ML19210A149

Event Rept 76-07/1T:on 760211,inoperative Hydraulic Shock Suppressor Threatened Performance of Engineered Safety Feature.Apparent Cause:Matl Damage Due to Low Fluid Level in Snubber.Snubber to Be Checked Periodically for Leakage

ML19210A149
Person / Time
Site:	Three Mile Island
Issue date:	02/21/1976
From:	Arnold R METROPOLITAN EDISON CO.
To:
Shared Package
ML19210A150	List: ML19210A149 ML19210A151
References
ER-76-07-01T, ER-76-7-1T, GQL-0263, GQL-263, NUDOCS 7910240874
Download: ML19210A149 (4)

Text

NRC PORu 135 -

u.S. NUCLEAR REGULATORY MISSs**! DOCKET NUM SC M 50-289 (2 He

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OCOPY DESCRIPTION ENCLOSURE LTR, LICENSE EVENT REPORT 50-289/76-07/1T ON 2-11-76 RE INOPERATIVE HYDRAULIC SHOCK SUPPRESSOR WAS DUE TO THE "A" HEAT PCMP SUCTION LINE WAS FOUND WITH AN EMPTY FLUID RESEVOIR. .

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POST OFFICE BOX 542 READING. PENNSYLVANI A 19G03 TELEPHONE 215 - 929-3601 DJ

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Dear Sir:

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Docket No. 50-289 Cperating License No. DPR-50 In accordance with the Technical Specifications of cur Three Mile Island Nuclear Station Unit 1 (TMI-1), we are reporting the folleving reportable occurrence.

(1) Report Number: ER 76-07/lT (2a) Report Date: February 21, 1976 (2b) Event Date: February 11, 1976 (3) Facility: Three Mile Island Nuclear Station Unit 1 (h) Identification of Event:

Title:

In6 perative Hydraulic Shock Suppressor Type: An abnormal occurrence as defined by the Technical Specificaticns, paragraph 1.8d, in that the inoperative hydraulic shock suppressor threatened to cause an Engineered Safeguards feature or system to be incapable of performing its intended functicn.

(5) Conditions Prior to INent: -

Power: Core: 1005 Elec.: 870 MWe (Grcss)

RC Flev: lho x 106 lbs/hr 1490 063 1768

s RC Pressure: 2155 psig RC Temp.: 5790F Przr level: 2h0 inches Przr Temp.: 650 F (6) Description of Event:

Cn February 11, 1976, during a reuti:.e surveillance of snubbers in the Auxiliary Building, one (1) snubber located at position EHH-198 en the "A" Decay Heat Pump Suction line was found with an empty fluid resevoir. L=nediately, the unit was removed and replaced with a rebuilt, tested unit.

The failed unit was tested and failed to lock as specified. It was then rebuilt, tested, and returned to service at 1ccation EHH-198.

(7) Designation of Apparent Cause of Event:

The attarent cause of this event has been determined to be material in that, althcugh the seals removed from the inoperable snubber did not reveal any damnge to the sealing surface, this unit has been found with lov, but acceptable, fluid levels en other occasions before and after its initial rebuilding in June 1975 at which time ethylene propylene seals were installed.

(8) Analysis of Event:

It has been determined that this event did not constitute a' threat to the health and safety of the public in that the conservatism of the piping design is such that one st ibber may be inoperable with a negligible loss of seismic protectic:. since other restraints and snubbers installed en the line vould provide the support necessary to prevent failure of the pipe.

(9) Corrective Action:

In addition to the i= mediate corrective action described above, the EHH-198 snubber vill continue to be checked in accordance with the present Snubber Surveillance Program and in additien, vill be checked periodically by the Mechanical Engineering section to monitor any further leakage.

The Plant Operations Review Cc=mittee and Statien Superintendent have reviewed and approved the above corrective acticn and have taken steps to ensure its implementation.

(10) Failure Data:

Snubber ITg. : Basic Engineers 064 Cylinder Type: Tompkins-Johnson Size: Cne (1) inch

Stroke: five (3) inches (11) Similar P. rents:

A0 50-289/Th -lk, AO 50-289/Th-20 A0 50-289/Th-23, A0 50-289/Th-25 A0 SG-289/Th-30, A0 50-289/T5-03 A0 50-289/Th-08, A0 50-289/75-09 A0 50-289/75-3h Sincerely, t.

R. C. *nold Vice President RCA:JMC:cas 1490 065