ML20244D463

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Forwards Correspondence W/Hauptabtei Lung Furdie Sicherheit Der Kernanlagen Re Use of Gulf & Western Ball Valves at Leibstadt Nuclear Power Plant.Valves Similar to MSIVs Used at Nine Mile Point Unit 2
ML20244D463
Person / Time
Site: Nine Mile Point Constellation icon.png
Issue date: 09/13/1985
From: Haughey M
Office of Nuclear Reactor Regulation
To:
Office of Nuclear Reactor Regulation
Shared Package
ML20238A944 List:
References
FOIA-87-438 NUDOCS 8509230755
Download: ML20244D463 (1)
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SEP 131985 Docket No. 50-410 NOTE TO: Centr'al File .

FROM: . Mary F. Haughey, Project Manager Licensing Branch No. 2. ' -

Division of Licensing

SUBJECT:

CORRESPONDENCE BETWEEN THE NRC AND THE HAUPTABTEILUNG FUR DIE SICHERHEIT DER KERNANLAGEN CONCERNING THE USE OF GULF AND WESTERN-BALL VALVES AT THE LEIBSTADT NUCLEAR POWER STATION The enclosed information includes correspondence between the NRC and the Hauptabteilung fur die Sicherheit der Kernanlagen concerning the use of Gulf and.

Western Ball Valves at the Leibstadt Nuclear Power Station. These are the same valves that are used as Mainstream Isolation Valves (MSIV's) at Nine Mile Point 2.

The enclosed correspondence documents the operating history and problems with these valves at the Leibstadt Nuclear Power Plant in Switzerland. A copy of the May 23, 1985 report was made available to Niagara Mohawk Power Corporation for their information.

Mary F. Haughey, Project Manager Licensing Branch No. 2  !

Division of Licensing l l

Noted: Walter R. Butler ~

Enclosure:

As stated DISTRIBUTION Docket Fils LBf2 Reading PRC System MHaughey EHylton JRead PDR LPDR

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Mr. F. Weehuizen . \

g Bundesamt fur die Energiewirtschaft Hauptabteilung fur die Sicherteit der Kernanlagen -

.5303 WURENLINGEN. Switzerland

Dear Mr. Weehuizen,

At a recent CSNI/GREST meeting I met Mr. G. Prohaska, who refe d me to you as the best contact for some information concerning the ss experience wi,'.h a' specific BWR main steam isolation valve (MS ). We are currently in the process of evaluating the potential for eakage of a new double-seat.MSIV for a U. S. plant for which no previ U. S.

experience exists. We understand that a similar valve is in talled at the Leibstatt BWR in Switzerland. Furthermore, we have heard that some difficulties were encountered in making these valves meet agp11 cable leakage criteria. I would appreciate any information conceening the pre-operational testing and operational experience with the MSIV's on the Leibstatt plant. If you can make the information available, our interest centers on: '

1 The leak rates encountered in pre-operational testing i{ Any additional test data foliowing start-up I-

3. Your assessment of the causes of leakage, particularly if

' excessive leakage was encountered

, .,, 4. Corrections or modifications, if any, to the valves to j improve performance. -

Your help with this issue will be much appreciated. ,

l Sincerely..

L ,-

Walter F. Pasedag / /

i Accident Evaluation Branch

. Division of Systems Integration

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y J' e i Hauptabteilung for die Sicherheit der Kemanlagen Division Principale de la Securfte des installations Nucleelres

[' Divisione Principale de!!a Sicurezza degIllmplantl Nucleari .

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P 056/993011 in, ,,,,, , Oct. 26, 1984 Hr. W.F. Pasedag v g;;y,;'*;g Accident Evaluation Branch Division of System Integration in, zcen.a United States Nuclear Regulatory Commission Washington DC 20555 i 74'. O BW/re ' '

Leibstadt ball-type valves Dear Mr. Pasedag; Last October you asked for specific information about the.Le'ibstadt ball-type valves, referring to our Mr. Prohaska.

Enclosed please find our report about the subject. If you need more information, please specify the points in question.

Sincerely, h&'

W.Br$ndli Division of Reactor Safety Enclosure SWISS FEDERAL NUCLEAR SAFETY DIVISION 2 copies of tiSK 12/240 E

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'/ j'{ May 03, 1985 HSK 12/240 Typ i Chor:hter;

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Hauptabteilung for die Sicherheit der Kernanteeen klassihkotion:

f Divleton principale de la Securtti des Installetkms Nucleelten Technical Report ,

Diviolone principale per la Sicurene degillmplanti Nucleari seertwiter: visum:

5303 Warentingen W. BrEndli e Tel. ose s so2s sa F. Weehuizen /re M rrenki, te no, seemstand : ,, seite - 3 """'*

Leibstadt NPP ,

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Experience with ball-valves in the main steam and feedwater lines I at Leibstadt Nuclear Power Station The nuclear power station Leibstadt, a GE BWR/6 plant with a Mark ,

III Containment, has 6 Energy Product Group shut-off valves located i in the steam tunnel. A 33" diameter ball-valve is mounted on each of the four main steamlines between the outer containment isolation valve and turbine building penetration. A 27" valve is siinilarly

mounted on each feedwater line. Ball surfaces are of tungsten carbi-de with a stellite underlay.

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.j The feedwater shut-off valves are closed during reactor shut-down,  !

E enabling the' condensate and feedwater system to be purged through .

A the condensate polishing system. The shut-off valves on the main  !

} steamlines act as an activity release barrier against post LOCA

.'i leakage through the main steam isolation valves.

t i The choice of this type of valve was dictated by the tight space re.

[ .quirements at the installed location, as well;as by the manufactu-

' rer's guarantees concerning leak tightness and seismic design. Other i known and proven valves would have needed too much space. (Shut-off

[ valves, in addition to the isolation valves, were not provided in g the original project.)

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Verteiler : NRC Washington Ablage :

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4 During pre-operational tests failures and damage occurred on severa'i occasions:

On the 5th October 1982 one of, the two feedwater valves remained . leak tight during'a' pressure test only'up to 24 bar/341 pst. At about.25 bar/

356 psi a serious leakage occurred. During a later test of the same val-ve a leakage of about'220 kg/h was measured at only 6 bar/85 psi. When the displacement pump used for leak-testing was stopped, the. pressure in the volume (110 m3) being tested sank to 1 bar within 5 minutes. The

, other. valve remained leak tight up to 169,bar/2404 psi. The four valves on the main steam lines passed the leak rate test.

3 After testing all six valves were opened up. All showed evidence of- I interior corrosion. The sliding spools, which bear on the surfaces of the ball, showed circumferential wear on one side of the valve and nickeldepositionontheother(Seeappendix1,remarkA.)TEespring loading on the sleeves was reduced and a new seal (manufacturer " Titan")

was installed. The housing was ground-out cicumferentially to obtain more radial clearance for the spools.

On the flange for Jhe valve bonnet a part of the surface was machined and provided with a hard facing. The lantern rings on both upper and lo-wer bearings were turned down. The self-sealing closure was dam, aged on the sealing surface in contact with the pressure seal. This surface also received a hard facing. The metallic sealing rings were replaced by seals of a softer material (remark B).

The thin tungsten carbide surface of the valve ball showed damage due to broken-out pieces in some areas. As a result of the damage, a review of the matching of ball and seat materials was undertaken by Prof. Grosch at the Technical University, Berlin. He expected more problems in the future from loss of the hard-metal layer. .

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- 'In the spring of 1983 problems with the valve drive mechanism' arose. Du-ring closure of one valve on the main steamline plastic deformation of the frame assembly occurred. These valves are closed by spring-force and

- are jacked open hydraulically,. The frames on all valves Nre strengthened.

The pump and motor of the electrohydraulic control crf the affected valve were replaced. Improvements to the hydraulic parts of the solenoid con-trol valves were intiroduced. On all the m6in steamline valves the drive for manually tripping the valves closed was replaced. On one valve the main hydraulic cylinder was replaced twice, once because the drive

% spindle was bent and then when the cylinder was scored.

lm With all these problems, repairs and changes the management lost conff-dence in the reliability of the valves.

- In summer 1985 the H5K allowed KKL to replace the feedwater valves by non-return valves of the type already used for containment isolation in these lines. Wedged-plate slide-valves mounted at the upstream end of I

, 'the lines in the turbine building now enable purging to be carried out through the condensate polishing system without involving the' primary system.

e No similar solution was available for the main steamlines, so the four ~

large ball-valves will remain in operation. Duri'ng normal reactor opera-tion.they will remain open. They will be tested only during the annual shutdown, when the lines are cold and not under pressure, j 3

KKL has still the intention to propose other solutions, but only after ,

I experience about the behaviour of the valves .in operation, and data con-cerning the leak-tightness of the inner and outer containment isolation valves, has been gathered over a period of several yoers.

To sumarize, the ball-valves and their operators in Leibstadt have had se-ver,e.and repeated problems. A solution has been found for the feedwater :li-nes by means of non-return and slide valves. In the long term the manage-ment hopes to be able to change to another type of valve on the main steam- )

l lines.

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