Analysis of ¹⁶N Source Term in Primary Coolant System of FHR

Neutron spectrum of fluoride salt cooled high temperature reactor (FHR) was calculated by 3D Monte Carlo transport program KENO-Ⅵ in SCALE6.1 software package. The flow model of the ¹⁶N source term in the primary coolant system was established using Mathematica code. The ¹⁶N source term in the primary coolant was quantitatively analyzed and the distribution of ¹⁶N source term in different regions of the primary coolant at different flow velocities was analyzed. The results show that ¹⁶N source term concentration is obviously affected when the flow rate is greater than 4.15×10² cm³•s^-1 and less than 4.15×10⁶ cm³•s^-1. In the case of design velocity of FHR, the ¹⁶N source term in core accounts for 76.98% of the total ¹⁶N source term, the ¹⁶N source term in upper chamber accounts for 18.89%, and the rest accounts for 4.13%. The analysis method and conclusion can provide some references for the engineering design of FHR, the design of radiation protection and the accurate analysis of source terms.