ML19262A231

Abnormal Occurrence 50-289/75-09:on 750405,hydraulic Shock Suppressors Inoperative.Caused by Loss of Fluid from Snubbers Due to Valve Design Deficiency.Units Repaired & Snubber Seal Replacement Program to Continue

ML19262A231
Person / Time
Site:	Three Mile Island
Issue date:	04/15/1975
From:	Arnold R METROPOLITAN EDISON CO.
To:
Shared Package
ML19262A232	List: ML19262A231 ML19262A234
References
GQL-0938, GQL-938, NUDOCS 7910260571
Download: ML19262A231 (4)

Text

, REPORT OF ABNORMAL OCCURRENCE AND/OR INCIDE:TI

- NRC STRIBUTION FOR PART 50 DOCKE JATERI AL (TEMPORARY FORM)

. - CONTROL NO! 425c FILE: INCIDE!Tr RE?CET FILE FROM: Metro. Edison Co. DATE OF DOC D ATE R EC'D LTR TWX RPT OTHER Reading. PA 19603 R.C. Arnold 4/15/75 4/18/75 vy ORIG CC OTHER SENT AEC POR m TO: Director. NRC *"

i signed SENT LOCAL POR CLASS UNCLASS PROPINFO INPUT NO CYS REC'D DOCKET NO:

xxr- 1 signed 50-284 DESCRIPTION: ENCLOSURES:

Ltr trans tonormal occurrence A0 50-289/75- 09 I/(j '\ '

occurring 1/15/?5 ref: inoperative hydraulic shock suppressors .t.[ ~ -

.c-s. ,

~ ' ~ - ' U ' > I. {.I_'&

PLANT NAME: Harrisburg, PA FOR ACTION /INFORMATION LCM 4/21/75 BUTLER (L) SCHWENCER (L) ZIEMANN (L) REG AN (E)

W/ Copies W/ Copies W/ Copies W/ Copies CLARK (L) STOLZ (L) DICKER (E) V' LE AR (L)

W/ Cooies W/ Copies W/ Cooies W/JCocies PAR R (L) VASSALLO (L) KNIGHTON (E) SPELS W/ Copies W/ Copies W/ Copies W/ Copies KNIEL (L) PURPLE (L) YOUNGBLOOD (E)

W/ Copics V// Copies W/ Copies W/ Copies INTERNAL DISTRIBUTION OiEG FIL C) TECH REVIEW CENTON LIC ASST A/T IND .

f N H L t'u rs pSCH RO E D E R yGRIMES R. DIGGS (L) BRAITMAN OGC. ROOM P 50GA /MACCARY GAMMILL H. GE ARIN (L) SALTZMAN GOSSICK/ST AF F KNIGHT KASTNER E. GOULBOURNE (L) ME LTZ f CASE PAWLICK! BALLARD P. KREUTZER (E)

GI AM BUSSO SHAO SPANGLER J. LEE (L) PLANS BOYD **s ST E L LO M. MAIGRET (L) MCDONALD MOORE (L) **fHOUSTON _ ENVIRO S. REED (E) CHAPMAN

• MULLER DUBE (Ltr)

DEYOUNG (L) ,.NOVAK M. SERVICE (L)

SKOVHOLT (L) ,.ROSS DICKER S. SHEPPARD (L) E. COUPE GOLLER (L) (Ltr) f lPPOLITO KNIGHTON M. SLATER (E) PETERSON P. CO L LINS /TEDESCO YOUNGBLOOD H. SMITH (L) HARTFIELD (2)

DENISE LONG REGAN /S. TEETS (L) KLECKER REG OPR LAIN AS PROJECT LDR G. WILLI AMS (E) EISENHUT

/'Fil E & REGION (2) BENAROYA V. WILSON (L) 'WIGGINTON

,,MIPC/PE (3) eVOLLMER HARLESS R. INGRAM (L) F. WILLIMIS STEELE .,,, y jy .s y t q EXTERN AL DISTRIBUTION - V el - LOCAL PDR Harrisburg, PA ,

pl - TIC (ABERNATHY) (1)(2)(10) - N ATION AL LASS 1 - PDR. SAN /LA/NY f 1 - NSIC (BUCHAN AN) 1 - W. PENN!NGTON, Rr 3 E 201 GT 1 - BROOKHAVEN NAT LAB 1 - ASLB 1 - CONSU LTANTS 1 - G. ULRIKSON. ORij L 1 - Nev. ton Anderson NEWMARK/BLUMEA 2ABI AN 1 - AGMED (RUTH GUSSM AN)

.4- ACRS S::r To LIC t.SST Rm B 127 GT

• • SEND CNLY TEN DAY REPORTS - 1 - J. D. RUN K LE'S, Rm E-201 GT 1484 201 991o200 5 77 f

+JL

- 77d

, _. - n. -m METROPOLITAN EDISON COMPANY ._. _ __ _ __ _ _ . _

PCST OFFICE 30X 542 REA CING, DENNSYLVANI A 19603 TELEPHONE 21F - 929-3601 April 15, 1975 GQL 0933 Dir ecto r Directorate of Reactor Licensing U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Dear Sir:

Operating License DPR-50 Docket #50-289 In accordance with Technical Specifications for the Three Mile Island Nuclear Station Unit 1, we are reporting the following abnormal occurrence report:

(1) Report Number: A0 50-289/75-09

- . 7 x. , ;

..m (2a) Report Date: April 15, 1975

'^

(2b) Occurrence Date: April 5,1975 ,

(3) Facility: Three Mile Island Nuclear Station Unit 1 --

(4) Identification of Occurrence:

Title:

Inoperative Hydraulic Shock Suppressors  ;

Type: An abnormal occurrence as defined by the Technical Specifications, paragraph 1.8d, in that the inoperative hydraulic shock suppressors threatened to cause an Engineered Safeguards feature or system to be incapable of performing its intended function.

(5) Conditions Prior to Occurrence:

The reactor was at hot stand-by with major plant parameters as follows:

Power: Core: 1%

Elec: 0 MW (Gross) 6 RC Flow: 140 x 10 lb/hr.

RC Pressure: 2155 psig I. 'A

-g RC Temp: 536 F ]4h4 ]

PRZR Level: 200 in.

PRZR Temp.: 650 F (6) Description of Occurrence:

During a routine hot-standby inspection of hydraulic shock suppressors (snubbers) in the reactor building, one snubber (FW-110), located on the feedwater line to the A Steam Generator inside the Secondary Shield, was found to be inoperative due to loss of fluid.

A subsequent investigation of all of the snubbers within the Secondary Shield revealed two snubbers with no fluid in the sight glass (RC-13 and RC-23, on the pressurizer spray line) and three snubbers (located at FW-109, FW-114, and FW-115 on the feedwater lines) with the defective valve model BH-1226 as described in Abnormal Occurrence Report 75-08. Although these units were not tested, it is believed that they would have been inoperative based on past experience.

The four snubbers on the feedwater lines were replaced with rebuilt, tested units of the same size and stroke. The snubber at RC-13 was replaced by an identical, tested unit and the snubber at RC-23 was inspected, refilled, tested , and reinstalled.

(7) Designation of Apparent Cause of Occurr: ace:

The loss of fluid f rom the snubbers on the pressurizer spray line and at FW-110 is believed to be due to material failure. The extent of loss of fluid from these units is indicative of seal failure although examination of the defective units showed no specific defects.

The apparent cause of the deficiency of the snubbers on the feedwater lines containing the BH-1226 valves is a deficiency in the desien of the valve, as reported in Abnormal Occurrence Report A0 50-289/

75 -08.

(8) Analysis of Occurrence:

The inoperative snubbers on the pressurizer spray line are small units (500 lb. restraining capability) . The loss of these two units would have been compensated for by the remaining 12 ucits on this line. Based on this, the event is believed not to have caused a threat to the health and safety of the public.

Although, the inoperative snubbers on the feedwater lines would have rendered those lines scismically unacceptable, it is believed that this situation could not have threatened the health and safety of the public. In the unlikely event that both feedwater lines would rupture, the sequence of e',ents would be similar to those analyzed in the steam line break accident in Chapter 14 of the IMI-1 Safety Analysis Report.

1484 203

The hypothetical accident would not , therefore, have resulted in conditions more severe than those already analyzed.

(9) Corrective Action:

Corrective action was taken as described above to replace or repair the defective units and return the snubbers to service. The snubber seal replacement program (see the letter from R. C. Arnold to A. Giambusso dated February 14, 1974) will continue . The units at RC-13 and RC-23 will be replaced with spare units at the next appropriate unit shu tdown.

The Plant Operations Review Committee and the Station Superintendent reviewed and gave their approval of these actions.

(10) Failure Data:

Previous Failures: See Abnormal Occurrence Reports A0 50-289/74-14, 74-20, 74-23, 74-25, 74-30, 75-03, and 75-08.

Equipment Identification:

Snubber Assembly Brand Cylinder Types Bo_re Stroke FW-110 Grinnel Lindeo 2 1/2" 5" FW-109 Grinnel Lindeo 2 1/2" 5" FW-114 Grinnel Lindeo 2 1/2" 5" FW-115 Crinnel Lindeo 2 1/2" 5" RC-13 Basic Engineers Tomkins - Johnson 3/4" 5" RC-23 Basic Engineers Tomkins - Johnson 3/4" 5" Sincerely,

/1 t

~~~

R. C. nold Vice Pr6sident - Generation RCA: RS B :tas cc: Office of Inspection and Enforcement - Region 1 U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406 File: 20.1.1 / 7.7.3.5.1 1484 204