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:
ce the risk attributable to the ATWS events, to an acceptable level. In addition, the applicants must submit information sufficient to demonstrate the adequacy of the implemented ATWS features. Design and quality assurance criteria for the required systems and equipment should meet or exceed the criteria established in conjunction with ATWS rulemaking, as described in SRP Section 7.1, Appendix A, to ensure adequate independence, diversity, and reliability where required by the ATWS rule. 1. Acceptance criteria for Boiling Water Reactors (BWRs): A. Equipment shall be provided to initiate an automatic reactor coolant re-circulation pumps trip under conditions indicative of an ATWS. B. An alternate rod injection system (ARI) is provided independent and diverse from the reactor trip system sensor output to the final actuation device. The system shall have independent scram air header exhaust valve. C. A standby by liquid control system (SLCS) shall be provided that is capable of initiating reactivity control equivalent to injection of 326 liters per minute (or 86 gallons per minute) of 13 weight percent sodium pentaborate decahydrate solution of Boron-10 into a 638 centimeters (251 inches) inside diameter reactor pressure vessel operating at a power density consistent with the original licensed thermal power (OLTP). D. The SLCS initiation is automatic for the plants specified in 10 CFR 50.62(c)(4). E. For BWRs, reactor coolant system pressures should not exceed ASME Service Level C limits (approximately 10.3 MPa (1500 psi). F. Each plant Emergency Operating Procedures (EOPs) or Instructions (EOIs) must implement the ATWS/Stability Mitigation Actions as described in References 8 and 10. The two main mitigation actions are: i. Following a failure to scram, the reactor vessel water level must be lowered to a level below the feedwater spargers that will allow vessel steam to preheat the cold feedwater. ii. if unstable power oscillations are detected following a failure to