Monte Carlo shielding evaluation of a CSNS Multi-Physics instrument

• Main Authors: Tairan Liang, Fei Shen, Wen Yin, Juping Xu, Quanzhi Yu, Tianjiao Liang
• Format: Article
• Language: English
• Published: Elsevier 2019-12-01
• Series: Nuclear Engineering and Technology
• Online Access: http://www.sciencedirect.com/science/article/pii/S1738573318305606

The Multi-Physics (MP) instrument is one of 20 neutron spectrometers planned in the China Spallation Neutron Source (CSNS). This paper presents a shielding calculation for the MP instrument using Monte Carlo codes MCNPX and FLUKA. First, the neutrons that escape from the CSNS decoupled water moderator and are delivered to the beam line of the MP instrument are calculated to use as the source term of the shielding calculation. Then, to validate the calculation method based on multiple variance reduction techniques, a cross check between MCNPX and FLUKA codes is performed by comparing the calculation results of the dose rate distribution on a simplified beam line model. Finally, a complete geometry model of the MP instrument is set up, and the primary parameters for the shielding design are obtained according to the calculated dose rate map considering different worst-case scenarios. Keywords: Neutron beam line, Monte Carlo method, Shielding calculation