ML19262A261

Abnormal Occurrence 50-289/74-23:on 741120,misorientation of Several Shock Suppressors & Loss of Hydraulic Fluid Noted. Caused by Incomplete Procedure,Seal Deterioration & Improper Mfg of End Caps.Snubbers Returned to Svc

ML19262A261
Person / Time
Site:	Three Mile Island
Issue date:	11/30/1974
From:	Arnold R METROPOLITAN EDISON CO.
To:
References
NUDOCS 7910260596
Download: ML19262A261 (5)

Text

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F ROT.1: Metropolitan Edison Co. DATE OF DOC DATE REC'O LTR TV!X RPT OTHER Reading, Pa. 19603 i ns7A y Mr. R.C. Arnold 11-30-74 CC OTHER ~~SENT AEC POR XXX TO: ORIG AEC 1 signed SENT LOCAL POR M

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M 1 50-289 DESCRIPTION: ENCLOSURES:

Ler reporting an abnormal occurrence at the .

Three Mile Island #1 facility...A0 50-289/74-

23. . . . concern. . . . Loss of Hydraulic Fluid from ,ACKLT('pTT a -'-"' O.~~'~) --

and Misorientation of Several Shock Suppressors

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Regulatory Docket File g ~

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Directorate of Licensing ' - ' -

U.E Atomic Energy Commission W shington, D. C. 20545

Dear Sir:

Operating License DPR-50 Docket No . 50-289 In r- -ace with the Technical Specifications for Three Mile n-Nuc. >r renc'>

_ation, Unit 1, we are reporting the following abno a

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(1) Report Number: A0 50-289/74-23 DEC 5 1974 2

(2a) Report Date : November 29, 1974 [S$f;(

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(2b) Occurrence Date: November 20, 1974 A

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(3) Facility: Three Mile Island Nuclear Generating Station, Unit (4) Identification of Occurrence:

Ti tle : Loss of Hydraulic Fluid from and Misorientation of Several Shock Suppressors.

Type: An abnormal occurrence as defined by the Technical Speci-fications , paragraph 1.8d , in that the loss of hydraulic fluid from and misorientation of several shock suppressors threatened to cause an Engineered Safeguards feature or system to be incapable of performing its intended function.

(5) Conditions Prior to Occurrence:

Hot shutdown with major plant parameters as follows :

Power: Core: 0 FMT Elec : 0 >ME 1210t

RO Ficv: lho x 106 133,/37, RC Pressure: 2265 psig RC Temp.. 532 F FRCR Level: 200 in.

FRZR Temp. 655 F (6) Description of Occurrence:

During a routine inspecticn of the Reactor Building en November 20, 197h, Hydraulic Shock Suppressor (Snubber) MS-209 was fcund to be out of position (upside devn) and drained of fluid. This snubber is located en the D Main Steam (MS) Line frcm the 3 Once-Through Steam Generator (OTSG) at the 338' Level of the Reactor Building.

A further inspection of snubbers in the Reactor Building revealed that there were problems involving additional snubbers as follows :

FG 210 MS Line D from 3 OTSG; 333' Level - Apparent detericration of the snubber seal and partial loss of fluid.

SS 20h MS Line 3 from A GTSG; 329' Level - During a maintenance outage inspection on August 31, 197h, snubber was found to be upside down.

The reservoir was refilled but the snubber was not reoriented at that time.

MS 283 MS Line D from 3 OTSG; 329' Level - Reservoir endcaps improperly tightened and partial less of fluid.

Serial # 25.lh620.003, lA Reactor Coolant Pump - Fittings improperly tightened and partial loss of fluid.

(7) Designation of Apparent Cause of Occurrence:

An inccmplete precedure was the apparent cause of the cecurrence involving Snubber MS 209, in that the procedure which was used during the installation did not specify the use of Lectite, or similar substance, which woud have prevented the snubber from rotating out of position. An incc=plete crocedure was also the apparent cause of the situation involving Snubber MS 20h in that the procedure used for repair of the snubter did not specifically state that the cylinder was to be reoriented.

The loss of fluid free MS 210 was apparently caused by deterioration of the seal and was, therefore, caused by a material failure.

The loss of fluid frcm MS 268 is considered to be due to improper nanufacture in that the reservcir end caps were not properly tightened at the factory.

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Improper installation during construction is bel ved to have caused the partial loss of fluid from the Snubber with serial number 25.14620.003 in that fittings were not, properly, tightened 4pring construction.

(8) Analysis of Occurrence:

(a) As snubbers MS 210, MS 288, and 25.14620.003 all contained fluid when examined, they would have performed their intended functions in the event of a seismic occurrence.

(b) The worst possible consequence of a loss of fluid from MS 2N-and >$ 204 would take place during a seismic occurrence when the Main Steam Line would start to vibrate . Under such conditions, tha Main Steam Line could break if the shock suppressors were ineffective; however, because the Main Steam Line has been very conservatively designed, a broken line is considered unlikely under any circumstances.

(9) Corrective Action:

The following short-term corrective actions were taken by plant personnel to return the affected snubbers to service:

MS 209 - The snubber was reoriented, the locknut tightened using Loctite, and the fluid replaced.

MS 210 - The snubber was replaced; the new cylinder has ethylene-propylene seals .

MS 204 - The snubber was reoriented and the locknut tightened using Loctite.

MS 288 - The reservoir end caps were tightened and the reservoir was refilled.

25.14620.003 - All fittings were tightened and the reservoir was refilled.

In a meeting held af ter the incident was reported the Plant Operations Review Committee (PORC) reviewed and approved the above actions and recommended to the Station Superintendent that the following long-term corrective actions be taken:

(a) A program will be instituted to inspect all snubbers in the Unit 1 Reactor Building at approximately 120-day intervals .

(b) The inspection ard seal replace =ent program (see letter from R. C . Arnold to n. Giambusso dated February 14,1974) will be reviewed , amet ded as necessary, and any revisions will be implemented as so in as possible.

(c) As a portion of t 2e normal operator training program, an added lecture will be given to each operating section on snubber design and operation with emphasis en routine inspection of hydraulic snubbers.

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4 e The Station Superintendent concurred with PORC 's findings and has taken steps to ensure completion of the long-term correcti're actions listed above, and has also taken steps to ensure that the procedure used for repair of snubbers will be revised to require personnel to reorient them.

(10) Failure Data:

(a) Previous Failures:

See Abnormal Occurrence Rcports A0 50-28/74-14,. dated August 28, 1974, and A0 50-289/74-20, dated November 8,1974.

(b) Equipment Identification:

MS 209 MS 210 MS 204 MS 288 25.14620.003 Snubber Assembly Brand Grinnel Grinnel Grinnel Grinnel McDowell-Wellman Cylinder Type Lindco Lindco Lindco Lindco McDowell-Wellaan Valve Type Grinnel Grinnel Grinnel Grinnel McDowell-Wellman Size 4" 2h" 2h" 2h" 7" Stroke 5" 5" 5" 5" 5" Sincerely R. h Vice President RCA/cas File: 20.1.1/7.7.3.5.1 cc: Directorate of Regulatory Operation's, Region 1 U.S. Atomic Energy Commission 631 Park Avenue King of Prussia, PA 19406 1484 273