ML20137C858
| ML20137C858 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 03/18/1997 |
| From: | VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | |
| Shared Package | |
| ML20137C857 | List: |
| References | |
| NUDOCS 9703250149 | |
| Download: ML20137C858 (6) | |
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1 REACTOR COOLANT SYSTEM BASES 3/4.4.6 REACTOR COOLANT SYSTEM LEAKAGE 3/4.4.6.1 LEAK AGE DETECTION SYSTEMS The RCS leakage detection systems required by this specification are provided to monitor and detect leakage from the Reactor Coolant Pressure Boundary during normal plant operations and after seismic events to provide prompt and quantitative information to the operators to permit immediate corrective actions should a Reactor Coolant Pressure Boundary leak be detrimental to the safety of the facility.
These detection systems are generally consistent with the recommendations of Regulatory Guide 1.45," Reactor Coolant Pressure Boundary Leakage Detection Systems," May 1973. The containment atmospheric particulate and gaseous radioactivity monitoring system is not fully seismically qualified. Consistent with RG 1.45 these monitors can perform their intended function during normal plant operations. To ensure the safety function of detecting reactor coolant pressure boundary leakage is maintained after a seismic event the operability of these monitors is required to be verified immediately following a seismic event or the affected units will be shut down and cooled down to COLD SHUTDOWN.
3/4.4.6.2 OPERATIONAL LEAKAGE Industry experience has shown that while a limited amount of leakage is expected from the RCS, the unidentified portion of this leakage can be reduced to a threshold value of less than 1 GPM. This threshold value is sufficiently low to ensure early detection of additional leakage.
The 10 GPM IDENTIFIED LEAKAGE limitation provides allowance for a limited amount of leakage from known sources whose presence will not interfere with the detection of UNIDENTIFIED LEAKAGE by the leakage detection systems.
The surveillance requirements for RCS Pressure Isolation Valves provide added assurance of valve integrity thereby reducing the probability of gross valve failure and consequent intersystem LOCA. Leakage from the RCS Pressure Isolation Valves is IDENTIFIED LEAKAGE and will be considered as a portion of the allowed limit.
The CONTROLLED LEAKAGE limitation restricts operation when the total flow supplied to the reactor coolant pump seals exceeds 30 GPM with the modulating valve in the supply line fully open at a nominal RCS pressure of 2235 psig. This limitation ensures that in the event of a LOCA, the safety injection Dow will not be less than assumed in the accident analyses.
The total steam generator tube leakage limit of 1 GPM for all steam generators not isolated from the RCS ensures that the dosage contribution from the tube leakage will be limited to a small fraction of Part 100 limits in the event of either a steam generator tube rupture or steam line break.
The 1 GPM limit is consistent with the assumptions used in the analysis of these accidents. In general, for plant operation at or below 50% power, the 500 gpd leakage limit per steam generator ensures that steam generator tube integrity is maintained in the event of a main steam line rupture or under LOCA conditions.
NORTH ANNA - 11 NIT 2 9703250149 970318 B 3/4 4-4 Amendment No. 95, PDR ADOCK 05000338 P
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BASES 3/4.4,6 REACTOR COOLANT SYSTEM LEAKAGE 3/4.4.6.1 LEAKAGE DETECTION SYSTEMS The RCS leakage detection systems required by this specification are provided to monitor and detect leakage from the Reactor Coolant Pressure Boundary during normal plant operations and after seismic events to provide prompt and quantitative information to the operators to permit immediate corrective actions should a Reactor Coolant Pressure Boundary leak be detrimental to the safety of the facility.
These detection systems are generally consistent with the recommendations of Regulatory Guide 1.45," Reactor Coolant Pressure Boundary Leakage Detection Systems " May 1973. The containment atmospheric particulate and gaseous radioactivity monitoring system is not i
fully seismically qualified. Consistent with RG 1.45 these monitors can perform their intended function during normal plant operations. To ensure the safety function of detecting reactor coolant pressure boundary leakage is maintained after a seismic event the operability of these monitors is required to be verified immediately following a seismic event or the affected units will be shut down and cooled down to COLD SHUTDOWN.
3/4.4.6.2 OPERATIONAL LEAKAGE Industry experience has shown that while a limited amount ofleakage is expected from the RCS, the unidentified portion of this leakage can be reduced to a threshold value ofless than 1 GPM. This threshold value is sufficiently low to ensure early detection of additional leakage.
The 10 GPM IDENTIFIED LEAKAGE limitation provides allowance for a limited amount of leakage from known sources whose presence will not interfere with the detection of UNIDENTIFIED LEAKAGE by the leakage detection systems.
The CONTROLLED LEAKAGE limitation restricts operation when the total flow supplied to the reactor coolant pump seals exceeds 30 GPM with the modulating valve in the supply line fully open at a nominal RCS pressure of 2235 psig. This limitation ensures that in the event of a LOCA, the safety injection flow will not be less than assumed in the accident analyses.
The total steam generator tube leakage limit of 1 GPM for all steam generators not isolated from the RCS ensures that the dosage contribution from the tube leakage will be limited to a small fraction of Part 100 limits in the event of either a steam generator tube rupture or steam line break. The 1 GPM limit is consistent with the assumptions used in the analysis of these accidents. In general, for plant operation at or below 50% power, the 500 gpd leakage limit per steam generator ensures that steam generator tube integrity is maintained in the event of a main steam line rupture or under LOCA conditions.
NORTH ANNA - UNIT 1 B 3/4 4-4 Amendment No. 409,
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Commitments Commitment to provide seismically qualified containment gaseous and particulate radiation monitors to detect reactor coolant leakage is modified to provide non-seismicaily qualified containment gaseous and particulate radiation monitors and immediately verify monitor operability by procedure after a seismic event or place the affected unit in Cold Shutdown.
Commitments i
Commitment to provide seismically qualified containment gaseous and particulate radiation monitors to detect reactor coolant leakage is modified to provide non-seismically qualified containment gaseous and particulate radiation monitors and immediately verify monitor operability by procedure after a seismic event or place the affected unit in Cold Shutdown.
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Commitments Our commitment to provide a seismically the Containment Gaseous and Particuhte Radiation Monitoring System to detect reactor coolant leakage is modified to provide a non-seismically the Containment Gaseous and Particulate Radiation Monitoring System and immediately verify monitor operability by procedure after a seismic event or place the affected unit in Cold Shutdown.
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