ML20125B386
| ML20125B386 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 12/20/1971 |
| From: | Mayer L NORTHERN STATES POWER CO. |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 9212090339 | |
| Download: ML20125B386 (3) | |
Text
y.
43 fOL P RCed:
DATE OF DOCVuLNT, DATE ALCLIVED
- 4 0.!
Worthern states Power Wy Dec. 30, 1971 Dee. 17. 1971 li Minneapolis, Miam.
5M41 u n.
u t oo.
76,0. t.
O i,...
L.G. Mayer I
10; O A s(e.;
CC.
OtHLR Dr. Peter A. 1 Morris 1 signed & 2 cout'd At tion NttillA4T CONCupttNCE l
OArt aN$wtatD
=o Acpo ictssa T co--eNT Q
ny:
CLAb ts tF.
PObi Of $ 1CL i 4LL 000(.
E_
.c o No.
50-263 DLbCheP T40N. ( Must lie Uptl466d..d) att(RALD TO DATE RECitVED gy DATE Ltr reporting a condition en 11-20-71 Enuth 12-1071 invoHing failure of ECCS pump start w/9 cys for ACTION Ross permissive switch & relay....
y, gg,gg, STRIBUfl05:
Dr. samauer
'"'w*"*'*
%g File Cy Rosen ABC FDR W. Laubem 000-Rm-F-504,-A
- 2. Celmer c - 11ance 4 2)
Nuntsing & ttaff-x
- m. f i
"l'"2*"
DONOT HOW A EJeAAK &, tua+ N
""R"*2!1
.ICHOWIFDGFD
.yd w
n.C. e.
l unvak nL i
u.s. avouc tutnor couuissioN M All CONTROL FORM roau ase-saes e v.s. Govt nnut N T pmiw YeNG orrict t s 7 t wa s.e s a
'0' i
9212090339 711220 PDR ADOCK 05000263
-S PDR
Regulatory rh Cy.
NORTHERN STATKs POWER COMPANY Minneapolis, Minnesota r
A
/
- )
December 20, 1971 3
occunts uwc v>
h_ DEC 271971.* -5 'd Dr. Pet er A. Morr is, Di rector gD 6
Division of Reactor LicensinC EsN k hk
/. g~. h.h.. D [N' 7 United States Atomic Enc r gy Commi n ion put CLDE H
%ashinc~ ton, D. C. 20545 fr N. :e 7
g a
pg
Dear Dr. Morris:
3.
,y e a>
gr rgb WNTICELLO f;UCLEAR GENERATING PLANT Docket No. 50263 License No. DPR-22 C#
Failure of ECCS Pump Start Per nissive Switch and Relay A condition has occurred recently at the Monticello Nucitar Generating Plant which we interpret to be reportable in accordance with Section 6.6,0.1 of the Tcchnical Speci ficalions.
The Region iIi Compiiance office has bcon notified of thi s event.
Summar v of Occur r ence On November 20, 1971, whilc performing a regularly scheduled surveillance test, the trip setting of f CCS pump start permissive switch PS 2-3-53A, switch #2 was found to be 433 psig,12 psi belew the required trip cetting of A450 p,sig.
During thir survcillance test it was also discovered that a relay in the ECCS pump start pcrmissive logic failed to energize with the pump start permissive switch PS 2-3-53A, switch #1, closed.
An investigation of this occurrence revealed that the two switches contained in PS 2-3-53A were not designed for the 125V DC application for which they were being used.
This investi ation also revealed that the air cup on the failed C
relay was too large requiring a hi h pull-in voltage to energize the relay.
C New owitches desi ned for 125V DC use will be purchased and installed for all C
instruments of this type.
The pump permissive switches have been calibrated to tr ip at 460 psic, to allow for setpoint drift.
The relay air gap was reduced and the pull-in voltage was adjusted to less than 80fe of rated voltaCe. The relay was tested and found to operate satisfactorily.
Surveillance testing of this instrumcnt will be performed more frequently until the drif t problems have been corrected.
The correct relay pick up voltage setiirg will be vcrificd with the manufacturer and the setiings adjusted as necessary on this and all similar relays.
56/5 5
[b e
2 A Si ni ficant Optrat ing I. vent repoi t has l>een wr itten for this occurrence C
and wil; Le available to the Recion lli Ccepliance inspec t or for review durire hir next visit.
Yours very truly,
[. M L. O. Mayer Director of Nml<:ar Support Serviceo LO'//Gi1J/mm m-u mium i