ML19220C026
| ML19220C026 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/27/1976 |
| From: | Silver H Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7904280081 | |
| Download: ML19220C026 (4) | |
Text
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UNITED STATES NUCLEAR R EGui.ATO RY cOMMis310N W ASHINGTON. D.
C.
20555 February 27, 1976 DOCKET NO:
50-320 APPLICANT:
Metropolitan Edison Ccmpany FACILITY:
Three Mile Island Unit 2
SUMMARY
OF MEETING OF TMI-2 OPEN ITEMS Representatives of the applicant and his contractors met with members of the NRC staff on February 19, 1976 to discuss various open items in the review. Principal items discussed are suntiarized below.
Containment Suma Testino The applicant had previously indicated his objecting to pe-famino an actual flow test using the sump (prototype test), and sugge;ted that model testing will be proposed to satisfy Regulatory Guide 1.79.
In support of this position, GPU, Burns & Roe.(B&R) and Alden Labs discussed design procedures for the sump and LPI pump suction piping and the pros and cons of prototype and model testing in general, and requested consid-eration of the principle of using valid model test;ng to satisfy the requirements of Regulatory Guide 1.79.
B&R noted tnat there is no sound analytical method to calculate vortexi~o.
They frequently model unusual pump installations to verify the empirical design but this was not done for TMI-2 since appropriate parameters such as submergence and velocities were considered quite conservative.
Negative factors included in 1easible prototype testing were presented:
1.
Difficulty of temporary installations.
2.
Minimal data at only a few conditions.
3.
No indication of incipient problems affecting margin of safety such - - i-surface vartexes, sensitivity to changes in sub-mer
, atc.
Advantage model testing sere asserted to be:
1.
Abilitt to vary all parameters to detemine most adverse conditions /
safety margins.
g5 3 790428063(
@ 2.
Ability te test fixes if tests indicate problems.
3.
Tests can be long t: m to assure equilibrium.
4.
More complete and accurate measurements and correlations can be made.
5.
Much better visual observation can be made.
Alden Labs discussed their experience and qualifications in this field, both in modelling for design purposes and for problem identification and correction. Results of moviel testing were asserted to be good.
Although the test has not yet been designed, it is expected that the model would be relatively large, with at least 6" diameter suction lines. Approximately 1/3 scale was suggested, producing flow and velocity ratios of about 1/10 and 1/1.732 respectively, with capability to vary flows in either direction by a factor of 2 The model would include the sump with outlet pipes, grids and gratings, sump room, ar.d nearby equipment and structures in containment. Transparent walls and piping would be used as appropriate, as would flow and pressure instrumentation.
The applicant was supported by B&R and Alden Labs in feeling that n 7 del testing can produce better results than the limited tests possible on the actual sump.
The need to demonstrate adequate pump HPSH, valve operability and system cleanliness, in addition to vortex control, was again emphasized to the applicant.
The NRC staff agreed to consider the appropriateness of model testina to demonstrate compliance, in whole or in part, with Regulatory Guide 1.79.
Containment Subcomoat tment Structures The applicant discussed his examination of the steam cenerator subcom-The partment wall for the effects of the peak pressure transients.
NRC staff agreed t'.a analysis appeared acceptable, but requested con-firmatory submittal of the following:
1.
sketches explanation of conservatisms in the original design-concrete strengt' 2.
rebar placement and amount, allowable stresses, etc 3.
description of the analytical approach and results P.
- 4.
safety factors.
Tyoe C Testino of Containment Isolation Valves After some discussion, the applicant agreed to modify table 6.2-15 as appropriate to list all isolation valves only, and to identify clearly the basis for exception from Type C testing for those isolation valves which it is proposed r.ot to Type C test. Table Q 03.14-1 and 2 will also be revised to indicate whethef or not the listed valves will te Type C tested.
Steam Line Break - 0 042.7 NRC concerns on this item were discussed briefly. Further discussion is apparently aecessary to assertain the reasons for lack of agreement between the staff and the applicant on several matters. This will be scheduled shortly.
Cartairment Purce Appropriate staff Containment Systems personnel were not present, but Accident Analysis Branch personnel indicated that for doce calculation the highest activity level permitted during purge will be used.
[ Subsequent t&lecons identified items required by CSB.]
Containment Soray Iodine Removal NRC personnel discussed results of recent thiosulphate tests which indicate et least 1% thiosulphate concentration will be required to assure prevention of release of the iodine after irradiation in an unfilterable fom. Since uniform drawdown of BWST and chemical tanks can be ?xpected to be a prcblem in a gravity system such as TMI-2, lean thiosulphate solution can be expected at least in some places in the containment.
Possible solutions to this problem werd discussed., including:
1.
use of metering pumps 2.
use of hydrazine instead of thiosulphate 3.
improving func'.ioning of the present system.
g 9
Harley Si fer, Project Manager Light Wa7et Reactors Branch d2 Division wf Project Management
Enclosure:
List of Attendees m
SS 243
LIST CF ATTENDEES NRC - MET ED MEETING FEBRUARY 19, 1976 NRC Harley Silver Brad Hardin S. Israel R. J. McDermott J. J. Walt Karl Kniel E. V. Imbro George Wrobei A. L. Gluckmann C. P. Tan D. Shum W. F. Paseday C. Ferrell Carl H. Berlinger GPU Max Nelson Lou Lanese Dick Heward Ed Wallace Dicr. Richards Alden Res. Lab Lawrence C. Neale
.