Dazhi Qian

A Monte Carlo code to get response spectrum of ions for Neutron Depth Profiling

This paper presents a Monte Carlo code to get response spectrum of ions for the Neutron Depth Profiling (NDP) technique called Monte Carlo NDP (MC-NDP) that simulates the behavior of ions transmitted through a sample matrix and generates the energy spectrum for a specified detector. The MC-NDP model is based on the Ziegler–Biersack–Littmark Model, but incorporates the advantages of TRIM and CORTEO. The Impulse Approximation method is used to determine the flight length with the indexical interpolation method rather than the Magic algorithm for the scattering angle between ions and nucleus. This makes MC-NDP more efficient and convenient to simulate entire ion histories by a Monte Carlo approach. MC-NDP’s results agree well with both TRIM results and the experimental data.

Transient Thermal-Hydraulic Analysis of Single Flow Channel Blockage in the JRR-3M 20-MW Research Reactor

Abstract A flow blockage analysis model of a single channel is established using the best-estimate code RELAP5/MOD3.4. The reactor core is divided into seven hot channels, one average channel, one bypass channel, and corresponding fuel plates to take into account the interaction between the obstructed channel and adjacent channels. The coolant system is also modeled in detail to perform a better estimation. As a typical pool-type research reactor, JRR-3M is chosen for the analysis. The results indicate that the model can effectively simulate a single-channel blockage accident using the RELAP5/MOD3.4 code. Also, the thermal-hydraulic parameters in the blocked channel would be significantly affected if bubbles are generated as the blockage ratio continues to increase, which may damage the integrity of the fuel plate. Meanwhile, as for flow blockage of a single channel, the effect on adjacent channels is limited, even under high-blockage-ratio conditions.

One candidate method based on short-lived indicator for burnup analysis

One novel gamma spectrometry method based on short-lived fission products was developed that can infer the level of burnup without complex computations or knowing irradiation history. The relationship between the burnup information and equilibrium concentration of short-lived indicators was derived. In addition, new candidate indicators for gamma spectrum analysis, such as 88Kr, 91Sr, 92Sr, 135I and 142La were screened out. The results of three cases simulated with ORIGEN and MCNP were in good agreement with the theoretical values.