ML20214F933

Forwards Justification for Continued Operation Using Spare Reactor Coolant Pump Motor for One Operating Cycle.Spare Motor Does Not Have Customized Oil Leak Collection Sys, Requiring Interim Leak Collection Arrangement Installation

ML20214F933
Person / Time
Site:	Surry
Issue date:	11/10/1986
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
86-722, NUDOCS 8611250487
Download: ML20214F933 (8)

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l ', *e VIMOINIA ELucTHIC AND Pownu COMPANY RicnwoNn,VINGINIA 20261 W.L.StuwamT EB tm l7 P 1 : 29 VICE I*BENIDENT Noctuan ornumo== November 10, 1986 Dr. J. Nelson Grace Serial No.86-722 Regional Adninistrator N0/JDH:vlh Region II Docket No. 50-281 U.S. Nuclear Regulatory Commission License No. DPR-37 Suite 2900 101 Marietta St., N.W.

Atlanta, Georgia 30323

Dear Dr. Grace:

VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNIT NO. 2 UTILIZATION OF SPARE RCP MOTOR Recent events at Surry Power Station Unit No. 2 have resulted in the need to utilize a spare reactor coolant pump (RCP) motor from the North Anna Power Station for one cycle of operation. This sparc motor does not have a customized oil leak collection system, necessitating that an interim leak collection arrangement be installed. This interim arrangement is necessary to not adversely impact the Unit 2 restart currently scheduled for the end of November 1986.

These actions have been discussed with the NRC Surry Project Manager and the NRC Resident Inspector and were also discussed with NRC Region II representatives on October 30, 1986. This action is similar to that

, implemented during the 1984 Unit I refueling outage, as documented in our November 16, 1984 (Serial No. 665) letter to you and confirmed by your letter dated December 6, 1984.

Our justification for continued operation (JCO) using the interim leak collection arrangement and associated compensatory measures is attached.

The JC0 describes the specific events at Surry which led up to these actions, provides an analysis of the potential consequences of a RCP oil leak, and outlines the compensatory measures that we have taken to further mitigate those consequences.

0611250407 ADOCK 000201 PDR PDR II O

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If you have any questions, or require any additional information, please conta t us immediately.

Very truly yours, y

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b L 'h W. L. Stewart Attachment cc: Mr. Lester S. Rubenstein, Director PWR Project Directorate No. 2 Division of PWR Licensing-A Mr. W. E. Holland NRC Senior Resident Inspector Surry Power Station Mr. Chandu P. Patel NRC Surry Project Manager PWR Project Directorate No. 2 Division of PWR Licensing-A Mr. A. J. Ignatonis .

Division of Reactor Projects NRC Region II Mr. W. H. Miller Engineering Branch NRC Region II

NITACHS1ENT Justification for Continued Operation Surry Power Station Unit No. 2 Utilization of Spare RCP Motor i

Justification for Continued Operation Surry Power Station Unit No. 2 Utilization of a Spare RCP Motor 4

BACKGROUND During the 1986 Unit 2 refueling outage (began October 3,1986; currently scheduled restart is November 25, 1986), a routine inspection by the vendor of the "C" reactor coolant pump (RCP) motor disclosed several j cracks in the RCP motor rotor bar, rendering the motor unacceptable for continued use. Refurbishment of the motor is being conducted, but cannot be completed in time to support the scheduled plant restart. Thus, to not adversely affect the outage schedule, we are pursuing installation of a spare RCP motor currently maintained at our North Anna site. This action is similar to that implemented during the 1984 Unit I refueling outage, as documented in our November 16, 1984 (Serial No. 665) letter to you and confirmed by your letter dated December 6, 1984.

Because the spare North Anna RCP motor is of a different physical configuration than its Surry counterpart, the RCP oil leak collection system currently in place at Surry cannot be used. The oil collection i system for each RCP motor must be custom designed and installed. A design modification to install a new oil collection system for the North Anna

. RCP motor in Surry Unit 2 is not feasible because the modification cannot be completed in time to support restart and would be in place for no more than one cycle of operation. It is our intent to reinstall the refurbished Surry RCP motor at the first outage of sufficient duration subsequent to its return from the vendor, but in any case no later than the next refueling outage, currently scheduled for May 1988.

We have evaluated the consequences of a possible oil leak from a RCP motor lube oil system without the installed oil collection system in place.

We have concluded that the interim oil leak collection arrangement and associated compensatory measures provide a comparable level of safety to that afforded by the normal leak collection system. Our evaluation of the consequences of such an event and the compensatory actions we will take to mitigate those consequences are further discussed below.

EVALUATION

System Description

Each RCP Motor has its own oil collection system including a collection tank. The system was installed in fulfillment of License Condition 3.I, i issued on September 19, 1979, as Amendment No. 53 to Facility Operating License No. DPR-37. The installed oil collection system also meets the intent of 10 CFR Part 50, Appendix R, Section III.0, Reactor Coolant Pump j 011 Collection System.

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The collection system collects and temporarily stores any lube oil which leaks- out of the RCP motor lube oil system. The collection system consists of leak proof pans under and around oil bearing components that mav leak, with covers to contain oil from leaks in pressurized lines and to keep foreign matter out of the drain. Each oil collection enclosure is connected to a header which drains the oil to a tank below the

! enclosures. The tank is equipped with a flame arrestor. Each oil collection tank has a 265 gallon capacity. The approximate oil capacity of each RCP motor is 250 gallons.

Area Description

! The primary containment has.three separate cubicles that contain a steam I

generator and a reactor coolant pump and motor. These cubicles are arranged around the reactor vessel. The cubicle of concern is the "C" cubicle located to the southeast of the reactor vessel. The cubicles have a concrete base at the minus 3 ft. 6 in. elevation. The cubicle walls, l

constructed of reinforced concrete, extend up to the 47 ft. 4 in.

elevation. There are piping penetrations in the cubicle walls as well as the floor. There are access doors to the cubicles at the minus 3 ft.

6 in, and the 18 ft. 6 in. elevations. These doors are somewhat shielded from the rest of the cubicle by a vestibule arrangement.

The "C" cubicle is located on the opposite side (180 degreer,) from the Fuel Building instrumentation penetration and 90 degrees from the Cable

! Vault / Tunnel penetration.

Fire Hazards Analysis i

i j The primary combustible in the Reactor Coolant Pump (RCP) cubicle is j approximately 250 gallons of lubricating oil for the RCP motor. With no oil collection system in place for the "C" reactor coolant pump, a rupture

! of the "C" RCP motor lube oil system could be postulated that would, result i in the discharge of up to 250 gallons of lube oil into the C" RCP cubicle.

i The worst case scenario for the cubicle is a total loss of the lube oil

] and a resulting fire. The following factors, including the interim oil

leak collection arrangement of the cubicle as described below, will

mitigate the effects of this fire scenario

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1) The floor of the cubicle is constructed of reinforcad concrete.

3 There are some pipe penetrations through the floor; however, there i

are steel sleeves forming each penetration that extend approximately l 4 inches above the floor. Based on the floor area of the cubicle and 250 gallons of oil, the depth of the oil would be 0.5 inches, well below the level of the sleeve lip. Four inch dikes will be installed at the doors to prevent oil flow out of the cubicle doors.

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2) Where pipes do penetrate the floor, spray covers will be installed on the pipes extending beyond the penetration sleeves described above. As an alternative, certain penetrations may be filled with 1

fire retardant foam. This will prevent spray through the openings as well as stopping oil flow down the outside of the pipe.

3) The concrete walls of the cubicle extend up to the 47 ft. 4 in.

elevation from the minus 3 ft. 6 in. elevation. There is approximately 15 feet from the top of the RCP motor to the top of the cubicle. This distance will prevent spray out of the cubicle. In addition, oil will collect on the walls or pipes and flow to the concrete base at the minus 3 ft. 6 in. elevation.

4) Heat from a fire will rise in the cubicle to the operating floor (elevation 47 ft. 4 in.). After leaving the cubicle the heat will continue to rise to the top of the containment structure where there are no safe shutdown exposures. In addition, as heat leaves the cubicle it will entrain air, resulting in a cooling effect on the hot gases.

5) Internal obstructions within the cubicle such as walkway grating at the 18 ft. 4 in. elevation, the steam generator, and the approximately 50 ft. distance from the base to the top of the cubicle will prevent flame from leaving the cubicle.

6) Motor problems that could result in a loss of oil can be detected by several existing means: bearing temperature, motor vibration, and motor running current. The unlikely event of an oil leak can be detected by a low Lube Oil Alarm annunciated in the Control Room, as well as the indications listed above. In addition, if the oil were to ignite, the following indications would give operators warning of the fire: RCP heat detection equipment, ambient air temperature monitors, and RCP motor stctor temperature alarms.

Finally, additional indication of a fire will be provided by installation of a heat detector in th2 cubicle in the area above the RCP motor. This detector will annunciate in the Control P,om.

7) Dry standpipes are located within containment. While the Unit is operating, fire hose is stored just outside the containment at the access hatch along with additional firefighting equipment. The equipment required to extinguish a fire by foam will also be stored near the containment access hatch. Foam will provide a rapid knockdown of an oil fire and is ef fective for an indirect attack (i.e.

applying the foam from the top of the cubicle and allowing it to flow down the walls and blanket the oil).

8) The cable routing in the containment assures that a fire in the "C" cubicle will not affect indications required for safe shutdown.

Loop "A" will provide indication to the Remote Monitoring Panel in the Service Building and loop "B" will provide indication to the Control Room via the Cable Vault Penetration for all safe shutdown parameters except L eam generator level. Loop "B" steam generator

3 1evel indication is available at the Remote Monitoring Panel in the Service Building.

Safe Shutdown Capability The primary safe shutdown equipment required for hot shutdown in the containment is instrumentation cabling. A fire. in the "C" RCP cubicle has the potential to disable all the "C" instrumentation. However, it would not af fect the redundant "A" instrumentation to the Service Building Remote Monitoring Panel nor the "B" instrumentation to the Cable Vault / Tunnel penetration leading to the Control Room for all safe shutdown parameters except steam generator level (available in the Service Building). Therefore, even with a total loss of the "C" instrumentation, redundant instrumentation indication will be available in the Control Room and at the Remote Monitoring Panel. Thus, a fire in the "C" cubicle would not adversely affect the ability to achieve safe shutdown.

Compensatory Measures Although our evaluation has determined that the Unit can be brought to a safe shutdown condition in the event of a lube oil fire in the "C" cubicle, there are several measures that we will take prior to restart of Unit 2 to provide additional assurance to detect or mitigate a lube oil leak / fire:

• Increased surveillance of temperature related parameters will be conducted. Increasing motor temperature indicates a possible oil leak.

• Existing heat detection instrumentation in the affected cubicle will be maintained. Additional heat detection instrumentation will be provided. This instrumentation will provide prompt detection in the event of a lube oil fire in the cubicle.

• Procedures will be revised to address operator actions in the event of an adverse trend. Such actions will include: immediate hatch or containment entry to identify reason for increasing temperatures, shutdown of affected pump, or response by fire brigade.

• Fire brigade members will be briefed on the potential for a fire in Unit 2 "C" cubicle and on the means to mitigate a fire in the area.

• Fire suppression equipment will be maintained outside containment j

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to be used by the fire brigade in the event of a lube oil fire. This includes placement of foam equipment at the containment access

! hatch.

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• Spray covers will be added above the floor penetrations in the concrete floor on the minus 3 ft. 6 in. elevation and a 4 inch lip will be added to the cubicle entranceway. As a result of these

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modifications the concrete floor will function as an oil reservoir to contain any oil which leaks into the cubicle.

• Shields will be installed as an additional protective measure to assist in keeping high pressure oil spray from directly impinging on hot reactor coolant piping.

CONCLUSION We believe that the operation of Surry Unit No. 2 using the interim RCP oil leak collection arrangement and associated compensatory measures in its upcoming cycle of operation is justified. We have demonstrated that the probability of a lube oil fire is low; that even in the event of a fire the plant can be brought to a safe shutdown condition; and, that we have taken additional measures to further mitigate the consequences of this event. We conclude that the interim oil leak collection arrangement and associated compensatory measures provide a comparable level of safety to that afforded by the normal leak collection system. Finally, we conclude that these measures meet the intent of Appendix R in that our ability to safely shutdown the plant in the event of a fire is not impaired.