ML20148K056
| ML20148K056 | |
| Person / Time | |
|---|---|
| Issue date: | 12/01/1987 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-2537, NUDOCS 8801270539 | |
| Download: ML20148K056 (43) | |
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THERMAL HYDRAULIC PHENOMENA SUBCOMMITTEE MEETING MINUTES NOVEMP,ER 18-19, 1987 WASHINGTO.,, D.C.
PURPOSE: The purpose of the meeting was to review key elements of NRC-RES's Five-Year Thennal Hydraulic Research Prooram for input to a proposed ACRS Report on thermal hydraulic r^ search. The Subcomittee also discussed the status of NRC's action on a potentially unanalyzed
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large-break LOCA scenario.
ATTENDEES:
ACRS FRC D. Ward, Chairnn B. Sheron, RES J. Ebersole, Member L. Shotkin, RES G. Reed, Member (18th only)
R. Lee, RES I. Catton, Consultant D. Solberg, RES V. Schrock, Consultant Y. Chen, RES C-L. Tien, Consultant D. Bessette, RES N. Lauben, RES C. Rhee, RES N. Zuber, RES W. Lyon, NRR R. Jnnes, NRR A complete list of attendees is attached to the Office of copy of these minutes.
MEETING HIGHLIGHTS, AGREEMENTS, AND REQUESTS:
1.
Mr. Ward said the Subcomittee should focus on how the T/H research program is servicing the agency's Strategic Plan. He said our coments should reflect on NRC's overall goals. Mr. Ward said the rema'ning goal
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of the T/H research now under way should be to aid the uncertainty analyses in support of the CSAU effort.
Mr. Reed said a diverse DHR method is needed. Research on a blowdown system is lacking and the B&W approach of increasing pressure is the wrong.:ay to go. Mr. Ebersole said NRC Research should be involved in the effort on feed and bleed vis-a-vis LOCA research.
8801270539 971201 _
DESIONATED ORIGIHAL AN PDR 2
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MINUTES OF THE THERMAL HYDRAULIC-NOVEMBER 18-19, 1987 SUBCOMMITTEE MEETING Dr. Catton said the T/H Five-Year Plan (NUREG-1252) seems to have a number of inconsistencies that RES should address in their presentation.
2.
W. Lyon (NRR) presented the status of the NRR effort en the unantly7ed LOCA' scenario. A10CFR50.54(f)lettertoIndustryisunderinternal review in NRR. When complete, the ACRS will be consulted. The problem (loop seal plugging) is applicable to W and to a lesser extent, Ct.
plants.
The B&W plants are not subject to this concern. A meeting with the WOG was unsatisfactory as the WOG saw no need to address this issue.
NRC-Rasearch has not been able to dismiss the concern out-of-hand. The core melt risk contributor is considered low however given the low probability of the accident conditions required.
i In response to Mr. Ward, Mr. Lyon said the 50.54(f) Letter would require investigation of the T/H phenomena involved and how the Licensee would assure compliance with the regulations.
In response to Mr. Ebersole, Mr. Lyon said it is believed that hot-leg injection may alleviate this problem.
In response to Mr. Boehnert, Mr. Lyon said Connission notification is being delayed, pending a : lear understanding of the seriousness of the issue.
3.
Prior to Dr. L. Shotkin discussions on the future plans for T/H re-search, Dr. Catton noted that there seems to be e disconnect between the future plans of NRC Research and what's in NUREG-1252. Also, code development seems to be forever ongoing. Mr. Schrock complained that there is a lack of basic data needed to fix the codes, but this issue is j
not addressed in the Five-Year Plan.
Dr. Shotkin noted that the Agency has initiated a new approach where all senior managers meet to review the goals of the agency's Strategic Plan.
He noted the following observations:
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MINUTES OF THE THERMAL HYDRAULIC NOVEMBER 18-19, 1987 SUBCOMMITTEE MEETING T/H has a low priority in the Agency. There is very little overall Agency interaction with the T/H research Program.
T/H research is related to reactor design. The emphasis on reactor operations will result in less of a need for T/H work. The focus in the future will be on operations-related problems, particularly the human factors element of operations.
l T/H will play a lesser role in research and will probably be rele-gated to an on-call basis with an ongoing minimal level of support.
In response to Dr. Catton, Dr. Shntkin said there will be a need for T/H research and applications, but T/H won't be the key player it once was.
Dr. Catton said that the flavor of NUREG-1252 will need to be recast to reflect the above goals.
The Strategic Plan (SP) and Five-Year Plan were discussed. The research philosophy in the SP focuses on the need for independent expertise and to anticipate problems.
In response to Mr. Ward, Dr. Ehotkin said the key problem will be the retention of knowledgeable people for when they are really needed (i.e., a big accident).
Dr. Tien disagreed that there are not intere= ting T/H-related issues that need to be addressed (e.g., operatinns), but what is really needed is a rethinking of priorities.
T/H research will be assigned priorities and risk assessment will be instrumental in detennining these priorities per the SP.
The 5-Year Plan includes a topic labelled Plant Performance (T/H), Human Perfonnance, and Accident Management which are all incorporated together.
Fromthe5-YearPlan,theBranchPlan(NUREG-1252)was developed, m
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MINUTES OF THE THEPEAL HYDRAULIC NOVEMBFR 18-19, 1987 SUBCOMMITTEE MEETING The future plans for T/H research were reviewed. The regulatory applications of T/H research focus on the prevention or minimizing of core damage through the understanding of T/H perfomance under accident conditions.
Figure 1 shows a list of T/H regulatory issues.
In response to Mr.
Ebersole, Dr. Sheron indicated that depending on the issue at hand, RES may or may not be coordinating their work with NRR. He also said that T/H research will have a major change in emphasis, and will not neces-sarily be phased out.
TheRegulatoryRecuirementsReviewGroup(RRRG)wasdiscussed.RRRG coordinates the research needs of NRP/AE0D, RES, etc. Dr. Sheron said the RRRG has been very successful.
Dr. Catton said RES needs to develop a T/H laboratory in the U.S. and keep it in continuous operation, rather than surplusing equipment and manpower or going overseas to run tests.
Current and future research users include NRR, AE00, and the Regicaal Offices. Research plans to issue comprehensive reports that synthesize the results of disparate prcgrams. Reports are underway on the topics of feed and blead and natural circulation.
In addition, RES will use the T/H codes in support of major research programs. The future structure of the T/H research Branch will subdi-vide along the lines of "research" and "applications" (of the research).
Most major T/H programs (ICAP, 2D/3D, ROSA IV, MIST, Codes, etc.) will be completed by the end of CY 1991.
RES sees no reed at this time for a new integral facility, but this positiun will be reviewed from time to time.
l Baseline programs will continue for the plant analyzer, the INEL TSC and basic studies. Code development and assessment efforts will decline to o
MINUTES OF THE THERMAL HYDRAULIC NOVEMBER 18-19, 1987 SUBCOMMITTEE MEETING a baseline level and efforts will be continued to make code improvements as necessary. New prooram initiatives include:
International Code Consortia Accident Management Codes (Front End)
Improved NRC-Owned Simulator Perfonnance B&WOTSGTesting(WithIndustry)
ScalingofTestingFacilities(CEC,UNCP)
Support to Regional Inspectors Multi-Disciplinary Approach to Issue Resolution Technical Support Center at INEL In response to Mr. Ward, Dr. Shotkin said a synthesis report will be written on the topic of test facility scaling.
In reply to Mr. Reed, Dr. Shotkin indicated that no further work is planned on the study of feed and bleed T/H phenomena via such issues as two-phase flow through valves (PORVs, etc.). Dr. Sheron indicated that feed and bleed is not a licensing requirement. Mr. Reed asked how NRR would review the Davis-Besse enhanced feed and bleed system absent research on the T/H of feed and bleed. Mr. Jones said there are no regulatory requirements for feed and bleed.
Further discussion brought out the concern that the PORVs have not been quali#ied for feed and bleed duty. NRC noted that feed and bleed is beyond the design basis.
Comenting on the 5-Year Plan, Dr. Tien said RES needs to show how the old and new prcgrams will relate to the Strategic Plan. Dr. Shotkin indicated that the proposed Accident Management Plan will address the integration of the new programs. RES does not see any major issues that are not being, or have been, addressed. Dr. Tien noted that he does not see any initiatives in such areas as computer aided software for reactor oparations. Dr. Shotkin indicated that such items are to be addressed in the ongoing Accident Management Plan.
Dr. Catton said the Subconnit-tee should review these other plans so we'll have the whole. picture.
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MINlJTES OF THE THERMAL HYDRAULIC NOVEMBER 18-19, 1987 SUBCOMMITTEE MEETING l
4 Mr. Ward said the Subcommittee needs to think further on the bounds of its review.
Mr. Ward suggested that RES look at the idea of factoring in the experi-ence and research results to a reevaluation of the design basis acci-dents. He indicated that NRL needs to revise and update its regulations j
(e.g.,theECCSrequirements). Dr. Shotkin agreed this effort should i>e j
pursued and he will look into this.
Dr. Sheron noted that a risk-based approach to DBAs is very difficult -to evaluate and any industry subnit-tal would result in an argument over numbers. Another problem is establishing a "DBA" for containment (i.e., a severe accident).
i Revisiting of the DBAs needs to await the establishment of the severe accident policy. Mr. Ward indicated that the current knowledge base should allow opportunity for interesting work in this area, but the will to act seems to be lacking.
Figure 2 shows the budget and, by implication, priorities for T/H research for FY,88-92. The close out of the current programs is also evident. Accident management and the INEL Technical Support Center will take a significant portion of the budget. The total budget will stay around $15 million. Dr. Shotkin has set up a priority list in the face of future budget cuts.
Cuts would be taken in the following order:
ROSA IV, Basic Studies, maintenance of TRAC-B and RAMONA, ICAp, Code Improvement, and the TSC synthesis report on natural circulation.
In response to Dr. Tien, Dr. Shotkin indicated that the proposed T/H budget cut (M25%) is an indication of the priority accorded T/H research at this time.
R. Jones comented on NRR's research user needs. He said the NRR/RES coordination is handled through the RRRG. NRR is in bacic agreement with the revised thrust and approach of RES. The proposed cuts appear reasonable under the circumstances. Mr. Ward asked if any needs are l
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MINUTES OF THE THERMAL HYDRAULIC NOVEMBER 18-19, 1987 SUBCOMMITTEE MEETING arising from advanced reactors. Mr. Jones said no specific T/H research needs have been seen at this time. Given the budget constrictions, NRR
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cannot justify expenditures for "paper planW at this time.
Mr. Ward was concerned that lack of research at the PDA stage for advanc.ed plants may cause problems later on. Mr. Jones said research may have to be ongoing with plant construction to confirm some design aspects of these new plants.
4.
R. Lee (RES) discussed the status of the MIST Program. As of September 1987, all Phase III MIST tests have been completed.
In addition, Toledo Edison ran three tests to support installation of a high point vent between the vessel upper plenum and the candy cane.
Mr. Lee discussed the results of the MIST tests vis-a-vis T/H issues of concern.
For the concern of primary depressurization, the results showed that the system always depressurized and fluid mass equilibrium was maintained. Dr. Catton asked if any MIST test was run to confirm the Davis-Besse analyses that the core would uncover during the "bleed" portion of feed and bleed. Mr. Lee said he was not aware of any such test; however, it was noted that the MIST facility mocks up a lowered loop B&W plant while Davis-Besse is a raised loop plant.
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Comparing the results of the 10 cm and'50 cm small break LOCA tests, Mr. Lee noted that for both tests, the RCS eventually makes its way to a similar leak flow rate (Fig. 3).
Mr. Ebersole expressed concern that the automatic depressurization of the OTSGs will deprive you of the use of the steam driven AFW pumps.
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MINUTES OF THE THERMAL HYDRAULIC NOVEMP;ER 18-19, 1987 SUBCOMMITTEE MEETING Results noted for other tests include:
Feed and Bleed - The loop fluid saturated and voided when the PORY was opened manually and primary system depressurization occurred; depressurization was augmented by surge line uncovery Steam Generator Tube Pupture - Loop conditions were highly asymmet-ric. The primary system depressurized by heat transfer to the affected SG. The intact SG became a heat source. After isolation of the affected SG, the primary system and the affected SG repres-surized.
Noncondensible Gas (NCG) Effe.cs - Venting of the high point vents to remove NCG promoted refill.
Dr. Catton recommended that RES assure that they do not leave the TRAC Code perranently "tuned" to MIST parameters; i.e., the code must be checked to assure it can properly scale up to the full size plant.
Figure 4 lists *.he RELAP-5 and TRAC code post-test calculations. Dr.
Catton noted a significant error in the TRAC Code predictions. He strongly recomerded that RES reevaluate this result to assure the code is not in error.
Further discussion brought out the fact that the cause of the error may not be well understood.
The B&WOG Analysis Comittee has requested B&W to examine this MIST test observations with respect to their applicability to B&W plants. B&W
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will complete the review and put together recommendations for B&WOG's consideration by end of Decerrber 1987. The B&WOG Analysis Comittee is scheduled to meet at the beginning of 1988 for resolution of this task, i
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MINUTES OF THE THERMAL HYDRAULIC 9-NOVEMBER 18-19, 1987 SUBC MlITTEE MEETING Figures 5-8 detail the status of the UMCP and sri-II programs. REC is nepotiating with EPRI for additional countr.rpart tests that NRC feels is needed to assure an effective counterpart analysis of the T/H phenornena.
Dr. Catton suggested a counterpart test (s) between UPTF and MIST, as UPTF has full-scale core vont valves. Dr. Shotkin said he would look into this and thet it appears to be a good idea. Dr. Catton also recomended that the MIST calculations should be directed to the CSAU program.
The coordination report on the MIST and counterpart (SRI-II, UNCP, ANL, etc.) experimer.ts will be updated in early 1988. The update will address the following issues:
An update of design information on integral and separate effects experiments.
A sumary of key results (obtained to date) that address the follow-ing issues decay heat renoval by single and two-phase natural circulation i
consequence of interruption of natural circulation decay heat removal by boiler-ce ser mode long-term cooling by means of 4 21 circulation or otherwise(e.g.,feedandbleed) consequence (s)ofsteamgeneratortuberupture consequence (s)ofloop-to-loopescillation A sumary of key results (obtained to date) that address MIST atypicalities.
A sumary of key results from post-test analyses.
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0 MINUTES OF THE THERMAL HYDRAULIC NOVEMBER 18-19, 1987 SUBCOMMITTEE MEETING Details of the MIST Phase IV Test Prorram are given on Figurc 9.
4 Mr. Ward expressed concern that the B&WOG may be tuning their version of RELAP-5 to the MIST test results.
Further discussion noted that RES will not make changes to the codes absent careful evaluation. There is no "B&W versicn" of TRAC.
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5.
The status of the OTSG SE test program was given by Mr. Lee. The objectives and current status are given on Figure 10. The AFW near-term activitics are shown on Figure 11.
Figure 12 lists the details of the OTSG visual AFW tests conducted at INEL.
Results of these tests will be reviewed for revision of the RELAP-5 B&W Cnde.
D. 9 lberg described the work of the INEL TSC (Technical Support Cen-6.
0 ter). A manager's meeting was held on Aucust 5-6, 1987, to discuss the scope and operation of the TSC.
Key results of the meeting included:
Name change to more correctly define function (from Technical IntearationCentertoTechnicalSupportCenter)
Reaffimed TSC role and objectives defined in NRC T/H integration plan (NUREG-1244)
TSC progran should be istue oriented and issues should be classified as short tenn (priority) or long term.
Improved TSC structure.
Review and agreed upon resolution of ACRS contents (see below).
i Agreed to greater involvement of TSC in NRC discussions, particular-ly RRRG meetings.
TSC has been seen as doing a good job performing tasks as defined in NUREG-1244.
MINUTES OF THE THERMAL HYDRAULIC NOVEMBER 18-19, 1987 SUBCOMMITTEE MEETING The structure, role, and interactions of the TSC are illustrated on Figure 13. Dr. Mark cautioned that RES needs to assure it has close oversight of the personnel in the TSC.
It was noted that there are no full-time people in the TSC, e.i., the duties are divided among other tt:xs. Dr. Tien expressed reservations with this approach as did Dr.
Mark, given that $2.5 million/ year will be devoted to this program. Dr.
Catton said the Natioral Science Foundation requires a full-time person to be heading all its projects.
RES believes they have the ear of EG&G management so they can get done what needs to be done.
A review of the Objectives, FY 1987 Accomplishments, and FY 1988 Plans for the RES priority issues were detailed (Figures 14-19).
In the area of Regulatory Utilization, the TSC is developing synthesis reports of research results. A draft NUREG has been prepared on the topic of feed and bleed and a synthesis report on natural circulation is planned for FY 1988.
Conclusions of the feed and bleed study were presented (Fig. 20).
Subcommittee discussion brought out that the need exists for the ACRS to review the operator guidelines for such maneuvers as feed and bleed.
RES responded to ACRS comments on t?.e TSC. RES agreed with our coment to review and assess TSC function fter ~ 2 years of operation 7.
Y. Chen overviewed results of 'ne ROSA-IV program conducted at the LSTF at JAERI. ROSA-IVmocksupaf4-loopPWR.
In response to Dr. Catton, Dr. Chen said test data has b: en slow in coring. RES has taken steps to j
assura more timely receipt o ~ test data.
Results of natural circulation and small break LOCA tests were dis-cussed. The natural circulsation tests showed core cooling could be maintained with RCS mass inventory down to 45% of nominal at 5% core power and down to 3% of nominal at 2% core power. The 5% hot leg small 1
HINUTES OF THE THERMAL HYORAVLIC
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NOVEMBER 18-19, 1987 SUBCOMMITTEE MEETING break LOCA tests resulted in a core heat-up as a result of depression of the core level due to interactions involving the CL Icop seal.
In all cases, the heat-up was terminated after the loop seal cleared.
This phenomena was also seen in Semiscale.
RES believes that the amount of level depression is proportional to the core power level. A complete report on the level depression results will be available in February 1988.
Station blackout tests were run ass'uming various equipment failures (no HPI,1-3 PORVs used, etc.) to address the issue of direct containment heating. The tests showed that even with all PORVs open RCS pressure never got to the accumulator setpoint, i.e., the operator must use HPI to cool the core.
SGTR test results were shown. Mr. Ebersole raised the issue of poten-tial recriticality due to dilution of borated water via the secondary.
RES said that studies have shown one needs to rupture M5 tubes before there is a problem here. Tbc SGTR tests showed that feeding and steam-ing of the intact SG was effective (eventually) in depressurizing the RCS.
RES and JAERI are proposing to extend their agreement for four more years (1988-1991). RES has requested that JAERI conduct the following tests.
Station blackout with a concurrent RCP seal failure.
Steam generator tube rupture with "arious recovery techniques.
Total loss of heat sink scenario with various recovery techniques.
Steam generator cooling.
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MINUTES OF THE THERMAL HYDRAULIC NOVEMBER 18-19, 1987 SUBCOMMITTEE MEETING Station blackout with depressurization techniques (DCH scenario).
Results from ROSA-IV small break LOCA tests are being applied to the CSAU rethodology for small break LOCA code calculations.
8.
D. Bessette (RES) described the code development and assessment program.
Final goals of the code programs include:
(1)useoftheCSAUmethod-ologytodemonstratetheabilityoftheTHcodes(TRACandRELAP-5);(2) use of-ICAP to support the CSAU effort; and (3) completion and release of the final code versions in June 1989. The ICAP agreements with j
various countries will be extended to a comon termination date sometime in 1991.
In response to Dr. Mark, Mr. Bessette said QA documents for the T/H codes have never been compiled before now.
Mr. Bessette noted that RES has developed a code improvement plan report. A "rough draft" was provided to the Subcommittee and RES solicited comments on the basic approaches stated in the document.
In j
response to Dr. Mark, Mr. Bessette said no future version of TRAC will be released until it can properly conserve momentum (RELAP-5 currently conserves momentum).
i Dr. Catton said RES should provide adequate justification before pro-ceeding with a new code version.
He indicated that serious fundamental problems remain with the numerics in TRAC and these problems should be addressedbeforeanewmodel(s)isdeveloped. He is not sure these serious problems are scheduled to be addressed, and he thinks develop-ment should stop until these issues are addressed.
Mr. Ward asked why development work isn't halted until the CSAU effort is complete. Mr. Bessette indicated that some code errors are known and by judgment one knows whether the errors are worth correcting.
Further discussion of code problems lead Dr. Tien to recomend that TRAC code developmer' be halted until the numerics is fixed.
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MINUTES OF THE THERMAL HYDRAULIC N0'v2MBER 18-19,1987 SUBCOMMITTEE MEETIN9 i
Mr. Lauben, in response to Mr. Ward, noted that TRAC development has essentially stopped since April 1987 in order to perfonn the large break LOCA CSAU, and the QA work. A TRAC code modification is being made in support of 2D/3D per RES's international agreement.
In response to Mr. Schrock, Mr. Lauben said the long-standing problem of flow regime modeling is being addressed by the CSAU effort.
CSAU is supposed to identify which code deficiencies need to be addressed.
Dr.
7uber indicated that the QA report will identify problems with the codes, and that over the last few years, development of code numerics has been a case of the "tail wagging the dog" vis-a-vis development of the physics.
Mr. Schrock said more expertise is needed in the area of understanding the fundamental physics of the problems seen with the codes. Dr. Zuber said CSAU will allow use of codes even with these errors, depending on the impact of a given error on the transient /
accident being modeled.
Further discussion ensued.
Dr. Zuber said that ICAP has given more objective assess;nent results than was obtained from the laboratories assessment efforts.
In response to Mr. Ward, Dr. Zuber said CSAU will be able to identify problems with the codes that impact analysis nf a given transient.
The current status and future plans of the code development program include:
TRAC-PF1/M001 Version 14.3, RELAP-5/ MOD 2 Cycle 36.06, and TRAC-BF1 have been frozen.
The codes are in the process of being documented (QA documents due 12/31/87).
Large break LOCA CSAU is in progress on TRAC (due 2/88).
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MINUTES OF THE THERMAL HYDRAULIC NOVEMBER 18-19, 1987 SUBCOMiiITTEE MEETING New procedures implemented for QA/QC in performing code configura-tion control.
TRAC Version 14.4 planned for release in June 88 for UPTF needs.
Changes are to be made in the following areas:
downcomer penetration entrainment/deentrainment in upper plenum condensation in hot leg and cold leg during ECC injection interfacial shear and heat transfer CCFL at the upper tie plate RELAP and TRAC have a number of deficiencies in common and a common approach will be followed in addressing these deficiencies.
TRAC-PF1/ MOD 2 and RELAP5/ MOD 3 versions scheduled for release in June 1989.
Mr. Ward noted that the BWR cude seems to be getting short shrift vis-a-vis the PWR codes. He asked if ICAP is addressing use of the "BF" version of TRAC. Mr. Bessette said NRC is getting full size plant data from BWRs in member countries.
At NRC behest, the ICAP participants have agreed, in principle, to formation of a Consortium to address code deficiencies in a coordinated, structured manner. A meeting is scheduled for December 15-16, 1987, to settle on a program of work. The Code Improvement Plan will serve as a focal point of effort. Peer review will be sought on the QA and Code Improvement documents.
MINUTES OF THE THERMAL HYDRAULIC NOVEMBER 18-19, 1987 SUBCOMMITTEE MEETING b
In response to Mr. Ward, RES said RELAP is more favored than TRAC by the' ICAP participarts. RELAP and INEL are seen as more "user friendly."
Discussing the ICAP consortium, Dr. Zuber noted that in the process of modifying a ecde, errors are introduced. He noted that only two ver-sions of TRAC have been developed tc maturity -- PD2 and PFI/ MODI, He said the last versions of TRAC and RELAP-5 will be mature in 1992 or so.
The CSAU exercise has convinced him that TPAC has some fundamental limitations that limit its capability for improvement. He said the current code versions are adequate for large break LOCA and he sees no reason to develop a MOD-3 and MOD-2 version of RELAP-5 and TRAC, respec-tively. Dr. Zuber believes RELAP-5 should become the working code for NRC use.
Dr. Tien said he agreed that the use of TRAC is limited and a new look is needed.
Dr. Zuber agreed and said a strategic-type tool is needed to address the problems of current concern (accident ranagement, op-erations,etc.).
Dr. Shotkin noted the following points vis-a-vis the Subcomnittee coments:
Traditional T/H issues will continue to arise and will need to be addressed.
RES will complete its work on its T/H tools (codes) by June 1989.
Agency' wide needs and users will dictate some of the T/H work, such as putting TRAC and RELAP on "PC" size computers.
i Overseas comitments will force improvenants to TRAC for the 2D/3D program.
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MINUTES OF THE THERMAL HYDRAULIC NOVEMBER 18-19, 1987 SUBCOMMITTEE MEETING Expertise must be maintained at the laboratories; RES can no longer make code changes without examining the impact of the change on overall reactor safety (i.e., does it make any difference?).
RES management is urging definitive completion of traditfor.31 T/H work.
i In response to Mr. Ward, Dr. Zuber said any problems found with TRAC via CSAU can be rectified. Dr. Tien said he tends to' agree with Dr. Zuber that the new MOD code versions won't be mature until 1901-92.
Dr. Tien said RES needs to set its priorities for the future vis-a-vis accident management. Mr. Bessette asked the Subcommittee for its advice on just what new (or improved) tools are needed in this area.
j Further discussion resulted in a suggestion from the consultants that it may be necessary to develop a separate code version for small break LOCAs and transients.
9.
G. Rhee detailed the status of the 20/30 program.
Key points noted
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include:
All testing is complete at the Japanese facilities (CCTF, SCTF).
Test results here have shown cross flows in the hori:ontal direction ef 7ectively mitigate local power density differences. A SO% power differenceyieldsabouta10%differenceinquenchfront(QF) elevations; QF in high power region trails that of the lower power region by about 10%. SCTF will be disassembled in June 1988. JAERI plans a new T/H test facility to study advanced reactor designs, inherent safety, etc. Dr. Schrock asked why the Japanese feel the need for advanced reactor studies and the U.S. does not. RES indicated that there is no real need for such research. Mr. Schrock indicated that this approach is repeating the mistakes of the past, l
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MINUTES OF THE THERMAL HYDRAULIC NOVEMBER 18-19, 1987 SUBCOMMITTEE MEETING For UPTF, 13 of 30 tests heve been run.
Test results noted includ-ed:
Fluid Mixing Test -- Cold ECC mixed well with the hot primary coolant in the cold legs; AT of about 160'C at the injection point reduced to AT of about 20'C at DC inlet for the injection rate of 10 Kg/sec.
Fot leg CCFL Test -- Steam / water countercurrent flow in a hot leg was stable under a typical PWR conditions. Thus, decay heat can be effectively removed during a small break LOCA through reflux condenser type of cooling.
ECC Core Bypass Test -- ECC delivery to the lower plenum was better than expected from small scale tests; 80% of irjected ECC delivered to the lower plenun as compared with 15% expected, based on small scale tests.
A UPTF follow-on test procram may be set up by extension of the agreenent to October 1990.
UPTF test data is being used to aid the TRAC-PF1/ MODI CSAU effort.'
- 10. The status of the work on continuing experimental capability (CEC) and an improved scale integral facility (ISIF) were noted.
In brief, the CEC /ISIF effort is being phased out as RES has indefinitely deferred work on a new integral T/H test facility.
RES will rereview the need for a new facility in about two years.
Mr. Ward urged RES to provide a synthesis r.eport on the issue of facili-ty scaling.
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MINUTES OF THE THERMAL HYDRAULIC NOVEMBER 18-19, 1987 SUBCOMMITTEE MEETING 11.
N. Zuber discussed the status of three separate effects (SE) research programs.
Key points:
Boron Mixing - study boron mixing in the lower plenum during an ATWS to address the stratification question. A test facility simulating a full-scale segment of a BWR LP was constructed at UCSB. Results to date show baron is entrained up to the core for natural circulation flows as low as 5% of rated ficw.
Dr. Catton suggested j
a test be run to demonstrate the boron is entrained from the bottom of the vessel to validate the above results.
Review Fuel Rod Thennal Analysis Methodologies - Work still in progress.
Water Hawer Due to Check Valve Failure - Investigate cold liquid fill rates to prevent water hamer in pipes with various orienta-tions. Testing is under way and results obtained to date indicate that water hamer occurrence is indeperdent of subcooling teepera-tures, i.e., it is controlled by the hydrodynamics of the situation.
The goal is to establish filling strategies (and rates) that prevent water hamer.
Dr. Tien expressed approval with this program.
- 12. The Subcomittee held an executive session. Mr. Ward indicated to RES that a full Comittee presentation would be timely at the February or March meeting.
The Chairman distributed a list of discussion items that were to act as a focal point for possible items in a draft report on'T/H research (Figs. 21-22).
Key highlights of the discussion of these items includ-ed:
Mr. Ward requested additional potential discussion topics beyond those on the subject list.
Dr. Catton recomended a topic on "the
MINUTES OF THE THERMAL HYDRAULIC NOVEMBER 18-19, 1987 SUBCOMMITTEE MEETING l
need for augmented data recording at nuclear plants." Dr. Tien suggested coments on RES's proposed change in approach (philosophy) for the role of T/H in plant safety. Mr. Ebersole suggested discus-sion of the rationale for feed and bleed, i.e., how well does plant process instrumentation relate to the actual T/H phenomena _seen during the feed and bleed process.
)
Need to understand the feed and bleed process - Dr. Catton indicated that use of MIST to test the feed and bleed phenomena and reduce uncertainties would seem prudent.
Need for process instrumentation to understand plant transient T/H phenomena - Suggest new look at process instrumentation needed to assure an operator can negotiate the EPGs.
Revision of DBAs to reflect current knowledge and experience -
Subcomittee agreed this is a good issue to bring forth for consid-eration.
Need for research to support advance reactors licensing - Mr.
Schrock suggested that NRC evaluate the proposed PDA designs to assure themselves no real problems exist. This work enuld aid in retention of code expertise.
Full-time manager for the TSC - No Subcommittee consensus was
)
evident.
i I
Counterpart tests in SRI-II and MIST vis-a-vis UPTF - Need to assure that redirecting UPTF tests to aid counterpart analyses is worth the trade-offs involved.
Status of future code development work - Drs. Catton and Tien suggested that there was no strong case to go on with new code
MINUTES OF THE THERMAL HYDRAULIC NOVEMBER 18-19, 1987 l.
SUBCOMMITTEE MEETING
'l versions of TRAC (M002) and RELAP (MOD 3).
Dr. Tien indicated that there is more important work to be done:
e.g., mock up advanced LWR designs with the existing codes.
i Dr. Tien said there is a new computer technology called CASE (com-puteraidedsoftwareengineering)thatseemstohnidpromisefor analysis of complex systems.
BWR vs. PWR research priority for code development work - Dr. Tien said GE had done a better job on basic research early on than the PWR vendors. This may explain the derth (need for?) of BWR T/H research.
Water hamer - Dr. Catton urged action here. he feels work is needed in the area of assessment of damage potential.
Heed to aucment process instrumentation at plants - Dr. Catton said data is needed to benchmark codes and simulators.
CEC need - I. Catton and V. Schrock said it was a mistake not to have T/H laboratory capability in the U.S.
The need exists for basic T/H research capability on an SE basis. A "captive" laboratory would be desirable.
- 13. The meeting was adjourned at 3:50 p.m.
- ++*
l NOTE:
Additional meeting details can be obtained from a transcript of this meeting available in the NRC Public Document Room,1717 H Street, N.W., Washington, D.C., or can be purchased from Heritage Reporting Corporation, 1220 L Street, N.W., Washington, D.C.
- 20555, (202) 628-4888.
k 1.
EGULATORY APPLICATIONS OF T/H ESEARCH A.
ISSUES AND EGULATORY IPPACT I.
GEERAL: PEVENT OR MINIMIZE REACTOR COE DAMAGE THROUGH UNDERSTAt0 LNG OF PLANT THERMAL-HYDRAULIC PERFORMANCE UNDER ACCIDENT CONDITIONS II. SECIFIC: (ECENT EXAPPLES)
ECCS RULE REVISION CODE SCALABILITY, APPLICABILITY AND UNCERTAINTY PRESSURIZED THERMAL SHOCK EGULATION 00WIBMATORY TESTS OF ECOVERY FROM SBLOCA, USING NATURAL CIRCULATION, FOR TMI-ELATED ISSUES IN B&W PLANTS ETHODOLOGY FOR B&W SAFETY E-EVALUATION ESPONSE OF B&W OTSG TO ACCIDENT CONDITIONS C0FFIRMATION OF EXTENT OF BORON STRATIFICATION DURING AN AlWS EVENT IN BWR's EXTENT OF SUPEREATED COEITIONS ON CONTAINENT EQUIPPENT INSTR 1 PENT TUE-LIE RUPTUE IN W PLANTS OPERATOR'S ABILITY TO DEPESSURIZE PLANT TO MINIMIZE EFFECTS OF DCH C[RNOBYL IPPLICATIONS ON REGULATORY EQUIREENTS FOR EACTIVITY ACCIDENTS AUDIT OF INDUSTRY SUBMITTALS (UPI)
ANALYSIS OF LWR SPERATING EVENTS (GIttiA, DAVIS-BESSE, TMI-2, ETC.) TO AID STAFF INVESTIGATIONS OF TESE EVENTS WATER HAFTER HAEB00K FOR EGIONAL INSECTORS S
?
FIVE-YEAR PLAN FY (M$)
PP0 GRAM AREA 88 89 90 91 92 WSEARCH E8W TESTING (MIST + OTSG) 2.3 3.9 1.0 0.5 0
2D/3D 2.9 1.3 1.0 0.2 0
ROSA-IV 0.7 0.6 0.5 0.5 0.2 BASIC STUDIES 1.0 1.0 1.0 1.0 1.0 ICAP 1.3 1.3 1.2 1.0 0.8 CODE IPPROVEPENT 2.5 2.2 2.0 2.0 2.0 00DE UNCERTAINTY 0.7 0.7 0.7 0.5 0.5 TOTAL 11.4 11.0 7.4 5.7 4.5 APPLICATIONS TECH SUPPORT CENIER 1.5 2.4 2.5 2.5 2.5 CONTAltfENT/ BOP 0.2 0.4 0.5 0.5 0.5 GERN0BYL IPPLICATIONS (REACTIVITY ACCIDENTS) 0.3 0
0 0
0 If00STRY AUDITS 0.2 0.5 0.5 0.5 0.5 EGULATORY ISSUES 0.2 0.5 0.5 0.5 0.5 ACCIDENT MANAGEPENT 0.2 0.8 1.0 1.0 1.0 ItJCLEAR PLANT ANALYZER (TTC 8 EGIONAL) 0.8 1.0 1.0 1.0 1.0 ftJCLEAR PLANT DATA BANK 0.5 0.5 0.5 0.5 0.5 ANALYSIS OF LWR TRANSIENTS 0.3 0.3 0.3 0.3 0.3 TOTAL 4.2 6.4 6.8 6.8 6.8 (RESEARCH & APPLICATIONS)
TOTAL 15.6 17.4 14.2 12.5 11.3 CONTINUING EXPERIPENTAL CAPABILI]Y 0.2 0
0.5 2.0 4.0 (ADVANCED LWR'S)
TOTAL 15.8 17.4 14.7 14.5 15.3 o
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13 A.
MIST PHASE-III RESULTS AND REPORT STATUS (CONTINUED)
(2)
POS~i TEST CALCULATIONS RELAP5:
ANALYSIS DRAFT REPORT 320503: COLD LEG DISCHARGE BREAK WITH LEAK ISOLATION COMPLETED ISSUED 340213: 1 SGTR, ONE LOOP C00LDOWN COMPLETED N0v. 1987 3801AA: CORE UNC0VERY IN PROGRESS JAN. 1988 3502CC: NON-CONDENSIBLE GASES COMPLETED Nov. 1987 320302: COLD LEG SUCTION BREAK COMPLETED N0v. 1987 TRAC:
3109AA: COLD LEG DISCHARGE (10 CM**2) BREAK COMPLETED N0v. 1987 320201: COLD LEG DISCHARGE (50 CM**2) BREAK COMPLETED NOV. 1987 3404AA: 10 SGTR, ISOLATED SG IN PROGRESS MAR. 1988 330302: FEED & BLEED, DELAYED HPI COMPLETED MAR. 1988 A
s k
s
15 C.
COUNTERPART PROGRAMS STATU_S UMCP 2x4 LOOP TESTS CONDUCTED:
5 SINGLE-PHASE NATURAL CIRCULATION TESTS 13 BOILER CONDENSER MODE TESTS 1 STEAM GENERATOR MAPPING TEST 5 HPI EFFECTS TESTS -
SCHEDULE:
APRIL-JUNE, 1987 INSTALLATION OF DAS AND ASSOCIATED SOFTWARE.
JULY-SEPT., 1987
- CONDUCT SINGLE-AND TWO-PHASE NATURAL CIRCULATION TESTS
- ADDITIONAL SBLOCA (NO AFW, NO HPI)
- PUMP CHARACTERIZATION TESTS (SINGLE-PHASE)
I t
OCT.-DEC., 1987
- HPl EFFECTS
- AUXILIARY FEEWATER EFFECTS
- FINISH PUMP' CHARACTERIZATION k
i.!!!
3 2:1
TEST COMPLETED AS OF NOVEMBER 1987 Test No.
Power Break size Sec. Level Initial Cond.
Comments BCM121886 140 KW 1/8 "
75 %
SYMMETRIC BCM121986 140 KW 1/8 "
75 %
SYMMETRIC BCM071587 141-30 KW 1/8" 50 %
SYMMETRIC Power Drop Test BCM071687 141-30 KW I/8" 50 %
SYMMETRIC Repeat of BCM071587 BCM073187 141 KW 1/8" 50 %
SYMMETRIC BCM091587 141 KW 1/8" 75 %
SYMMETRIC
- BCM091787 141 KW 1/8 "
50%
ASYMMETRIC BCM092287 141 KW 1/16 "
50 %
SYMMETRIC BCM092487 141 KW 1/16 "
50%
ASYMMETRIC BCM100687 141 KW 1/8 "
50 %
ASYMMETRIC Repeat of BCM091787 BCM100887 141 KW 1/8 "
75 %
SYMMETRIC Repeat of BCM091587
- BCM101387 141 KW 1/8 "
50 %
SYMMETRIC Repeat of BCM073187 BCM101587 141 KW 1/8" 75 %
ASYMMETRIC
- IIPIl02087 160 KW I/8-50 %
SYMMETRIC HPI on at loop saturation
- IIPil02287 152 KW 1/8 "
50 %
SYMMETRIC IIPI on at IRM HPIl10487 153 KW.
1/8 "
50 %
SYMMETRIC HPI on at loss of sink
- HPII10687 154 KW 1/8 "
50%
SYMMETRIC HPIon at BCM HPII10987 153 KW 1/8" 50 %
SYMMETRIC Repeat of HPI110487 ITLO31287 132 KW 1/8" 40 %
ASYMMETRIC Scoping test
- IILO31887 132 KW 1/8 "
40%
ASYMMETRIC Repeat ofITLO31287
- ITLO80587 168 KW 1/8" 50%
SYMMETRIC
- ITLO80787 168 KW 1/8" 50 %
SYMMETRIC Repeat ofITLO80587
- ITLO81487 168-80 KW 1/8" 50 %
SYMMETRIC Power drop test SNC072987 160 KW N/A 50 %
ASYMMETRIC Asymmetric to symmetric
- STPill187 141 KW 1/8" 50 %
SYMMETRIC Stepwise test: system frozen for three windows i.e., IRM, LOS, &
BCM NOTE:
- STANDARDTEST REPORT (STR), ** DATA TRANSFER REPORT (DTR)
ALL HPI AND STP TESTS WERE RUN WITHOUT PRESSURIZER m
l' 16 C.
COUNTERPART PROGRAMS STATUS (CONTINUED) l UMCP 2xf4 LOOP SCHEDULE (CONTINUED) l DEC.,1987-MAR.,1988 - INSTALLATION OF PUMPS
- STEAM GENERATOR INSTRUMENTATION FOR AFW
- RVVV MODIFICATION FROM MARCH, 1988
- SBLOCA WITH HPI/AFW
- PUMP BUMPS
- RVVV EFFECTS 4
.y
~
~
i 17 f
COUNTERPART PROGRAMS STATUS (CONTINUED)
I*iNFORD RESEARCH INSTITUTE 2 FACILITY TESTS CONDUCTED:
2 SINGLE-PilASE NATURAL CIRCULATION TESTS 3 TWO-PilASE NATUI'AL CIRCULATION TESTS 1 SMALL-BREAK LOCA 2 COUNTERPART MAPPING TEST ADDITIONAL TEST (S) MAY BE CONDUCTED AT THE BEGINNING OF CY 1988.
4 9
h.
~
i
'l 19 E.
PHASE-IV PROGRAM PLAN TO CONDUCT 8 ADDITIONAL TESTS:
2 (1) SBLOCA w/o HPI (ATOG C00LDOWN,10 CM CLI))
(2) SBLOCA w/o HPI (SNE AS (1), BlIT 30-35 MINS. INTO TIE TRANSIENT, INITIATE RAPID BLOWDOWN OF SG)
(3) CRYSTAL RIVER PLANT TRANSIENT G-16-81 COUNTERPART (11) RANCHO SECO PLANT TRMISIENT 12-26-85 COUNTEPPART (5) ADDITIONAL SCALING TRANSIENT PROPOSED BY BSWOG (6) STATIGN BLAC100T (80 GlYi TOTAL LEAK,1/2 CAPACITY AFW TO EDTH SGs) 2 (7)
INTERKDIATE SIZE BPEAK (100 0i CLD)
(8) SERIES OF SG SlEADY STATE TESTS (AFW SENSITIVITY STUDY) total CCST IS ESTIMATED AT $2 MILLION.
BR.WOG JOINED IN THE COOPERATIVE EFFORT IN FY 88.
IN FY 88, COST SHARE BETWEEN INDUSTRY AND NRC IS APPROXIMATELY 50-50 SPLIT.
4 1
i l
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e
N 1
OTSG PROGRAM PLAN AND STATUS CNCE THROUGH STEAM GENERATOR (OTSG) SEPARATE EFFECTS TESTING OBJECTIVES:
TO OBTAIN OTSG THERMAL llYDRAULIC DATA FOR TRANSIENTS THAT INITIATED FROM FULL POWER CONDITIONS.
TO ASSESS THE AFFECT OF AFW MODELLING ON PLANT TRANSIENT PREDICTIONS AND ADDI-TIONAL DATA NEEDS.
NRC/ INDUSTRY JOINT EFFORT NRC AND THE INDUSTRY REACHED AN AGREEMENT TO FORM A TECHNICAL ADVISORY GROUP (TAG) TO INVESTIGATE Tile TECHNICAL ISSUES AND DATA NEEDS TO FURTHER THE UNDER-STANDING OF THE OTSG BEHAVIOR UNDER TRANSIENT AND ACCIDENT CONDITIONS.
TAG WILL IDENTIFY DEFICIENCIES IN EXISTING OR PLANNED EXPERIMENTAL DATA BASE, AND RECOMMEND MEANS (INClLDING TESTING) TO RESOLVE THESE DEFICIENCIES.
TAG EFFORT IS SCHEDULED TO TERMINATE BY AUGUST, 1988.
,W
- N Btb
9 2-OTSG PROGRAM PLAN AND STATUS (CONTINUED)
NEAR TERM GTSG-AFW ACTIVITIES (FY 1988)
VISUAL AFW EXPERIMENT AT INEL:
TESTING WILL BE COMPLETED BY DECEMBER 1987.
AFW MODEL WILL BE DEVELOPED AND IMPLEt1ENTED IN RELAP5.
~
ASSESS RELAPS CODE AGAINST MIST, SAIC, OCONEE SG, AND TMI SG DATA.
ASSESSMENT OF THE AFFECT OF AFW MODELLING ON PLANT TRANSIENT PREDICTIONS.
CODES USED FOR ASSESSME';T:
TRAC-PF1/ MOD 1 AT LANL RELAPS AT INEL TRANSIENTS CONSIDERED:
STEAM LINE BREAK LOSS-0F-FEEDWATER PRIMARY OVERC00 LING SBLOCA 4
J I
Y VISUAL OTSG TEST AND ANALYSIS (A6855)
PURPOSE:
TO PROVIDE THERMAL-HYDRAULIC DATA 0F WETTING OF TUBE WALLS AND FLOODING AT TUBE SUPPORT PLATES BY AUXILIARY FEEDWATER (AFW) IN A B&W OTSG.
STATUS:
(A)
AIR-WATER SINGLE TUBE ADIASATIC (B)
STEAM-WATER SINGLE TUBE HEATED AIR-WATER MULTI-TUBE ADIABATIC (A)
AIR-WATER SINGLE TUBE ADIABATIC s
- EXPERIMENTS COMPLETED
- OBTAINED LOSS COEFFICIENT AND FLOODING CURVE (B)
STEAM-WATER SINGLE TUBE HEATED
- ONGOING
- PRIMARILY INFORMATION ON HEAT TRANSFER DATA AND HYDRAULIC (FALLING FILM - RIVULET TRANSITION FLOW RATES) WERE OBTAINED.
(C)
AIR-WATER MULTI-TUBE ADIABATIC
- 625 TUBES, 1/8 SECTOR OF AN OTSG, THREE TUBE SUPPORT PLATES.
- PRIMARILY INFORMATION ON AFW FLOW DISTRIBUTION (WITH AND WITHOUT D
UPWARD AIR FLOW), FLOODING CURVES, LOSS COEFFICIENTS WERE OBTAINED.
i
]O ALL EXPERIMENTS WILL BE COMPLETED BY DECEMBER, 1987.
k.
NRC
-RRPG
-MANAGEMENT REVIEW
-RES F C 1/n iESE RCH AT OTHER NR T/H TSC INSTITUTIONS OTHER LA8S REGULATDRY UTILIZATION PRIORITY ISSUE CLOSURE DISCIPLINES UNIVERSITIES o RESEARCH INTEGRATION o ECCS RULE
- HRA VENDORS o PLANT & TRANSIENT ANALYSES
- PRA o DATA EVALUATION & USE o ACCIDENT MANAGEMENT o LONG TERM COOLING AFTER A LOCA 0 SAFETY ISSUE CLOSURE OTHER DATA o CSAU SOURCES
- EPRI
- INTERNATIONAL
- OPERATING REACTOR 9
STRUCTURE, ROLE AND INTERACTIONS OF T/H TSC N
2w
1 ECC RlLE SlFFORT OBJECTIVE:
TO ASSIST NRC IN PREPARATION OF ECCS RULE SUPPORTING DOCUENTATION, ESPECIALLY TIE COWENDIUM FY 87 ACCOWLISifENTS:
0 ASSISTED NRC IN PREPARATION OF COWENDILM GRAPHICS SUPPORT CLERICALSUPkET FY 88 PLANS 0
INCORPORATE COPPENTS IN CONE!OllM 0
CLERICAL SUPPORT ON CONEf0IlM 0
Alff0 MATED EFERENCE RETRIEVAL A!0 SORT SYSTEM i
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1 LONG TERM COOLING OBJECTIVE:
DETERMIE SAFEIY SIGNIFICANCE, LIKELIHOOD AND CONSE0VENCE OF POSTULATED LOOP SEAL IN E STINGHOUSE PLANTS AFTER LBLOCA FY 87 ACCOM.1SifENTS:
0 DEP0NSTRATED CREDIBILITY OF POSTULATED SCENARIO FY 88 PLAN:
O PERFORM ENGIEERING ANALYSES USING SYSTEMS CODES Af0 SIPPLIFIED ANALYSES AS APPROPRIATE O
DOCIPENT ENGIEERING ANALYSES OF CONTROLLING IHENDENA AND PLANT RESPONSE e
P x
%~
a B&W SAFETY EVALUATION OBJECTIVES:
0 TO PROVIDE NRC WITH INDEPENDENT ASSESSENT CAPABILITY FOR B8W PLANT OIANGES 0
TO DEP0NSTRATE THE USE OF MJLTIDISCIPLINARY ltTHODS FOR ISSUE ESOLUTION FY 87 ACCOPPLISIPENTS 0
BASIC STUDY CDPFLETED 0
DRAFT SIUDY ESULTS PROVIDED TO NRC STAFF ON SCEDULE BY 5/1/87 0
DRAFT NUEG EPORTS SUBMITTED FOR EVIEW AND COPPENT FY 88 PLANS 0
ISSLE MJEG IN NOVEPBER/DECEPBER o
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i SHORT TEIN EVALUATION STUDIES OBJECTIVES: TO PROVIDE RAPID TURN AR00isD SCOPING EVALUATION OF SAFEIY ISSUES, E.G. BY (A) L11ERATUE EVIENS A.0 SUWARY (B) SIPPLIFIED ANALYSES (C) HISTORICAL DATA INSIGHTS FY 87 ACCOPPLISifENTS 0
SCOPING EVALUATION OF LONG TERM COOLING ISSUE O
SCOPING EVALUATION OF EACTOR VESSEL 7ENTING TO EDUCE DIECT CDNTAlffENT HEATING j
FY 88 PLANS i
0 SCOPING EVALUATION AS EEDED AM) AGREED UPON BY NRC e
._E,
S CSAU OBJECTIVE:_
ESTABLISl1 THE APPLICABILITY AND UN&RTAINTY ASSOCIATED WITH ELAPS AND TRAC-PWR ANALYSES OF SPECIFIED PLANT TRANSIENTS FY 87 ACCOPPLISWENTS:
O COPFLETED APPLICABILITY ASSESSENT OF ELAPS TO ANALYSIS OF LOSS OF FEEDWATER ACCIDENTS IN B&W PLANTS 0
PROVIED DRAFT NUEG FOR STAFF EVIEW AE COPPENT FY 88 PLANS 0
PUBLISH LOF APPLICABILITY EPORT 0
COWLETE AE PUBLISH ESULTS OF ELAPS APPLICABILITY TO SBLOCAS IN B8W PLANTS e
p 3
OVERALL CONCLUSIONS 0
FEED & BLEED IS VIABLE OPTION FOR DECAY EAT REMNAL IN PWRs WITHIN PLMff DESIGN LIMITS 0
PHYSICS OF FEED & BLEED EXPERIENTS AE ELL EPRESENTED BY TRAC AND ELAP, PROVIDING 00 E IDENCE IN APPLICATION OF CODES TO PLANT ANALYSES 0
TIE ELIABILITY OF OPERATOR ESPONSE TO IPPLEENT FEED AND BLEED HAVE NOT BEEN EVALUATED AND THIS COULD BE A MAJOR CONSIDERATION CCntilNG ATIUPTS TO INITIATE FEEDWATER RESULTANT CONTAMINATION / CLEANUP POSSIBILITIES I
f 4
i b
8,
,,). gi(S&rk /mWe A'n 11/19/87 DAW ltems that might be included in en ACRS letter making recommendetions on TH research:
1] Need forbetter understanding of the feed and bleed process. This is often tossed out as a generality, but what more specifically needs doing?. We might consider what Glenn Reed has proposed in his draf t letter.
I can see where there might be two specific subissues:
el Need to better understand how reliably PORYs will perform in the range of conditions during F&B. EPRI tests of s.ome years ago indicated there might be problems. There might be a particularly difficult challenge to those valves that are supposed to cycle open and closed, as in E plants.,
Even though there is no specific regulatory requirement for F&B and use of PORVs in this way, the process is being counted on to contribute to the j
safety performance of most PWRs.
- b} There might be e need to include in the MIST series tests which simulate opening the PORY without immediate supply of flow from HPl or MUP. This might be of particular importance for the Davis-Besse
' 0my$<8/7w /*?"hst'y /2cSyw dt,31 The DBAs now considered in the SAR could be updated experience of the last 25 yeers. There are two kinds of experience to be considered; il direct experience with transients and operating events that have actually occurred at plants,21 what has been learned about contributors to risk from PRA, SA studies, and other snelytical work.
This is applicable directly to only new LWRs, but there could be some eventuel benefit opposite new issues that might arise with existing plants.
f gl Another new raectorissue is whether existing codes and the existing body of experimental informellon era completely adequate for the eventual complete licensing and safety evaluation that will be required for future LWRs. Given that these LWRs, while not drastically difforent from the present generation, will have some changes. The NRC Staff does not seem to be taking this issue seriously, suggesting that present PDA applications are just for"peper reactors". I have concern that the vendors and future i
l epplicants era expecting more surety from the PDA process then this S
L
4
^
ettitude seems to indicate is going to be provided by the present review
- process, f,5) Should the TSCs be required to have e full-time manager for NRC responsibilities.
I Al is/should the originally planned SRI-Il and MIST counterpart test be completed?
/ J] Should there be e MIST counterpert test in the UPTF given the fact that I
the NRC had the foresight to have UPTF include RVVVs in the core barrel?
7 g) Should code development work continue with the ICAP effort to produce TRAC-PF/ MOD 2 and RELAP5/M003 by June 19897 Or will that really drog on.
to 19927 And should code development stop today; using RELAP5/ MOD 2 and ebendoning TRAC-PF to eng who went to continue to play with it?
Hos the decision point on diminshing returns been reached, passed, or is it being just now approached?
Is the planned code development work approprielag considering what might be learned from CSAU rather then just the pressures from more traditional code essessment activities liike ICAPl?
$ 7] Are BWRs getting enough attention in code development and essessment work? Are there really fewer TH problems with BWRs then with PWRs, or is there some accident of history operating?
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