05000245/LER-1982-020, Forwards Updated LER 82-020/01X-2.Detailed Event Analysis Encl

Forwards Updated LER 82-020/01X-2.Detailed Event Analysis Encl

ML20028C858
Person / Time
Site:	Millstone
Issue date:	01/05/1983
From:	Mroczka E NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20028C859	List: 05000245/LER-1982-020, Forwards Updated LER 82-020/01X-2.Detailed Event Analysis Encl 05000245/LER-1982-020-01, During Hydraulic Snubber Functional Test,Four Itt Grinnell Snubbers Failed to Meet Design Acceptance Ranges.Caused by Oil Leakage Through Cracked Reservoir Glass.Snubbers Repaired
References
MP-4560, TAC-55011, NUDOCS 8301140237
Download: ML20028C858 (3)

LER-1982-020, Forwards Updated LER 82-020/01X-2.Detailed Event Analysis Encl

Event date:
Report date:
2451982020R00 - NRC Website

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'= ";3'LT""I' January 5,1983 MP-4560 Mr. Ronald C. Haynes Regional Administrator, Region I Office of Inspection and thforcement U. S. Nuclear Regulatory Ca mission 631 Park Avenue King of Pnissia, Pennsylvania 19406

Reference:

Provisional License DPR-21 Docket No. 50-245 Reportable Occurrence RO-82-20/lX-2 (Update Report)

Dear Mr. Haynes:

This letter forwards the Licensee Event Report for Reportable Occurrence RO-82-20/1T-1. 'Ihis update report provides additional information on the two snubber failures discovered during the 1982 refuel outage. An additional three copies of the reports are enclosed.

Yours truly, NORI1 EAST NIX' LEAR DERGY C04PANY

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E. J. Mroczka h Station Superintendent Millstone Nuclear Power Station FJM/TST:no

Attachment:

LER RO-82-20/1X-2 cc: Director, Office of Inspection and Enforcament, Washington, D. C.

(30)

Director, Office of Management Information and Program Control, Washington, D. C.

(3)

U. S. Nuclear Regulatory Camission, c/o Document Managment Branch, Washington, D. C. 20555 i

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8301140237 830105 PDR ADOCK 05000245 S

PDR

g Attacnmtat to LER 82-20/1X-2 Northeast Nuclear Energy Ccmpany -

. Millstone Nuclear Ibwer Station - Unit 1 Provisional License Ntmiber DPR Docket Ntmiber 50-245 IDENTIFICATICN N. 00CURRENCE Performance of ccmponents that required corrective action to prevent operation in a manner less conservative than established in Technical Specifications were discovered when hydraulic snubbers failed to meet their surveillance requiremento.

CWDITINS PRIOR TO 00CURRENCE Prior to occurrence the unit was shutdown for a refueling outage.

DEPi'RIPTIN OF 00CURRENCE On September 30,1982, at 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br />,while performing a Hydraulic Snubber Functional test in accordance with Technical Specification 4.6.I.3, on a sanple of 10 snubbers, four ITT Grinnell snubbers failed to fall within their rectmmended ranges. Of the four, one failed lock up and bleed rate require-ments and three failed the bleed rate requirements. Further detailed eval-uations on the four failures revealed that three did meet their specific design acceptance ranges and one snubber failed to meet the specific design acceptance range. As required by Technical Specifications, an additional sanple of 10 snubbers were functionally tested. All were found acceptable.

The visual examination of all snubbers performed in accordance with Technical Specification 4.6.I.1 indicated three possible failures based on the reservoir oil level. Functional testing on these three snubbers in the as found condi-tion revealed only one snubber failure. 'Ihis changes the required visual inspection interval frcm 18 months to 12 months plus or minus 25 percent.

APPARENT CAUSE OF OCCURRENCE Investigation into the cause of the snubber that failed to meet lock up and bleed rate requirements revealed a lack of hydraulic fluid in its reservoir due to an inproper fit of the fluid reservoir cylinder. 'Ihe single confirmed visual examinstion failure was contributed to oil leakage through the cracked reservoir glass.

ANALYSIS OF 00CURRENCE A review of the hanger configuration indicated that with the two snubber failures, the remaining snubbers were capable of restraining the affected pipes during a seismic event.

Both of the snubbers in question are installed on their respective pipes in a single plane, parallel to either side of the pipes. '1his design allows a pair of snubbers to each accept one half the pipe load.

If one snubber fails to lock up, the second operable snubber would be subjected to the full pipe load.

In both cases the snubber installed in parallel to each of the failures was i

available and would have carried the full pipe load. '1herefore, the integrity of the affected piping systes was not reduced.

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M ACTIW

'the two ITT Grinnell snu2ers which failed to meet their surveillance criteria were repaired, tested for functional acceptability ard placed back in' service.

In the future the re>_--Med acceptable ranges for functional' testing of hydraulic snubbers will be evaluated on an individual basis for each safety related snubber as ocmpared to the present rv -- Med acceptable ranges which were-done on a group basis.

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