L-84-349, Forwards Response to IE Bulletin 84-03, Reactor Cavity Seal. Design of Facility Reactor Cavity Seal Ring Provides Double Seal Against Leakage.Gross Seal Failure Not Consideration at Facility
| ML20101C310 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 11/27/1984 |
| From: | Williams J FLORIDA POWER & LIGHT CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| IEB-84-03, IEB-84-3, L-84-349, NUDOCS 8412210033 | |
| Download: ML20101C310 (7) | |
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{{#Wiki_filter:"~~ P. O. BOX 14000, JUNO BEACH, FL 33408 ggrapo PEGloti '.I @ug ATi./WIA. GCORGI A g 84 NOV 30 P 1 : 53 rLoRioa rower a licht co PANv November 27, 1984 L-84-349 Mr. James P. O'Reilly Regional Administrator, Region 11 U. S. Nuclear Regulatory Commission 101 Marietto Street, N. W. Suite 2900 Atlanto, GA 30323
Dear Mr. O'Reilly:
Re: St. Lucie Unit No. I Docket No. S0-33S IE Bulletin 84-03 Reactor Cavity Seal Attached is Florida Power & Light Company's response to IE Bulletin 84-03 for St. Lucie Unit 1. Although the new St. Lucie Unit I seal has not yet been fabricated, it's design is identical to that used on St. Lucie Unit 2 during the post refueling outage. Very truly yours, .LN lik J. W. Williams, Jr. Group Vice President Nuclear Energy JWW/RJS/kgn Attachment kDRkhh3841127 05000335 G .PDR \\ I $6ll PEOPLE.. SERVING PEOPLE
4 STATE OF FLORit;A ) ) ss. COUNTY OF DADE ) J. W. Williams, Jr. being first duly sworn, deposes and says: That he is a Group Vice President of Florida Power & Light Company, the Licensee herein; That he has executed the foregoing document; that the statements made in this document are true and correct to the best of his knowledge, information, and belief, and that he' is authorized to execute the document on behalf of said Licensee. s J. W. Williams, Jr. L. Subscribed and sworn to before me this 32_ day of s-gg,19pr. A A. 2??Y s OTARY PUBLIC, in and for the County of Dade, State of Florida N0flGY NjBLIC ST4TE OF FLORIDA MY C04"ISSIC,h fyP. FfB M.IiS8 800ED TliRU CthERAt lei. cau. My Commission expires: /v//r
Re: St. Lucie Unit 1 Docket No. 50-335 IE Bulletin 84-03 ATTACHMENT ' cwrrr SmL RDU WAURTION 1 The reactor cavity is an annular gg between the reactor vessel flange, radius 9'- I" and the primary shield wall concrete, radius Il'-0". During refueling, a box section toroid, the cavity seal ring, inside diameter 18'-4", outside diameter 21'- 10" is placed in the reactor cavity leaving two - one inch wide annular slots with centerline diameters of 18'-3" and 21'-11". The cavity' seal ring rests on six 16 WF 36 beams imbedded in the primary shield wall at 60 intervals. Reactor cavity details are shown in Figure 1. The two enular slots are filled with specially designed wedge shaped inflatable seals, Seal Master type P-25, during refueling to assure that a positive water seal is maintained. The seal cross section is shown in Figure 2. The top of the seals are fastened at 10* Intervals to a one-inch thick seal plate which spans the entire cavity. The seals are attached to the seal plate by bolts that extend throogh the seal plate into a female threaded fitting ernbedded in the rubber seal. The seal plate bolts to the reactor vessel flange and an embedment ring on the primary shield wall stabilizing the seals and holding the entire assemh!y in place. The cavity seal ring, seals, and seal plate are attached through the lifting assembly to allow the entire assembly to be installed or removed with one lift. See Figure 3 for a sketch of the entire assembly. The design of the St. Lucie reactor cavity seal ring provides a double seal against i leakage. The primary seal is created by the seal plate forcing the wedge portion of each seal into the annular ggs. The inner seal wedges between the reactor vessel flange and the inner ring plate on the cavity seal ring. The outer seal l. wedges between the outer ring plate on the cavity seal ring and the embedment l ring on the primary shield wall. After the seals have been installed and the seal plate has been fastened in place and torqued, the seals are inflated. The balloon l. portion of the seals expands against the sides of each annular gap, to provide a l secondary seal for each gg. Because of the primary seal, loss of air to the seal will not result in water leakage around the seal nor contribute to failure of the sealing system. i FPL has analyzed the potential for gross seal failure as occurred at the Haddam l Neck Plant on August 21,1984, and has concluded that gross seal failure is not a credible event at St. Lucie. Testing was performed to determine the equivalent hydrostatic head required to force the seal through a mock-up reactor cavity. The results of the tests for the design configuration indicated that a hydrostatic head equivalent to 274 feet was required (assuming the worst case tolerance, i.e., largest gap, determined by as-built &awings) to cause the seal to fai'. Considering the actual hydrostatic head is 26 feet, the seal has a factor of safety greater than 10 for the design case. Further testing w/ worst case); a hydrostatic as performed with silicone lubricants and with the seals deflated (single failure head equivalent to 102 feet was required for seal failure. Even with this worse case / single failure condition, the factor of safety is approximately 4. b . - -.. - ~ - - - -
Attochment Page 2 The St. Lucie Unit 2 Reactor Cavity Seal, designed as described above, was used during the post refueling outoge and was completely leak tight. Based on the results of the testing, and the leak tightness of the St. Lucie Unit 2 seal demonstrated during the post outoge, gross seal failure is not a consideration of the St. Lucie Plant. The detailed calculations of. consequences as requested by the Bulletin have therefore, not been oddressed, t-l l
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