OVERVIEW OF ZION COMPARATIVE ANALYSIS PROJECT FOR ASSESSMENT OF BORAL~? NEUTRON ABSORBER MATERIAL PERFORMANCE AND MONITORING IN SPENT FUEL POOLS

摘要

Neutron absorber materials are used in spent fuel pool (SFP) storage racks to control reactivity. In the United States, about half of the operating plants currently use BORAL? neutron absorber material in SFP racks. Although operational experience spanning more than 25 years has not shown any loss of the BORAL? core material, corrosion effects, including blisters and pits, have been observed and reported. To improve understanding for the behavior of BORAL? in SFPs and evaluate the performance of monitoring approaches, EPRI initiated the Zion comparative analysis project in 2014. The Zion project involves three phases. During the first phase of the project, in situ measurements were performed on selected SFP rack panels in December 2014. Panels for in situ measurements were selected after an extensive analysis of each panel in the pool to ensure that the selected panels represented the pool in terms of variation in neutron and gamma dose values. As part of the second phase of the project, the remaining 10 coupons from the Zion SFP were shipped to a Penn State University (PSU) laboratory for analysis in January 2015. During the final phase of the project, a subset of the panels for which in situ measurements were performed will be harvested from the Zion SFP, cut into samples, and analyzed at PSU. The overall scope of this project will allow comparison of in situ measurements to real panel data as well as data obtained from coupon analysis. In this paper, an overview of the Zion comparative analysis project, the criteria and procedure for panel selection for in situ measurements and harvesting, preliminary coupon analysis results and in situ measurement results are presented.