ML20054J038
| ML20054J038 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 05/27/1982 |
| From: | Zudans Z FRANKLIN INSTITUTE |
| To: | Okrent D CALIFORNIA, UNIV. OF, LOS ANGELES, CA, Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-CT-1458, NUDOCS 8206270100 | |
| Download: ML20054J038 (3) | |
Text
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4 00.Franklin Research Center A Division of The Franklin Institute Z.ZUDANS PH D.
Servor Vke Pressdent and Chief 0perating Oficer zo',e;$
May 27, 1982 c0 a
s Dr. David Okrent Energy & Kinetics Dept.
5532 Boelter Hall School of Engineering and Applied Science University of California Los Angeles, CA 90024 ACRS. Subcommittee Meeting on Midland 1 and 2, re:
May 20-21, 1982
Dear Dr. Okrent:
The two day meeting on Midland Units 1 and 2 from the overall point of view was'a satisfactory demonstration of the applicants management capability and determination to built a good quality plant.
Site visit confirmed the applicant's claim that there is no irrepairable damage done t'o DGB or any The other structures due to earlier nonuniform settlement of the soil.
proposed remedial actions appear to be extremely conservative, except for permanent dewatering system as discussed below.
Some specific comments on individual issues are as follows.
Although we did not have an opportunity to see the control room, the 1.
mockup of it and the discussion of the SPDS indicates that Midland will use the The color graphics of the plant status systems developed by B&W Owners Group.
will indicate plant operating range bounded by saturation and certain level sub-cooling lines (B&W Owners Group's design).
During site visit we examined the extent of cracks in DGB and service 2.
No confirmation of potentially serious cracking was water intake structures.
found and with the completion of the proposed underpinning, structures will be adequate.
From information presented during this meeting, there appears to be 3.
reason to believe that early problems identified with the QA/QC implementation The extent do not have broader implications on the quality of construction.
to which staff uses judgement in lieu of specific criteria in this matter is large and it might be of interest to the full Committee to learn how speci-fically did the Staff conclude that no broad, generic type of problems exist in QA implementation at the Midland Plant.
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70th A Race Streets. Philadelphia, Pa.19103 (215) 448-1000 TWX-710 6701889
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' May 27, 1982 I
Dr. David Okrent With respect to RCS high point vents, there is one on each of the 4.
There is two candy cane tops and one on the upper head of the pressurizer.
Applicant states that high point vent no high point vent in the RPV head.
in RPV head is not' necessary to assure natural circulation (demonstrated by an analysis).
The RPV vessel head volume is 14,000 cu ft.
Without RPV head vent and without water level measurement in the reactor (water level measure-ment exist on candy cane and on hot leg from hot leg outlet to top of candy cane, also core exit TC's exist) there is no way of knowing the status in the
.Argdments claiming ability to sweep out the vapor (or gas) from head head.
by " operational procedures" and natural circulation proof by analysis with I believe some direct indi-a bubble in the head ~are not convincing to me.
cation of state in RPV head should be required (HJTC or AP cells and RPV head vent).
Process steam supply system (terciary circuit - unique for Midland 5.
Plant) appears to be well planned and has little or no pot'ential impact on Midland transients.
Because of the revised SSE, engineering review of seismic margin in 6.
Criteria various safety related structures and components is in progress.
for this review are acceptable. Some of the analyses models appear to be rather primitive for the depth of detail conclusions reached by the analysts.
I believe Midland structures are adequate to support the In spite of that, added loads imposed by the upgraded SSE.
I am looking forward with interest to examine the fragility curves of structures and components to be used in the PRA study of the Midland plant.
Consumer Power Company management structure is good and staff posi-7.
tions are filled by personnel with significant experience in nuclear field.
See Item 3 above for In spite of that, problems in QA have been experienced.
further comment.
AFW system is the staff's pioneering effort to use reliability in 8.
The Staff provides reliability data base to applicants licensing decisions.
for AFW reliability ranking.
The reliability number (10-4) for AFW is l
used by staff not as a goal but as a trigger to make closer examination of This approach makes sense and might eventually lead to the the AFW system.
definition of probabilistic safety goals.
I Arguments leading to proposal for plant dewatering system appear to l
9.
be one. sided - increase of factor of safety against potential liquefaction threat l
in a couple'of sand pockets. Negative aspects (re: potential for undermining due to washout) appear to be discounted by the fine filtering of the pumped l
I am not sure whether the dewatering system will reduce or increase l
material.
l the plant risk since the proposed PRA does not appear to model it completely.
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3-May 27, 1982 Dr. David Okrent 10.
On p.ressurized thermal shock (PTS), SER indicacts for Unit 1 cir-from 20*F (initial) to 180*F cumferential beltline weld (WF 70) change of RTNDT af ter the first 4 calendar years of operation.
The Staff's conclusion (Page 5-25) that " Midland Unit 1 and 2 reactor vessels will not be jeopardized by thermal shock for at least 4 calendar years" is correct, however, the real question is what happens during the rest of the life of the RPV.
The rate of increase of RTNDT varies with time and plant and one would like to see projections as to how RTNDT will increase in Midland.
Since this is a new plant, it may be prudent to consider some of the steps evaluated for older plants for reduction of the fluence.
Very truly yours,
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nons Zudans Senior Vice President and ces Chief Operating Officer cc:
D.C. Fischer, ARCS G
S
.