ML20030B904
| ML20030B904 | |
| Person / Time | |
|---|---|
| Issue date: | 05/26/1981 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-1852, NUDOCS 8108250172 | |
| Download: ML20030B904 (9) | |
Text
{{#Wiki_filter:b MC/'5- /86~d ) 3 - DATE ISSUED: 5/26/81 t ki B,L Poe-8/ api t t MINUTES OF THE ACRS b b FLUID DYNAMICS SUBCOMMITTEE MEETING APRIL 28-29,1981 ~ SAN FRANCISCO, CA On April 28-29, 1981 the ACES Fluid Dynamics Subcommittee held a meeting in San Francisco, California. The purpose of the meeting was to: (1) review the status of the Mark II Containment Long Term Program; (2) discuss the status of USI A-2 " Asymmetric Blowdown Loads on PWR Primary Systems; and (3) discuss the application of aerospace technology to improve the reliability of valves used in nuclear plants. The principal attendees of the meeting are noted below: ~ Attendees /@ ACRS NRC ~/ ./ M. Plesset, Chairman C. Anderson y g\\@ 7 I3 J. Ebersole C. Economous - BNL (5 Q W. Mathis s D. Ward Mark II Owner's Group I,'[f gg A. Acosta, Consul tant S. Bush, Consultant !!. Chow I. Catton, Consul tant D. Roth T. Theofanous, Consultant G. Fitzsimmons Z. Zudans, Consultant R. Kingston P. Boehnert, ACRS Ltaff* R. Muzzy G. Ashley
- Dasignated Federal Employee J. Borhaug A. Bilanin Consolidated Controls Inc.
A. Sonin B. Bedrosian R. Reinicke J. Lehner H. Waller U. Simon - KWU D. Goebel - KWU J. Post f'108250172 810526 h2 PDR e
I-Fluid Dynanmics Mtg april 28-29,1981 Dr. Plesset, Subcommittee Chaiman, convened the meeting at 8:30 a.m. The Chairman explained the purpose and procedures for conducting the meeting, pointing out that Mr. Paul Boehnert was the Designated Federal Employee in attendance. Mr. C. Anderson (NRC) provided an overview of the NRC effort on the Mark 11 containment load definition issue. The lead plant program (LPP) is complete. The long-term program (LTP) is nearly complete. He said the LTP has concen-trated on the loads assocaited with steam blowdown and condensation and this would be the discussion topics for this meeting. These loads include i downcomer lateral loads and pressure and drag loads on the submerged containment boundary and components. The present areas that remain to be resobed for closing out the LTP are the definitions of the downcomer lateral loads and the uploads on the containment structural diaphgram. The Owner's Group-will also be submitting a report to the NRC redefining the chugging load for the LTP. NRC does not expect major problems in this area. The results of recent Mark II testing programs were described. These tests included: (1) the 4TC0 (temporary tall test tank-condensation oscillatbn) test program conducted at GE: (2) the CREARE multivent test program; (3) the JAERI (Japan Atomic Energy Research Institute) full-scale multivent tests; (4) the GKM-IIM tests conducted at KWU in Gemany; and (5) the GKSS tests also conducted in Germany. The 4TC0 tests simulate a full scale single vent and were used to confirm the condcasation-oscillation (CO) load definition developed for the LPP. The CREARE subscaled (1/10 - 5/12) multivent (1-19 vents) tests studied multivent effects on containment loads and show that single cell loads are bounding. The JAERI tests are 0 run in a full-scale 20 sector of a Mark II. Significant results to date from the JAERI tests show that C0 loads are lower than observed in 4TCO single-cell tests and that chugging is desynchronized between vents. Penn-sylvania Power and Light sponsored the GKM-IIM tests for use for their Sus-quehanna facility. GKM-IIM is a full-scale sincie "ent facility similar to the 4T facility. GKM-IIM tests had shown C0 and chugging loads in excess of tests run at 4T and this ler.d to the 4"C0 tests. The GKSS facility is a large-scale multivent (3) facility. Since some parameters are out-of-scale with the Mark II containment its results must be carefully applied.
Fluid Dynanmics Mtg .. 1 28-29, 1981 During the above discussions, Mr. Ebersole inquired whether the NRC had investittid the possibility that the loading on.the vacuum breakers may exceed obsign loads and result in disabling of the valves thereby breech-ing the suppression process. Mr. Anderson (NRC) said that JAERI had examined this area but he could not provide any details. He said ne would investigate this topic and report back to the Subcommittee. Mr. Kingston (GE) provided an overview of the C0 and chugging load definitions for the long term program. The C0 leads were developed basej on the 4TC0 tests. Two generic C0 loads were defined - a basic C0 load and a C0 load for combination with ADS activacion. The 4TC0 tests were characterized as conservative and the load definition was based on conservative selection of 4TCO data (peak amplitude time periods were used). The chugging loads are likewised based on 4TC0 tests. A set of seven key chugs which represented the severest chugging seen in 28 tests were used for the load definition. The chugging data base is fed into an accustic model to account for differences in pool response due to geometry differences between the 4TC0 facility and a Mark 11 facility. The load definition also accounts for desynchronization of the chugs. Chug desynchronization was confirmed by the JAERI full-scale multi-vent tests. Comparison of the chugging load definition with the JAERI tests has shown the load definition substantially bounds the envelope of the severe chugs. Dr. Zudans asked how the fatigue loads on the downcomers and SRV piping are defined. There was no clear response to the question, and HRC said th(y would follow up on this and provide the Subcommittee with the in~ormation in the near future. During a closed session (proprietary information) there was detaile'd discussion of the derivation of the load definitions for CO, chugging and downcomer lateral loads. The C0 load for the drywell is the 4TC0 drywell pressure histories applied uniformerly throughout the drywell. The suppression pool loading is spaced uniformerly over the pool boundary below the vent exit and is linearly attenuated to zero at the pool surface from the vent exit elevation (Figure 1).
Fluid Dynamics Mtg 1981 The chugging load derivation was detailed via a logic path (Figure 2). As noted above,the 4TC0 test data was used to develop the chug design loadings.- The JAERI full scale multivent data was used to confirm the desynchronization phenomena and provide comparison against the overall load definition. Both symmetric and asymmetric loadings are included in the model. The acoustic model used to develop the chugging loads was detailed. The model is semi-empirical since the chug source term uses the 4TC0 data. The model has been shown to bound the JAERI multivent data. The dynamic lateral load definition for the downcomers was discussed. There are two components of this lord definition: a single-vent dynamic forcing function developed from sit:gle vent 4T data and a multivent appli-cation method'which applies a multivent reduction factor to the above single-vent forcing function. The multivent load definition bounds the JAERI full-scale data. Mr. A. Sonin (BNL) outlined the problems NRC has with the Owner's Group definition of the single-vent lateral load. The Owner's Group postulated a " bounding load" based on 4T test results. The NRC believes the bounding load concept is questionable based on comparisons with the entire body of test data available and that the entire body of data is statistically in-adequate for a LOCA. NRC is requesting that the Owner's Group perfonn a statistical analysis of the available data in order to detennine which set or subset of data should be used to determine the final load definition and what should be the acceptable exceedance probability of the design load for a LOCA. Given the severity of the event, it was felt by the Sub-committee that faulted limits are appropriate. The NRC said they would take the Subcommittee comments under consideration. The Mark II Owners discussed the work proceeding on the definition of the diaphragm floor uploads and pool swell loads. For the disphragm loads, the Owners Group wants to specify a unifona load that will bound loads for all break sizes. This work is near completion and there doesn't appear to be any serious disagreement between NRC and the Owner's Group on these definitions.
Fluid Dynamics Mtg , 1981 Mr. C. Anderson summarized the effort on the Mark II program. He said the program is essentially finished. The remaining areas of effort in-volve the
- definition of the d7wncomer lateral load, the redefined chugg-F ing load, and submittal of the load definition for the containment struc-tural diaphragm. NRC will set a " drop-dead" date for submittal of the required infonnation by the Owner's Group (end of May). A draft NUREG closing out the LTP should be issued in July 1981.
NRC discussed resolution of USI Task A29-Safety Relief Valve Discharge Loads. Two main issues are of ccncern here: (1) suppres:;fon pool temperature limit, and (2) SRV air clearing loads for the Mark 11 con-0 tainment. For item (!), the current limit of 200 F will be modified (exceeded) for certain circumstances idepending on the depth of quencher submergence and steam mass flux rate). Test data from German (KWU) tests suggests some increase in the local temperature limit is appropriate. A draft NUREG on the pool temperature limit will be issued in July. Concerning the Mark II SRV loads, data from AWU tests have been used to develop a generic lead definition methodology that is less conservative than the requirements established for the LPP. The plants will have the option of using either of the load methodologies. A NUREG report on the SRV loads will be issued in September 1981. The details of the KWU Karlstein T-quencher tests and development of a generic load definition were presented. The KWU facility contained a full-scale prototype T-quencher in a pool volume representative of a Mark II " single cell". The test results indicated a large degree of conservatism in the LPP load definition. Accordingly, the Owner's Group developed a more realistic load definition based on the KWU data. NRC will issue a NUREG evaluating the new load definition in September 1981 as noted above. Mr. B. Bedrosian (Burns & Roe) discussed the development of an SRV load definition unique to the WNP-2 plant at Hanford Washington. WNP-2 differs from most Mark !! containments in that it is of steel construction. The load definition developed is based on SRV tests conducted at the Caorso
Fluid Dynamics Mtg iril 28-29, 1981 a (Italy) and Takai-2 (Japan) Mark 11 plants. These test showed that substantial conservatisms existed in the generic load definition proposed in the LPP. The new load tiefinition has been applied to the Caorso containment and has adequately predicted the loadings seen during these tests. Tne revised sup'aression pool temperature lini' for SRY discharge was described. The current limit (200 F local temperature) will be revised, based on KWU test data. The proposed limit would be plant unique and is based on the amount 2 of local subcooling available at given steam mass flux flows up to 100 LBh/ft -sec. (Figure 3). Dr. Economous (BNL) noted that LaSalle will be performing SRV tests to confirm the above proposed temperature limits. Mr. C. Anderson reviewed the status of USI A-2 Asymmetric LOCA Loads on PWR Primary Systems. NUREG-0609 has been issued which concludes the generic aspect of the. issue and provides the criteria for plant specific reviews. W has submitted a topical report that argues that one would see " leak before-break" and thus the double-ended guillotine break is not a viable concern. Mr. Anderson stated that the NRC has reviewed this W topica' and has accepted the W argument, A draft NUREG on this item should be issued in the second quarter of 1981. Dr. Plesset suggested that the ACRS examine this issue including the combining of LOCA and seismic loads. Mr. H. Walker and Mr. R. Reincke of Consolidated Controls Corporation provided a presentation on the application of aerospace technology to the design of values used in nuclear plants with the goal of increasing their reliability of safe operation. The focus of the presentation was to present a conceptual design for an improved PORV appling basic concepts of aerospace valve design. Such concepts include: (1) no sliding fits (use diaphragms or bellows), (2) redundant position sensors, (3) ability to test valve function, and (4) design 100% force margin into the valve to guarantee closure. The Subcommittee suggested that this presentation be made to the full Committee for their infonnation in the near future. The meeting was adjourned at 3:10 p.m. on April 29, 1981.
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