ML20037B676
| ML20037B676 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 10/10/1980 |
| From: | Mcloughlin M BOSTON EDISON CO. |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| RO-80-069-01X, RO-80-69-1X, NUDOCS 8010310501 | |
| Download: ML20037B676 (2) | |
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30STc'( ZCISON C:'MPAi,t f
TI:.ZCOPY MESEA02 4
215-337-5326 nate/T w. Oct. 10.
L980 7
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Telephone.husner i
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- Dirce or, Re6 on I
? rom:
Pi** grim !fuclear Power Station l
1 Office of Inspection and Enforcement SSD #1 Rocky 'Ifit Road i
t'. S. Nuclear Regu'.accr r C ::::ission PlytnouLh, MA C2360 631 ? ark Avenue Kla3 o f P r.:s s :.A, PA 19406 ubj act:
?RCMPY RI20R-A3*.E rCCRGCE Docksc Number 10-293 ; 1icense O??.-35 i
30-069/01X-0 (3,=po r ted se r Tac.hnical Specificatisc 6.9.5a Assigned a h be:.
l 0a October 7, 1980 at 0103 hours0.00119 days <br />0.0286 hours <br />1.703042e-4 weeks <br />3.91915e-5 months <br /> with the reacter at 96 percent ateeY v mt.
Description:
stata power oceration, the-reac tor ve'ssel relie f' ralve RV 20'l-3A coened.
I'ne re ac to l-
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wna subsequenclr' stnually scraw-d and an investigacion to determine the cause of the ralief valve -acricion i ni r1:4end-i l".auca and Co rrective Action:
- vestigation r,1ve ale d that high nicrogen pressure af 160 pai resulted. in leakage sas: the seat o f the valve's :hree vay, selenoid cen ernt va q.e
-e
__ into the diaphrac: of the relief valve caus2.ng it :: lift.
Nttreuen pras.eure was rodm=
to 110 p s t.
oc11 icy Sr.atus:
96 % T.t a r=n1 MW c) Routine Scar:up g) Shutdown d) Routine Shutdown h) Refueling c) Ste:dy State v
i) Other f) Load Ch.angiag j) Not Appi:.caple i v:-inten follow-up reJor: A.11 de sent v:.:nin :wo weeks.
GLC p:rson notified Mr. Jchn Johnson Prepared by Mr.
M. Stems Mc'.p[n".in uil (2) copies c:
DirerFor Off ;-o of Management Infor:n.acion and Megrs= Contrei U.
... Eclear Regula tory t.;c==: sntor_
Woc. ington. D.C.
205.55 803037o601 g
l 305705 C-[O CY-A 7
- PILCF.1 ~ :C*C1F..P F T:EE IT47-"
SOC E".
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50 -2 K-a At t ac hm er.- te LII. 80-069/ 01X-0 Description 5
t' At 040.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> on October 7, 1980 with the seit in Eteady state operation at 96% power and reactor pressura. approximate!y equal te 1023 psi Safecy Re'.ief Vclve (S. R.V. ) 203-3A openec.
Station procedures were foll:ved and unit taken off line.
All indik;ations are that the valve retnained open until' the vessel deores surized.
Ope rat ions oe r-stnnel tried rmany ti:nes during the pressure reductien, to cycle the' valve using controls on control panel 903.
Unit was taken te cold shutdown, the drvvel; inerted, and an er.t e pade at a p--
proximately 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br /> the sace day.
i Cause and_ Corrective _ Action Investiga tion revealed enat tne inadvertent ope nin.; cf the 5.R.V. v,as caused by oxtessive Nitrogen supply pressure.
Nitregen preuure at the tim b f the etent was app r:nmately 160-163 ps1 insteac of the 110 ps. ind.:sted in the desiEL specification.
This excessive pressure resulted in sc ne leakaze throuzh the scienald valve into the dimohram of the S.R.V.
j The design of the 5.R.V.,
is such that the air pressure on the diap ara =.needed to cause the S.R.V.
to open reduces as the nain steam pressure increases.
This explains why the valve did not open until this parti:ular reactorpkessure level was re ali zed.
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s The analysis indicates that the F.R.V. shoul? have closed as the zala stean pressure decreased as long as the leakage throuch the solencii contkui vsive rs=ained constant.
However, operating practices dic:a:e that wheneke r a S.R.V.
does open or is cause d to open. attengts will be made tc closc it vka centrols em panel 903.
This was done repectedi. during the tim the vessel kas de-prosaurizinc.
When the centrol for "A" 5.R.V. was placed first in k.'te "open" position and then in the "closc" nsitirn, the sciencid contrcl valke energized and opened.
The desi gn o f the centr:
valv6 1s s ue;- that tt canneti close with either air or nitroger pressure s:re a :e r than 135 psi.
'Ihc 160 psi fitregen pressure therefore, re s ul t ed in the con t r:.
valve stayir.g en the oppn positien which prevented the S.R.V.
fre= closinz.
I Until a permanent redesign of the N2 supply syste-can be 1:r=l emen tf d, the fel-loving cc rrective tneasures have beer initiated:
1.
N2 supply pressure will be mair.:ained at 110 psi as inditated a t P1 43%.
2.
S tation procedure No. 2.1.15 "".,+.12 :- S u r ve RAr. :.- Lor" vill be rt' vi sed to reauire an ope ra to r m r2 fi ca ::." chech e' nitremt pressure onc&fshift.
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