ML20127H380

Summary of 770824 & 25 Meeting W/Representatives of Mark I Owners Group in Bethesda,Maryland Re Results & Bases for Decision Point 2 in Mark I Owners LTP & Proposed Changes in Scope of LTP Due to Results of Decision Point 2

ML20127H380
Person / Time
Site:	Monticello
Issue date:	09/15/1977
From:	Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 9211180498
Download: ML20127H380 (11)

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,i e < UNITED STATES

!, f y t NUCLEAR RECULATORY COMMISSION

wASwiworoN. o. c. seses

's.,...../ SEP 151977 y DOCKETS NOS.: 50-219, 50-220, 50-237, 50-245, 50-249, 50-254, 50-259, 50-260aw 50-265, 50-271, 50-277, 50-278, 50-293, 50-296,'30-298, 50-321, 50-324, 50-325, 50-331, 50-333, 50-341, 50-354, 50-355, and 50-366.

LICENSEES: Boston Edison Company,-Carolina Power & Light Company.

Comonwealth Edison Company, Detroit Edison Company,  ! i Georgia Power Company, Iowa Electric Light & Power Com-pany, Jersey Central Power & Light Company, Nebraska Public Power District,. Niagara Mohawk Power Corporation.

Northeast Nuclear Energy Company, Northern States Power Company, Philadelphia Electric Company, Power Authority of the State of New York, Public Service Electric and Gas, Tennessee Valley Authority, Vermont Yankee Nuclear Power Corporation FACILITIES: Oyster Creek Nuclear Generating Station, Nine Mile Point Unit No.1, Pilgrim Unit No.1, Dresden Units Nos. 2 and

3. Millstone Unit No.1, Quad Cities Units Nos.1 and 2, Montical'o, Peach Bottom Units Nos. 2 and 3, Browns Ferry Units 'os. 1, 2 and 3, Vermont Yankee, Hatch Units Nos. 1 and 2, Brunswick Units Nos. 1 and 2, Duane Arnold Energy Center, Cooper, Fitzpatrick,.Encico Fermi Unit No. 2, and Hope Creek Units Nos. 1 and 2

SUMMARY

OF MEETINGS HELD ON AUGUST 24 AND 25, 1977 WITH-REPRESENTATIVES OF THE MARK I OWNER'S GROUP 4

On August 24 and 25, 1977, meetings were held in Bethesda, Maryland with representatives of the Mark I Owner's Group and the General Electric Com-pany (GE). The purpose of the meetings was to. discuss (1) the results and bases for Decision Point No. 2 in the Mark I Owner's Long Te'rm Pro-gram (LTP) (this Decision Point involved an assessment of the need to develop potential' load mitigating devices) -(2) proposed-changes in the scope or direction of-the LTP due to the results of Decision Point No. 2, and (3) the status of the analytical and testing programs being conducted as part of the LTP. Enclosures 1 and 2 are lists of the attendees of the August 24 and 25 meetings, respectively.

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Summary

> After introductory remarks by R. Logue, Chairman of the Mark I Owner's Group, R. Buchholz, GE, discussed the meeting agenda and provided an overview of the results of Decision Point No. 2. He emphasized that Decision Point No. 2 was a programatic decision for all facilities with the Mark I containment system. He further stated that the Mark I Owner's Group had concluded that a balance of load mitigation and structurcl modifications is optimum and that the optimum balance will vary from plant to plant. Enclosure 3 contains the slides used in Mr. Buchholz's presentation.

i B. Kohrs, GE, provided a more detailed discussion of the bases for the Decision Point No. 2 conclusions. Enclosure 4 contains the slides used in his presentation. He stated that the decision was based on (1) gen-eric programmatic efforts related to load definition and the establish-ment of structural acceptance criteria and (2) plant-unique cssessments of the costs of load mitigation and structural modifications. He indicated that the loads utilized for the purpose of making this assess-ment represented extensions of the STP loads, as updated by the ongoing testing program results. He further stated that the plant-unique assess-ments involved ratioing techniques (back to the STP baseline results),

rather than precise analytical analyses. He indicated that, as a result of Decision Point No. 2, the following areas of load mitigation will con-tinue to be investigated:

1. Safety-Relief Valve Line Mitigating Devices

2. Downcomer (LOCA/ Chugging) Mitigating Devices

3. Vent Header Impac'; Mitigating Devices

4. Drywell to Wetwell Differential Pressure Control

5. Reduced Downcomer Submergence He concluded by reemphasizing that a balance of load mitigation (SRV, LOCA/ Chugging) and structural modifications is optimum and that they do not yet know what mix of the two will be appropriate for particular facilities.

B. Kohrs, GE, then discussed Revision 2 to the Program Action Plan (PAP) which was submitted to the NRC on August 11, 1977. He stated that the PAP was revised (1) to reflect the program direction and new tasks which resulted from Decision Point No. 2, and (2) to provide a general program update which reflects modified tasks and/or task _ schedules. He stated that the PAP w?uld be next revised following the results of Decision Point No. 3 (October 1977) . Enclosure 5 contains the slides used in his

, presentation, which included a description of each of the specific changes in the PAP effected by Revision 2.

~3-B. Kohrs, GE, discussed ongoing activities which tate Decision Point No. 3 (this Decision Point i are designed to facili- }

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load mitigating devices for further testing nvolves and the selection of i

tion in Mark I BWR facilities). , ultimately, for installa- l i-He indicated that the selection of a downcomeinvolv l i

gation, and chugging load mitigation characteristi, cs. to identif vent header impact m was the goal of the Mark I Owner's Group He stated that it No.

load miti 3, a single downcomer configuration y, (i e at Decision Point FacilityFSTF). (gating device) for steam testing in the Full Scale Test steam testing in February 1973.He stated that the FSTF is sche of the downcomer design The foractivities testingc in leading the FSTF to thein selectioneady ld fo

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3. definition conduct of small of condensation scale pool swell oscillation mitigation loads testi 4 ng conduct of small scale chugging mitigation testing . ties conduct of small scale vent header impact mitigati p e on testing i design for testing in the FSTF, select a single thedowncomer additioit was renoted t it FSTF would have the effect of extending the LTPnal testing required t in th

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discharge device had demonstrated -

encher safety-relief valvepromisingHe st i

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device ber/ November would1977). be tested, in-plant at e Montic llresults and that such a o, later this year (Octo- LD

' Enclosure 6 contains the slides used in his p gr resentation. 6-i objectives of the FSTF programB. Smith, GE, provided ts.  ! a descrip for the FSTFtest matrix, the the status key features of of cons,truction the facility, the-ark'inI toFSTF, in presentat ion. program.

Enclosure 7 contains the slides used in his, and the int W. McCona

!ana-program, (ghy, GE, provided status reports on (1) the data 1/4 s

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L (3) the-1/12 scale 3-3 testing program 2) the flexible cyclinder ng programs, the ana

_ ticallmodel development program _

"ytical in his presentation. .

, and (4) the pool swell analy-tion tests" had been He indicated completedEnclosure-8 that andthe that 1/4 contains good scale'" scaling the slides-used e

valua-between the_ results of the agreement 1/12 scale

- scale testing programs.

had beenand obtained 1/4 slides i

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4 full report on the results of this phase of the 1/4 scale testing program will be submitted to the NRC in September 1977. He indicated that

" facility sensitivity tests" to evaluate the effect of facility stiffness on 1/4 scale test program results had been completed and that a report will be submitted to the NRC, He indicated that testing of 7 potential load mitigating devices in the 1/4 scale facility had been completed, with the following results:

a. all mitigators seem to mitigate upload

b. several mitigators produce significant reductions in peak vent impact pressure

c. devices mitigate some loads better than others

d. utilization of a 3 ft, submergence with full or partial AP is an effective mitigator

e. the " shroud" device appears to be the best mitigating device for pool swell A series of films of 1/4 scale tests using potential downcomer load mitigating devices were shown.

Mr. McConagny briefly described the status of the EPRI sponsored activities related to flexible cyclinder analysis. He stated that additional " drop tests" will be perfomed to determine the effect of internal pressure within the vent header at the time of pool swell impact. He stated that plastic defomation had been observed in tests without internal pressure in the cylinder at velocities of approximately 17 fps. A final report on this program is scheduled for submittal in December 1977. (The Mark I Owner's Group is also planning to perform flexible cylinder testing in the 1/4 scale test facility in December 1977).

Mr. McConaghy discussed the status of the EPRI sponsored 1/12 scale 3-D testing program. He stated that no " quick look" data has been issued at this time, but that a " quick look' report is anticipated in October 1977. He indicated that two new subtasks have been added to this pro-gram: (1) a feasibility study to determine submerged velocity in the supprescion pool photographically, and (2) conduct of asymmetric tests.

(He also noted that the Mark I Owner's Group have initiated a program to qualitatively assess comparative open tank pool swell hydrodynamic behavior between a cylinder and a 360 torus).

Mr. McConaghy discussed the status of the EPRI sponsored pool swell ana-lytical model development. He stated that 1/4 scale testing program data is being used to qualify the 2-D model. He further stated that, in the event that a downcomer load mitigating device is utilized, the analytical models would require modification.

B. Smith, GE, discussed the status of the LTP tasks related to the definition of steam condensation loads. Enclosure 9 contcins the slides

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l used in his presentation. He indicated that the analytical model develop-1 ment for predicting chugging loads on the torus shell (wall) was essentially complete. He further indicated that: (1) the current intention of the Mark I Owner's is _to rely on the empirical model, as qualified by the FSTF results, to arrive at LTP load definition, (2) the model will be used to develop sensitivity factors for use in plant-unique implementation of the' FSTF results, and (3) it is a strong possibility that the Mark I Owner's may elect to use a " bounding load" approach for chugging loads on the torus

shell. He also discussed the results of the recently-conducted Mark I i submergence chugging tests (single downcomer) at a foreign facility, the most significant of which is that dynamic pressure loads decreased with decreasing submergence. This program also included tests on a " teeth

and crown" downcomer mitigating device and demonstrated a 30% reduction in peak loads.

B. Smith also discussed the status of Mark I LTP chugging load mitigation testing efforts. He indicated that small-scale scoping (qualitative) tests had been performed on six mitigating device designs, which indicated that it was appropriate to perform further quantitative testing. Such quantita-l i tive testing is currently in progress and is scheduled for completion in September 1977.

M. Tanner, GE, discussed Mark I LTP activitios related to safety-relief valves. Enclosure 10 contains the slides u',ed _in his presentation. He indicated that the analytical model'develornent program for the ramshead device has been revised and that these revisions would be documented in October 1977 in a topical report which wou' d include a comparison of the model predictions with the Monticello in-p' ant test results. He pro-l vided a sumary of the Monticello test results and described the resolu-l tion of previously-identified discrepancies, i.e., torus pressure distribu-tion, leaking SRV/ hot pool conditions, and strain gage errors.

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M. Tanner also discussed the program for development and testing of an SRV load mitigating device (T-quencher device) including confirmatory in-plant testing in the Monticello facility and the development of an analytical model for such a device.

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A brief discussion sumarizing Decision Point No. 2 and the activities

' underway to arrive at Decision Point No. 3 was held with V. Stello and i D..G. Eisenhut. Subsequent discussions included (1) schedule for implementation of modifications / installation of mitigating devices, and (2) the potential for slips in the completion of the generic portion 4

of the LTP. These discussions highlighted the necessity for an early resolution of- the LTP_ structural acceptance criteria.

At the conclusion of the meeting, the NRC staff provided the following comments:

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' 1. A meeting should be scheduled in mid-September to discuss certain technical considerations which are of vital importance to Decision Point No. 3. i.e., the viability of drywell to wetwell differential pressure control and reduced submergence as LTP solutions, and NRC requirements related to the SRV/DBA pool swell load combination.

Such a meeting would also be an appropriate time to further discuss, in detail, the design features of the FSTF.

2. Activities related to the ertablishment of the LTP structural acceptance criteria should be accelerated to provide a meaningful input to Decision Point No. 3. The NRC St.lff requested a detailed schedule for the development of such criteria, narticularly as it effects Decision Point No. 3. within one week. The staff expressed i

2 its willingness to meet and work with the Mark I Owner's Group on this matter as often as is required to eccomplish this task.

3. The staff requested improvements in the timeliness of report sub-mitalls related to the various LTP tasks and requested an updated list of reports to be submitted, including the revised submittal dates.

4. The staff re-stated a previous request that each utility performing voluntary modifications to the corf.ainment system of its facility provide, for information purposes, to the NRC advance information related to such modifications. In addition, the staff identified a need for further discussions related to post-modification test requirements for modifications involving a breach in the contain-ment boundary.

5. The staff expressed their concerns regarding the activities related

- to investigation of hydrodynamic / structural interaction, i.e.,

that such activities may become a critical path item in the load definition process.

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%' staff requested that further interaction take place regarding the rir Licello SRV-mitigator test program before the conduct of testing.

.t was agreed that such interaction could take the form of a sub-nr: Pal describing the details of the test program or could be a t .nplished by means of another meeting on this subject. The staff identified two specific areas of concern related to this test program: (1) instrumentation to measure SRV pipe wall temperature rather than the temperature of the fluid in the SRV discharge line itself, anc (2) the lack of instrumentation to measure loads on the SRV piping in the drywell.

7. The staff identified the need for a separate meeting to discuss the Monticello Final Test Report (Ramshead device). Of particular

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. concern is the question as to how a " leaky valve" will be considered for SRV lord combinations.

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8. The staff stated that it would be reinvestigating torus temperature -

limits whether part of the Mark 1 program or not. (TheMark1 Owner's Group stated that this matter should be addressed to the individualutilities).

9. The staff requested that the Mark I Owner's Grou) submit 1/4 scale testing program information as it becomes availa>1e, rather than compiling it in one final report.

10. The staff requested that the September 1977 report on the 1/4 scale

" scaling studies" program include a discussion of the upward load impulse observed in the 1/4 scale tests (as compared to the impulse observed in the 1/12 scale tests).

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. S'u f L-John C. Guibert '

. Technical Assistant Division of Operating Reactors

Enclosures:

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Enclosure 1 ,

l MARK 1 OWNERS GROUP /NRC MEETING. AUGUST 24, 1977 ATTENDANCE LIST Name Organization J. C. Guibert NRC/ DOR C. 1. Grimes NRC/ DOR R. Stuart NRC/ DOR j A. A. Sonin MIT (for BNL)

J. Ranlet BNL G. Maise BNL K. Herring NRC/ DOR S. Hos ford NRC/00R K. A. Hoedeman NUTECH L. O. De1 George Com. Ed.

G. R. Edwards NUTECH M. A. Connor, Jr. Carolina Power & Light K. A. Meyer lowa Electric L. V. Sobon GE R. F. Reedy NUTECH R. N. Smart NUS Co.

R. P. Lovci N.P.P.D.

L. D. Steinert GE R. E. Rogers TVA B. W. Smith GE B. Kohrs GE R. H. Buchholz GE M. G. Mosier NMPC G. E. Wade GE R. B. Swenson PASNY B. Bauer PSE&G F. E. Gregor DECO H. 5. Yao NSC J. A. Iwolinski NRC/ DSS W. E. Cooper Teledyne J. R. Jordan GPCo T. T. Robin SCSI D. M. Crowe SCSI K. R. lyengar SCSI D. L. Whitt CBI W. R. Mikesell CBI L. Siegers NRC/RSR C. Anderson NRC/ DSS G. Bagchi NRC/00R

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. 4 Name Organization A. Hafiz NRC/SEB C. Hofmayer NRC/ DOR G. H. Neils NSP

, C. W. Sullivan EPRI W. J. McConaghy GE J. A. Kudrick NRC/ DSS G. Lainas NRC/ DSS R. H. Logue PEco G. E. O'Connor YAEC

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Enclosure 2 l l MARK I OWNERS /NRC

. I MEETING l AUGUST 25, 1977 4

ATTENDANCE LIST NAME ORGANIZATION J. Guibert NRC/ DOR C. 1. Grimes NRC/ DOR j A. A. Sonin MIT(ForBNL)

J. Ranlet BNL J K. Herring NRC/ DOR 4

S. Hosford NRC/ DOR C. Hofmayer NRC/ DOR L. Slegers NRC/RSR B. Kohrs GE J. Humphrey GE L. J. Sobon GE R. F. Reedy NUTECH R. N. Smart NUTECH K. A. Meyer Iowa Electric R. P. Lovci NPPD L. D. Steinert GE W. J. McConaghy GE R. E. Rogers TVA B. W. Smith GE R. H. Buchholz GE R. H. Logue PECo M. E. Tanner GE George Maise BNL G. H. Neils NSP K. A. Hoedeman NUTECH C. W. Sullivan EPRI G. R. Edwards NUTECH L. O. De1 George Com. Ed.

M. G. Mosi er NMPC R. B. Swenson PASNY

0. Mallon PASNY G. E. O'Connor YAEC H. S. Yao NSC W. F. Bauer PSE&G F. E. Gregor DECO W. E. Cooper TES G. E. Wade GE J. R. Jordan GPCo

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2 NAME ORGANIZATION T. T. Robin SCSI D. M. Crowe SCSI M. A. Connor Jr. CP&L D. L. Whitt CBI W. R. Mikesell CBI A. Hafiz NRC/SEB C. Anderson NRC/OSS J. Kudrick NRC/ DSS D. C. Jeng NRC/SEB R. J. Stuart NRC/ DOR

, L. C. Shao NRC/002 l

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