ML20206G524
| ML20206G524 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 11/04/1988 |
| From: | NRC OFFICE OF SPECIAL PROJECTS |
| To: | |
| Shared Package | |
| ML20206G037 | List:
|
| References | |
| NUDOCS 8811220304 | |
| Download: ML20206G524 (2) | |
Text
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NUCLE AR REGULATORY COMMISSION
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SAFETY EVALUAT:CN REPORT BY THE OFFICE OF SPECIAL PROJECTS Ef';LOYEE C0fiCERN ELEl4ENT REPORT OP Mill. "VALVE CLOSURE TENNESSEE VALLEY AUTHORITY SECUOYAH NUCLEAR POWER PLANT UNITS 1 & 2 P
4 COCKET fl05. 50-327 Af4D 50-328 P
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5.bfe:t Cate;;ry:
C:e atiens (30000) v :aanical E:ui:-ent Reliability /Cesign (30100)
Sv:: ate;: y:
e Ele er.t:
Vahe C1:svre Erc lem (30111)
E pleyee Concerr.:
Ih-55-400-01 r
Tne tap s fer E!e e t Re:rt CP 30111, cated October 30, 1936, is the fcile sag e eleyce v :e.n:
Cer:e-n IN-s!.-4C0'01:
Ceneric Cen:orn - Flow C:r.tiel Valves and I
est: ati: esen/close valves in Units 1 and 2 (RhR. 515. CVC5. and RCE) do not completely close to prevert ficw of water, Average closure wt.s expressed as 96'i.
C1 is concerned that tnis i
could be detrimntal to plant operation and
- cesonnel safety, particularly after nuclear i
ocerations begin, for exatole:
instances where routine /e+ergency maintenance activities ray i
require t:tal or partial system isolation.
t C:ncern is generic in nature, with no furtnea specifics aveilable.
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II.
Su-ary of Issue i
f This is a geferic c rcern fr** 'n'atts $3r with C0ssible aaplicabi'ity at
$e*u yaF.
Alt"Ou*h t*e 00*:e'n "eations :o'.h fl:W Control valves a*0 i
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Aut *a*1: C e"./cl se (is0iatic*,) valves, chly 'ne isolati0n valves are l
Cesiga4: t: ;"eveat fl0d of water, i.e.. routine :P e-ergency Eaint.enan:e a:ttvitie.
at re:uire t:tal er cartial system isolatten.
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0811220304 8911d4 PDR ADOCK 05000327 P
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e The Se:voyah plant has an extensive valve leakage testing program in a::ordance with both ASME Section IX IWV and 10 CFR 50 Appendix J, which a;; ears to be reasonably effective.
ine ex:-essed c:n:ern of 95'. closure leads one to believe that the CI was tr :atly referrirg to tre 93'. limit switch setting on POVs. For slow a:tua i ; C.'s the pc-er ef f limit switch is typically set at 9E-99', to prevert the r: e n t e. of tre valve operator from damaging ths valve internals, for fast a:tuating MOVs, this power of f
's i mi t switch is typically set at 90-95*. for the same reason.
Althougn the limit switch is used to ceecergize the valve ector on the opening stroke, the torque s,. i t c h is used to deenergi:e the valve on the closing stroke.
The S e:;ucya h raintena. ace training for both electrical and mechanical raintea.ance workers covers not only the setting of limit switches in a::crda ce witn Secuoyah raintenance instructions (MI 11.2A, B, C, and 0),
but also Oc.ers the theory on why the limit switches are set at 98-99'. for s10 a:tuating MOVs and 90-95'. for f ast actuatirg MOVs.
IV.
C:*:lusien THe ' 0. 0 staff telieves tnat the TVA investigation of this concern was 1:e;us.e an: treir resolution cf the con:ern as describcd in Ele ent
^,e::rt C? 30;;l is acceptsb'e #0- restart, t
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