ML20210A201

Final Part 21 & Deficiency Rept DER 85-34 Re Override Feature on Diesel Generator.New DCP Issued for Unit 2 to Modify Diesel Generator Output Breaker Circuit to Prevent Initiation of Trip Signal

ML20210A201
Person / Time
Site:	Palo Verde
Issue date:	10/28/1985
From:	Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
REF-PT21-85, REF-PT21-85-445-000 ANPP-33846-TDS, DER-85-34, PT21-85-445, PT21-85-445-000, NUDOCS 8511140261
Download: ML20210A201 (4)

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Arizona Nuclear Power Project P O. BOX 52034 e PHOENIX, ARIZONA 85072-2034 October 28, 1985

Vgg, ANPP-33846-TDS/TPS

[/f U. S. Nuclear Regulatory Commission Region V 1450 Maria Lane - Suite 210 Walnut Creek, CA 94596-5368 Attention:

Mr. D. F. Kirsch, Acting Director Division of Reactor Safety and Projects

Subject:

Final Report - DER 85-34 A 50.55(e) Reportable Condition Relating to Override Feature on Diesel Generator File: 85-006-216; D.4.33.2

Reference:

A) Telephone Conversation between R. C. Sorensen and T. Siegfried on September 30, 1985.

Dear Sir:

Attached is our final written report of the Reportable Deficiency under 10CFR50.55(e), referenced above. The 10CFR21 Evaluation is also included in this report.

Very truly yours, b

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E. E. Van Brunt, Jr.

Executive Vice President Project Director EEVB/TPS/ldf Attachment (s) cc: See Page Two 8511140261 851028 PDR ADOCK 05000528 S

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October-28 ::'1985

.Mr. D.'F.-Kirsch-4 DER 85 Page;Two?

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bg DEFICIENCY EVALUATION 50.55(e) -

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Description'of Deficiency Le?

. Engineering Evaluation Report (EER) PE-017 was' initiated to identify a-problem with the control'oflthe diesel generator output brenker during.

~ Unit'2' pre-operational testing.

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The diesel generator'(D/G) starts and remains in standby upon receipt of SIAS/AFAS. Afte'rla pariod of time with available offsite power.ethe operator may override the emergency control and stop the D/G..If loss of:

offsite power (LOP) occurs during a's'ustained SIAS/AFAS while the D/G is in ovbrride, thi D/G output breaker will'. start.to close, then trip.

These simultanehus close and trip commands to the'D/G breaker cause the anti-pumpiug relay to lockout the, breaker so the D/G cannot supply power

~to the em'ergency loads as required.

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EVALUATIONc f

'The sequence oftevents for the above condition is as follows:-

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1.- There is sustained SIAS/AFAS. Offsite power'is available.: The.D/G

f is running at standby and the~D/G output breaker is open.

2.' The operatot overrides the emergency control and places the-D/G in dreop mode in preparation to.stop the D/G.

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.As dhown on drawing 13-E-PEB-001, this opens; override relay contact 50R3 and closes relay contact 3GUP-2. Relay coil.762 remains

deenergizql and breaker stays open.-

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While-the;D/G is in the override mode', LOP occurs...Since-there is normal D/G frequency and voltage', relay contact K205 closes'for sixty seconds which cit?ses the D/G. output breaker.-

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'At?thc?same' time,anLOPsignaldefeats-theoverridecontrolandrelay contract 50R3; closes before relay contact 3GUP-2 has time to open.

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During this brief period when relay' contact.50R3 ' closes:before relay contact.3GUP-2' opens,. relay 762 is energized. With sustained SIAS/AFAS, the' closed relay contact 762 energizes relay TX which trips.the breaker..

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The. trip sh nal occurs before the sixty second. LOP close signal clears.-

Therefore F the-breaker receives both'the close.and trip signals which cause the anti-pumping circuit to lockout.' The breaker cannot reset to close until:the LOP close signal is cleared.-

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-DER 85-34J y,'

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'Per FSAR Section 8.3.4.3.d. "1) Interrupted ECCS flow to the core shall be

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' fully reestablished within thirteen seconds, and 2) interrupted emergency

'feedwater flow-to the steam generators shall be fully reestablished within fifteen seconds." The'D/G. output breaker cannot be reset to close, and the

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loads:cannot~ sequence within these time limits.

Prolonged interruption of critical' safe > shutdown operation could adversely-

' e affect the' safe operation of the plant.-

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lIt:should be noted that the D/G emergency control is overridden only' after the' operator.has. verified that offsite powe'r is available and reliable.- The e

2 occurrance;of loss:of offsite power with sustained SIAS/AFAS while th'e D/G ~

is in override mode'is unlikely.

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.The root ~cause-of~this condition is engineering error.in'the evaluation and>.,

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design of'the. specific.D/G override circuit. It does not represent a g'eneric design or design; review, error.s,The= override control for the D/G breaker allows theLD/G to'be parallel to offsite power. This'acheme is unique for the D/G w

i breaker' AnalydsofSafetyIbplications' t

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Based on'the above this condit' ion is. evaluated as reportable undc.r the l

remain uncorrected it would represent 1a significant safety condition..

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requirements of 10CFR50.55(e) and 10CFR21.,since~if this' condition were to

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i III. Correct! ion Action Thisicondition is a consequence of DCP's 10E, 2SE,'3CE-PE-013 which were i: ~

. issued to' modify the'D/G override' feature based:on' earlier preoperational

. test results.- 'DCP 2SE-PE-013 has beenDisplemented1forLUnit 2.ALnew DCP J

20E-PE-018 for, Unit L2-onlyLwill be issued to nodifytthe-D/G output breaker

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? circuit'to prevent initiation of;the trip' signal:under the~above' condition.

?A two second time delay relay,. contact was added-in placcio.ffthe.50R3 relay: _

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7 contact.'3The two:second delay'. allows ~the:3GUP-2; relay contactcto open prior 2~~

' sto the 50R3 contact closing.' Therefore.ithe trip circuitJremains,deenergized,-

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~ xthe-breaker is_ allowed to:close, Land flow is' restored:within.the: required time =

intervalsb Physical work for Unit;2 has be'en performedibyiCWO 1106385.

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DCP's:10EL3CE-PE-013 have:not been; implemented'in.Unitati and 3.

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'thisJcondition does notJexistiinith'ese unitsJ

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l f DCP's 10E, '3CE--PE-013 will be modified. to incorporate this ' change fok Units -

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