Application of the First Collision Source Method to CSNS Target Station Shielding Calculation

TL;DR

This paper presents the application of the RAY3D module, utilizing a first collision source method, to improve shielding calculations at CSNS, effectively reducing ray effects and validating results against benchmarks and Monte Carlo solutions.

Contribution

The paper introduces the application of RAY3D with a first collision source method to neutron shielding calculations at CSNS, demonstrating its effectiveness in mitigating ray effects.

Findings

RAY3D effectively mitigates ray effects in shielding calculations.

Numerical results agree well with Monte Carlo solutions.

Dose rate at CSNS beamline end is below safety threshold.

Abstract

Ray effects are the inherent problem of discrete ordinates method. RAY3D, a functional module of ARES which is a discrete ordinates code system, employs a semi-analytic first collision source method to mitigate ray effects. This method decomposes the flux into uncollided and collided components, and then calculates them with analytical method and discrete ordinates method respectively. In this article, RAY3D is validated by the Kobayashi benchmarks and applied to the neutron beamline shielding problem of China Spallation Neutron Source (CSNS) target station. Numerical results of the Kobayashi benchmarks indicate that DONTRAN3D with RAY3D solutions agree well with the Monte Carlo solutions. The dose rate at the end of the neutron beamline is less than 10.83 {\mu}Sv/h in CSNS target station neutron beamline shutter model. RAY3D can effectively mitigate ray effects and obtain relatively reasonable results.