ML19322E610

LER 80-011/01T-0:on 800312,investigation of Onsite Power Distribution Sys Revealed Voltage of Some 480-volt Loads Below Min Allowable W/Min Grid Voltage & Worse Case Loading. Caused by Incomplete Analysis When Transformers Replaced

ML19322E610
Person / Time
Site:	Vermont Yankee
Issue date:	03/26/1980
From:	Murphy W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19322E606	List: ML19322E605 ML19322E610
References
LER-80-011-01T, LER-80-11-1T, NUDOCS 8004010499
Download: ML19322E610 (1)

Text

"

LICENSEE EVENT REPORT LER 80-11/1T CONTQOL BLOCK: l 1

l l l l l lh 6

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

IoT 8l l9 vl TlLICENSEE 7

vl v CODE  ! si il@l o I o l-l o I oLICENSE 84 15 l o f NUMSEH o I o l- l o I o 25l@l264111111111@l LICENSE TYPE JO I

SI CA r Sd l@

COPYT i 8 5$$ dl 60 ol S l 01010 61 l 21711 @l 01311 DOCKET NUMBER 68 69 l 2 l 810 l@loM 13121618 EVENT DATE 14 REPORT D ATE lo8Jl@

EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h IoIal l Investigation of the on-site power distribution system revealed that the voltage of l I o I a i l some 480V loads is slightly below minimun allowable with minimum grid voltage and [

lo I4 l l worst case loading. The investigation also showed the 4160V system voltage to be l IoIsl l slightly higher than allowable with maximum grid voltage and light loading. Since [

lo le l l these conditions exist only with the plant in closed cycle cooling mode or cold l 10171 l shutdown, the possible consequences to the public health and safety are minimal. l l

10181 l EO 7 8 9 DE CO E S BC DE COM*9NENT CODE SUSC DE SU E lo.LJ8 7

l El Bl@ @@ l Al@ lZ lZ l Z lZ lZ lZ l@ lZ l@ ]@

9 10 11 12 13 18 19 .'O SEQUENTI AL OCCURRENCE REPORT REVISION LER Ro EVENT YE AR REPORT No. CODE TYPE No.

O su aE l8lol l-l l0l1l1l l/l 1011 l l Tl [J1 _] [0j 21 22 23 24 .'6 27 28 29 J0 J2_

TAK N AC O ON PL NT M T MoVRS S8 IT O FOR1 8 SUPP IE MAN F CTURER Lz_]@Lzl@ L1J@ Izl@ 101010101 W@ INI@ IZI@

41 I44 Z l 919191@ 47 33 J4 34 36 31 40 42 43 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS I1 IoiI The cause of this occurrence was an incomplete analysis ef the on-site power dis- l l1 Iil I tribution system when the startup transformers were replaced. By changing taps on I li12l l startup transformers T-3A and T-3B and on 4160/480V transformers T-8 and T-9, the l L' L.J l potential concerns will be corrected. Ref. "YAEC Report #1205, Aux. Power System [

t 4 l Voltage Study for VY Nuclear Power Station." l 7 8 9 80 ST S  % POWER OTHER STA TUS IS O RY OBSCOVERY DESCRIPTION 32 Ii' l51 dh l ol 9 l 91@l NA l lDl@l NRC Letter dated August 8, 1979 l ACTIVITY Co$ TENT RELE ASED OP RELE ASE AMOUNT OF ACTIVITY LOCATION oF RELEASE

[,1,_l 6,] [3.,.} @ [J,j@l NA I l NA l 7 8 9 to 11 44 45 80 PERSOt.NEL E XPOSURES NUVE E R TYPE DESCRtPTION li l 71 l o l o l 0 l@[_.j@l NA l

' ' * 2

• PERSONNEL.Nm'R,ES NUYSER DESCRIPTION NA I Li L.]8 I9 o I o I o l@l12 7 11 EJ LOSS OF OR DAVAGE TO FACILITY Q TYPE DESCRIPTION U NA l L' L.J8 9l z l@l10 7

80

' NRC USE ONLY , l

[.2,_[.,,j 7 8 9 ISSUE @oESCniPTicN @

l to NA l 68 69 lIl!llllll lll}

80 ;

I NAME OF PREPARER W. P. Murphy P E:

E 4o0401048H