ML19261F297

Abnormal Occurrence 50-289/74-14:on 740818,during Insp of Hydraulic Shock Suppresors,Three Reservoirs Found Empty of Hydraulic Fluid.Caused by Improper Installation & Possible Component Failure.Suppressors Refilled & Replaced

ML19261F297
Person / Time
Site:	Three Mile Island
Issue date:	08/28/1974
From:	Arnold R METROPOLITAN EDISON CO.
To:
References
GQL-0280, GQL-280, NUDOCS 7910250753
Download: ML19261F297 (5)

Text

.EC D!mIEL-~C'! FOR W"' 5 0 CCET MA ERI AL a (TatPO?ARY F0re.) CONTROL NO: 9105 FILE:

FRCti: DATE OF ECC DATZ P.IC'D LTR TWX RPT CT:ER Metropolitan Edison Co Rehding,. Pa 19603 ,

R. C. Arnold

• B-28-74 9-4-74 XX TO: , ORIG CC OTEER SENT AIC P R XXXX SENT LCCAL P;IXXX AEC 1 signed CLASS. C; CLASS PROP INFO INPUT NO CYS RIC'D DCCKET NO:

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Ltr re Abnormal Occurrence #AO 74-14, on 28 , *'*'

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Aug 74 re a loss of hydraulic shock suppressors -

on seismic class-one systems threatened to _ . - " ~

cause an Engineered Safeguard feature to be n ,- - ',_ ,,,

unable to perform its function. -

PLA'iT NAME. Three Mile Island el ,

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Y. 'g..h: / N'.Y Director F ,

Directorate of Licensing U.S. Atc=ic Energy Cc==ission Washingten, D.C. 205h5 -

Dear Sir:

0 ,

Cperating License EPR-50 -

Docket No. 5c-289 In cccordance with the Technical Specificaticns for Three Mile Island Nuclear Statien, Unit 1, we are reporting the folleving abncr=al cecurren:e:

(1) Report Number: Ao 50-289/Tk-lh (2a) Report Date: August 28, 197h (2b) Occurrence Date: August 18., 197h (3) Facility: Three Mile Island Nuclear Staticn, Unit 1 (h) Ider -ificaticn of Cccurra.ee:

Title:

Less - ?luid in Hydraulic Shcek Absorbers Type: An abnormal occurrence as defined by the Technical Specifications, paragraph 1.8d, in that the loss of fluid in three hydraulic shock suppressors on seismic class-one systems threatened to cause an Engineered Safeguard feature or syste= to be incapable of performing its intended functicn.

(5) Conditions Pricr to Occurrence: The Reactor Coolant Syste= vas in a cold shutdown ecnditien, with major plant parsneters as follevs:

Power: Core: 0 Elec: 0

$g RC Flow: O lbs/hr i40 RC Pressure: 60 psig 9103

Directorate of Licensing August 28, 197L RC Temp. 1200 F PRZE Level: 150 in PRZR Temp.: 315 F (6) Description of Occurrence: During an inspecticn of hydraulic shock suppressors en seismic class-one syste=s, the reservoirs of three suppressors were found to contain no hydraulic fluid. Two of the suppressors (MK-PR L9 and MK-PR-50) are located at the 326-fcct level of the Reacter Building en the devnstream side of the Electrc=atic Relief Valve piping. The third suppresscr (MK-MS-207) is located in the Reactor Building at the 337-fcot level along Main Steam Line A.

(7) Desi6 nation of Apparent Cause of Incident:

The less of h,lraulic fluid frc= suppressors MK-PR h9 and MK-PR-50 is believed to have been the result of imprcper installation. In the case of MK-PR h9, the line frc= the hydraulic fluid reservoir to the snubber valve was connected in such a way that the heat frc= a nearby pipe caused it to expand and break, thus releasing the hydraulic fluid frc= the reservcir. In the case of MK-PR-50, the lock nut was not properly tightened, so the unit flipped over when the electrc=atic relief piping started to vibrate, thereby alleving the fluid to drain cut of the vent plug.

The loss of hydraulic fluid frc= the third suppressor (MK-MS-207) is believed to have been tha result of ccerenent failure. In this case the cylinder seal was responsible for the less of fluid.

(8) Analysis of Occurrence: For the following reasons it is believed that the loss of hydraulic fluid frc= the three shcck suppressors did nct represent a threat to the health and safety of the public:

(a) The two shock suppressors en the electrc=atic relief piping (MK-PR-49 and 50) for the Pressurizer were installed to cetnteract the effects en the piping of dynamic (fluid) leading, not seismic leading. Had the electrematic relief valve lifted while ene or

=cre of the shock r.7presscr reservoirs was empty, the verst possible consequence vculd have been a permanent deformation of the piping. An examination of the pipes revealed no evidence of any deformation.

(b) The worst possible consequence of a loss of fluid frcs MK-MS-207 vould cecur during an earthquake when the steam lines of the Main Steam Supply System could start to vibrate. Under such conditiens the shock suppresscrs would be ineffective and the Main Stea= Line could break as a result; but because the Main Steam Supply Syste= is o conservatively designed, a -brcken line is cenuidered unlikely under any circu=st.ances.

(c) While the reservoirs cf the three shcek suppresscra vere empty, there was still hydraulic fluid in the cylinders, so that the suppresscrs cculd still partially fulfill their intended functions.

Directorate of Licensing August 28, 197h (9) Corrective Action: The felleving short-tern corrective acticns were taken by Plant Operatiens personnel to return the affected shcek suppressors to service:

(a) MK-PR h9 was replaced with a new assembly of identical design, filled with hydraulic fluid, and rotated 90 0 frcm its previcus pcsition to prevent its again teccming heated by adjacent pipes.

(b) MK-PR-50 was returned to its _ 7er pcsition, refilled with hydraulic fluid, and its leek nu. tight ened.

(c) MK-MS-207 was replaced with a new asaembly of equivalent design and filled with hydraulic fluid.

In a meeting held i==ediately after the incident was repcrted, the Plant Operations Review Cenmittee (PCRC) reviewed and approved the above actions, and recc= mended to the Station Superintendent that additienal 1cne-term corrective actions be taken as follows:

(a) contfaue the program of annual inspections; (b) accelerate the program of shock suppressor seal replacement (see the letter fren R. C. Arnold to A. Gia=busso, dated February lb, 197h);

(c) direct Plant Operations personnel to investigate any puddles of fluid fcund near piping as an indication of possible shock suppressor leakage; and, (d) examine the seal en MK-MS-207 to deter =ine the cause of its failure.

The Station Superintendent concurred with PCRC's findings and has taken st ;ps to ensure completion of the abcve listed long-tern corrective actions.

(10) Failure Data:

(a) Record of Previous Feilure:

None (b) Equipment Identificaticn:

MK-PR-49 MK-PR-50 MK-MS-207 Snubber Assembly Brand Grinnell Grinnell Grinnell Cylinder Type Miller Miller Lindco Valve Type Grinnell Grinnell Grinnell Sice 2" 2b" 2" Stroke 5" 5" 5" .

Directorate of Licensing h- August 28, 197h Sincerely,

(

R. C. Arnold Vice President RCA/JFV/cas Fil): 20.1.1/7 7.3.5.1 cc: Directorate of Regulatory Operations, Region 1 U.S. Stctic Energy Cec =ission 631 Park Avenue King of Prussia, PA 19h06 1481 551