ML20006C145

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LER 89-048-00:on 891228,automatic Reactor Trip & ESF Actuation Occurred as Result of Loss of All Main Feedwater Flow Due to Inadvertent Tripping of Main Feedwater Pump. Caused by Personnel error.O-rings replaced.W/900129 Ltr
ML20006C145
Person / Time
Site: Arkansas Nuclear Entergy icon.png
Issue date: 01/29/1990
From: Ewing E, Taylor L
ARKANSAS POWER & LIGHT CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
1CAN019017, 1CAN19017, LER-89-048, LER-89-48, NUDOCS 9002060382
Download: ML20006C145 (4)
v • d • e


Text

. _ _ _ _ _ . . _ _ _ _ . _____ _ _ -._____ -

,f Arkansas Power & Ught Company I e w=-)APtsL n* er Littit! Rock Ar,7??O3

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Tel 501377 4000

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January 29, 1990 '

1CANB19817 U. S. Nuclear Regulatory Commission Document Control Desk Mail Station P1-137 '

Washington, D. C. 20555

SUBJECT:

Arkansas Nuclear One - Unit 1 Docket No. 50-313 License NO. DPR-51 Licensee Event No. 50-313/89-040-00 Gentlemen:

In accordance with 10CFR50.73(a)(2)(iv), attached is the subject report

concerning a reactor trip and Emergency Faedwater System actuation ,

initiated by the loss of main feedwater flow due to personnel error.c  :

Very truly yours, i  !

E.. C. Ewing -

( General Manager, .,

j Technical Support and Assessment ECE/RHS/sgw Attachment cc: Regional Administrator l

Region IV l

~U. S. Nuclear Regulatory Commission a' 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011 ,

l ~INPO Records Center 1500 Circle 75 Parkway Atlanta, GA 30339-3064 I:

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4 9002060392'900129 s R ,  !

,PDR;_ADOCK 05000313

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I Form 1062.01A NRC Form 366 U.S. Nuclear Regulatory C09rission (9 83) Approved DMB No. 3150-0104 Expires: 8/31/85 i!CEN$EE EVENT REPORT (L E R)

FACILITf NAME (1) Arkansas Nuclear One, Unit One IDOCKET NUMBER (2) IPAGE (3) 10151010101 31 II 3fl10Fl013 Ti1LE(4) Reactor Trip and Emergency f eeowater system Actuation Initiated by the Loss of Main Feedwater Flow Caused by Personnel Error EVENT DATE (5) i LER NUDSER (6) l REPORT DATE (7) 1 OTHER FACILITIES INVOLVED (8) l l l l 15equentiell (Revisioni i l i i Month! Day lYear lYear I i Number i i N%eber IMonth] Day lYent i Facility Names IDocket Number (s) i i l i i i l l l l l 1015101010I I I Il 21 21 81 61 91 Bf 91--I 01 41. 81--I Of 010111219191Of 10151010101 I i OPERATING l lTH15 REPORT 15 SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 5:

MODE (9) i NJ (Check one or more of the followira) (11)

POWERI l_1 20.402(b) l _ l 20.405(c) lJi 50.73(a)(2)(1v) l_I 73.71(b) 7 LEVELI l_ l 20.405(a)(1)(1) l_I 50.36(c)(1) 1 _,1 50.73(a)(2)(v) l_l 73.71(c)

(10) 1014121_ l 20.405(a)(1)(ii) l_l 50.36(c)(2) l_l 50.73(a)(2)(v11) l_ l Other (Specify in '

l_l 2D.405(a)(1)(111) l_l 50.73(a)(2)(i) l_ I 50.73(a)(2)(v111)(A)l Abstract below and l_l 20.405(a)(1)(iv) l_l 00.73(a)(2)(11) l _ l 50.73(a)(2)(viii)(B)I in Text. NRC Form i 1 20.405(a)(1)(v) l I $0.73(a)(2)(iii) l l 50.73(a)(2)(x) l 366A) ,

  • LICENSEE CONTACT FOR THIS LER (12) i Nanie l Telephone Number lArea i Larry A. Taylor, Nuclear Safety and Licensing Specialist ICode i 15l0111916141-13111010 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN TH15 REPORT (13)

I l l lReportabiel 1 i 'l l lReportablel Causel5ysteel Comoonent lMahuf acturert to NPRDS l lCausel$ysteel Cr300nent IManufacturert to NPRn$ I I I i l I i l i l I i i I I I l i I I I I i 1 1 I I I I I l l t 1 I I I i l i l l 1 1 1 i l i i I I i ! I I l I i i i i I i I I I i I I I I i I

$UPPLEMENT REPORT EXPECTED (14) l EXPECTED l Monthi Day liear l $UBMISSION I J l l l'l Yes (if ves. complete Exceeted Submission Date) til No l OATE (15) l I I I I I_

t ABSTRACT (Limit to 1400 spaces, i.e. , approximately fif teen single-space typewritten lines) (16) l On December 28, 1989, at approximately 1529, en automatic reactor trip and ar*.uation of the Emergency Feedwater System (EN) occurred as a result of the loss of all main feedwate flow which resulted from the inadvertent tripping of a main feedwater pump (MFP). Earlier in the day, the 'A' MFP had tripped on overspeed due to a malfunction in the pump control circuitry. Another malfunction in the trip oil system had caused an 11 second delay in the sensirg of the trip by the Integrated Control System (ICS). At the time of the event, troubleshooting was in progress to determine the cause of the delay. Operations personnel had latched, and then tripped the 'A' MFP with no observed delay in trip indication by the ICS. During the performance of a second test, an operator mistakenly tripped the l operating MFP ('B'). This action resulted in a total loss of feedwater flow which initiated an l automatic reactor trip and actuation of the EN system. The Engineered safety Features actueted, as l designed, and primary and secondary parameters were maintained within acceptable limits. The root cause of this event was determined to be personnel error. Disciplinary action was taken against the operator who tripped the wrong MFP. Additional actions are also being taken to minimize the occurrence of personnel errors. The MFP speed control circuitry was repaired and defective 'O' rings were replaced j in the pump trip device.

i 5

Form 1062.018 NRC Fore 366A U.S. Nuclear Regulatory Commission (9-83) Approved OMB No. 3150-0104 Expires: 8/31/85 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION ,

i FACILITY NAME (1) (DOCKET NUMBER (2) i LM NUMBER (6) l PAGE (3)

(

Arkansas Nuclear One, Unit One l

l l l l$equentiall IRevisioni l Yeart i Number l l Number l

_ 1015f010101 3I 11 11 81 91*-t 01 41 el--I 01 Ol01210F1013 ,

l TEXT (If more space is required, use additional NRC form 366A's) (17) l A. Plant Status At the time of this event Arkansas Nuclear One, Unit 1 (ANO-1) was operating at approximately 42 percent of rated power. The 'A' Main Feedwater Pump (MFP) was out of service.

B. Event Cascription On December 28, 1989, at approximately 1529, an automatic reactor trip and actuation of the Emergency Feedwater System (EFW) [CA) occurred as a result of the loss of all main feedwater flow which resulted f rom the inadvertent tripping of a main feedwater pump (MFP).

At approximately 1245 on December 28, while operating at 00 percent power, the ' A' MFP tripped on

  • overspeed due to a malfunction in the pump speed control circuitry. Due to a second malfunction -

within the pump's trip oil system, the pump trip was not sensed by the Integrated Control System p (ICS) [JA] until 11 seconds after thw trip. As a result of this dolay, two automatic functions did not immediately occur. The feedwater crosstie' valve'did not open, as required, and a runback (automatic loaJ reduction based on equipment availability) on loss of a MFP did nnt begin at the proper time. However, as a result of the mismatch in reactor power and feedwater flow, a power reducticn was automatically initiated. The Control Room operators immediately recognized that the MFW crosstie did not open automatico11y and manually opened the valve. The pressurizer spray valve was also controlled manually to limit RCS pressure. ICS sensed the pump trip 11 seconds after the trip and initiated a runback. The plant was stabilized at 42 percent power and the spray valve was returned to automatic.

With reactor power at approximately 42 pen:ent and the 'B' MFP in operation, an investigation was undertaken by Operations pe=sonnel to determine the cause for the delay in receiving the MFP trip indication. The ' A' MFP was latched and tripped locally with no observed delay in trip indication.  !

During a post test briefing, it was determined that the test should be repeated and that the local trip lever should be pressed and released quickly. the same operator who performed the first test was sent to trip the 'A' MFP. Radio communications were established, and a countdown was initiated to coordinate the tripping of the pump. However, the operator mistakenly entered the housing for

In addition, the EFW system automatically actuated and supplied water to both Once Throuch Steam l Generators (OTSG). The main steam safety valves lifted to relieve pressure in both OTSGs. At 1530, the auxiliary feedwater pump was started, and at 1549, [FW was secured and aligned for auto initiation. At approximately 1600, the plant was stabilized in the hot shutdown condition.

C. Safety Significance During this event, an automatic ^ reactor trip was initiat-ed by an ARTS, as designed. The EFW l system actuated properly and maintained OT5G 1evels within acceptable limits. Since the Engineered Safety Features _ actuated as required, and considering that pris.ary system parameters 1 were maintained within acceptable limits, the safety significance of this event is considered minimal.

D. Root Cause I

The root cause of this event was determined to be personnel error. The operator who l inadvertently tripped the 'B' MFP had satisfactorily performed the required task (tripping the i 'A' pump) prior to the event. However, during the second test, he failed to ensure that he was i

in the 'A' pump enclosure prior to tripping the pump, and consequently tripped the wrong pump.

E. Basis for Reportability The reactor trip and automatic actuation of EFW are reportable pursuant to 10CFR50.73(a)(2)(1v) as automatic actuations of Engineered Safety Features.

This event was also reported in accordance with 10CFR50.72 at 1627 on December 28, 1989. [

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  • . . . . CI .
  • l Form 1062.018 i NRC Form 366A U.S. Nuclear Regulatory Commission (9 83) Approved DMB No. 3150-0104 Expires: 8/31/85 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION IACILITY NAME (1) IDOCAET NUMBER (2) l LER NUMBER (6) i FAGE (3) l l l 15equentiali (Revision!

Arkansas Nuclear One, Unit One l I Yeart l Number i i Number l

~

1015l010101 31 II St 81 91--! 01 al 81--I 01 Ol01310F1013 TEXT (if more space is required, use additional NRC Form 366A's) (17)

F. Corrective Actions Disciplinary action was taken against tl~ operator who tripped the wrong MFP.

In an effort to reduce the occurrence of personnel errors, several actions were taken: j e Senior management personnel met with ANO-1 Operations personnel to discuss recent personnel error related events and to communicate their expectationb with respect to the conduct of Operations at ANO.

  • Operations personnel attended a session with a senior manager from another utility who spoke on their past experience in successfully reducing personnel errors.
  • A sono was issued from the ANO-1 Plant Manager to all Unit 1 Operations personnel reiterating management's expectations with respect to professionalism and formality and detailing the steps which are being taken to improve in these areas.

In addition to these actions, a special team has been formed to accomplish the following goals: '

1) Identify industry standards of excellence in watchstanding and develop, with Operations input, a set of watchstand? ig standards and good p-actices which should aid in reducing '

personnel errors. Other plants will be contacted or visited to gain their lessons learned for inclusion in these standards.

2) Evaluate in-plant practice to determine what is expected, understood and practiced by all levels of watchstanders.
3) Assist in promulgating appropriate standards to all operators.
4) Monitor watchstations, coach and counsel individuals on personal implementation and compilance.
5) Work closely with the shift supervisors in helping them implement the practices on their shifts.

03 Provide feedback to individuals and management on implementation progress.

A needs assessment inventory, which includes personnel interviews,is presently being conducted to icentify specific problem areas. The results of this assessment, which is scheduled to be completed by February 25, 1990, will be factored into the standards and good practices mentioned above.

The speed sensor channels for the MFPs which caused the trip of the ' A* MFP were repaired by the installation of new circuit boards.

The overspeed trip device for the ' A' MFP was disassembled and inspected to determine the cause for the delayed sensing of the pump trip. Some deformed 80' rings were found in the device which could have caused the delayed sensing of the trip. The deformed 'O' rings were replaced.

The pressure switches in the ' A' MFP trip oil system which arn associated with the pump trip signal were checked. All the switch *s were operable, as found.

G. Additional Information An event in which a reactor trip occurred due to a personnel error in which a main feedwater isolation valve was inadvertently closed was reported in LER 50-313/89-038-00.

t Energy Industry Identification System (E!!$) codes are identified in the text as (XX3 I

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