ML20029A642

LER 91-001-00:on 910121,automatic Closure of Inboard MSIV 1B21-F022 A,B,C & D & Inboard Main Steam Drain Line Isolation Valve 1B21-F016 Occurred.Caused by Personnel Error.Maint Work Request Mwr D09786 revised.W/910220 Ltr

ML20029A642
Person / Time
Site:	Clinton
Issue date:	02/20/1991
From:	Rasor S, Spangenberg F ILLINOIS POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-91-001, LER-91-1, U-601797, NUDOCS 9102270223
Download: ML20029A642 (6)

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CLIN 1QN POWLH ST ATION, P.O. HON 078. CLIN 10N. ILL1hOlb 617274Ki78. TI:LLl'ilON!: (2171935 8881 Februsry 20, 1991 10CTR50.73 Docket NO. 50 451 Docwnent Contcol Desk Nuclear Regulatory Commission Washin6 ton, D.C. 20555

Subject:

Clinton Power Station Unit 1 Licensee Event Report No. 91-001-00

Dear Sir:

Please find enclosed Licensee Event Report No. 91 001 00: 6D ltindnquat e System Ittpact ASItnitet of Turbine Modi f tnL[nn,_WnrJ;

[Mulj;ed in Automatic Containment Isolat ion Dut:lq,Jernonnel Error.

This report is being sobinitted in accordance with the requirements of 10CTR50.73.

Sincerol; yours

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NAME f t LIPHONt NLM.tp Ahla COD 4 S. E. Rasor, Director - Plant Maintenance, Extension 3204 21117_ 91315 1-181 81811 CoMPLitt ONt klNt poa a AcM cou.omlNT r assunt otscmitt D sN tnis pistat ti3i CAV84 Svlttw CovPONENT N'g 's "'p$,'((j'

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..t.c,n...,i,,.,....,,,...,,.,m...<......n.o...n.1 At approximately 1305 hours0.0151 days <br />0.363 hours <br />0.00216 weeks <br />4.965525e-4 months <br /> on January 21, 391, during the planc's s

second refuelinB outage, while the plant was in Operationn1 condi ion 4 (COLD S!!!J1'DOWN), a Group I containment isolation signal was genersted from Condenser Low Vacuum Bypass logie resulting in automatic closure of inboard Main Stearn Isolation valves 1B21-F022 A, B, C, and D, and inhoard Main Steam Drain Line Isolation valve 1B21 F016. At approximately 1315 hours0.0152 days <br />0.365 hours <br />0.00217 weeks <br />5.003575e-4 months <br />, the 'B' Control Room Operator (CRO) manual g tripped the main turbine logic. At approximately 1317 hours0.0152 days <br />0.366 hours <br />0.00218 weeks <br />5.011185e-4 months <br />, the 'B' CR0 reset the ,

Condenter 1.ow yacuum Bypass logic and reopened valves 1B21 F022 A, B, C, and D, and 1B21.F016. At the tinto of the event, main t arbino q modification adjustments and preparations for the reacts r vessel hydrostatic test were in progress. The cause of the evsnt was attributed to utility maintenance personnel error in that personnel did not properly tissess the iirpact to the plant of turbine modification during revisions '

> of the Maintenance Work Request (MVR) being used to implement the turbine modification. Corrective actions include: suspending turbine modification work, revising the MWR to include jobsteps to defeat the Group I containment isolation signal, training assistant maintenance supervisors on revising MWRs, and briefing appropriate personnel on this event.

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0l0 0 l2 OF 0l5 itxi w ~. . . ==. . ma ne w,m, DESCRIPTION OF EVENT At 1305 hours0.0151 days <br />0.363 hours <br />0.00216 weeks <br />4.965525e-4 months <br /> on January 21, 1991, with the plant in Operational Condition 4 (COLD SilUTDOWN), with the reactor [RCT) coolant temperature rt 169 degrees Fahrenheit and at atmospheric pressure, a Group I containment isolation signal was generated from Condenser [COND] Low Vacuum Bypass logic resulting in automatic closure of inboard Main Steam

[SB) Isolation Valves (MSIVs) [ISV) 1B21 F022 A, B, C, and D, and inboard Ma,in Steam Drain [DRN] Line Isolation Valve 1B21-F016.

At the time the containment isolation signal was generated, preparations for the reactor coolent boundary system leakage test wera in progren with reactor yessel ,RPV) level being raised to support the hydrostatic test. These preparations were being performed in accordance with plant technical procedure 2800.03, " Reactor Coolant System Leakage Test." The valve [V) lineup associated with this test required the inboard MSIVc to a- be open a-d the outboard MSIVs to be shut.

Concurrently but independently, plant personnel wer; implementing plant

- modification TGF008 to convert the main turbine [TRB) from full arc admission to partial arc a&nission.

Modification work'of the m'ain turbine was being controlled by Maintenance Work Request (MWR)-D09786. This modification implemented Field Engineering Change Notice (FECN; '5470 which changed $ e operating characteristics of the Turbine Control valves (TGV) {FCV). While MWR D09786-implemented a change in the operating characteristic e the TCVs, the MWR did not provide specific steps to verify TCV operav < ring the modification process. Subsequently, the assistant Control are Instrumentation maintenance (C&I) supervisor revised MWR D09786 in accordance with plant administrative procedure 1029.01, "Preparatin and Routing of Maintenance Work Requests," to incorporate steps developed from excerpts of plant surveillance procedure 9431.21, " Turbine Control and Stop Valves Scram Response Time Teut," that would allow the main turbine logic to be reset in order to verify TGV operation.

Investigation of this event revealed that this revision did not include l the nece uary piacautions, prerequisites, and limitations corresponding to the appropriate excerpts from plant surveillance procedure 9431.21

), = - used to develop jobst'ps of the MWR. AdG tionally , this revision and previous versions of the MWR did not include a system impact matrix to address the jobsteps of the MWR, since the jobsteps were assumed to be '

within the tagout boundary for the MWE.

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i The revision was > . jewed by Maintenance Planning and the Nuclear Station Engineering Department (NSED), and by the Operations Lina Assistant Shift Supervisor (LASS) and the Staff Assistant Shift Supervisior, (SASS) y rior 3 to-Operations giving the C&1 technicians permission to start work. On y January 18.-1991, the C&I. technicians began. lifting leads ta defeat main [

turbine' trips in preparation of resetting the main turbine at a later 'L time.

On January 21, 1991,-with preparations for the reactor coolant boundary system leakage test in progress, the LASS gave. permission for the y continuation of the turbine modification work that began on January 18, 4 1991. At;approximately-1305 hours, the *B' Control Room Operator (CRO)..

in accordance with MWR D09786, placed the main turbine in manual control on-the Operating Mode. switch and selected "Close Valves" on the Speed ~ Set revolutions per minuto (RPM) switch (SIS], TheB' CR0 then reset the main turbine logic by depressing the "Resot" push button, Shnrtly afterward, the 'B'-CR0 selected "800 RPM" on the Speed. Set RPM switch, and-the Turbine Stop_ Valves (TSV) 9pened in response, Openine,wf the TSVs resulted in automatic reset of the Condenser Low V , Vacuum containment. isolation logic that had previously been bypassed,

. Reset of the main turbine logic and positioning of the TSVs greater than  !

ninety percent' open resulted, by design, in the generation of a Group I _

containment isolation signal'due to Condenser Low Vacuum-Bypase._ logic. ,

This unplanned isolation signal caused'automaH.c closure of isolation

= valves 1B21-F022 A,-B, C, and D,' and.1B21 F0' At app'roximately 1315 hours0.0152 days <br />0.365 hours <br />0.00217 weeks <br />5.003575e-4 months <br />,.the main turbine Logic was-manually tripped by.the 'B' CRO, At 1317 hours0.0152 days <br />0.366 hours <br />0.00218 weeks <br />5.011185e-4 months <br />, the 'B' CR0 completed th Automatic

Isolation. Checklist, and satisfactorily varified -aL complete Group 1 i

isolauion. Tne Condenser Low Vacuum bypass logic-was reset and: isolation

valves 1B21.F022 _A, - B, J. and D,- and 1B21 F016 = were reopened. _ Turbine- - 1' modification and work under MWR-D0978_6 was suspended pending further investigation and determination uf root cause, No other automatic or_ manually initiated safety' system responses were-

- necessary to place the plant in a safe and stable condition. No other-equipment or'coeponents were inoperabic at the-start of this event such that:their inoperable condition-contributed to this event,

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-CAUSE OF THE EVENT The cause of this event is attributed to personnel error. The assistant C&T supervisor, a utility member, did not properly evaluate and identify all potential impacts on other plant systems when revising MWR D09786.

The assistant C&I supervisor was relatively new in hic ;osition and had not revised many MWRs. He determ!ned that a system impact matrix was not required for the revisions to the MWR, since the added jobsteps were assumed to be within the tagout boundary for the MWR. Required reading of plant administrative procedure 1029.01 was the extent of his training for revising MWRs.

Additionally, plant administrativo procedure 1029.01, section 8.6,

" Revision of MWRs," does not address including the necessary precautions,

. prerequisites, and limitations when using procedure excerpts within the jobsteps of revised MWRs; however, this is addressed in section 8.2,

" Maintenance Planning: Processing of Routine Maintenance Work Requests."

Investigation determined that the precas, lons, prerequisites, and limitations of plaat surveillance procedt to 9431.21 did correctly address the required plant conditions to perform :he test; however, the excerpts of this procedure used as jobsteps for K.R D09786 did not include the necessary precautions, prurcquisites, and limitations from this prccedure prior to this event.

CORRECTIVE ACTION The assistant C&I supervisor recognized his error associated with this event. He has readily admitted the error associated with this' event and

.has been counselled on the-requirements for evaluating and identifying

~ potential impacts on other plant systems when revising MWRs and performing maintenance activities.

MWR D09786 was revised to include.jobsteps for li.' ting leads to defeat a

. Group I containment isolation- . A syster impact matrix for-each TSV end L4 TGVL and for lif ting leads was completed Dr WD D09786.

' Training will'be provided to assistant maintenance supervisors, who have not been previously assigned to maintenance planning, on the requirements

1. .evising MWRs. Thi's training will include information on system

. impact matrix preparation and when a system impact matrix is required, l

This training-.is-scheduled to be completed by August 20,~ 1991, Plant admin.strative procedure.1029.01,- section 8.6, will be revised to-

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' Appropriate C&I and NSED personnel will be briefed on this event. These

- briefings are scheduled to be completed by March 20, 1991.

ANALYSIS OF EVFET This event is reportable under 10CFR50.73(a)(2)(iv) due to an automatic actuation of an Engineered Safety Feature. This event occurred while the plant was shutdown and' did not tesult in a condition significant to the safe operation of Clinton Power Station. Because main turbino admission modifications are performed only when the reactor is shutdown, this event '

would not occur during other modes of operation. Reactor vessel pressure '

monitoring instruments (PI) in place to support the primary coolant leakage test showed-no increase in reactor pressure as a result of this incident.

ADDITIONAL INFORMATION -

.All systems associated with this event responded as designed and no '

components failed during this event.

LER 86-024 00 discusses automatic closure of Group-I containment isolation valves due to Condenser Low Vacuum Bypass logic caused by utility personnel error.

For further information regarding this event, contact S. E. Rasor, Director - Plant Maintenance at 217 935 8881, Ext. 3204.

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