ML20206G846
| ML20206G846 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 04/06/1987 |
| From: | Bernero R Office of Nuclear Reactor Regulation |
| To: | Taylor J DAIRYLAND POWER COOPERATIVE |
| References | |
| TASK-03-02, TASK-3-2, TASK-RR TAC-51867, NUDOCS 8704150174 | |
| Download: ML20206G846 (4) | |
Text
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April 6, 1987 0
Docket No. 50-409 o
Mr. James W. Taylor General Manager Dairvland Power Cooperative 2615' East Avenue South La Crosse, Wisconsin 54601
Dear Mr. Taylor:
SUBJECT:
STACK FAILURE IN WIND EVENTS (TAC 51867)
Re:
La Crosse Boiling Water Reactor (LACBWR)
By letter dated Se?tember 9, 1986, we sent you cur NRC staff safety evaluation of the LACBWR Consequence Study.
Section 3.1 of our safety evaluation addressed the performance of the LACBWR and Genoa-3 stacks in wind and tornado events.
We determined that your assessment of the ability of the two stacks to withstand tornado events is conservative with respect to an independent assessment performed by our consultant, FRC, and is therefore acceptable.
However we r performanceoftheLACBWRanddenoaequestedthatyoufurtherevaluatethe 3 stacks under straight wind loadings and show that the probability.gf damage to the LACBWR containment from stack failure is less than 10 per year at the 95% confidence level.
By your letter of January 14 1987, you provided results of further analysiswhichshowsthat,wlthcertainconservatismsremoved,the probability conditions set forth in our letter of September 9, 1986 are satisfied for the two stacks in question.
This resolves our concerns regarding wind / tornado damage as a significant contribution to overall risk.
Sincerely, t.1,~ a 51swdBy8 174 070406 LwL -. bomuro h
DCK 05000409 PDR p
Robert M. Bernero Director DivisionofBWRLIcensing cc:
See next page.
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Mr. James W. Taylor Dairyland Power Cooperative La Crosse Boiling Water Reactor cc:
Fritz Schubert. Esquire Mr. Lanning Smith, Chief Engineer Staff Attorney Wisconsin Public Service Commission Dairyland Power Cooperative Post Office Box 7854 2615 East Avenue South ifadison, Wisconsin 53707 La Crosse, Wisconsin 54.601 Mr. Kevin P. Gallen Newman & Holtzinger, P.C.
1615 L Street, NW Washington, D.C.
20036 Mr. John Parkyn, Plant Manager La Crosse Boiling Water Reactor Deiryland Power Cooperative P. O. Box 275 Genoa, Wisconsin 54632 U.S. Nuclear Regulatory Commission Resident Inspectors Office Rural Route #1, Fox 276 Genoa, Wisconsin 54632 Town Chairman Town of Genoa Route 1 Genoa, Visconsin 54632 Chairman, Public Service Commission of Wisconsin Hill Farms State Office Pullding Madison, Wisconsin 53702 Regional Administrator, Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137
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Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO SEP TOPIC NO. III-2, WIND / TORNADO EVENTS IPSAR SECTION N0. 4.6 LACROSSE BOILING WATER REACTOR DOCKET N0. 50-409 1.0 Introduction In our NRC staff safety evaluation of the LACBWR Integrated Consequence Study, we requested that Dairyland further evaluate the performance of the LACBWR and Genoa-3 stacks under straight wind loading,andshowthattheprobabilityofthecontainmentbuildingfor LACBWR being damaged by wind-induced stack failure is less than 10 per year at the 95% confidence level.
By your letter of January 14, 1987, you provided results of further studies to demonstrate that the probability condition set forth for the stacks in question is satisfied.
2.0 Evaluation The staff has reviewed your analysis which is summarized as follows.
In the case of the Genoa-3 stack, the stack is 500 feet tall and is located 400 feet from the LACBWR containment building.
During a high windspeed event the stack would have to fail within the bottom 100 feet and remain intact to land on the containment. building.
The loading profile during a high wind event is such that the failure would occur between 250 and 350 feet above the ground.
Should failure occur in that elevation range, the falling stac( would not reach the containment building.
Therefore, the Genoa-3 stack is no threat to the containment building.
In the case of the LACBWR stack, the stack is 350 feet tall and is located 12 feet from the containment building.
A previous conservative analysis showed that the stack could withstand the 100 year design straight wind which would correspond to 90 mph at 30-feet elevation. A new analysis has been performed with conservatisms removed to determine the straight wind speed the LACBWR stack can withstand.
Using the approariate exposure category as given in ANSI A58.1-1972, the stack is capaale of withstanding a straight wind speed of 161 mph.
The straight wind speed that corresponds to
-4 the probability of 10 per year is 159 mph, thyg the capability to withstand a high straight wind is within the 10 per year probability value, if no account is taken for wind direction.
However, the study presents that if the probability of the high wind blowing from the direction necessary for the stack to impact the containment is also taken into account, the probability of a high straight wind event that could result in chimney failure and would causg6the stack to impact the containment building is less than 6.5 x 10 A study was also performed to determine the effect of straight wind saeed to overturn the LACBWR stack due to foundation failure.
Using tie appropriate exposure category, the stack will withstand straight winds of 138 mph before overturning from foundation failure._4The estimated probability of exceeding this wind speed is 7 x 10 per year at the 95% confidence level.
But again taking into account the wind direction necessary for the stack to hit the containment building duetosigckfoundationfailure,theprobabilityofsuchaneventis 4.6 x 10 per year.
Since the foundation is more limiting than the stack,theprobabilityofahighstraightwindeventthatwouldrgsult intheLACBWRstackhitting_ghecontainmentbuildingis4.6x10 per year, which is less than 10 per year and is therefore acceptable.
In summary, this resolves our concerns raised in our Septemb'er 9, 1986 letter regarding possible damage to the LACBWR containment building resulting from the LACBWR stack or the Genoa-3 stack falling onto the containment building during a high windspeed event.
- 3. 0 Conclusion Based on our review of the licensee's analysis, the staff concludes that the potential consequences of stack failure are sufficiently low that such failure is not a significant contribution to overall risk associated with operation of LACBWR.
Principal Contributor:
R. Bevan Dated:
April 6, 1987
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