ML20128Q004

New England Coalition on Nuclear Pollution Comment in Opposition to Proposed Finding of NSHC

ML20128Q004
Person / Time
Site:	Vermont Yankee
Issue date:	02/22/1993
From:	Curran D HARMON, CURRAN, SPIELBERG & EISENBERG, LLP., NEW ENGLAND COALITION ON NUCLEAR POLLUTION
To:
Shared Package
ML20128P995	List: ML20128P990 ML20128P998 ML20128Q004 ML20128Q010
References
FRN-58FR5427 58FR5427, NUDOCS 9302260079
Download: ML20128Q004 (15)

Text

. . .- -

. .r 3 i .h~

I l

[; UNITED STATES.OP ANERICA m

BEFORE'TNE NUCLEAR REGULATORY COMMISSION l

~

)

In the Matter of )

)

Vermont Yankee Nuclear )

L Power Corporation ) Docket No. bO-271-OLA-i )

(Vermont Yankee Nuclear )

Power Station) )

)

N124 ENGIAND COALITION ON NUCIRAR POLLUf10F.'S i'

COMMEriTS IN OPPOSITION TO PROPOSED FINDING OF NO SIGNIFICANT. HAZARDS CONSIDERATION lutL2dyction  :

On January 21, 1993, the Nuclear Regulatory Commission

("NRCr or " Commission") issued public notice of an operating li-conse amendment request by the Vermont Yankee Nucicar Power Cor-poration (" Vermont Yankee") , which would permit Vermont Yankee to perform extensiNa maintenance on the Vermont Yankee Nuclear Power Station's ("VYNPS's") "B" diesel generator for fourteen days dur-ing the current operating cycle, while the reactor is operating

?

. at powar.1 58 Fed. Reg 5,435. The NRC proposes to make a determination of no significant hazards consideration regarding 8

the proposed license amendment.

The New England Coalition on Nuclear Pollution ("NECNP") op-poses the proposed finding of no significant hazards considera-tion. NECNP's Opposition is supported by the affidavit of Robert D. Pollard, a nuclear safety engineer. Attachment 1. As dis-1 1 NECNP has requested a hearing on the proposed license amend-ment. New England Coalition's Request for Hearing on Proposed Operating License Amendment (February 22, 1993).

.9302260079 930223

-PDR -PR 1 MISC 58FR5427 PDR

a t, T

~

..3-

' cussed belov e the intentional disabling of:one~of Vermont Yankee

. Nuclear Power Station's . ("VYNPS's") two diesel (generators would violate General Design-Criterion ("GDC") 17_ , the NRC'sLfundamen-tal requirement that onsite_ electric power supplies must "have sufficient-independence, redundancy,_and testability.tolperform .

their safety functions assuming a r. ingle failure," 10 C.F.R. Part 50, Appendix A, GDC 17. In addition,_the proposed amendment violates the technical specifications for VYNPS, which contain no provision for deliberate removal of the diesel generators from service during power operation. On its face, ty, 2-2 the intentional-disabling of an essential safety system, in  ;

violation.of the NRC's General Design Criteria, NRC regu3etory guidance, and VYNPS technical specifications, raises significant hazards considerations. Accordingly, pursuant to Section i

189a ( 2) ( A) of the Atomic L orgy Act, 42 U.S.C. .$ 2239(a)(2)(A),

the NRC must provide a hearing on the proposed license amendnent b_elog it can be issued.

1. STATEMENT OF FACTS VYNPS has two standby diesel generators which constitate the onsite electrical power supply for the plant's structures',-.sys-tems, and components important to safety. GDC 17 requireb that each of the diesel generators must be safety grade and_ designed.

~

to " provide sufficient capacity and capability"'to maintain plant safety during-design: basis-accidents assuming ailoss of offsite' power.

" Pursuant to GDC-17 and the' plant's Limiting Conditions for Operation ("LCO's") , VYNPS cannot be operated at power unless- l l

L.  ;

I

. ._ .. -_ - . _,. . m. . .

I e

• A

-'3 -'

7 d

both'diese1Lgeneratorstaro7 functional'. As~provided-by Technical?

~

-~

4 Specification'("TS"_)'3.10.A,1, ,

. 4 .

BothLemergency_ diesel generators shall be operable 4and capablo of_ starting and reacningLrated-voltage:and fre-quency in not more--than 13 seconds.

A' limited exception to this requirementiin'provided infTS 3.5.H.1:

o-During any period when one of the; standby diesel gener-

. ators is inoperable, continued. reactor. operation is' 4 permissible only during the' succeeding lseven days,- pro-vided that all of the Low Pressure Core Cooling and Containment Cooling Subsystems connecting to_the. ,

operable diesel generatorfshall beJoperable. -

d However, TS 3.5.H.1 also. states-that "If this requirement cannot. l be met, an orderly shutdown shall be initiated arv$ the reactnt' shall be in the cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />."  :

On three previous occasions, Vermont Yankee' has invoked;TS_ .

,e 3.5.H.1 for the purpose of repairina diesel generators at. power.--

In_1990, the NRC granted Vernont ~Yanken perrsission : to inten- f tionally disable and overhaul one of its diese'_1 generators whilo-operating at power, on the ground that a-local hydroelectric ~sta-tion was available to.provido backup power.2 See Memorandum from-Thomas E. Murley, Office of Nuclear Reactor Regulation, toLThomasj T. Martin, Regional Administrator, Region I (May 18, 1990) and enclosures,_ Attachment 2.

p __

2 As discussed below, tha practice-of intentionally disabl'ing dieselLgenerators while at power in order to make rcutine '

o repairs is not rermitted by either GDC 17 or the - technical:

specifications for VYNF3. Thus,.NECNP believes that the URE erred when it granted permission for tho'1990 repairs.

R c.

w - .-

F _ y -,

Last year; on two ceparate occasions a month apart,:Vermonts Yankee declared its "A"-diesel generator inoperable after "ab-normalities were encountered with=the jacket' cooling system."

Letter-from Warren P. Murphy, Vermont Yankee, to UnitedLStates Nuclear Regulatory Commission re: Proposed Change-_No. 166, One-~ .

Time Extended Emergency Diesel Generator (EDG) LCO Period to Sup-port Maintenance Activities.at 2'(December 15, 1992) (hereinafter.

" Murphy Letter"), Attachment 3. On May 28, 1992, and again.'on:

June 23, 1992, Vermont Yankee began dieral generator repairs while the reactor was at power, as permitted by TS 3.5.H.llfor

" inoperable" diesel generators. When Vermont Yankee fobnd'that these repairs could not be. completed within 7 days,.as required by TS 3.5.H.1, it applied for and received temporary' waivers ,

which allowed a one-day extension for the repairu begun in May, and a two-day extension.for the repairs begun in June. Eggt BVY'92-068., Letter from Warren P. Murphy, Vermont Yankee, to United States Nuclear Regulatory Commission (June 3, 1992); BVY 92-074, Letter from Warren P. Murphy, Vermont Yankee, to United Stater l

- Nuclear Regulatory Commission (June 29, 1992), Attachments 4 and

- 5, respectively. ,

According to Vermont Yankee, surveillance of the "B" diesel generator "has not revealed-any indication" of the problems which ,

rendered "A" diesel generator inoperable. Murphy Letter at 2.

Nevertheless, Vermont Yankee deemed-it "pruie '," to make-the same- -

repairs to the "B" diesel generator that it had made to--the="A" diesel' generator "at the earliest:oppartunity." Id. Rather than; I-

)

e r ,,ve .c - - y = sr =

f L "

i. .

L waiting until the next refueling outage or scheduling an outage i

to make the repairs, Vermont Yankee submitted a' letter to NRC re-questing a change to TS 3.5.H.1 which would allow a "one-timeLex - ,

tension" from the LCO of 7 days to-14 days in which to-make those- '

repairs, as well as to conduct the routine 18-month overhaul of' the diesel generator. Murphy Letter, Attachment 3. On January 21, 1993, the NRC published a Federal Register notice of the. pro--

posed license amendment, along with a proposed finding that no F

pri.or hearing on the amendment is required because it poses no -

significant htcards consideration.

II. THE PROPOSED LICENSE AMENDMENT POSES SIGNIFICANT HAZARDS CONSIDERATIONS.

A. Statutory and Regulatory Framework Pursuant to Section 189a(2) (A) of the Atomic Energy Act and 10 C.F.R. 50.92(c), the NRC uay not issue an operating license amendment before granting a public hearing unless it determines' }

that the proposed amendment poses "no significant hazards consid-eration," i.e., that the amendment would not: -,

(1) Involve a significant increase in the probability or consequences of an accident previously evaluatsd; (2) Create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) Involv.a a significant reduction in the margin of-safety.

In passing the enabling legislation for thic regulatory provi-sion, Congress recognized that issuing the order in advance of a hearing 1would as a J practical matter, foreclose the public's right to have

-its views considered. In addition, the licensing board would often be unable to order any substantial relief as a result of an after-the-fact hearing.

n i

1

~ - - . . - -

s. 6 ..

Conf. Rep. No.97-884)-_97th'Cong.,--2d_Sess., at 37-38 (1982).

--Thus,, the: conferees noted their intent that-

-in determining (whetheria proposed license-amendment in-volves no-cignificant hazards 1 consideration,_the Com-mission should.be-especially sensitiveLto the issues = .

posed by license amendments that have irreversible con-sequences (such as those permitting anJincrease in.the

-amount-of effluents or radiation emitted-from a facil-

• ity pr allowina a facility te_ operate forfa ceriod of

- time withqpt full safety protqctiqng. )

Id. (emphasis added)

In response to Congress' expression of concern, the.Commis- ,

sion "made clear" in the preamble to S 50.92 that an amendment which allows a plant to operate at full power _during which one or_more safetyfsystems'are_not operable would be-treated in the same way as other ex-amples considered.likely to involve a significant hazards consideration.

'FinaljProcedures and' Standards on No Significant Hazards Consid-erations, 51 Fed. Reg. 7,744, 7,750,_ Col. 3 (March 6,-1986).- In addition, the Commission " charge [d] the NRC staff to assure that doubtful or borderline cases are not found to involvo no sig -

nificant' hazards consideration." 51 Fed. Reg.'at-7,753, Cols. 2-3.

B. The Proposed License Amendment Raises Significant Hazards Considerationr.

The circumstances of this case, involving the disabling of a mejor safety component in violation of NRC Genaral Design Criteria and VYNPS technical specifications, raise'signifjoant hazards considerations in-the starkest terms. Even were'these violations:nore " doubtful or borderline" (51 Fed. Reg. atJ7,753, cols, . ; 2-3 ] , the serious safety questions' raised _by the proposed 4

9Y g y -

g -

y e

amendment would dictate against'the issuance of.a no'significant i

hazards consideration finding, and require the granting of a prior hearing on Vermont Yankee's proposed license amendment.

1. The Proposed Amendment Involves the Intantional Disabling of' A Safety System, In Violation of GDC 17.

Under the Commission's standards for finding no significant hazards considerations, p_eg 51 Fed.-Reg. at 7,750, Col. 3, there can be no question that the proposed amendment raises "sig-nificant hazards" considerations, because it would allow the VYNPS to operate "at full power during which one or-more safety systems (i.e., the "B" diesel generator) are not operable," in direct violation of GDC 17. Tha importance of compliance with GDC 17'cannot be gainsaid.- GDC 17 is one of the NRC's " minimum requirements" that establishes the " principal-design criteria" for " structures, systems, and. components that provide reasonable assurance that the facility can be operated without-undue risk to the health and safety of the public." Introduction to 10 C.F.R. Part 50, Appendix A. In evaluating the sufficiency of the onsite power supply to power safety systems, GDC 17 assumes that offsite power systens are un;vailable, and requires the provision of onsite power supplies "with sufficient independence, redundancy, and testability to perform their safety functions assuming-a singlc failure." Thus, in evaluating whether Vermont Yankee's' dieael generators comply with GDC 17, it must be assumed that1(a) no offsite power is available and (b) one of the two diesel gon-erators has failed. If the remaining diesel generator were in-

l l

s . 8 --  !

tentionally-disabled, as proposed in Vermont-Yankee's-license amendment application, VYNPS would have no protection against a-  ;

single failure of a diesel generator, in direct violation of GDC H

'17.

Moreover, it is clear that such a violation'of GDC 17 could increase accident risk at VYNPS in all three of the aspects by which NRC judges "significant hazards" under 10 C.F.R. S

50. 92 (c) (1)-(3) . With respect to the first criterion, the inten-tional disabling of the "B" diesel generator would significantly-compound the " probability or consequences ~d associated with a ,

"previously evaluated" accident --

i.e., the unavailability of one of the diesel generato:.s during a loss of offsite power, as contemplated by GDC 17. If the "B" diesel generatorfis inten-tionally disabled and the "A" diesel generator must be assumed to:

l be disabled as required by GDC 17, this would leave VYNPS-without

[

.gny source of onsite power. Under such circumstances, a design j basis accident would be transformed to a beyond design basis ac-cidenc, with-the potential for meltdown and catastrophic con-i sequences. Thus, the proposed amendment raises significant hazards considerations under the second criterion of $ 50.92(c).

Finally, the significantly increased probability and consequences of a serious accident would obviously involve a "significant reduction in the margin of safety" at the plant, thus establish-ing a significant hazard under S 50.92(c) (3) .

l l

i ,.

t

l

2. The Intentional Disa511ng_of a Diesel Generator for Repairs at Power Violates Vermont Yankee's i Technical Specifications and NRC Regulatory Guid-ance.

Vermont Yankee's operating license amendment application is- ,

based on the assumption that it is already entitled,_through its technical specifications, to disable and repair the "B" diesel generator at power, and that all it requires is an extension of the seven-day period for repairo allowed by TS 3.5.H.1.. Rag Mur-phy letter at 1. However, Vermont Yankee's position is based on an incorrect interpretation of VYNPS's technical specifications.

In fact, the intentional disabling of a diesel generator for repairs that could otherwise be postponed until a' planned outage violates the VYNPS technical specifications.

Pursuant to GDC 17, the principal VYNPS technical specifi-cation governing standby diesel generators, TS'3.10.A.1, requires that both diesel generators must be " operable and capable of reaching rated voltage and frequency in not more than 13 sec-onds." TS 3.5.H.1, upon which Vermont Yankee relies,-creates a limited exception to this rule, providing that "During'eny period when one of the standby diesel generators is inoperable, con-tinued reactor operation is permissible only during the_ succeed-ing seven days . . .

Vermont Yankee apparently interprets the term " inoperable",

as used in TS 3.5.H.1, to include thc intentional disabling of' the diesel generators for routine or non-urgent' repairs. Th".

as read by Vermont Yankee, TS 3.5.H.1 permits it to intentionally disable one of its diesel generators for repairs at any time, as-

s a , . .

long as_the. duration of the repairs does-not-exceed 7 days'.- How-

.ever, such a-broad = interpretation of the exception in TS'3.5.H.1' vould swallow the general rule established by GDC 17'and TS 3.10.A.1, that VYNPS cannot operate unless both diesel 1 generators; are operable and available. In effeut, under Vermont' Yankee's1 interpretation of the technical specifications, a diesel genera-tor could be disabled for repairs every two weeks, as long as the repairs could be finished in seven days.

Vermont Yankee's interpretation of its technical specifica -

tions is also inconsistent with the guidance set forth in Reg.

Guide 1.93, which contemplates at power repairs only ac Jr the risks of shuttina down the reactor have beerthalanced aaainst- the-risks of continuina to operat9 with only one diesel aenerator:-

Under certain conditicns, it may be safer to continue operation at full or reduced power for a limited time than to effect an imnediate shutdown on the loss of-some of the required electric power sources. Such de-cisions should be based on an evaluation that. balances the risks associated with immediate shutdown-against i those associated with continued operation. If, on balance, immediate shutdown is the safer course, the unit should be brought promptly to an orderly shutdown, and to a cold.shutdrwn as soon as possible.- For exam---

ple, the risks associated withuan immediate shutdownLon the loss of onsice a.c. power supply during +.' period of light system load would tend to be less than those-dur-ing a peak load period because the stability of the offsite power system would be relatively higher.- If, on balance, centinued. power operation _is tho' safer course, the period-of continued operation should be used to restore the lost-source ~and to' prepare-for an-orderly shutdown, provided, of course, that-these ac-tivities do not risk further degradation of the elec--

tric power-system or in any way jeopardize plant.

safety.

Reg. Guide 1.93 at 1. Under this standard, the only acceptable justification for repairing the diesel generators-at power would

. , ~.. ,_ - - .- - .. . ..

c ' .: .,

be a' showing _that it is safer to do that than to shut-the-planti down'-- an crgument~that could be made only_if the-diesel; genera -

tor was unable to function, or so-unreliable as-to be effectively-inoperable. Those c'rcumstances i do not exist.here, where the "B"-

diesel generator is functional, and Vermont Yankee seeks permis-sion simply to make non-urgent repairs and to conduct routine maintenance'.- Thus, under the guidance of Reg. Guide 1.93, the VYHPS technical specifice.tions cannot be read to permit the in-' .

tentional disabling of the diesel generators.in order-to-perform -

routine repairs.

Because Vermont Yankee's proposal to intentionally disable the "B" diesel generator during power' operation constitutes a ,

departure from its technical specifications governing important safety functions, it necessarily raises "significant-hazards-con- ,

siderations." In fact, while the NRC staff concluded ~(erroneous-ly, NECNP submits) ttat Vermont Yankee's 1990 bid to overhaul its ,

diesel generator during power operation was sal.ctioned by its technical specifications, the staff noted its concern that "this maintenance practice poses a noteworthy-risk " Memorandum from-J. Johnson, Chief, Reactor Projects Branch No. 3,' Region I, to R._- -

Wessman, Directorate I-3, NRR (April 6,.1990), Enclosure to At-tachment 2.

1 D

,-r ,

-w-'r

s

3. The Existence of the Vernon Tie-Line would Hot Compensate for the Disaoled Diesel Generator Under GDC 17.

Vermont Yankee attempts to satisfy the no significant hazarris Otandard by arguing that there will be no significant change in the types of potential acc! dents at VYNPS or decrease in the margin of safety of the plant, "because of the availability of other plant electri:al systems, including the Vernon tic line" from a local hydropower station., Murphy letter at 5. However, this argument ignores GDC 17, which provides quite clearly that offsite power sources, such as the Vernon tie line, cannot be used as substitutes for onsite power sources in order to satisfy the requirements for backup power supply.

Moreover, even if GDC 17 could be ignored, and the Vernon tie line could be credited as a backup electricity supply, far too many questiors exist about the capacity and reliability of the Vernon tie line as a source of backup powar to safety sys-tems. For instance, as Vermont Yankee has conceded, it is im-post.ible to test the Vernon tie-line under a full station black-out load. BVY 92-94, Letter from Leonard A. Tremblay, Jr., Vor-l mont Yankee, to United States Nuclear Regulatory Commission, re:-

l 10CFR30.63 Station Blackout (SBO) - Response to NRC Request for l

Additional Information, Attachment to BVY 92-94 at 3 (July 31, 1992), Attachment 6. Moreover, Vermont Yankee admits that "[dlue to the vintage of the hydro station generators' voltage i:

l regulators," it is unaole to " analytically predict" what the voltage levels wi)1 be upon application of the largest load to the 4160-volt emergency bus. Id. at 3. Ir. stead, Vermont Yankee

, - 13'-

4 ,

rellas on the_ engineering judgment'of hydro operators"and dis-patchers'from outside Vermont Yankee, who are'not~ licensed;byLNRC and who have no responsibility-for.the safety of VYNPS. 'In_ sum, Vermont Yankee han neither empirical evidence nor analytical results to demonstrate that the Vernon tie line has " sufficient capacity and capability" to meet the requirement 3 of GDC 17. Ac-cordingly, the existence of the Vernon tie-line provider ru) basis for a no significant ha'ards a finding in this case.

CONCLUSION Vermont Yankee has failed to demonstrato that the proposed _ i license amendment involves no significant hazards considerations; in-fact, on its face, it would significantly increase the risk to public health and safety posed by operation of the VYNPS. Accor-dingly, the NRC should reverse its proposed finding of no sig-nificant hazardu considerations, and order a prior hearing'on the proposed licansc. amendment.

Respectfully submitted, f ane curran . . -

HARMOhi, ' CURRAli, GALLAGHER &

SPIELBERG 2001;"S" Street-N.W.

Washington,'3.C. 20009' -

'202) 328-3500 Counsel to NECNP Fehraary 22, 1993 O

d I

O

hl 1 UNITED STATES OF AMERICA. Attachment 1 BEFORE THE NUCLEAR REGULATORY COMMISSION

)

In the Matter of. )

)

Vermont Yankee Nuclear )

Power Corporation ) Docket No. 50-271-OLA

)

(Vermont Yankee Nuclear )

Power Station) ) ,

)

AFFIDAVIT OF ROBERT D. POLIARD I, Robert D. Pollard, do make oath and say:

1) My name is Robert D. Pollard. Since February 1976, I have been employed as a nuclear safety engineer by the Union of Concerned Scientists. My business address is 1616 P Street, N.W., Washington, D.C. 20036. Previously, I was employed by the United States Nuclear Regulatory Commission as a Licensing Pro-ject Manager for commercial nuclear power plants.

2) In May 1959, I enlisted in the United States Navy and was selected to serve as an electronics technician in the nuclear power program. After completing the required training, I became an instructor responsible for teaching naval personnel both the theoretical and practical aspects of operation, maintenance and repair for nuclear propulsion plants. From February 1964 to' April 1965, I served as the senior reactor operator, supervising the reactor control division aboard the U.S.S. Sargo, a nuclear-powered submarine. In May 1965, I was honorably discharged from the U.S. Navy and attended Syracuse University, where I received the degree of Bachelor of Science magna gym laude in electrical engineering in June 1969.

3) In July 1969, I was nired by the United States Atomic Energy Commission (AEC) and continued as a technical expert with t.a AEC and its successor, the United States Nuclear Regulatory-Commission (NRC) until February 1976. After joining.the AEC, I completed a year of graduate studies in advanced electrical and nuclear engineering at the Graduate-School of the University of New Mexico in Albuquerque. I subsequently advanced'to the posi-tions of Reactor Engineer (Instrumentation) and Project Manager with AEC/NRC. As a Reactor Engineer, I was primarily responsible for performing detailed technical reviews analyzing and evaluat-ing the adequacy of the design reactor protection systens, con-trol systems and emergency electrical power systems in propos9d nuclear facilities. In September 1974, I was promoted to tlg nosition of Project Manager and became responsible for safety reviews of applications for licenses to construct and cperate several commercial power plants.

l t

1

4) In the course of my six and a half years with the AEC and NRC, I performed technical reviews, analyses and evaluations of designs of systems and components necessary for safe operation of reactor facilities under normal,-abnormal and emergency condi-tions for the purpose of determining-whether such systems com--

plied with NRC rdles and provided an acceptable _ level of safety for the public.

5) For the past fifteen years, I, along with other members of the Union of Concerned Scientists' professional staff, have conducted numerous studies pertaining to the safety and reliability of nuclear power plants, both on a generic and plant-specific basis, fI have provided technical analysis for UCS's participation in rulemaking proceedings before the Nuclear Rcgulatory Commission and for UCS's litigation against the NRC for failure to fulfill its responsibilities under the' Atomic En-ergy Act. I testified before the President's Commission on the i Accident at Three Mile Island which investigated that 1979 acci-

• dent. I participated as an expert witness in the NRC's ad--

judicatory proceeding on matters pertaining to reactor safety be-fore numerous committees of the United States Congress and vari- ,

ous other state and local legislative and administrative bodies.

Thus, my 23 years of professional experience on the technica.1 staffs of the AEC, NRC, and UCS have given me first-hand knowl-edge of NRC regulations and how they are developed, administered, I and interpreted.

l

6) I have reviewed all of the documents referenced in New England Coalition on Nuclear Pollution's Comments in Opposition to Proposed Finding of No Significant Hazards Consideration (Feb-ruary 22, 1993). I am also familiar with NRC regulations and regulatory guidance governing the design and operability of diesel generators.

7) The factual statements made in the attached New England Coalition on Nuclear Pollution's Comments in Opposition to Pro-posed Finding of No Significant Hazards Consideration are true and correct to the best of my knowledge and belief.

Robert D. Pollard Subscribed and sworn to before me this __ day of February, 1993.

Notary Public My Commission expires .

4

- a --.

pt_ sty

%. UNITED STATES

% *p

- NUCLE AR AEGULATORY COMMISSION Attachment 2 EVAlest4010Ny C 20615 *

- t e

ts,b'+A.....-

K [e l my s i neo s T

MEMORANDUM FOR: Thomas T. Martin Regional Administrator, Region 1. >

FROM: Thonas E. Murley, Director Office of Nuclear Reactor Regulation .

SUBJECT:

USING THE OUTAGE TIME ALLOWED BY THE LIMITING CONDITION-FOR OPERATION FOR OVERHAULING AN EMERGENCY O!ESEL GENERATOR WITH THE PLANT OPERAT1HG AT. FULL POWER 1 share the concern you expressed in your May 2,1990 note (enclosure) to me regarding intentional entry.into an LCO (limiting condition for operation)-

action statement in Mode 1 to overhaul a diesel generator.- This concern relates to the broader issue of routine entry into LCOs tu perform maintenance, which appears to be a comon practice among licensees. preventive In the.

case of Yermont Yankee, certain design features and lice".see comitments led the staff to conclude that an acceptable level of safety would be maintained.

while the licensee was overhauling the diesel generator at power. The Question '

is whether design to doittheis acceptable same. Thefor licensees whose plants'have a less forgiving .

staff does not want to discourage licensees from doing preventive maintenance at power, because of the potential for achieving better reliability; but it should be done in a manner that decreases overall plant risk.

The NRR staff is coasidering the issue of routine entry into LCO action statements for performing preventive maintenance. Diesel generator overhaul will, of course, be addressed.

In the interim, it may be appropriate for the regions to identify licensees that routinely overhaul diesel generators in Mode 1 and determine if they have evaluated the adequacy of the technical bases for doing so. Licensees that de this should adhere to the following conservative principles: '

(1) The practice should represent a net safety benefit and be warranted by operational necessity, not just by convenience.

(2) The practice should not be abused by repeated entry into and exit from the LCO.

(3) The removal from service of safety systems and important non-safety.

equipment should be minimized during the overhaul, including offsite power sources.

(a) Any component testing or maintenance that' increases the likelihood of a plant transient should be avoided; plant operation should be' stable during the overhaul.- (This could include consideration of degraded or out-of-service balance of plant equipment.) /

40W~p

MAY; 18 1000L

.:2 - -

-Tt.tre rey te ether steps Le) cec these thetilicensees can'take to minipiireithe:

rit t associette with_ rta.uir9-a diestl generator- f rer service for ar extendet- i period of tire.

hRR generally accepts the' practice of licensees perforring preventive s.ainte.

nance at power, and this includes diesel generator overhauls, but.only e.f ter careful planning and if the safety benefit is clear.

Original signed by,-

• Thocas1. Wrley Thorr.as E. Murley, Director Of fice of Nuclear Practer Regulation

Enclosure:

As stated-cc: 5. C. Ebneter. Ril A. E. Lasis. R111 R. C. Martin, Rly

'J. E. Martin. RV 0157F I EUT I0t. :

C'!c h/i LCC/ R/F Central Files T emu' ley .CEPessi CHBerlinger -

FJMiraglia JACalvo D;Fischer WTRussell RMLobel JuRoe DM rutchfield SAVarga -JERichardson JH5niezek FPGillespie - 0TSB Members E!.3ritnes GMetolahan '

JGPartlow ACThadani >

000Urthi FLAME: MEMC MARTilt l'URLEY LCBEL ~

• (See previous' concurrence) -

. . deJY

• 0TSE:LCEA:HER *C:0TSB:00EA:hRR

• Tech. Editor L

RMLebel* JAtalvo* , -

-0:

Cf g }/ j ALT:hRR WTRussell -

05/14/90 _05/14/90 -05/15/90 CE//j90, -

5/g/90 g.

5l,..".

' CC i t.F i f,. -s FJf tir 11Murley C5/j / 0 05/ /90 '-

4 is s - - - .- , . - .

fnClos'Ure

~

/  % . . - UNITED STATES -

l= , a- - NUCLEAR REGULATORY COMMISSION

{ - nasastaeotoar, o, c.nosos .

3*****,f.

May 2,11990-

=

+

NOTE FOR:' _-Tom Murley Frank Miraglia .

Bill Russell

SUBJECT:

VERM0hT YANKEE-Attached is_ correspondence I d_iscussed on May-1, 1990-regarding the i propriety-of Yermont Yankee's practice of using 7-day LCO to overhaul ,

diesel generators. Your staff gave me a_ supportable legal answer. Given YY's claim that others do the same, should NRC discourage this practice:as

.1 matter of policy in light of the DG's key role in accident mitigation? -

Tim

Enclosures:

1. Memo dtd 4/13/90 J. Johnson fm R..-Wessman

2. Memo dtd 4/6/90 R. Wessman ,.

fm F. Rose .

3. Memo'dtd 4/6/90 R. Wessman--

fm J. Johnson l -.

I

\-

er

~

.+, p w.

,9 s '. ; UNittosTATit ~

, y I7 NUCLEAR REGULATORY COMMIS$10N i

• ntoloN i i k ett aLLt%Datt poAD

. . . . . ',P Elk? 07 P A UL8t A, P(hW8 7LVANI A 1HC4

• y.DcfNC.21 (OR: APR 0$ W4 R. WessN.n, Dirwetcr, Project Directorate 1-3, NRR l N:

J. Jchnsco, PagionChief,.

I Paacter Projects Branch No. 3,

%*J* I C :

hM rc YAbyJ2 PLANS 70 O/DWut, AN D<DCDCf DIISEL CIhDATCR MctI A7 nJtL nn W p pese of this re-crard rt is to followp en our diseassion of of Vem30,1)90 Mwen W toplans nt Yanbe's regaest that NRR to cvutaul oneevaluate of the two thedappropriateness gererrters sttile the plant is cperatirq at fall pcwer.iesel The diesel renths, hat has si.nce stata:t that a 22-24 renth intamval isgererster a:=ep.2 dj er.el 1e. As cf April,1990 the cwthaul intarval for this renths if the cuezhaul is delayed to the text refuelirq cutage.9enera Altha.sh 73 3.5.M.1 allevs a 7 day IID for one diesel cast vt arvice ard this ti.no period is appsrantly sufficient 9enerator to cr= the cuartaul, ve q>estien s5 ether the re eval of such an plantrunt is at piece of safety-related eq.tip ent is prv$ent stwn the Ecuer.

severa*. util2 ties ard fcurd that this practica was not uniqae ardkhile ve t?at the h of their 75 do ret irdicate that this action is u a: cept 21e, we re ained concemed that this reinterance practice p:cas a rete-crthy risk.

in a ceniition du ' The diesel getwrator will prc6 ably not be sh:uld a Icss of off its p:: war cc:sAr.the overhaul to be gaicX1y tastored to service 1

i We this rtq>est ratter. that you review this issae for t generic HRR positlen en

A pcsiticn was taken b/ NRR in 1987 regantirq villful entryrtd.

.-dint vith into Stard.ed Technical Specification 3.0.3 for ene hour Ims ccccidartd appli p le ent cut-et-service, b.rt that pcsitten is not here. W scald apr eciata a prcrpt tw sme e toa_%

or thisitratter April 16,because 1990. Verrcot Yankee intertis to entar this 140 cr) se need to centact Ve:Tent IfYankee this practice is des ed unacceptable, ran69e ent prcrptly.

l Sincerely, 1N d

• Jch Chief Roactor Projects Branch 3 cci .

B. Bcrper NRR W. yare,,RI H. Elchettolz, SRI, Verrcnt Yankee W. Parclak J. Curr, R1 7

4 J. Wiggirs,, RI RI R. Callo, RI

/

R. Barkley, RI q_y4M. < gcyrY

,/' -

m l

e' .<ee, .'

4 V *

[

g.4 o

j UNITS 0 stats s NUCLE AR REGUL ATORY COMMISSION p natancto=,o c tessa

/ -

j g f thJ PIr0kACLH TOR: R. VessNn. ProjMt Ofrector =

ProjHt Dirttterat2 !.3 Division of Aeactor P.=ojMts I/II FROM:

raust Rosa Chief titetrical Systems Branch Divistun of $ysterts Technology StfBJEC7:

Yt3ONT YAHttt . PLANS TO OV[RHAUL AN (PIRGthCY DIE 5CL GEntRATOR WHILE A1 TVLL 90VER fn response to a morandum (undated, received 4/5/90 l from J. Johnson Reactor Projects Branch No. 3. Region I to A.1/essmn) . Director, t- Projec. Chief.

Of rectorate 13 hRR which requested HRR to raview Yarnont Yankte's (YY) plant.

to declare a seven day Lt0 to owerhaul an emergency diesel generator (EDG) while electrical LCO.

distribution system for its adequacy in the contest of t 0;r eealuation follows:

Our position on the subject eatter is based on the following inferration:

1.

Accord'og to yr's current Technical Specification (TS) 3.5.H.1. if one of the t=c COGS found to be inoperable, continued reactor operation is per.

citted LLC 0).

for seven days, i.e., seven days Liniting Conditions for Operation ,

2.

In addition to two onsite CD3s and four offsite power lines through tso startup transformers at YY, there is Vernon hydro station tie line-which is a dedicated lint (one nalf mile away) that can be connected cirectly to et%er of the emergency buses from the VY control room.

Thi, switchtrg operatton is covered by the current plant procedurts and operator training. This Itne has enough capacity to supply all the emera gency pcvar loads to safely shutdown the plant.

3. The hyc're station is energized continuous 1~. thereft 'e. there is no need to startup any equiteent; and it has encalient re114bt11ty demonstrated by having a history of only two unplanned outages (total of less than 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />) since 1965. . -

Contact:

P. Kang. $CL9/057 220812 -f

.. ~ 4

.(.,..b;,-g6fIIIY

, (o

, , , . .-/

1 m

~

i

2. Westran

+2 4

To ensure more reliability, YY has corritted to set up a preventive i raintenance program which includes inspection of the line regularly and testing the line everv other refueling by aligning it to one of the safety buses and supplying it with the needed power.

5.

Ve also agree with Y 's Lsurvey that this prettict fi.e.. overhauling or teeforming 16 ranth (DG surveillance during power operation) by declaring a seven day LC0 is not voique to YY. We find that such i

practice is necessary for those multi shit plants which are designed and operated with shared (DG configuratia 's -(e.g., Brunswick).

able [DG, this time period is apparently suffic: tat to perform At Brunswick for this case. the r3maining three available EDGs-would meet the

- single failure criterion for loss of offsite power safe shutdown but not for a C84 being eqbivalent to a standby EDG.The YY situation is exactly similar hhun the Therefore we see no signif fcant safety problem with YY's plans to overhaul an t00 curing a seven day LC0 while at full power.

7- ,-  :.1

, 3x s, . .,. A ' '"~ ?

faust Resa. Chief flectrical Systems Branch Ofvision of Systems Technology cci A. Th4Cani P. fairtile J. Xntght l c f.

6 4

e F

3

. . _ _ , _4._m _,. . . . m , ,_. ,- - - -. #. m ~ ,.. ,

m __ m.., .

.. _ , ___ m

• EIQ10NT YANKEE Attactacnt 3 ,,

N'UCLEAR POWER CORPORATION h

• #* M Fe.f r Rnad B'attlebofo. VT 0$301.r002 b.,f)

~

'NY vacitNmloot roce s .~ .,. .. m , ,,n ,

,. c ... .,..,,,..

_% 7'; . , :, . n ,

December 15, 1997.

BVY 92139 l

United States Nuclear Regulatory Commission 4 ATTN. Document Control Desk l Washington, DC 2055S I

References:

la) License No. DPR 28 (Docket No. 50 271).

(b) Letter, VYNPC to USN9C, BVY 92 060, dated -

June 3,1992 (c) Letter, USNRC to VYNPC, NVY 92 095, dated '

June 4,1992 (d) Letter, VYNPC to USNRC, BVY 92 074, dated June 29,1992 (e) Letter, USNRC to VYNPC, NVY 92127, dated July 1,1992

Subject:

Proposed Change No'.166, One Time Extended Emergwncy Diesel Generatur (EDG) LCO Period to Support Maintenance Activities Oear Sir:

Pursuant to Section 50.59 of the Commission's Rules and Regulations, Vermont-Yankee hereby proposes the following changes to Appenoix 'A of the Operating License [ Reference (a)].

P_Iggs,fgi_sflagf!

This request croposes to replace Page 94 of tne Verrnont Yankee Technical-Specifications with the attached revised Page 94 Section 3.5.H.1 on Page .94 presently stipulates a Limiting Condition for Operation of seven (7) days with~one' Emorgoney Dietal Generator out of service. This request proposes to change Section .

3.5.H.1 by allawing a one timo extension of the savon (7) day LCO to fourteen (14) days during the current operating cycle (Cycle 16) to permit extensive maintenance to -

be performed on the "B" EDG while_the reactor is at power.

S l n00 u!>

L 72P2M=M&gMg <

d -

mm.mmam p ga~ - e m w , n ,, maw.. w ,

.m-. ,g VCHMON T 1 ANKEc NUCL C AH POWCH COOfCR ATCH U i. Nuclear Regulatory Commission December 15,1992 Page 2 NRC approval of this proposed chango would allow cnritinued rn: tor operation for an additiona'seven days beyond the present seven day LCO parlod (14 days total) i for a one timo cylinder linor replacement and routine preventive maintenanco activities on the "B" EDG during the present power cycle ICyclo 16). The extension parlod will allow sufficient timo to perforrn the planned maintenance activity and to thoroughly test thn "B" EDG before returning it to servico.

63ason fpLQhance On May 28,1992, and again on June 23,1992, the "A" EDG was declared inoperablo. In each of those casos, during a routino monthly EDG surveillance, abnormalitios woro encountered with the jacket cooling system. Upon engine disassembly, cracks were discovered in two (2) cylinder liners. For each of these occurrences, Vermont Yankoo requested a tempomry waiver of compilance (References (b) and (d)) to extend the LCO porlod such thnt repairs and proper testing (

could be modo at power prior to tostoring the "A" EDG to service. Both of these requests were approved by NRC [ References (c) and (e)). In the second instance, the maintenanco performed included replacemont of all cylinder liners, on the " A" EDG, with now improved liners. Tb9 " A" EDG was returned to service within the extended LCO period and has since encountered no performanco problem related to the cylindet liner replacement.

Following each of these occurrences, Vermont Yankoo performed a detailed i Root Cause Analysis (RCA) to inventQate the cause of the specific failures. In addition, an EDG Task Force was assembled to review the overall EDG maintenance and surveillanco programs Scih of these efforts have been completed and a number of recommandations have been made to management. Vermont Yankee has already implemented sorne of 'he recommendallons and is in the process of implementing the remainder. One of the recommenostions was to replace cylinder liners on the "B" EDG coincident with the next scheduled overhaul.

Surveillance testing of the "O EDG has not revealed any indication of the cylindor linor problems that occurred on the " A" EDG. However, it is prudent to make the same improvements to the "B" EDG that have already been made to the "A" EDG at the earilest opportunity. As a result,Verrnont Yankee plans to perform replacement of all cylinder liners during the next scheduled 18 month overhaul of the "B" EDG, Dusing this malt tonance period, we also plan to replace the " inverted 'Y' housing" as a result of Vermont Yankee exporlonce with broken bolts on this componont in 1992 and a Fairbanks-Morse Service infortnation Letter (SIL). In addition, we will be perf orrning the proventative maintenance tasks normally associated with the scheduled 18 month overhaul of the "B" EDG.

w ,- , ,

s .

vCRMONT YANHECt NUCt.E AR POWER COHPORATON

. 'U.S. Nucloar Regulatory Commission Docomber 15,1992 Page 3 l

th18__f9Lghangg 1

Fourteen (14) days are required to complete the maintenance associated with ,

cylinder liner replacement, replacement of the "Invasted 'Y' housing" and perfortnence of the proventative maintenance tasks normally associated with the ocheduled 18 month overhaul of the "B" EDG. The scheduled 18 month overhaul, including post.

maintenance testing, typically requires most of the allowed 7 day EDG LCO period.

The cylinder linar replacement on the "A* EDG conducted in June, including the requ! red augmented testing, sequired moth than the allowed 7 day LCO. The augmented testing that is planned prior to declaring the "B" EDG operable includes:

operating the engino continuously for approximately twenty one (21) hours at loads varying from "no fond" to 100% load, allowing the EDO to cool down for a minimum of eight (8) hours, then performing an eight (8) hour operability run. The return of the "B" EDG to operable status would occur after successful completion of the first one (1) hour of the olght (8) hour operability run. This testing would be conducted with caroful monitoring of key diesel engine parameters to furthnr substantiate satisfactory operation.

In order to perform this extensive proventativa maintenance effort and the addllional task of replacing the cylinder liners, including special testing, additional amo is nooded beyond the existing seven (7) day LCO period provided in Technical Specifications. Therefore, Vermont Yankee is bequesting a one time extension of the present seven p) day LCO to fourloen (14) days to allow for implementation of these improvements during the current power cycle (Cycle 16),

i- Wo believe that approval of a soven day LCO extension will provide sufficient

( margin to repair and thoroughly test the EDG without compromising the continued cafn t

operation of the plant. As wo inoicated above, a significant portion of the additional l LCO time would be for "run in" of the new components and oporability testing. The l EDG would be available during this period, but not considered operable until teshg I has been satisfactorily completed.

l Upon NRC approval of-this proposed chango, Verrront Yankeo would then l- utilize the one time I,,CO extension for the express purpose of perfoiming the "B" EDG l maintenanco activity, doectlbed horoin, during Cycle 16 operation et powar. Vermont

! Yankoo is in the procots of preparing the neenssary procedures, schedules and procuring the parts and equipment necessary to ourform this malmenants activity, it is anticipated that we will be in a positnn to perform this activity sometima 'vithin the first four months of 1993.

, -- - - e

VcRMONT YANKE.E NUCLE AR POWEH CORPORATON

t 1 Wu Hegulatory Commission 4

n;,m ui15,1992 iG94 As required by Technical Specifications, the alternate EDG will be tested and

.. .if the Low Prossure Core Cooling and Containment Cooling Subsystems connected to the operable EDG will ba verlfled operable prior to deching the "B" EDG' Inoperable and entering the LCO period.

In addition, Vermont Yankee procedures require the Stallo* Manager of the Vernon Hydro St3 tion to be contacted to snsure that continued avalidility of power-is expected on the d9dicated tie line to Vermont Yaiskva prior to and for thw duration of the LCO period.

A thorough review of ali other planned survolllance activitlos will be performed prior to e'itering the LCO period and only those determined to be of Ivw risk to equipment or system availability will be allowed.

Safety Consideratiojig in order to provide added assurance that the " A" EDG will perform its function if required, the " A" EDG will be tested for operability prior to entering into the "B" EDG LCO period. The Technical Specifications also require that durli,g the LCO period, all terrainin0 Low Pressure Core Cooling and Containment Cooling Systems connected to the operable EDG remain operable. Vermont Yankee has developed a detailed LCO mainter:ance plan for EDO LCO maintenance. This plan has been successfully used during prior EDG LCO maintenance and will be invoked for this ovclution as well, in addition, the Vernon Hydro Stat:on dedicated tie-line, which historically has demonstrated a very high reliability, is required by Vermont Yankee.

plocoduro to be available to supply power to Emergency Bus 3 during the "B" EDG LCO Atiy previously analyzed event postulated during the seven day extunsion period can be mitigated by the other ava'.lable systems. The proposed LCO extension has  :

no significant impact on the consequences of any previously analyzed event.

Tho proposed extensior would allow the "B" EDG to remain inoperable for an additional seven days beyond the procent savun day LCO allowed by Technical Specifications. The unavailabiisty of one EDG is not a past of the initiation of any of the analyzed accidents. Therefero, the proposed change does not increase the probability of an accident previously evaluated.

This proposed change has been reviewed by the Vermont Yankee Plant Operations Roview Committee and the Vermont Yankee Neclear Safety Audit and Review Committee.

^

, 4 4

VEHMONT YANKEE NUCLc AR POWER CORPORATK)N

- 'U..S Nuclear Regulatory Comraission December 15,1992 Pago5 Stanificant Hagords Consideratism The standards used to arrive at a determination that a request for amendment involvos no significant hazards consideration are included in the Commission's Regulations,10CFR50.92, which state that operation of the f acility in accordance with the proposed amendment would not: 1) Involve a significant increase in the probability or consequences of an accident previcusly ovaluated, 2) create the -

possibility of a new or different kind of accident from eny accident previously -

evaluated, or 0) involve a signllicant twduction in a margin of safety.

The discussion below addresses the prop > sed change with respect to these threo critoria and demonstratos that the proposed amendment involves no significant hazards consideration:

1. Doos the change involve a significant increase in the probability. or consequences of an accident previously evaluated?

The proposed chango would not involve a signMicant increase in the probability or consequences of an accident previously evaluated. As discussed above, a coven day extension to an afrondy existing seven day LCO period would involve no significant increase in the probability of occurrence or consequences of a design basis accident during the extension period.

2. Does the change creats the possibility of a new or different kind of accident from any accident previously evaluated?

The proposed change would not create the possibliity of a new or diffeient kind of accident from those previously evaluated. The proposed changs would have no impact on the possibility of a new or different initiating evant. The proposed chang 3 requests a one time extension of 7 days beyond the already authorized 7 day "B" EDG LCO Any previously analyzod everet postulated duririg the sovan day extension period can be mlisgated by the other available systems.

3. Does the change involve a significant reduction in a margin of safety?

The propuod change would not involve a significant reduct:en in the margin of safety. As discussed above, approval of tl'is request involves an insignificant reduction In the margin of safety because of the availability of other plant electrical systems, including the Vorror tie line, and the short duration of the extorision period.

i VERMON r TANKEC NUCL.C AR POWER CORPORAflON i o, .

U.S. Nucioar Regulatory Commission December 15,1992 Page 6 .

1 i

Based upon the above, Vermont Yankee concluctss that the propsed change l does not constituto a significant hazards consideration as defined in 100FR50.92(c).

SchedubLof Chance i This proposed change will be incorporated into the Verinont Yankee Technical Speellications ss soon as practicable following receipt of your approval.

Vermont Yankee plans to utilize the one time extended LCO provision for the .

"B" EDG during the current power cycle (Cycle 16).

Vermont Yankee w.:1 keep the NRC Senior Resident inspector informed of our progress in preparing for this maintenance activity and will notify the NRC Senior Resident inspector in advance of emering this extended maintenance LCO.

We view the proposed activity as a positive contributor toward our inutual goal of mairttaining a high degree of plant safety through improved equipment reliability.

We trust that the information provided herein adequately supports our request, however, should you have any questions or should you need to discuss this matter further, please contact this office.

Very truly ycurs, Vermont Yankee Nuclear Power Corporation g _ /Ab 1 $*- .

Warren P.)durp Senior Vice Preside Op rations cc: USNRC Region i Administrator '

/p ,_' '

g '

USNRC Resident inspector VYNPS '

USNRC Project Manager VYNPS STATE OF VERMONT )

i ) SS WINDHAM COUNTY )

l Then personraty appeared before me. Wr ren P. Murphy, who, belno duty sworn, clu state that no is Sen!or Vice President, Operations of Vermont Yankee Nuclear Power Corporation, that he Is authorized to exe6te and file the foregoing document in the name and on 100 bonall of Vermon!

Yankee Nuclear Power Corporation and that the statements therein are Itue to the best of his knowledge and beltuf.

~

Sal!y A. Sd.dstrum Notary Public My Commission Eroirm February Io,1995

o.

VYSPS 2.5 LIMITisG CONDITIONS FOR OPERATION 4.5 5JRVEILtAhCE AEQUlFEFEr415 ,

3. If the requirements of Specification 3.5.G .

cannot be cet. an orderly shutdown shall be ,

initiated and the reactor pressure shall oe reuuced to 120 psic within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

i. Minimum Core and Cont ainment (ooling Sys tem H. Minimum Core and Centsineetit Cooling System Availability Ayallability

1. During any period when one of the standby 1. When one of ine stancby ciesel generators is diesel generators is inoperable, centinued rade or found to be inoperable. the remaining reactor oper. tion is permissible <11y during diesel generator shall have been or shall be the succeeding seven days, or the succeeding demonstrated to be operable within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

fourteen days for a one-time extended maintenance activity for the *S' i tandby diesel generator during Cycle 16. provided that all of the Low Pressure Core Cooling and Containment Cooling Subsystemi cor.necting to the aperable diesel generator shall be operable. If this requirement cannot be met.

an orderly shutdown sh&1l be initiated and the reactor shall be fa. the cold shutdown candition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

2. Any ccmbination of incperable components in the Core and Containment Cooling Systems shall not defeat the capability of the remainine operable components to fulfill the core and gy ,

contain=cnt cooling functions.

ou "i3 3. When irradiated fuel is in the reactor vessel 3jj ar.d the ' reactor is in the cold shutdown gg . condition. all Core and Containment Cooling ens Subsystems may be inoperable provided oc work

• • 15 permit 6ed which has the potential for

' Ojj draining the reacto: vessel.

8 35 s o-*

140s

'N Amendment No. 27. 114 94

Ydi!O!oNT YANK 1.fgy n u m mmunenes #

s NUOLEAlt Pownst ColtpostATioN: LAttacha nt 4 f

"" .o*

e, .,

?

• • 4 l

. t t'if y Nodd. Ofdt!!etbOf D yI d>301 700f 7 nac.y p,v,_,4 h ; ,

d y '*)) g' .

., , [*~ ,

-- Q . ,, ...

June J.1992 - ,

BW 92 -068 ,

i United States Nuclear Regulatory Commission Region 1 Administrator 475 Allendale Road King of Prussla,PA 19406

References:

(a) Ucense No. OPR 20 (Docket No. 60 271) .

(b) NRU Memorandum frum T.E. Mustey, Olvec.or, Office of Nuclear Reactor-Regulation, ' Temporary Walvers of Compilance', dated 2/22/90 9

Dear Sir:

9Jbject: Hoquest for Temporary Walver of Compilence from Technical Specific 8tlen LCO ~

Haquirements Portaining to Emergency Olesel Generetor The purpose of this letter is to document our request,in accordance with the guidance provided in Reference (b), for a temporary waiver of compliance from Technical Specification 1.CO requirements -

for Emergency Diesel Generator operability.

[ 1. Reaultements to be Waludi Vermont Yankee Technical Specification 3.5.H.f states the following:

During any period when one of the starxiby diese' ponerators is inoperable, cominued reactor ' l operation is permissible only during the succeeding seven days, provided that all of the 1.cw Pressure Core Cooling and Containment Cooling Subsystems connecting to the operab e diesci ! >

generator shell be operable, if this requiremerit cannot be met, an crderty shutdown shall be -

Initiated and the reactor shall be in the cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Vermont Yankee it r4 Questing tellef from the 7'd&y Umillog CondlCon for Operat!on of Section ' .;

3.3.H,1 for a period of 1 additiona! dey with an emergency diesel generator (EDG) Inoperable.

The walver would extend the available time to replace enolne components and thorou0hly test the unit prior to a return to operable alstus.

2. O!2pssion of. Circumstance 2 The 'A' Emergency Diesel Generator was declared inoperable on May 28,1992 at 1240 pm. ,

During a routine monthly EOG surveillance, a proolem was noted with the Jacket coolant system and the_EDG was therefore declared inoperable pending investigation into the cause of the

- aono,matilles,- Upon d!sassembly of the diesel engine, the #7 cylinder ilner was found to have

^-M O M4035 M 20603 j Prm AfirtCK 00000271 f gj_

a 5

ry N' - u -  :--,>- m ,- -, N w v.w. .e , g e .. Nr

- ly a - J N,N

, ~ .- . .

.. v C rWON T YA NM tt' Nut ' W POWl'ff t, OW8'Q4 A f 4081 (J.S Nuclear Regulatory Commission i Ju.te 3.1992 Page 2 a chtck. In ad6 tion, further inspection revealed plating damage of the liner and pitting dameye of tne upper oc. ton in the #3 cylinder. These indicationo were in tha combustion area anrj not in the piston weer ring area.

Both liners and the #3 piston will be replaced.

O. ComeensgLqry Aqijgn11 As ,ecvited by Techetical Specifications the alternate EDG was satisf actorily tested and all of the Low Prescure Core Cool'ng and Coittainment Cooling Subsystems connected to this oparable EDG were verifled as operable. Additionally, the Vernon Hydro Station was nottfled of this sit'lation and the dedicated tie-lin6 to Vermont Yankee was verified as being avaHable.

The Station Manager concurred with our requent not to do anything that would jeopardize the tie line availability as well as to notify Vermont Yankes of any change in the tie llrie .matus.

It should be not3d that use of the Vernon tie line is addressed li) ocerating p ocedures and operators are trained in its use.

A thorough review cf all planned surveillance actMtles was conducted and only those -

dolcrm!ne'J 'o be of low risk will be allowed. Based upon the short duration of this request, additional allemate testing of the *B* EDG and its subsystems was considered, and determined not to be necessary.

4. Saf ety SLqntricance .gnJLP.,gigntIal Consecurrig,g The proposed one day extension has no impact on the consequences of any previously analyzed event if off site power remains available. The a!!ernate EDO was tested for operability orfor to requesting the Cne-day extension period. This gives assurance that the available EDG would function,if required, in addition, the Vernon tie Ilne, wh!ch has historically dimonstrated l

a veiy high fellability,is availab's to supply power to the emergency bus. The fecuiremets of the Technical Specifications also require that during the one. cay extension period, all-remaining Low Pressure Core Cooling and Containment Cooling systems connected to the l- operable EDG will remain operable. The proposed change would allow the *A* EDG to remain l InoperaDie for one additional day. Any accioent which could occur during this one day period could have occurred in the previous seven day period also. Therefore, the proposed change does not significantly increase the probability of an accident._ Since lhls is an estension of only one day, the increased risk associated with an accident during this period is not significant.

Probabillutic Risk Analysts has estimated that the impact on the expected core damage frequency would be changed by less than 1 percent durir.g the eddillonal one day extension >

period.

l l

L l

l

- - - -nn.; __ . - ~~ .+

VI PMON' YANKCI: NUC1.C Ad POWF.H COWPOMATION U.S. Nuclear riagulatory Commission Ju.ie 3.1992 Page 3

5. Ryfjt!&rLof AccV111 The proposed walver of complianco is for one. time appreisi of tractor operation for up to eight (D) days with the EDG inoperable. The current Vermont Yankee Technical Specifications allow reactor operation for seven m days with the EDG Inoperable. Vermont Yankee believes that tne addillonal one day will provide sdicient margin to repair and thoroughty test the EDO without compromising the continued safe operation of the plant, it should be noted that a algnificant portitsn of the extra LCO time would be far "run.tn' of the new components and operability testing. The EDG would be available during this period, but not consider 6d operable.

6. Eig.nifleant Hqrnagonigrgfgg Vermont Yankee has conctuded that the request does-not involvs a significant horarcs consideration la that the (equest would not:

0) involve a significant increase in the probability cr consequences of an accident previously evatusted. As (fiscussed in section 4, a one (1) day extension to an utreedy existing seven m day Umiting Condition for Operation would involve an insignificant increase in the probability of occurrence and consequences of a design basis accident outing the extention period.

0) create the possibility of a new or different kird of accident from those previously evaluated. The proposed change can have no impact on the possibinty of a new or different initiating event. Any previously analyzed event postulated during the one day extension period can be mitigated by the 6ystems powered by the Vernon tie line,

{

0Q invotve a signlucat% reduction in tha margin of safety. As discussed above, approvst of this request involves a?.!nsigolficant reduction in the snargir of safety because of the nvWlabil!!y of othar plant electrical systems and the short durellon of the extension pericd. The enance will have no significant impact on the consequences f.,f any -

accident and will have no impact on any protective boundary, in summary, the walver of compliance would provide 7 norkrocurring, one-time approval of reactor operation for up to an additional cay with the 'A' EDG Inoperable. The walver of compliance would extend the existing Technical Specification LCO through June 5.1992 at 1240 pm. The watver of comp!!ance will allow an add!!!onalone day to repair components and thoroughly test the EDG prior to returning it to service.

The Vermont Yankee Plant Operations Review Committee (PORC) has reviewed this request for a temporary watver of cornpriance and concurs with the determinations prosented.

~ _ . . . ,- -

I VCHMONT YANKEL NUCL L An POWER COHPOR ATION U.S Nuclear Regulatory Commission Ju.to 3,1992 . ,

Page 4 F

7. Environmental ConseQWtaff.3 No ett ironmental consequences will result from approval of this request.

8. @tificq!!on of Statt Vermont Yankee has netlf>J the State of Vermont of the contr,nt of this request and has forwarded a copy of this document to the Vermont Stats Nuclear Engineer.

11is our understanding that this request for a cne day temporary waiver of compliance has been .-

authorized by totecon oit . lune 3,1992 by James O Uriville (i)SNRC) to Donald A. Reid (VYNPQ, We trust that the Information provided adequately supports our tocunst; however thould you have any questions regar#6g this matten, please contact this office.

Very truly yours.

Vermont Yankee Nuclear Power Corporation

/W j H

! Warren P. Murphy //

Senior Vice Presid6nt, Op.fr tio 3 l

l l

cc: USNRC Oocument Control Desk USNRC Olrector, NRR '

L USNRC Ottoctor, Reactor Projects NRR USNRC Director, Offics of Enforcement USNRC Technical Assistant, Retetor Projects, NRR USNRC Resident inspector (VYNPQ USNRC Project Mana0er. NRR VT Department of Public Service l

l l

l 1

' VERMONT YANKEE A""" # "' '

' NUCLEAR PowEn CORPORATION e

., - y- Feery Road. Drutocoro VT M301.foo2 M-0N -

EHGINECRING CFflCE t

f' -

-644WL,e814tef soo oon.unesrso june 29, M2 **"*"'

4 United States Nuclev Regulatory Commission Regional !

475 Allendale Road King of Prustin, PA 19406 Attn: Regional Administrator

References:

a) Licerue No, DPR 28 (Docket No. 50 271) -

b) NF.C Memorandurn from T.E. Murley, Director, Office of. Nuclear Reactor -

Regulatloo. " Temporary Walven of Compl_ lance', dated 2/22/90

Subject:

Request for Temporar7 Walver of Comptluce from Techalcal Specification LCO Requirernents Perialning to Lnergerx7 Diesel Generator ne purpose of this letter is to document our request, in accordance with the guidance provided' in Reference b), tbr a temporsty walver of conspliance from Techalcal Specificarton LCO requirements for Emergeng Die:,el Generator opwability.

1. Erqvlfsmrnt' to be Walmit

'/ermont Yankee Technid Specification 3.5.H.! states:

During any period when one of the standby diesel generators 'is inoperable, contkued reactor operation is permissible Mly during the - -

succeeding seven days, provided that all of 2e Low Pressure Core Coollag and Containme.ut Ccolleg Subsyst$ms connecting to the operable diesel gercrator shall be operable. If this requirement cannot be met, an ordeth shutdown shall be initiated and the re. actor sha!! be in the cold shutd)wo condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Vermont Yarda.t is requesting relief from the 74ay Limiting Condition for Operat!on of Section 3.L11.1 for ' a ptMc4 of 48 additional hout 'with an' emerr,ca:y diesel. generator. (EDO)-

inoperable. - De wA'ver would extend the av;.ilable fline to replace engine components and thoroughly test tbs unl: prior to r, return to operable status.

F NPDR P EY}Yd6de'92o ADOCK OSo pop.

b 71

_ _ . _ _ _ _ _.- _ = _ _ _ _ _ _ . _ _ . _ . . . . _ . _ _ . _ _ _ _ _ .

,V.S. Nucte.ar lugulatory Couvnluion VCRMONT WNKCC NUrM.L A A POWD1 CCX1PON M cN June 29,1992 Fye:

2. DhttuimuLGrumutanen

he ' A' !!mergeney Diesel Gener.wr wu declared inoper.de on June 23,1992 at 0457 a.m.

During a routine monthly EDG surveillance, the engine tripped approalmatel,v 90 rnlautes [nto its sc.heduled 8 hout run frorn low Jacket coollrig miem ;tessure.

Duc to estensive rework tulict in June to troubitshoot and replace two c)!!nder l(ners, leaking cylinder aQters were considered suspc<t. Aftet an investigation of tarque vajues for adaplvs, lapping of cylinder liner seding surfaces and installationof new gukeu, hydro tests of the. Jacket cooling system failed repeatedly. At this point, cylloder integrity was suspect and it wu found i that the #10 cylinder wu leaking A crack was discovered that originate.t in the threaded adapter connecion in the :ylinder liner. .

Vermont Yankee determined that the most conservative approach to the repalt of this diesel engine was to replace eleven of tt twelve cylinder liners with new Fnproved ilners. The twelfth liner 4 diloder O was replaced a month ago.

3. Comtyputor? Attlana As requhed by Tedtnical Specifications, the a!tenute EDO wu satisfactorily tested and all of the Low Preuure Core Cmilog a..d Containment Cwitng Subsystems connected to this openble EDG were verified a operable. Additionaby, the Vernon Hydro Station wu notitled of this situation and the dedicated tie line to Vermont Yankee was verified as being avahble, ne Station Manapr concurred wim our request not to do anything thu would 'copardLte t.se tie 4fne availability u well u to notify Veimor.t Yrdee of any change in the tieline status.

It should be noted that use of the Vernon tic line is addreased in operating procedures and operators are trained in its use.

A thorough review of all planned surveillance activities was conducted and ordy tbuse determined to be of low risk will Je allowed. Bued upon the shott duration of this request, additional alternate testing of the *D" EDG and its subsystems wu considered, atd deternuned not to be necessary.

4. SafrtY SlenMupce and Potentjal Cordecueneet The preposed 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> catension ha no linpact on the cortequences of any previously an.tlyzed event if o!T ple power remalr's available. The alternate EDG we tested for npendtlity prior to requesting the 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> entension period. This gives Maurance that the available EDG would functirn, if requir.d. In addition, the Verton tie.llne, which has historically dtmonstrated a very high reliability, is available to supply power to the emergency bus. Ti.e requirer'iects of the Tc:Anical Speelfications also require that during the LCO period, all remnlolog Uw Prnsure L Core Cooling and Centalttment Cooling systems connected to the operable EDG will remala operable. The proposed catension would allow tne 'A' EDG to remain Inoperable for 48 ,

additional hours. Any accident which could occur during this 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> period could have occuned to the previous seven4Ay period sjso. *iterefore, the proposed change does not significantly increase the probability of an accident. Stace this is an externion of otuy 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, the increased rist usoelated with an accident during this period is not lgnificant.

ti.5. hicar Xegulatory Cornmtston VEm*04T 'rAMEC NUCL.C AU FOWEr1 CO POM ATM:W ]

q June 29, l'N Pap 3 l

- w

5. (Arnthri of Regtast  :

The proposed walver of compliance is for apprual of reactor operation for up to nine (9) days j~ with the EDO inopstable. De current Vertoont Yankee Technical Spedfi:.itions allow tcJetor -  ;

3 operation for seven p) days with the EDG inoperable. Vennont Yarace belleves that the _ j addition.u 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> will piovide suf0cient matsin to repair aral thoroughly test the EDG without .

compromising the continued safe eneration of the plant. It should be noted that a significant l i

poruen of the extra I CO t!me would be for *rundn' of the new compone.nts and operability testing. The EDG would be aeadable during this feriod, but not coraldered operable.

Pollo ing approximately nins (9) hours of continuo u operation at 70, '15, 57.5 and 100'5 load, it is oui intent to allow the EDO to woldown for b minimum of twelve (12) hours, ,

The return of the 'A' EDO to operable status would taen occur after a succcasful eight (8) hour -

operability run. Follovring restoration of the *A* diesej geaerator to operable s. tus it b our intent to conduct an Additional surveillance test of the 'A* dier.el generator within one week. _

1his testing would be conductett with careful monitoring of key dleal engme parameters to tutther substantiate utisfactory cperation. Additionally,if any signincant, related pro'olems are discovered during these test periods, such that the jacket coollag system problems do out appear i

to be corrected, an orderly shutdown of the plant would be Ini' lated.

7

'the *B* EDG will also be tested far eight hours, after deJaring the 'A' EDG operable, per the e normal mouthly sutveillance procedure.

2

6. SigtillicarlLitmeds Considt!.2MRD [

i Vermont Yankee has concluded that the request does not involve a significant hamds comideration in that the reque.st would not:

(i) involve a significant inercase in the probability or consequences of an accident previously .

• evaluated. As discussed in section 4, a 48 hout esteralen to sn altesdy entsfing seven ,

p) day Limiting Con.dition for Operation would involve an imigniGeant increase la the

. prehability of occurrence -and consequences of a desigt: basis accident during the  !;

extension period. ,

(ii) create the possibdity of a new or different Idad of accident from those previously - l cvateated. 1hc prc. posed change can have no impact on the possibility of a new or - .

i different inittaung event. Any previously analyzed event postutated Juring the 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> -

estettsion period can t>e mitigated by the systems powcM by the Vernon tie line.

involse a significant reduction in the margin of safety. As discussed thove,2 approvaj of I l (iii)

L this requmt involves an iegnificant reduction in the margin of safety because of the-l availability of other plant electrical systems and the shon duration of the exteraion-period, s

in summary, the waiver of compliance would provide approval of reactor operation for up to an ,

addi'iana) 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> with the *A* EDG Inoperable. The waiver of compilance would extend the - -i L

custmg Tectnical Specincation t.C0 through July 2,1992 at 0457 am, ne walver of -

7 l- compliance will ajlow a. .o Stwnal 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> to repair components and thoroughly test the' EDG t prior to returning it to service.

J t-Fe-.-es ge wee =aeeww ri-i e c e - e 4+em>W-4 vee gyg 4 *. ow' 3-+-- w>aws-+-m--=-1e ee-e-#er'r r e sr y' ty+- 4pve+t g- - st -twg-w w=+we'ewevu e-W * =r tm v* e' - " - - e-*"f b--+ 9 w T

• 4

~ - .

f * .

VERMONT YANKEE fWCLC AR POWER COMP 03AT80N U.S. Nuclex Regulatory Cumndssion

' fune 29,1972 ,

, , Page 4 ,

The Vermont Ysakee Plant Operatiom Review Committee (PORC) and Nuclear Safety Audit and - .

Review Committee (NSARC) bave reviewed this request for a temporary walvet of comptlu ,4_ l and concur with the dactminations preuntet. .

7. Environmental Cortsengenca No envirotunental comequnces will result from approval of this request.  ;

8. fgtification of Sista Vermont Yankee has notified the State of Vermont of the content of this request a' ad has forwarded a copy of this document to the Vermont State Nuclear Engineer, it is our understandeg that thlt request for a 48 hout temporary wt.lver of compliance has boca '

authorLcd by telecon on June 29,1992 by James C. Linville (USNRC) to Donald A. Reid (VYNPC'.

We trust that the information piuvided adequately supports out tequest: however should you have  ;

any questions regarding this matter, pleue cocct this office, a

i Very truly yours, Vermon! Yankee Nuclear Power Corporadon

)

$4' '-L - _

Warren P. Mu hy [ . . ('

SenLr Vice F esident. Opet onk

, WPM /dtn cc: USNRC Document Control Dest USNRC Director, NK.R USNRC Director, Atactor Projw. NRR USNRC Director, Office of Enforcement -

USNRC Technical Assistant, Reactor Projc:ts. NRA USNRC Resident inspector, VYNP3 USNRC Project Manager. VYNTS VT Deputment of Public Servlee r

, . - , 9 [wA wh , yE, _ , , 3 - , _ . . .

v: ~~ ,7 _ .

.w.-

i.

,M .

Attachment 6 I

VEI1MONT Y ANKEE l

4 NUCLEAR POWER COI1POIIATION

.z ....

l j

.[

j. NY ,

)

retry nona, eranieborn. vi os 301 7002 s rn'wn'ms'rser -

n , l'i. ).. ,7 '. ' ,',

I i

, ( .'.Q .Ml . . ! ..,.

J July 31,1992 United States Nuclear Regulatory Commission BVY 92 - 94 A'ITN: Document Control Desk j Washincton, DC 20555 i

References:

a. L.icense No. DPR 28 (Docket No. 50 271)

b. leter, USNRC (Tnadani) to NUMARC (Rasin), " Approval of NUMARC

l. Documentation Station Diackout", dated October 7,1988

c. Letter VYNPC to USNRC, BVY 89 36, dated April 12,1989

d. NUMARC 37-00 " Supplemental Questions and Answers", dated December 27,1989

e. NUMARC 874)0 " Major Assumptions", dated Decemixt 27,1989

f. NUMARC letter, " Station Blackout (SDO) Implementation: Request for Supplen.-ntal SBO Submittal to NRC", dated Januarv 4,1990

g. Letter, USNRC (Thadani) to NUMARC (Marion), dated January 3,1990 h, Letter, VYNPC to USNRC, BVY 90 38, dated March 30,1990

i. Letter, VYNPC to USNRC, BVY 91 21, dated February 28,1991

j. Letter, USNRC to VYNPC, NVY 9198, dated June 5,1991

k. Letter, VYNPC to USNRC, BVY 9169, dated July 17.1991

,j l.

m.

Letter, VYNPC to USNRC, DVY 91-88, dated October 1,1991 Letter, USNRC to VYNPC, NVY 92 16, dated F;bntary 21,1992

Subject:

10CFR30.63 Station Blackout (SBO) Response to NRC Request for AdditionalInfomation

Dear Sir:

Dy let'er dated February 21,1992 l Reference (mil, NRC tmnsmitted to Vermont Yankee a list of questions concerning the availability of the Vemon Ilydro Station. Answers to these questions are considered necessary for NRC to complete the SDO review for Vermont Yankee.

/.ttached please find Vermont Yankee's response to Reference (m). Should you have any further questions, please contact this office.

4 Very truly yours, VERMONT YANKEE buCLEAR POWEgCORPORATION

.a. c L c:,1, h%dO.%dkw,h, l#0 nard,A. Tremh!ay, J r.

,. - -7.(g- *1 GC(f.T

- W 5_- - .

Senior Licensing Engineer Att:whment w: USNHC Region i Administrator USNRC Resident inspector -. VYNPS

,:et , : . .: . i st- , , . s. s v ,s

d 0

f Attnehment to 11VY 97.M

/

f Question No.1

/

What provisions are in place or will be put in place to alert the Vermont Yankee nuclear operators if at leuct 2.3 hlW of Vernon Hydro is not available, or couhl no' be made available (within 10 minutes) upon demand?

llesponse The FEllC operating license for the hydro station requires a minimum river flow of 1250 efs. This laJO cfs flow, if passe om.

These provide information regarding the loss of voltage on the tio line, and the too of hydro station generator output for any reason. Even in the run instance where the Vernon Hydro power output is zero, power can still be pmvided by the sepamte 69 kV grid through the Vernon Hydro tic line to Vermont Yui'kce.

The tie linc between the Vernua Hydro station and Vermont Yankee is.normully energized, and the breaker to control connection of the tic lino to emergency buses is under Vermont Yankee control. Connection of Vernon Hydro power to Vennont Yankee emergency buses can be mado directly from the Vermont Yankee control room.

! j 1

i

^ '

^

_.  : I _.

m o

Quesbun No. O If a LOOP and subsequent S110 at the nuclear plant is due to an extensive grid failure which resulta in the acparation of the hydro generation from the grid, what steps and how much tima (realistically under these conditions) would be required by the nacicar plant operators and the operators at the hydro plant to re cnergize the line to We rauclear plans (with required KW available), asstuning (1) that ti,e pre.

existin:: hydro piant load doec nc1 completely acparata from the hydro generation (ie.

the lond emula the hydro ger.aration), and (2) that the pre existing load separates from the hydro gancration?

ltesponso in addressing Station Illackout requirements, Vennont Yankee considered a loss of the 345 kV and 115-kV lines, which constitute the normal offsita power supply. The Vernon Hydo station connects to the 69 kV system, and is not considered a nonnal source of offsite power to Vermont Yankee. It is extremely unlikely for common mode failure of Vernon Hydro and Vermont Yankee's o%ite and onsi'c power to occur-Vernon Hydro station generators are not normally connected the Vermont Yankee emergency buses; the equipment is of different manufacturer; the equipment is maintainod and operated by a separate organization. Vernon Hydru is connected to a 69 kV transmission system which is not directjy electrically connected to Vennont Ynnkco's ohite power sources, thus providing electrical independence and minimizing the potential for common cause failure due to electrical faults, switching problems, or other grid related losses of power. The hydro station is connected to its own switchyard which is physically separated from Vermont Yankee's switchyard (approximately 1 mile), and the transmission lines crnanating from the station are '

ruuted on separate rights of way. The majority of the lines emunating from the hydro station are routed ir completely different directions from the lines supplying olisite power to Vermont Yankco.

['While Vennont theYankee tie linedoes frcmnot Vernon Hydro constitute to Vennont a normal Yankeeload (pre existing) is nonunity energized for the hydro

' station. Since hydro station house loads are inconsequential, the only pre existing loads areseparate station would grid lonos. In the from the grid. Vernon highly unlikely Hydro station has theevent capabilityof black start, and provido power to Vermont Yankee within an hour. Vermont Yankee to a re is considered a priority load in accordance with Vernon flydru Station Operating Ifules.

4

i

( ,

4

. , Question No. 3 ADer the AAC source is connected to the safety bus at the nuclear plant, how will the loads be sequenced on (manually or automatically, kWs vernos timos? For this loading sequence, and assuming a LOOP and SB0 as described above and minimum pre-existing hydro generation, what tests have been or will be made per 10 CFlt 50.63(aX2)(sic) to assure that there will be adequate voltat;c and power availability at the Vennont Yankee safety bus? Provido a descripdon of the tests and any supporting analysis including results if available, or provide the descriptions and a schedule for implementation.

ltesponso '

As discussed in our submittal BVY 9169, dated July 17, 1991, the automatically [w sequenced loads for either emergency bus are less than G00KW. The remaining loads l will be manually sequenced on in accordance with Vermont Yankee's LNP Procedure 5

No. OT 3122. Tests of the Vernon Hydro line are conducted in accoraance with Vermont Yankee Procedure No. OP 4142, "Vernon Tie Surveillance." Plant mode, system operating conGguration, and circuit breaker in'erlocks make it physically impossible to conduct t.hese tests at um full 2.3 MW load anticipated dtuing a station blackout. Vermont Yankeo in evaluating haniware changes that would allow testing at full SBO load. However, there are no plans to perform inercased load testing until the tie line is modified in conjunction with the Vernon Hydro station upgrade, at

! which time testing will be readdressed. (Also, testa required by 10 CFR 50.63(cH2) relate to time, not capacity.)

j

'U[r preliminary load now analysis shows, for conservatively assumed initial l that adequate voltage and power can be made available to the 4160 volt and 480. volt emergency buses. Due to the vintage of the hydro station generators' voltage regulatorn, we cannot at this time analytically predict what the voltage levels will be upon application of the largest load to the 4100. volt bus. However, engineering personnel fmm hydro operations and from central dispatching who are familiar with the operation and responsiveness of the hydro generatms, are confident that these units can power the largest Vermont Yankee load. Additionally, as discutised in our submittal BVY 91-69. Vermont Yankee will be implementing a design change to upgrade the tio line from Vernon liydro. This is scheduled to coincido with the hydm station upgrade. With this equipment in place, we will be able to analytically show adequate voltage and power availability for all Vermont Yankee loada.

J