U-601879, Requests Waiver of Compliance from Tech Spec Limiting Condition for Operation Re Standby Emergency Diesel Generator 1B,to Permit Addl Time to Effect Repairs Re Discovery of microbiologically-induced Corrosion in Jacket

Requests Waiver of Compliance from Tech Spec Limiting Condition for Operation Re Standby Emergency Diesel Generator 1B,to Permit Addl Time to Effect Repairs Re Discovery of microbiologically-induced Corrosion in Jacket

ML20082S643
Person / Time
Site:	Clinton
Issue date:	09/06/1991
From:	Jamila Perry ILLINOIS POWER CO.
To:	Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20082S644	List: ML20082S651 U-601879, Requests Waiver of Compliance from Tech Spec Limiting Condition for Operation Re Standby Emergency Diesel Generator 1B,to Permit Addl Time to Effect Repairs Re Discovery of microbiologically-induced Corrosion in Jacket
References
U-601879, NUDOCS 9109170228
Download: ML20082S643 (9)

Text

., _ _ - _ . . _ .

ilhnois Ponet Company

• • Chnion Power Station l

• P O Don 678 +

Chn10n, IL 61727  !

- Tel 217 935MP6 J. Stephen Perry Woe Preudent ILLIpleDI!E NMR "~6' 87*

L4 7-91 ( 09 -06 ) -LP 8E.100a I

September 6, 1991 10CFR50.91(a) (5) l 10CFR50.91 t i

l Docket No. 50-461  !

Mr. A. B. Davis  ;

Regional Administrator .

Region III  !

U.S. Nuclear Regulatory Commission  ;

799 Roosevelt Road  :

Glon Ellyn, Illinois 60137

(

SUBJECT:

Request for Waiver of Compliance Regarding Technical Specification Limiting Condition for i operation Related to Standby Emergency Diesel Generator 1B

Dear Mr. Davis:

Events have occurred at Clinton Power Station (CPS) which requiro your prompt attention as Illinois Power  !

(IP) requests a waiver of compliance regarding the Technical Specification Limiting condition for operation l specified for the Division II Standby Emergency Diesel l Generator (DG1B). IP specifically requests that the l current limit of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for the allowed out-of-service time specified in Action "b" of CPS Technical Specification 3.8.1.1 be waived, as IP desires additional time to offect repairs in response .o the discovery of microbiologically induced corrosion (MIC) in the jacket l

water heat exchanger for the 12-cylinder engine of DG1B.

In order to implement a complete and thorough (short-term) fix to the MIC problem for DG1B, IP  ;

currently plans to replace both jacket water heat exchangers associated with DG1B. Therefore, IP requests l

that this waiver of compliance remain in effect until both jacket water heat exchangers for DG1B are replaced and operability of DG1B has been restored and verified.

IP estimates that, despite IP's continuous efforts to complete repair of DG1B, this work may require additional time beyond the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> allowed by the CPS Technical Specifications. Therefore, IP reqtests that Ai v \

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DG1D be allowed to remain inoperable until 2050 hours0.0237 days <br />0.569 hours <br />0.00339 weeks <br />7.80025e-4 months <br /> on ,

f September 9, 1991, for a total of four days (i.e., 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> beyond the 72-hour allowed out-of-service timo ,

i specified in tho Technical Specification Action Statomont). If this request is.not approved, CPS must be i in at Itact a Hot Shutdown condition by 0850 hours0.00984 days <br />0.236 hours <br />0.00141 weeks <br />3.23425e-4 months <br /> on l September-9, 1991. i A more detailed description of thn condition, including the circumstancos surrounding the event, an ovaluation of the safety significance, justification for  :

i this request, and a discussion of why this roquest does not involvo a significant hazards consideration is provided in Attachmont 1 of this lotter. Copios of the rolovant portions of CPS Technical Specification 3.8.1.1 are provided in Attachment 2 for reference.

IP has reviewed this request against.the critoria of 10CFR51.22 for categorical exclusion from environmental impact considerations. The roquest does not involvo a significant hazards consideration, or significantly increaso the amounts or change the types of offluents that may be released offsito, nor doos it significantly

-increase individual or cumulativo occupational radiation oxposures. Based on the foregoing, IP concludes that the proposed request moots the critoria given in 10CFR51.22 (c) (9) for a categorical exclusion-from the requiremont for an Environmental Impact Statement and thoroforo does not involve irreversiblo environmental consequences.

This request has boon reviewed and approved by the CPS Facility Review Group.

Sincoroly,

[

h S. Perry Vice President DAS/alh Attachments cc: NRC Clinton Licensino Project Manager NRC Resident Offico Illinois Department of Nuclear Safety NRC Document Control Desk i

i 1

' ,' Attachment I to U-601879

. Pago 1 of 7 Ilencription of Condition /Reangp for Reqqggt During normal shift roundo at approximately 2030 hourn on September 4, 1991, a plant operator dincovered that the jacket cooling water expansion tank on the 12-cylinder orgine for the Division II diocol generator (DG1D) at Clinton Power Station (CPS) was overflowing into tho floor drain at a rato of approximately one gallon /minuto.

(A heat exchanger in provided for each of the two tandom enginen (ono 16-cylinder and ono 12-cylinder) annociated with DG1D.) From earlier experienco, Illinclu Power (IP) suppocted that this may be caused by nervice water leaking through the diocol gonorator heat exchangor tuben into the jacket water cooling system. Although thin condition would not provont the DG from performing its cafety function (since the diosol can function with direct service water flow into the engino water jacket),

DG1D wan-romoved from nervico at 2050 hourn on September 5, 1991 for investigation and repair. Subcoquent inopoction revealed the prononco of microbiologically induced corrosion (MIC) which in believod to bo the cause of the tubo leakago.

MIC was first identiflod in the DG heat oxchangora at CPS in 1989 as IP was developing and implomonting its responco to Generic Lottor 09-13 and the associated supplomont.* As an immodiato correctivo action, cleaning and closed loop chemical treatment of the DGlu hoat exchangoro woro performed during the third planned outago (PO-3) at CPS (February 1990) to temporarily arront the MIC problom for DG1D. Rotubing of tho heat exchangora for the Division I diocol generator (DGIA) and oddy-current testing of the tubos in the heat exchangora for the Division III diesel generator (DG1C) wore also completed during Po-3. Subsequent to Po-3, IP chemically treated the Division II norvicu water syntom twico on an open-loop basic to provent further growth of MIC.

Howevor, IP replaced the tubon in the heat exchangers for DG1D in July 1990 following diccovery of a nimilar tubo leak (roference IP letter U-601696 dated June 22. 1990).

With the discovery of further MIC attack in the DG1D heat exchangor, it now appears that the current treatment schemo has not boon as offectivo ao IP originally bolloved and further ovaluation in required.

The oporability requiremento (during operational Conditions 1,2, and 3) for the omorgency standby diocol generators, including the actions to be taken if one (or more) 10 inoperablo, are speciflod in CPS Technical Specification 3.8.1.1. (Sco Attachment 2 of thic submittal.) Action "b" requiron that with either diocol generator-1A or 1D inoperablo, oporability of the required AC offsito sources must be demonstrated,

• Roforenco: IP Lottor U-601574 dated January 29, 1990

Attachment I to U-601879

. Pago 2 of 7 operability of the remaining oporablo diosol generators must bo demonstrated (unless the DG boca.no inoporablo solely duo to proplanned proventivo maintenanco or testing), and the inoperablo DG must be rostored to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. If the inoporablo DG cannot be restored within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, the plant must be brought to a Hot Shutdown condition within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and to a cold Shutdown condition within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Based on visual inspection of the tubos within the heat exchangor associated with the 12-cylindor engine of DG1B and previous experience with HIC at CPS, IP datormined that replacement of the heat exchanger was required.

Based on the sirallar service environment and operating history of the DG1B heat exchangers, IP determined that tho heat exchanger associated with the 16-cylinder engine of-DG1D should also be replaced. Sinco the heat exchangers are being replaced concurrently, this decision will not significantly alter the total timo required to complete the replacomant. Although replaceront heat oxchangers are currently availabic on sito and IP in working on a' continuous basis to comploto the replacement, the replacement and subsequent rotestw may not be able to be completed before the 72-hour time limit expironiat 2050 hours0.0237 days <br />0.569 hours <br />0.00339 weeks <br />7.80025e-4 months <br /> on September 8, 1991. It is currently estimated that up to four days may be nooded to complete replacement of the heat exchangers, verify adequato service water system flow through the replacement heat exchangers, and complete testing required to rever'efy operability of_DG18.

Ilescrintion/ Sequence of Work _to be Performed As indicated above, the work plan for replacement of the heat exchangers for DGlB is such that both heat exchangers will be replaced concurrently. Both replacement heat exchangers are currently onsito. After installation of the replacement heat exchangers, pressure testing and service water flow verification will be required, followed by performance of a post-maintenanco surveillance test. IP currently estimates that all of the above may take up to an additional 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> beyond tho-out-of-sorvice timo normally allowed by the CPS Technical Specifications.

Justification for Pronosed Roauest The IP electrical system design providos a diversity of power supplies. This request for waiver of complianco is L justified partially on this diversity. The 138-k

! offsito power system provides power to the station by one throo-terminal transmission line. This lino connects the station to the IP grid at the south Bloomington and Clinton Route 54 Substations. Electrical power can be

Attachmont 1  ;

to U-501879 Pago 3 of 7  !

fed to the station tnrough the lino from south l Bloomington or north Decatur (via Clinton Routo 54  ;

Substation) or both. The lino terminaten directly  ;

r (through a circuit owitcher) at the Emergency Recorvo Auxiliary Trannformer, which transforma the oloctrical f power to 4160-volt auxiliary power bun voltago. Tho 345-  !

kV offaito Power Syntom providen power to the station j through throo separato transminuion lines. Thoco linen ,

connect the station to tho Illinois Power Company grid at  !

the Drokaw, Rising, and Latham substations. All throo  !

lines terminato at the station switchyard ring bus which foods the Reservo Auxiliary Transformer (RAT), which in turn transforms the electrical power to tho 6900-volt and l 4160-volt auxiliary power bua voltago. Only one 138-kV  !

foodor and ono 345-kV foodor are required by the CPS t Technical Specifications. l The RAT has experienced no failuron sinco IP roccived ito  :

operatina licenso in September 1986. The only outage of l the off-sito power from the 345-kV uwitchyard occurred in  ;

lato 1900 due to a failuro of a 345-kV diaconnect nWitch, j This outage was of s1. ort duration (24 houro). [

In the unlikely event that the power courcos doacribed abovo become unavailable, there are two remaining }

operahlg dional generators on site. Diosol Generator 1A [

(DG1A) supplios power to Division I electrical equipment and DG1C supplios poWor to Division III olectrical +

equipment. Those operable diosci c') orator ut,ita aro

• capable of noquentially startine  ; supplying the power  !

requirements for cafo shutdowr .he plant, because of  ;

the divoralty of the power r os described above, the  !

increano in the allowablo ( -sorvice timo for DG1B is r justified. i I

With respect to the current statun of other ayatema at CPS important to safety, the following are currently out i of cervice, j EY.nica Statuo*/ comments j

-(1) Position indication The limit switch for  !

for Main Steamlino the position indication in  !

Isolation Valvo achedulod to bo repaired j 1821-F022D-(Post- during the next plant  ;

accident Monitoring shutdown.  !

Instrumentation) j (2) Drywoll atmosphere Parts to repair filter  !

particulato radio- paper drivo mechanism aro l activity monitoring expected to be rocoived on t system (Loak' September 6, 1991. Monitor Detection System) is expected to be restored shortly thereafter.

• As of September 6, 1991. [

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, _ _ _ _.____._.n_ . - _ __~ _ _. .__..____.___.________! _

T Attachmont 1 to U-601879 [

Page 4 of 7 Imminent restoration of the drywoll atmosphoro i particulato radioactivity monitor and the operability of l rodundant syntoms provido added anuurance that adoquato  !

safety will bo maintained during the timo parlod that the i roquanted waivor of complianco would be in offect.  ;

Regarding the nood for maintaining the picnt on-lino, CPS i la procontly generating approximately 30 porcent of the h total olectrical Ip customer load. It is octimated, however, that if CPS must nhut down, IP will continuo to I have c.doquato generating capacity.  ;

Mdit;10Bal Hitiaatina conditionn 1P contacted the National Weather Servico in Springfloid, I Illinois and hao evaluated the current and expected  :

weather conditions for the immediato service aroa, clear i weather with light and variable windo la forecast for the .

wookond. However, the forecast calls for a chango of

• scattered showers and thundorotorma Monday and Tuonday.

Tempqraturco for tho wookond are predicted to be moderato  ;

with higha in the mid-to-high eighties with lown in tho  ;

mid-cixtion. ,

Camnennatory Actionn }

The romaining operablo diocol generatoro aro ready to  !

perform their intended function in the unlikely ovant that they are nooded. In addition, no testing will bo  !

performod that might croato a transient to normal plant  ;

conditions during the extended timo interval. Also, no  !

nyatomo or equipment important to safoty which aro  !

associated with the redundant safety-related division  !

(Division I) will be removed from service for planned  ;

maintenanco or tonting during tho extended timo interval. l Further, both replacoment heat exchangora arc oncito and i IP is working on a continuous baolo to completo  ;

inctallation and rostoro DG1B to operablo utatuo.

I It should be noted that Action "b" of cps Technical  ;

Specification 2.8.1.1 alao requires that operability _of  ;

the remaining operablo diocol generatora be demonstrated ,

separately by performing surveillanco tests for starting i and loading thoso diocol generators if the diocol l generator which cauced entry into Action "b" becamo  !

f inoperable due to any cause other than proplanned proventivo maintenanco or testing. However, an discussed l previously, leakage through the heat exchangor tuben accociated with a particular dionol generator does not i rondor the diocol generator inoperable cinco the diesel  ;

can function with direct corvico water flow into the  !

l engincor water jacket. Entry into the Action statomont ,

! to replace the DG1D heat exchangers was dono on a  !

I voluntary bacia and is regarded as proplanned proventivo  !

l t

maintenance. Thorofore, no additional tonting (i.e.,

l

Attachment 1 to U-601879  !

Pago 5 of 7  !

L starting and loading) to verify operability of the r Division I and III diesel generators (DG1A and DG1C) was j required or performed. ,

Safety Significangp/ Basis f or_ No _ Slanificau.t._llManlil ,

CgnsideratioD j IP does not consider this request to be safety significant in view of the following  :,

1) With rocpoet to AC power, only the Division II DG is h currently inoperablo. As offsito power is available, sufficient redundancy existo (assuming no concurrent failuros) to provido omorgency power to ,

systems designed to mitigate the consequences of an i accident. [

2) Generally, operation under the provisions of an h Action Statomont is permittod for limited periods of  !

time. It is recognized that singlo-failuro critorin  !

may not bo not during such operation. IP believes that oporation with DGlu out of service for a period [

of tino longer than normally allowed but within the j noted limit constitutes no significant increano in  !

risk regarding the saf) opcration of the facility.

3) In addition, IP does not believe that the present  !

situation should require subjecting &ho plant to an l unnecessary shutdown. Although there is a cortain risk associated with tho increased allowed out-of- }

servico_timo, most challongos to plant systems occur 1 during startup and shutdown evolutions. Eliminating the risk associated with thoso events by proventing  ;

an unnecessary plant shutdown due to the current i action timo limit, is viewed to be a positivo i increase in plant safety.

4) With respect to executing a safe shutdown of the i plant if required, the plant design is such that  ;

safo shutdown to a cold condition can be achieved I with DG1B inoperable, particularly in view of the operability of all rodundant power sources and tho  :

operable status of systems important to safety. [

i According to 10CFR50.92, a proposed chango to the licenso (Tochnical Specifications) involves no significant L

hazards consideration if operation of tho facility in  :

L accordance with the proposed change would nots (1) involve a significant increase in the probability or i consequences of an accident previously evaluated, or_(2)  !

croato the possibility of a new or different kind of '

c accident from any accident previously evaluated, or (3) 7 involvo a significant reduction in a margin of safoty. >

This request is ovaluated against each of those critoria l below.- f 1

I

^

Attachment 1 to U-601879

. Page 6 of 7

1) As noted above, the proposed one-tino request would permit DG1D to be out of servico for a longer period of tino than normally allowed oy the Technical specifications. However, in view of the oporability of all other required on-sito sources and all required off-sito sourcos, Ip believes that the proposed request does not constituto a significant increase in risk with respect to the capability of safety systems to mitigato the consequences of an accident. Additionally, the proposed request would i permit a reasonable amount of timo to rostore the DG1B heat exchangers to a liko-now condition whilo avoiding an unnecessary plant shutdown and potential cha11ongos to safety systems. Thoroforo, the proposed request does not involvo a significant increase in the probability or consequences of any accident previously evaluated.

2) The propocod requent does not involv: any changes to the design or operation of the plant. Sinco no now failure modos aro introduced by the proposed request,fthe proposed request does not create the possibility of a now or difforont kind of accident '

from any accident previously evaluated.

3) Under the proposod request, the al. lowed out-of-service time for DGlB (although longer than normally allowed) would still be limited to a reasonable period of time. With DG1A and DGlc operable, the proposed chango does not involvo a significant reduction in the margin of safety normally onsured by the Technical Specifications with respect to the availability of omergency onsite Ac sourcoss Dased on the foregoing, IP has concluded that this request does not involvo a significant hazards consideration.

ggneludino Remarks It should be noted that the current MIC problem of DG1B l could be resolved through a number of options. As noted previously, the diosol generator is not rendered inoperable by the MIC condition since the DG could K perform its intended function with flow directly from the service water' system into the jacket water system. One possible (but unrealistic) option would be to simply continuo operation with the heat exchangers "as-is."

Another option would bo to plug the leaking tubes in lieu of 'oplacing_them. Neither of those options, however, would be offective in mitigating the MIC condition or proventing a potential near-term future nood to again address degradation of the DGlB heat exchanger tubos duo to MIC.

Attachmont I t to U-601879

'- Pago 7 of 7 I The third option in to replaco the heat oxchangers. Thio  ;

will rostore the heat oxchangers to a liko-new condition an IP roaddronnou its long-term solution to the MIC t problem. IP fools that thin in the appropriato courso of action. The proposed request would support comploto l replacuent of lath heat exchangora (for the 12-cy11nder l nnd 16-cylindor enginos), thus precluding the  !

possibility, in the near term, of having to again romovo the DG from servico in order to perform additional l ropaira duo to MIC.  ;

Plant and grid conditions are auch that now la an appropriate tino to request a waivor of compliance in ,

ordor to implomont a thorough (short-term) fix to the MIC [

problem for DG1D.

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