ROP Cornerstone & Performance Indicators

Reactor Safety

Mitigating Systems - The objective of this cornerstone is to monitor the availability, reliability, and capability of systems that mitigate the effects of initiating events to prevent core damage. Licensees reduce the likelihood of reactor accidents by maintaining the availability and reliability of mitigating systems. Mitigating systems include those systems associated with safety injection, decay heat removal, and their support systems, such as emergency AC power. This cornerstone includes mitigating systems that respond to both operating and shutdown events. There are five indicators in this cornerstone:

• Emergency AC Power System Safety System Unavailability - The average of the individual train unavailabilities. Train unavailability is the ratio of the hours the train is unavailable to the number of hours the train is required to be able to perform its intended safety function.
• High Pressure Injection System Safety System Unavailability - The average of the individual train unavailabilities. Train unavailability is the ratio of the hours the train is unavailable to the number of hours the train is required to be able to perform its intended safety function.
• BWR Heat Removal System/PWR Auxiliary Feedwater System Safety System Unavailability -The average of the individual train unavailabilities. Train unavailability is the ratio of the hours the train is unavailable to the number of hours the train is required to be able to perform its intended safety function.
• Residual Heat Removal System Safety System Unavailability - The average of the individual train unavailabilities. Train unavailability is the ratio of the hours the train is unavailable to the number of hours the train is required to be able to perform its intended safety function.
• Safety System Functional Failures - The number of events or conditions that alone prevented, or could have prevented, the fulfillment of the safety function of structures or systems in the previous four quarters.

 

Mitigating System Indicator			Thresholds
			(White) Increased Regulatory Response Band	(Yellow) Required Regulatory Response Band	(Red) Unacceptable Performance Band
Emergency Power	< 2 EDG		> 2.5 %	> 5.0 %	> 10.0 %
	> 2 EDG		> 2.5 %	> 10.0 %	> 20.0 %
	Hydro Emerg. Power		TBD	TBD	TBD
Boiling-Water Reactor (BWR)	High Pressure Injection System	HPCI	> 4.0 %	> 12.0 %	> 50.0 %
		HPCS	> 1.5 %	> 4.0 %	> 20.0 %
	Heat Removal System	RCIC	> 4.0 %	> 12.0 %	> 50.0 %
Pressurized-Water Reactor (PWR)	High Pressure Injection System	HPSI	> 1.5 %	> 5.0 %	> 10.0 %
	Heat Removal System	AFW	> 2.0 %	> 6.0 %	> 12.0%
Residual Heat Removal System		RHR	> 1.5 %	> 5.0 %	> 10.0 %
Safety System Functional Failures		BWR	> 6.0	N/A	N/A
		PWR	>5.0	N/A	N/A

Thursday, April 14, 2011