly developed and implemented in the Seoul National University Monte Carlo code, McCARD. For an efficient control of the neutron population, a dynamic weight window method is devised to adjust the weight bounds of the implicit capture in the time bin-by-bin TDMC simulations. A moving geometry module is developed to model a continuous insertion or withdrawal of a control rod. Especially, the history-based batch method for the TDMC calculations is developed to predict the unbiased variance of a bin-wise mean estimate. The developed methods are verified for three-dimensional problems in the C5G7-TD benchmark, showing good agreements with results from a deterministic neutron transport analysis code, nTRACER, within the statistical uncertainty bounds. In addition, the TDMC analysis capability implemented in McCARD is demonstrated to search the optimum detector positions for the pulsed-neutron-source experiments in the Kyoto University Critical Assembly and AGN-201K.