ML20236K523

Summary of 980618 Meeting W/Ceog in Rockville,Md Re Moisture Carryover Credit in Main Steam Line Break Accident Analysis. Attendees List & Viewgraphs Encl

ML20236K523
Person / Time
Issue date:	07/06/1998
From:	Stewart Magruder NRC (Affiliation Not Assigned)
To:	Essig T NRC (Affiliation Not Assigned)
References
PROJECT-692 NUDOCS 9807090357
Download: ML20236K523 (17)

Text

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WASHINGTON, D.C. 20066 0001

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July 6, 1998 i

MEMORANDUM TO: Thomas H. Essig, Acting Chief l

Generic issues and Environmental Projects Branch l

Division of Reactor Program Menagement Office Of Nuclear Reactor Regulation FROM:

Stewart L. Magruder, Project Manager afLd 1.

Generic issues and Environmental Projects Branch Division of Reactor Program Maragement Office of Nuclear Reactor Regulation

SUMMARY

OF JUNE 18,1998, MEETING WITH THE COMBUSTION ENGINEERING OWNERS GROUP (CEOG) l On June 18,1998, a public meeting was held at the U.S. Nuclear Regulatory Commission (NRC) offices in Rockville, Maryland, between representatives of the NRC and the Analysis Subcommittee of the CEOG. Attachment 1 provides a list of attendees.

The purpose of the meeting was to discuss moisture carryover credit in main steam line break (MSLB) accident analyses. The CEOG requested the meeting to (1) apprise the staff of CEOG activities and tentative plans in this area, (2) seek staff input on the technical approach and identify any current concerns, and (3) discuss the appropriate timing of the submittal of potential topical reports. The CEOG presentation material from the meeting is included as Attachment 2.

A representative of ABB-CE first gave a brief overview of what had been done in the first phase of their task. This included a discussion of the analysis tools used by CEOG plants, a description of the test facility used to develop data, and the results of the tests. The staff raised some questions about the scaling analysis done with the experimental data and the moisture droplet size (i.e. Infinite heat transfer between water and vapor) used in the analysis.

Next, another ABB-CE representative discussed the development of the new moisture j

carryover algorithm and how it may be applied to the analysis tools used by CEOG plants. The

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results of the algorithm indicate that if credit can be given for moisture carryover in a MSLB, the

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calculated energy released into containment is reouced and the total calculated reactivity increase is reduced.

The group then discussed the fact that this application would effectively tie the steam generator model with the containment model and that a conservative approach should be taken. The fact that moisture carryover reduces containment temperature and, therefore, changes the equipment environmental qualification envelope was also discussed. The staff noted that an i

overall plant analysis would be helpful to study the long term effect on the primary system.

' Additional suggestions from the staff included taking a close look at the statistical analysis done 9807090357 980706 I

PDR TOPRP ENVC-E C

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T. Essig July 6, 1998 In the experimental data reduction, justifying that the correlations developed from steady-state experimental data bound the dynamic event, and submitting any topical reports on a licensee's docket.

Project No. 692 l

l Attachments: As stated cc: See nce page l

i

T. Essig July 6, 1998 in the experimental data reduction, justit ving that the correlations developed from steady-state experimental data bound the dynamic es ent, and submitting any topical reports on a licensee's docket.

Project No. 692 Attachments: As stated i

cc: See next page DISTRIBUIlON: See attached page Document Name:g:\\simi\\rnsum0618.98

• See Previous Concurrences

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SC:P[Bj OFFICE PM:PGEB SRXB SCSB Micz NAME SMagruder:sw*

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'JY98 DATE 6/29/98 7/6/98 7/6/98 OFFICIAL OFFICE COPY I

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l' Distribution: Mtg. Summary w/CEOG Dated _ July 6,1998 Hard. Copy Central Files PUBUCi PGEB R/F OGC ACRS SMagruder EMail SCollins/FMiraglia BSheron BBoger JRoe DMatthews GHolahan EWeiss FOrr JKudrick KCampe CLiang JDonoghue JKelly, RES FAkstulewicz SMagruder l

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NRC/CEOG MOISTURE CARRYOVER MEETING ATTENDEES June 18,1998 l

I NAME ORGANIZATION Mark Finley BGE Mark Janke ABB-CE l

Don Streinz ABB-CE l

Paul Hijeck ABB-CE l

Eric Weiss NRC/NRR l

l Frank Orr NRC/NRR Jack Kudrick NRC/NRR Kaz Campe NRC/NRR Chu-yu Liang NRC/NRR l

Joe Donoghue NRC/NRR Joe Kelly NRC/RES Stu Magruder NRC/NRR l

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I CE Owners Group Analysis Subcommittee Moisture Carryover Credit in MSLB Meeting with NRR Staff June 18,1998 CEOG Analysts Subcomminee NRR Staff Meeting June 18.1998 1

i Today's Discussion j

1 e Program overview i

e CEOG understanding of current regulatory position e Moisture carryover data / algorithm i

e MSLB / MCO transient analysis e Future plans CEOG Analysis Subcommmee NRR Staff Meeting June 18,1998 l

l 1

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l Program Background l

l e Early CE studies of separation system indicated i

substantial moisture carryover (MCO) under high steam flow scenarios.

o MSLB transient analyses indicate reactivity and containment mass energy benefits.

o Current safety analyses include partial or no MCO l

consideration in MSLB.

l e CEOG approved a phase 1 feasibility study of MCO in MSLB. Phase 2 is pending discussion of preliminary results.

CEOG Anaysis Subcommittee NRR StaN Meetng June 18,1998 CEOG MCO in MSLB Phase 1 Tasks e Review licensing status e Review analysis tools e Quantify MCO impact I

e Meet and discuss with NRR Staff CE00 Anaysis Subcommittee NRR Sta# Meetng June 18,1998 l

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i Phase 1 Task Results Licensing Review l

e SRP 6.2.1.4 Mass and Energy Release Analysis...

n Section 2: Liquid Entrainment-Supp~ ort by experimental data; Consider steam separators; Analyze spectrum of break sizes Section 4: CSG compare experimental data in submittal to other experimental data e PDR references Westinghouse plant use of MCO ln MSLB a Unclearif MCO creditis approved o CENTS model with MCO - Acceptable SER for KAERI for l

Westinghouse Plants (Benchmarked to RELAP) l t

CEOG Analysis Subcommmee NRR StaN Meetng June 18,1998 i

l Phase 1 Analysis Tools Overview e All CE Owners use SGN lli for MSLB Containment M/E Analysis Sing'e node SG l

l n Wilson Bubble Rise Model capability l

n MCO correction factor is scaleable e Some CE Owners use CENTS for MSLB Reactivity Analysis l

n Three node SG l

n Employs best-estimate simulation similar to RELAP and i

other best-estimate models n MCO is generally implicit in calculation when tumed "On" CEOG Analysis subcommmee NRR StaN Meetng June 18.1898 l

1

l 1

l Phase 1 Task Results 1

Overview 1

e Analysis-i a Compared:

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- CENTS w/o MCO

- CENTS with MCO *On"

- CENTS with MCO new algorithm

- SGN lit w/ no MCO

- SGN lil w/ MCO e Results:

a Substantial MCO overwide range of break sizes a MCO credit indicates substantial benefit in reactivity (return j

to power) and containment mass and energy release i

cEOG Analysis subcommittee NRR Stan Meetng June 18.1996 I

. Phase 2 Preliminary Program e CEOG to Consider Phase 2 pending results of Phase i

1 and meeting with NRR Staff e Program elements n Develop tools for MSLB with MCO analyses I

n Determine limiting MSLB size Quantify MCO benefit

- Reactivity

-Containment mass and energy load Develop topical report CEoG Analysis subcomnuttee NRR StaN Moebng June 18,1998 l

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-_--___--s--_--___------a.._-.___

I PHASE 1 Algorithm Development Task e Purpose Analyze laboratory MCO data for CE SG separation system emphasizing MSLB conditions e Background Laboratory and operating plant data have shown that l

high steam and water flow rates and high water levels significantly increase MCO e Coal n Develop empirically based algorithm accounting for MCO during transient conditions when modeled in current MSLB analysis codes CEOG Analysis Subcommittee NRR Sta# Meebng June 18,1998 Typical CE Steam Generator

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Ein CEoG Analysis Subcommittee NRR Stan Meeung June 18,1998

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l Basis for MCO Algorithm l

e team nozzle moisture discharge from two sources a MCO from separator a Moisture which bypasses separator resulting from downcomer flow reversal during MSLB e Empirical algorithms model n moisture discharged from the separator j

> moisture discharged from the drier e Fluid bypassing the separators is modeled by MSLB transient code e Complete model sums the two sources entering the drier CEOG Analysis Subcomrmttee NRR StaN Meeting June 18,1998 MCO Test Facility Mockup Description e Full scale first and second stage separators installed in large pressure vessel e Range of steam and water mixtures (qualities) controlled by mixing tee upstream of separation system Steam and water flow measured before mixing tee j

l e Steam flow out of system measured in discharge line e Separated liquid measured shroud around first stage separator, final separator drain line and in moisture sump i

CEoG Analysis subcommittee NRR Stan Meehng June 18,1996 I

l L_________.__...._._.__._________._.._

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Range of Test Data l

l Test Data NSSS MCR Steam Flow (Ib/s) 8.3 25.8

[ proprietary -

Water Flow (Ib/s) 24.2 89.7 column intentionally Water Level (ft) 0.1 - 2.7 blank Pressure (psie) 640 -1210 j

Separator Area (ft2) 1.805 Drier Area (ft')

0.813

]

CEOG Analysis Subcommmee NRR Stan Meeting June 18,1998 Empirical Algorithm Description e Algorithms are best-fit regression equations I

e Separate MCO algorithms developed for separators

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and driers e " Carry-in" algorithm (MCO from separator) is function of separator inlet steam flow and water flow and water level on the the separator shell e " Carry-over" algorithm (MCO from drier) is a function of " carry-in" Note: Bypass flow must be added to "cany-in" when determining " carry-over" CEOG Analysis Subcornmmee NRR Sta# Meenn0 June 18,1998 l

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" Carry-in" Algorithm Cl a exp(Co+C1*In(WL)+C2*In(Ww)+C3*In(Ws/(p^0.5)))+/-Sy where:

Cl = Moisture carry-in (Ib/s)

WL = Separator water level (ft above separator deck)

Ww = Water flow rate (Ib/s)

Ws = Steam flow rate (ib/s) p = Steam density (Ib/ft))

in = Naturallogarithm Sy = Standard deviation of data fit (Ib/s)

Cx = Regres,sion coeff!J ents CEOG Analysis Sh..

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NRR Stan Webng June 18,1998 CEOG MSLB / MCO

" Carry-over" Algorithm CO = Bo+B1*Cl^B3+B2*Cl +/-Sy where:

CO = Moisture carry-over (Ib/s)

Cl = Moisture carry-in to final separator (Ib/s)

Bx = Regression coefficient Sy = Standard deviation of fit (Ib/s)

CEOG Anaysis Sutccrrmttee NRR StaPtl@ June 16,1996

Phase 1 Analysis Task Method e Run cases for large, medium, small MSLB sizes e Use SGN lli and CENTS codes e CENTS

' with no MCO with current MCO approach enabled a with new MCO algorithm e S G N lli with no MCO with current MCO approach enabled CEOG Analysis Subcommmee NRR Staff Meetmg June 18,1998 Analysis Tools Review e S G N lli Single node SG

> Wilson Bubble Rise Model-scaleable flow velocity coefficient (Zeta)

- Zeta range = 1.0 - 2.5

-Z= 2.5 for " normal" MSLB = no MCO

- Z=1.0 - 1.4 for " normal" MSLB = MCO e CENTS

> Best-Estimate model with 3 node SG

> Enable / Disable control for MCO CEOG Analysis Subcommmee NRR Steft b.se6ng June 18,1998 m_

Cases Run CODE BREAK SIZE MCO Case 2

SGN 111 6.35 ft No (Z=2.5) 6.35 ft Yes (Z=1.0)

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2 CENTS 6.35 ft' No 2

6.35 ft Yes (current algo) 6.35 ft' Yes j

(proposed algo) 3.0 ft:

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(proposed algo) 2.1 ft' Yes (proposed algo)

CEOG Analysis Subcommittee NRR Staff Meeting June 18.1998 l

. Analysis Results j

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CASE AVERAGEM/C BLOWDOWN POST TRIP (fraction)

ENERGY (BTUs) (d rho)

SGN3 (6.35, ZETA =2.5) 0.000 246E+06 N/R SGN3 (6.35, ZETA =1.0) 0.560 163E+06 N/R CENTS (6.35, no M/C)

.000 264E+06

.0219 CENTS (6.35, current sigo) 0.217 219E+06 0305 CENTO (6.35, new s190) 0.491 191E+06

.0444

?ENTS (3.0, new a1 0) -

0.312 242E+06

.0321 9

CENTS (2.1, new alco) 0.226 269E+06

.0269 CEOG Analysis Subcommittee NRR S*** Meetng June 18.1998

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SUMMARY

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e Phase 1 of CEOG task is complete e Algorithm and analyses were supported by j

l experimental data and RELAP (via KAERI CENTS) j e MCO results compare favorably to approved codes e Substantial MCO is predicted - represents margin in 4

containment and reactor core reactivity response for

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small to large MSLB e CEOG further consideration of Phase 2 is pending l

feedback from this meeting e Further NRR Staffinput is welcome l

CEOG Analysis Subcommittee NRR Sta# Meeting June 18.1998 j

Discussion l

e is the Staff aware of any MCO credit"show

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stoppers"?

i e Any Staff concerns not previously raised?

e Timing of submittal of a topical (if project phase 2 l_

authorized by CEOG) to be determined.

l' e Otherdiscussion?

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e Thank you for meeting with us today l

CEOG Analysis Subcommmee NRR Sts# Meeting June 18,1998 i

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CE OWNERS GROUP Project No. 692 cc:

Mr. Gordon C. Bischoff CEOG Project Manager ABB Combustion Engineering M.S. 9615-1932 2000 Day Hill Road l

Windsor, CT 06095 Mr. David Pilmer, Chairman CE Owners Group San Onofre Nuclear Generating Station I

14300 Mesa Road l

San Clemente, CA 92672 Mr. Ian C. Rickard, Director Nuclear Ucensing ABB-Combustion Engineering, Inc.

Post Office Box 500 2000 Day Hill Road Windsor, CT 06095 Mr. Charles B. Brinkman, Manager Wachington Operations ABB-Combustion Engineering, Inc.

12300 Twinbrook Parkway, Su;te 330 Rockville, MD 20852 i

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