ML20155E906

Forwards Request for Addl Info Re Util Response to TMI Item II.K.3.5 Concerning Reactor Coolant Pump Trip.Response Requested within 60 Days

ML20155E906
Person / Time
Site:	Millstone
Issue date:	10/06/1988
From:	Jaffe D Office of Nuclear Reactor Regulation
To:	Mroczka E NORTHEAST NUCLEAR ENERGY CO.
References
TASK-2.K.3.05, TASK-TM TAC-49658, NUDOCS 8810130052
Download: ML20155E906 (4)

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OCT o 61989 Docket h'o. 50-336 Mr. Edward J. Mroczka Senior Vice President Nuclear Engineering and Operations Northeast fluclear Energy Con pany P. O. Box 270 Hartford, Connecticut C6141-0270

SUBJECT:

MILLSYONE NUCLEAR POWER STATION, Uh!T N0. 2, REACTOR COOLANT PUMP TRIP (FCP) (TAC h0. 49658)

We are in the process of review'ng your response concerning the post-accident trip of the RCPs (THI Action Item II.K.3.5) for Millstone Unit T.

In order that we r ay ctrplete our revicw, we request that ycu respond to the enclosed request for additional infomation within 60 days following receipt of this letter.

The reporting and/or recordic>eping requirerents contained in this letter affect fewer than 10 respondents; therefore, CFB clearance is not required unde r P. L. f 6-511.

Sincerely,

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David H. Jaffe, Project l'anager Project Directorate I-4 Division of Reactor Projttts I/II

Enclosure:

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Mr. Edward J. Mtoczka M111stene Nuclear Power Station Northeast Nuclear Energy Coepany Unit Nc. F l

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Gerald Garfield, Esquire R. M. Kacich, Manager Day, Berry and Howard Generation Facilities Licensing Counselors at Law Northeast Utilities Service Coepany City Place Post Office Box 270 Hartford, Connecticut 06103-3499 Hartford, Connecticut 06141-0270 W. D. Rotberg. Yice President D. O. Nordquist Nuclear Operat"ons Manager of Quality Assurance Northeast Uti19 ties Service Corpany Northeast Nuclear Energy Conpany Post Office scM 270 Post Office Box 270 Hartford, Conntcticut 06141-0270 Hartford, Connecticut 06241-0?70 Kevin McCarthyu Director Regional Adn.inistrator Padiation Control Unit Region I Ctpartrent of l'nvironnental Protection U. S. Nuclear Regulatery Corrissicn State Office toilding 475 Allendale Read Hartford, Connt eticut CC106 King of Prussia, Pennsylvar.fa 10406 Bradford S. Chise. Under Secretary First Selectren Energy Civisitr1 Town of Waterford Office of Policy and Managerert Hall of Records 80 Washingtcn Ltreet POO Boston Post Road Hartford, Connt.cticut 061Cf Waterford, Connecticut 063PE S. E. Scace Station Superintei.dtr.t W. J. Payrend, Pesider t Inspector M111stor.t Nuc1t<ar Power Staticr Millster.e Fuclear Power Station fcrtheast Nucleat Energy Ccrpany c/o U. S. Nuclear Regulatory Coerission Post Office Bor 128 Post Office Box B11 Waterford, Contecticut Of3E5 Niantic, Connecticut C6357 J. S. Keeran, tinit Superintendent Charles Erinhnan, Manager Millstone Unit No. F Washington Nuclear Operations Northeast Nucitzar Energy Corpany C-E Power Systens Post Office for 128 Combustion Engineering Inc.

Waterford. Cont'ecticut 06385 7910 Wcodmont Avenue

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ENCLOSU3 RE,(UESTFORADDITIONAL_INFORMATION MILLSTONE UNIT 2 REACTOR COOLANT PUMP TRIP DOCKET NO. 50-336 Northeast Nuclear Energy Company's (NNECO's) response to Generic Letter (GL) 86-06 for Millstone, Unit 2, was contained in References 1, 2 and 3.

The informationsuppliedinthesesubmittalsprovidedthebasisofthereviewby the NRC staff and their consultant, EGAG Idaho, Inc.

M111stene Unit 2, is a Combustion Engineering (CE) plant, and in their submittals NNECO stated it endorsed the CE Owners Group (CEOG) reports agd the 4

trip two pumps / leave two punps (T2/L2) strategy developed by the CEOG NNECO trips the first two pumps if the primary system pressure drops below 1600 psia. However subcoolingdropsbelow30'F.the second two pumps are tripped if the primary system Use of a single setpoint, subcooling, to trip the second two pumps is different than the recomendations of the CEOG in References 4 and 5.

The CEOG stated in these references that a criterion for tripping the second set of pumps based on two parameters was reouired in order to distinguish between small break loss-of-coolant accidents (SBLOCAs), where purp trip is required, and non-LOCAs where it is desirable to keep the purps running.

In Reference 3, NNECO stated that for some steam generator tube ruptures ($3TRs) the second set of pumps will be tripped because prinary subcooling would be lost.

NNECO argued this was acceptable because the punps are not required to mitigate a SGTR.

In addition, during a conference call on March 23, 1988 between NNECO, the NRC staff, and EG&G Idaho, NNECO stated that the SGTRs for which the pumps would be tripped included the design basis SGTR (onetube).

The fact that tne second two pumps would be tripped at Millstone, Unit 2 during the d SECY-82-475.gsignbasisSGTRcontradictstheNRCrequirementsstatedin SECY-82-475 states, "The resolution provided in the enclosures

[GenericLetter83-10)isintendedtoensurethatforwhatevermodeofpump i

operation a licensee elects, a) a sound technical basis for that decision exits, b) the plant continues to meet the Comission's rules and regulations,

)

i and c) as a minimum, the pumps will remain running for those non-LOCA i

transietts and accidents where forced convection cooling and pressurizer pressure control would enhance plant control. This would include steam j

generator tube ruptures up to approximately the design basis event (one i

tube)." Thus the use of the single parameter to trip the second two pumps at Millstone,Unh2,doesnotmeettheNRCstaffrequirementthatthepurps remain running for the design basis steam generator tube rupture.

The staff considers that a second parameter is required to make the approach acceptable.

_m..,_.,

_2 In summary, the use of NNECO of a single parameter to trip the second set of pumps at Millstone, Unit 2, is not consistent with the CEOG position that two parameters are required to distinguish between SBLOCAs and non-LOCAs.

It also does not meet the NRC staff requirement in SECY-82-475 that the pumps remain running for the design basis steam generator tube rupture event. The licensee is required to justify this inconsistency to the CEOG position using approved analytical methods or propose acceptable alternatives.

References:

1.

Letter from J. F. Opeka, Northeast Nuclear Energy Cospany (NNECO), to A. C. Thadani (USNRC), "Response to Generic Letter 86-06, Manual Trip of Reactor Coolant Pumps." NNECO letter No. B12313. November 13, 1986.

2.

Letter from E. J. Mroczka (NNECO) to USNRC, "Response to Ger.eric Letter 86-06, Additional Information on Manual Trip of Reactor Coolant Pumps," NNECO letter No. B12395, January 9,1987.

3.

Letter from E. J. Mroczka (NNECO) to USNRC, "Millstone Nuclear Power Station Unit No. 2. Additional Information en Reactor Coolant Pump Trip (TAC No. 49658)," March 3,

1908, 4

Combustion Engineering Nuclear Power Systems Division.

"Justification of Trip-Twe/ Leave-Two Reactor Coolant Pump Trip Strategy During Transients," (Prepared for the C-E Owners' Grcup) Combustion Engineering report CEN-268, March 1984 E.

Corbustion Engineering Nuclear Power Systens Division.

"Response to NRC Recuest for Additional Infernation on CEP-268," (Prepared fo-the C-E Owners' Group) Combustion Engineering report CEN-268 Supplement 1-NP. November 1964, 6.

W. il. Dircks. Executive Director for Operations USNRC, "Staff Resolutien of the Reactor Coolant Pump Trip Issue."

j SECY-82-475, NRC Accession Number 8306030370, November 30, 1962.

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