ML19351A414

LER 89-020-00:on 890915,discovered That RHR Pump Motors & Core Spray Pump Motors Had Nonconforming Boot Installation Configuration.Caused by Less than Adequate or Incomplete Procedures.Splice Configurations restored.W/891016 Ltr

ML19351A414
Person / Time
Site:	Peach Bottom
Issue date:	10/16/1989
From:	Cribbe T, Danni Smith PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-020-02, LER-89-20-2, NUDOCS 8910230133
Download: ML19351A414 (5)

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PHILADELPHIA ELECTRIC COMPANY i~ PEACII bOTIUM A10MIC POWLR STATION R. D.1, Ikix 208 Iktta, linnsybunia 17314 ',

ruas sorrtw-tm cosim or xcnence - (717)456-7014 D. M. Smith i Vice President L:

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october 16, 1989 Docket No. 50-277 ,

t Document. Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555 /

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SUBJECT:

Licensee Event Report Peach Bottom Atomic Power Station - Unit 2 This LER concerns a 4 KV motor lead to field cable splice insulation configuration which did not meet environmental qualifications.

Reference:

Docket No. 50-277 Report Number: 2-89-020 Revision Number: 00 1 Event Date: 09/15/89 Report Date: 10/16/89 Facility: Peach Bottom Atomic Power Station RD 1, Box 208A, Delta PA 17314 ,

! This LER is being submitted pursuant to the requirements of 10 CFR L-- 50.73(a)(2)(1)(C),10CFR50.73(a)(2)(ii)(B),and10CFR50.73(a)(2)(v).

l l Sincerely, cc: T. P. Johnson, USNRC Senior Resident Inspector W. T. Russell, USNRC, Region I JELL 1

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I F ACILITV NAME til DOCEET NUMetR (2e PAGE G Peach Bottom Atomic Power Station - Unit 2 ol5lol0[o]2l7l7 1l0Fl0l4 v TITL4 der Environmental Qualification Non-compliance Resulting in Inoperable Residual Heat Removal Pumn Motora Due to Incomulqte Procedurp1 Guidance Durinn Initial Installation 1 avtNT DATE 46) - LER NvMetR tel REPORT DAf f 17) OTHER F ActLITits tN#0LVED ISI j MoNTw DAv vtAR vtAR 5 'C ',,' ' Tf,W MONTH DAY v t Ast '^c'utva'*** DOCMT Nuwstnisi PBAPS - Unit 3 o is to lo g o t 2l7 l8 j l

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l On September 15, 1989 an evaluation of a non-conforming Environmental Qualification .l (EQ) condition associated with the 4 Kilovolt (KV) motor lead to field cable splice l l- insulation method was completed. The as found configuration consisted of a molded i

' insulating boot held in place by either electrical tape or cable tie wraps. An l

) ' inspection was initiated to determine the scope of the non-conformance with respect  ;

l to other 4 KV EQ motors (RHR and Core Spray pump motors). Three Unit 3 RHR pump l motors, four Unit 3 Core Spray pump motors, one Unit 2 RHR pump motor, and one Unit 2 Core Spray pump motor had the non-conforming boot insulation configuration. The non-conforming splice configurations were restored to the correct configurations. The root cause of this event was a less than adequate or incomplete procedure (s) used during initial plant construction, and each subsequent de-termination /re-termination of the RHR pump motors. Appropriate maintenance procedures associated with 4 KV motors will be reviewed and revised as necessary to include the details for re-l termination of the motor leads. There were no previous similar events.

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0 l0 0l2 oF 0p Requirements for the Report j This report is required per 10CFR50.73(a)(2)(1)(C). 10CFR50.73(a)(2)(ii)(B), and 10CFR50.73(a)(2)(v) because safety related electrical equipment's motor lead (EIIS:JX) to field cable splice (EIIS:CSL5) insulation (EIIS:ISL) configuration did not meet environmental qualification (EQ) requirements.

Unit Status at Time of the Event Unit 2 was in the Run Mode at 100% of Rated Thermal Power.

" Unit 3 was shutdown with the Reactor Mode Switch (EIIS:HS) in Shutdown.

There-were no structures, components, or systems, that were inoperable at the start  !

of the event that contributed to the event. I Description of the Event On August 24, 1989 during an inspection of the 3C Residual Heat Removal (RHR) l (EIIS:B0) pump (EIIS:P) motor (EIIS:M0) by an EQ Coordinator a non-conformance  !

condition was identified. The non-conformance was associated with the as found RHR pump motor lead to field cable splice insulation configuration, which consisted of a molded insulating boot held in place by either electrical tape or nylon cable tie wraps. This configuration was not installed as detailed in design document E-1317 and therefore had not been evaluated for environmental qualification requirements. A review to support environmental qualification was requested. '

An inspection was initiated to determine the scope of the non-conformance with  ;

respect to other 4 Kilovolt (KV) EQ motors (RHR and Core Spray (EIIS:BM) pump  ;

motors). It was determined that Unit 3 B, C, and 0 RHR pump motors, and the four Unit 3 Core Spray pump motors had the boot insulating configuration. RHR pump motor i 3A was recently replaced with a RHR pump motor obtained from the Skagit Nuclear Power Plant. On Unit 2 the 2A RHR pump motor and 2C Core Spray pump motor had the unacceptable boot insulating configuration.

During the inspection process, if it was found the boot insulation configuration was j used, then the non-conforming splice configurations were restored to the correct '

configuration. By September 8, 1989 the three Unit 3 RHR pump motors had been restored to the correct configuration. By September 17, 1989 the four Unit 3 Core Spray pump motors were restored to the correct configuration. The 2A RHR pump motor was re-worked on September 15, 1989, and the 2C Core Spray pump motor was restored to the correct configuration on September 21, 1959.

j On September 15, 1989 Philadelphia Electric Company (PECo) completed its EQ i evaluation of the as found non-conformance. It was determined the boot insuiation l' configuration is acceptable for non EQ installations. Based on Laborator.y analysis and using Engineering judgement, the Core Spray pump motors were capable of being qualified to EQ requirements. The RHR pump motors were originally found to be indeterminate because tne boot securing method and radiation tolerance was unki:own.

The limiting environmental condition was determined to be integrated radiation dose.

A damage threshold of 4.5E6 radiation absorbed dose (rads) integrated dose was Nxc sozu seeA *v.s. cros t ese-s zo- sav, cook i -*

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010 0 l3 0 l4 itKT C mene spece h reewed, une onweanet NRC farm NSA M (1h conservatively established as the EQ limit for the molded boot configuration. Based l

- on the post Loss Of Coolant Accident (LOCA) Environmental profiles for the Core Spray  !

pump rooms, the Core Spray pump splices were capable of being qualified to EQ requirements. However, as a result of the Environmental profile in the RHR pump rooms the RHR pump slices were determined not to meet EQ requirements.

Cause of the Event c The root cause of this event was a less than adequate or incomplete procedure (s) used l during initial plant construction, and each subsequent de-termination /re-termination (

of the RHR pump motor.

During Unit 2 construction (prior to August 1973), the RHR and Core Spray pump motor {

installations were done in accordance with E-1317. This type of splice was  !

subsequently qualified as part of the environmental qualification program. i During Unit 3 construction (prior to July 1974, and prior to EQ requirements), the boot insulation configuration was used as an alternative to the tape configuration l although the tape method was shown in E-1317. Engineering approvals of alternate insulation methods were not documented in specification E-1317. These boots are useo  ;

elsewhere in the PECo System and were readily available to the craftsmen. J Site Maintenance procedures did not specify the termination detail, therefore practice has been to reinstall the terminations to their "as-found" condition.

It was determined that the Unit 2A RHR pump motor, which had the unqualified boot  !

insulating configuration, occurred as a result of relocating the Unit 3A RHR pump motor. The boot was taken with the Unit 3 RHR pump motor and installed in the Unit 2 RHR system. This condition has existed since April 1989. j Documentation could not be found identifying how or when the 2C Core Spray pump motor i obtained its boot insulation configuration. The Core Spray pumps were subsequently determined to be qualified with this configuration. The RHR and Core Spray pump motors are the only locations where the unqualified boot insulation configuration l

could have been used on EQ 1arge motors.

Analysis of the Event j' No safety consequences occurred as a result of this event.

l' l The boot insulation configuration is acceptable in environments that occur during l-normal operation and anticipated transients. Environmental qualification of electrical equipment is necessary for certain safety related equipment exposed to post accident environment which has a significant increase in temperature, pressure, humidity and/or radiation levels.

Assuming core (EIIS:AC) damage does not occur the radiation levels within the RHR I rooms are acceptable to environmentally qualify the boot splice method of insulation.

) Using Probabilistic Risk Assessment (PRA) methodology developed for PBAPS in l accordance with NUREG CR 4550 Volume 4, the probability of an accident occurring l which would result in core damage is 4.6E(-6) events per reactor year. The PRA also

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0 l0 0 l4 oF 0l4 inxi ta m m e m me =am=w Nnc m anu v (m states that from accidents postulated which could lead to core damage, the LOCA is only 6% of the risk.

The limiting condition in the event of a core damaging LOCA would be the higher-integrated radiation dose in the RHR rooms. Based on these higher radiation levels the nylon cable tie wraps or electrical tape holding the boot may deteriorate allowing movement of the insulating material. An electrical fault may have then resulted in an inoperable pump. The loss of one RHR pump would not prevent the

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Emergency Core Cooling Systems from mitigating the consequences of a design basis LOCA because four pumps are installed, each rated at 33 1/3% capacity.

In the unlikely event that the four RHR pumps would have become inoperable during a core damaging LOCA event, the redundant Core Spray pumps would be able to maintain reactor water level. Containment Cooling would then become the limiting factor.

Emergency' Procedure Guidelines exist to maintain long term containment cooling without the RHR pumps and still maintain reactor containment (EIIS:NH) integrity.

Corrective Actions The non-conforming splice configurations were restored to the correct configuration.

Appropriate maintenance procedures associated with safety related motors will be reviewed, revised or developed as necessary to include the details for the re-termination of the motor leads.

Previous Similar Events No previous similar LERs were identified resulting from improper termination of 7

electrical leads to 4 KV motors.

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