Nuclear Forensic Analysis on Nuclear Reactor Characteristics

Based on the pin-cell model and 3-D burnup calculation code MCCOOR,the nuclides compositions of fuel and moderator are simulated for the 5 MW graphite moderated and gas-cooling reactor. The characteristics of this reactor are analyzed with correlated nuclides analysis.Results are as the followings: the composition of ¹⁴C and ¹⁰Be in moderator could be the signature of total flux,the mainly fission products of radioactive nuclides,¹⁴⁴Ce,¹³⁴Cs,¹⁴⁷pm,¹⁵⁴Eu,⁹⁰Sr and ¹³⁷Cs,could be the signature ofreprocessing time and times of reprocessing,and the correlated nuclide number ratio of ²³⁸u vs.totalPu could be the signature of reactor type.Thus,for nuclear forensic analysis on the dismantlement of production reactor,the sampling data of the nuclides ¹⁴C and ¹⁰Be in moderator could be used to identify the operation history of the reactor, and the sampling data of the main fission product of radioactive nuclides in the reprocessing pool could be used to identify the times of reprocessing.For nuclear forensic analysis on nonproliferation cases,the reactor type of intercepted material could be identified by analyzing the correlated nuclides ratios,²³⁸pu v.s.total Pu and ²⁴²Pu v.s.²⁴⁰Pu,which is essential to narrow down the possible origination range of the intercepted material.