ML20207M087

Responds to NRC Re Violations Noted in Insp Rept 50-362/88-20.Corrective Actions:Inadvertent Siphoning of Water from Spent Fuel Pool to Reactor Vessel Cavity Pool Halted Soon After Initiated

ML20207M087
Person / Time
Site:	San Onofre
Issue date:	10/14/1988
From:	Baskin K SOUTHERN CALIFORNIA EDISON CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
NUDOCS 8810180099
Download: ML20207M087 (4)

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U. S. Nuclear Regulatory Commission

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Attention: Document Control Desk l

Hashington, D. C.

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i Gentlemen:

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Subject:

Docket Number 50-362 Reply to a Notice of Violation i

San Onofre Nuclear Generating Station Unit 3

Reference:

Letter Mr. R. P. Zimmerman (NRC) to Mr. Kenneth P. Baskin i

l (SCE), dated September 15. 1988 The above referenced letter forwarded NRC Inspection Report Number i

i 50-362/88-20 and a Notice of Violation resulting from the routine inspection l

conducted by Hessrs. F. R. Huey, J. E. Tatum and A. L. Hon, during the period of July 3 through August 16, 1988.

In accordance with 10 CFR 2.201, the l

Enclosure to this letter provides the Southern California Edison (SCE) reply to the subject Notice of Violation.

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If you have any questiotis regarding SCE's response to the Notice of Violation t

or require additional information, please so advise, Respectfully submitted.

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1 Enclosure s

cc:

J. B. Hartin (Regional Administrator. NRC Region V) l F. R. Huey (NRC Senior Resident Inspector) f@\\

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$0R ADOCK 05000362 i

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PDC i

ENCLOSURE REPLY TO THE NOTICE OF VIOLATION Appendix A to Mr. Zimmerman's letter, dated September 15, 1988, states in part:

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"10 CFR Part 50, Appendix B Critorion V states, in part, that

' Activities affecting quality shall be prescribed by documented 3

instructions, procedures, or drawings, of a type appropriate to the I

circumstances and shall be accomplished in accordance with these instructions, procedures, or drawings.

"The SCE Topical Quality Assurance Manual, Chapter 5-A (Revision l

No. 7), Paragraph 12, states, in part, that ' Procedures shall be the l

basis for performance of actions... covered by the quality assurance program.'

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j "Paragraph 6.13 of Maintenance Procedure 50123-I-1.7 (TCN 2-2 dated l

May 6, 1988), titled Maintenance Order Preparation, Use and l

Scheduling, requires compliance with work packages and procedures, j

"Blanket Maintenance Order (MO) 87112010, in the Precautions section, directed the worker to ' Raise hoses or remove from pool to j

prevent siphoning when pump is secured.'

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"Contrary to the above requirements, a temporary pump installed to transfer water from the reactor vessel lower cavity to the spent fuel pool was started for an operational test on June 22, 1988, and i

4 the pump discharge hose was not raised or removed from the pool when the pump was secured. As a result, and (sic) inadvertent siphon path was established between the spent fuel pocl and the reactor t

vessel lower cavity.

t "This is a Severity Level IV violation (Supplement I) applicable to Unit 3."

RESEMSE

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REASON FOR THE VIOLATIM l

SCE admits that on June 22, 1988, personnel utilizing a temporary pump to transfer water from the reactor vessel lower cavity to the spent fuel pool (SFP) inadvertently established a siphon oetween the cavity and the SFP and i

left the siphon unattended.

This allowed water to be drawn from the SFP to l

1 the reactor vessel lower cavity.

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On June 22, 1988, personnel were attempting to reduce the reactor vessel lower i

cavity water level to approximately one foot below the reactor vessel flange by transferring water to the SFP, A lower water level was required to support i

ongoi" wk on a shutdown cooling isolation valve, which was disassembled.

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Horkers placed a submersible pump in the spent fuel transfer pool (which communicated directly with the reactor vessel lower cavity) and the discharge hose was placed in the neighboring SFP. The pump was started to verify operation; however, since control room operators were not prepared to support the water transfer evolution at that time, the individual in charge secured the pump and left the pump site without removing or raising the hose or otherwise verifying that a siphon had not been established, contrary to the maintenance order in effect for this task.

Since the pump and discharge line had been primed, a siphon was established, permitting water to flow from the SFP to the spent fuel transfer pool which in turn raised the level of the reactor vessel lower cavity. Hater overflowed from the lower cavity into the open reactor vessel and out the disassembled valve. Maintenance personnel working on the valve immediately notified the containment work manager, who directed that the temporary pump in the spent fuel transfer pool be started.

The reactor vessel lower cavity water level was quickly reduced, halting the spillage of water into the reactor vessel.

This water transfer was governed by a maintenance order which explicitly cautioned workers that they should be alert for and preclude siphon conditions by raising or removing the hoses or continuously monitoring the temporary water transfer system. The individual that performed the water transfer evolution failed to follow established requirements by performing the task without this maintenance order, instead assuming that he was familiar with the water transfer evolution and its precautions.

It should be noted that the end of the water hose in the SFP was two feet below the surface of the water.

If the siphon had continued undetected, at most, the water level of the SFP would have only been reduced by two feet during the siphon. A two foot drop in the spent fuel pool level would not have caused the Technical Specification minimum water level to have been violated.

CORRECIIVE ACTIONS THAT HAVE BEEN TAKEN AND RESULTS ACHIEED As discussed above, the inadvertent siphoning of water from the SFP to the reactor vessel cavity pool was halted soon after it was initiated. All Maintenance personnel have been instructed on the requirements to understand and comply with established programs and procedures governing the performance of maintenance work.

CORRECTIVE ACTIONS THAT HILL BE TAKEN TO AVOID FURTHER_V10LALLQNS All personnel that perform water transfer evolutions will be instructed on this event.

To ensure that all Maintenance refueling personnel that participate in water transfer evolutions fully understand the precautions specific to water transfers, these personnel will be required to participate in additional training on water transfers. Additionally, all future water transfers wil' be controlled by procedures (5023-I-3.1 and 501-I-3.25), and

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_3 implemented by a maintenance order.

These procedures will incorporate precautions currently in maintenance orders and will more explicitly require that siphon conditions be avoided by requiring that workers physically interrupt possible siphon paths prior to securing and leaving a submersible pump.

DATE HHEN F.ULL COMPLIANCE HILL BE AClilIYED Full compliance was achieved on June 22, 1988, when the siphon was halted.

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