ML19260C467
| ML19260C467 | |
| Person / Time | |
|---|---|
| Issue date: | 12/01/1979 |
| From: | Bates A Advisory Committee on Reactor Safeguards |
| To: | Plesset M Advisory Committee on Reactor Safeguards |
| References | |
| REF-GTECI-A-07, REF-GTECI-CO, TASK-A-07, TASK-A-7, TASK-OR NUDOCS 8001030574 | |
| Download: ML19260C467 (3) | |
Text
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'o UNITED STATES c
! j*,,.. ( [',,g NUCLEAR REGULATORY COMMISSION
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s ADVISORY COMMITTEE ON REACTOR SAFEGUARDS
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WASHINGTON, D. C. 20555 O
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December 1, 1979 TO:
M. Plesset, 2
A. Bates g/ ;.
FROM:
SUBJECT:
ACRS FLUID DYNAMICS SUBCOMMITTEE MEETItG, NOVEMBER 16, 1979 I have prepared the attached proposed meeting sumary for your review.
Copies are being distributed to the other ACRS members and Subcommittee consultants for their infc,rmatin and comment. Corrections and additions will be included in the minutes of the meeting.
Attachment:
as stated cc: ACRS Members ACRS Technical Staff I. Catton Z. Zudans V. Schrock S. Bush C. Grimes S. Hanauer R. Baer 1700 180 k
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December 1, 1979 PROPOSED
SUMMARY
OF THE NOVEMBER 16, 1979 FLUID DYNAMICS SUBCOMMITTEE MEETItG
Purpose:
The purpose of the meeting was to review a number of issues related to the Generic Long-Term Program on Mark I Containments.
Attendees:
ACRS members in attendance included:
M. Plesset and H. Etherington. Consultants included I. Catton, Z. Zudans, S. Bush, V. Schrock.
Meating Highlights, Agreements, and Requests 1.
Mr. C. Grimes, NRC Staff, reported that the NRC Acceptance Criteria for the Iong-Term Program were transmitted to the owners on October 31, 1979. We Staff is now in the process of preparing a Safety Evaluation Report which will be issued in December 1979. He indicated that the meeting would con-centrate on the key areas of disagreement between the Staff and Owners.
2.
Mr. V. Tashjian, G.E., reviewed the Owners basis for the upward pool swell loads. W e loads are based upon 2-dimensional tests at 1/12 and 1/4 scale and 3-dimensional tests at 1/12 scale. %ese tests indicate that the 2-D loads are conservative with respect to the 3-D loads.
Based upon 3D/2D tets at 1/5 scale at LLL the NRC is requiring a 21.5%
margin on the 2-D based upward loads. We owners reviewed several items in the LLL tests that they believe, if properly accounted for, do not lead to higher 3-D loads. W e owners do not believe the additional NRC margin is necessary.
3.
Dr. S. Bush indicated that he had some concern with regard to long-term low or medium cycle fatigue loads due to repeated thermal stresses in local areas from SRV discharges. Considerations should be given to imposition of LOCA loads upon degraded or fatigued torus boundries and appropriate inservice inspection programs.
4.
% e NRC indicated that they arev requiring the Mark I owners to use the vent orifice test data rather than the split orifice tests for determining the ring header sweep time. % is produces a flatter pool swell around the torus and consequently is a more conservative load definition.
5.
W e Mark I plants will be installing a deflector below the vent header to deflect the water and loads away from the vent header. We loads on the deflector are based upon impact and drag loads. %e NRC Staff is requiring a revised drag coefficient which is in line with prior work in the literature. 21s has the effect of increasing the drag force 1700 181
Fluid Dynamics Mtg Summary 11/16/79 December 1, 1979 by a factor of 3; however, the NRC believes that the free field fluid velocities used by the Owners are too large and that if appropriate fluid velocities in the region of the deflector are used the loads will not charge significantly. The Owners indicated that they are developing an improved methodology for calculating the water velocity at the deflector and will be sutmitting revised velocities to the NRC.
6.
He Owners Group described the tests conducted in the Full Scale Test Facility, the fluid structure interactions observed and the derivation of the load specification. The tests covered a range of break sizes for steam and saturated liquid breaks. Only one test was run at high mass flux levels simulating a large liquid line break. Condensation oscilla-tions produce the significant loads on the torus and downcomer structures, chugging produces loads that are consdierably lower than the condensation oscillations. We NRC has accepted the load definition for condensation oscillations, however since there is only data available from one high mass flux test (which produced the highest loads) the NRC is requesting at least two additional tests at high mass flux rates to determine and verify that the earlier tests produced typical results. W e Mark I Owners are strongly resistant to these additional tests, they do not believe they are necessary, they will take 9-12 months to complete and they pose the potential for having to make additional nodifications to the torus beyond those changes scheduled to be carried out prior to December 1980. W e Owners object to being in a position of making engineering and structural changes involving several million dollars per plant during 1980 with a potential of additional NRC requirements following the new tests.
We NRC indicated that they do not expect to see significantly different loads with the additional tests but believe that some additional confirma-tion is necessary since only one test was run under conditions which pro-duced the highest loads.
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