ML20045H413
| ML20045H413 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 07/12/1993 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 93-067A, 93-67A, NUDOCS 9307200185 | |
| Download: ML20045H413 (5) | |
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VInOINIA ELucinic Axn Pownn COMPANY HIcitMoxu, VInotx1A 20201 July 12, 1993 U.S. Nuclear Regulatory Commission Serial No.
93-067A Attention: Document Control Desk NL&P/JBL:
R2 Washington, D.C. 20555 Docket Nos.
50-338 50-339 License Nos. NPF-4 NPF-7 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 SERVICE WATER SYSTEM RESTORATION PROJECT WITHDRAWAL OF GDC-2 EXEMPTION REQUEST i
By letter dated February 17,1993 (Serial No.93-067), Virginia Electric and Power Company requested a temporary exemption from the requirements of 10 CFR Part 50, Appendix A, Criterion 2 (GDC-2), to allow excavation around certain portions of the service water piping during the upcoming Unit 2 refueling outage (currently scheduled to begin September 4,1993). Based on further evaluation, the project schedule has been revised and the scope of work to be performed during this outage has been reduced. Consequently, the requested exemption from the iequirements of GDC-2 will not be needed. Therefore, we withdraw our request for a temporary exemption from the requirements of GDC-2 for the excavation effort previously associated with the 1993 Unit 2 refueling outage. The following information is provided in explanation of our decision.
Phase I, Stage 1 of the service water system restoration project was accomplished during the recent Unit 1 steam generator replacement outage. Stage 1 of the project involved repair and/or replacement of the service water piping to the Unit 1 containment recirculation spray heat exchangers. Phase I, Stage 3 of the project is intended to provide for repair and/or replacement of similar sections of the 24-inch service water piping to the Unit 2 containment recirculation spray heat exchangers. As discussed in our Februaly 17,1993 letter, several repair and construction approaches were being evaluated for Stage 3 of the project to determine the most feasible method of refurbishing these service water lines. The primary focus of this evaluation was to accomplish the refurbishment with minimum regulatory relief while maintaining the necessary safety margin during the construction activities.
I We have concluded that most areas of the service water piping to the Unit 2 recirculation spray heat exchangers do not require repairs during the 1993 refueling outage. With one exception, our evaluation of the results of the Unit 1 pipe repair and j
replacement effort concluded that the service water system has adequate integrity to I
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1 justify reschedul.ing the final refurbishment of the four Unit 2 service water lines to a future outage or outages; The scope of work required to be performed during the 1993 Unit 2 refueling outage will include inspection and repair of localized areas near pipe circumferential weld joints in the four service water lines. In addition, certain sections'-
of auxiliary service water return lines to the Unit 2 circulating water tunnel located in i
the turbine building valve pit'will be repaired or replaced during the outage. in 3
clarification of the proposed work plan described in our February 17,1993 submittal,L our evaluation has concluded that the repair and/or replacement of the auxiliary service water return lines in the turbine building valve pit may be performed either
.during the 168-hour Action Statement or with the service water piping in normal operation. Appropriate contingency measures will be in place for this work effort during either system operating condition.
Although the service water piping in the alleyway need not be excavated for this reduced scope-of work, four entries into the 168-hour Action Statement will be required for installation and removal of pipe plugs in the service water lines to the Unit
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2 recirculation spray heat exchangers. Because multiple entries into the 168-hour Action Statement will be-required, we have developed appropriate compensatory actions and contingency measures to ensure availability of required safety functions.
in addition, appropriate compensatory actions and contingency measures have been f
developed for the work on the auxiliary service water piping in the turbine building.
- l valve pit. A_ list of the contingency measures has been excerpted from our February 17,1993 submittal and is provided as an attachment to this letter.
North Anna Unit 2 is scheduled to conclude the current cycle of operation and begin a refueling outage on September 4,1993. As previously identified, the requested temporary exemption from GDC-2 for a period of time beginning approximately 30 days prior to and ending approximately 30 days following the Unit 2 outage will not be
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required for this outage. The remainder of Phase I, Stage 3 of the service water.
restoration project will be rescheduled for a future outage or outages. A. separate exemption request (similar to our February 17,1993 letter) will be submitted in support this work effort, if necessary. Such an exemption request would be provided to the NRC as soon as possible following the development of the construction plans.
If you have any questions or require any additionalinformation, please contact us.
Very truly yours, Y
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W. L. Stewart Senior Vice President - Nuclear Attachment J
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cc:
U.S. Nuclear Regulatory Commission Region ll 101 Marietta Street, N.W.
Suite 2900 Atlanta, Georgia 30323 Mr. D. R. Taylor NRC Resident inspector North Anna Power Station 6
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Attachment s
and Contingency Measure work involved with the limited scopeject to Compensatory Actions r
water system restoration pro e considered to take the extra-ordinary circumstancesi d of time. The purpose of 3 of the service Unit 2 refueling outage that ar ke is to plan for those risks and are two l of risk for a temporary per o activities for Phase I, Stage There performed during the 1993 plant to a relatively and contingency measuresfe operation of the p it 1 is in Mode 1 power compensatory actionsnecessary steps to ensure sa tion Statement when Un auxiliary service Four entries into the 168 hour0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> Acin Mode 5 or
.are:
d C43 in the vicinity of operating
- operation and Unit 2is i g valve pit.
'9 placement of Lines C42 annd 425 in the turbine b rios, compensatory These tivities and possible scenaestablished 9r Unes 25,58,59, a a careful review of these ac s have been
.7ntingency measuretingency measures are:
^tions and con water water or fire hould z +h primary gradethe charging pump ver supply from ither the
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e milable as a. contingency torater supply eas to reduce response d
materials will be staged in key a ture.
?re developed and plant pe t ol room / emergency id materials.
m the Unit 1 bearin flow path to the Unit 1 con r air-conditioning chillers fro ply to the Unit 1f de available,if required. In water, a back-up water sup f
i rovide additional reliabilty
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water J!aly.fLEit water or fireolers sh the'. primary grade icy to the charging pump co
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/ESGR air-condition bpted.
o the" Unit.1 CR J er system ill be ma w
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Attachment Compensatory Actions and Contingency Measures There are two extra-ordinary circumstances involved with the limited scope work activities for Phase 1, Stage 3 of the service water system restoration project to be performed during the 1993 Unit 2 refueling outage that are considered to take the plant to a relatively higher level of risk for a temporary period of time. The purpose of compensatory actions and contingency measures is to plan for those risks and take 3
necessary steps to ensure safe operation of the plant. The two unusual circumstances are:
Four entries into the 168-hour Action Statement when Unit 1 is in Mode 1 power operation and Unit 2 is in Mode 5 or 6.
Replacement of Lines C42 and C43 in the vicinity of operating auxiliary service I
water Lines 25,58,59, and 425 in the turbine building valve pit.
Based upon a careful review of these activities and possible scenarios, compensatory actions and contingency measures have been established for this project. These compensatory actions and contingency measures are:
Durina the 168-hour Action Statements A temporary water supply from either the primary grade water or fire water systems will be available as a contingency to the charging pump coolers should the normal service water supply be interrupted.
Emergency pipe repair materials will be staged in key areas to reduce response time in the event of a service water pipe leak or rupture.
Procedures for emergency pipe repairs are developed and plant personnel will be trained in the use of these procedures and materials.
A back-up supply and return flow path to the Unit 1 control room / emergency switch gear room (CR/ESGR) air-conditioning chillers from the Unit 1 bearing cooling water system will be made available, if required. In the low probability event of a total loss of service water, a back-up water supply to the Unit 1 CR/ESGR chillers is considered to provide additional reliability for the CR/ESGR air-conditioning system.
During Work Activities in the Turbine Building Valve Pil A temporary water supply from either the primary grade water or fire water systems will be available as a contingency to the charging pump coolers should the normal service water supply be interrupted.
A back-up supply and return flow path to the Unit 1 CR/ESGR air-conditioning chillers from the Unit 1 bearing cooling water system will be made available, if Page 1 of 2
required. In the low probability event of a total loss of service water, a back-up water supply to the Unit 1 CR/ESGR chillers is considered to provide additional reliability for the CR/ESGR air-conditioning system.
Motor-operated valves on Lines 58 and 59 will be administrative!y locked closed.
This work activity will be scheduled so that it is not in progress when periodic testing of system components or when service water system make-up from the.
auxiliary service water pumps is required.
t Communication between the control room and the turbine building valve pit will be maintained during the work activities in the valve pit. The control room operator will be informed of the work in progress at shift change.
In addition, during the disassembly or reassembly of components (i.e.,_ pipe sections, valves, expansion joints) in the turbine building valve pit, an operator will be stationed at the service water pump house with direct communications to the turbine building valve pit. The operator could be directed to isolate the affected service water header immediately should the need arise.
Materials and tools necessary for performing emergency repair of pressurized pipe will be staged near the turbine building valve pit. Procedures for emergency pipe repairs are developed and plant personnel will be trained in the use of these procedures and materials.
Lifting and rigging components will be inspected and load tested.
Pre-job briefing will be conducted for the intended route of removed or new pipe sections with the emphasis placed on "importance-to-safety" of keeping these pipe sections below the pressurized piping.
Pressurized auxiliary service water piping will be. covered with a protective blanket to minimize the impact of a blow from a heavy object.
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