[2L18-21] Criticality Analysis 2

[2L18] Modification of STACY for the study of criticality characteristics of fuel debris

(14)Reconsidering core configurations for the first criticality

*Satoshi GUNJI¹, Shouhei ARAKI¹, Tomoki YOSHIKAWA¹, Kazuhiko IZAWA¹, Kenya SUYAMA¹ (1. JAEA)

Keywords:New STACY, Critical Assembly, Nuclear Criticality Safety, Critical Experiment, Regulatory Review

The first criticality of the statistical criticality assembly called “STACY”, which JAEA has been modifying, is scheduled for 2024. At the spring 2023 annual meeting, we presented the results of a study on the basic core configuration for the first criticality, which is intended to reduce experimental uncertainties. However, in subsequent regulatory reviews, the Nuclear Regulation Authority instructed to create core configurations with the strictest safety factors (Reactor shutdown margin, etc.) among the permission, therefore the first critical core configurations were changed to cylindrical core configurations with grid intervals of 1.50 and 2.54 cm. This study presents the results of estimations such as critical water levels using multiple nuclear data and calculation codes.