05000219/LER-1996-005, :on 960430,reactor Scram Occurred on Low Water Level Due to Personnel Error.Discussion of Event Issued to Operators & Interim Guidance Issued to Operators on Reactor Water Level Control
| ML20112J674 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 06/11/1996 |
| From: | Corcoran T, Roche M GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 6730-96-2188, LER-96-005, LER-96-5, NUDOCS 9606200386 | |
| Download: ML20112J674 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability |
| 2191996005R00 - NRC Website | |
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Post Office Box 388 Route 9 South Forked River, New Jersey 08731-0388 609 971-4000 Writer's Direct Dial Number:
June 11,1996 6730-96-2188 l
U. S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, DC 20555
Dear Sir:
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Subject:
Oyster Creek Nuclear Generating Station Docket No. 50-219 Licensee Event Report 96-005 Enclosed is Licensee Event Report 96-005. This event did not impact the health and safety of the public. Please note that the original due date for this LER was May 30,1996. On that date, an extension to June 13,1996, was requested by GPUN and granted by the NRC Region I staff, i
If any additional information or assistance is required, please contact Mr. John Rogers of my staff at 609.971.4893.
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Michael B. Roche Vice President and Director oaonn1 Oyster Creek 9606200386 960611 PDR ADOCK 05000219 S
PDR MBR/JJR Enclosure i
cc:
Oyster Creek NRC Project Manager
/[ g,'f,4 Administrator, Region I v
Senior Resident Inspector r
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GPU Nuclear Corporation is a subsidiary of General Pubhc Utilities Corporation
l NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (4-95)
APPROVED nY OMB NO. 3150-0104 EXPIRES 04/30/98 i
fN L"EC LICENSEE EVENT REPORT (LER) g=ggE i,Ngg=Agggg;gEggsgggs,sjgggg AT ON REQ E T $00 HRS PO E SS Wee'?50 ^!8u"di?id? "A"t3c"%50- 104)."B^"Ms%pM
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o ERW R N PR J (31 OFFICE ANAGEMENT F ACILITY NAME (1)
DOCKET NUMBER (2)
PAGE (3)
Oyster Creek Unit 1 05000 - 219 1 of 4
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TITLE (4) l Reactor Scram on Low Water Level Due To Personnel Error EVENT DATE (5)
LER NUMt5tM (5)
REPORT DATE (7)
OTHER FACILITIES INVOLVED (5)
MON 1H DAV YEAR YEAR SEQUENTIAL REVISION MONTH DAV YEAR F AGILIM NAME DOCKET NUM6ER NUMBER NUMBER 05000 04 30 96 96 --
05
-- 00 06 11 96 F AM NAME M TN N R 05000 ve tMJ iTING N
THIS REPORT IS SUBMIT i tD PUI lSUANT TO THE TEQUll IEMENTS OF 10 CFR s: (Check one or more) (11)
MODE (9) 20 2201(b) 20 2203(a)(2)(v) 50.73(a)(2)(i) 50.73(a)(2)(viii)
POWER
}QQ 20.2203(a)(1) 20.2203(a)(3)(i) 50.73(a)(2)(ii) 50.73(a)(2)(x)
LEVEL (10) 20.2203(a)(2)(1) 20.2203(a)(3)(ii) 50.73(a)(2)(li.)
73.71 20.2203(a)(2)(it) 20.2203(a)(4)
X 50.73(a)(2)(iv)
OTHER 20.2203(a)(2)(iii) 50 36(c)(1) 50 73(a)(2)(v) ggn sg below of 20.2203(a)(2)(tv) 50.36(c)(2) 50.73(a)(2)(vii)
)
LIC,ENUEE CONTACT FOR THIS LElt (1L)
NAML TELEPHONis NUMBER (lriciude Area Code)
Thomas S. Corcoran 609.971.4986 COMPLtIt ONE LINE FOR EACH COMPONENT FAILURE DE iCruestu IN THIS REPORT (13)
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE TO NPRDS TO NPRDS S JPPLEMENTA. REPORT R YPEG i tD (14)
EXP1CitU MONTH DAY YEAR SUBMISSION YES
'X NO (if yes, complete EXPECTED SUBMISSION DATE).
AB iTRACT (Limit to 1400 spaces, s e., approximately 15 single-spaced typewr tien lines) (16)
On April 30,1996, with a reactor startu) in progress, a reactor scram occurred at 0256 hours0.00296 days <br />0.0711 hours <br />4.232804e-4 weeks <br />9.7408e-5 months <br />.
When reactor level decreased to 139 inc les above Top of Active Fuel (TAF), a Low Level reactor scram occurred as designed. Following the scram, water level further decreased to approximately 120 inches TAF before being restored to normal. The cause of the event was a failure on the part of the operator to properly control reactor water level, aggressively take
= tion to restore level, and use the most conservative reactor water level indicator. A contributory cause was ineffective supervisory oversight in that two SRO licensed supervisors did not take positive action to halt startup activities until normal level control could be re-established.
The safety significance of this event was minimal. Adequate core cooling was maintained.
Immediate corrective action was taken to recover water level and place the reactor in a shutdown condition. A discussion of the event was issued to the operators. Guidance was issued to the operators on reactor water level control, and use of the most conservative level indicator during a reactor startup.
Additional long term corrective action will be taken to evaluate the transition point for feedwater control during a reactor start up.
NRC FORM 366 (4-95)
lNRC FORM 366A U.S. NUCLEAR RE;ULATORY COMMISSION
+95)
UCENSEE EVENT REPORT (LER)
TEXT CONTINUATION l
FACILITY NAME (1)
DOCKET (2)
LER NUMBER (6)
PAGE (3) 05000 YEAR SEQU NT AL REV Oyster Creek, Unit 1
- - 219 96 -
05 00 2 of 4 TEXT (If more space Is required. Use addroonal copes of NRC Form 366A) (17)
DATE OF OCCURRENCE The event occurred on April 30,1996, at 0256 hours0.00296 days <br />0.0711 hours <br />4.232804e-4 weeks <br />9.7408e-5 months <br />.
IDENTIFICATION OF OCCURRENCE l
l An automatic reactor scra:n was received during a reactor stanup due to a low reactor water level signal from the reactor protection system (Ells Code: JC). Water level reached the low level setpoint of139 inches TAF and initiated an automatic reactor scram as designed. This event is l
reportable under 10 CFR 50.73(a)(2)(iv).
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CONDITIONS PRIOR TO TI{E OCCURRENCE i
The reactor was in the STARTUP mode at 193 Megawatts thermal (approximately 10% of full l
power) operating at a reactor pressure of 980 psig.
l DESCRIPTION OF OCCURRENCE l
On April 30,1996, during the midnight shift, a reactor startup was in progress. The reactor was critical in the STARTUP mode at approximately 5% reactor power. Power ascension was continuing.
During the power ascension, reactor water level was in manual control with the 'C' low flow feedwater regulating valve (EIIS Component: LFRV) in service. As reactor power was increased, the turbine bypass valves (EIIS Component: BPV) automatically opened to maintain reactor pressure. Feedwater flow was increased by opening the low flow feed regulating valve. In accordance with station procedure, when feedwater flow reached approximately 600,000 lbm/hr the operator controlling reactor water level opened the 'C' main feedwater regulating valve (Ells Component: MFRV) block valve.
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NIC FORM 366A (4-95) l l
.U.S. NUCLEAR REGULATORY COMMISSION (4-95)
UCENSEE EVENT REPORT (LER)
TEXT CONTINUATION l
FACILITY NAME (1)
DOCKET (2)
LER NUMBER (6)
PAGE (3) f 05000 YEAR SE UENT AL REV Oyster Creek, Unit 1
- - 219 96 -
05 M
3 of 4
l TEXT (If more space is reqwed, use adat00nal copres of NRC Form 366A) (17)
DESCRIPTION OF OCCURRENCE (Cont.)
The operator then began preparations to place the 'C' main feedwater regulating valve in senice.
The transfer from the low flow feedwater regulating valve to the main feedwater regulating valve occurred at approximately 750,000 lbm/hr. As the operator prepared for this evolution, a third turbine bypass valve opened in response to reactor power and pressure. At this point, reactor water level began to decrease. In response to the level transient, the operator commenced opening the 'C' main feedwater regulating valve and monitored system parameters (e.g. feedwater flow, valve position) for expected response. The increase in the rate of feedwater flow was insufficient to turn the decreasing reactor water level. The reactor subsequently scrammed on reactor low water level at approximately 139 inches TAF. Following the scram, reactor water level decreased to approximately 120 inches TAF, as expected. Level control was recovered, and level was returned to the normal band. A plant cooldown was commenced in accordance with plant procedures.
APPARENT CAUSE OF OCCURRENCE The root cause of this event was determined to be personnel error in that the licensed control room operator did not adequately control reactor water level. The operator allowed reactor water level to drift low out of the normal operating band (155" - 165" TAF) and then did not take aggressive action to restore level back to the operating band. Additionally, the operator was not monitoring the most conservative (lowest reading) reactor water level indicator.
A contributing cause was ineffective supenisory oversight. There were two SRO licensed supenisors present in the control room. Even though both supenisors were aware the operator was having some difficulty in maintaining reactor water level, neither supenisor took positive action to halt the startup until normal level control could be re-established.
ANALYSIS OF OCCURRENCE AND SAFETY ASSESSMENT This safety significance of this event is considered minimal. The Technical Specification Safety Limit for reactor water level is 56 inches above the top of the active fuel. The minimum level which was reached during this occurrence was 120 inches above the top of the active fuel. Therefore, the minimum level which was reached during this occurrence was far in excess of that necessary to maintain adequate core cooling. Additionally, all reactor protection systems functioned as designed in response to the transient.
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NRC FORM 364A U.S. NUCLEAR REaULATORY COMMISSION (4 95) r UCENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET (2) l LER NUMBER (6)
PAGE (3) 05000 l YEAR SEQUENT AL REV g
l 96 -
Oyster Creek, Unit 1
- - 219 05 00 4 of 4 TEXT (Itmore space is required. use addbonalcopes of NRC Form 366A) (17)
CORRECTIVE ACTIONS
The following corrective actions were completed prior to plant restart:
- 1. A discussion of the event was issued to the operators.
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- 2. Interim guidance was issued to the operators on reactor water level control and use of the most l
conservative water level indicator during a plant startup.
- 3. The crew and individual operator performance was evaluated by Operations Management and appropriate actions were taken with the individuals involved. Additonally, Operations Management reviewed the event with the supervisors involved and stressed the importance of maintaining control of the plant during transients.
Additionally, the transition point for switching from low flow feedwater valve control to main feedwater valve control will be evaluated for possible change. This action will be completed by August 1,1996.
SIMILAR EVENTS
None.
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