ML20085B724

Final Deficiency Rept Re Failure of Limitorque Operators of Suppression Pool Spray Valves FCV-1-74-72 & FCV-1-74-58. Initially Reported on 730604.Caused by Failure to Change Size of Mounting Bolts When Operator Size Changed

ML20085B724
Person / Time
Site:	Browns Ferry, 05000000
Issue date:	07/30/1973
From:	Gilleland J TENNESSEE VALLEY AUTHORITY
To:	Kruesi F US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085B698	List: ML20085B705 ML20085B724 ML20085B909 ML20085B919 ML20085B926 ML20085B933 ML20085B956 ML20085B966
References
10CFR-050.55E, 10CFR-50.55E, NUDOCS 8307080277
Download: ML20085B724 (4)

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• OTENNESSEE VALLEY A%THOAITY CHATTANOOGA, TENNESSEE 37401 July 30, 1973 40 gryjyggg PARTNERSHIP Mr. F. E. Kruesi, Director Directorate of Regulatory Operations U.S. Atomic Energy Comission Washington, DC 205h5

Dear Mr. Kruesi:

This is a final report on the failure of Limitorque operators of suppression pool spray valves FCV-1-7h-72 and FCV-1-7h-58 during construction of Browns Ferry Nuclear Plant unit 1. An initial report of the failure was made on June h,1973, by telephone to DRO Inspector W. S. Little. On July 5, 1973, we submitted an interim report on the failure. In accordance with paragraph 50 55(e) of 10 CFR 50, we submit the enclosed final report.

Very truly,yours, N

J. E. Gilleland Assistant to the Manager of Power Enclosure CC (Enclosure):

Mr. Norman C. Moseley, Director Directorate of Regulatory Operations U.S. Atomic Energy Comission Region II - Suite 818 230 Peachtree Street, NW.

Atlanta, Georgia 30303

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\W 8307080277 731116 PDR ADOCK 05000259 O 77 1 P PDR

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F>ROEMS FERRY NUCIEAR FIAIIT FAILURE OF LIMITORC.UE MOUIITII;3 BOLTS ON OPERATORS K)R RHR VALVES 1-74-72 AND l-74-58 An initial report of the failure of Limitorque counting bolts on operators for RHR valves 1-74-72 and 1-74-58 was made via telecon by J. C. Key and L'. D. Weber to W. S. Little, AEC-DR0i Region II Inspector, on June 4,1973, in co=pliance with 10CFR50 55(c). On July 5 ve sulnitted an interim report on the failure. This letter constitutes our final written report pursuant to 10CFR50 55(e).

During a routine investigation, the Limitorque counting bolts for the operators of suppression pool spray valves 1-74-72 and 1-74-58 in the RHR systen were found to have failed. The purpose of these two valves

, is to divert toms cooling water to the torus spray header under condi-tions where there is steem in the airspace of the torus. If these bolts failed during testing in nomal operation of the plant, torus spraying would not occur since the vnter supply to then would still be shutoff by upstrecm valves.

The failure of these Limitorque-to-valve mounting bolts occurred sometime after the manufacturer replaced the small operators (SMB-OOO) with larger operators (SMB-OO) without changing the size of the mounting bolts. The four 5/16-inch bolts in each operator were inadequate for this service, but it is not known if the failure occurred during the opening stroke or closing stroke.

The safety implications are different dapending on whether they failed during their opening or closing stroke. If the valves failed during the opening stroke, they could not be reclosed. Thus the toms would be sprayed at any time that the RER was being operated in the torus cooling mode. This would not affect the ability to cool the torus water. It would, however, cause some condensation of vapor in the tons airspace.

Unless steem bypasses the suppression pool during a IDCA, the mavimm G

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. o O amount of vapor would exist in the torus airspace on en " isolated" nonac-cident unit.

(The provisions to preclude steem bypass are discussed in the Recponse to AEC question 5.1 dated December 6,1971 of the FSAR.)

1 The conditions , existing on an "icolated" nonaccident unit are discussed and illustrated in the Response to AEC Question Q14.1 of March 25, 1971.

See page Q14.1-7 and Figure Q14.16 as suhaitted by /cendment 50 of the FSAR.

Frtxa Figure Q14.1-8, it can be seen that the maximita contribution from vapor is less than 7 psi to the torus pressure. When torus spray begins

' to ' condense the vapor, the torus pressure vill decrease; however, the 1

amount of this decrease is limited. When the total pressure in the torus 4

is about 2 psi less than the pressure in the drywell, drywell atmosphere .

vill discharge to the torus through the downcomers which are submerged under about 4 feet of water. Thus, there are no circumstances under which

- inadvertent torus spray could cause subatmospheric pressure in the torus  !

vith respect to the secondary containment.

If the valves failed during the closing stroke, they could not be reopened T1 ras the torus could not be sprayed. .

However, it should be noted that drywell spray, which is pemitted until the drywell pressure is 'only 1 psigF would limit torus pressure. ,

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When the drywen pressure is reduced to 0 5 psig less than the tozus pressure, the vacuum breaker valves vill open and vent the torus airspace to the drywell.

Thus, use of the dryvell -

spray vill limit the torus pressure to 0.5 psi greater than the drywell pressure.

On the basis of the discussion presented above we conclude that the failure of these valves has a minimal effect on safety.

The corrective measure was to modify the yoke plate of each valve so that

four 5/8' inch bolts can be used instead of the four 5/16-inch bo .

Ecpresentatives of the manufacturer (The Walvorth Co:pany) reco= mended using four 5/8-inch bolts, which is standard for mounting the larger sized i e

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- - p I \s) k Limitorque operator. Representatives of the General Elcetric Ccc:pary I.

concurred with this course of action, t The corrective action was complete on June 22, 1973.

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OL 1 1373 Tennessee Valley Authority DocketNos(50 [.

ATTN: !ir. Jacca E. Watson 50-327

. Ifanager of Pcuer 818 Power Building Chattanooga, Tennessec 37401 Gentic=en:

Thank you for your letters dated July 2,1973, July 5,1973, and July 6, 1973, w!'ich forwarded interim reports pursuant to 10 CFR 50.55(c) regarding cracks in the jacket-water temperature regulating valves of the c=crgency diesel gen-erator engines at the Sequoyah Nuclear Plant, failure of limitorqtutoperators of cu2pression pool spray _.yalves

.FCV-1-74-72 and FCV-1-74-58 at the Browns Ferry Nuc1 car Plant .Un'ifi and i def1eicncy in th~c7CIC TdfbIne'TD'DS 143)

FR! Speed Centrol and Governor at the Browns Ferry Nuclear Plant Unit 1. We are looking forward to receipt of your final repor*,a.

Tour cooperation concerning this catter is appreciated.

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Sincerely, J. C. Davis, Deputy Director for Field Operations Directorate of Ecgulatory Operations bec: DR Central Files RO Files PDR Local PDR NSIC TIC e j w t

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N.C. Mo2cicy, I FS&EB ACTION CCNTROL FORM g; 4' ,

'Y A. Action Code CDR#132 Name of Licensee and Facility TVA-Browns Ferry 1 Docket No. or License No. 50-259 Title CDR Evaluation and Followup Origin CDR Date Rec'd 7/10/73 B. FS&EB Branch Coordinator:

Bryan Dreher -

Ellis Paulus X Complet,1on Requested by C. Action Requested of:

ADREMP M&PPOB EPB RPB ADC0 OB CB TAB OOE Region II

, Date Requested 7/16/73 Con:pletion Reques ted by.

! Reference Letter dated 7/5/73 from J. E. Gilleland to F. E. Kruesi.

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D. Action Requested In accordance with PI 0600/6," Construction Deficiency Reporting,"

the TvA (Browns Ferry 1) deficiency report of 7/5/73 covering failure of Limitorque operators of suppression pool spray valves is bieng assigned to Region II for evaluation of the technical adequacy of the corrective action and the final resolution of the deficiency.

Note that TVA intends to submit a final report by 7/30/73.

E. Date Action Completed Close-out (Date & Method)

Comments: If completion date is not consistent with your work schedule, please let us know.

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J. G. Davis, Deputy Director I;.

for Field Operations Directorate of Regulatory Operations