ML20207E145

Ro:On 860616,inoperability of All LPCI Sys Reported.Caused by Improper Torquing of Stud Nuts on All RHR Pump Sections & Discharge Flanges.Sys Operable Per Bechtel Spec 10855-P-202(Q)

ML20207E145
Person / Time
Site:	Hope Creek
Issue date:	07/21/1986
From:	Salvesen R Public Service Enterprise Group
To:	NRC OFFICE OF ADMINISTRATION (ADM)
References
NUDOCS 8607220273
Download: ML20207E145 (2)

Text

O PSEG Public Service Electnc and Gas Company P.O. Box L Hancocks Bndge. New Jersey 08038 Hope Creek Operations U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555

Dear Sir:

HOPE CREEK GENERATING STATION DOCKET NO. 50-354 UNIT NO. 1 CLARIFICATION OF FOUR-HOUR NON EMERGENCY EVENT REPORT OF 6/16/86 On June 16, 1986, the HCGS Senior Nuclear Shift Supervisor contacted the NRC Operations Center to report the inopecability of all Low Pressure Coolant Injection Systems.

The basis for the report was the discov.ery of apparently improper torquing of stud nuts on all RHR pump suction and discharge flanges. The notification was made pursuant to 10CFR50.72 (b) (2) (i) which requires a four hour report of any event " ...found while the reactor is shut down, that, had it been found while the reactor was in operation, would have resulted in the nuclear power plant, including its principal safety barriers, being seriously degraded...".

In investigating the occurrence plant engineers considered a number of different root causes. First, a review of work orders was initiated to determine if maintenance activities could have resulted in loose or improperly torqued bolts. No activities were identified. Second, pump vibration readings were reviewed to determine if excessive vibration had loosened the subject stud nuts. All RHR pump vibration levels were found to be within acceptable ranges. Finally, a review of the Architect Engineer (Bechtel) construction methods was undertaken. Plant engineers determined that the incident could be tracked to these techniques.

Bechtel Specification 10855-P-202(0) described the program for field fabrication and installation of piping for nuclear systems at Hope Creek Generating Station. This program covered systems rated at 600 psig or greater. For systems such as RHR with piping rated less than 600 psig, no specific torquing requirements were provided.

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To verify piping integrity on the RHR system prior to turnover from Bechtel to PSEEG, a hydrostatic test was performed in accordance with Bechtel Test Specification 19855-P-599(Q). Through established leakage criteria, the hydrostatic test verified system integrity which included acceptable flange bolting.

PSEEG has a well defined maintenance program which includes torquing all bolts, nuts and fasteners depending on fastener characteristics, gasket type, and strength requirements.

This program is used for all pressure piping systems not just 699 psig rated piping and greater.

In the subject incident, upon finding torque values below that specified in the plant maintenance procedures, operators were led to believe that there had been a breakdown in the construction program and thus questioned the operability of the subject systems. Based on this, the Senior Nuclear Shift Supervisor considered it prudent to make the four hour notification pursuant to 19CFR59.72(b) (2) (i) . In actuality, Bechtel had demonstrated the integrity of the piping systems for RHR in a different, yet acceptable manner. Although the Bechtel specifications did not preclude flange leaks, there was never a concern for catastrophic structural failure since the bolts were properly sized to match the flange rating.

Thus the systems were never, in fact, inoperable.

While the systems are considered operable, the plant system engineering group has outlined a torquing program for the low pressure ECC systems. The intent of the program is to verify that other flanges within the Core Spray and RHR systems are torqued to the requirements of PSE&G program.

Since the Low Pressure Coolant Injection Systems were never in fact, inoperable, the event does not meet the criteria of 10CFR59.72 (b) (2) (i) and thus the report made by the operating shift is considered a conservative measure taken based upon the information available at the time. Similarly, a Licensee Event Report will not be submitted for this event as it does

. not meet the criteria provided in 19CFR59.73 (a) (2) (ii) .

However, due to the nature of the event, PSE&G considered a detailed account of the occurrence appropriate.

4 Sincerely, e

R. S. Salvesen General Manager l Hope Creek Operations WJM:bar i SORC Meeting 86-163

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