Document: NUREG-0800
Document ID: 846ded8e-04ea-4031-8f64-62690ca967b6
Document Type: srp
Title: ANTICIPATED TRANSIENTS WITHOUT SCRAM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070570008.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.8
CFR Part: 
CFR Title: 

Content:
cases, the staff may accept the use of the ATWS licensing code, even though it cannot model all the required actions specified in EOPs. In these cases, supplemental sensitivity analysis can be used to demonstrate that: (1) the licensing code results are conservative; and (2) the plant’s ATWS response following the EOP actions comply with the NRC-approved BWR ATWS acceptance criteria. As an interim, the use of sensitivity analysis based on a non-licensing code or a code under staff review is acceptable, provided the code is capable of modeling, with reasonable degree of accuracy, the operator actions and the systems response as delineated by the EOPs. The licensee must demonstrate to the staff that the non-licensing code contains all features necessary for modeling the ATWS EOP actions and system actuations so that there is reasonable assurance that the ATWS acceptance criteria response results are adequate. The staff acceptance of the use of a non-licensing code is an interim measure. The licensees and the fuel vendors must commit to and submit the non-licensing code for staff review and approval. C. If the ATWS acceptance criteria cannot be met based on plant-specific EOP actions under the EPU and expanded operating domain, the licensee must modify the ATWS protection features to ensure that the criteria are satisfied. For example, the licensee may reduce the hot shutdown boron weight injection time or modify the EOP mitigation actions (e.g., water-level strategies). 6. For BWRs, the ATWS/Stability evaluation was generically dispositioned based on the Mitigation Actions for plants operating up to OLTP. A. For all applications, the reviewer will evaluate the implementation of the ATWS/Stability Mitigation Actions in design-specific EPGs, or plant-specific EOPs or EOIs. The reviewer will ensure that sufficient information has been provided to justify that the mitigation actions are effective in maintaining core coolability criteria for the limiting ATWS/Stability