ML19329D743
| ML19329D743 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 08/12/1976 |
| From: | Rodgers J FLORIDA POWER CORP. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| FOIA-80-250 NUDOCS 8003170684 | |
| Download: ML19329D743 (6) | |
Text
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. U.S. NUCLL AR REoubATORY AMIS 3 bon DoCKf:T NUMOE R l a. i>
50-302 NRC DISTRIBUTION ron PART 50 DOCKET MATERIAL TO:
FROM:
DATE OF DOCUMENT Florida Power Corp.
8/12/76 Mr. John F. Stolz S t. Petersburg, Fla.
DATE RECEIVED J. T. Rodgers 8/17/76
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DE SCTilPTION ENCLoSU RE Ltr. w/at'tached...re meeting on Tuesday (8/10/76)....concerning the dome repair process.
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. Note: Same Distribution as control # 8328.
PLANT NAME:
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Crystal River #3 SAFETY FOR ACTION /INFORMATION ENVTRO 8/20/76 RJL M ASSIGNED AD:
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tPROJECT MANAGER:
1 L. Engle PROJECT MANAGER!
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Hylton LIC. ASST.?
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N *Ji Power August 12, 1976 f-;M ; 'h g
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~I Mr. John F. Stolz, Chief
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Division of Proj ect Management hM U.S. Nuclear Regulatory Commission M
Washington, D.C.
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Florida Power Corporation
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W Crystal River Unit No. 3 N I'ds Containment Structure.
Dear Mr. Stol:
We appreciate the participation of you and your staff on Tuesday afternoon.
The questions and comments exhibited a continuing desire on their part to be actively involved in the dome repair process.
While we continue to pursue absolute answers through analyses, model runs and testing programs, it does become necessary from time to time to rely on experience and engineering judgement in decision making.
We advised you on Tuesday of our approach to such a point in
-the repair program as the completion of the delaminated cap removalr-Thirwork will-havrbeen ccmpTet~e~d s~o that visual inspection of the upper surface of the remaining concrete is possible over the whole area involved on Friday, August 20.
As I stated in my opening remarks (copy attac5ed) Tuesday on history and again in my conclusions, we at Florida Power Corporation will rely heavily on the results of such an in-spection in whether to continue the present repair ditgetion after next week.
We quote, "The removal of the cap allows for positive confirmation of surface acceptance of the lower concrete."
"The remaining item for a fina1' determination appears to require cap removal, i.e.,
visual appraisal by our engineers and consultants."
l saut General Office 3201 Tniny.tounn street soutn. P O. Box 14042. St Petersburg. Fonca 33735 813-866-5151
Mr. John F. Stol: August 12, 1976 Determination of-soundness of this surface is a critical point in our decision process and we feel that agreement after the inspection will provide us assurance of the "long term structural integrity of the containment" resulting from this 4
program.
51orida Power Corporation extends to you and staff an in-vitation to participate in such visual inspections with us or independently, so that you might'have the benefit of such direct experience and judgements which can be meaningfully expressed later.
You can make your arrangements through Atlanta Region II or direct with me, as you see fit.
We sincerely hope that you can arrange for such a site visit at this most opportune time in the repair program.
Ve1 truly yours,
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Rodger Asst. Vice President JTR/iw
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Mr. Norman Moseley I
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HISTORY Discovery - April 14,, 1976.
1.
Began analyzing reviews and theoretical approaches to possible causes while performing core borings to establish the extent of the laminations.
21 Initiated informal meetings with NRC staff for information exchange purposes.
3.
June 11 made interim report filing for repair calling for detensioning all dome tendons and anc~..> ring of upper cap to the lower structure.
This was followed by a June 18 meeting and receipt of questions on July 7.
4.
On July 24 Gilbert Associates approached FPC with results of their continuing analyses of the structure and the testing work going on at the site.
Their consultants had an opportunity to review this information and prepare their input to GAI on July 23.
5.
As a result of this exchange and a subsequent site meeting on July 29, FPC confirmed its acceptance of the course of action changes which you will hear about today.
A.
This is to stop detensioning activity with 18 tendons - 6 in each layer - symmetrical pattern -
detensioned fully.
B.
Using present dome surface as a work platform core drill 1" grout holes into the lower concrete.
C.
Remove upper cap to visually inspect upper surface of lower concrete and upper tendon conduit where exposed.
From our view, the new course is one which provides acceptable assurance of the long term structural integrity of the contain-ment.
The removal of the cap allows for positive confirmation of surface acceptance of the~10wer concrete.
It is prudent to take advantage of the opportunity afforded by the cap removal to enhance the str tural capability by the addition of a reinforced replacement cap.
It is not considered necessary to detension the existing dome to assure effective i
participation of the new cap in the final analysis.
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History - Page 2.
Finally, this change in course proposed to us based on sound engineering judgement substantiatea by a continuing field testing program offers to us a substantial potential for schedule time reduction.
You will hear more detail from Messrs. Moreadith and Pages rrow with time for questions at the end, as you require.
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P CONCLUSION If the lower concrete'is as good as present in forma tion
' indicates, then structural capability assurance is enhanced.
The-remaining item for a final determination appears to require cap removal, i e.,
visual appraisal by our engineers and con-sultants.
We now have a means of providino a replacement fully participating cap and thus a reconstituted 36" structure.
Numerical responses to analysis under present evaluations have j
been reduced to below criteria.
i Physical tests indicate acceptable responses of the structure.
i Grouting program is no longer a critical concern even though we do plan to carry out such a program, but we no longer have
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a any concern for main lamination or program effectiveness.
l Schedule comparisons indicate-the reconstructed cap approach gives us a more effective structure over life while providing j
a potential considerable saving in time.
The opportunity-j afforded to FPC by the present approach in our evaluation dic-i tated the change discussed and implemented.
i So we can better serve our purposes as they now appear to us, we-decided to remove (or not try to preserve) the cap.
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