ML20235B750
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June 23, 1976 ACRS ACRS Technical Staff l
MEETING BETWEEN NRC STAFF AND FLORIDA POWER CORPORATION CONCERNING CONCRETE SEPARATION IN THE REACTOR BUILDING DOME 0F CRYSTAL RIVCR, UNIT-3 The above meeting between the NRC Staff and Florida Power Corporation (FPC) was held in Bethesda, Marylano on June 18, 1976. The purpose of the meeting was for FPC to discuss with the Staff their plan for re: siring the containment dome delamination at the Crystal River, Unit-3 project.(see Enclosure 1). The Staff-caucused before FPC met with them to consolidate some of the Staff concerns and formulate a position.
FPC was trying to obtain concurrence with their' repair plan from the Staff. The Staff, however, was not in a position to concur. The Staff's position is that they still have concerns over the repair procedures. The Staff has not had enough time to' review the repair plan in detail. The Staff will closely monitor the progress made during the repair. The Staff will only accept the.atructure when it meets its own FSAR acceptance criteria. The Staff stressed that all work is done at the Applicant's own risk (as always) and that the Staff would be careful not to accept any liability for the repair work.
The Staff had numerous questions and suggestions for FPC. On many issues FPC had to clarify points raised in the Reector Building Dome Delamination Repair Plan (Several extra copies of the Reactor Building Dome Delamination Repair Plan are available at'the ACRS Office). One of the concerns expressed by the Staff was in the detensioning sequence.
The Staff urged FPC to be sure the analysis of the forces created during the detensioning sequence was complete. There is concern that the i.oncrete may crack durir.g detensioning and further aggravate the problem.
The Staff is worried about PSAR force limits being exceeded on the dome during repairs.
The Staff favored the use of instrumentation placed in the concrete to monitor the integrity of the structure under the varying loads it will be subjected to during repair. FPC said instrumentation would be provided.
The Staff thought it would be a good idea to leave some instrumentation in nisce after the repair work was complete so that the status of the dome could be monitored throughout the plants' life.
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f The Staff was curious about how FPC could get grouting into some of the very small hair-line cracks which are present in addition to the major ( 2") dome delamination.
PPC assured the Staff that the grouting i
techniques could accomplish this.
The point was also made that the anchor bolts Which will be placed through the cap and into the dome.
would be the primary means of securing the deleminated cap. The grouting will prevent the anchor bolts from pulling the cap across the hollow delamination space when the anchor bolts are tightened.
The Staff also urged FPC to use original FSAR values where possible to ensure conservatism in analysis.
The value used for concrete compressive strength (fc) was changed from 5000 psi (PSAR value) to 6000 pai based on recent test data obtained from dome borings. The.
Staff was also concerned about FPC taking. credit for tendon conduit (Schedule 40 pipe, 5" diameter) as rebar. The Staff found that FPC was using two different values for the modulus of elasticity. One value is used for sustained loads and a higher value is used for short event loads.
Structural Engineering Branch made up a series of questions which may be asked of FPC. A saaple of some of these questions is attached as.
It is possible that in the future the Staff will send FPC a list of formal questions which will require written responses.
The Steff wishes to be kept informed by FPC of any development occurring at the site during the repair work. The Staff also wishes to be inforced as milestones are reached during the repair. schedule, such as, the start of detensioning, the start of drilling holes for anchor bolts, the start of retensioning, etc.
Presently, plans call for detensioning to start on June 23,1976, although this date is subject to additional slippage.
n/
Richard K. Major Assistant Engineer (Intern)
Enclosures:
As Stated i
File Guides:
1.
Crystal River 3, project 2.
ED - 14.2, Containment Structure Design 431' CRI - 1, Containment Structure, ACI Criteria ACRS er,.c.,
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