Safe Shutdown Assessments
10 CFR 50, Appendix A, General Design Criterion 3 provides the design bases requirements for protecting nuclear facilities from the effects of a fire. 10CFR50.48 how compliance with GDC 3 can be met in nuclear facilities. Depending on the licensing condition for each facility, either all of Appendix R, specific sections of Appendix R the rule apply for each facility, or none. Appendix R is applicable to nuclear power plants licensed prior to January 1, 1979. Other regulatory documents govern the Fire Protection requirements for plants licensed prior to January 1, 1979 (e.g., Branch Technical Position (CMEB) 9.5-1, NUREG 0800). However, if Appendix R is required by the plant's license condition, at least three sections of Appendix R have been deemed important enough to meet:
- Section III.G Safe Shutdown Capability
- Section III.J Emergency Lighting
- Section III.O Reactor Coolant Pump Lube Oil Collection Systems
In addition to the defense-in-depth approach to fire protection, nuclear facilities are required to demonstrate that the ability to achieve and maintain safe shutdown in the event of a fire in any area of a power plant. Safe Shutdown assessments require a number of detailed steps involving identification and analysis of requisite systems the plant needs to achieve and maintain safe shutdown. Once the requisite systems are identified, the related components and circuits (including associated circuits) are reviewed for compliance with the specific separation criteria of 10 CFR 50 Appendix R, Section III.G. For those areas not in compliance, studies are completed to determine whether:
- Modifications are required to bring the area into compliance, or
- An exemption is justified based on a rigorous fire hazards analysis for the specific fire areas in question.
Emergency lighting is required in areas where manual actions are performed or egress into or through an area is required by an operator. Section III.J requires emergency lighting with at least an 8-hour battery backup be provided to assist operators in performing these manual actions.
RCP lube oil systems are considered to be a significant fire hazard. Section III.O requires that a lube oil collection system be provided such that it is able to contain the entire lube oil inventory from potential leakage points in the system, and that the collection system be seismically qualified.
How Tri-En can help
Performing Appendix R Safe Shutdown assessments is one of Tri-En’s specialties. For this complex effort, we can provide a detailed, in-depth re-examination and re-analysis to identify the primary and auxiliary safe shutdown systems required to support safe shutdown in the event of a postulated exposure fire. The final product is a comprehensive Safe Shutdown analysis, performed in accordance with the requirements outlined in 10 CFR 50, Appendix R, and includes guidance and direction provided by the NRC.
Tri-En can perform the above assessment to reconfirm the adequacy of the existing design when compared against the specific criteria of Appendix R, Section III.G. For the remaining areas, modifications and/or exemption requests may be needed to either achieve specific conformance or achieve equivalent protection. Because of our knowledge and experience, we can offer solutions that will best address the utility’s both short term and long term goals.
Manual actions that are credited in the safe shutdown assessments will require 8-hour battery backed emergency lighting in accordance with the criteria of Appendix R, Section III.J. Tri-En can identify the locations where emergency lighting is required in order to successfully complete the manual action.
In addition, Tri-En can evaluate the existing RCP lube oil collection systems to determine if the design complies with the criteria provided in Appendix R, Section III.O.
Tri-en can also evaluate compliance with other sections of Appendix R, as applicable, in the facility's license condition requirements.