Protection systems design criteria

Chapter 4 presents the fundamentals of passivity the film and adsorption theories of passivity criterion for passivation methods for spontaneous passivation factors affecting passivation, such as the effect of solution velocity and acid concentration alloy evaluation anodic protection systems and design requirements. A fuU discussion on stainless steel composition and crystalline structure, oxidizer concentration, and alloy evaluation is included. The chapter also considers anodic protection to establish a basis for anodic... 

Criterion 10 - Reactor design. The reactor core and associated coolant, control, and protection systems shall be designed with appropriate margin to assure that specified acceptable fuel design limits are not exceeded during any condition of normal operation, including the effects of anticipated operational occurrences. 

Criterion 20 - Protection system functions. The protection system shall be designed (1) to initiate automatically the operation of appropriate systems including the reactivity control systems, to assure that specified acceptable fuel design limits are not exceeded as a result of anticipated operational occurrences and (2) to sense accident conditions and to initiate the operation of systems and components important to safety. 

Criterion 22 - Protection system independence. The protection system shall be designed to assure that the effects of natural phenomena, and of normal operating, maintenance, testing, and postulated accident conditions on redundant channels do not result in loss of the protection function, or shall be demonstrated to be acceptable on some other... 

The acceptance criterion for the resolution of USI A-26 is that adequate measures for protection of the reactor vessel from pressure transients shall be included in the system design. 

Criterion 21. Physical separation and independence of safety systems Separation and independence should apply in providing DiD for the design of a physical protection system. Criterion 23. Reliability of items important to safety Include the design of a physical protection system. 

Criterion 25. Single failure criterion Design of a physical protection system should prevent a single failure that will render the security function ineffective or unavailable. 

Criterion 42. Safety analysis of the plant design Anticipated operational occurrences (AOOs) and DBAs are evaluated in the safety analysis and include design of a physical protection system to protect against malevolent acts. 

Some Member States use explicit reliability requirements. In other Member States, reliability is only one aspect of demonstration of the performance required of safety systems and equipment. Various national practices have set goals for the performance of the protection system over and above the single failure criterion. This additional reliability is sometimes achieved by using double failure protection in parts of the protection system and/or by using equipment with a wider design margin. 

However, it would be most unusual for a cathodic protection system, typically designed to operate at 2 mA/ffi of steel surface, to operate in excess of 25 mA/ffi for sufficient time (several years) to cause deterioration in bond strength, unless the potential criterion was applied inappropriately. 

Criterion 3 - Fire protection. Structures, systems, and components important to safety shall be designed and located to minimize, consistent with other safety requirements, the probability and effect of fires and explosions. Noncombustible and heat resistant materials shall be used wherever practical throughout the unit, particularly in locations such as the containment and control room. Fire detection and fighting systems of appropriate capacity and capability shall be provided and designed to minimize the adverse effects of fires on structures, systems, and components important to safety. Firefighting systems shall be designed to assure that their rupture or inadvertent operation does not significantly impair the safety capability of these structures, systems, and components. 

Criterion 11 - Reactor inherent protection. The reactor core and associated coolant systems shall be designed so that in the power operating range the net effect of the prompt inherent nuclear feedback characteristics tends to compensate for a rapid increase in reactivity. 

Criterion 29 - Protection against anticipated operational occurrences. The protection and reactivity control systems shall be designed to assure an extremely high probability of accomplishing their safety functions in the event of anticipated operational occurrences. 

The acceptance criterion for the resolution of USI A-35 is that the design and capability for test and calibration of the under voltage protection schemes for the Class IE buses of the onsite power system (while connected to the offsite power source) shall conform to the guidance of BTP PSB-1 in Appendix A of SRP Section 8.3.1. 

The ESF actuation system is composed of redundant trains A, B, C, and D. The instrumentation and controls of each train are physically and electrically separate and independent. The ESF actuation system can sustain the loss of an entire train and still provide its required protective action. Specific ESF design criteria are addressed for environmental and seismic equipment qualification, single failure criterion, and minimum equipment and system response times. 

Criterion 81. Design for radiation protection The plant layout should be designed to minimize exposures and contamination of operating personnel by controlling access to areas with radiation hazards and areas of possible contamination. Ventilation systems shall be designed to minimize personnel exposures and control the spread of contamination. 

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