ML19263E816
| ML19263E816 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 05/15/1979 |
| From: | Burwell S Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7906250319 | |
| Download: ML19263E816 (4) | |
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UNITED STATES 8
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NUCLEAR REGULATORY COMMISSION 5
j WASHINGTON, D. C. 20555 k.....,/
MAY 15 9 DOCKET NOS. 50-445 a.ND 50-446 APPLICANT:
TEXAS 9TILITIES GENERATINti COMPANY FACILITY:
COMANCHE PEAK STEAM ELECTRIC STATION, UNITS 1 & 2
SUBJECT:
SUMMARY
OF MARCH 2~7, 10': MEETING CN REPAIR OF REACTOR VESSEL SUPPORT PEDESTAL FOR COMAN NF. PEAK, UNIT 2 Summary A meeting was held with representatives of the Texas Utilities Generating Company on March 27, 1979 in Bethesda, Maryland.
The purpose of the meeting was to dis-cuss the repair procedures for relocating the misoriented vessel support pads on Comanche Peak Steam Electric Station, Unit 2.
The discussion was directed primarily at how the design of the repaired pedestal will differ from the original design of the reactor vessel support pedestal.
The applicant des-cribed the repair design for the load carrying members as structurally equiva-lent and physically similar to those on the original design on Unit 1.
A meeting attendance list is enclosed.
Background
The misorientation of the reactor vessel support structure at Comanche Peak, Unit 2 was described in our " Preliminary Notification of Event or Unusual Occur-rence" PN0-79-028, issued by the Office of Inspection and Enforcement on February 22, 1979.
The applicant reported that the reactor vessel support pede-stal was being constructed such that its mounting pads would not mate with the support pads on the reactor vessel.
The architect-engineer designed many features of the Unit 2 containment building, including the reactor vessel pede-stal, as a mirror image of Unit 1.
However, the nuclear steam system supplier did not design the primary coolant systems mirror image for this two unit station.
The reactor vessel supplied for Unit 2 is a duplicate of the reactor vessel installed in Unit 1.
As a result, the mounting pads on the Ur.it 2 pede-stal are misoriented arcund the reactor vessel's vertical axis by about 45 degrees. The applicant elected to modify the top of the pedestal to install the mounting pads in the prop'er orientations.
Construction had progressed to elevation 819 feet, several feet below the support pad, when the error was dis-covered.
I 2214 016 4
7906250.5/7
. MAY 1519'S Meeting Details The original design for the Unit 2 pedestal anticipated that the vessel would be supported on four pads which are approximately equally spaced around the periphery of the vessel.
The revised design shifts the location of each pad 45 degrees about the vertical axis of the reactor vessel. The reactor vessel support pedestal is a reinforced concrete structm which by design includes a greater density of reinforcing steel beneath the four vessel support pads.
Shifting the support pads 45 degrees therefore requires the installation of additional reinforcing steel under the new pad locations.
The applicant was strengthe.iing the pa:' locations by drilling 64 holes in the face of the pede-stal under each new pad location and grouting in #11 rebar. The holes are spaced on about 10 inch centers ano extend almost five feet into the pedestal.
Each new pad position also will have about 12 vertical #9 rebar installed in d similar fashion. The applicant states that the steel installed beneath the new pad position is equivalent to the initial design for this service, and that the new pads are designed to support the same loads as the pads on Unit 1.
The applicant advised that the modification of the Unit 2 pedestal required that the ventilation ducts to the reactor vessel supports be extended to the new support locations.
This did not cause any change in the ventilation systems performance, and was of no safety significance.
The applicant considers this repair of the Unit 2 reactor vessel support pede-stal a field design change, having no safety impact. The applicant further does not consider the repaired pedestal to be structurally different from the Unit 1 design and therefore does not plan to make separate structural load analyses for each unit.
No unresolved safety concerns associatea with the repair design for the Unit 2 pedestal were identified at the meeting, ifc NU c nix Sgottswood B Burwell Light Water Reactors Branch No. 2 Division of Project Management Enclosure :
Attendance List ccs w/ enclosure:
See next page 27!i 017
Texas Utilities Generating Company Ccs:
Nicholas S. Reynolds, Esq.
Debevoise & Liberean 1200 Seventeenth Street Washington, D.C.
20036 Spencer C. Relyea, Esq.
Worsham, Forsythe & Sampels 2001 Bryan Tower Dallas, Texas 75201 Mr. Homer C. Schmidt Project Manager - Nuclear Plants Texas Utilities Generating Company 2001 Bryan Tower Dallas, Texas 75201 Mr. H. R. Rock Gibbs and Hill, Inc.
393 Seventh Avenue New York, New York 10001 Mr. A. T. Parker Wes'inghouse Electric Corporation P.
s.
Box 355 Pittsburgh, Pennsylvania 15230 Mr. R. J. Gary Executive Vice President and General Manager Texas Utilities Generating Company 2001 Bryan Tower Dal'.as, Texas 75201
Enclosure MAY 151979 ATTENDANCE LIST COMMANCHE PEAK STEAM ELECTRIC STATION MARCH 27, 1979 NRC - STAFF S. B. Bur.: ell F. Rinaldi R. E. Shewmaker TEXAS UTILITIES GENERATING COMPANY H. C. Schmidt GIBBS & HILL H. R. Rock E. G. Gibson E. L. Bezkor Cherim Zion 2214 019