ML20106D459
| ML20106D459 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 09/26/1984 |
| From: | Tucker H DUKE POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| IEB-84-03, IEB-84-3, NUDOCS 8410250164 | |
| Download: ML20106D459 (4) | |
Text
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DUKE POWER GOMPANY
[g P.O. BOX 33189 CHARLOTTE, N.C. 28242
'HAL B. TUCKER TELEPitONE T303PREmmE=v (704) 373-4531 84 DCT 5 P3: Rtember 26, 1984
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-n-James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory. Commission Region II 101 Marietta Street, NW, Suite 2900
-Atlanta, Georgia _30323 R'e : Oconee Nuclear Station Dockat Nos. 50-269, -270 -287 IE Bulletin 84-03
Dear Sir:
In response to IE Bulletin 84-03 dated August 24, 1984 concerning recent failure of refueling cavity water. seal and rapid draining of the refueling
. cavity at the Haddam Neck Plant, please find attached a report for Oconee
. Nuclear Station pursuant to Action Item 2 of the bulletin.
I declara under penalty of perjury that the information contained herein is correct to the best of my knowledge as executed on September 26, 1984.
Very truly yours,
,/
a 4T Hal B. Tucker MAH:slb-
' Attachment cc: Document Control Desk U. S. Nuclear Regulatory Commission
_ Washington, D. C.
20555 Mr. J. C. Bryant NRC Resident Inspector 0conee_ Nuclear Station
,Ms. Heler. Nicolaras s
~ 0ffice of Nuclear Reactor Regulation-U. S. Nuclear Regulatory Commission Washington, D. C.
20555 8410250164 840926 PDR ADOCK 05000269 0
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- '7 g7 DUKE POWER COMPANY OCONEE NUCLEAR STATION
Response
to IE Bulletin 84-03 Action ~ Item 2 Evaluate the potential for and consequences of a refueling cavity water seal failure and provide a summary report of these actions.
Such evaluations should include consideration of: gross seal failure; maximum leak rate due to failure of active componenets such as inflated seals;' makeup capacity; time to cladding damage without operator action; potential effect on stored fuel and fuel in transfer; and emergency operating _ procedures.
' Response 2 Considering the difference in. seal plate and gasket configuration between that at;0conee'(Fig. 1) and that described in IEB 84-03, a gross seal failure of the magnitude experienced at Haddam Neck is not a credible event at Oconee. Correct alignment of.the seal plate is assured by 4 alignment studs and'72 threaded studs. Water pressure above the scal
-plate, gasket sealant, the 1/8 inch recessed edges, and a final torque value of 150 ft.-lb. per nut ensure gasket stability.
A leak' rate of less'than 50 gpm would be expected from the Refueling Canal-even in the unlikely event of a totally dislodged inner seal.
Instrumentation and procedures currently in place to detect and respond to unexplained water loss in the Spent Fuel Pool and Refueling Canal would ensure that 50 gpm leak rate would be detected and mitigated.
Additional information is as follows:
- 1) A leak rate of 50 gpm translates'into a time span of approximately
-71 hours before a. fuel assembly located in the Fuel HandlingLBridge
-Mast would become uncovered assuming no operator action.
- 2) An additional' minimum of 82,000 gallons (71,800 gallons from the-Reactor-Coolant Bleed Holdup Tank, 7600 gallons from the Concentrated Boric Acid Storage Tank, 2600-gallons from the Letdown Storage Tank)
?of makeup water is available which can be supplied at 50 gpm and would extend the time to initial fuel assembly uncovering by approximately 27 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br /> (98 hours0.00113 days <br />0.0272 hours <br />1.62037e-4 weeks <br />3.7289e-5 months <br /> total).
- 3) With normal operator action, a 50 gpm leak would be detected and any
' fuel in transfer return to either the Spent Fuel Pool or the Reactor
. Vessel within approximately one to.two hours.
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B It is concluded from the above that more than adequate time is available for activation of Reactor Building sumps, isolation of the Spent Fuel Pool, positioning of any fuel assembly in transfer either in the Reactor Vessel or Spent Fuel Pool, and dewatering the Reactor Building Refueling Canal for locating and repairing any leak that may develop, however remote the potential for' leakage may be.
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