Appendix R to Part 50, Fire Protection Program for Nuclear Power Facilities Operating Prior to January 1, 1979 (Appendix R) was written as an addition to Code of Federal Regulations (CFR) 50.48 and details the requirements to be able to perform safe shutdown in the event of a fire and to mitigate the release of radiation to the public.  ARS works closely with power plants to find cost-effective solutions to meeting those regulations.

ARS engineers and consultants are well-versed in the codes and regulations set forth in Appendix R and can help plants modify outdated designs and procedures in order to be in compliance with Nuclear Regulatory Guidelines.

In accordance with the Appendix R to Part 50, ARS identifies and evaluates the following:

• Fire Protection Programs, including defense in depth fire protection to prevent fires from starting; rapidly detect, control, and promptly extinguish fires that occur; and provide protection for structures, systems, and components important to safety.
• Fire Hazards Analysis
• Fire Prevention Features
• Safe Shutdown Capability
• Alternative and Dedicated Shutdown Capability
• Fire Brigade Training and Practice
• Emergency Lighting and Administrative Controls
• Fire Strategies
• Fire Barrier Cable Penetration Seal Qualification and Fire Doors
• Oil Collection System for Reactor Coolant Pump

In addition, ARS consultants recommend other modifications or general design requirements to meet the prescriptive requirements of Appendix R.

Safe Shutdown Analysis

The Nuclear Energy Institute published Revision 2 of NEI 00-01, Guidance for Post-Fire Safe Shutdown Circuit Analysis, in 2009. NEI 00-01 provides the deterministic methodology for post-fire shutdown analysis in accordance with Appendix R guidelines and risk-informed methods for resolving multiple spurious operations circuit failures.  In a Safe Shutdown Analysis, ARS performs a review of the ways in which a plant’s operating systems could be affected by a fire and create a plan to address any identified challenges to a safe shutdown.

ARS uses the methodologies set forth in NEI 00-01 to perform post-fire safe shutdown analysis, including the following:

• Safe Shutdown Systems and Path Development
• Safe Shutdown Equipment Selection
• Cable Selection
• Cable Location
• Fire Area Assessment and Compliance Strategies
• Circuit Analysis
• Multiple Spurious Operations (MSO) Panels

Safe Shutdown Analysis identifies the systems, structures, and components important to safety and identifies conditions that could challenge the ability to maintain at least one redundant train of systems, structures, and components important to safety free of fire damage.  By identifying these conditions and recommending mitigation strategies, ARS assists clients demonstrate safety and reduce risk through modifications or procedural changes.  In some cases, detailed analysis can result in a reduced number of modifications, such as fire wrap, that would otherwise be necessary to protect required systems.

As part of Japan’s post-Fukushima restart efforts, ARS has supported clients by performing safe shutdown analyses to assist our clients demonstrate the ability to maintain the ability to safely shutdown the plant in the event of a fire.  By demonstrating deterministic safety in accordance with NEI 00-01 to the regulator, several plants have been acquired restart permission.  While operating, plants can use this deterministic baseline as a reference and input for future probabilistic risk assessments to further reduce risk and maintain safe and stable conditions.  In addition to safe shutdown analysis, ARS has supported these restart efforts by performing FPRA tasks and Reactor Oversight Program assessments.

While written for the nuclear power industry, the methodologies for safe shutdown analysis set forth in NEI 00-01 and concepts set forth in Appendix R can be applied to wide-ranging industries to ensure that one train of systems, structures, and components remains free from the affects of a single fire.  ARS’ experience in ensuring train separation and safe shutdown capabilities assists our clients in demonstrating safety, the ability to maintain stable conditions, and continuity of operations.