ML20246G263
| ML20246G263 | |
| Person / Time | |
|---|---|
| Issue date: | 12/09/1988 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-2611, NUDOCS 8905150239 | |
| Download: ML20246G263 (46) | |
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' Advisory Committee on Reactor Safeguards Thermal Hydraulic (T/H) Phenomena Subcommittee Meeting Minutes December 7, 1988 Bethesda, MD PURPOSE:
The purpose of the meeting is to review:
(1) the report of the once through steam generator technical advisory group, and (2) the final report of the NRC-RES Technical Program Group on the Code Scaling, Applicability and Uncertainty (CSAU) Evaluation Methodology.
ATTENDEES: Principal meet.ing attendees included:
ACRS NRC D. Ward, Chairman R. Lee, RES W. Kerr, Member L. Shotkin, RES l
C.-L Tien, Consultant B&W Owners Group P. Boehnert, Staff N. Trikotous B&W S. Nesbit T. Moskal LANL INEL B. Boyack G. Wilson BNL Sol Levi Inc.
W. Wulff J. Lellouche W
L. Hochreiter DESIGNATED ORIGIEAL
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T/H Phenomena Minutes December 7, 1988 MEETING HIGHLIGHTS, AGREEMENTS AND REQUESTS 1.
Dr. L. ' Shotkin (NRC-RES) provided ' overview comments on:
(1) the work of'the Technical Advisory Group (TAG) to develop a reportLon the need for research on OTSG T/H phenomena and, (2) the Technical Program Group (TPG) assembled by RES to develop the CSAU methodo-logy.
Dr. Shotkin reviewed the history of the cooperative NRC/B&W test program (MIST). He said that unresolved questions from MIST testing led to consideration of a OTSG test program. The principal concepts of the test program included:
(1)cooperativeeffort(50%
funded by industry up to a' total of approximately $4 million), and (2) testing needs defined through the TAG process.
Regarding the CSAU-process, there are plans to apply CSAU to the SB LOCA for a B&W plant using RELAP-5/M003.
Dr. Shotkin said this effort should " wrap up" LOCA research.for B&W plants.
2.
R. Lee provided introductory comments on the work of the OTSG TAG.
Dr. Catton asked for NRR to discuss (later) what use they see for the OTSG test data.
It, response to a request from Dr. Catton, Mr.
Lee said he would provide a copy of NRR's letter requesting OTSG test data.
Dr. Catton csked for an explicit statement of what phenomena need to be studied and just what use will be made of the data for the OTSG.
Figures 1-3 detail the objectives and background of the TAG effort.
The B&W OG agreed to fund a 50 % share of a test program, up to
$2M. The TAG membership is comprised of NRC/EPRI and B&W OG representatives.
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T/H Phenomena Minutes
. December 7, 1988 3.
Mr. N. Trikorous (GPU) discussed the conclusions / recommendations of the TAG effort. - The key conclusions of the TAG study were:
l-a.
A comprehensive list of 0TSG thermal-hydraulic phenomena can be developed using a top-down structure beginning with a plant state or condition and, progressing through a series of transients and processes, identify the underlying phenomena, b.
In general, the current state of knowledge regarding most phenomena important to OTSGs is sufficient; however, certain OTSG geometry dependent thermal-hydraulic phenomena were found to have data deficiencies, c.
Detailed sensitivity studies using best-estimate codes can and have been used to understand the importance of certain phenom-ena in OTSG performance. Using this approach, the following phenomena were found to be unimportant, even though geometry specific data was limited:
(1) AFW flog distribution (2) AFW spray' condensation d.
The following phenomena were found to have data deficiencies and were not resolvable by the use of sensitivity studies:
(1) Entrainment (2) De-entrainment (3) Liquid carryover (4) Void distribution above the mixture level (5) Phase separation (6) Decontamination factor (7) Flow-induced vibration
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T/H Phenomena Minutes December 7, 1988 The majority of these phenomena are important to the best-estimate analysis of rapid OTSG depressurization and/or excessive steam flow.
e.
Best-estimate transient predictions of SG depressurization, excessivesteamflow,andSGTR(dosecalculations)will require experimental data to develop and verify code models for the identified phenomena.
f.
For other 0TSG transients, it was found that an adequate data base exists upon which to base code improvemerits, if. required.
g.
~The verification of best-estimate. predictive models requires composite testing.
Separate effects testing may be required to generate data for model development.
Regarding item c Mr. Schrock and Dr. Catton questioned how a sensitivity study (ies) was able to resolve the issue of AFW wetting / spray condensation in the OTSG's. Mr. Knight (LANL) indicated that their analyses showed that these items did not impact the ther:nal level, the pool level (in the secondary) was controlling, assuming AFW is available. This item was discussed in more detsil below.
Mr. Schrock again raised a concern that the sensitivity studies are not going to address the question of developing a physical under-standing of the phenomena of interest. Tuning the code for a given phenomena (e.g., interfacial drag) is not a proper way of doing business. Dr. Knight indicated that the sensitivity studies were supposed to determine if a given parameter is worth pursuing or not.
T/H Phenomena Minutes December 7, 1988 I
Dr. Tien indicated that it will be very difficult to develop test i
data for such detailed phenomena as phase separation, etc. A more global test approach is needed.
Dr. Catton raised the issue of how the OG intends to deal with compensating errors in the codes; i.e., will they fix the codes?
Mr. Trikorous indicated that the TAG has not yet addressed the issue of how the data will be used.
The TAG made the following four recommendations:
a.
The TAG recommends an appropriate OTSG testing program be initiated if best-estimate code predictions involving the identified phenomena are desired.
b.
NRC research should obtain preliminary cost information on the various testing options.
c.
The NRC, BWOG, and EPRI sho'ild independently estimate the benefits to be obtained flom testing.
d.
A joint decision to participate in an OTSG thermal-hydraulic test program should be made based on cost-benefit considera-tions.
In response to Dr. Catton and Mr. Schrock, Mr. Trikorous indicated that the TAG does not now have a position on what kind of testing (separate effects vs integral) is needed.
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Mr. Ward asked how NRC will decide on the test program.
Dr.
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Shotkin indicated that a cost benefit study (ies) will be available from NRC.
Dr. Catton indicated that many of the the OTSG phenomena
-T/H Phenomena Minutes December 7, 1988 are generic; Dr. Shotkin indicated the next presentation will show how the phenomena of interest are related to the OTSG.
Mr. Ward said he sees the picture to be that a decision has been made that B&W T/H data is deficient vis-a-vis other vendors' data.
The next step is to determine if its possible to effectively add to the data base for a total of se$4M.
Dr. Catton questioned the need for a "0TSG" test given the univer-sal aspects of the phenomena. He said perhaps separate effects tests are needed here. Mr. Schrock indicated that the focus of the work should be on developing the needed constitutive equations for the codes. Mr. Ward indicated this type of effort may not be possible. Mr. Schrock indicated the above program direction probably won't be a good expenditure of money.
Dr. Tien said the TAG should define the test options available via-a-vis the data needed. Mr. Trikorous indicated that the TAG is
.1 now wrestling with the issue of running separate effects ar.d/or integral tests and the amount of money available will be the controlling factor.
A, The procets and results of the TAG effort were described by Mr. S.
Nerbit (Duke Power); Mr. Nesbit began by ntting the objectives and membership of the TAG.
A process diagram was shown which overviewed the TAG effort (Figure 4). The overall approach was to develop a comprehensive list of T/H phenomena applicable to OTSG behavior; from here one continual-ly screens out those phenomena based on sets of selection criteria.
Figures 5-7 detail the TAG process vis-a-vis phenomena compilation, and reduction by the various screening processes.
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T/H Phenomena Minutes December 7, 1988 Figure 8.provides a detailed description of the seven phenomena i
determined by the TAG to be most important for controlling the potential test facility design.
In response to Mr. Ward, Mr. Nesbit said there has'never been a SGTR in a B&W plant. Mr. Nesbit did say that a 1985 event at Davis-Besse probably resulted in some tube vibration. The Owners Group is investigating the issue of potential tube vibration Concerns.
5.
T. Moskal (B&W) discussed general concepts for the design of a composite (Integral)testfacility.
The facility characteristics were determined by:
(1) reviewing highest rated TAG phenomena, (2) describing the characteristics and measurementsneededforeach,and(3)prioritizingthesecharac-teristics.
For this presentation, Mr. Moskal discussed the'facili-ty needs vis-a-vis one of the phenomena of concern: de-entrainment.
Figures 9-11 detail the process used and the results.
Mr. Moskal noted that the chief advantage of an integral facility is that it would allow simultaneous investigation of multiple phenomena.
In response to Mr. Schrock, Mr. Moskal said the facility design now envisioned will be somewhat similar to the INEL OTSG air / water experimental facility, except that plant typical thermal conditions will be preserved.
Mr. Schrock raised a concern that the TAG had not adequately modeled the facility to obtain data on the phenomena of concern to them, given the deemphasis on certain facility characteristics; for example, data on entrainment/de-entrainment is dependent on the tube geometry vis-a-vis AFW wetting fraction. The OG indicated
4 a
T/H Phenomena Minutes December 7, 1988-that they will preserve the " flow per wetted tube" parameter which is the central phenomenon of concern.
The results of the ratings of facility characteristics are shown on Figure 11. The characteristics are listed.in descending order from most-to-least desirable.
The list of measurement requirements for the top seven phenomena of interest is shown on Figure 12.
In response to Mr. Schrock, Mr.
Moskal indicated that some of the requirements may not be feasible in an engineering sense (i.e., state of the art or beyond). The TAG has yet to determine the feasibility of these measurements requirements.
Conclusions of the above feasibility study were:
- Examination forms the besis for the cost / benefit analysis to follow.
Incremental costs of facility characteristics will be weighed ageinst each additional phenomena that can be inves-tigated.
- A composite facility designed to address the highest rated phenomena can be used to investigate lower rated phenomena, principally by additions to instrumentation and the test matrix.
- A composite facility would address individual phenomenon with local measurements, while preserving system conditions that cause the phenomena, and interactions among the phenomena.
The facility supports validation of system codes that must synthesize the analytical treatment of various phenomena.
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T/H Phenomena Minutes December 7, 1988 Mr. Moskal said the second bullet is somewhat comforting, if the importance of the phenomena as rated by the TAG is in error.
In response to Dr. Kerr regarding the cost / benefit study noted in the first bullet, Mr. Moskal said the " benefit" side of the equation will be different to the various group involved (NRC EPRI, etc.).
There was no discussion of separate effects testing as the TAG is not yet in agreement on an approach here. Mr. Ward asked how this decision will be made. Mr. Lee (RES) said this decision will be made outside the TAG. Mr. Nesbit indicated any decisions on the mix of integral / separate effect tests will have to await the cost / benefit study noted earlier.
Dr. Catton said that no money should be spent if the key phenomena of concern can't be captured via testing.
Mr. Jones (NRR) indicated the tests should be run if global pheno-mena can be obtained. Mr. Trikorous indicated the TAG /0wners are in a no win situation, as the limits on funding will open them up to criticism no matter which way they go.
lI 6.
Mr. Trikorous addressed future plans. He said the final TAG report will be issued in January 1989. Also, o meeting of the B&WOG, RES management, and EPRI is planned in January to discuss the TAG conclusions and recommendations. The cost / benefit study also needs to be completed in the near future to allow the process to proceed.
7.
R. Jones (NRR) provided NRR comments on the TAG process. The following points were noted:
NRC's concern was with a lack of adequacy of computer codes to predict B&W plant behavior.
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l T/H Phenomena Minutes December 7, 1988 1'
- The primary issue was lack of adequate data for modeling the OTSG.
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- The TAG process was effective in identifying most critical data needs.
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- The general facility concept proposed by the TAG appears appropriate.
Where possible, the. facility should be designed to provide data in other areas deemed lacking in data by TAG (e.g., AFW spreading / wetting).
Dr. Catton asked how the test data will be used by NRR in the end.
He doese.'t see how this program will be of use for the codes. Mr.
Schrock asked what the results of the INEL air / water test were used for. Mr. Wolf (EG&G) indicated that the INEL OTSG tests data is being used to upgrade the models in RELAP-5 so a "B&W version" of the code will be available. Mr. Schrock indicated that the current TAG approach will fall short vis-a-vis fixing the problems with the code.
As a result of further discussions, it was noted that the current consensus is that a full-scale OTSG test facility is not needed.
In response to further questions, Mr. Jones said NRR wants RES to tell them what problems / concerns the should be aware of for apply-ing B&W codes to licensing issues.
NRR expects the codes to be upgraded so they are useful to licensing; an alternative is that i
RES can detail the limitations of the (current) codes.
In response to Dr. Kerr, Mr. Jones indicated that upgraded codes could be used to relax (overly conservative) licensing restrictions.
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T/H Phenomena Minutes December 7, 1988 As a result of further discussion, Dr. Shotkin said the CSAU method will be applied to a SB LOCA for a B&W plant making use of MIST and (hopefully) OTSG follow-on data.
Mr. Ward asked for comment from the Subcommittee. He said the TAG has not fully concluded its work, and a decision to test will be nade soon, based largely on the TAG work. The Chairman asked what role the Subcommittee sees for the Committee in this process.
The Chairman said the Committee could provide comments on the process now, or wait until further information 'is available on the cost of a test facility (ies), the selection of separate effects versus integral effects tests, etc.
Comments received from the Subcommittee included:
Dr. Tien - Wait until the work of the TAG is complete; we need to hear how the test data will be used, and what tests (if any) are to be conducted.
Dr. Plesset - We need more input from the code developers as to what they see as their needs from the test program.
Mr. Schrock - We should encourage more NRR participation in the process to assure their concern /needs will be addressed.
Dr. Kerr - We should formally transmit the above comments to the affected parties.
[ Note: The Chairman proposed to discuss this issue with the ACRS at its December Meeting. He also proposes that the ACRS communi-cate with the Staff via a memo that the Committee wishes to be kept informed of the TAG decision milestones and be briefed on the status of the TAG effort at the January 1989 Comittee Meeting.
)
c T/H Phenomena Minutes December 7, 1988 Formal-comments on the OTSG test Program could follow the January briefing.]
8.
Dr. Zuber overviewed the Code Scaling Applicability and Uncertainty (CSAU) Methodology. The objectives of CSAU are:
(1) Provide a technical basis for quantifying uncertainty within the context of the revised ECCS rule.
(2) Provide an auditable, traceable and practical method.for combining quantitative analyses and expert opinion to arrive at a computed value of uncertainty.
(3) Provide a systematic and comprehensive approach for:
a.
Defining scenario phenomena b.
Evaluating code applicability c.
Assessing code scale-up capability d.
Quantifying code uncertainty related to:
- Code and experiment accuracies
- Code scale-up capabilities
- Plant state and operating conditions.
Figure 12A lista the members of the RES Technical Program Group (TPG) that developed and demonstrated CSAU. The TPG effort con-sumed 117 man-months of time. Dr. I. Catton was an ACRS observer to the meetings of the TPG.
Regarding the development of a simple physical model (see below),
Dr. Zuber said it was not the intention of the TPG to provide a simple model for use in the licensing process; rather the simple model was developed to synthesize the knowledge gained over the
(
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'T/H Phenomena Minutes December 7, 1988-q last 15 years of LOCA research and to assure transfer of this knowledge for futura use. Three simple models were developed to calculate the:
(1) PCT, (2) effect of ECC bypass on PCT, and (')
d effect of steam binding on PCT.
Dr. Zuber said the " moral" of the LOCA research effort is that given:
(1) an extensive experimental data base from well scaled' facilities and well designed tests, and (2) close integration of experiments and analyses, closure of the LB LOCA issue was possi-ble.
In response to Dr. Tien, Dr. Zuber said the fact that the LOCA test facilities were well scaled, and there also was a full-scale test facility available (UPTF) assured resolution of the LB LOCA issue.
In response to Mr. Ward, Dr. Zuber said the CSAU exercise illu-minated problems with the code and also allowed one to determine
'the uncertainty associated with revising a code model. He said that the codes can always be improved, but indicated that from a cost effectiveness standpoint they are sufficient.
9.
B. Boyack (LANL) overviewed the CSAU method.
Figure 128 shows a schematic of the CSAU methodology.
The method is comprised of three subelements and 14 steps. The subelements are:
(1) require-ments and code capability, (2) assessment and ranging of parame-ters, and (3) sensitivity and uncertainty analysis.
Figures 13-25 provide a summary description of the method.
The results of the total uncertainty for the PCT LB LOCA calcu-lation performed are given on Figure 26. The 95% probability PCT l
calculated was 1572 F.
Mr. Boyack said the demonstration for the LB LOCA shows the method to be auditable, traceable, and practica-ble.
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1.
e T/H Phenomena Minutes December 7., 1988
.In. response to Dr. Plesset, Dr. Wulff (BNL) said the CSAU method is code-and scenario-specific. Details of the demonstration will be different for different scenarios and plants.
Mr. Ward indicated some concern that the above PCT figures may be misused.
Dr. Boyack said it is up to the TPG (and NRC) to assure this does not occur.
10.
G. Wilson (INEL)detailedthefirstCSAUsubelement:
" identify requirements and code capabilities" (for the scenario and code of interest).
Wilson's presentation focused on the identification and-ranking of key phenomena that must be evaluated in the CSAU process. This ranking procedure is basically determined by expert opinion /engi-neering judgment.
In response to Mr. Schrock, Mr. Wilson said the TPG did evaluate the effect of combined minor errors associated with parameters considered of minor importance. Mr. Wilson indicated that a
" checks and balance" approach of sorts was used, as the code results were compared to data.
Further discussion resulted in the consensus opinion that the CSAU method has reduced the uncertainty associated with calculation of-LB LOCA parameters to a level that is probably a good as can be obtained absent another major research effort, and is certainly sufficient to close out the LB LOCA issue.
- 11. The second CSAU subelement:
" assessment and ranging of parameters (Steps 7-10) was detailed by W. Wulff (BNL). Dr. Wulff noted that the experimental data base supporting the identified phenomena is defined and used to range the variability in the individual L-__--___--_____-_----_.
i T/H Phenomena. Minutes December 7, 1988 i
i parameters.
In addition, Dr. Wulff discussed data sets and their use to support the plant model nodalization selection, investigate code accuracy, and scale uncertainty. The results from this element form the basis from which the uncertainty in the primary safety criteria is developed as noted below.
12.
J. Lellouche detailed the last CSAU subelement that addresses the quantification of the uncertainty evaluation for the LB LOCA analyses.
He described the analysis to calculate'the bias and l
uncertainties associated with the PCT parameters. The results of the PCT calculations were also provided.
Figure 27 shows the final estimate of LB LOCA PCT uncertainties.
The 95% PCT value calcu-lated was 1572 F.
Other analyses performed show that TRAC calcu-lations of PCT are consistently conservative vis-a-vis test data.
13.
G. Wilson discussed the development of a physically based (simple) model for estimating PCT.
[ Note:
Dr. I. Catton was recused from participation due to C0I, for this presentation.]
The method devised provides a straightforward engineering method for estimating PCT based on three' design parameters. These parame-ters are:
(1) peak linear heat generation rate, (2) blowdown cooling time, and (3) core cold reflood rate.
From these, four correlations are developed. These correlations calculate:
The first temperature peak due to stored and decay heat - less blowdown heat removal due to DNB and post-dryout cooling.
- The temperature decrease during blowdown resulting from forced convection cooling.
The temperature rise, during refill.
l
4 T/H Phenomena Minutes December 7, 1988 The temperature rise during reflood resulting from decay heating.
The model also accounts for uncertainty.
Compari. sons with the TRAC
~
analyses discussed above show very good agreement.
Mr. Wilson said these results confirm the validity of the CSAU method.
In response to Mr. Ward, Mr. Wilson indicated that similar work had been done years ago, but it u not accepted by the pier "communi-ty" at that time.
Dr. Plesset commented that he is favorably impressed with the above analysis.
14.
L. Hochreiter (W) provided W comments on the CSAU methodology.
Key point noted by Dr. Hochreiter included:
Westinghouse congratulates the NRC, INEL, LASL, BNL, and TPG members for the successful conclusion of the large break LOCA CSAU effort.
CSAU has provided the NRC and industry with a logical, consis-tent approach which can be a starting point for best estimate computer code licensing. However, we believe that additional effort will be required in the actual licensing of a power plant.
" Our recent experiences in licensing WCOBRA/ TRAC indicate that resolution of uncertainty issues is achieved by addressing all possible sources of uncertainty (not just the most important ones from a ranking table as was done by the TPG). Thus, a
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T/H Phenomena Minutes December 7, 1988 CSAU approach where all uncertainties are completely treated may be unworkable.
k'hile CSAU has provided a licensing path, we believe addi-tional work will be necessary in licensing a best-estimate code.
In response to questions from the Subcommittee, an NRR representa-tive (Mr. G. Hsii) indicated that the CSAU method should be useful in identifying items that need to be addressed for BE LOCA analy-ses.
Dr. Zuber expressed pleasure that industry is interested in CSAU and he agrees with Dr. Hochreiter that more work is needed.
- 15. Mr. Ward asked for comments from the Subcommittee.
There~was general consensus that the RES effort on CSAU was well done and the ACRS should be briefed.
Dr. Catton and Mr. Schrock indicated that NRR should make use of CSAU to focus on key parameters and limit the calculations needed l
on parameters known to be unimportant (i.e., their uncertainty is i
I small).
1 i
i The Subcommittee praised NRC RES for a job very well done for the I
l development and demonstration of the CSAU method.
It was also I
l agreed that this topic should be presented to the ACRS at its
)
l December meeting. The Subcommittee also recommended that NRR make a presentation as well focusing on their intended use of CSAU via-a-vis the ECCS evaluation model licensing process.
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- 16. The meeting was adjourned at 5:15 p.m.
l
T/H Phenomena. Minutes December 7, 1988
. N0TE:
Additional meeting details can be obtained from a transcript of this meeting available in.the NRC Public Document Room, 2120 L Street, N.W., Washington, D.C. 20006, (202) 634-3273, or can be purchased from Heritage Reporting Corporation, 1220 L.' Street, N.W., Suite 600, Washington, D.C. 20005,(202) 628-4888.
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Once Through Steam Generator (OTSG)
Technical Advisory Group (TAG)
Objectives:
(a) To investigate the thermal-hydraulic issues related to OTSG.
(b) To identify whether additional experimental data was needed, and if necessary, define the required experimental design concept (s).
1 ACRS T/H Subcomm. 12/7/88 l
b
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===.
Background===
Letter of Agreement On October 2,1987, NRC, EPRI and the B&W Owners Group (B&WOG) agreed to form a TAG to determine the need for additional experimental data to confirm OTSG thermal-hydraulic phenomena.
B&WOG agreed to contribute S200,000 to the MIST Phase-IV~
program.
TAG will recommend to the Program Management Group regarding the need for additional tests; and if testing is required, the general concept to be followed in test facility design. The industry will fund a 50% share of the resulting recommended testing (if any) up to a total of S2 million.
ACRS T/H Subcomm. 12/7/88
/W/-9]
Background (Continued),
Guiding Principles for TAG 1
Define phenomena related to OTSG performance.
Rank phenomena according to importance to understanding transient or accident behavior.
Assess existing / planned data base for important phenomena to identify any deficiencies.
Define means of resolving deficiencies.
Issue TAG Report.
ACRS T/H Subcomm. 12/7/88
o e
TAG PROCESS DIAGRAM COMPREHENSIVE PLANT /OTSG l
APPLICATIONS j
(TRANSIENTS)
CONDITIONS rrmm. su.m:m BREAKDOWN q
INTO p
PHENOMENA I!
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_ SELECTION lNO DOCUMENT E
I CRITERIA l
REPORT YES M
v REDUCED PHENOMENA LIST
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AVAILABLE SENSITMTY DATA STUDIES NO NEED FOR ADDITIONAL DATA YES y
DETERMINE METHOD TO OBTAIN DATA v
REPORT l Iw '/]
a TAG Process Phenomena Compilation and Reduction Lists of phenomena were generated by different e
organizations using various methods INEL -
Phenomena based on processes during various transients EPRUB&WOG -
Phenomena based on constitutive relations in transient analysis codes B&WOG-Phenomena based on conditions during various transients B&W -
Issues and phenomena based on events and items of current interest e
The phenomena from the various sources were collected into a comprehensive list 1
f-The comprehensive list was reduced by eliminating those e
which, by consensus agreement, are not important to transient behavior, or covered by the existing data base
4 TAG Process Phenomena Rating and Generic Item Consideration Each phenomenon was assigned a 0-5 rating to reflect the e
relative importance with respect to plant transient behavior, with 5 signifying tae most important An evaluation was made of the generic nature of all of the e
phenomena, and the generic items were removed from further consideration (Generic items are those which are important to all reactor designs, not solely or especially B&W plants)
Each of the remaining phenomena were assigned a 0-5 e
rating to reflect the adequacy of the existing data base, with 5 signifying the least adequate o
The remaining phenomena were given combined ratings by multiplying the importance and data base ratings eg.
HY1B De-entrainment Importance rating = 5 Data base rating = 4.5 Overall rating = 22.5
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TAG Process I
Further Reduction of Phenomena The results of the various analyses and sensitivity studies e
were used to re-evaluate the importance rating for the appropriate phenomena LANL studies of boiler-condenser cooling, SG overfill, and steam line break
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INEL studies of natural circulation, SG overfill, and steam line break B&WOG plant benchmarks B&WOG 3D studies of the OTSG in natural circulation with EFW Revised overall ratings were generated based on the new e
importance ratings for two phenomena, HT10 (Condensation on AFW Spray) and HY8 (AFW Flow Distribution) l
/*1
TAG Results The following seven phenomena were identified by the TAG as most important for determining potential test facility design:
HY1B -
De-entrainment ofliquid from the flow stream by tube support plates and the path to the steam lines HY6 -
Carryover of liquid into the steam lines HY15 -
The void distribution above the secondary side mixture level HY9 -
Phase separation or the dynamic response of the SG mixture region during various upset conditions HY12 -
Decontamination factor or the retention ofiodine in the SG secondary side HY1A -
Entrainment ofliquid into the vapor stream HY10 -
SG tube flow-induced vibration 4
I OTsG SECTION AT AUXILIARY FEEDWATER NOZZLE l
PRIM ARY INLET f
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OTSG SHELL TUBE BUNDLE l
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TO STEAM OUTLET Deentrainment Mechanisms e
Transverse turbulence as fluid flows vertically through tubed region e
Impingement on structure at flow area constrictions, such as tube support plates e
Centrifugal force and tube impingement as flow turns horizontally toward exit and traverses the tube bundle m
$$. Y
Facility characteristics needed to investigate deentrainment:
Prototypic tube support plates Required (2) 4 and exit geometry Depth of tube array sufficiently Required (2) large to support regional effects (wetting, superheating), and exit turn effects Full power per tube Required (1.5)
Transient capability Required (2)
Full elevation Desired (0.5)
Prototypical auxiliary feedwater Desired (i) characteristics Tube array dimensions sufficiently Required (2) large to suppress wall effects Responsive, controllable primary Desired (i)
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CSAU PROGRAM ORGANIZATION A TECHNICAL PROGRAM GROUP (TPG) WAS FORMED IN FEBRUARY OF O
1987, TO IMPLEMENT AND DEMONSTRATE THE CSAU METHOD.
O TPG MEMBERS:
BNL:
U. ROHATGI AND W. WULFF INEL:
R. DUFFEY, K. KATSMA AND G. WILSON LANL:
B. BOYACK AND H. SULLIVAN SLI:
G. LELLOUCHE AND S. LEVY MIT:
P. GRIFFITH NRC:
D. BESSETTE AND N. ZUBER 0
TPG MEETINGS ATTENDED BY:
- 1. CATTON, ACRS CONSULTANT '
CSAU EVALUATION METHODOLOGY ELEMENT 1 sta:Y REQUIREMENTS l gyte.'NO l1 E
AND CODE f
CAPABILITIES T
SILTCT l 2 Pit 0VIDI COWPLf7C DOCUWInffATiON MPP i
C00tWAmv4L 4
PROGRauw $ Ul0C 5
DCYCLOPWENT & OTMtR A55CS$WINT l 'NI" ' Es f(
l.3 WCDEL & CORRELATIONS DI R
I i
4 erTrnwiwt CODI 6
APPLICA$1LITY 157A9Lisw ELEMENT 2 A5[L,5,y', twt 7
ASSESSMENT d
AND RANG!NG PARAMETERS Otrs=t
- *lll{*"
CALCULATIONS 4
4 COWPAtt CALCULA* ION $
COWPART CALCULATIONS VS. Sti$ U$1NO %PP
$[1 l
l(1 V$.$tTS USIACNPP
_g NODAL 2AY104 DATA B A$t l CATA BA$(
h00AU2&Tl0N f
00CvutNi DOCuwtNT l
I Effai no owYtaf'8Tv b I !EI[R,ib!N 9
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Drit'N'*t l UNCERTAINTY l+--
if, 10 r
}
t ELEMENT 3 s.As Awa y
$fN75[Iw"PS 33
'N'"$3fr}s f'
SENS71VITY AND UNCERTA!NTY 4
ANALYS!S PERr0Ru NPP scusmvrry 12
{
CALCULATIONS 4
r -tovssnr---:
13 !
.A W iF L !
co"'Lf'5t5 v= tuiwrties L;;;^';o; a
- ..... c.o?.t: !E..... :
4 TOTAL UNCCRTAleiTY.
l 10 CALCULAtt SPCCir C SCthARio 14 lh A
$PCCiric WPP LOS ALAMOS 12/7/88 4
ELEMENT 1 REQUIREMENTS AND CODE CAPABILITIES
- SELECT ~
O SCE 4 R O OD I I 1f SELECT LPROVIDEA COMPLETE ~.
2
-NPP SET OF DOCUMENTATION
" CODE MANUAL"
< USERS. GUIDE 5
1 y 3
PROGRAMERS GUIDE:
' DEV. ASSESSMENT DOC.
IDENTIFY MODEL' & CORRELATIONS DOC.
AND RANK PHENOMENA l
1 r DETERMINE CODE 6
APPLICABILITY I f PROCEED TO ACTIVITIES IN ELEMENT 2 ASSESSMENT AND HANGING OF PARAMETERS LOS ALAMOS 12/7/88 6
1
'i j
CSAU DEMONSTRATION STEP 1 - SCENARIO SPECIFICATION Cold-Leg Large-Break LOCA STEP 2 - SELECT NUCLEAR POWER PLANT GENERIC WESTINGHOUSE RESAR-3S
. Four-Loop 193 Fuel Bundles in 17 X 17 Array 3411 MWT, Normal Full-Power
. Midlife Of Second Fuel. Cycle 1
STEP 4 - SELECT FROZEN CODE TRAC-PF1/ MOD 1, VERSION 14.3 (frozen)
. STEP 5 - PROVIDE CODE DOCUMENTATION
. Code Manual: NUREG/CR-3858
. User Guide: NUREG/CR-4442
. Assessment Reports Developmental: NUREG/CR-4278 Other: Extensive Bibliography
. Models and Correlations Quality Evaluation Document : NUREG/CR-5069 (Dec.1988)
LOS ALAMOS 12/7/88 7 l
J P//M]
l ELEMENT 1 REQUIREMENTS AND CODE CAPABILITIES SELECT SPECIFY 1
FROZEN 4
SCENARIO CODE t
I I 1f SELECT PROVIDE A COMPLETE 2
NPP SET OF DOCUMENTATION CODE MANUAL USERS GUIDE 5
1 g 3
PROGRAMERS GUIDE DEV. ASSESSMENT DOC.
IDENTIFY MODEL & CORRELATIONS DOC.
AND RANK PHENOMENA I
V DETERMINE CODE 6
APPLICABILITY 1 I PROCEED TO ACTIVITIES IN ELEMENT 2 ASSESSMENT AND RANGING OF PARAMETERS l
LOS ALAMOS 12/7/88 8 S
j
~
STEP 3
~
IDENTIFY AND RANK PHENOMENA Ranking of LBLOCA Phenomena Highly Phenomena identification Ranked Phenomena N
Break flow N
Phenomena Stored energy identified For Each and fuel Of The Following response Components Fuel Rods Core Experts Upper Plenum Group Hot Leg Pressurizer Steam Generator 7
i Pump Pump two phase Cold Leg Accumulator flow Downcomer Lower Plenum g
Bmak Hierarchial Loop Steam binding Process (reflood only)
Blowdown Phenomena forty one identified Refill / Reflood Phenomena F
by forty six identified
,gn Non condensible gas LOS ALAMOS 12/7/88 9 s
f/6 //
STEP 6 DETERMINE CODE APPLICABILITY l
FROM STEPS 1 - 3 FROM STEPS 4 - 5
- SCENARIO, CODE PLANT AND AND KEY KEY PHENOMENA DOCUMENTATION IDENTIFIED PROVIDED 1 P
~
DETERMINE CODE 6
APPLICABILITY.
I ACTIVITIES COMPARE CODE CAPABILITIES TO IMPORTANT TRANSIENT AND 1
PLANT REQUIREMENTS l
. REVIEW FIELD EQUATIONS l
(GLOBAL PROCESSES)
. EXAMINE CLOSURE EQUATIONS
. EXAMINE ABILITYTO MODEL i
COMPONENTS AND CONTROL
. IDENTIFY DEFICIENCIES
. JUDGE APPLICABILITY V
PROCEED TO ACTIVITIES IN ELEMENT 2 ASSESSMENT AND RANGING OF PARAMETERS LOS ALAMOS 12/7/88 10 lFM-l7)
ELEMENT 2 ASSESSMENT AND RANGING OF PARAMETERS FROM ELEMENT 1
~ ESTABLISH
" ASSESSMENT -.
)
MATRIX t
DEFINE _
NODALIZATION 4
FOR NPP CALCS I
t COMPARE CALCS VS.
COMPARE CALCS VS.
SET IET
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NO%LIZATION '
g BASF-BASE DOCUMENT '-
DOCUMENT
~
I l
V NODI HAN NO f
BIAS AND DETERMINE CODE AND 9
2 UNCERTAINTY EXPERIMENT ACCURACY
'f 10 BIAS AND 2
DETERMINE EFFECT UNCERTAINTY L' OF SCALE I I TO ELEMENT 3 SENSITIVITY AND UNCERTA!NTY ANALYSIS LOS ALAMOS 12/7/88 11 i
l STEP 7 ESTABLISH ASSESSMENT MATRIX
- lDENTIFY APPLICABLE SEPARATE EFFECT TEST (SET) AND INTEGRAL EFFECT TEST (lET) FACILITIES AND DATA IMPORTANT PHENOMENA (Step 3)
SCALING ISSUES (Step 10)
NODING ISSUES (Step 8)
. CODE DEFICIENCIES (Step 9)
PARAMETER RANGING (Steps 9,10,11)
DATA FROM 31 FACILITIES USED IN CSAU DEMONSTRATION STEP 8 DEFINE NODALIZATION FOR NPP CALCULATIONS CONSIDERED THE FOLLOWING SUFFICIENT NODING TO REPRESENT IMPORTANT PHENOMENA AND DESiCN CHARACTERISTICS OF THE NPP COARSE ENOUGH TO REMAIN ECONOMICAL BASED NODING DECISIONS ON PREVIOUS ASSESSMENT EXPERIENCE NODALIZATION STUDIES REVIEW OF EARLY NPP CALCULATIONS ESTABLISHED A STANDARD NODING FOR ALL CSAU CALCULATIONS (PARAMETER RANGING USING SET AND IET DATA AND THE NPP CALCULATIONS)
LOS ALAMOS 12/7/88 12
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ELEMENT 2 ASSESSMENT AND RANGING OF PARAMETERS FROM ELEMENT 1 ESTABLISH ASSESSMENT MATRIX t
DEFINE NODAUZATION 4
FOR NPP CALCS I
t t
COMPARE CALCS VS.
COMPARE CALCS VS.
SET IET lETS USING NPP SETS USING NPP NODALIZATION DATA DATA +
NODAUZATION g
BASE BASE DOCUMENT DOCUMENT I
I NODING hat NO I I BIAS AND DETERMINE CODE AND _
9 2
UNCERTAINTY EXPERIMENT ACCURACY.
'f 10 BIAS AND DETERMINE EFFECT UNCERTAINTY '
c OF SCALE I f TO ELEMENT 3 SENSITIVITY AND UNCERTAINTY ANALYSIS LOS ALAMOS 12/7/88 14 f/hM]
STEPS 9,10,11 DETERMINE EFFECTS (CODE / EXPERIMENT ACCURACY, SCALE, REACTOR INPUT)
USING SET AND IET DATA DETERMINE RANGES OF CODE PARAMETERS IDENTIFIED, OR
- QUANTIFY BY BOUNDING ARGUMENTS (SEPARATE BIASES ONLY)
STEP 9 DETERMINE CODE SEPARATE BIASES RANGED PAR AMEMRS EXPERIMEt ACCURACY
. CODE ACCURACY IMPLEMENTATION
. BREAK FLOW OF FORSLUND-BREAK DISCHARGE ROHSENHOW 1f STEP 1C COEFFICIENT DETERMINE STEAM BINDING EFFECT OF STORED ENERGY AND INTERFACIAL DRAG FUEL RESPONSE SCALE CORE GAP CONDUCTANCE UF PLENUM PEAKING FACTOR HOT LEGS FUEL CONDUCTIVITY HEATTRANSFER COEF.
l
. ECC BYPASS 1 f STEP 11 INTERFACIAL DRAG DOWNCOMER DETERMINE EFFECT OF
. PUMP TWO PHASE FLOW i
REACTOR INPUT HOMOLOGUS CURVES PARAMETERS AND STATE 1 I INDIVIDUAL UNCERTAINTIES TO BE COMBINED BY GENERATING A RESPONSE SURFACE AND DETER-MINING A PROBABILITY DISTRIBUTION FUNCTION USING MONTE CARLO TECHNIQUES 1 P INDIVIDUAL UNCERTAINTIES ARE TREATED AS SEPARf4TE BIASES (PENALTY OR BENEFIT) AND COMBINED BY ADDITION LOS ALAMOS l
12/7/88 15 h*Y
~
ELEMENT 3 SENSITIVITY AND UNCERTAINTY ANALYSIS FROM ELEMENT 2 ASSESSMENT AND RANGING OF PARAMETERS Y
ll BIAS AND DETERMINE EFFECT OF b
-b REACTOR INPUT UNCERTAINTY PARAMETERS AND STATE V
PERFORM 12 APP SENSITIVITY CALCULATIONS V
' ADDITIONAL 'l 13 l MARGIN IF 'l l
COMBINE BIASES
- UNCERTAINTIES.
y WARRENTED BYj AND
. LIMITATION IN l
DATA BASE, : l L. CODE, ETC -
-__J Y
TOTAL CERTAINTY i
TO CALCULATE A SPECIFIC SCENARIO I
IN A SPECIFIC NPP LOS ALAMOS 12/7/88-16
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ELEMENT 3 SENSITIVITY AND UNCERTAINTY ANALYSIS FROM ELEMENT 2 ASSESSMENT AND RANGING OF PARAMETERS Y
ll BIAS AND DETERMINE EFFECT OF b
-b REACTOR INPUT UNCERTAINTY PARAMETERS AND STATE i f PERFORM 12 l
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. SPECIFIC SCENARIO
- IN A SPECIFIC NPP -
LOS ALAMOS 12/7/68 18
-n
- := - -
- = =
o
-,c TOTAL UNCERTAINTY FOR THE CSAU DEMONSTRATION
- PCT (F)
~
^~
BLOWDOWN REFLOOD 1st Peak 2nd Peak MEAN PCT 1162 978 758 (Combined Uncertainty by PDF) 95 % PROBABILITY 1447 1399 1336 (Combined Uncertainty by PDF)
MEAN SEPARATE BIASES ADDED Hot Channel Effects 63 25
-14 Dissolved Nitrogen N/A 18 18 l
l Nonconservative implementation 47 84 160 of Forsland Rohsenow Correlation Full Scale Steam Binding Effects N/A
-9 106 Full Scale ECC Bypass Effects N/A
-34
-34 COMBINED MEAN BIASES 110 84 236 i
TOTAL MEAN PCT 1272 1062 994 (including combined biases)
TOTAL 95 % PROBABILITY PCT 1557 1483 1572 i
(including combined biases)
- Application to a four-loop Westinghouse PWR for a cold-leg LBLOCA and using TRAC-PF1/ MOD 1, Version 14.3 LOS ALAMOS i
12/7/88 19
$~ ) }
0-e" Table 17 ESTIMATE OF TOTAL LBLOCA UNCERTAINTIES PCT (*F)
Reflood Source Blowdown IElX 1At.1 TRAC Response Surface Mean 1162 978 758 95th 1447 1399 1336 Summed Biases:
110 84 236 Adjusted Mean 1272 1062 994 Adjusted 95th 1557 1483 1572 O
a i
4