ML20046C986

Forwards Rev 16 to Rept, Analysis of Hydrogen Control Measures at McGuire Station, Incorporating NRC 930526 SER Which Closes Subj Issue for Plants.Rept Also Applicable to Catawba Nuclear Station as Noted in Rev 9.W/o Rept

ML20046C986
Person / Time
Site:	Catawba, McGuire, Mcguire
Issue date:	08/05/1993
From:	Tuckman M DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9308130184
Download: ML20046C986 (1)

Text

II I DukePowerCompany ' M S Tttuta

. - P.0 Bat 2006 Senior VicePresident Osarlone, NC2820H006 NuclearGeneration (704)382-2200 Offtce (704)3824360 Fax l DUKEPOWER August 5, 1993 U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Document Control Desk

Subject:

McGuire Nuclear Station Docket Numbers 50-369 and -370 Catawba Nuclear Station Docket Numbers 50-413 and -414 Revision to Duke Power Company's Hydrogen Control Document

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Attached _ are five (5) copies of Revision 16 to Duke Power Company's report, "An Analysis of Hydrogen Control Measures at McGuire Nuclear Station." As noted in Revision 9, this-report is also applicable to Catawba Nuclear Station. The revision incorporates the NRC's May 26, 1993 Safety Evaluation Report, which_ closes the hydrogen control issue for both stations, into the. document.

If you have any questions regarding this revision, please call Scott Gewehr at (704) 382-7581.

Very truly yours, a S*  % m M. S. Tuckman cc: Mr. V. Nerses, Project Manager

. Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 14H25, OWFN Washington, D. C. 20555 Mr. R. E. Martin, Project Manager Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory. Commission Mail Stop.14H25, OWFN-Washington,.D.'C. 20555 Mr. S. D. Ebneter, Regional Administrator U.S. Nuclear Regulatory Commission - Region II 101 Marietta Street, NW - Suite 2900 Atlanta, Georgia 30323

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308130184 DR 930805 3 l i

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UNITED STATES

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• [ NUCLEAR REGULATORY COMMISSION

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%, ...../ May 26, 1993

-Docket Nos. 50-413, 50-414 50-369, 50-370 Mr. Hal B. Tucker Senior Vice President - .

Nuclear Generation -

Duke Power Company P. O. Box 1006 Charlotte, North Carolina 28201

SUBJECT:

SAFETY EVALUATION - CLOSURE OF THE HYDROGEN CONTROL ISSUE PURSUANT TO 10 CFR 50.44 FOR CATAWBA AND MCGUIRE NUCLEAR STATIONS (TAC Nos. M63034, M63035, M63032, M63033)

Enclosed, please find the NRC ' staff's Safety Evaluation concerning the hydrogen control issue as set forth in Supplement No. 6 to the Catawba Safety Evaluation Report (NUREG-0954)(SSER-6). That SSER reported the closure of one of the three technical issues included in Condition No.14 of Facility Operating License NPF-35 for Unit I and provided an updated status on the two remaining issues addressed in Condition No. 14.

We have completed our review of your submittals that provide information on the implementation of the plan to resolve the issue that was outlined in your letter of April 25, 1986. We recognize that the Duke Power Company has expended considerable resources. responding to the requirements of this issue in 1986, 1988, 1989 and, most recently, in your letter of March 25, 1993. We feel that the commitment to resolving this concern, as -demonstrated in the scope and the thoroughness of your responses, is highly commendable.

On the basis, as set forth in the enclosed Safety Evaluation, we find that the remaining issues of compliance with 10 CFR 50.44, as set forth in SSER-6 and Condition 14 of license NPF-35, have been resolved for the Catawba Nuclear.

Station. As noted in the enclosed Safety Evaluation, these issues are also considered to be closed for the McGuire Nuclear Station.

Since el ,.

David B. Iatthews, Director Project Directorate II-3 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation

Enclosure:

Safety Evaluation cc w/ enclosure:

See next page 7 0-165

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l Mr. M. S. Tuckman. ,

Duke Power Company Catawba Nucle,ar Station lCC* '

Mr. R. C. Futrell Mr. Alan R. Herdt, Chief  :

' Regulatory Compliance Manager Project Branch #3 Duke Power Company U. S. Nuclear Regulatory Commission-4800 Concord Road- 101 Marietta Street, NW. Suite 2900 York, South Carolina 29745 Atlanta, Georgia 30323' Mr. A. V. Carr, Esquire North Carolina Electric Membership  !

Duke Power Company Corporation 422 South Church Street -

P. O. Box 27306 Charlotte, North Carolina 28242-0001 Raleigh, North Carolina 27611 J. MichTel McGarry, III, Esquire Senior Resident Inspector Winston and Strawn Route 2, Box 179 N 1400 L Street, NW York, South Carolina 29745 7 i

Washington, DC 20005 Regional Administrator, Region 11

• North Carolina MPA U. S. Nuclear Regulatory Commission.

Suite 600 101 Marietta Street, NW. Suite 2900 +

P. O. Box 29513 Atlanta, Georgia 30323 Raleigh, North Carolina 27626-0513 Mr'. Heyward G. Shealy, Chief .)

Mr. T. Richard Puryear Bureau of Radiological Health Nuclear Technical Services Manager South Carolina Department of .

Carolinas District Health and Environmental Control Westinghouse Electric Corporation 2600 Bull Street P. O. Box 32817 Columbia, South Carolina ' 27602 :l

-Charlotte, North Carolina 28232 Mr. G. A. Copp  ;

County Manager of York County Licensing - EC050 l

. York County Courthouse Duke Power Company York, South Carolina 29745 P. 0. Box 1006 Charlotte, North Carolina. 28201-1006 l Richard P. Wilson, Esquire  !

Assistant Attorney General Saluda River Electric South Carolina Attorney General's P. O. Box 929 Office- Laurens,~ South Carolina 29360-P.-0. Box 11549 Columbia, South Carolina 29211 Ms. Karen E. Long Assir. tant Attorney General l Piedmont Municipal- Power Agency North Carolina Department ~ of Justice  :

121-Village Drive P. O. Box 629 i Greer, South Carolina 29651 Raleigh, North Carlina 27602 l 1

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Mr'.'T. C. McMeekin Duke Power Company McGuire Nuclear Station cc:

Mr. A. V. Carr, Esquire Mr. Dayne H. Brown, Director 1 Duke Power Company . Department of Environmental, 422 South Church Street Health and Natural Resources .i Charlotte, North Carolina 28242-0001 Division of Radiation Protection P. O. Box 27687' County Manager of Mecklenberg County Raleigh, North Carolina 27611-7687 720 East Fourth Street Charlotte, North Carolina 28202 Mr. Alan R. Herdt, Chief Project Branch #3 Mr. R. O. Sharpe U. S. Nuclear Regulatory Commission Compliance 101 Marietta Street, NW. Suite 2900 Duke Power Company Atlanta, Georgia 30323 McGuire Nuclear Site 12700 Hagers Ferry Road Ms. Karen E. Long  !

Huntersville, NC 28078-8985 Assistant Attorney General North Carolina Department of j

J. Michael McGarry, III, Esquire ' Justice Winston and Strawn P. O. Box 629 1400 L Street, NW. Raleigh, North Carolina 27602 Washington, DC 20005 Mr. G. A. Copp Senior Resident Inspector Licensing - EC050 c/o U. S. Nuclear Regulatory Duke Power Company Commission P. O. Box 1006 12700 Hagers Ferry Road Charlotte, North Carolina 28201-1006 Huntersville, North Carolina 28078 Regional Administrator, Region II Mr. T. Richard Puryear U.S. Nuclear Regulatory Commission Nuclear Technical Services Manager ~101 Marietta Street, NW. Suite 2900 l Carolinas District Atlanta, Georgia 30323 Westinghouse Electric Corporation j P. O. Box 32817 Charlotte, North Carolina 28232 Dr. John M. Barry Mecklenberg County Department of Environmental Protection-  ;

700 N. Tryon-Street '

charlotte, North Carolina 28202 i I

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/k k UNITED STATES 77 .$* NUCLEAR REGULATORY COMMISSION

• WASWNGTON, D.C. 20555-0001 o

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION t DUKE POWER COMPANY. ET AL.

CATAWBA NUCLEAR STATION. UNITS 1 AND 2 MCGUIRE NUCLEAR STATION. UNITS 1 AND 2-DOCKET NOS. 50-413. 50-414. 50-369 AND 50-370 -

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1.0 INTRODUCTION

in NUREG-0954, " Safety Evaluation Report Related to the Operation of Catawba Nuclear Station, Units 1 and 2," Supplement No. 6, Para 6.2.5, (SSER-6) dated May,1986, the staff approved the licensee's April 25, 1986, plan for closure

• of the remaining issues related to combustible gas control. The three issues addressed in the plan are the subject of Catawba Nuclear Station Facility Operating License Condition No. 14. They are:

(1) Thermal response of the containment atmosphere and essential ,

equipment for a spectrum of accident sequences using revised heat transfer models, v (2) Effects of upper compartment burns on the operation and survival of air return fans and ice condenser doors, and (3) Operability of the glow plug in a spray environment typical of that expected in the upper compartment of the containment. l Catawba SSER-5 provided a detailed discussion of the i.ssues. By the time of preparation of SSER-6 the staff had completed its review of (3) above and was )

able to report that the issue of glow plug operability in a spray environment )

has been resolved. This safety evaluation ' addresses (1) 'and (2) above, the i two remaining hydrogen control issues. 1 Although this evaluation specifically refers to Catawba, the information and conclusions are applicable to McGuire.

2.0 DISCUSSION AND EVALUATION I

2.1 Thermal Response of the Containment Atmosphere and Essential Ecuipment for a Spectrum of Accicents Usino Revised Heat Transfer Models 1

Backaround (Recap from SSERs-5 & 6): At the time of issuance of the first Catawba unit operating license, the licensee had performed numerous analyses of the containment atmosphere pressure and temperature response during degraded core accidents with associated hydrogen release and combustion.

Calculations were performed, using the CLASIX code, to determine the

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-sensitivity to variations in assumed combustion parameters, assumptions regarding availability of safety systems, and variations in the hydrogen and '

steam release to the containment. Although many analyses were performed, for i purposes of determining environmental conditions for equipment survivability l requirements only the S2D (2-inch hot leg break LOCA with ECCS failure) sequence was considered.

The licensee stated that this sequence represented a reasonable upper bound scenario. The staff accepted this position on an i interim basis (Ref: McGuire SSER-7) with the condition that licensee' pursue this issue further. The staff had concerns with the use of the CLASIX code.  !

One problem was that it did not predict burning in the upper containment compartment, whereas, Sandia investigations had. The staff also determined that the licensee's CLASIX code contained errors in the heat transfer models which would cause underprediction of containment temperatures.

Discussion: In response to the NRC staff's concerns and in conformance to its  !

April 25, 1986, plan, the licensee conducted additional analyses of accident i sequences. A spectrum of accident sequences that envelop a wide range of l reactor vessel pressures was analyzed. Also, because of staff concerns l regarding ECCS recirculation failure, a recirculation failure sequence was added. ' The sequences include:

1

1. S D 6-inch hot leg LOCA with ECCS failure, 3

2. S2 D 2-inch hot LOCA with ECCS failure,

3. 52 H 2-inch hot leg LOCA with ECCS recirculation mode failure, and

4. TMLU Loss of main feedwater with failure of auxiliary feedwater and ECCS.

These sequences were examined with the Modular Accident Analysis Program (MAAP) Versions 2.0B and 3.0B to determine steam and hydrogen mass / energy release histories. Similar analyses were performed using the MARCH Code on D.C. Cook, Sequoyah, and McGuire and the results compared. Code input assumptions for the licensee's MAAP/HECTR analyses regarding (a) fan operation and timing, (b) ignition and propagation criteria, (c) combustion completeness, (d) flame speed, (e) heat transfer coefficients, (f) ice  !

condenser drain temperature, and (g) containment compartmentalization are best

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estimate letters. values and are identified in the April 25, 1986, and March 25, 1993, {

For redundant equipment, both trains are assumed operable. Hydrogen i burn parameters were based on a study of experiments carried out under the sponsorship of HRC, the ice condenser owners, and EPRI. These experiments include the large-scale tests at the Nevada Test Site as discussed in Catawba SSER-5.

i For each sequence, ECCS recovery was delayed until hydrogen production had peaked.

Hot leg breaks were chosen in order to minimize hydrogen holdup time.

None of the MAAP sequences resulted in clad oxidation greater than 25.2%.

Since the Hydrogen Rule (10 CFR 50.44) specifies a 75% zirconium / steam reaction capability, and the hydrogen production resulting from these

-sequences was considerably less, the licensee also analyzed the events using a non-mechanistic model to extend the hydrogen source term to 75% clad oxidation. The non-mechanistic model used to extrapolate hydrogen production to 75% clad oxidation was consistent with that used by the Hydrogen Control f

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-Owner's Group as described in the related staff Safety Evaluation Report (NUREG-1417). t i

The steam and hydrogen release histories from the MAAP'analy:es were used as'

. inputs to the HECTR code to determine the containment pressure and temperatu're 13wer plenum, lower containment and dead-ended volumes. responses, glo The HECTR Code, -i described in NUREG/CR-4507, is a lumped-parameter containment analysis code developed  !

to hydrogenfor calculating-the containment pressure and temperature responses combustion.  :

HECTR uses default hydrogen concentration limits for

-ignition and upward propagation which are lower than the values set in .CLASIX.

MAAP is an industry-developed code which has not been reviewed by the staff.  :

Therefore, the steam and hydrogen releas histories from MAAP were compared'to  !

steam hydrogen release histories predicted by the staff-approved MARCH code for other ice-condenser Sequoyah). facilities (i.e., McGuire, Donald C. Cook and t

t The MAAP/HECTR analyses resulted in global peak pressures and temperatures below the corresponding CLASIX results 6r all four sequences. However, the 4 MAAP/HECTR than CLASIX. analyses did result in some 'igher peak compartment temperatures ,

i' The following table presents comparisons of the peak temperature results.

PEAK TEMPERATURE COMPARISONS (deg.F.)

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.S.y SA Sg Upper Compartment 238.1 JEMLU. CLASIX Upper Plenum 270.3 239.9 284.2 c.

609.4 162- l 851.4 659.7 775.2 '

Lower Plenum 680.9 887.7 1517 Lower Comp;rtment 947.5 751.1 228 678.9 782.8 848.5 Dead-Ended Compartment 238.1 637.0 1138 301.3 328.6 263.7 i

238  !

The'significar: differences between the earlier CLASIX predici as and the .

MAAP/HECTR predicted by MAAP preuictions are the upper containment and lower plet a burns i higher ignition an/HECTR but not CLASIX. This is attributed primarily to the d propagation limits in CLASIX noted above.

burns are of little consequence since there is no equipment located there. Lower plenum.

However, the upper containment contains vital air return fans whose j survivability could be impacted by burns.  ;

By letter. dated February 3,1995, the staff informed the licensee that the accident scenarios selected for analysis encompassed an appropriate range of f events consistent with.10 CFR 50.44(c)(3)(vi)(B)(3). _

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9 4 l 2.2 Return Fans and Ice Condenser DoorsEffects of Onper Containment B!

Bekaround (Recao from SSERs-5 & 6):

-analyses indicated no burning in the upper compartment.As noted above, the licensee's tests, discussed in SSERS, thermal ignitors reliably ignited hydrogen-steam-Howeve!

air mixtures with hydrogen concentrations as low as approximately 5.5% volume percent. Also, Sandia MARCH /HECTR Ref:NUREG/CR-3912) analyses indicated higher steam fractions in the lower (compartment and numerous; uppe

~ burns.

indicated an increased flammability limit in .the upper plenunIn ai Based on these i findings for many the staff considered degraded hydrogen burns'in the upper comp.

core scenarios. artment likely Therefore, in addition to requiring ,

upgraded thermal response analyses, the staff required the licensee to address ,

the effects certain of upper containment safety-related e burns on the operation and survival of and ice condenser doors)quipment (i.e., air return and hydrogen skimmer fans These fan concerns relate to (1) differential pressure loads causing the fans to windmill thus generating sufficient current t

to trip on overload, and (2) ice condenser door reverse differential pressure loads.

[The fan temperature profiles for each sequence were determined independently using a different radiative heat transfer model.

were found to be. less limiting than the fan and cable profiles used in theThese profiles environmental qualification of electrical equipment per 10 CFR 50.49]. By letter dated March 25, 1993, the licensee submitted additional information  ;

. regarding the remaining issues of fan and door survivability. i Fan Survivability: .!

psid lasting 10 or more seconds is sufficient to trip theTo air return f address the concern of forward-direction fan windmilling, the licensee -

analyzed the fan and duct acting as a generator under the forward pressure differential.

2.7 psid. The 5 0 sequence resulted in a peak pressure differential of 3  :

psid. lhe SzD sequenced produced a peak differential pressure of 3.8 7

the TMLU produced a peak differential pressure of 4.25 psid.Th The latter  ;

exceeded the 4 psid value established as the minimum AP needed to trip the fan, but only for 5 seconds, half the time period necessary for the trip. >

analyses indicate that windmilling during the four accident sequence The conditionsthe overspeed would fans. not produce the fan motor currm t necesst.cy to trip or i

return fans. The hydrogen skimmer fans are less limiting than the air l

i Jce Condenser Door Ooerability:

Upper compartment burning may result in reverse differential loads on the intermediate deck and lower compartment inlet doors of the ice condenser.

' bypass ~ flow through ice condenser drains.To some extent the loads are relieved by- i

' to'the stress loads imposed by reverse pressure are beams up the middle o i door frames.

psid and 7 psid respectively (Ref:The differential pressures that the. doors can w April 25, 1986, letter).

resulted in reverse AP's less than 2.5 psid. The S,D sequence produced reverse AP's of less than 4 psid. The SzD and TMLU sequences AP's of. less than 3 psid. The S2 H sequence produced reverse The results of the MAAP/HECTR analyses indicate '!

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! that in no case do the calculated differential pressures approach the values 1

.which were calculated to result in damage to the door beams. '

3.0 CONCLUSION

L By this Safety Evaluation, the staff concludes that the two remaining

licensing issues identified-in SSER-6 and in Condition 14 of Facility l Operating License No. NPF-35 for Catawba Unit 1. consisting of (1) . thermal l

response of the containment atmosphere and essential equipment'for a. spectrum -

of accident sequences using revised heat transfer mod < tis, and (2) effects of upper compartment burns on the operation and survival of air return fans and .

ice condenser doors, have been resolved to the satisfaction of the staff. In i

consideration of the similarity in design of the Catawba and McGuire plants  ;

and the applicability of the supporting documentation and analyses' submitted i by the licensee to both the Catawba and McGuire Nuclear Stations, the NRC '

staff concludes that the remaining provisions of 10CFR 50.44(c)(3) have been acceptably responded to for both stations.  !

Principal Contributor: W. Long  !

Date: May 26, 1993 i

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