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It evaluates the safety performance off NPPs using 2 areas, 4 categories and 15 indicators and provides the evaluation result in 4 colors for public understanding

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Reactor Safety

Reactor Safety Area

This area monitors the operational events of the nuclear power plant and the reliability of each multiple barrier and safety system to prevent accident or mitigate its consequence.
01. Operational Safety Category
The objective of this category is to monitor the stability of NPP operation and to limit the frequency of those events that affect the plant's safe operation. This category focuses on operations and events at NPPs that could lead to an accident. These events could include transients leading to a plant shutdown, or unplanned power reductions by more than 30%.
Unplanned Reactor Scram(URS)

The URS indicator is the number of unplanned reactor scrams during possible critical hours per actual critical hours.

Definition : URS = No. of reactor scram × Possible critical hours / Actual critical hours

Note : All the automatic and manual scrams prescribed in the reporting criteria are included.

Boundary Value

Boundary Value table
providing that Grade, Color, Boundary Value
Grade Color Boundary Value
Excellent Excellent grade G   Evaluated Value < 3
Good Good grade C 6 ≤ Evaluated Value < 6
Normal Normal garde Y 6 ≤ Evaluated Value < 20
Warning Warning grade O 20 ≤ Evaluated Value  
Unplanned Power Reduction(UPR)

UPR indicator is the number of unplanned power reduction by more than 30% during possible critical hours per actual critical hours.

Definition : UPR = No. of power reduction more than 30% × Possible critical hours / Actual critical hours

Note : Power reductions requested by the load dispatcher, and unplanned power changes caused by the external event such as typhoon, or the transient of the off-site transmission line are not included.

Boundary Value

Boundary Value table
providing that Grade, Color, Boundary Value
Grade Color Boundary Value
Excellent Excellent grade G   Evaluated Value < 6
Good Good garde C 6 ≤ Evaluated Value < 12
Normal Normal grade Y 12 ≤ Evaluated Value < 20
Warning Warning garde O 20 ≤ Evaluated Value  
Unplanned Reactor Scram with Complications(USwC)

USwC indicator is the number of unplanned reactor scrams with complications during possible critical hours.

Definition : USwC = No. of unplanned reactor scram with complications

Note: This indicator is a subset of the URS indicator and the scram considered in this indicator must have counted in the URS indicator.

Boundary Value

Boundary Value table
providing that Grade, Color, Boundary Value
Grade Color Boundary Value
Excellent Excellent garde G   Evaluated Value ≤ 1
Good Good garde C 1 < Evaluated Value  
Normal Normal grade Y   Evaluated Value  
Warning Warning garde O   Evaluated Value  

 

02. Safety System Category
The purpose of this category is to monitor the readiness of important safety systems which are designed to prevent an accident or reduce the consequences of the accident. The safety injection system, the emergency diesel generator system, the auxiliary feed water system, the residual heat removal system, and the cooling water system are selected as the key safety systems to perform their safety functions in response to off-normal events or accidents. As the readiness of these systems is checked by periodic testing and actual performance, the unavailability of each system is selected as the specific performance indicator for this category. The number of safety system functional failures is also considered.
Safety Injection System Unavailability(SI)

SI indicator is the fraction of unavailable hours against the hours that SI system is required.

Definition : SI = (Planned + Unplanned)Unavailable hours + (Fault cwposure unavailable hours) / (Hours system required) x (Number of trains)

Boundary Value

Boundary Value table
providing that Grade, Color, Boundary Value
Grade Color Boundary Value
Excellent Excellent garde G   Boundary Value < 0.015
Good Good garde C 0.015 ≤ Boundary Value < 0.05
Normal Normal garde Y 0.05 ≤ Boundary Value < 0.1
Warning Warning grade O 0.1 ≤ Boundary Value  
Emergency Diesel Generator System Unavailability(EDG)

EDG indicator is the fraction of unavailable hours against the hours that EDG system is required.

Definition : EDG = (Planned + Unplanned)Unavailable hours + (Fault cwposure unavailable hours) / (Hours system required) x (Number of trains)

Boundary Value

Boundary Value table
providing that Grade, Color, Boundary Value
Grade Color Boundary Value
Excellent Excellent garde G   Evaluated Value < 0.025
Good Good garde C 0.025 ≤ Evaluated Value < 0.05
Normal Normal grade Y 0.05 ≤ Evaluated Value < 0.1
Warning Warning grade O 0.1 ≤ Evaluated Value  
Auxiliary Feedwater System Unavailability(AFW)

AFW indicator is the fraction of unavailable hours against the hours that AFW system is required.

Definition : AFW = (Planned + Unplanned)Unavailable hours + (Fault exposure unavailable hours) / (Hours system required) x (Number of trains)

Boundary Value

Boundary Value table
providing that Grade, Color, Boundary Value
Grade Color Boundary Value
Excellent Excellent grade G   Boundary Value < 0.015
Good Good grade C 0.015 ≤ Boundary Value < 0.05
Normal Normal grade Y 0.05 ≤ Boundary Value < 0.1
Warning Warning grade O 0.1 ≤ Boundary Value  
Residual Heat Removal System Unavailability(RHR)

RHR indicator is the fraction of unavailable hours against the hours that RHR system is required.

Definition : RHR= (Planned + Unplanned)Unavailable hours + (Fault exposure unavailable hours) / (Hours system required) x (Number of trains)

Boundary Value

Boundary Value
Grade, Color, Boundary Value
Grade Color Boundary Value
Excellent Excellent grade G   Boundary Value < 0.015
Good Good grade C 0.015 ≤ Boundary Value < 0.05
Normal Normal grade Y 0.05 ≤ Boundary Value < 0.1
Warning Warning grade O 0.1 ≤ Boundary Value  
Cooling Water System Unavailability(CW)

CW indicator is the fraction of unavailable hours against the hours that CW system is required.

Definition : RHR= (Planned + Unplanned)Unavailable hours + (Fault exposure unavailable hours) / (Hours system required) x (Number of trains)

Boundary Value

Boundary Value
Grade, Color, Boundary Value
Grade Color Boundary Value
Excellent Excellent grade G   Boundary Value < 0.015
Good Good grade C 0.015 ≤ Boundary Value < 0.05
Normal Normal grade Y 0.05 ≤ Boundary Value < 0.1
Warning Warning grade O 0.1 ≤ Boundary Value  
Safety System Functional Failures(SSFF)

SSFF indicator is the number of events or conditions that prevented, or could have prevented the fulfillment of the safety function.

Definition : SSFF= No. of safety system functional failures

Boundary Value

Boundary Value
Grade, Color, Boundary Value
Grade Color Boundary Value
Excellent Excellent grade G   Boundary Value ≤ 5
Good Good grade C 5 < Boundary Value  
Normal Normal grade Y   Boundary Value  
Warning Warning grade O   Boundary Value  
03. Multiple Barriers Category
The purpose of this category is to provide reasonable assurance that the barriers, based on the concept of "Defense in Depth", to protect the public from radionuclide releases during normal operation and under accident condition. These multiple barriers are including not only the physical design barriers, such as the fuel rods, the reactor pressure vessel and associated pipes, and the containment building, but also the non-physical barrier, emergency preparedness, as part of adequate measures to protect the public health and safety during a radiological emergency.
Fuel Reliability(FR)

FR indicator is the percentage of the maximum value of I-131 in the RCS to the limit value of Technical Specification.

Definition : FR = Specific activity of I-131 in the RCS / Limit value of Technical Specification x 100(%)

Note : Maximum value over a month during the evaluating period, for each quarter will be used for the calculation of indicator value

Boundary Value

Boundary Value
Grade, Color, Boundary Value
Grade Color Boundary Value
Excellent Excellent grade G   Evaluated Value < 50% of limit value
Good Good grade C 50% of limit value ≤ Evaluated Value < 70% of limit value
Normal Normal grade Y 70% of limit value ≤ Evaluated Value < 100% of limit value
Warning Warning grade O 100% of limit value ≤ Evaluated Value  
Reactor Coolant Leakage(RCL)

RCL indicator is the percentage of the maximum RCS leakage rate to the limit value of Technical Specification.

Definition : RCL = Maximum leakage rate of RCS / Limit value of Technical Specification x100(%)

Note : Maximum value used for the calculation includes both the identified and unidentified leakage.

Boundary Value

Boundary Value
Grade, Color, Boundary Value
Grade Color Boundary Value
Excellent Excellent grade G   Evaluated Value < 50% of limit value
Good Good grade C 50% of limit value ≤ Evaluated Value < 70% of limit value
Normal Normal grade Y 70% of limit value ≤ Evaluated Value < 100% of limit value
Warning Warning grade O 100% of limit value ≤ Evaluated Value  
Containment Reliability(CR)

CR indicator is the combination of ILRT results and LLRT results.

Definition : CR = Results of ILRT(70%) + Results of LLRT(30%)

Note : Criteria of ILRT(Integrated Leak Rate Test) results and LLRT(Local Leak Rate Test) results are based on the La of the plant Technical Specification.

Boundary Value

Boundary Value
Grade, Color, Boundary Value
Grade Color Boundary Value
Excellent Excellent grade G 90% ≤ Evaluated Value  
Good Good grade C 80% ≤ Evaluated Value < 90%
Normal Normal grade Y 60% ≤ Evaluated Value < 80%
Warning Warning grade O   Evaluated Value < 60%

 

Emergency Preparedness(EP)

EP indicator is the combination of Emergency exercise, Training of emergency personnel and emergency facility plus Response capability(only when the Radiation Alert is declared).

Definition : EP = Achievments in emergency exercise + Training of emergency personnel + Emergency facilities + Response capability for emergency (Only when the radiation alert is alerted)

Note : This indicator is evaluated based on the data over the previous three years. Response capability is evaluated with respect to the degree of the EOP observance.

Boundary Value

Boundary Value
Grade, Color, Boundary Value
Grade Color Boundary Value
Excellent Excellent grade G 90% ≤ Evaluated Value  
Good Good grade C 80% ≤ Evaluated Value < 90%
Normal Normal grade Y 60% ≤ Evaluated Value < 80%
Warning Warning grade O   Evaluated Value < 60%