ML20150E030
| ML20150E030 | |
| Person / Time | |
|---|---|
| Issue date: | 11/28/1978 |
| From: | Phillips L Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7812110080 | |
| Download: ML20150E030 (14) | |
Text
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UNITED STATES
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NUCLEAR r1EGULATORY COMMISSION s,
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WASHINGTON, D. C. 20555 g
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,,r NOV 2 81978 MEMORANDUM FOR:
U. S. Standard Problem Participants l
FROM:
L. E. Phillips, Section Leader, Analysis Branch, DSS
SUBJECT:
STANDARD PROBLEM MEETING MINUTES The meeting minutes for the Standard Problem Meeting held at NRC Headquarters in Bethesda, Maryland on September 6 and 7,1978 are enclosed.
Sincerely, L. E. Phillips, n Leader Analysis Branch Division of Systems Safety Office of Nuclear Reactor Regulation
Enclosure:
As stated cc: See attached distribution list 781211 DO$'O l
DISTRIBUTION - Meeting Summary S. Hanauer R. Mattson ACRS (10)
R. Tedesco L. S. Tong (1130 SS)
Z. Rosztoczy Central / Docket File NRR Rdg. File AB Rdg. File I_&E (3) (E/W Towers)
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U. S. Standard Problem Participants Meeting Attendees
T ENCLOSURE MEETING MINUTES STANDARD PROBLEM MEETING SEPTEMBER 6 AND 7, 1978 A meeting was held September 6 and 7,1978 at NRC Headquarters in Bethesda, Maryland on the U.S. Standard Problem Program. Attending were representatives oftheNRC,INEL,EPRI/EI,B&W,CE,W,GRS(Germany),GE-KAPL,and Westinghouse-Bettis. A list of attendees is enclosed.
Summary The major areas of discussion were the presentation of pre-test predictions for U.S. Standard Problem 8 (Semiscale Test S06-3), a presentation of a proposal for Standard Problem 9 (FLECHT-SEASET), a consideration of proposals for future standard problems and a discussion of previous comments on the Standard Problem Program Plan.
Semiscale Test S06-3 was the first integral blowdown, refill and reflood test analyzed under the Standard Problem Program.
INEL presented comparison plots of six selectea variables for all participants. The general m,
conclusions were that the fluid flow models resulted in predictions in agreement with the experimental data during the blowdown portion of the 4
transient. During the blowdown, W^stinghouse and EI/EPRI overpredicted the high power rod temperatures at elevations 22 to 39 inches, and CE under-predicted the high power rod temperatures in the same region. The CE and Westinghouse calculation of high power rod temperature at the 27 and 39 inch elevations overpredicted the data during the reflood portion of the transient.
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. The FLECHT-SEASET proposal by Westinghouse was accepted as Standard Problem 9.
There will be a delay is, the schedule for prediction reports to accommodate a small break experiment which will be analyzed by the vendor organizations outside the scope of the Standard Problem Program.
The participants were requested to review the selected parameters in the FLECHT-SEASET experiment and to identify what initial boundary conditions should be specified. A request for this information will be distributed through the NRC.
In the discussion of possible future standard problems, Westinghouse discussed a possible standard problem performed on the MOD-3 Semiscale facility modified for upper head injection.
Some participants indicated no intent to analyze this test as a standard problem. No action will be taken at.this time.
A small break experiment will be perfonned on the M00-3 facility under NRC sponsorship. This test will be analyzed by vendor organizations as part of a small break code verification. The small break test was voted down as part of the Standard Problem Program.
With regard to other future standard problems, consideration was given to formation of a Standard Problem subcommittee to compile a list of reflood and general LOCA experiments, both U.S. and International. Dr. Winkler of GRS presented a summary of the German Standard Problem program.
The Standard Problem Program Plan received a number of comments at the previous Standard Problem meeting (Palo Alto, October,1977). These
. comments were addressed and the resolution noted. The next action will be issuance of the Plan under cover letter from NRC.
The long range schedule projects the LOFT nuclear test L2-3 as Standard Problem 10 with September,1979 as the earliest projected date for running the test. The attached planning schedule reflects this date. Additional standard problems will be proposed as comments on the list of U.S. and International tests are received.
Details The two-day meeting was chaired by Larry Phillips of NRC. As agreed to at the last meeting, INEL (E. Gruen) presented comparison plots of hot channel and average channel rod temperatures, upper plenum pressure, break flows near the vessel and pump side and mass flow rate at the core inlet. The hydraulic models resulted in predictions of mass flows con-sidered to be reasonably close to data error bands. CE overpredicted core flow between 5-10 seconds. The upper plenum pressure was predicted well except for the INEL calculation which showed a rapid depressurization.
The clad temperature predictions showed a wide spread from the data. The high predictions by INEL were attributed to difficulty with the heat transfer routine in RELAP/M006.
Combustion Engineering (J. F. Kapinos) presented comparisons of depressurization rate, heater rod temperature transient and safety injection tank delivery.
The CE calculation was carried out to 100 seconds with no Appendix K code options in effect. The hot rod temperature at the 27-inch elevation appeared
1 to compare well with thermocouples D4-29 and E4-28; however, the calculated temperature showed an early DNB and an early rewetting. There was a discrepancy in accumulator flow which was typical of otner participants results. Mike Langerman (INEL) commented that this is not considered unusual in Semiscale data.
EPRI/EI (G. Sawtelle) ran the calculation to end-of-bypass only (the reflood model in RETRAN is not developed to the point that non-equilibrium conditions during ECCS injection can be accommodated). The EI calculation used modified initial conditions for lower plenum pressure, pump rated head, steam generator liquid level and steam line flow to reflect RETRAN state-of-the-art predictions. El recommended that the initial liquid mass in the steam generator secondary side be specified in future standard problems. EI identified an incorrect specification in the initial conditions for HPIS flow.
In the test data the HPIS flow did not reach the specified value of 1.3 gpm until 25 sec. The 0.3 gpm flow prior to 25 sec. is attributed to instrument fluctuation.
EI used the specified accumulator flow rate as a constant value input. This eliminated the discrepancy in peak flow predicted by other participants but introduced an initial difference as a result of the delay in the experimental data.
The El calculation of clad temperature showed an early DNB compared to the data for the low and high power rods. Several thermocouples measurements were plotted to illustrate the spread in clad temperature at different core locations.
The INEL (E. Gruen) calculation was completed to end-of-refill (about E0 seconds) and used the best-estimate version of RELAP M006. The INEL
- - _ _ _ _ _ _ _ _ _ calculated accumulator flow rate was high compared to the experimental data.
The blowdown portion of the INEL calculation showed a rapid depressurization and an early end-of-refill (47.2 sec.) compared to the test data (75 sec.).
The resulting clad temperatures were overpredicted for both the average and hot channels.
INEL used a one-node circumferential downcomer model; studies have shown that Semiscale (as opposed to LOFT) calculations are not sensitive to downcomer noding. For the post-analysis, INEL proposed to incorporate a quality-dependent vertical slip model in the core, a sensitivity study on the HEM break flow multiplier and continued improvement in the heat transfer models in RELAP/M006. CE made the comment that the bypass model might be causing some difficulty in the INEL calculation.
Westinghouse (N. Liparulo) made three modifications to the Appendix K version of the SATAN code for the blowdown calculation of S06-3, and best-estimate values were used for all input parameters. The modifications were incorporation of a slab heat transfer calculation, the addition of the physical properties of the heater rods and post-DNB heat transfer based or the model developed for UHI plantt. Westinghouse was the third participant to overpredict the accumulator flow rate.
The Westinghouse blowdown prediction in general gave reasonable homparisons with data for the hydraulic parameters.
It was recommended that break flow be given as an initial condition for future standard problems. The
_ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ hot channel clad temperatures were not computed in the Westinghouse analysis. The computed temperatures for the average rod at the specified elevations were overpredicted. As was true of other participants, the Westinghouse calculation underpredicted the time of DNB.
In summary, the fluid flow models used by the four participants performing a pretest prediction of Semiscale Test S06-3 appeared to result in reasonable comparisons with the data.
In general, the heat transfer models need more investigation in such areas as underpredicted time of DNB and early quench time.
The first day's session was adjourned after the presentations of 506-3 pretest predictions.
The second day began with a consideration of the Westinghouse proposal for Standard Problem 9 (W/NRC/EPRI FLECHT-SEASET reflood experiment) presented by Larry Hochreiter. The proposal was modified relative to a previously distributed document to reflect the selection of two tests out of the FLECHT test matrix rather than the two tests specifically selected for the standard problem. The only two conditions changed are the pressure at the top of the test burdle and the injection water temperature. The tests will be conducted on an unblocked 17 x 17 test bundle. The program schedule calls for issuance of the task plan in December,1978, and issuance of the data report in October,1979. The task plan will be distributed to interested parties and will contain a detailed description for modeling the test bundle or 1
system. The NRC will request participants to review the test parameters and make comments on what initial conditions and comparisons are of interest.
. 'iated with this will be a specification by participants as to their to model the system as a whole or the test bundle only. The
- 1...e. t planning schedule enclosed establishes September,1979 for submittal of calculations. The schedule was postponed from the previously specified data to allow for a pre-test prediction of a small break experiment to be analyzed by the vendor organization outside the scope of the Standard Problem Program.
In a discussion of future standard problems, Westinghouse discussed modifications to the Semiscale facility for upper head injection and external downcomers and suggested a pre-test prediction as a standard problem.
CE and B&W indicated no intent to analyze this test as a standard problem. W and NRC are already committed to a pretest prediction.
No action will be taken at this time.
A small break experiment is scheduled to be performed in December on the MOD-3 Semiscale facility under NRC sponsorship. This test is scheduled to be analyzed by vendor organizations as part of a small break code verification. The small break test was voted down as part of the Standard Problem Program.
With regard to other future standard problems the possibility of formation of a Standard Problem subcommittee was considered for the purpose of compiling a list of U.S. and International reflood and LOCA experiments.
The experiments would be evaluated as potential standard problems.
Dr. Winkler (GRS) summarized ti. German tests being planned in the near future. The NRC will coordinate the effort of compiling the list of future experiments and distribution of the list for comments, additions, and evaluation 1
. of relative importance of the experiments.
Comments from participants on the Standard Problem Program Plan received at the previous Standard Problem meeting (Palo Alto, October,1977) were reviewed and the NRC resolution was identified. These comments were itemized in the meeting minutes of the October,1977 Standard Problem meeting.
The specific resolution of each item is outlined below.
1.
(a) eliminate reference to acceptance bands in favor of questions from NRC - YES Comments: NRC - only two participants in LOFT L1-4 have responded to questions as of September 1.
(b) tone down emphasis on mandatory participation in post-analysis - NO Comments: W - disagrees with SP approach to verification CE - depth of post-test analysis should be decided on by individual participants.
2.
de-emphasize licensing aspects - NO Comments: CE - leave SP program as best-estimate.
3.
Sof ten wording to remove licensing club in favor of research role - N0 1
l Comments: CE - long range plan considered good idea - leave as best-estima te approach NRC - consider changes to Appendix K within limits of data.
EPRI - leave best-estimate approach in.
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4 Change wording at end of Section IIC to clarify that evaluation model calculations are performed only for selected cases - YES Comments: NRC - will look at overall document for consistency.
5.
Clarify benefits of program for participants' management - YES Comments: NRC - will address attributes of program and how used by NRC in transmittal letter 4
6.
Provide more equal treatment for BWRs and emphasize separate effects tests.
YE Comments. NRC - will consider alternate tests as standard problems.
^
7.
Clarify NRC concurrence in selection of standard problems (p.11)- YES Comments: NRC - will review document for consistent indication that NRC concurrence is required.
8.
Review of program plan document by NRC legal staff
- YES Comments: NRC - Office of Legal Director will have opportunity to canment 9.
Specification of computer type and CPU time
- NO Comments: NRC - will take out of document.
The NRC will make modifications to the SPP plan document and make distribution to participants.
A new Standard Problem planning schedule is attached to these minutes.
?
Sep tember,1978 STANDARD PROBLEM PLANNING SCHEDULE Event 8
9 l
10
{
11 Proposal
- 9-77(1) 2-78(1)
Accept Proposal 10-77(1) 9-7-78(1) 6 80 Specification Report
- 11-77(1) 3-31-79 10-79 Distribute Actual Initial Conditions 11-77(1) 3-31-79 10-79 Submit Calculations 4-30-78(1) 9-79 1-15-80 Distribute Experimental Data 6-15-78(1) 10-79 4-1-80 Preliminary Evaluation Meeting' 9-6-78(1) 12-01-79 6-15-80 Preliminary Report With Experimental Error Bands 11-
-78 4-1-80 10-80 Issue NRC Questions 11-30-78 4-15-80 11- -80 Submit Post-Test Analysis Results, Answer Questions, and Make Comments on Preli-minary Report.
3-01-79 7-01-80 1-15-81 Distribute Final Report
- 6-15-79 10-01-80 5-81
- Distributed From NRC (1) Completed
- Standard Problem Meeting with Presentation by Participants of Comparison Plots (Prediction and Experimental Data).
- LOFT L2-3 chosen in conjunction with SP 8 (semiscale counterpart Test S-06-03)
August 6, 1978 Standard Problem Meeting Attendance List Participant Organization L. Phillips US NRC M. McCoy US NRC W. Lanning NRC-RES George Sawtelle Energy Inc.
Nobuyuki Fujita Energy Inc.
Lance Agee EPRI John Kapinos CE Everett Gruen INEL/EG&G, Idaho W.T. Lanier GE-KAPL F.W. Lincoln Westinghouse - Bettis R.C. Jones B&W H.A. Bailey B&W J.J. Cudlin B&W W.J. Johnson Westinghouse V.J. Esposito Westinghouse W. Winkler GRS N.J. Liparulo Westinghouse M.A. Langerman INEL/EG&G
August 7, 1978 Standard Problem Meeting Attendance List Participant Organization Larry Phillips NRC Mike McCoy NRC George Sawtelle Energy Inc.
Everett Gruen INEL/EG&G Idaho C.F. Obenchain INEL/EG&G Idaho L.E. Hockreiter Westinghouse V.J. Esposito Westinghouse W.J. Johnson Westinghouse N.J. Laparulo Westinghouse W. Winkler GRS R. Jones B&W H.A. Bailey B&W J.J. Cudlin B&W W.T. Lanier GE-KAPL F.W. Lincoln Westinghouse - Bettis N. Fujita Energy Inc.
J. Guttmann NRC R. Audette NRC W. Hodges NRC B. Sheron NRC W. Lanning NRC/RSR W. Burchill CE J. Kapinos CE L. Agee EPRI D. Ross NRC
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