NFPA 805-2001 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants.
2.1 Intent. This chapter describes the general approach for establishing the fire protection requirements for a nuclear power plant. The chapter shall provide the requirements for the engineering analyses used to establish the required fire protection systems and features, including in particular the analyses used to support the performance-based fire protec- tion design that fulfills the goals, objectives, and criteria pro- vided in Chapter 1. 2.2 General Approach. The general approach of this stan- dard shall involve the following steps in accordance with Fig- ure 2.2: (a) Establish the fundamental fire protection program (see Chapter 3). (b) Identify fire areas and associated fire hazards. (c) Identify the performance criteria that apply to each fire area (see Section 1.5). (d) Identify systems, structures, and components (SSCs) in each fire area to which the performance criteria apply. (e) Select the deterministic and/or performance-based approach for the performance criteria (see Chapter 4). (f) When applying a deterministic approach, demon- strate compliance with the deterministic requirements (see Chapter 4). (g) When applying a performance-based approach, per- form engineering analyses to demonstrate that performance- based requirements are satisfied. These analyses shall include, for example, engineering evaluations, probabilistic safety assessments, or fire modeling calculations (see Section 2.4). (h)*Perform the plant change evaluation that demonstrates that changes in risk, defense-in-depth, and safety margins are acceptable (see 2.4.4). If any one of these is unacceptable, addi- tional fire protection features or other alternatives shall be implemented. (i) Develop a monitoring program to monitor plant per- formance as it applies to fire risk. Other Required Circuits. Other circuits that share common power supply and/or common enclosure with cir- cuits required to achieve nuclear safety performance criteria shall be evaluated for their impact on the ability to achieve nuclear safety performance criteria. (a) Common Power Supply Circuits. Those circuits whose fire- induced failure could cause the loss of a power supply required to achieve the nuclear safety performance criteria shall be identified. This situation could occur if the upstream protection device (i.e., breaker or fuse) is not properly coordi- nated with the downstream protection device. (See Appendix B for considerations when analyzing common power supply concerns.) (b) Common Enclosure Circuits. Those circuits that share enclosures with circuits required to achieve the nuclear safety performance criteria and whose fire-induced failure could cause the loss of the required components shall be identified. The concern is that the effects of a fire can extend outside of the immediate fire area due to fire-induced electrical faults on inadequately protected cables or via inadequately sealed fire area boundaries. (See Appendix B for considerations when analyz- ing common enclosure concerns.)NFPA 805 pdf download.