ML19209A311
| ML19209A311 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 09/28/1979 |
| From: | Gahm J PUBLIC SERVICE CO. OF COLORADO |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| Shared Package | |
| ML19209A308 | List: |
| References | |
| LER-79-034-03L, LER-79-34-3L, NUDOCS 7910030508 | |
| Download: ML19209A311 (5) | |
Text
{{#Wiki_filter:. REPORT DATE: Sep tember 28, 1979 REPORTABLE OCCURRENCE 79-34 ISSUE O OCCURRENCE DATE: August 30, 1979 Page 1 of 4 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO P. O. BOX 361 PLAITEVILLE, COLORADO 80651 REPORT No. 50-267/ 79-34/03-L-0 Preliminary IDENTIFICATION OF OCCURRENC On August 30, 1979, during normal surveillance testing, the emergency diesel generator day tank levels were found to be less than 500 gallons. This is a degraded mode per Fort S t. Vrain Technical Specification LCO 4.6.1 and is reportable per AC 7.5.2(b)2. EVENT DESCRIPTIO?i: On August 30, 1979, while at 36% thermal power and 105 MW electrical power, normal scheduled surveillance testing found that the high level switches on both emergency diesel generator day tanks were inoperable. The contac ca were in the open condition which simulated a high tank level. See Figure 1. The level switch high (LSH), O1 , opens on h tank 1 vel to de-energize the diesel transfer pucp control relay (CR), . Whe. tank level decreases enough for the high level alarm to clear, th evel switch high contacts close, energizing the control relay, starting the fuel oil transfer pump and increasing tank level until the level switch high again opens on day tank high level. This action should normally maintain tank level at around 500 gallons per tank. With the level switch high, O1 , open, the day tank level fell to approxi-
, contacta closed, mately 350the energizing gallons level where switch the low Tevel switch auxiliary low4(LSL elay, , an , (3) d the control relay,
(}) , through auxiliary relay contacts, 5 . Th s started the fuel oil transfer pump and increased tank level unt 1 the day tank low level cleared. Inis opened the low switch level contacts and stopped the fuel oil transfer pump. With the high level switch open the day tank level cycled around the low switch level setpoint, approxi=ately 350 gallons. CAUSE DESCRIPTION: The level switch high setpoints were such that regardless of the tanA levels the contacts were open, which simulated high tank levels. These switches were not normally tested and since the high level alarms were up it appeared the day tank level control systens were operating properly. 7910030 b9 1083 351 .
REPORTABLE OCCURRENCE 79-34 ISSUE O Page 2 of 4 CAUSE DESCRIPTION (continued): These switches were rewired by Field Change Notice 2405 in an attempt to main-tain 500 gallons in the day teaks. A starting function was added to the high level switches which start the pu=ps whenever the high level slarms clear. However, the dead band of the switches are too wide to maintain the tank level greater than 500 gallons and still shut the pumps off before the day tanks fill up and start to overflow. CORRECTIVE ACTION: The level switch high setpoints were readjusted to the proper setpoint and the surveillance test revised to include testing these switches. The test was successfully completed. However, the day tank level control system will not maintain 500 gallons or greater in he day tanks at present, as the dead band of the high level switches, , is too great to allow the pu=p to restart before the level falls below 00 gallons. The possibility of replacing these switches with others having smaller dead bands is being investigated. The Coc:pany has previously submitted a Technical Specification change request to change the required level in the day tanks to 325 gallons (reference P-79056 dated March 7,1979) . 1083 352
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- P'JORTABLE OCCURRENCE 79-34 ISSUE O Page 4 of 4 Prepared by: dA As a B.' Ree d (M
Technical Services Technician Reviewed by:
. W. dahm Technical ervic Supervisor
- j. <
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Reviewed by: / 4, Frank MflMathie Operations Manager Approved by: 2744 Don Warembourg [/ Manager, Nuclear Production 8 1083 354
NRC FORM 366 u. a. nuwLean n euuum s un i sv=mu mwn (7 77) - 1.lCENSEE EVENT REPORT (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) CONTROL BLOCK: l 1 l l l l l lh 6 o 1 l C l 0 l F l S l V l 1 l@l 0 l 0 l- l 0 LICENSE 14 15 0 l0 NUMSER l010 l- l0 l0 l@l 4l 1lLICENSE 25 26 2.l 2l 0]@l57 CAT 58l@ TYPE Jo 7 8 9 LICENSEE CCoE CON'T a o i ,go"y , l L gl 0 j 5 l 0 l 0 l 0 l 2 l 6 768@ 69l0 l8EVENT l3 l0 QATE l7 l9 74l@ 75l 0] 9l 2l 8l 7l 9l80 @ REPORT QATE ? 8 60 61 DOCK ET NUMBER EVENT DESCRIPTION AND PROS A3LE CONSEQUENCES h o 2 10n August 30, 1979, while operating at 36% thermal power and 105 W electrical power I o 3 l it was determined that the emergency diesel generator day tanks did not have 500 gal- l o 4 llons of fuel oil as required per Fort St. Vrain Technical Specification LCO 4.6.1. o s ! This is reportable per Fort St. Vrain Technical Specification AC 7.5.2(b)2. The tanks l o 16 l had greater than 350 gallens a piece and more than 20,000 gallons were stored on site. I o 7 l There was no effect on public health or safety. RO 78-29 is similar. I o 8 l l 80 7 8 9 C E CC E $ SC E COMPONENT CODE SU S CO D'E SU E 7 o 9 8 l E l D l@ ]@ lE l@ l Il Nl S l Tl RlU l@ l S l@ l Z l @ 9 iO 11 12 13 18 19 20
,_ SE QUENTI A L OCCU R R E NCE REPcRT REVISION LE R 'RO EVENT YE AR REPcRT NO. CODE TYPE N O.
hy RE _ 21 l 7l 9l 22 l_l 23 l 0l 3l 4l 24 26 l/] 27 28 0l3l 29 lL l 30 l_l 31 l 0l 32 K N AC 0 ONP NT M T HoVRS 22 S8 I FOR 8. UPPL E MANUF C RER l33E lgl34Z [g [5 3 Zlg l36 Z[ g l 0l 0l 0l 3/ 40 l l Ylg 41 42 N[g l Nlg l Hl 1l 1l 6lg 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h [i o lThe level switch high which nor ally controls pu=p operation and keeps approximately l g l 500 gallons in the day tanks changed setpoint enough that they were inoperable and the t
, ., ; level switch lows took over control at approximately 350 gallons per tank. The high l i 3 level switches were adjusted to the nroper setecint and the surveillance coroleted. tee g l switch dead band is too wide to maintain 500 gallons at present and the problem is l 7 8 9being investigated. 80
STaSES % POWER oTHERSTATUS S RY DISCOVERY DESCRIPTicN 1 5 Wh 0 l 3l 6lh u ln N/A a
l (3_j@l Normal Scheduled Surveillance e
- 80 l
AdriviTY ColTENT mELEASED OP RELE ASE AMOUNT OF ACTivtTY LOCATicN OF RELEASE 1 6 l Z l @ l10 Zl@l N/A l l N/A l 7 8 9 11 44 45 80 PERScNNEL EXPCSURES NUM8ER TYPE CESCRIPTION i 7 l 0 ] 0 l 0 l@l Z l@l N/A l
' ' ' u 80 PER$oNNE L isauNiES NUMBER DESCRIPTICN
- 7 i a 9 9 l0l0l0l@l N/A 11 12 80 l
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1083 3S-[s ITTil8 I9Z l@l 10N/A 7 go l NRC USE ONLY , iS$uE L2j,.o_j i Nl N/A [@oESCRiPTroNb llllllllll lllj 7 8 9 to 68 69 80 & NAME OF PREPARER PHONE:}}