ML20039G517
| ML20039G517 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 01/07/1982 |
| From: | Beckham J GEORGIA POWER CO. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.K.3.15, TASK-TM NUDOCS 8201180350 | |
| Download: ML20039G517 (2) | |
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January 7, 1982 Georgia Power e,nu n ce s J. T. Beckham, Jr.
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20555 JMIS q w c NRC DOCKETS 50-321, 50-366 Y
s an s men e m Y OPERATING LICENSES DPR-57, PPF-5 WC ED#IN I. HATCH NUCLEAR PLANT UNITS 1, 2 CJ NUREG-0737, ITEM II.K.3.15 Gentlemen:
oi Georgia Power Company hereby sucmits the fallowing information in response to your letter dated October 19, 1981, concerning NUREG-0737, Item II.K. 3.15.
Time delay relays have been installed in the steam supply line break isolation logic on the HPCI and RCIC systems on the Hatch units.
The ability of the time delay relays on the high differential pressure switches (on the steam supply line) to prevent spurious isolations is demonstratrJ oy the fact that no spurious Hi Differential Pressure isolations have occurred on any of the HPCI and RCIC systems since the installation of a three second time delay.
Prior to the installation of the time delays, numerous system isolations occurred during the system operability tests, including once in 1979 on Unit 2 when both 9PCI and RCIC spuriously isolated following a reactor scram.
The Unit 2 RCIC time delays have been installed since 1979.
Time delays were installed on the Unit 2 HPCI, Unit 1 RCIC, and Unit 1 HPCI systems in June 1981.
Technical Specification changes will not be submitted based upon past discussions with NRC Region II and tRR personnel concerning the installation of time delay relays in the isolation logic.
It was mutually agreed that existing Technical Specifications provided for a delay of thirteen seconds, and as long as the time delay relay timed out before thirteen seconds no change to Technical Specifications was required.
The thirteen seconds is based on the loss of offsite power scenario with a failure of the DC powered isolation valve.
The timer.s added to the relays are powered such that the time delay is not added into the time delay due to the diesel start sequence.
Surveillance of the HPCI/RCIC time delays is already provided for in the existing Technical Specifications.
Technical Specifications require that a system functicnal test be performed once per operating cycle.
This test includes simulated automatic actuation of the system throughout its emergency operating sequence and verifies that each automatic valve in the flow path actuates to its correct position.
During the course of the logic system functional test (LSFT), the subject time delay relays are activated and timed out. Delay time is specified in the plant surveillance procedures for the HPCI/RCIC LSFTs.
Actual delay time is recorded and maintained as part of permanent plant records.
The LSFT includes calibration of time delay relays and timers necessary for proper functioning of the trip system.
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Georgia Pbwer b Director of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 January 7, 1982 Page Two The safety function of the primary system isolation has not been degraded as a result of the modification.
The installation of time delays of three seconds will have no affect on analyses previously completed to assess the effects of a break in the iPCI or RCIC system supply lines.
Anajyses have assumed a thirteen second delay prior to the start of the AC valve closure.
This delay is based on the time required to start and load the emergency diesel generators in the event of a loss of offs'te power.
In addition, it has also been assumed that the DC isolation valve fails to close.
This chain of events requires that a steam blowdown duration of thirteen seconds plus the valve closure time be considered in the analysis.
Timer circuitry will be unaffected by a loss of offsite power; therefore, it will be timed out prior to the AC isolation valve receiving nower to close and will not affect the blowdown or the analytical results.
If there is no loss of offsite power, the AC and DC isolation valves will have a closure signal delay of three seconds, but will still close prior to the time assumed in the analysis since emergency diesel generator start time need not be considered.
The duration of the blowdown will be shorter than that postulated in the analysis and the effects of the blowdown less severe.
If you have any questions in this regard, please contact this office.
J. T. Beckham, Jr. states that he is Vice President of Georgia Power Company and is authorized to execute this oath on behalf of Georgia Power Company, and thet to the best of his knowledge and belief the facts set forth in this letter are true.
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GEORGIA POWER COMPANY i
By 1
J. T. Beckham, Jr. /
Sworntoandsubscribedbeforemethis7thdayofJanuag,1982.
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M. Manry R. F. Rogers, III L.