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:
C evaluations of vendor models and analyses addressing ATWS events, the agency formally identified the ATWS as Unresolved Safety Issue (USI) A-9, “Anticipated Transients Without Scram.” The agency presents the NRC staff’s studies and findings regarding USI A-9 in NUREG-0460. In 1986, the NRC resolved USI A-9 through publication of 10 CFR 50.62, the ATWS rule (the rule). Although the rule does not require ATWS analyses, SECY 83-293 and the Federal Register notice of the final rule in 49 FR 26036 present the bases for current regulatory requirements related to ATWS events, including the associated regulatory evaluation. The rule requires that certain light-water-cooled plants have prescribed systems and equipment that have been determined to reduce the risks attributable to ATWS events, for each of the nuclear steam supply system (NSSS) vendor’s designs, to an acceptably low level. The rule also requires applicants to demonstrate the adequacy of their plants’ prescribed systems and equipment. During design certification (DC) reviews of evolutionary plant designs, the NRC developed additional requirements criteria (i.e., to provide a diverse scram system or to demonstrate that the consequences of ATWS events are acceptable). COL Action Items and Certification Requirements and Restrictions. For a DC application, the review will also address COL action items and requirements and restrictions (e.g., interface requirements and site parameters). For a COL application referencing a DC, a COL applicant must address COL action items (referred to as COL license information in certain DCs) included in the referenced DC. Additionally, a COL applicant must address requirements and restrictions (e.g., interface requirements and site parameters) included in the referenced DC. Review Interfaces Other SRP sections interface with this section as follows: 1. General information on transient and accident analyses is provided in SRP Section 15.0. 2. Design basis radiological