Control Rod Worth Evaluation for the Monju Restart Core

The present paper describes the evaluation of the control rod worth data obtained in the Monju restart core. The best-estimate value and its uncertainty are evaluated in detail. As in the criticality evaluation, data obtained in the previous test are evaluated in the same level of detail.

Evaluated results of control rod worth are consistent among control rods at symmetrical positions for a random uncertainty. The experimental uncertainty is ±2%, where the dominant uncertainty originates from the delayed neutron parameters used in the period method.

The correlation in the uncertainties is also evaluated among different control rods and tests. One can discuss a difference in worth among different control rods and cores without a detailed knowledge of the original uncertainty evaluation.

Based on the evaluated data, calculation accuracy is investigated with JENDL-3.3 and JENDL-4.0. It is confirmed that the calculation accuracy is within an experimental uncertainty of ±2% for each layer and ¹⁰B content.