ML19262A256

Abnormal Occurrence 50-289/74-25:on 741127,partial Loss of Fluid Found in Hydraulic Shock Absorbers.Caused by Minor Leaks in Snubber Fittings & Reservoir End Caps.Reservoirs Refilled,Leaks Repaired & Addl Insp Procedures Initiated

ML19262A256
Person / Time
Site:	Three Mile Island
Issue date:	12/06/1974
From:	Arnold R METROPOLITAN EDISON CO.
To:
References
NUDOCS 7910260591
Download: ML19262A256 (5)

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DATEC.:COC OATE R EC'O LTR T'.'! X ' R P T CT-ER FRO.'.': Metropolitan Edisen Co.

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CCC 1 50-289 DESCR:?Ti ^: Ltr reporting Abnormal occurrence ENCLCEURES:

A0-50-289/74-25on11-27-74 involving partis L loss of finid in some hydraulic shock absort 3rs.....

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Directorate of Licensing .. . If U. S. Atomic Energy Commission -

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Dear Sir:

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Operating License DPR-50 Docket No. 50-289 The following is a report of a situation which was originally considered to represent an abnormal occurrence but which, upon review, has been determined to not represent an abnormal occurrence as defined by the Technical Specifications for our Three Mile Island Nuclear Station, Unit 1 (see the discussion under Item 8 below) :

(1) Report Number: A0 50-289/74-25 (2a) Report Date: December 5,1974 (2b) Occurrence Date: November 27, 1974 (3) Facility: Three Ilile Island Nuclear Station, Unit 1 (4) Identification of Occurrence:

Title: Partial Loss of Fluid in some Hydraulic Shock Absorbers Type: See opening statement.

(5) Conditions Prior to Occurrence: The Reactor Coolant System was in a cold shutdown condition, with major plant parameters as follows:

Power: Core: 2535 FM (Gross)

Elec: 870 FM 6

RC Flow: 140 x 10 lbs/hr RC Pressure: 2155 psig 1248C 1484 254

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Directorate of Licensing DEC6 1974

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RC Temp.: 579 F PRZR Level: 240 in PR2R Temp.: 550 F (6) Descrip tion of Occurrence:

During a routine walk-through inspection of the latermediate Building, five hydraulic shock suppressors (snubbers) located on the Main Steam (MS) lines were found to have unusually low levels of hydraulic fluid in their reservoirs due to ninor leaks on some of the snubber fittings and reservoir end caps. The following is a list of these snubbers and their locations:

Number Location MS 224 MS Isolation Valve A; 354 ' Level of the Inter-mediate Building.

MS 226 MS Isolation Valve C ; 354 ' Level of the Inter-mediate Building.

MS 220 MS Isolation Valve D; 354 ' Level of the Inter-mediate Building.

MS 227 MS Isolation Valve D ; 354 ' Level of the Inter-mediate Building.

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MS 216 MS Line D before MS Isolation Valve D; 345 ' Level of the Intermediate Building.

It should be noted that the November 27, 1974, telephone and telegram reports to the DORO-Region 1 office referred to enly four snubbers with low fluid levels . The fifth snubber mentioned above was identi-fled shortly af ter these two reports had been made.

(7) Designation of Apparent Cause of Occurrence:

Material failure was the apparent cause of the occurrence in that the minor leaks which developed in some of the snubber fittings and reservoir end caps allowed hydraulic fluid to drain from the reservoirs of the snubbers.

(8) Analysis of Occurrence:

It has been determined that the lower-than-usual levels of hydraulic fluid in the reservoirs of the subject snubbers did not constitute an abnormal occurrence and did not , therefore , constitute a threat to either the health or safety of the public. The reasons for having made this determination are:

1484 255

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Directorate of Lic s , DEC6 1974

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- 1. there was still some fluid remair.ing in all of the snubber reservoirs ; with fluid remaining in the reservoirs it can be con-cluded that the snubber valve assemblies were filled with hydraulic fluid ; and with fluid in the valve assemblies , the valves will

" lock-up" under a design seismic event and thus perform their intended safety function, and

2. this situation did not threaten to reader the subject snubbers inoperable in that routine periodic inspections of these assemblies would have prevented them f rom becomlag drained of hydraulic fluid.

(9) Corrective Action:

As an immediate corrective action, the reservoirs of the subject snubbers were refilled and all detectable leaks were repaired. As an additional short-term action, all the other snubbers in the inter-mediate Building were inspected. No other problems were identified.

At a meeting held soon after this occurrence was reported, the Plant Operations Review Committee reviewed and gave its approval of these actions and recommended to the Station Superintendent that the following long-term actions be taken:

a. Reinspect the five subject snubbers at frequent intervals until all sources of leakage have been identified nd eliminated.

b. Continue the periodic inspection of all snubbers on safety-related systems as required by the Technical Specifications .

c. Continue the recently cot.menced snubber seal replacement program (see the letter from R. C. Arnold to A. Giambusso, dated February 14, 1974).

The Station Superintendent concurred with these recommendations and has taken the necessary steps to insure their implementation.

(10) Failure Data:

Previous Failurea:

See Abnormal Occurrence Reports A0 50-289/74-14, 74-20, and 74-23.

Equipment Identification:

Snubber Assembly Brand--Grinnell Cylinder Type--Lyna Valve Type--Grinnell Bore--2.5 in Stroke--S in Sincerely, n1 R. C . old Vice President RCA :JFV :sh 1484 256

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_ Directorate of Licensing .

cc: Directorate of Regulatory Operations , Region 1 U. S. Atomic Energy Commission 631 Park Avenue King of Prussia, Pennsylvania 19406 File: 20.1.1 7.7.3.5.1 1484 257