ML20073M236
| ML20073M236 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 04/15/1983 |
| From: | Beckham J GEORGIA POWER CO. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.K.3.28, TASK-TM NED-83-253, TAC-48277, TAC-48278, NUDOCS 8304210454 | |
| Download: ML20073M236 (7) | |
Text
Georgia Power Company 333 Piedmont Aw.nue Atlanta. Georg a 30308 Telephone 404 526-7020 Mailing Address-Post off(,e Box 4545 Atlanta. Georgra 30302 Georgia Power J. T. Beckham, Jr.
vice President and Generat Manager NED-83-253 Nuclear Generation April 15, 1983 Director of Nuclear Reactor Regulation Attention: Mr. John F. Stolz, Chief.
Operating Reactors Branch No. 4 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D. C.
20555 NRC DOCKETS 50-321, 50-366 OPERATItG LICENSES DPR-57, FFF-5 EDWIN I. HATCH NUCLEAR PLANT UNITS 1, 2 NUREG-0737 ITEM II.K.3.28 - VERIFY QUALIFICATION OF ACCUMULATORS ON AUTOMATIC DEPRESSURIZATION SYSTEM VALVES Gentlemen:
By your letter of February 8,
1983, Georgia Power Company (GPC) was
. requested to provide additional information to enable the NRC staff to complete its review of the subject NUREG-0737 item.
Our response to this request is attached as Enclosure 1.
Please contact this office if there are any questions.
3 Very truly yours,
}_k.--
_S, -
J. T. Beckham, Jr.
JH/mb Enclosure xc: (all w/ enc 1)
H.C. Nix, Jr.
J.P. O'Reilly (NRC-Region II)
Senior Resident Inspector 8304210454 830415 PDR ADOCK 05000321 P
EtCLOSURE 1 ADDITIONAL INFORMATION REGARDIPO NUREG 0737 ITEM II.K.3.28 QUALIFICATION OF ACCUMULATORS ON AUTOMATIC DEPRESSURIZATION SYSTEM VALVES
. The - NRC - (J.F. Stolz) letter to Georgia Power Company.. (J.T. Beckham, Jr.)
dated February 8, 1983 requested additional information to enable the NRC staff to complete.its review of NUREG 0737 Item II.K.3.28. For the purpose of. responding to this letter the following definitions are made:
An ADS accumulator system is defined as an ADS Safety / Relief Valve
-(SRV),.Its solenoid-operated control valves. and
- circuits, its accumulator, the accumulator drain valve, the check valve at the inlet
' to the - accumulator, the interconnecting piping, and the supports for these components. A schematic diagram of an ADS accumulator system is provided as Figure 1. There are seven of these systems in each of the Hatch Units.
Backtp system is defined as the Nitrogen Systen which supplies the ADS accumulator systems.
Modifications. to improve the backup system are currently in progress at Plant Hatch Units 1 and 2; however, credit for these improvements is not taken in the following responses:
Item 1 Define the basis for the allowable leakage criteria for the ADS accumulator system ' (e.g., boundary conditions, environmental, and seismic parameters, operator interface, margin, etc.).
Response to Item 1
~
The ADS accumulators are sized to provide at least two. ADS S/RV actuations with the drywell at 70% of its design pressure. The' allowable leakage criteria ensures this capability for up to 1/2 hour following loss of the pneumatic supply to the accumulators.
4 Actuation off the ADS valves' is automatic; however, actuation of ADS or of any S/RV can be accomplished manually if necessary.
The following margins are., included in the Hatch ADS design:
The accumulators are sized to provide at least two actuations of each of the seven ADS valves during the first 1/2 hour following loss of the pneumatic supply to the accumulators; only one actuation of any three ADS valves is needed for depressurization.
.----a
'The allowable accumulator system leakage rate to be proposed for inclusion in Technical Specifications is based on the drywell being at 70% of Its design pressure or 43.4 PSIG. This drywell pressure results from the largest break for which ADS would be needed. As further mitigation, in accordance with the Hatch Mark I Containment Long Term Program and the. BWR Owners Group Emergency Procedures Guidelines, the operator will be directed to either depressurize the vessel by use of the S/RVs or take action to reduce drywell pressure if the pressure were to exceed 17 PSIG.
This action will limit the rise in drywell pressure due to the break and will effectively extend the accumulator availability -because a ' lower accumulator pressure will be adequate to actuate an ADS valve. For example, if the drywell pressure is limited to 33.4 PSIG, accumulator availability' would be extended to more than one hour.
Seismic and environmental parameters are addressed in the responses to Items 2,3,12, and 13.
Item 2 What margin is in the allowable leakage criteria to account for possible increase in leakage resulting from the effects of a harsh environment and/or a seismic event.
Response to Item 2
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The ADS accumulator systems are designed to Seismic category I requirements.
The check valves are soft-seated, spring loaded piston type valves which were. specified' for the harshi environment. There 'is no known m'echanism for either a seismic event or a ha'rsh_ environment-to increase leakage from these systems. We believe the ^ margin discussed in the response to Item 1 is sufficient to handle any uncertainties in this regard.
Item 3 A statement that test and/or analysis performed verified that a harsh environment and/or a seismic event would not increase the leakage rate.
Response to Item 3 The applicable components were procured to meet seismic and environmental qualification criteria which included appropriate testing.
-Item 4
~ A statement that verifies that no credit was taken for non-safety related equipment and instrumentation when establishing the allowable leakage criteria.
s.
Response to Item 4 No credit was taken for non-safety releted. equipment and instrumentation when establishing the allowable leakage criteria.
t Item 5 Define the periodic leak testing of the ADS accumulator system (i.e.,. the time interval between these leak tests, along with a concise description-of the test procedure employed).
Response to Item 5 Leak tests will be performed on.all ADS accumulator systems at least once per operating cycle, following adoption _of the Technical Specifications described in the response to Item 11. The leak test first requires venting of the pneumatic supply header upstream cf check valve F036 (Refer to Figure 1). A test pneumatic supply is then applied at the accumulator drain valve (F076). The. makeup > flow required to maintain the accumulator system pressure is measured in order to determine the total assembly. leakage rate.-Since the accumulator drain valveis normally closed and capped, leakage through the valve seat and cap will not be tested.
Item 6 Provide a concise description of the design and operation of the backup system and confirm that it will meet the overall requirements of the ADS system.
Response to Item 6 Georgia Power Company's interpretation of the overall requirements of the ADS system was provided in our December 30, 1981 submittal. Also in that submittal was a description of the design and operation of the backup system and confirmation that it met those requirements.
Item 7 A concise description of the alarms and instrumentation associated with the ADS accumulator system and backup system, if applicable.
Response to Item 7 There - are no alarms or instrumentation directly associated with an ADS accumulator system.
Low pressure and high pressure alarms are provided in the pneumatic header which supplies the ADS accumulator systems to alert the operator if the accumulators are not being properly charged.
Item 8 A concise description of the tests performed on the backup system and their frequency.
p.
Response to Item 8 Functional testing will be performed on all _ active components of.the. backup -
system during every refueling outage.
Item 9 A concise description of the surveillance. performed, and how frequent, on -
alarms associated with the ADS accumulator system and ' backup system, if applicable.
Response to Item 9 There are no alarms directly associated with an ADS accumulator-system. The high and low pressure alarms in the backup system will be functionally tested and calibrated during every refueling outage.
Item 10 A statement that test and/or analysis have verified that leakage will not prevent the ADS from performing as required.
Response to Item 10 An analysis has been performed to determine the maximum allowable accumulator system leakage to ensure ADS valve operability per the criterion provided in the response to Item 1. Leakage less than or equal to this
~
allowable will not prevent the ADS'from performing as required.
Item 11 Excerpts from the plants;. technical specification, verifying that they
..specify the following:
ADS leak test frequency Allowable leakage rate.
Actions to be taken, in a specified time frame, should the allowable leakage rate be exceeded.
Response to Item 11 Plant Hatch Technical Specifications are being revised to require the follo.ving during every refueling outage:
ADS accumulator leak rate testing Allowable leakage rate of 4.5 SCFH Repairs to bring the leakage rate within the allowable range before plant startup
. Item 12 A. statement that confirms. that the ADS. accumulator system, associated-equipment and control circuitry, and backup'. system, if applicable, are seismically qualified.
! Response'to Item 12 designed' to Seismic
. ADS accumulator systems and the backup system are Category I criteria.-
Item-13 A statement that confirms that the ADS accumulator system and ' associated equipment and control circuitry are qualified to accomodate the effects of and. are compatible with the environmental. conditions associated with normal operation, maintenance, testing, and postulated accidents as stated in General Design Criteria 2 and 4 of Appendix A of 10CFR50.
Response to Item 13 The ADS accumulator systems are qualified to accomodate the effects of, and are compatible with the environmental conditions associated with normal operation, maintenance, testing, and postulated accidents as stated in General Design Criteria 2 and 4 of Appendix A to 10CFR50. The electrical components in.the ADS accumulator systems are included in the I&E Bulletin 79-OlB qualification program.
Item 14-A statement verifying-that the ADS valves, accumulators, associated equipment and instrumentation are capable of performing their function during and following an accident situation while taking no credit for non-safety related equipment and instrumentation.-
Response to Item 14 The ADS accumulator systems are capable of performing their function during and following an accident situation while taking no credit for non-safety related equipment and instrumentation.
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