ML20203L823

Forwards Request for Addl Info to Verify Capability of CEFLASH-4AS Computer Program to Calculate Core Level Depression Prior to Clearing Reactor Coolant Loop Seals Based on Semiscale Test S-UT-8 Data,Per 860812 Meeting

ML20203L823
Person / Time
Issue date:	08/27/1986
From:	Crutchfield D Office of Nuclear Reactor Regulation
To:	Holman J C-E OPERATING PLANTS OWNERS GROUP, LOUISIANA POWER & LIGHT CO.
References
TASK-2.K.3.30, TASK-TM NUDOCS 8608290214
Download: ML20203L823 (5)

Text

a August 27, 1986 Mr. Jerry Holman, Chairman CE Owners Group Analysis Committee Mail Unit 17 Louisiana Power & Light 317 Baronne Street New Orleans, Louisiana 70160 Cear Mr. Holman:

SUBJECT:

VERIFICATION OF ANALYSIS FOR SMALL BREAK LOCA's; TMI ACTION ITEM II.K.3.30 FOR COMBUSTION ENGINEERING PLANTS; POST TEST ANALYSIS OF SEMISCALE TEST S-UT-8 On August 12, 1986, representatives of the Combustion Engineering Owners Grot.p (CE0G) met with the staff to discuss the capability of the CEFLASH-4AS computer program to calculate the core level depression prior to the clearing of the reactor coolant loop seals as observed in the data from Semiscale Test S-UT-8.

At that meeting, the CE0G presented new information which supports its position that CEFLASH-4AS includes the features necessary to predict or conservatively bound the core level depression observed in the S-UT-8 data.

In order for the staff to evaluate this information and, hence, to complete its review of this subject, it needs the additional information identified in Enclosure I.

It is requested that this information be provided within 30 days of the date of this letter.

Original signed tp Dennis M. Crutthfislo Dennis M. Crutchfield, Assistant Director Division of PWR Licensing-B

Enclosure:

As stated cc:

W. Minners DISTRIBUTION R. Bosnak Central Filed M B. Sheron RSB File PDR Elantz NLauben CThomas DCrutchfield

• See previous concurrence sheet S

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August 27, 1986 Mr. Jerry Holman, Chairman CE Owners Group Analysis Committee Mail Unit 17 Louisiana Power & Light 317 Baronne Street New Orleans, Louisiana 70160

SUBJECT:

VERIFICATION OF ANALYSIS FOR SMALL BREAK LOCA's; TMI ACTION ITEM II.K.3.30 FOR COMBUSTION ENGINEERING PLANTS; POST TEST ANALYSIS OF SEMISCALE TEST S-UT-8 On August 12, 1986, representatives of the Combustion Engineering Owners Group (CE0G) met with the staff to discuss the capability of the CEFLASH-4AS computer program to calculate the core level depression prior to the clearing of the reactor coolant loop seals as observed in the data from Semiscale Test S-UT-8.

At that meeting, the CEOG presented new information which supports its position that CEFLASH-4AS includes the features necessary to predict or conservatively bound the core level depression observed in the S-UT-8 data.

In order for the staff to evaluate this information and, hence, to complete its review of this subject, it needs thc additional information identified in Enclosure 1.

It is requested that this information be provided within 30 days of the date of this letter.

Denn s M. Crutch ie

,A ista t Director l

Division of PWR Licensi g-B

Enclosure:

1 As stated cc:

W. Minners l

R. Bosnak l

B. Sheron l

J ENCLOSURE I REQUEST FOR ADDITIONAL INFORMATION FOR VERIFICATION OF ANALYSIS METHODS FOR SMALL BREAK LOCA's: TMI ACTION ITEM II.K.3.30 FOR COMBUSTI0h ENGINEERING PLANTS: POST TEST ANALYSIS OF SEMISCALE TEST"S-UT-08 1.

Please provide the basis for each of the " QUALITATIVE EFFECT IN TEST S-UT-8" designations of " BIG", " MEDIUM", and "SMALL" in Enclosure A.

Where applicable give a specific reference (page no. and paragraph to a previous submittal for each item).

2.

In the August 12th meeting, the CE0G stated that the " foot" of the core level depression between approximately 200 and 240 seconds (see S-UT-8 data curve in Enclosure B) is primarily due to the core rewet steam production in S-UT-8 and that an earlier calculation demonstrated this effect.

Please discuss the earlier calculation or provide some other basis for this conclusion.

3.

To demonstrate the adequacy of the EM model, the CE0G used a BE/EM

~

model for S-UT-8.

Please show why all of the portions of the EM model that were not in the BE/EM model have little or no effect on the core uncovery spike.

4.

Please provide the slides used in the August 12, 1986 presentation.

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ENCLOSURE A*

FACTORS AFFECTING CORE UNC0VERY SPIKE IN TEST S-UT-8 e

FOR SPIKE TO OCCUR, THE-UPPER PLENUM PRESSURE MUST.BE GREATER THAN THE DOWNCOMER PRESSURE DURING PUMP SUCTION LIQUID SEAL EXISTENCE.

e THE FOLLOWING FACTORS CAUSE QUALITATIVE EFFECT THE UPPER PLENUM PRESSURE T0 IN TEST S-UT-8 BE HIGHER (EXCEPT #5):

MODELED IN BE/EM 1.

HIGHER INVENTORY LEVEL IN SG UPFLOW SIDE BIG YES THAN DOWNFLOW SIDE (LIQUID HOLDUP) BECAUSE 4

A.

UPPER HEAD DRAINING INTO UPPER PLENUM BIG YES(EM)

SUPPLIES INVENTORY WHICH IS CARRIED INTO SG UPFLOW SIDE B.

SG DOWNFLOW SIDE LOOSES INVENTORY MEDIUM YES(EM)

FASTER THAN UPFLOW SIDE C.

CCFL IN SG SLOWS UP DRAINING 0F SMALL N0(EM)

UPFLOW SIDE D.

MORE CONDENSATE IS GENERATED IN UPFLOW SMALL N0(EM)

SIDE OF SG 2.

FRICTIONAL LOSSES IN " PANT LEG" DURING MEDIUM YES(BE)

COUNTERCURRENT FLOW ADDS TO THE LOOP PRESSURE LOSSES 3.

WALL HEAT IN CORE REGION MEDIUM YES(EM) 4.

CORE REWET STEAM PRODUCTION MEDIUM N0(EM) 5.

BYPASS LINE PROVIDES PATH FOR STEAM FROM SMALL N0(EM)

UPPER HEAD TO DOWNCOMER

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6.

EQUILIBRIUM FLUID STATE IN THE COLD LEGS SMALL YES(EM)

AND DOWNCOMER DURING HPSI FLOW 12, 1986 This is a copy of vu-graph provided by the CE0G in a meeting on August

ENCLOSURE B*

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• This figure was taken from p. 7-14 CEN-203-P, Revision 1-P, Supplement 3, and R. We'lls, CEOG has indicated that the figure can be released to the general public.

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