Analysis of the Effect of the Primary Shield Structures on Dose Rates in the Operating Floor

Abstract

Improving the shielding configuration and reducing the dose rates in the operating floor are realistic and significant for controlling the material activation and effective exposure dose of workers. The reactor cavity configuration is very complex and the structure of the primary shield wall is one of the most important issues related to the radiation streaming up to the operating floor. The aim of the present paper is to perform an analysis of the effect of the primary shield structure on dose rates in the operating floor and give some advices about design provisions in NNPs radiation shielding. A typical reactor core was modeled and the results of sensitivity analyses on some parameters (such as the gap size between the reactor vessel outer surface and the primary shield wall, the limonite size and thickness, the configuration of the support bracket, etc.) that might affect the dose rates in the operating floor are documented. The discrete ordinates (S_N) DORT method was used and preliminary numerical results demonstrate that the configuration of the concrete especially the inner radius of the upper shielding concrete should be carefully chosen in shielding design. Besides, the mutual complementation of the limonite and the support bracket should be considered to reach an optimal shielding purpose.