ML18065B040

Summary of 961016 Meeting W/Utils in Rockville,Md Re 10CFR50.46 Large Break loss-of-coolant Accident Evaluation Model Error & Changes.W/List of Attendees & Handouts

ML18065B040
Person / Time
Site:	Millstone, Palisades, Kewaunee, Harris, Saint Lucie, Robinson, Comanche Peak
Issue date:	11/05/1996
From:	Donohew J NRC (Affiliation Not Assigned)
To:	NRC (Affiliation Not Assigned)
References
TAC-M96355, NUDOCS 9611070139
Download: ML18065B040 (38)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555--0001 November 5, 1996:

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LICENSEES:

TU Electric Carolina Power & L ight'.Company.,

WiScons in Pub 1 i c Servi c.e C(>r'porat for{' ~ *. '"

Northeast Ut i1 it i es Ser\\'i ce Company~ *

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Consumers Power Company * :

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Carolina Power & Ligh't:Cbmpan.Y,,_.. *.:*,,*.** '

Florida Power and I i.ght Company <.'

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FACILITIES:

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Comanche ~eak Steam ;~_l et;:~:tt~:~s.taJ!.<m\\.,U_~its.i.:* an~,. 2.".1 ;.

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SUBJECT:

H. B. Robrnson Steam,Electr-1 c Pl ant,* Un,1 t 2.

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Kewaunee Nuc 1 ear Power* 'praht, ** *. *:'.. * ~*

• Mi 11 stone Nuclear Power *station*,.. Un it* 2 <.

Palisades Plant

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Shearon. Harris* Nuclear Power Plant;. Un it '.J. *" ' *.

St~ Lucie Plant, Unit I

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• MEETI~G ON THE 10 CFR. 50.46~LARGE;BB~A~ LosS~OF-COOLANT

• .ACCIDENT EVALUATION MODEL ERROR AND 'CHANGES/(,TAC NO. M96355)

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. A meeting was held on Wednesday, October 16, 19~6, at the request of the.

• Nuclear Regulatory Commission (NRC) staff, for. the licensees of the eight pl ants. listed above. to present the. resuJ ts. of the licensees' assessments of*

• the impact qf th~-e~ror in the Siemens Power Corporation (SPC) evaluation model on the pe~k cladding temperature (PCT) for the *large break loss-of-

. coolant accident (LBLOCA), and the corrective actions and compensatory measures that have been taken, both short-term and long-term, to assure plant compliance with 10 CFR 50.46.

The meeting was held at NRC headquarters in Rockville, Maryland, with* representatives of the seven licensees. Carolina Pow.er & Light Company is the licensee for both H. B. Robinson, Unit 2, and Shearori Harris, Unit 1.

Attachment 1 is the list of attend~es. Attachment 2 is the handout provided by the NRC staff. This handout contains *the agenda for the meeting, the current status of the faGil it.ies.Jnyo.lved,.the background of the technical iss~e con~er~ing.the LBLOCA evaluation model.for pressurized wat~r reactors (PWRs) of the SPC, and the regulatory requirements in 10 CFR 50.46. *

• Attachment 3 are some of the licensee's assessments which were provided duri~g the meeting.

The meeting was conducted for the staff to understand. the licensees' assessments of the impact on plant operation of the error and changes to the LBLOCA evaluation model.

This* summary discusses the information provided by the licensees and the decisions of the staff that were made during the meeting~

• 0.70023 9611070139 961105 PDR ADOCK 05000255

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• BACKGROUND:

The staff approved a LBLOCA evaluation model for pressurized water reactors, for Exxon Nuclear (now SPC)~ in its letter dated July 8, 1986.

In 1991, SPC made changes to the approved model to correct nonphysical behavior in the model related to the calculation of heat transfer coefficients during the reflood phase of an LBLOCA.

The 1986 evaluation model predicted decreasing heat transfer coefficients with increasing reflood rate into the core in the region of l"/sec to 1.77"/sec reflood rate. It is in this region of reflood rate that. the staff has concerns about the LBLOCA evaluation model.

As a result of an August 1995 meeting between the staff and SPC, at SPC facilities in Richland, Washington, with regard to the LBLOCA evaluation model for PWRs, the staff sent a letter to SPC, dated November 13, 1995, which identified issues related to changes in the model used by SPC for PWRs.

In the letter of November 13, 1995, the staff stated that SPC had made changes to the NRC-approved Fuel Cooling Test Facility (FCTF) reflood heat transfer coefficient correlation used in the TOODEE2 computer code and did not properly assess the significance of the code changes.

It appears that the following two major changes were made to the FCTF correlation in the TOODEE2 code:

(1) some nonphysical non-monotonic behavior of the FCTF heat-transfer coefficient correlation with respect to the reflood rate were eliminated and (2) the quench time calculation used in the model, using data from Cylindrical Core Test Facility (CCTF) experiments, was modified.

By letter dated March 13, 1996, the staff requested SPC to.address the changes to the TOODEE2 model and the code errors identified since July 1986.

On June 2, 1996, SPC submitted topical report XN-NF-82-20, "EXEM/PWR Large Break LOCA ECCS TOODEE2 Updates," Revision 1, Supplement 5, which described the updates made to the TOODEE2 computer code since 1986.

The staff has completed its review of this report and has concluded that the proposed LBLOCA-ECCS model (i.e., 1991 model) is not acceptable and the previous approved model (i.e., the 1986 model) has an error in the model.

The staff's letter to *spc dated October 11, 1996, i nc*l udes the summary of conference calls with SPC on October 10 and 11, 1996, on this matter.

The Safety Evaluation by the staff.. on._topical report _XN-.NF..,.a2..,.20 wilLbe issued in the near future.

Because of the staff's conclusions regarding the accepability of the reflood heat transfer coefficient correlation used in the TOODEE2 computer code, a conference call was conducted on Thursday, October 10, 1996, with the l*i censees.

The purpose of the conference ca 11 was to inform each licensee that the staff had found the changes made in 1991 to the LBLOCA evaluation model, which were intended to address problems with the approved 1986 model used by SPC for the LBLOCA and emergency core cooling system analyses, unacceptable.

In addition, the staff indicated that it will not accept LBLOCA analyses using the previously approved 1986 model unless that model adequately corrected the non-physical behavior observed in the reflood heat transfer correlation.

• In the conference call with the licensees, which was followed up by a letter on October 11, 1996, the licensees were requested, in accordance with 10 CFR 50.46(a)(3)(ii), to assess the impact of these model errors and changes and take whatever actions were required to assure compliance with 10 CFR 50.46.

The licensees were also requested to attend the public meeting on October 16, 1996, and present the results of their assessment of the peak cladding temperature for the LBLOCA and the corrective actions and compensatory measures that have been undertaken, both short-term and long-term, to assure plant compliance with 10 CFR 50.46.

In the phone conference calls with SPC or October 10 and 11, 1996, which are documented in the letter to SPC of October 11, 1996, the staff was informed that SPC had changed the reflood heat transfer coefficient correlation in the 1986 LBLOCA evaluation model to eliminate the non-physical behavior of the

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1986 model in the region of_reflood rate that the staff is concerned about (i.e., l~/sec to 1.77"/sec). The change was to cap the heat transfer coefficient at its value for 1.77~/sec reflood rate. This prevents higher coefficients in the reflood region of concern, and, therefore, the heat transfer coefficient will not decrease with increasing reflood rate (i.e.,

non~physical behavior) within the region of reflood that the staff is concerned about.

Capping the heat transfer coefficient in the 1986 model at the 1.77"/sec reflood rate is referred to in this summary *as '-the "modified 1986" model.

Prior to this meeting, th~ staff was informed that several licensees had performed new LBLOCA analyses with this modified 1986 model.

MEETING

SUMMARY

The agenda is in Attachment 2:

The staff began the.meeting with an introduction that included the information in the Background ~bove. The staff also discu~se4 the background information and the regulatory requirements of 10 CFR 50.46 that is provided in.

The licensees provided-thei~ assessments of the imp~ct of the.~valuation model error and changes on their plants.

Some of this information was provided in handouts in the meeting and-~re included*in Attachment 3.

I Consumers Power Company (Palisades Plant)

The licensee stated that the LBLOCA evaluation model of record for Palisades is the 1991 model; however, the PCT calculated by the 1986 approved model is below 2200 °F and the reflood rates are greater than the region of concern for the staff (i.e., rates greater than 1.77"/sec).

The PCT remains below 2200 °F and plant operation remains in compliance with 10 CFR 50.46.

The licensee concluded that plant operation should remain acceptable to the NRC.

Some of the information was provided in handouts in the meeting and are included in.

• . Carolina Power & Light Company (Shearon Harris. Unit ll The licensee provided a handout which is *included-in Attachment 3.

The LBLOCA evaluation model of record for Shearon Harris, Unit 1, is the unmodified 1986 model and the PCT of 1982 °F octurs at a reflood rate of 2.2"/sec which is outside the range of concern for the 1986 model.

The licensee concluded that the plant rem~ins in compliance with 10 CFR 50.46..

Northeast Utilities Service Company (Millstone, Unit 2)

The licerisee' provided* a ?~Page handoOt ~hich is included.in Attachment 3.* The licensee stated that the unit is currently shutdown; therefore, the emergency core cooling system (ECCS) is adequate at shutdown to meet 10 CFR 50.46 acceptance criteria.* The.PCT is 1922 °F for the 19~1 model and 1927 °F for the 1986 model.

The modified 1986 model results in an increase in PCT so that the final PCT is 1950 °F.

In accordance with 50~46(a)(3)(ii), this increase is not significant and will be included in the licensee's annual report for changes to PCT.

The reflood rate is in the region of concern'of the staff.

Florida Power and Light Company (St. Lucie. Unit 1)

The.licensee stated that the LBLOCA evaluation model of.,record for St. Lucie, Unit 1, is the 1991 model; however, the reflood rate is at the upper range of concern of the staff.

• The PCT previously reported is 1912 °F and the new assessment (the modified 1986 model) has the PCT increased to 1939 °F.

The licensee concluded that the-unit was in compliance wit~*1o~cFR 50.46 and there should be no concern about the unit continuing to operate.

TU Electric (Comanche Peak. Units 1 and 2)

• The licensee stated that Unit 1 was shutdown and Unit 2 was 6 months into the operating cycle.

The LBLOCA evaluation model of record for Units 1 and 2 is the 1986 model, which the licensee had obtained from SPC.

The reflood rate for both units is 1.74"/sec which is within the range of the staff's concern.

The licensee assessed the impact to the PCT for Unit* 1 with a reflood heat transfer coefficient no greater tha~ the value for 1.77"/sec (the modified 1986 model).

The*licensee.*also compared*the 1986model to the 1981 Westinghouse Electric Corporation (W) LBLOCA evaluation model previously used for Unit 2 and stated that both models have similar degrees of conservatism.

The licensee stated that the units were in compliance with 10 CFR 50.46.

Wisconsin Public Service Corporation (Kewaunee Plant)

The licensee stated that the plant is shutdown and is not expected to operate before December 1996.

The assessment of plant operation with respect to the staff's concerns about the 1986 and 1991 models will be made before the startup of the plant and reported to the staff.

" Carolina Power & Light Company (Robinson, Unit 21 The licensee provided a handout which is included in Attachment 3.

The licensee stated that Robinson, Unit 2, is expected to restart from its refueling outage by October 17, 1996.

It may go critical the evening of October 16, 1996.

The LBLOCA evaluation model of record for Robinson, Unit 2, is the 1991 model and the PCT occurs at a reflood rate of 1.74"/sec. The

• licensee reported that the PCT is 2064 °F for the 1991 model and 2157 °F for a modified 1986 model.

• The,*licensee stated that~the.modified 1986 model demonstrates compliance with 10 CFR 50.46 for power operation up *to 87 effective full power days.

The compliance was demonstrated based on changes to the core power peaking factors for plant operation.

After the.licensees' presentations were completed, the staff explained that it had two* concerns.. One concern was the nonphysical behavior in the 1986 model fo~ the range of 1.0"/sec to 1.77"/sec reflood rate where the heat transfer coefficient peaked and decreased in value; This behavior was contrary to experimental data.

The second concern was that in this range, the 1986 model did not appear to predict conservative h~at transfer coeff~cient.

The licensees stated that the data from SPC did show that the 1986 model should predict conservative heat transfer coefficients even* with the nonphysical behavior.

SPC stated that it does not have any new experimental data that it has not already provided to the staff; however, it believes it has new analyses of the experimental data that the staff has not considered.

SPC stated that'the-1986 model does predict conservative heat transfer coefficients for the range of reflood rates of concern to the staff.

SPC presented a graph of:measure~ heat transfer coeffi~jents and the predictions by the 1986 model which showed the coefficient predictions* by the 1986 model should be ~onservative. The'graph was for a reflood rate of 1.74"/sec. This graph was submitted to the staff in a.proprietary 1 etter from SPC dated October 14; 1996.

The staff caucused._ Based on the.caucus, the staff stated that it was satisfied with the presentations by the licensees for the plants involved, and, based on what the licensees have stated that the licensees with operating plants had taken those actions required by 10 CFR 50.46 to allow continued operation.

The licensees for Kewaunee and Millstonei Unit 2, had stated that they would address this issue prior to the restart of the units.

The staff also stated that this meeting should not be considered to satisfy the reporting requirements in 10 CFR 50.46 on changes to the LOCA evaluation models.

• The staff continued the meeting by stating that it was not, at this time, either approving or rejecting the model being used by the licensees to assess compliance with 10 CFR 50.46.

The regulation allows licensees to implement changes to the evaluation model without staff approval.

The staff noted thatthe licensees are primarily basing their judgements on the modified 1986 model which caps the heat transfer coefficient at the 1.77"/sec reflood rate to correct for the nonphysical behavior.

The staff requested that the licensees formally submit the information that they are relying on to assure themselves that the 1986 model is conservative.

SPC had presented a graph of experimental*data and*the heat*transfer coefficients predicted by the 1986 model were shown to be conservative to the experimental data.

The graph is not part of this meeting summary because the data is considered proprietary [the public meeting had been adjourned to reconvene as a proprietary meeting] and this meeting was not intend to be the means for the licensees to present new information for the staff's review of the 1986 model.

The staff caucused again.

Based on the caucus, the staff stated that it considered the graph shown as new information although it did not understand why the conservatism of the 1986 model had not been previously conveyed to the staff in the topical report it had. been. reviewing up *.. to.. October 1996.

Although, it noted that the graph was only for the reflood rate of 1.74"/sec and the range of concern fo~ the 1986 model is from l"/sec to 1.77"/sec. The staff indicated that further review of this and other information would be required before a final judgement could be reached.by*.ithe-staff on the generic

~cceptability of the modifi~d 1986 model for LBLOCA calculations over the range of reflood rate that is of concern to the staff.

The staff requested that the licensees submit the new analyses of data on their dockets within* week of' the meeting.

The staff stated that its concerns about the 1986 model are two:fold (nonconservative predictions of heat transfer_coeffitients and nonphysical behavior of the coefficients with reflood rate} and can be treated separately.. The* immediate concern is the possibility-of nonconservativfi predictions.-in the 1986 model in the reg1.on of reflood rate that is of cbncern to the staff.

The licensees caucused with SPC.

Based on the caucus, the licensees stated that they would each submit a letter addressing the new analyses of data and the possibility of nonconservative predictions by Thursday, October 23, 1996, and address the nonphysical behavior of the 1986 model at a later date.

The staff responded that this was acceptable.

The proprietary meeting was adjourn~ 1_

1

~ohew, Sr. Project Manager cJ' ~roject Directorate IV-1 Division of Reactor Project~ Ill/IV Office of Nuclear Reactor Regulation Docket Nos. 50-261, 50-255, 50-305, 50-335, 50-336, 50-400, 50-445, and 50-446 Attachments:

1.

List of Meeting Attendees

2.

NRC Staff's Handout

3.

Licensees' Handout cc w/atts: See next page DISTRIBUTION: **HARD COP-Y fEE-MAIL

"{Q,~R~t. :rrm PUBLIC FM-iragr'fa]J(Thadani R. Zimmerman C. Dawes tiOGC (15Bl8)

J. Dyer, RIV E. Adensam W. Beckner A. Levin B. Mozafari N. Le R. Schaaf R. Laufer OFC NAME DATE COPY

"'*PD4-l r / f B. Sheron G. Hill (2)

G. Holahan G. Thomas D. McDonald T. Polich BC SRXB/DSSA*

TCollins J. Donohew M. Young J. Roe

• "'ACRS D. Murphy T. Collins J. Staudenmeier L. Wiens S. Koenick

0 0 the possibility of nonconservative.predictions by Thursday, October 23, 1996, and address the nonphysical behavior of the 1986 model at a later date.

The staff responded that this was acceptable.

The proprietary meeting was adjourned.

Docket Nos. 50-261, 50-255, 50-305, 50-335, 50-336, 50-400, 50-445, and 50-446 V\\~

ack N. Donohew, Sr. Project Manager Project Directorate IV-1 Division of Reactor Projects Ill/IV Office of Nuclear Reactor Regulation Attachments:

1.

List of Meeting Attendees

2.

NRC Staff's Handout

3.

Licensees' Handout cc w/atts: See next page

TU Electric Company cc:

Senior Resident Inspector U.S. Nuclear Regulatory Commission P. 0. Box 1029 Granbury, TX 76048 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011

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Morgan, Lewis & Beckius 1800 M Street, N.W.

Washington, DC 20036-5869

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• TU Electric Group Vice President Nuclear Attn:

Regulatory Affairs 'Department P. 0. Box 1002.

• Glen Rose, TX 76043

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Mr. William D. Johnson Vice President and Senior Counsel Carolina Power & Light Compa.ny '

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Ms. Karen E.

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Assistant At~orney General State of North Carol foa Post Office* Box* *629*,

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- H. B. Robinson Steam Elettrtc Plant:

3581 West Entrance Road Hartsville; South Carolina 29550_

Public Service Commission

. State of South Carolina Post Office Drawer 11649 Columbfa, *so:uth *carollna - -29*211 Mr. R. M. Krkh.

Manager - Regulatory Affairs Carolina Power & Light Company -

• H. B. Robinson St~am Electric Plant, Unit No.. 2 3581 West Entrance Road Hartsvill~, South Carolina 29550 H. B. _Robinson Steam Electric Plant, Unit No. 2 Mr. Dayne H. Brown, Director Department of Environmental, Health and Natural Resources Division of Radiation Protection Post Office Box 27687

• Raleigh, North Carolina 27611-7687 M~~~Robert P. Gruber Executive Di rector Public Staf( - NCUC

_Post Office Box 29520.

Raleigh, North Carolina 27626-0520 Mr;~Max Batavia, Chief SoUth:Carolina Department of Health

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-~Mr. J. Cowan Vice President Nucle~r Services and Envi~onmental Support Department Carolina Power & Light Company Post Office Box 1551 - Mail OHS7

~aleigh, North Carolina 27602 Mr. Milton Shymlock U. S. Nuclear Regulatory Commission 101 Marietta Street, N.W. Suite 2900 Atlanta, Ga. 3023-0199 Mr~ C.

S~ Hinnant, Vice President**

Carolina Power l Light Company H. B. Robinson Steam Electric Plant, Unit No. 2 3581 West Entrance Road _

Hartsville, South Carolina 29550

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Director.df Site Operations Carolina. Pgwer & Light Company 1i '. "

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.Post Off1ce Box 1551 i'.,.

Shearon~.Harris Nuclear* Power Plant Raleigh, 'North. Carolin.~* 2760,2

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~:New Hi11, North Carolina 27562-0165 Resident Inspector/Harris NPS c/o U.S. Nuclear RegulatoryJori\\mtssion 5421 Shearon Harris Road New Hill, North Carolina 27562~999~

Ms.* Karen E. Long Assistant Attorney General State of North Carolina Post Office Box 629

. Raleigh, North Carolina 27602 Public Service Commission State of South Carolina Post Office Drawer 11649 Columbta, South Carolina 29211 Regional Administrator, Regiorr II U.S. Nuclear Regulatory Commission 101 Marietta St., N.W~ Suite 2900 Atlanta,_.Georgia 30323 Mr.. Dayne H. Brown,* Di rector Division bf Radiation Protection N*. C. Department of En vi ronmenta l Division of Radiation Protection Commerce & Natural Resources Post Office Box 27687 R~Jei_gh, North Ca_roJin.a 27611-7687..

Mr. J. Cowan Vice President Nuclear Services and Environmental Support Department Carolina Power l Light Company Post Office Box 1551 - Mail OHS7

.Raleigh; North Carolin_a*.-'~7602*

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Mr. Robert P. Gruber Executive Director '

Public Staff NCUC Post Office Box 29520 Raleigh, North Carolina 27626 Chairman of the North Carolina Utilities Commission Post Office Box 29510 Raleigh, North Carolina 27626-0510 Mr. T. D. Walt Manager, Regulatory Affairs Carolina Power & Light Company Shearon Harris Nuclear Power Plant P. o*.. Box 165, Mail Zone 1.

New Hill, Nort.h... Caro l i na 27562-0165 Mr. Vernon Malone, Chairman

• Board of County Commissioners of Wake County P. 0. Box 550 Raleigh, North Carolina 27602 Ms. Uva Holland, Chairman.

Board of County Commissioners of Chatham-County P. 0. Box 87 Pittsboro, North Carolina 27312 Mr. Milton Shymlock U.S. Nuclear Regulatory Comm.

101 Marietta Street, N.W.

Suite 2900 Atlanta, Georgia 30323-0199

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Carolina Power & L igh_t Compan'"y cc:

Mr. W. R. "Robins*on'~*-<<.Vice President.. **

Shearon Har-ri s --~u.ci ea*f, Power Pl ant/

Carolina Power & L:ight-.Company.,..,. '

Post Office Box 165*, *Mail Chde:. Zone' 1 Shearon Harris Nuclear Power Plant Unit 1 New Hi 11, NC 275~2-;0_165'.

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• . Electric Unit 10 Liberty Square New Britain, CT 06051 Mr. Kevin T. A. McCarthy, Director Monitoring and Radiation Division Department of Environmental Protection 79 Elm Street

• Hartford, CT 06106-5127 Mr. Allan Johanson, Assistant Director Office of Policy and Management Policy Development and Planning Division 80 Washington Street Hartford, CT 06166 Mr. S. E. Scace, Vice President Nucl~ar Reengineering Implementation.

Northeast Utilities Service Company P.O. Box 128 Waterford, tT 06385 Regional Administrator Region I U.S. Nuclear Regulatory Commission

. 475 Allendale Road King of Prussi-a,*~ PA 19409 First Selectmen Town of Waterford Hall of Records~~-

200 Boston Post Road Waterford, **~T 0638~\\. *

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Charles Brinkman,- Manager Washington Nuclear Operations ABB Combu~tion Engineering 12300 Twi~brook Pkwy, Suite 330 Rockville, MD 2*0852 Mr. E. A°' DeBarba Vice President - Nuclear Technical Services Northeast Utilities Service Company P.O. Box 128 Waterf!>Y'_d, CT 06385 Mr. F. C. Rothen Vice Pres~dent - Nuclear Work Services Northeast Utilities Service Company

• P.O. Box-128 Waterford, CT 06385 Ernest C.

Hadley~ Esq.

1040 B Main Street P. 0. Box --549

• West Wareham, MA 02576 Mr. John Buckingham

_Department of Public Utility Control Electric Unit

.>10 Liberty Square New Britain, CT 06051 Mr. Ted C. Feigenbaum Executive Vice President and

, Chief Nuclear Officer

'~ortheast Utilities Service Company c/o Mr. Terry L. Harpster

.*::Director - Nuclear Licensing Services

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ST. LUCIE PLANT Regional Administrator Region II Jack Shreve, Public Counsel Office of the Public Counsel

~/o The Florida Legislature 111 West Madison Avenue, Room 812 Tallahassee, Florida 32399-1400 -

U.S. Nuclear Regulatory Commission 101 Marietta Street, NW: Suite 2900 Atlanta, Georgi~ 30323 Senior Resident Inspector St. - Lucie Pl ant U.S. Nuclear Regulatory Commission 7585 S. Hwy AlA Jensen Beach, -Flori~a 34957 H. N. Paduano, Manager Licensing & Special Programs Florida Power and Light Company P. 0. Box 140oo-Juno Beach~- *norida 33408-0420 Joe Myers, Director J~ A. Stall, Site Vice President St. Luci~ Nu~lear Plant Division rif Emergency Pr~paredness -

Department of Community-Affairs 2740 C_enterview Drive Tallahassee, Florida 32399-2100-J. -R. Newman

• Morgan, Lewis & Bockius

-1800 M*Street, NW.

Washington; DC - 20036 P. 0. Box 128 Ft. Pierce, Florida 34954-0128 J. Scarola Plant General Manager St. Lucie ~uclear Plant

-P.O. Box 128 Ft_. Pierce, 1flcmida -- *_34954-0128 Mr. Kerry Landis John T. Butler, Esquire_-

Steel, Hector and Davis 4000 Southeast Financial Center.

Miami, Florida *- 331.31 '-2398_-~,.

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U.S. Nuclear Regulatory Commission.

JOI Mariett~ Street, N.W. Suite.2900 Atlanta, Georgia 30323-019~-

Mr. Thomas*-R.L. Kindr~d E. J! Weinkam- -*

County Administr_ator Licensing Manager St. Lucie County'

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~-St. Lucie Nuc 1 ear* Pl ant 2300 Virgin.i_a Avenye

• '>P:o->sox* 128

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Washington Nublea't bp_erationsf *.. ** ;;:

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-~resident - Nuclear Division ABB Combustion* Eng*ineerfog, ~Nu~lear --~

Flor.ida Power and Light Company I

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' P.O: Box 14000 12300 Twinb~~ok"Pa.rkwa/, Suite 33'g.* ',,

': "Ju.n'q_-.Beach, flor.ida 3308-0420 Rockvi 1 le., l Maryl<<rnd ~o_a52' \\;. l

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Rehabilitativ*e** Services**.-

1317 Winewood B_,lv(f,. *. -

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Ta 11 ahas see, Fl.ori~da, 32399.,..0100*

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Consumers Power Company cc:

Mr. Thomas J. Palmisano Plant General Manager Palisades Plant 27780 Blue Star Memorial Highway Covert, Michigan 49043 Mr. Robert A. Fenech Vice President, Nuclear Operations Palisades Plant 27780 Blue Star Memorial Highway Covert, Michigan 49043

.M. I. Miller, Esquire Sidley & Austin 54th Floor One First National Plaza Chicago,_ Illinois 60603 Mr... Thomas A. McNish Vii::e President & Secretary Consumers Power Company

• 212 West Michigan Avenue Jackson, Michi~an 49201 Judd L. Bacon, Esq~ire Consumers Power Company 212 ~est Michigan Avenue Jackson,. Micnigan 49201

• Regional Administrator,' RegJon III Palisades Plant Drinking Water and Radiological Protection Division Michigan Department of Environmental Quality 3423 N. Martin Luther King Jr Blvd P. 0. Box 30630 CPH Mailroom Lansing, Michigan 48909-8130 Gerald Charnoff, Esquire

Shaw, Pitt~an, Potts and Trowbridge 2300* N Street, N. W.

Washington DC 20037 Michigan Department of Attorney General Special Litigation Division 630 Law Building P.O. Box 30212 Lansin*g, Michigan 48909 Mr. Thomas C. Berdine Manager, Licensing Palisades Plant

• 27780 Blue Star Memorial

-t~vert~ Ml. 49043

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Highway U.S. Nuclea~ Regula.tory ~o~nHs~*~on.~....,

801 Warrenv111 e Road

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Lisle, Illinois 60532-4:351

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Office of the Governo.r Room 1 - Capitol Building..,..,.

Lansing, Michigan 4891~ *.

U.S. Nuclear Regulatory Commission..

Resident Inspector's Office.'*

Palisades Plant 27782 Blue Star Memorial Highway Covert, Michig~n 49043 j

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Kewaunee Nuclear Power Plant Wisconsin Pt.iblTc:-s*ervice Corporation cc:

Foley & Lardner Attention:

Mr. Bradley D. Jackson One South Pinckney Street P.O. Box 1497 Madison, Wisconsin 5~701~1497 Chairman Town*of*Carlton Route 1.

Kewaunee, Wisco~sin 54216~.

I Mr. Harold Recke l b~rg; Chai rm~n * \\*, -,_.0.': \\

Kewaunee County Board <. : * -*. ' '

• f Kewaunee County C.ourthouse Kewaunee, Wiscons*tn c, 542~~.'..,.:"

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Chairman

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Resident Inspectors Office :.. '*

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• Kewa~nee, Wis~onsin -54216 Regional Administrator - Region III U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, Illinois *-6_~532-453i Mr. Robert S. Cullen Chief Eng.i neer Wisconsin Public Service Commission 610 N. Whitney.Way Madison, Wisconsin 53705-2729 Mr. M.. L. Marchi Manager - Nuclear Business Group Wisconsin Public Service Corporation Post Office Box 19002 Green Bay,.Wisconsin 54307-9002

ATTENDEES AT THE MEETING OF OCTOBER 16. 1996 LARGE BREAK LOSS-OF-COOLANT ACCIDENT EVALUATION MODEL ERROR AND CHANGES J. Donohew

. B.. Sheron T. Collins W. Beckner A. Levin G. Thomas*

J. Staudenmeier B. Mozafari N. le L. Wiens

. R. Schaaf R. Laufer S. Koenick M. Young D. Murphy C. Ogle M. Killgore R. Walker W. Choe

• J. Kabadi M. Schoppman K. Karcher C.. Hinnant*

R. Krich

- J.. Caves T... Berdine D. Fadel A. Wil 1 i ams D. Wanner M. Van Haltern M. Ehredt_. _

D. Curet.

E. Mi 11 saps S.

Jen~en

.W. Kayser R. Reynolds R. Gottula AFFILIATION NRC/NRR/PDIV-1 NRC/NRR/ADT NRC/NRR/SRXB.

NRC/NRR/PDIV-1 NRC/NRR/SRXB NRC/NRR/SRXB NRC/NRR/SASG NRC/NRR/PDII-1 NRC/NRR/PDII-1 NRC/NRR/PDII-3

• NRC/NRR/PDIII-1 NRC/NRR/PDIII-3 NRC/NRR/PECB NRC/OGC.

~

NRC/Ol,; ;'.'

~.

Tech. Asst. to the Chairman TU El ectr..ic.

. TU Ele'c:tric '

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TU Electric*." ' - '*- ;,

11

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1 :

• ~ Florida Pb\\'(er &.-,L-ight-...~ompany

-.._* * *:....-- 'FloHda' P.ower/& Light 'Company*

';~ -

Carol i.na,Power & ligh.t..,._: ***

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c~r9lin~ !Po~e.r\\ ~,Light,:"":

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Carolina P9wer. &' Light

,'Ca,r9Tina'*Power*&.Ligh;t.;1.-.:;.

1

. ;f 1

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• Consumers ~ow,er, -_Cqmpany',.. **~

~: *

.-C:!Jns*um~~'.: P,.ower :~qmp*any-< :;

• Cons1,,1mer Power _Company :..

'.,:wi~sc~nsjn Puplic**servi~e Corp:

• ".**Northeast Uti l iti~.s '">

~ *

"... '. ',* Northeast Utilities **

.,:l "

sremeris* Power corporation*

~- <<' *

. *"Siemens Power Corporation Siemen~~Po~er Corpo~ation 1**

Siemens Po*wer Corporation

,. Siemens "Power Corpor;-at ion Si~mens Power Cprporation

-*~

NRC

= Nuclear Regulatory Commission NR~

= Office.of Nuclear Reactor Regulation OGC

= Office of the General Counsel 01

= Office of Investigations PDXX-Y = Project Directorate XX-Y SRXB

= Reactor Systems Branch PECB

= Events Assessment and Generic Communfcations Branch SASG

= Analytical Support Group ATTACHMENT 1

AGENDA MEETING OF OCTOBER 16. 1996

• LARG[ BREAK LOSS-OF-COOLANT ACCIDENT CODE MODEL ERRORS

2.0 BACKGROUND

/50.46 REGULATION REQUIREMENTS 3.0 LICENSEES' PRESENTATIONS 4.0 NRC STAFF CAUCUS 5;0 NRC STAFF

SUMMARY

Plants Involved:

Paltsades Plant Robinson St~am Electric.Plant, UNIT 2

. Kewaunee Nuclear Power Plant ST. Lucie Plant, Unit 1

• Millstone Nuclear Power Station, Unit 2 Shearon Harris Nuclear Power Plant, Unit 1 Comanche Peak Station Units 1 and 2 NRC Staff NRC Staff Licensees Docket nn. 50-255 Docket No. 50-261 Doc~et ~o. 50-305 Docket N~~ 50-335 Docket No. 50-336 Docket No.

50~400~

Docket No.s 50-445 and 50-446 ATTACHMENT 2

r October 16, 1996 STATUS OF PLANTS AFFECTED BY THE SIEMENS LBLOCA MODEL ERRORS AND CHANGES PLANT STATUS OF PLANT OPERATION Comanche Peak Units 1/2' Unit 1 shutdown, into 45 day outage, no technical issues to impact restart.

. Unit 2, six months into operating cycle.

Kewaunee Plant shutdown, but has problems with steam generator which may affect startup.

Mil 1 stone Unit 2 Unit shutdown with no date for restart.

Palisades Three weeks before plant shutting down, outage scheduled to last 45 days~

H.B. Robinson Unit 2 Unit shutdown, but scheduled to restart this week. LBLOCA reflood rate is within the affected region, of fl ow.

• .1 Sheron Har~is Unit 1 The,LBLOCA refl ood rate is greater than the affected reflood region for the LBLOCA model~

until after PCT is reached.

St. Lucie Unit 1 Unit is three months into the current operating cycle. Unit started up in July 1986.

LBLOCA = large break loss of coolant accident PCT

= peak cladding temperature

' 1..

MEETING WITH LICENSEES USING

• s*IEMENS LBLOCA EM OCTOBER 16, 1996 BACKGROUND AND REGULATORY REQUIREMENTS TIMOTHY E. COLLINS ACTING CHIEF

. ]REACTOR.. SYSTEMS BRANCH DIVISION OF SYSTEMS SAFETY ANO ANALYSIS.

1

Siemens PWR LBLOCA Ev*a1uation Model July 1986

~'

NRC Staff approves Siemens (Exxon at the time of approval) l~BLOCA *Evaluation Model.

August 1991 Siemens made changes to their LBLOCA Evaluation Model to correct unphysical behavior.

August 1995 NRC staff noted significant changes in PCT resulted from the 1991 model changes during a review of software development records and calculation files.

January 1996

...,5.iemens. pre.sents.changes to their Evaluation Methodology at a public meeting at NRC Headquarters.

2

.)'

.~

March 1996 NRC staff requests that Siemens submit the changes to the EM for review by NRC staff.

June 1996 Siemens submits the changes to the EM for review.

July 1998 Siemens provides estimate of net PCT impact of the f;hanges for all plants.

August 1996 Siemens provides supplementary information. -

NRC staff documents concerns in RAls. -

September 1996

• Staff decides that the inform1tion provided by Siemens Is_ not adequate to.support the 1991-changes.

3

J.

~asis of Rejection of Model Changes

1) Nonphysical behavior of HTC vs. reflood rate.

2) Insufficient data in the range of concern to demonstrate conservatism.

• 3)' Use of new quench time methodology has not been supported by data comparisons.

4

. )

I

.J unphysical I

reflood veloclty Behavior of heat transfer coefficient with respect to ref lood velocity 5

4 450r----,------,-----r---~---- 79.25 400 Aun 31203, 38.4 mm/sec (1.51 in./sec)

Aun 31302, 76.5 mm/sec (3.01 in./sec)

-- Aun 31504, 24.6 mm/sec (0.97 in.Isac)

-*- Run 31701. 155 mm/sec (6.1 inJsec) 350

-*- Run 31805, 20.6 mm/sec (0.81 inJsec)

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300

/*

~250 I r'

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~200; (

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=..

I 76

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70 60 f 50 1

-i *o 40 =

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30

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20 I 10 00~-----:-;100~-----200~....;_--~300~------~----___.~

Time (He)

Figure 6.4-9.

Flooding rate effect on FLECHT heat transfer (midplane elevation).

Behavior of heat transfer coefficient with

• ~

• respect to reflood velocity observed in FLECHT experiment (figure from NUREG-1230, "compendium of ECCS Research for Realistlc LOCA Analysis).

6

REGULATORY REQUIREMENTS 10 CFR 50.46(a)(3)(ii) STATES:

"FOR EAC.H CHANGE TO OR ERROR DISCOVERED IN AN ACCEPTABLE EVALUATION MODEL OR IN THE APPLICATION OF SUCH A MODEL THAT AFFECTS THE TEMPERATURE CALCULATION, THE APPLICANT OR LICENSEE SHALL REPORT THE NATURE.OF THE CHANGE OR ERROR AND ITS ESTIMATED EFFECT ON THE LIMITING ECCS ANALYSIS TO THE COMMISSION AT LEAST ANNUALLY AS SPECIFIED IN 50.4. IF THE CHANGE OR ERROR IS SIGNIFICANT, THE APPLICANT OR LICENSEE SHALL PROVIDE THIS REPORT WITHIN 30 DAYS AND INCLUDE WITH THE REPORT A PROPOSED SCHEDULE FOR PROVIDING A REANALYSIS OR TAKING. OTHER ACTION AS MAY BE NEEDED TO SHOW

. COMPLIANCE WITH 50.46.REQUIREMENTS....

• *.. ANY CHANGE OR ERROR CORRECTION THAT* RESULTS IN A CALCULATED ECCS PERFORMANCE THAT DOES NOT CONFORM TO THE CRITERIA SET FORTH IN PARAGRAPH (b) OF THIS.

SECTION IS A REPORTABLE EVENT AS DESCRIBED IN 50.55(e),

50.72, AND 50.73. THE AFFECTED APPLICANT OR LICENSEE SHALL PROPOSE IMMEDIATE STEPS TO DEMONSTRATE COMPLIANCE OR BRING PLANT DESIGN OR OPERATION INTO COMPLIANCE WITH 50.46 REQUIREMENTS."

10 C.FR S0.46(8)(2) STATES:

. "THE DIRECTOR OF NUCLEAR REACTOR REGULATIONS MAY IMPOSE RESTRICTIONS ON REACTOR OPERATION IF IT IS FOUND THAT THE EVALUATIONS OF ECCS COOLING PERFORMANCE SUBMITTED ARE NOT CONSISTENT WITH PARAGRAPHS (8)(1 )(I)

AND (Ii) OF THIS SECTION."

7

LICENSEES' PRESENTATIONS AT THE OCTOBER 16, 1996, MEETING ON THE SIEMENS' LBLOCA MODEL ERROR AND CHANGESr Consumers Power Company Carolina Power & Light Company Northeast Utilities Service Co.

Florida Powe~*& Light Company

• Pa-1 i sades Pl ant H.B. Robinson.Steam Electric Plant, Unit 2 Shearon Harris Nuclear Power plant, Unit 1 Millstone Nuclea~ Power Station, Unit 2 St. Lucie Plant, Unit*1 f-.~

ATTACHMENT 3

INTRODUCTION We understand that the concern focuses on modeling of heat transfer coefficients corresponding to reflood rates between 1.0 in/sec and 1.77 in/sec in the 1986 model

.. and we ~nderstand the 1991 model is unacceptable.

We propose to have each utility present its own position relative to the NRC identified area of concern. Please recognize that individual utilities may have inclu.ded data in their analyses associated with the 1986 model that the NRC has not yet had an opportunity to review. If these details are required at this time, proprietary information would be needed. Otherwise, we will use only non-proprietaryinformation.

PALISADES ASSESSMENT As a result of the October 1 O conference call, Palisades personnel initiated an internal Condition Report (C-PAL-96-1160) in order to address the NRC concerns. Siemens communicated its engineering judgement to Palisades following the conference call, and provided written confirmation later that evening. Our conclusions are:

1. Correction of the model deficiencies is not expected to cause predicted peak

. clad temperature (PCT) to exceed the 1 OCFR50.46 limit of 2200°F, an.d all of the 1 OCFR50.46(b). criteria are expected to be satisfied.

2 1

• Initial assessment for.Palisades is that our reflood rates are outside the NRC region of interest during the time period when PCT is approached.

3. The 1991 model (Palisades model of record) predicted a PCT of 1862°F, with the previously approved 1986 model predicting a -PCT of *1882 ° F. Since Palisades reflood rates are outside the region of concern, we believe that the.

HTCs used in the 1986 model is acceptable for Palisades.

The above judgements collectively support the assessment that PCT would not exceed 2200~F with the moq~I deficiencies correct_eq. As a result of t_he a~ove judgements, Palisades decided that plant operation is within 10CFR50.46 limits and continued operation is allowed.

In order to completely resolve. this issue, Palisades will work with Siemens to ensure that the LBLOCA analysis for Palisades is fully accepted by NRC. Palisades will continue to assess this subject and will take appropriate and conservative actions to ensure that Palisades remains within the limits stated in 10CFR50.46.

Carolina Power& Light Large Break Loss of Coolant

• Accident (LBLOCA) Evaluation Model Resolution John R. Caves Project Engineer-Press;l.Jrized Water Reactor Fuel, Nuclear Engineering Department t

f

Harris Resolution Status e Analysis of Record (AOR) used Siemens Power Corporation (SPC) 1986 Evaluation Model submitted per 1 OCFRS0.46. Letter dated September 11*, 1996.

/qA

• Limiting Peak Clad Temperature (PCT) of 1982°F occurs at reflood rate of 2.2 inches per second. This is outside range of concern in 1986 Evaluation Model.

• Confirmation calculation of PCT using a reflood heat transfer coefficient no greater than that corresponding to a reflood rate of 1.77 inches per second de.monstrated no effect on PCT.

eseeep I

t ~

e.

Harris Resolution Conclusion

• Harris remains in compliance with 1 OCFR50.46(b ).

Robinson Resolution Prior Status

• AOR used SPC 1991 Evaluation Model. Letter dated April 24, 1996.

+p++ I

• Limiting PCT*occurs at reflood rate of 1.74 inches per second. This is within range of concern in 1986 Evaluation Model.

I I -~

"1 Robinson Resolution Error Impact F~

.50

.80 57 y++ 'AM

Robinson Resolution Current Status

• 1986 Evaluation Model using a reflood heat transfer coefficient no greater than that corresponding to a reflood rate of 1.77 inches per second demonstrates 10CFR50.46(b) compliance up to 87 Effective Full Power Days.

• 1 OCFRS0.46 notification of a Significant Error in an Acceptable Emergency Core Cooling Model submitted by letter Oftober 14, 1996.

• Revised Core Operating _Limits Report*

submitted by letter October 15, 1996.

• Plant startup expected to occur October 17, 1996.

1¥3M§A'

Robinson Resolution Conclusion

• Further analysis required to support continued operation beyond 87 Effective Full Power Days.

• Final disposition of Evaluation Model discrepancy under evaluation.

{~:

9*

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.~ ~ Northeast

.,, Utilities

. Millstone 2 M. L. Van Haltem Supervisor Thermal Hydraulic Analysis t

I"-,

t

~'"\\_ Northeast Impact of SPC Error

'8!' Utilities Evaluation I

• Millstone 2 is currently shutdown

• 1991 EM PCT - 1922 F

• 1986 EM PCT - 1927 F

• Error ~ PCT - 23 F

-/

• Final PCT

~ 1950 F

• Per 10CFR50.46 (a)(3)(ii) Error is not

" significant. "Will be included in annual report.

)

1*.it, I

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Florida Power & Light St. Luc;ie Unit 1.

LBLOCA Assessment Results:

Current Analysis of Record PCT -

. New Assessed PCT (Change in PCT 27 °F)

==

Conclusions:==

No 10 CFR 50.46 Compliance Issue Reportability in Annual Report No Operability Issue Presented By Jay N. Kabadi Nuclear Fuel Department 1912 °F 1939 Op