ML20236X524
| ML20236X524 | |
| Person / Time | |
|---|---|
| Issue date: | 07/27/1998 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML20236X251 | List: |
| References | |
| NUDOCS 9808100066 | |
| Download: ML20236X524 (11) | |
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e e SAFETY PERFORMANCE INDICATORS DRAFT 7/27/98 REACTOR COOLANT SYSTEM (RCS) ACTIVITY PURPOSE This indicator deals with the integrity of the fuel cladding barrier and monitors performance to ensure that, in the event of analyzed transients or accidents, the doses will be held to a small fraction of the 10 CFR 100 limits.
DEFINITION Reactor Coolant System specific activity is defined as the dose equivalent specific iodine cctivity as defined in plant technical specifications (TS).
REGULATORY THRESHOLD Dose equivalent I 131 > 0.50 Ci/gm [or 50% TS limit] (PWR)
> 0.1 Ci/gm [or 50% TS limit] (BWR)
SAFETY THRESHOLD 1
- Dose equivalent I-131 > 1.0 Ci/gm [or TS limit] (PWR)
> 0.2 Ci/gm [or TS limit] (BWR)
BASES FOR THRESHOLDS The Regulatory threshold is set at 50% of the technical specification Limiting Condition for Operation (LCO). The Safety Threshold is set at the technical specification LCO. These thresholds allow room for utility management in the Utility Response Band, and for NRC oversight in the Regulator Response Band before exceeding technical specification limits.
- DATA ELEMENTS AND CALCULATIONS i
RCS activity is determined by conducting analyses in accordance with plant technical specifications and procedures.
RECORDING AND REPORTING On a monthly basis, record highest calculated monthly RCS activity. On a quarterly basis, report the highest calculated monthly RCS activity for each month of the quarter.
TRENDING Plot and trend in monthly increments over a rolling twelve month period.
1 RCS activity greater than the Safety Threshold would be plotted in the " Unacceptable" Band; however, if the utility complied with the technical specification action statements (e.g., shutdown and cooldown within the specified number of hours), the indicator would be reported as " White."
C ATDONENT 4 PDR
SAFETY PERFORMANCE INDICATORS DRAFT 7/27/98 REACTOR COOLANT SYSTEM (RCS) LEAKAGE PURPOSE This indicator deals with protection of the reactor coolant pressure boundary from degradation and the core from inadequate cooling, in addition to preventing the accident analysis radiation release assumptions from being exceeded. The consequences of exceeding the safety threshold
. could include the possibility of a loss of coolant accident.
DEFINITION Reactor coolant system leakage is defined as the total ofidentified and unidentified leakage, as defined in plant technical specifications (TS).
REGULATORY THRESHOLD a Reactor coolant system leakage > 5gpm [or 50% TS identified leakage limit] (PWR)
> 15 gpm (or 50% TS identified leakage limit] (BWR)
SAFETY THRESHOLD 2 Reactor coolant system leakage > 10 gpm [or TS identified leakage limit] (PWR) -
> 30 gpm [or TS identified leakage limit] (BWR)
BASES FOR THRESHOLDS The Regulatory threshold is set at 50% of the technical specification Limiting Condition for Operation (LCO). The Safety Threshold is set at the technical specification LCO. These thresholds allow room for utility management in the Utility Response Band, and for NRC oversight in the Regulator Response Band before exceeding technical specification limits.
DATA ELEMENTS AND CALCULATIONS Reactor coolant leakage is determined by conducting an RCS water inventory balance in accordance with the plant technical specifications and procedures.
RECORDING AND REPORTING On a monthly basis, record highest calculated monthly RCS leakage rate. On a quarterly ,
l basis, repcrt the highest calculated monthly RCS leakage rate for each month of the quarter.
TRENDING Plot and trend in monthly increments over a rolling twelve month period.
a Leakage greater than the Safety Threshold would be plotted in the " Unacceptable" Band; however, if the utility complied with the technical specification action statements (e.g., shutdown and cooldown within the specified number of hours), the indicator would be reported as " White."
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. t l SAFETY PERFORMANCE INDICATORS DRAFT 7/27/98 ;
CONTAINMENT LEAKAGE RATE l PURPOSE This indicator deals with the integrity of the containment barrier in withstanding the pressures and temperatures of postulated design basis accidents without exceeding design leakage rates.
DEFINITION
' Containment leakage rate is defined as a percentage of L., which is the maximum allowable ,
containment leakage rate at the calculated peak containment internal pressure resulting from a limiting design basis accident.
i REGULATORY THRESHOLD TBD SAFETY THRESHOLD 3 L. > 1.0 BASES FOR THRESHOLDS The Regulatory threshold is set at . The Safety Threshold is set at the technical
! specification LCO. These thresholds allow room for utility management in the Utility Response Band, and for NRC oversight in the Regulator Response Band before exceeding ,
l technical specification limits.
DATA ELEMENTS AND CALCULATIONS Containment leakage is determined by conducting leakage rate testing in accordance with plant technical specifications and procedures.
! RECORDING AND REPORTING l
l On a quarterly basis, record and report the highest calculated value of total containment i 1:akage as a percentage of L..
TRENDING
! The data provided will be plotted and trended in quarterly increments over a rolling three year period.
8 Containment leakage greater than the Safety Threshold would be plotted in the " Unacceptable" Band; however, if the utility complied with the technical specification action statements (e.g., shutdown and cooldown within the specified number of hours), the indicator would be reported as " White."
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SAFETY PERFORMANCE INDICATORS DRAFT 7/27/98 UNPLANNED AUTOMATIC SCRAMS PER 7,000 HOURS CRITICAL PURPOSE This indicator deals with undesirable and unplanned thermal-hydraulic and reactivity transients which require automatic reactor scrams and represent challenges to plant safety systems.
DEFINITION The indicator is denned as the number of unplanned automatic scrams that occur per 7,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> of critical operation. (The WANO/INPO definition is used.)
REGULATORY THRESHOLD Unplanned automatic scrams > 3 per year (rolling 12 month period)
SAFETY THRESHOLD Unplanned automaiic scrams > 10 per year (rolling 12 month period)
BASES FOR THRESHOLDS The NRC IPE database shows average CCDP of 1 x 104/ scram. The regulatory threshold
- provides room for utility management to address the low safety challenge represented by three or fewer unplanned automatic scrams. The safety threshold is set at a level above which, for a typical plant, the NRC's subsidiary objective of 1 E-4 is approached.
DATA ELEMENTS AND CALCULATIONS Unplanned automatic scrams per 7,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> critical is determined using the WANO Performance Indicator Program Utility Data Coordinator Reference Notebook.
RECORDING AND REPORTING i
On a quarterly basis, determine and report the unplanned automatic scrams per 7,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> critical for the .past twelve month period.
TRENDING '
The data provided will be plotted and trended in quarterly increments over a rolling three year period.
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SAFETY PERFORMANCE INDICATORS DRAFT 7/27/98 SAFETY SYSTEM ACTUATIONS PURPOSE This indicator provides an indication of the rate at which plant safety systems are challenged.
DEFINITION Safety system actuations are the manual or automatic actuation of the logic for certain emergency cooling systems (for PWRs: high pressure injection, low pressure injection, or safety injection tanks; for BWRs: high and low pressure coolant injection, high and low pressure core spray), and actuations of the emergency ac power system that are caused by loss-of power to a vital bus. Not included are safety system actuations resulting from errors in conducting maintenance and surveillance activities.
REGULATORY THRESHOLD Safety systems actuations > 3 per year (rolling 12 month period)
SAFETY THRESHOLD Safety syst.em actuations > 8 per year (rolling 12 month period)
BASES FOR THRESHOLDS Safety system actuations do not have a direct linkage to PSA or the NRC IPE database. The regulatory threshold is set to' reflect performance met by the 95th percentile of plants in the 1991 to 1997 time frame and provides room for utility management to address the low safety challenge represented by the low number of actuations. The safety threshold is set to reflect performance met by the 95th percentile of plants in 1985 to 1990 time frame.
DATA ELEMENTS AND CALCULATIONS Safety system actuations are recorded and reported in accordance with NRC regulations and plant procedures. Actuations as a result of maintenance or surveillance error are not included.
RECORDING AND REPORTING On a quarterly basis, determine and report the number of safety system actuations.
TRENDING A rolling 4 quarter total will be plotted quarterly and trended over a three year period.
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SAFETY PERFORMANCE INDICATORS DRAFT 7/27/98 i
! SHUTDOWN OPERATING MARGIN PURPOSE 1
! This indicator provides a measure of the safety effectiveness of shutdown operations in maintaining adequate water inventory and cooling to prevent damage to the reactor core.
DEFINITION Shutdown operating margin is assessed in terms of the number ofloss of margin events, and . ,
tha severity of those events in which margin is lost. The loss of margin is measured in terms of '
tha Severity Index, which is the fraction of the available thermal or inventory margin lost during an event.
l REGULATORY THRESHOLD
( . Number ofloss of margin events > 1 per outage Any event with Severity Index > 0.2 l
SAFETY THRESHOLD Number ofloss of margin events > 3 per outage i Any event with Severity Index > 1.0 i BASES FOR THRESHOLDS l
l Loss of coolant inventory or loss of decay heat removal capability are avoided by effective l planning, operations and contingency planning (as described in NUMARC 91-06), and by
! prompt corrective action should a loss occur. The Regulatory threshold is set recognizing that an event can occur even at the best plants. However, should more than one event occur during l- an outage, NRC oversight is appropriate, and more than three events suggests that performance is not acceptable. The severity index measures the amount of margin lost during en event between the initiating parameters and an unsafe condition (212 degrees Fahrenheit or the core uncovered). The regulatory threshold is set at 0.2 (relatively minor safety significance 4). The safety threshold is set at 1.0.
i DATA ELEMENTS AND CALCULATIONS The Severity Index for a shutdown loss of cooling or inventory is determined by the fraction of the available thermal or inventory margin lost before the incident is terminated. For example, if the reactor coolant system heated up 30 degrees Fahrenheit from an initial temperature of 140 degrees, the thermal margin used would be 30/(212-140) = 0.42.
- As discussed in EPRI TR 109014 "An Analysis of Loss of Decay Heat Removal Trends (1989-1996)"
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SAFETY PERFORMANCE INDICATORS DRAFT 7/27/98
( RECORDING AND REPORTING l
On a quarterly basis, ifin an outage, record and report number ofloss of margin events in the current outage, and the maximum severity index which occurred.
TRENDING The data provided will be plotted and trended for the last three outages.
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l l SAFETY PERFORMANCE INDICATORS DRAFT 7/27/98 UNANTICIPATED OPERATING TRANSIENTS GREATER THAN 15% POWER PURPOSE This indicator tracks the total number of unanticipated challenges to the plant that result from a power change greater than 15%. It provides an indication of the stability of plant operations.
DEFINITION The number of unanticipated changes in power of greater than 15%, excluding unplanned automatic scrams which are counted separately.
REGULATORY THRESHOLD TBD )
SAFETY THRESHOLD TBD l 1
BASES FOR THRESHOLDS {
l The number of plant transients (excluding unplanned automatic scrams counted elsewhere) do not have a direct relation to PSA. However, minimizing the number of thermal hydraulic '
challenges to the plant is beneficial. The regulatory threshold is set to reflect performance met by the 95th percentile of plants in the 1990 to 1995 time frame and provides room for utility management to address the low safety challenge represented by the low number of actuations.
The safety threshold is set to reflect performance met by the 95th percentile of plants in 1985 to 1990 time frame.
DATA ELEMENTS AND CALCULATIONS All unplanned plant transients exceeding 15% power except unplanned automatic scrams.
Plant transients purposefully initiated (e.g., surveillance, load following, valve testing, etc.)
would not be included.
RECORDING AND REPORTING On a quarterly basis, record and report number of unplanned transients > 15% power. I
' l TRENDING I
A rolling 4 quarter total will be plotted quarterly and trended over a three year period.
8 C-_ _______.___________m. _ _ _ _ _ _ _ . _ _
c.
SAFETY PERFORMANCE INDICATORS DRAFT 7/27/98 l
l HIGH RISK SIGNIFICANT SSC PERFORMANCE PURPOSE This indicator provides a measure of the mitigation capability of the plant. Operating events can be minimized but not totally eliminated. Engineered safety features were designed to provide reasonable assurance that operating events could be mitigated so as not to breach the barriers to the release of radioactivity to the environment. These indicators measure the plant's perforruance in maintaining mitigation capability.
DEFINITION High risk-significant SSC's and their performance criteria are defined in accordance with the
. Maintenance Rule (10 CFR 50.65) and NUMARC 93-01.
REGULATORY THRESHOLD Plant specific performance criteria established as part of the plant's nv intenance rule implementation for each high-risk significant SSC.
SAFETY THRESHOLD Performance degradation for any single SSC that would cause the Regulatory Guide 1.174 d: cision criteria for NRC review to be exceeded.
B.ASES FOR THRESHOLDS These thresholds allow room for utility management in the Utility Response Band, to perform analysis and corrective action to maintain performance consistent with established performance criteria, and for NRC oversight in the Regulator Response Band before SSC d: gradations of safety significance.
DATA ELEMENTS AND CALCULATIONS In accordance with Maintenance Rule and plant procedures.
RECORDING AND REPORTING Quarterly record and report value of the performance criteria parameter (s) for each high risk-significant SSC.
TRENDING Trend quarterly data over a rolling three year period.
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. . 4 SAFETY PERFORMANCE INDICATORS DRAFT 7/27/98 PLANT PERFORMANCE TREND PURPOSE This indicator provides an overall measure of plant performance. Successful nuclear power plants show strong safe, reliable, and economic performance. This composite index of several 1 indicators of safety, availability anu reliability can be trended over time to show the direction i in which overall performance is heading. l DEFINITION The plant performance trend is a combined index based on a set of safety, availability and ,
reliability indicators. These indicators are: )
i Unit Capacity Factor Forced Outage Rate ,
Unplanned Automatic Scrams )
Safety System Actuations Safety System Failures Significant Events !
Unanticipated Operating Transients Greater than 15%
Equipment Forced Outages per 1000 Hours Collective Radiation Exposure REGULATORY THRESHOLD None. This indicator provides a trend only.
SAFETY THRESHOLD
- None. This indicator provides a trend only.
BASES FOR THRESHOLDS Not applicable.
l DATA ELEMENTS AND CALCULATIONS Calculate the following indicators as follows:
Unit Capacity Factor - per Monthly Report Forced Outage Rate - per Monthly Report Unplanned Automatic Scrams - per WANO/INPO instructions Safety System Actuations - per AEOD indicators Safety System Failures - per AEOD indicators Significant Events - per AEOD indicators 10
SAFETY PERFORMANCE INDICATORS DRAFT 7/27/98 Unanticipated Operating Transients > 15% - per this paper
- Equipment Forced Outages /1000 Hrs- per AEOD indicators Collective Radiation Exposure - per AEOD indicators Method to index indicators is under development.
RECORDING AND REPORTING The index is calculated and reported on a quarterly basis.
TRENDING Trend over a three year period. ,
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