ML18016A208

LER 97-016-01:on 970608,reactor Trip Occurred,Due to Personnel Error While Attempting to Adjust Power Range Nuclear Instrumentation Channel Following Performance of Calorimetric.Procedures revised.W/971014 Ltr

ML18016A208
Person / Time
Site:	Harris
Issue date:	10/14/1997
From:	Donahue J, Ellington M CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
HNP-97-185, LER-97-016, LER-97-16, NUDOCS 9710210120
Download: ML18016A208 (7)

Text

' CATEGORY REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9710210120 DOC.DATE: 97/10/14 NOTARIZED: NO DOCKET FACIL:50-400 Shearon Harris Nuclear Power Plant, Unit 1, Carolina 05000400 AUIH.NAME AUTHOR AFFILIATION ELLINGTON,M. Carolina Power & Light Co.

DONAHUE,J.W. Carolina Power 6 Light Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 97-016-00:on 970608,reactor trip occurred,due to personnel error while attempting to adjust power range nuclear instrumentation channel following performance of calorimetric. Procedures revised.W/971014 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

E NOTES:Application for permit renewal filed. 05000400 G

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Carolina Power 8 Light Company P.O. Box 165 New Hill, NC 27562 OCT 14 1997 U.S. Nuclear Regulatory Commission Serial: HNP-97-185 ATTN: NRC Document Control Desk 10CFR50.73 Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT UNIT 1 DOCKET NO. 50-400 LICENSE NO. NPF-63 LICENSEE EVENT REPORT 97-016-01 Sir or Madam:

In accordance with Title 10 to the Code of Federal Regulations, the enclosed revised Licensee Event Report is submitted. This report describes a Reactor Trip caused by personnel error in adjusting Nuclear Instrumentation and subsequent Auxiliary Feedwater automatic actuation due to a failure of a 6.9 kV breaker trip coil.

Sincerely, J. W. Donahue Director of Site Operations Harris Plant MSE/mse Enclosure c: Mr. J. B. Brady (HNP Senior NRC Residerit)

Mr. L. A. Reyes (NRC Regional Administrator, Region II)

Mr. V. L. Rooney (NRC - NRR Project Manager) 5413 Shearon Harris Road New Hill, NC

!'ll 'liiili!~Ill!Illlllllil/

97i02iOi20 9710i4 PDR ADOCK 05000400 S PDR

I NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 31500104 (4-B5) EXPIRES 04/30rss ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH TIUS MANDATOR INFORMATIONCclLECTION REQUEST: 50.0 HRS. REPORTED lESSONS LEARNE ARE INCORPORATED lYTO 1HE UCENSING PROCESS AND FED BACK TO INDUSTRY L'ICENSEE EVENT REPORT (LER) FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE UIFORMATIONAN RECORDS MANAGEMENT BRANCH IT+ F33L U.S. NUCLEAR REGUlATOR COMMISSCN, WASIENGTON DC 20555OEOI ANDTO THE PAPERWORK REDUCTIO (See reverse for required number of PROJECT (31500104), OFfldE OF MANAGEMENTAND BUDGET, WASHUIGTON.

205XL digits/characters for each block)

FACIUTYNAME (I) DOCKET NUMBER (2) PAGE (3)

Shearon Harris Nuclear Plant, Unit-1 50.400 10F3 TITLE lel Reactor Trip and Auxiliary Feedwater actuation AT SEOUENTIAL 'EYISION FACILITY NAME DOCKET NUMBER MONTH DAY YEAR MONTH OAY YEAR NUMBER NUMBER FACILITYNAME DOCKET NVMBER 06 08 97 97 016 01 10 14 97 05000 OPERATING MODE (9) 20.2201(b) 20.2203(a)(2)(v) 50.73(a) (2)(i) 50.73(a)(2) (viii)

POWER LEVEL (10) 026 20.2203(a)(2)(i) 20.2203(a) (3) (ii) 50.73(a) (2)(iii) 73.71 OTHER 20.2203(a) (2)(iii) 50.36(c) (1) 50.73(a)(2)(v) Specify rn Abstract below or in NRC Form 3B6A 20.2203(a)(2)(iv) 50.36(c)(2) 50.73(a) (2) (vii)

TELEPHONE NUMBER (Iirolvde Ares Code)

Mark Ellington Senior Analyst- Licensing (919) 362-2057 IN F R A REPORTABLE REPORTABlE CAUSE SYSTEM COMPONENT MANUFACTURER CAUSE SYSTEM COMPONENT MANUfACTURER TONPROS TO HERDS EB BKR 9166 T 4 EXPECTED MONTH DAY YEAR YES SUBMISSION (lf yes, complete EXPECTED SUBMISSION DATE). X NO DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single.spaced typewritten lines) (16)

On June 8, 1997, with the plant at approximately 28% power in Mode 1, a Reactor Trip occurred due to personnel error while attempting to adjust a Power Range (PR) Nuclear Instrumentation (Nl) channel following the performance of a calorimetric. The plant was performing a startup following a refueling outage, when PR Nl channel N41 was declared inoperable. The PR Neutron Flux High Setpoint, Low Setpoint, High Flux Rate, and Overtemperature differential temperature trips for N41 were placed in the tripped condition per TS 3.3.1 Table 3.3-1 Action 2 a. and 6

a. When the Plant reached approximately 28% Reactor Power the PR Nl's were adjusted to match calculated power in accordance with the calorimetric procedure. PR NI channel N41 was adjusted first. PR Nl channel N42, was to be adjusted next. As the operator unlocked the coarse adjustment potentiometer, N42 spiked, generating a negative rate trip signal on PR Nl channel N42. This signal coupled with the rate trip signal from N41 being inoperable, met the 2/4 coincidence for the PR Flux Rate Trip and a reactor trip occurred. Following the reactor trip, a breaker failure caused a non-safety 6.9 kV bus to deenergize, resulting in the trip of the only running Main Feedwater Pump and initiated an Engineered Safety Features Actuation Signal start of both Motor - Driven Auxiliary Feedwater (MDAFW) Pumps.

Harris Nuclear Plant (HNP) has performed the following corrective actions: (1) An Operation's Night Order was issued prohibiting adjustment of a PR Nl when a redundant channel is inoperable and on the use of diverse and redundant indications for instrumentation. (2) The Manager - Operations discussed this event with the operating crew. (3) The breaker for auxiliary bus 1A was replaced prior to startup. (4) Procedures were revised to provide operators an aid in identifying, at the PR channel instrument drawer, inoperable PR Nl channels. (5) Procedures were revised preventing PR Nl adjustment channels with a redundant PR NI channel in a tripped condition. (6) License operators reviewed LER 97-016-00 for lessons learned from the causes of this event.

RC FORM SFBA US. KUCLEAR REGULATORY COMMISSIO 4 95)

LICENSEE EVENT REPORT tLER)

TfXT CONTINUATION FACILITYKAME (1) ROCKET LER RUM 8ER (I) PAGE)i)

SEOUEKTIAL REVISION YEAR KUMBER KUMBER Shearon Harris Nuclear Plant ~

Unit 1 50 400 2 OF 3 97 - OI6 01 EXT Pluuuu sPosoissouudsd usu oddisiotMI soruus o!NRC Fcuus3BSAl (I 7)

VENT DESCRIPTION:

n June 8, 1997 with the plant at approximately 28% power in mode I, a Reactor Trip occurred due to attempting to adjust a ower Range (PR) Nuclear Instrumentation (NI) (EIIS code IG JI) channel with a redundant PR NI channel inoperable.

arris Nuclear Plant (HNP) has four PR NI channels (N41, N42, N43, N44). Reactor Trips are generated by these PR hannels for the following: (1) A low power trip when 2/4 PR channels reach 25% and the low power trips are not blocked.

2) A high Reactor Power trip of 109% on 2/4 PR channels. (3) A high PR rate trip when 2/4 PR channels sense an increase r decrease in Reactor Power of 5% in 2 seconds. (43 PR NI's provide input for Overtemperature differential temperature trip.

uring the startup following Refueling Outage 7 (RF07), PR NI channel N41 was declared inoperable due to exceeding 5%

ifference between N41 indication and the indication of the other three PR channels. The N41 channel was placed in the ripped condition for the low power, high power, high rate, and Overtemperature differential temperature trips per TS 3.3.1, able 3.3-1, Action 2 a. and 6 a. The operations staff continued the plant startup to approximately 28% power. Per plant rocedure, the startup was suspended to perform a calorimetric and adjust NI channels. Following data collection and alculations for the calorimetric, Operations determined PR channels N41, N42, and N43 would require adjustment of the nstrument gain due to being sufficiently out of tolerance with calculated power ( PR channel N44 did not require adjusting).

ollowing the calorimetric, the operating crew did not discuss how PR NI adjustments were going to be made with an

'noperable PR NI channel. There is a provision in TS 3.3.1 Table 3.3-1 action 2 b. that allows bypassing an inoperable hannel to perform surveillance testing on other PR channels, however HNP currently is not desighed with a bypass switch o implement this provision. In lieu of any special precautions the operator proceeded to adjust PR NI's as usual.

fter PR channel N41 was successfully adjusted, the operator unlocked the coarse gain of N42 in preparation for adjustment.

e channel spiked resulting in generation of a High Flux Rate trip on channel N42. With the High Flux Rate trip already ctuated for N41 due to performing TS actions for an inoperable channel, the 2/4 coincidence for Reactor Trip was achieved suiting in a Reactor Trip.

ollowing the Reactor Trip, non-safety 6.9 kV electrical bus 1A failed to remain energized by off-site power as designed, suiting in a trip of the only running Main Feedwater Pump (MFP) (EIIS code SJ P). With the trip of the last running MFP, n automatic Engineered Safety Features Actuation occurred which started both Motor -Driven Auxiliary Feedwater (AFW) umps (EIIS code BA P). The 1A bus failed to remain energized by off-site power due to a trip coil malfunction for the upply breaker to 6.9kV bus 1A from the Unit Auxiliary Transformer. When the breaker did not trip, a protective feature was

'nitiated that isolated bus 1A from off-site power and caused all loads on bus 1A to deenergize on bus undervoltage resulting

'n the MFP trip. The trip coil was disassembled and subsequent evaluation could not determine the cause of the trip coil ailure. Monitoring of bus 1A supply breaker performance will continue as part of the HNP Maintenance Rule program.

AUSE:

is Reactor Trip was due to personnel error in not restoring PR channel N41 to operable prior to performing gain djustments on other PR channels. Contributing factors were the inoperable PR Nl drawer was not marked locally as being ut of service and plant procedures did not contain effective direction prohibiting adjustment of a PR channel with a edundant channel in a tripped condition. Insufficient Control Room supervision involvement contributed to an inadequate rief and control of the NI adjustment evolution. The AFW actuation was due to a failure of s 6.9 kV non-safety bus to emain energized by off-site power following the Reactor Trip. Troubleshooting following the trip determined the bus was solated from off-site power due to a malfunction of the trip coil for the breaker that supplies the non-safety bus from the nit Auxiliary Transformer.

AFETY SIGNIFICANCET ere were no safety consequences associated with this event. A 6.9 kV breaker malfunctioned, resulting in an AFW ctuation. Other equipment, including safety related equipment, performed as expected. Plant parameters such as primary emperature, pressure, and Steam Generator Level were normal following the trip.

HRC FORM 666A US. NUCLEAR REGULATORY COMMISSIO (4 BS)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITYKAME (I) DOCKET LER NUMBER (6) PAGE(T)

SEO(JENTIAL REVISION NUMBER MJMBER Shearon Mar(is Nuclear Plant Unit JI'1 50 400 3 OF 3 97 - 016 01 TEXT 6lmmo Tpoooiz roqodod osoodCh'tiara ooOhOOO/NRt Arm 366A/ (I 7)

PREVIOUS SIMILAREVENTS:

LER 91-013-00 describes an event where PR NI channel N43 was inoperable. The associated trips were placed in the trip condition including channel 3 Overtemperature differential temperature trip. When surveillance testing was performed on a redundant temperature channel, a reactor trip occurred.

The LER 91-013-00 event occurred during the performance of a maintenance surveillance test. The corrective actions associated with the,LER 91-013-00 event focused on maintenance procedures and therefore were not effective for the trip discussed in this LER (97-016-00) since the calorimetric and the procedure used to adjust PR NI's are both operations procedures.

CORRECTIVE ACTIONS COMPLETED:

1. An Operations Night Order was issued prohibiting adjusting the gain of a PR NI channel when a redundant channel is inoperable.

2. The Operations personnel involved were instructed to maintain plant awareness when testing safety related components .

3. The 6.9kV bus 1A supply breaker from the "A"Unit Auxiliary Transformer was replaced with a tested spare breaker.

4. Procedures were revised to provide operators an aid in identifying, at the PR channel instrument drawer, inoperable PR NI channels.

5. Procedures were revised to prevent PR NI adjustment when a redundant PR channel is already in a tripped condition.

6. Licensed operators reviewed this LER 97-016-00 for lessons learned from the causes of this event.