ML20086D769

Updated AO 73-09:on 730410,microswitch Installed in DPIS-129B Failed to Actuate at Required Setpoint.Defective Switch Replaced,Actuating Arm Realigned & Trip Point Actuation Rechecked Repeatedly

ML20086D769
Person / Time
Site:	Vermont Yankee
Issue date:	04/13/1973
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086D773	List: ML20086D769 ML20086D775
References
AO-73-09, AO-73-9, VYV-2607, NUDOCS 8312050099
Download: ML20086D769 (2)

Text

, .

O O .

if '

i -J

' ) VERMONT YANKElc NUCLEAR power CORPORATION sevcNTY OcVEN OHOVC STRcCT

! IlUTI.ANo, VimFIONT 03701 VYV-2607 "*

P.O.DOX 157 VERNON, VERMONT o5354 April 13, 1973 Director t- N' Directorate of Licensing I United States Atomic Energy Commission O '

i Washington, D.C. 20545 g (['iL) y

REFERENCE:

Operating License DPR-28 d App,2 OG73 *hg}

i Docket No. 50-271 g ir Abnormal Occurrence No. A0-73-09 F E /, )

,ke.

Centlemen:

' i / w, As defined by Technical Specifications for the Vermont Yankee n..cio.c unwar gration, socrinn h.i.n.<i, we are vennrring rno rniinwing g Abnormal Occurrence as A0-73-09.

. ; At approximately 1115 on April 10, 1973, while performing routine rV quarterly surveillance on the LPCI break detection logic (i.e., A>B d/p

.-c f-J~ acrossrisers),amicroswitclLJ)nstalledinDPIS-129Bfailedtoactuateatfdh the required setpoint of 1 (+.5 psid as spect. g t nhin T 1.2.1 of

-f TechnicalSpecifications(.'ThemicrisiIwitchac!uatingarmwasmechanically

- s bound and failed to drop into the cam valle) at its required setpoint.

yf,1[2 Functionally, this switch, 2-129B, operates in conjunction with switch 2-129D and combined they actuate a relay in their respective string to 7- close loop B LPCI valves and actuate Loop A recirculation valves. The reactor was operating at approximately 75% power at the time of this incident.

In compliance with Note 2 of Tabic 3.2.1 of the Technical Specifications the channel was promptly made operabic by replacing the defective switch with a bench tested new one, realigning the actuating arm, and rechecking trip point actuation repeatedly. Operation was satisfactory after repeated actuations and the channel was d clared operabic by 1430 on April 10, 1973.

l 8312050099 730413

{, p ,o -

PDR ADOCK 05000 S

[

S l

msurMao' W

\

. . , p p d VERMONT Y'/ /t(EE NUCLEAR PGWER CORPORATION

_l Directorate of Licensing

, April 13, 1973

,' Page 2 The Plant Operations Review Committee reviewed the reported incident and concluded that the newly installed switch, and other similar ones, be closely observed for any indication of bound actuating arms at subsequent 30 day functional surveillance tests.

Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION P

M O. -

B.W. Riley ]

Plant Superintendent BMB/kbd ,

6 t

i