ML20054J038

Comments on ACRS Subcommittee on Midland Units 1 & 2 820520-21 Meeting & Site Visit.Applicant Claim That No Irrepairable Damage Done to Diesel Generator Bldg Due to Earlier Nonuniform Settlement of Soil Confirmed

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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. 00.Franklin Research Center A Division of The Franklin Institute Z.ZUDANS PH D.

Servor Vke Pressdent and Chief 0perating Oficer May 27, 1982 zo',e;$

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s Dr. David Okrent Energy & Kinetics Dept.

5532 Boelter Hall School of Engineering and Applied Science University of California Los Angeles, CA 90024 .

re: ACRS. Subcommittee Meeting on Midland 1 and 2, 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 orThe any other structures due to earlier nonuniform settlement of the soil.

proposed remedial actions appear to be extremely Some conservative, except for specific comments on permanent dewatering system as discussed below.

individual issues are as follows.

1. Although we did not have an opportunity to see the control room, the mockup of it and the discussion of the SPDS indicates that Midland will use the systems developed by B&W Owners Group.

The color graphics of the plant status will indicate plant operating range bounded by saturation and certain level sub-cooling lines (B&W Owners Group's design).

2. During site visit we examined the extent of cracks in DGB and service water intake structures. No confirmation of potentially serious cracking was found and with the completion of the proposed underpinning, structures will be adequate.

3. From information presented during this meeting, there appears to be 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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8206270100 70th A Race Streets. Philadelphia, Pa.19103 (215) 448-1000 TWX-710 6701889 /[

1 I May 27, 1982 Dr. David Okrent

4. With respect to RCS high point vents, there is one on each of the two candy cane tops and one on the upper head of the pressurizer. There is no high point vent in the RPV head. Applicant states that high point vent in RPV head is not' necessary to assure natural circulation (demonstrated by Without RPV head an analysis). The RPV vessel head volume is 14,000 cu ft.

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 head. .Argdments claiming ability to sweep out the vapor (or gas) from head by " operational procedures" and natural circulation proof by analysis with a bubble in the head ~are not convincing to me. I believe some direct indi-cation of state in RPV head should be required (HJTC or AP cells and RPV head vent).

5. Process steam supply system (terciary circuit - unique for Midland Plant) appears to be well planned and has little or no pot'ential impact on Midland transients.

6. Because of the revised SSE, engineering review of seismic margin in various safety related structures and components is in progress. Criteria 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.

In spite of that, I believe Midland structures are adequate to support the 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.

7. Consumer Power Company management structure is good and staff posi-tions are filled by personnel with significant experience in nuclear field.

In spite of that, problems in QA have been experienced. See Item 3 above for further comment.

8. AFW system is the staff's pioneering effort to use reliability in licensing decisions. The Staff provides reliability data base to applicants l

for AFW reliability ranking. The reliability number (10-4) for AFW is used by staff not as a goal but as a trigger to make closer examination of the AFW system. This approach makes sense and might eventually lead to the definition of probabilistic safety goals.

I

9. Arguments leading to proposal for plant dewatering system appear to l 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 l due to washout) appear to be discounted by the fine filtering of the pumped material. I am not sure whether the dewatering system will reduce or increase l

l the plant risk since the proposed PRA does not appear to model it completely.

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• Dr. David Okrent -

3- May 27, 1982

10. On p.ressurized thermal shock (PTS), SER indicacts for Unit 1 cir-cumferential beltline weld (WF 70) change of RTNDT from 20*F (initial) to 180*F 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 Since this is a new plant, it may be to how RTNDT will increase in Midland.

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

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