05000346/LER-1979-057, To LER 79-057/01T-1:on 790518,determined Some Hydraulic Snubbers May Not Have Fulfilled Functional Requirements.Caused by Improper Installation & Restrictive Performance Limits

To LER 79-057/01T-1:on 790518,determined Some Hydraulic Snubbers May Not Have Fulfilled Functional Requirements.Caused by Improper Installation & Restrictive Performance Limits

ML19296D187
Person / Time
Site:	Davis Besse
Issue date:	05/30/1979
From:	Oneill J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19296D185	List: 05000346/LER-1979-057, To LER 79-057/01T-1:on 790518,determined Some Hydraulic Snubbers May Not Have Fulfilled Functional Requirements.Caused by Improper Installation & Restrictive Performance Limits
References
LER-79-057-01T, LER-79-57-1T, NUDOCS 8002290457
Download: ML19296D187 (3)

LER-1979-057, To LER 79-057/01T-1:on 790518,determined Some Hydraulic Snubbers May Not Have Fulfilled Functional Requirements.Caused by Improper Installation & Restrictive Performance Limits

Event date:
Report date:
3461979057R00 - NRC Website

text

U. S. NUCLE AR REGUL ATORY COMMISSION NRC r0RM 366 (7 71)

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EVENT DESCRIPTION AND PROBADLE CONSEQUE*JCES h LI_t was determined a reportable event existed in that some hydraulic snubbers may not l

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i lo j l The cause of this occurrence has been determif.ed to be due in part to both improper initial installation and self-imposed performance limits uhich were too restrictive.

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,j q l All safety related snubbers of less than 50,000 pounds capacity have 29, 1979.

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR P0h'ER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-79-07 DATE OF EVENT: May 18, 1979 FACILITY:

Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Hydraulic snubbers deficiency Conditions Prior to Occurrence: The unit was in Mode 5, with Power (ETT) = 0, and Load (Gross $$'C) = 0.

Description of Occurrence: At 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br /> on May 18, 1979, it was determined a repor-table event existed in that some hydraulic snubbers may not have fulfilled their functional requirements.

Plant snubbers, nuclear safety related with a capacity of less than 50.000 pounds, were in the process of being tested per Surveillance Test ST 5044.01, " Inspection of Safety Related Snubbers", which removes each snubber from its field location and tests the snubber on a test stand.

1l The following is a list of some of the deficiencies which existed:

(A)

Some snubbers had fittings installed which may not have provided seal, and may have permitted air in-leakage to degrada snubber performance.

(B)

Fluid reservoirs were installed on some snubbers with orientations which may not have allowed the reservoir to perform properly and/or allowed air in-leakage.

(C)

Installation of brackets mounting the local reservoirs for three snubbers were not per design and required removal of cap head body bolts which could have allowed air into the hydraulic cylinders and possibly disturbed the o-ring seals.

(D) Two snubbers had non-ethylene-propylene gasket material.

(E) Failure to meet lockup and biced rate requirements 1

A total of 288 snubbers were removed and functionally tested.

Of these, 152 did not meet all of the acceptance criteria.

This report is being submitted in accordance with Technical Specification 6.9.1.8.f.

Designa tion of Apparent Cause of Occurrence: The snubbers not meeting their accep-tance criteria has been attributed to the following causes:

1.

Improper handling, installation, and modifications made to snubbers 1

during plant construction 2.

Self-imposed performance limits which were too restrictive LER #79-057

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE PAGE 2 SUPPLEMENTAL INFORMATION FOR LER NP-32-79-07 Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. No seismic event was experienced during the period.

Corrective Action

Under R11ntenance Work order 79-2009, and as per Surveillance Test ST 5044.01, safety related snubbers with capacity of less than 50,000 pounds have been tested and deficient snubbers returned to original specifications.

During the time period between May 12, 1979 and June 29, 1979, 288 snubbers were removed and functionally tested.

Of these, 152 failed and were rebuilt by ITT Grinnell at their Warren, Ohio facility, by Wyle Engineering Laboratories, or onsite.

1 When the snubbers were returned, they were tested onsite and reinstalled.

Surveil-lance Test ST 5044.01 was performed on the snubbers and a separate inspection com-pleted by Toledo Edison Quality Control personnel. All non-conformances from these inspections were cleared, and all snubbers were operable on June 29, 1979.

Engineering is re-evaluating the acceptance criteria for snubbers to establish realistic perf ormance limits.

Failure Data: There have been no previously reported similar occurrences.

LER #79-057