ML20206K181

Responds to Re Event Notification from North Atlantic Energy Service Co Indicating That One of Seabrook Two EDG May Have Been Inoperable Since June 1997. NRC Insp of Problem Not Yet Completed

ML20206K181
Person / Time
Site:	Seabrook
Issue date:	05/07/1999
From:	Blough A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:	Haberman S SEACOAST ANTI-POLLUTION LEAGUE
References
50-443-99-02, 50-443-99-2, NUDOCS 9905130090
Download: ML20206K181 (3)

Text

(,

n '

May 7, 1999 i

l

)

Mr. Steve Haberman Field Director

' Seacoast Anti-Pollution League P.O. Box 1136 Portsmouth, NH 03802

SUBJECT:

Response to Letter Dated April 9,1999, Discussing Seabrook Daily Event Report, Dated April 1,1999

Dear Mr. ~ Haberman:

I am responding to your letter to me dated April 9,1999, regarding your concems about an event notification from North Atlantic Energy Service Company (NAESCO) indicating that

- one of Seabrook's two emergency diesel generators (EDG) may have been inoperable since June 1997. We also have concems re0arding this event. Our inspection of the problem 1 described in the event report is not yet completed. The results of our inspection will be 1 discussed in NRC Inspection Report 50-443/99-02, a copy of which will be provided to you. In the meantime, I'd like to address'some of your concems.

NAESCO reported that the "B" EDG may h' ave been inoperable during the last operating cycle, .

and that the "A" EDG was unavailable for short durations during the same time period for ]

maintenance and testing, for a total of about 7.5 days. The EDGs are not the only sources of 1 power in response to accident conditions at Seabrook. Two off-site power sources are also available for response to accident conditions at the site. The EDGs are necessary to respond to '

events involving a total loss of off-site power. -1

lt is important to note that while the "B" EDG may have been inoperable for an extended period

of time because, after starting, it may not have automatically powered required equipment, this equipment could have been manually connected to the EDG as specified by station emergency procedures.- So, while the "B" EDG was functional but inoperable, it remained available for use ,

by the operators had a total loss of off-site power occurred.

The licensee has completed its investigation into the root causes for the relay problams and identified corrective actions to minimize recurrence as described in the enclosed Licensee Event

\

Report (LER) 50-443/99-001.- The LER discussed a combination of two factors which led to the relay failures including: improper relay calibration settings and a high relay contact impedance '

caused by the build-up of corrosion products. As part of the corrective actions for this event, the

. licensee has replaced all similar relay intemals used in safety-related applications with new components? The licensee also confirmed that the relays were properly calibrated prior to installation, in addition, the licensee has revised the procedure for testing the relays in the future to incorporate the lessons teamed from this event and to visually inspect the relays for signs of corrosion.

s 9905130090 990507 3 ADOCK 0 ig gDR, IE:01

~

-0FFICIAL RECORD COPY

I Steve Haberman 2 1

As discussed above, while the relay failure caused the 'B' EDG to be inoperable for an indeterminate period of time during the last operating cycle, plant operators still would have had l the ability to power the associated equipment on the 'B' vital bus using the 'B' EDG. The relay failure affected the automatic loading of the equipment on the bus, resulting in the reported condition. In LER 99-001 the company addressed a number of hypothetical accident scenarios associated with the relay failures and concluded that these failures would not have compromised the integrity of the fuel or the containment building and therefore, would not have increased the radio;ogical consequences of an accident.

I In conclusion, we have reviewed the licensee's actions to correct this condition and prevent I recurrence and found them acceptable. The degraded relays identified by the test have been replaced and tested prior to restart. We willinform you of the results of our inspection, including l any possible enforcement action resulting from this matter when the inspection has been completed.

Sincerely, Original Signed by:

Richard V. Crlenjak for A. Randolph Blough, Director Division of Reactor Projects Docket No. 50-443 l

Enclosure:

Seabrook Station LER 99-001-00 cc w/ encl:

j T. Feigenbaum, Executive Vice President and Chief Nuclear Officer .

B. D. Kenyon, President - Nuclear Group J. S. Streeter, Recovery Officer - Nuclear Oversight W. A.' DiProfio, Station Director - Seabrook Station R. E. Hickok, Nuclear Training Manager - Seabrook Station D. E. Carriere, Director, Production Services

i. L. M. Cuoco, Esquire, Senior Nuclear Counsel l W. Fogg, Director, New Hampshire Office of Emergency Management

D. McElhinney, RAC Chairman, FEMA RI, Boston, Mass R. Backus, Esquire, Backus, Meyer and Solomon, New Hampshire D. Brown-Couture, Director, Nuclear Safety, Massachusetts Emergency l Management Agency F. W. Getman, Jr., Vice President and General Counsel - Great Bay Power Corporation R. Hallisey, Director, Dept. of Public Health, Commonwealth of Massachusetts D. Tofft, Administrator, Bureau of Radiological Health, State of New Hampshire S. Comley, Executive Director, We the People of the United States l W. Meinert, Nuclear Engineer l

t u

ry

(

0

-- Steve Haberman 3 ,

Distribution w/ encl: 1 H. Miller, RA/J. Wiggins, DRA

.' C. Anderson, DRP i M. Tschiltz, OEDO E. Adensam, PD l-3, NRR ' -

J. Harrison, PD l-3, NRR ~

I R. Correia, NRR (RPC)

D. Screnci, PAO, ORA R. Summers, DRP -

S. Barr, DRP  !

R. Junod, DRP - l NRC Resident inspector. .

inspection Program Branch, NRR (IPAS)

DOCDESK Region I. Docket Room (with concurrences) l PUBLIC J Nuclear Safety Information Center (NSIC)

I I

I J

DOCUMENT NAME: G:\ BRANCH 5\SAPLLTR3.WPD l To receive a copy of this document, Indicate in the box: "C" = Copy without attachment / enclosure ."E" = Copy with attachment / enclosure "N" = No copy OFFICE .- Rl/DRP p . l Rl/DRP l Rl/ ORA l Rl/DRP ,, l NAME RSummers'f.<A e CAnderson C/# DSchryt:i ABloughh /s - ,

05/ /$

DATE 05/5799 {~ 05/7/99 05f//99 OFFICIAL RECORD COF%- /

JAN-23-1900 15:45 603 474 9018 P.02

{ USNRC REGION 1 SEABROOK-t N:rth Atlanile Energy Service Corporatica gg.g P.O. Box 300 Seabrook,NH 03874 Adaritic 1603342 ,ssi The Northeast Utilities System April 28,1999 Docket No. 50-443 NYN-99047 AR#99004956 ACR 99-1158 ACR 99-1159' United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Seabrook Station Licensee Event Report (LER) 99 001-00 Emergency Diesel Ger-iger Inoperability Due to Westinghouse AR Relay Failures Enclosure 1 is Licensee Event Report (LER) 99-001-00 for an event that occurred at Seabrook Station on March 29,1999.~ This event is being reported pursuant to 10 CFR 50.73(a)(2)(i) and

'10 CFR 50.73(a)(2)(v). ' Enclosure 2 is a list of North Atlantic Energy Service Corporation (North Atlantic) commitments made in response to this LER.'

- -Should you require further information regarding this matter, please contact Mr. James M.

Peschel, Regulatory Compliance Manager at (603) 773-7194.

Very truly yours,_  !

NORTH ATLANTIC ENERGY SERVICE CORP.

Y){.)) l*

[ fed'C. Feigenbado Executive Vice President and -

ChiefNuclear Officer cc:- H, J. Miller, NRC Regional Administrator -

J. T. Harrison, NRC Project Manager, Project Directorate 1-2

R. K. Lorson, NRC Senior Resident Inspector .

03DSOW kffe

JAN-23-1900 $5:51 USNRC REGION I SEABROOK 603 474 9088 P.12 l J

, . , l I

E 1

)

i l

ENCLOSURE 2 TO NYN-99047 I 9

4 48 1

4 i

1 J

l

. 1 e O 1

i s

e t

9

I JAN-23-1900 15:52 USNRC REGION I SEABROOK 603 474 9018 P.13 1 North Atlantic Commitments Contained in NYN-99047

~

l Description of Commitment ARM 9004956-02 The AR relay intemals and covers in both the Train A and Train B EDO EPS's will be replaced with new units prior to startup from the current refueling outage. The existing relay cases will be cleaned to ,

remove any corrosion residue.

ARM 9004956-03 The replacement AR relay internals for the Train A and Train B EDG EPS will be confirmed to be properly calibrated before installation.

AR#99004956-04 The 46 non-safety AR relays associated with the electrical distribution system will be periodically visually inspected for corrosion and gasket degradation, their contacts will be burnished and the relay cover gaskets will be replaced.

I I

i I

1 TOTAL P.13

/JAN-23-1900'!15:45- USNRC REGION I.SEABROOK . 603 474 9018 P.63' 7 ';j. , ,. .,, .

4 . -

.i -

t t

ENCLOSURE 1 TO NYN-99047-t E 1 6 I

L ..

4

' k 7

S i

i

-l l

\ v l

t.

l t

2

.)

JAN-23-1900 15:46 USNRC REGION I SEABROOK 603 474 9018 P.04 NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSloN APPnovan av oane NO,3160 0104 p.gg3 EXPIREe 04r33fte

.* WswNoN.aNNcN Mas nsMnMasN

aWc eE#s"*n E #UnE i ap ,Ja"4T4 LICENSEE EVENT REPORT (LER)  !$We.Vt.'Mf.a"g!nonvooNNE

$*NNA?h!EEoUn?? eN"

l

\

(See reverse for required number of I digite/cherectere for each block)

- 1r - m -----m-- uu raeme ,

Seabrook Station 05000443 1 of 8 l

Emergency Diesel Generator Inoperability Due to Westinghouse AR Relay Failures EVENT DATE (5) LER NURSBER (5) recrursi DAN (7) OTMBR FACluTIES INVOLVED (5)

F^GiuTY NAMt pocm muuman MONTM OAV YtAR YEAR 5tuukNTIAL REViervN MONTH DAY YEAR NUMBER NUMBER 99 *^5*'""* Gm "U""

03 29 99 99 00t 00 04 28 I

1. TMIB ru rvri I 35 5U HWI ou PUR5Ud UUT TO THE REGL.aw="5 OF 10 CFR 5: (Check erse or ynors) (11) 20.2201(b) 20.2203(a)(2)(v) g 50.73le)(2)t4 50.73(e)(2)(vill) j r____ 20.2203(eH1)- 20.2203(e)(3}H 50.7318)(2)(I1) DU.73(el(2)(x) 1.EVEL (101 . 0 -

20.2203(enzio) 20.2203(a)(3)ni) 60.73(el(2)(iii) 73.7i

,, ' -" - -- ~g 20.2203(a)(2)nt) 20.2203(a)(4) 50.73(sH2)(ivl oTHER

, [ 6) 50.35(c)(1) X 'o 7't'"2)iv) g.;<ggge.i (

20.2203(e)(2)Uvl 50.35(c)(2) 60.73(eH2)(vii)

)

Lii.,essnat CONTACT FOR THIS LER (12) ,

rewnwss muMoum unswo aree Geom I ame Ames M. Peachel, Regulatory Compliance Manager (603) 773-7194 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCinscD IN THIS MerORT (131 CAust sysTam coMPontNT MANUFAGluMtM M E CAV5E ETynM COMPQNENT MAhuFAcTUREM n w g.E i ': l l

~

J X EK RLY W120 Y

?

I .UPPLElWuua l AL rieruru EAru bi sp (14) tArcu cu MONTM DAY YtAR 8U '8 Yam V NO

- (tf yes, complete EXPECTED SusMIS$10N DATE). O As iTRACT (Umit to 1400 spaces,i.e., opproWrnately 15 alngle spaced typewritten Hnes) (15)

On March 31,1999 at 1100, during the sixth refueling outage, North Atlantic Energy Service Corporation (North  !

Atlantic) determined that the Train B Emergency Diesel Generator (EDG) may not have been operable during portions  !

cf the previous operating cycle. Specifically, during 18 month EDG testing on. March 29,1999, it was determined that  !

an AR relay associated with the Train B EDG Emergency Power Sequencer (EPS) was incapable of opening the breaker l to the Unit Auxiliary Transformer (UAT). His could have prevented the. Train B EDG from powering the emergency )

bus if called upon to do so. Additional testing on March 30,1999, reveal.ed that another AR relay associated with the )

I Train B EDG EPS was incapable of starting a Containment Building Spray (CBS) pump. This would have prevented the Train B CBS pump from automatically starting if called upon to do so.

This event was caused by a combination of two factors; formation of corrosion products on the relay contacts and other surfaces resulting from age related degradation of the relays' molded neoprene cover gaskets and improper relay calibration settings. De AR relay internals and covers in bod) trains of the EDG EPS will be replaced with new units prior to startup from the current refueling outage. The procedure utilized for testing the AR relays has been revised to clarify techniques and acceptance criteria. The AR relays in the EDG EPS will be periodically inspected for signs of corrosion and sanket degradation, unc Pom see a+es) b f'

JAN-23-1900 15:46 ~ -USNRC REGION I SEABROOK '603 474 9018 P.05

)NIC PoMI s98A U.s. NUCLEAR REGULaTcRY cCMMissioN s&ss

.. LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION i PaCIUTY NaME (1) DOCKET NUMBER (2) LER NUMBER (S) PAGE (31 05000443 M uwamAL MtVWW WMBER WMBER 2 of 8 Seabrook Station 99 - 001 - 00 TaKT #/mene space 4 requirsaE use sablWone/ copies of M9C Fam,36sAJ (17)

1. Description of Event

'On March 29,.1999, at 1254 EST, during the' sixth refueling outage, the Train B Emergency Diesel Generator [EK] failed its 18 month loss of power test conducted in accordance with Technical Specification (TS) 4.8.1.1.2.f.4. The test failure occurred when an Emergency Power Sequencer (EPS)

(EK) Westinghouse Type AR high speed auxiliary relay failed to function properly. The subject relay's (K85) function is to open the 4160 volt circuit breaker connecting the Unit Auxiliary Transformer (UAT)[EA] to the E6 emergency bus [EB]. As a result, the Train B EDO started but its output breaker did not close. This prevented the EDG from powering the emergency bus during the testing.

After relay K85 was replaced, the Train B EDG loss of power test was again conducted on March 30, 1999 at 0834 EST, and another EPS Westinghouse type AR output relay failed to function properly. De subject relay (K77) starts the Train B Containment Building Spray (CBS)[BE] pump (CBS-P-9B). While i the emergency bus was successfully powered, the K77 relay failure prevented the Train B CBS pump from autarna&nUy starting. Although the CBS pump would not normally start on a loss of power, the test simulated a containment spray signal to verify the sequencing for the CBS pump start.

On March 31,1999, at 1100 EST, North Atlantic Energy Service Corporation (North Atlantic) determined that the Train B EDO may not have been operable during portions of the previous operating cycle (June l 1997 - March 1999). This conclusion was reached when information became available that the aforementioned relay failures most likely occurred sometime before the loss of power test was conducted. (

Since it is possible that the Train B EDG had been inoperable at times when the Train A EDG was also inoperable for maintenance or testing as allowed by the TS, it was concluded that this represented a i

condition that alone could have prevented the fulfillment of the safety function of structures, systems, or components that are needed to mitigate the consequences of an accident. North Atlantic ieyoited this condition to the NRC on March 31,1999 at 1307 EST, pursuant to 10 CFR 50.72(b)(2)(iii).

He potential inoperability of the Train B EDG for periods longer that the TS allowed outage time (72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />) and possibly concurrent with the TS allowed inoperability of the Train A EDG as a result of maintenance or testing constitutes a condition prohibited by the TS and is also reportable pursuant to 10 CFR 50.73(a)(2)(i). ,

H. Cause of Event North Atlantic has determined that this condition was caused by a combm~ ation of two factors: formation of corrosion products on the relay contacts and other surfaces and improper relay calibration settings.

Some of the AR relays in the EPS, including K85 and K77, exhibited higher than normal resistance across their silver contacts as a result of a silver sulfide film. The silver sulfide film was caused by the release of compounds from the age-related degradation of the relays' molded neoprene cover gasket. Over time, the

=c ro. ...

1

E JAN-23-1900 15:47 'USNRC REGION I SEABROOK 603 474 9018 P.06 NRC PoRM 36aa U.S. NUCLEAR REGULATORY CoMMisSloN 14 08).

. LICENSEE EVENT REPORT (LER) l I

TEXT CONTINUATION FACKJTY NAMa (1) DOCKET NUMSER (2) LER NUMBER f61 PAGE (3)

Q$Q g YLAR SEQUENTIAL MtVl51UN NUMBER NUMBER Seabrook Station 3 of 8 99 -- 001 - 00 TsxT pf more spece in readed. we cadelonel copine of AMC form 366A) (17) gaskets released compounds such as sulfuric acid, hydrochloric acid, and other sulfur bearing compounds.

These compounds attacked the relays' silver contacts and caused the formation of a silver sulfide film.

These co-amm a n also caused corrosion on other metallic relay parts. For the K85 relay, the silver sulfide film in conjunction with low contact pressure caused the relay to fail. For the K77 relay, it is believed that the contacts would not open due to foreign debris and the relay not being calibrated properly.

In m:st cases, the electrical resistance of the silver sulfide film was overcome by either the voltage applied across the contacts or sufficient contact pressure and the relays performed properly. However, if the relay 1 was not optimally calibrated such that it exhibited more than minimal deviation from the relay setup acceptana criteria, then it was possible that this, in conjunction with the sulfide film, created a condition where the relay may not function properly.

As stated above, some of the relays were not optimally calibrated. This was caused by inadequate calibration by the relay manufacturer. A contributing cause was'the lack of adequate acceptance testing to verify all critical characteristics by Automation Industries, Inc., Vitro Laboratories Division, the manufacturer of the EPS who qualified the relays and North Atlantic upon receipt of the EPS.

N:twithmading, the AR relays in the Train B EDG EPS which were replaced during the previous j refueling outage were verified to be operable following maintenance testing via successful EDO testing during that outage Hence, improper relay calibration alone did not adversely affect relay operability. )

i

m. Analvois of Event The AR relay failures did not result in any adverse safety consequences since offsite power was always available during the last operating cycle and the Train B EDG was not called upon to respond to an actual  ;

1:ss cf offsite power. However, this condition has safety significance since the Train B EDG may not j i

have been operable during portions of the previous operating cycle for periods of time longer than the TS

, all3wed outage time and during periods when the Train A EDG may have been removed from service for maintenance or testing.

North Atlantic has been unable to conclusively determine when during the last operating cycle the two AR relays Mme inoperable. The thirteen AR relays in the Train B EDG EPS were replaced with available sparesjust prior to the last operating cycle during the fifth refueling outage which was completed in June l 1997. These spares were the same age as those originally installed in the EDG EPS and they had been in j storage since plant construction. The relay contacts were inspected and cleaned if necessary, prior to installation. The operability of the relays was verified during surveillance testing; conducted during the fifth refueling outage. North Atlantic believes that sulfide deposition on the contars occurred over time.

During the last operating cycle the Train A EDG was inoperable for maintenance and testing for a total of approximately 7.5 days; Independent of this, the Train A emergency bus E5 was inoperable for unc rom seem.esi

JAN-23-1900 15:48 USNRC REGION I SEABROOK 603 474 9018 P.07

, NRc FORM aGSA U.s. NUCLEAR RE1ULAToRY Commission i4.ess -

UCENSEE EVENT REPORT (LER)

TEXT CONTINUATION FAcaJTY NAME (1) DOCKET NUMBER (2) LER NUMBER 16) PAGE (3) 0600o443 vtAR 5tGUkNIIAL REVl5f0N NuusER NUMBER Seabrook Station 4 of 8 99 - 001 -- 00 TEKT Wmere noeen k n%ef one edcNicnot ceplee of AMC Fem,366N 07) o approximately 0.54 day. Similarly, the Train A CBS pump was inoperable for a total of approximately 6.25 days during the last cycle. Based on this,,both trains of EDGs and both trains of CBS would have been inoperable concurrently for o'nly a relatively short period of time during the last cycle.

North Atlantic believes'that the AR relay failures would not have caused any adverse safety consequences during a loss of offsite power event while at power operation even if the Train A EDG was unavailable. In this scenario, the Train B EDG would have automatically started but the K85 AR relay failure would have prevented it from automatically powering the emergency bus in response to the loss of offsite power. This would have resulted in a los of power to the Station. However, proceduralized operator action would

.have directed- prompt restcration c,f power to the emergency bus. When in Modes 1 - 4, Step 3 of Emergency Procedure E-0, "Reacter Trip or Safety Injection," verifies power to the emergency busses and restores power if necessary. At this point in E-0, it is likely that, based on information available on the main control board in the Control Room, operators would recognize that the UAT breaker was closed and open it from the Control Room. Based upon observations of operating crews during simulator training scenarios regardmg Imv long it takes to complete steps in the emergency procedures, it is estimated that ,

the UAT breaker would be opened in this scenario within approximately 30 seconds. l l

Continuing with this scenario, if power was not restored by step 3 of E-0, then the operators would transition to procedure ECA-0.0, " Loss of All AC Power." Step 5.a of ECA-0.0 requires the operators to verify that the UAT and Reserve Auxiliary Transformer (RAT) [EA] supply breakers are open and if w-aa y, to open them. Following this, operators verify that the EDO is running and that the EPS s

automatically actuates.and the EDG loads properly, which results in the restoration of power to the emergency bus. It is estimated based on this sequence of steps that the UAT breaker could have been cpened within approximately one minute forty-five seconds of event initiation which would have allowed loads to be automatically sequenced onto the emergency bus at five second intervals over the next two minutes based on a preestablished priority. .

This $m*d period of time to restore power is insignificant since Seabrook Station is a four-hour coping plant to satisfy the Station Blackout regtirements of 10 CFR 50.63. During the four-hour coping period, the plant relies only on the Station batteries (EJ] as a source of electrical power and no adverse safety consequences would be experienc.ed.

s NRC FORM 306A 14 95)

JAN-23-1900 15:49 USNRC REGION ! SEABROOK 603 474 9018 P.00 NecFonu seeA u.s. NUCLEAR REGULATORY CoMM1851oM wesr >

. LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACIUTY NAME (il DOCKET NUMBER (2l LER NUMBER (61 PAGE is)

YEAR SEQUENTIAL REVl51DN 06000443 N W BER NW8ER Seabrook Station 5 of 8 99 -- 001 -- 00 TEXT #f more Jpece Ar meuked use asWonel copies e/ AMc Arm 366N (17)

The most limiting hypothetical accident scenario (beyond design basis) for the relay failures involves power operation with a simultaneous large break loss of coolant accident (LOCA) with a resultant high pressure in the containment building (NH] requiring the initiation of CBS and a loss of offsite power at a time when the Train A EDG was inoperable. This is a very unlikely' event with a probability of 2.9 E-09.

Similar to the loss of power scenario without the LOCA, the Train B EDO would have automatically started but the K85 AR relay failure would have prevented it from automatically powering the emergency bus in response to the loss of offsite power. This would result in a loss of power to the Station and a loss cf emergency core cooling and CBS until power is restored. However, when the bus was manually powered from the Train B EDG by the operators, the K77 relay failure would have prevented the Train B ,

CBS pump from sequencing onto the bus and automatically starting. Irrespective of this, it is reasonable  !

to expect that operator action would have started a CBS pump.

Had the operators stayed in E-0, step 14 would direct them to manually actuate CBS from the main control board in the Control Room. If the operators had previously transitioned to ECA 0.0, the operators would transition to procedure FR-Z.1 " Response to High Containment Pressure," upon restoring power to the emergency bus. Step 3.b of FR-Z.1 directs operators to manually start the CBS pumps if they are not already running. It is estimated based on this sequence of steps for either staying in E-0, or transitioning to ECA 0.0, that the operators would have attempted starting the CBS pump CBS-P-9B within less than approximately five minutes from initiation of the accident.

Hswever, it is also possible that the operators would not have been successful at starting the CBS pump since in this' scenario, the circuit design would require the pump's control switch to be placed in either "stop" or " pull-to-lock" before. the pump could be successfully started when the control switch is placed in l

run. If the pump was not started at this time, operators would likely dispatch an electrician to check the pump's circuit breaker, before which the pump's control switch would likely have been placed in " pull-to-lock." For the purpose of this scenario, it is estima+ed that the troubleshooting would be completed such that the pump could have been successfully started within approximately 10-15 minutes from the initiation  ;

ef the event.

. North Atlantic evaluated the most limiting accident scenario described above by running sensitivity cases i

with a semi-best estimmte Seabrook Station specific non 10 CFR 50 Appendix K ECCS model. Consistent with the above e*+i=+ d operator response times, this modeling considered power restoration to the emergency core cooling pumps such that pumps would be running and up to ' speed within an estimated  ;

two minutes three wh. This would result in an increase in the peak cladding temperature (PCT) by approximately 5 to 200 degrees Fahrenheit depending on whether operators opened the UAT breaker at 30 seconds or one minute forty-five seconds. In either case, the PCT remains below 2200 degrees Fahrenheit.

Hence, under the hypothetical scenario and assumed manual actions described above, this condition would not adversely affect fuel integrity nor increase the radiological consequences of an accident. ,

unc rom seu won

'~

[ ' ' ' JAN-23-1900 .15:50 USNRC REGION I SEABROOK 603 474 9018 P.09

?*

mRc Fonu sesa U.S. NUCLEAR REGULATORY CoMMIS$loN H.esi

- LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACIUTY NAIAE til DOCKET NUMSER (2) LER NUMBER (4) PAGE(2 YEAR 5EQUEN wM. REVI5 ION 05000443 N W BER NW9ER g gg g Seabrook Station 99 - 001 -- 00 T1Dit tarme,e pace A, reeke4 see eMalonel owles ofIMC form 369) l17)

If the CBS pump was successfully started within five minutes ofinitation of the event, then containment building pressures would remain less than the design basis value of 52 psig. However, the lack of CBS for a total of approximately ten minutes from the initiation of the accident would have allowed containment building intamal pressure to increase to approximately 53 psig. Ifit took longer to establish CBS, such as 15 minutes from initation of the event, then containment pressure could reach approximately 55 psig.

. Both of these values are above 52 psig but below the point where the containment building would be expected to fail. Hence, under the hypothetical scenario and assumed manual actions described above, Nath Atlantic believes that containment building integrity would not have been compromised as a result cf this condition.

It should also be notedthat some events that result in a loss ofpower also result in a direct trip of the UAT circuit breaker by protective relays. Examples include a 345kV bus fault or a UAT or Generator Step-up Transfonner (GSU) [EL) failure. For these events, the K85 relay function to trip the UAT would not be named and hence, would not have prevented the EDG from automatically supplying power to the emergency bus.

While not the most limiting hypothetical accident scenario, North Atlantic also evaluated the potential affect of the AR relay failures during the shutdown modes. The K85 relay failure would have prevented shutdown cooling systems from removing heat from the Reactor Coolant System (RCS)[AB) if a loss of power event occurred while in Modes 5 snd 6 when the Train A EDG was also inoperable. In response, cperators would implement procedure OS1246.01 " Loss of Offsite Power - Plant Shutdown." The first

. step of this procedure directs operators to restore power to any emergency bus by verifying that the UAT and RAT supply breakers are open and if necessary, to open them. Following this, operators verify that the EDG is running and that the EPS actuates and the EDG loads properly, which results in the restoration cf p'ower to the emergency bus. These actions would be completed in less than approximately two minutes such that shutdown cooling would be restored well before the onset of any adverse consequences.

In conclusion, North Atlantic believes that for the hypothetical accident scenarios described above, the AR mhy failures would not have compromised the integrity of the fuel nor the containment building and therefore would not have increased the radiological consequences of an accident.

IV. Corrective Action As an interim corrective action, the thirteen AR relays in the Train A EPS and four AR relays in the Train B EPS were replaced with available spares and EDG testing was satisfactorily completed. The contacts for the remaining nine AR relays in the Train B EPS were inspected and cleaned as necessary. The relays that had been in place in the Train A EDG EPS were inspected and while some showed evidence of higher NRC PORM 388A 44 88)

JAN-23-1900 15:50 USNRC REGION I SEABROOK 603 474 9018 P.10 NRcPoRMassA U.s. NUClf.AR REGULATORY CoMMISoloN (4.es) .

.. LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION LER NUMBER (6) PAoE (3) I FACsfrY NAME (1) DOCKET NUMBER (2) 06000443 nan nuveNTIAL newmuN l Seebrook Station W"" " # 8E8 7 of 8 99 - 001 - 00 TEXT Wmore spece Ar rogsdred, we seloWons/ copies e/N#c Fomi 3dsA/ (171 than normal contact resistance and the presence of some corrosion products, it was concluded that they would have functioned properly.

As corrective actions to prevent recurrence, the AR relay intemals and covers in.both the Train A and Train B EDG EPS's will be replaced with new units prior to startup from the current refueling outage.

The avLdag relay cases will be utilized, but they will be cleaned to remove any corrosion residue. The replacement relays were manufactured by ABB in April 1999 specifically for Seabrook Station. The new relays utilize a cover gasket made of extruded ~ neoprene, as opposed to molded neoprene, which was used in the original relays that failed. Additionally, these relays will be confirmed to be properly calibrated by the vendor before installation.

. North Atlantic has also revised the procedure utilized for testing the AR relays to clarify techniques and ae~panca criteria to incorporate the lessons learned from this event and to visually inspect the AR relays in the EDG EPS for signs of corrosion and gasket degradation. This inspection will supplement the 1 Technical Specification required EDG surveillance testing.

l Ferty-six similar type AR relays are utilized at Seabrook Station for non-safety related electric distribution system protective relaying. Some of these relays have also exhibited signs of corrosion although this has not prevented them from functioning properly. These relays are functionally tested on a periodic basis and f:r the most part, are backed up by redundant relays, or relays of a different type. North Atlantic will also peri ~Heally v3ually' inspect these type AR relays for corrosion and gasket degradation, burnish their contacts and replace their cover gaskets over a period of time.

V. Additional information The phenomenon of silver sulfide film growth on stored satellite electrical components was researched l and daeama*A_ in a report developed for NASA on- March 25,1988, " Sulfide Corrosion of Silver Contacts During Satellite Storage," R. Bauer, Chemisty and Physics Laboratory, lhe Aerospace Cory Gon,ReportNumber AD-A196217; This research addressed sulfide Sim growth on silver, growth machanisms, electrical properties, and techniques for reducing the potential for sulfide growth.

gig})ler Events This is the first event at Seabrook Station involving the inoperability of an EDG as a result of Westinghouse AR relay failures. -

NRC PoRM 366A 14 95)

JAN-23-1900 15* E USNRC REGION I SEABROOK. 603 474 9018 P.11

,NRC PoRM a80A U.s NUCLEAR REoVLAToRY CoMMISSloN loosi

!.. LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION DOCKET NUMBER (2) LER NUMBER (6) PAGE (31 PACRJrY NAME lil 06000443 YEAR 5tOUENTIAL REVI5 ION WMBER NUMBER g of g Seabrook Station 99 - 007 - 00 Terr pf mom space Ar mpdw4 we echtddnel cap /es of NRC Fomp 36dAJ (17)

Manufacturer Date AR Relays: Westinghouse-four pole auxiliary type Direct Current (DC) AR relays designed for high speed circuit breaker control. The following two styles of AR relays were used in the EDG EPS: 606B017A09A and 606B017A15A. These relays were manufactured between 1979 and 1982. The AR relays are currently being manufactured by Asea Brown Boveri (ABB) in Coral Springs, FL.

The AR relays that were in the EDG EPS were originally supplied by Westinghouse as commercial relays to Automation Industries, Inc.' Vitro Laboratories Division, who qualified them and installed them in the EPS.

t 3

NRC FOfN 300A (496F