ML20236N333

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SER Re Request for Interpretation of EDG TS 4.8.1.1.2.e for Farley Nuclear Plant,Units 1 & 2
ML20236N333
Person / Time
Site: Farley  Southern Nuclear icon.png
Issue date: 08/21/1997
From:
NRC (Affiliation Not Assigned)
To:
Shared Package
ML20236J990 List: ... further results
References
FOIA-98-155 NUDOCS 9807150092
Download: ML20236N333 (2)
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BAffTY EYAlilAT1DN BY THE OFFICE OF NUCLEAR REACTOR REGULATION R1Quf.AI FOR RKTEAPAf TAT 10N OF EMERGENCY DIEREL GFMEBAIDE TECHNICAL SPECIFICATION 4_R.1.1.22.

FARLEY NUCLEAR PLANT. UNfTS 1 AND 2 DOCKET NOR. 60448 AND 50- 344 MCEDhDIBG h as tener of May 22,19g7. Sowhern Ncioar Operahng Comparty (boensee) requested an enorpretaban of the >chncal Mm (78) concomme the load repcbon testeg for the two throd energency deoel generssors (EDGs).12A and IC. at Farley Nuclear Plant (Farley).

Unas 1 ml 2 Portners portone of each ins TS Survesence Requrement (SR) 4.8.1.1.2.e reeers moee shared EDGs to menstand a 1200 2400 kW load repcbon every Ave years. The teenmee hee been performme me edycs SR by shgrung one of the shared EDGs (EDG 12A) to uns 1. mi anyung me amor EDO (EDO 1C) to Und 2 Sm me leed repocton lost a pertermed to verdy the operetzer:y of the EDG voltage regulator WW governor. me teel does not depend on the loads to whch these unas are connected. The I aconeee careends mat toesn0 com EDGs 12A and 1C on a per und TS basis would represent seepers and eassessee noseng of the EDGs and a not necessary. Thus, the beansee r archmed shat as curvors noseng memod sabshes the TS SR 4 8.1.1.2 e provtsson for the anaos EDGs at Fartey However, me resadent nspector reviewed the bconsee's evaluation and Gearood men me teensee's conctusaon, and requested NRR to interpret l TS$448112e E.

OfALM&IElf There are 6,e eeeef generosors tot ewo unas at Farley. Tram 8 of the two unas has one large (4015 kW) em EDO tot each uru (desagnated as 18 and 28) As the rest of the desel

} ponerators. one type 4015 kW (12A) and two smas 2450 kW (1C and 2C), are shared by both anos are are provided men yterlocks to prevert them Irom suppfying power to Unit 1 and Unrt 2

! esumAansoimfy Tee EDGs (12A and IC) among de three shared chesels are serving Train A

- of eeer urus, artes deoef 2C a mM for stahon tdackcut everta and suppies power to the F

B ran of eeer urns Sence she 8 ram has no shared EDGs the interpretation of TS SR 4 81 12 e apphoe to the shared EDGs e the A trari.

Currere 54 4 81 12 e of me TS at Fartey for Unas 1 and 2 requres that:

At Isaat once per 5 years, on a staggered base, by ventyng that the emergency eseef generator can repoca a load of 1200 2400 kW without tnoping. The ernergency eeeef generseer output treakarts) must remam closed such that the

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_ ATTACHMENT r

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9807150092 980624 PDR FOIA UNNERST98 ,155 PDR

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RAFETY EVALUATION RY TNf OFFICE OF NUCLEAM REACTOR R*O_QLATION REQUE.Af 7QM INTEAMtf TAT)ON OF EMERGENCY Dif SEL .GENEAATOR TECHNICAL RPECiflCATION LR111e .

FAALEY NUCLEAR PLANT. UNITR 1 AND 2 DOCKETNOLA0448AND50344 M

Wi es tueer of May 22.1997. So Ahom Nudear Operaeng Company (hcensee) requested an ensrpresamen of me Mcfrucat apardem (TS) concenung the load resecuon testeg for the two enwed emergency seeef generasors (EDGs).12A and IC, at Farley Nucaser Plant (Fariey).

Lhes I rd 2 Portners portons of each ure TS Survesence Requrement (SR) 4.8.1.1.2.e reeers moes enered EDGs to wehetand a 1200 2400 kWload rerecuon every Ave years. The tsensee has boon perlormng me subpect SR by shgnng one of the shared EDGs (EDG 12A) to tw 1. rd asynng me omer EDO (EDO 1C) to Una 2 Sece me teed repecten test a periormed to verWy the opersbesty of the EDG vonage regulator ww govemer. me test does not depend on the loads to wtuch these unas are connected. The aseeee cornenes that tesang bom EDGE 12A and 1C on a per und TS basis would represent sothedere rid secesaw locang of she EDGs and a not necesswy Thus, the beensee caractuesd that as cwrert beseng method satsnes the TS SR 4 8.1.1.2 e provisen for the shared EDGs at Fartey However, she rewdent repector reviewed the beensee's evaluation and esarsed man she aconsee's condusen, and requested NRR to interpret TS SR 4 8112 e EX&LM&ICid There we eve seeef ponerasors for two unas at Farley. Tram B of the two units has one large (4075 kW) em EDO for each una (desagnated as 18 and 28) As the rest of the desel ponerammL one large 4075 kW (12A) and two smas 2850 kW (1C and 2C), are shared by both wies and we provided weh stortocks to prevent them from supplyng power to Unit 1 and Unrt 2 asnumaneoussy Too EDGs (12A and 1C) among We three shared desels are serving Train A of emer wut. utdo esmei 2C e -M for stauon War *rd events and supphes power to the 5 ten of esher wit Sece the 8 tan has no shared EDGs the interpretation of TS SR 4 81 12 e appees to she shared EDGs a the A traet Cwrort SR 4 81 12 e of she 78 at Farley for Unas 1 and 2 requres that:

At Isaet oas per 5 years, on a staggered bass, by wentyng that the emergency eseef genersect can repect a load of 1200-2400 kW unthout tnoping. The emergency e***l genersoor output breaker (s) must remam c$osed such that the ATTACHMENT 9807150092 980624 PDR FOIA UNNERST98 ,155 PDR

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emergency diesel generator is connected to at least one emergency bus. Verify that all fuses and breakers on the energized emergency bus (es) are not tripped.

The generator voltage shall remain within 3330 and 4990 volts during and following the load rejection.

Each EDG is provided with an engine overspeed trip to prevent damage to the engine.

Recovery from the transient caused by the loss of a large load could cause the diesel engine to overspeed, which,if the overspeed is excessive, might result in a trip of the engine. Therefore.

TS SR 4.8.1.12.e'(i.e., the load rejection test)is prescribed to verify the ability of the EDG voltage regulator and govemor to respond such that voltage and frequency transients continue to remain within acceptable limits and the EDG does not trip during a load rejection.

Although EDGs 12A and 1C are designed to be shared between two units and each unit maintains a separate TS at Farley, the licensee has been performing the subject SR once per five years by stigning EDG 12A to a Unit 1 emergency bus and aligning EDG 1C to a Unit 2 emergency bus. The NRC inspector reviewed the above mentioned SR provision and questioned whether the shared EDGs should be tested for each unit twice in five years.

The licensee took the position that it is not necessary for each shared EDG to be aligned to each unit for testing for the following reasons:

1) The load rejection test is conducted to validate the EDG function by verifying the ability of the voltage regulator or govemor to maintain the load within acceptable limits during a load rejection. Thus, the test results depend on the equipment within the EDGs themselves, not on the EDG loads used for the test, if there is a problem with the EDG voltage regulator or govemor, it would be evident regardless of the loads that are connected to it or which unit the load came from.
2) When the staff granted the load rejection testing frequency from every 18 months to every five years as shown in the current TS SR 4.8.1.1.2.e. the testing was intended for each EDG on an EDG by EDG basis, not on a unit by unit basis.
3) If the shared EDGs are required to be tested on a per unit basis, the (shared) EDGs in i the A train would be performing the load rejection test twice as often as the (dedicated)

EDGs in the B train.

4) Having five diesel generators that have either an automatic or manual capability to load one of the two safety traias represents much greater flexibility than having four dedicated EDGs installed in a two trains as shown in the NRC's Standard TS. Thus, in j terms of reduced surveillance and testing requirements for EDGs, credit can be given to

! the Farley TS in order to avoid redundant testings.

l l Since the purpose of this surveillance is to demonstrate that the voltags regulator and govemor l In each EDG are performing correctly, TS SR 4.8.1.1.2.e for Units 1 and 2 at Farley tests the EDG themselves, not the EDG loads. Therefore, the staff concurs with ths licensee's interpretation that the testing requirement for the shared EDGs (12A and 10) in TS 4.8.1.1.2.e is satisfied by aligning these EDGs to either Unit 1 or Unit 2 independently, as long as tneir operability is confirmed once per five years. Subsequently, the licensee has submitted a TS amendment request to clanfy SR 4.8.1.1.2.e for the shared EDGs, which the staff is currently reviewing.

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