Use of a training simulator in the regulatory evaluation of mitigative actions to resolve ATWS/stability issues

This paper summarizes the results of a training simulator study to evaluate emergency procedure guideline (EPG) revisions proposed by the Boiling Water Reactors Owners' Group (BWROG) to mitigate the consequences of unstable power oscillations during anticipated transients without scram (ATWS). The main purpose of these ATWS simulations was to evaluate the performance of the modified EPGs. The main conclusions derived from this evaluation are that the proposed EPG modifications are necessary to avoid the likelihood of instabilities during ATWS events, and that the modifications can be implemented and carried out by operators during ATWS events within the time constraints assumed in detailed analyses using the TRACG and EPA/HIPA codes. (author)