ML20099L540

Final Deficiency & Part 21 Rept DER 84-68 Re Robert Shaw Essential Chiller Temp Switch.Initially Reported on 840910. New Temp Switches Installed in Unit 1.Units 2 & 3 Temp Switches Will Be Replaced

ML20099L540
Person / Time
Site:	Palo Verde
Issue date:	11/15/1984
From:	Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
REF-PT21-84 ANPP-31149-TDS, DER-84-68, NUDOCS 8412010167
Download: ML20099L540 (6)

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Arizona Nuclear Power Project P.O. BOX 52034 o PHOENIX, ARIZONA 85072-2034 y Qpf g g {'j g, j l November 15, 1984 ANPP-31149-TDS/TRB REGi, 0 V K; 0

U. S. Nuclear Regulatory Commission Region V 1450 Maria Lane - Suite 210 Walnut Creek, California 94596-5368 Attention: Mr. D. F. Kirsch

Subject:

Final Report - DER.84-68 A 50.55(e) Reportable Condition Relating To The Essential Chiller Temperature Switch.

File: 84-019-026; D.4.33.2

Reference:

A) Telephone Conversation between L. Miller and K. Parrish on September 10, 1984 B) ANPP-30785, dated October 10, 1984 (Interim Report)

C) ANPP-30996, dated October 29, 1984 (Time Extension)

Dear Sir:

Attached is our final written report of the Reportable Deficiency under 10CFR50.55(e) referenced above, Very truly yours,

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EP.

am.JX E. E. Van Brunt, J r.

'JS Vice President Nuclear Production ANPP Project Director EEVB/TRB/nj Attachment ec: See Page Two g*d%Rin75*%h g/

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i Mr. D. F. Kirsch-DER 84-68 Page Two L

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Richard DeYoung, Director

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Office of Inspection and Enforcement-1 U. S. Nuclear Regulatory Commission Washington, D. C.

20555 T. G. Woods, Jr.

D.-B.

Karner W. E. Ide D. B. Fasnacht.

A. C. Rogers L. A. Souza D. E. Fowler T. D. Shriver C.'N. Russo B.-S. Kaplan-J. R. Bynum J. M.' Allen A.

C.' Gehr W. J. Stubblefield W. G. Bingham R. L. Patterson >

R. W. Welcher' H. D. Foster D. R. Hawkinson R. P. Zimmerman L. Clyde M. Woods T. J. Bloom D. N. Stover J. D. Houchen J. E. Kirby D. Canady Records Center Institute of Nuclear Power Operations 1100 Circle 75 Parkway, suite 1500 Atlanta,.GA 30339 I

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FINAL REPORTJ-DER'84-68

. DEFICIENCY ~ EVALUATION 50.55(e)-

~_ ARIZONA PUBLIC SERVICE COMPANY (APS)

. PVNGS UNITS 1, 2; 3

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Description-of-Deficiency-DuringI the integrated safeguards. pre-operational test. program the

~ Train "A" Essential-Chiller 1-M-ECA-E01 ' failed to re-start af ter a-simulated loss-of power-(LOP). Two' unrelated conditions caused this failure:

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t A.

. Bearing temperature switches that protect the. chiller motor f rom overheating will trip after a LOP. Af ter restoration of power, these' switches.will remain in the trip position until the. sensed temperature is cat

• or below reset temperature of the switches.

Normally; bearing temperature is above this reset point..

B.

The chiller is equipped with a 20-minute start-to-start anti-recycle timer circuit. This-circuit allows restart of the l

chiller in 2-1/2 minutes instead of 20 minutes, only if one of the following two conditions is met:

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1) If the chiller had been operating for 20 consecutive minutes j

prior to. shutdown, cg;

2) The previous start occurred longer than 20 minutes before the re-start.

Evaluation A.

Temperature Switches

1) The installed temperature switches were Robert Shaw Model No. MP11. They are factory calibrated so that they open.

(trip) at 221*F and. do not. close' again until the lower -

"re-set" temperature at 168'F is resched.

Their internal circuitry is designed so that on LOP _the switch opens (trips), independent of the sensed. temperature, and does not close upon return of power unless-the temperature'is below 168'F.

2)- These temperature switches have been' or will be replaced with a Robert Shaw Model No. MP33 that will close (remove trip) when power is restored af ter a LOP if the sensed temperature l'

is below the trip point. Accordingly, Unit 1 temperature.

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' switches TSH-503, -504, -505, -506,1-593, and -594 were

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replaced with ' he Robert Shaw Model No. MP33.

It.should be t

noted that.only TSH-505 and -506 monitor high~ thrust bearing.

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Final Report

- DER 84-68'

-Page Two I

oil temperature; and that only'TSH-505. failed to go'out-of the-" trip" position af ter recovery f rom a LOP event. TSH-503 and -504 monitor high motor temperature and TSH-593 and -594 monitor high.ref rigerant' discharge temperature. Only TSH-505

was. sensing a temperature above the re-set point at the time-of LOP.. Subsequent essene*-1 -chiller. tests have proven that.

these switches meet all~ their functional requirements.

3). The root cause of this problem is. that.the -Essential Chillers were equipped with temperature switches that will remain in a :

trip position after a momentary loss of power, even though I-the sensed temperature is below the trip point.,.. This condition was not addressed by. either the Bechtel Purchase Specification or information provided.by = Carrier.

B.

Start-To-Start Circuit i

1) As described previously, the Essential' Chiller will not.

I re-start for a 20-minute. period if it has not been running for 20 minutes prior.to the re-start attempti: This feature has been purposely l installed by the chiller's-manufacturer by means of a start-to-start anti-recycle timer.

This device (a, 4

20-minute timer) and its associated circuit assures that the chiller cannot repeatedly be re-started at intervals.less 4

3-than 20 minutes, since motor overheating and its subsequent deterioration would result. 'This feature had been recognized during the design of the chiller's start-circuit.

i Accordingly,' a 30-second by pass (within the Balance of. Plant -

Engineered Safety Actuation System (BOP-ESFAS sequencer) of the previously mentioned 20-minute motor re-start protection timer had been provided. However, the chiller itself :has an '

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" internal" sequencer that does not allow it to start until' typical parameters such as sufficiently hign lube oil pressure are present.

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2) During the pre-operational tests it was noted that this l

chiller start sequence can last as long as 2-1/2 minutes.

Therefore, a 2-minute time-delay relay was installed acrosa the motor re-start protection timer. This now provides for.a total of 2-1/2 minutes bypass across this timer and' allows a re-start of;the chiller'when required subsequent.to a LOP event, even though the criteria of no re-start for 20 minutes has not been met.

This override' has been approved by the chiller's manufacturer, Carrier Corporation, as long as it is used infrequently.

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Final Report-

- DER 84-68 Page Three During normal. plant operation two chillertre-starts within-a period of less,than 20 minutes can only ' occur under the conditions listed below:

a) During repetitious testing-b) If a SIAS (which' starts the chiller) is followed in less

than 20 minutes by a LOP. In that case'a one-second load shed occurs,' stopping the chiller.- Then_the chiller must-re-start.

3)1 The root cause of;this problem was the assumption at the time the chiller start circuit'was designed; with the override of-the 20-minute' start-to-start anti-recycle timer, that the chiller's " internal". start sequence will not last longer than

~30 seconds.-

II.

Analysis of Safety Implications A.

Temperature Switches The originally installed bearing temperature switches could prevent Class 1E equipment from performing its function in a timely fas'lon1.

It is estimated that under some circumstances a

it would take more than 30 minutes before the sensed temperature has decreased to the reset point, causing the switch to go to

" normal" and allow the chiller to re-start; This condition is evaluated as reportable under the requirements of 10CFR50.55(e);

since, if this condition were to' remain uncorrected, it would' represent a significant safety condition.

This project also he; evaluated this condition as' reportable under 10CFR21.21(b)(3). Thio report addresses the' reporting requirements of the regulation with the exception of'subpart VI, regarding the number and location of such components supplied to

.other. facilities.

B.

Start-To-Start Circuit Based upon-the deficiency evaluation, the condition is considered as not reportable under the requirements of.10CFR50.55(e) and/or-.

l 10CFR Part.21 as discussed below:-

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1) If the : override of the 20-minute start-to-start. anti-recycle timer fails, the chiller will re-starc either in 2-1/2 minutes or_ 20 minutes, depending upon how long the chiller

- had been operating previously.

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.e Final Report DER 84-68'

-Page Four

2) The maximum elapsed time of.20 minutes' for the chiller to.

.re-start will not cause ove' heating of.any safety-related r

component.:

.III; Corrective Action A.

. Temperature Switches

,p The new temperature switches (Robert Shaw Model=.No. MP33) were

, installed into both Unit 1 Essential Chillers (1-M-ECA-E01 andi M-ECB-E01) as per Field Change Requests 83.027-M, 83.028-M; 83.029-M, and. 83.030-M, 'which - have been incorporated into Dwgs.

Nos. M723-1, M723-2; M723-20, M723-289

- The corresponding Unit 2 and'.3 temperature switches will be replaced per DCPs 2SE-EC039 and' 3CE-EC039.

B.

Start-To-Start Circuit The Unit i start-to-start' anti-recycle timer was overridden by means-of Field Change Requests 83.218-M, 83.219-M, and 83.220HM-which ha've been incorporated into Dwgs. No. M723-20; M723-22;.

M723-289.

The corresponding changes for Unit 2 and 3 will-be' made per DCPs 2SE-EC039 and 3CE-EC039.-

IV.

References H

Letter, October 5,1984, United Technologies Carrier to Bechtel MIC 1

No. 233362 t

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