ML17054B369
| ML17054B369 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 01/28/1985 |
| From: | Schwencer A Office of Nuclear Reactor Regulation |
| To: | Hooten B NIAGARA MOHAWK POWER CORP. |
| References | |
| NUDOCS 8502050143 | |
| Download: ML17054B369 (8) | |
Text
Docket No.:
50-410 Jg~ 28 1995 Mr. B. G. Hooten Executive Director, Nuclear Operations Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, New York 13202
Dear Mr. Hooten:
Subject:
Request for Additional Information on Snow and Ice Loads at Nine Mile Point, Unit 2 In April 1984, in an FSAR Amendment, you revised your design snow loads for Category I structures to 45 psf.
This value was a significant reduction from the originally identified extreme snow load on the ground of 141 psf.
Additional information required for the staff to continue its review of the revised snow loads is identified in the enclosure.
Please provide this information within 60 days of the date of this letter.
If you have any questions concerning the enclosure, pleas'e contact the Licensing Project Manager, Mary Haughey (301-492-7897).
Sincerely,
Enclosure:
As stated RHeishman BBordenick NRC PDR Local PDR PRC System NSIC cc:
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e oo 4oo JAN 28 1985 Nine Mile Point 2 Mr. B. G. Hooten Executive Director, Nuclear Operations Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, New York 13202 cc:
Mr. Troy B. Conner, Jr.,
Esq.
Conner 5 Wetterhahn Suite 1050 1747 Pennsylvanfa
- Avenue, N.W.
Washtngton, D.C.
20006 Richard Goldsmith Syracuse University College of Law E. I. White Hall Campus
- Syracuse, New York 12223 Ezra I. Bialfk Assistant Attorney General Environmental Protection Bureau New York State Department of Law 2 World Trade Center New York, New York 10047 Resident Inspector Nine Mile Point Nuclear Power Station P. 0.
Box 99
- Lycomfng, New York 13093 Mr. John W. Kefb, Esq.
Niagara Mohawk Power Corporation 300 Erie Boulevard
'West
- Syracuse, New York 13202 Jay M. Gutierrez, Esq.
U. S. Nuclear Regulatory Comnfssfon Region I 631 Park Avenue King of Prussia, Pennsylvania 19406 Norman Rademacher, Licensing Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, New York 13202
40 0
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REQUEST FOR ADDITIONAL INFORMATION NINE MILE POINT, UNIT NO. 2, SNOW AND ICE LOAD Section 2.3. 1.3.2 of the FSAR (pages 2.3-8 and 2.3-9) originally presented a discussion of. maximum snow load, which stated "the weight on the ground of the 100-yr mean recurrence interval snow pack at the Unit 2 site is 415 kg/sq m (85 psf)."
The discussion also stated that "the extreme snow load may be conservatively estimated by adding the weight of the 48-hr probable maximum winter precipitation (assumed to occur as snow) to the 100-yr snowpack."
The weight of the 48-hr probable maximum winter precipitation was es,timated to be 273 kg/sq m (56 psf), resulting in the statement that "the extreme snow load on the ground at the Unit 2 site is estimated to be 688 kg/sq m
( 141 psf)."
The implication of these statements was that the 100-yr mean recurrence interval snowpack was considered as a severe environmental load for design load combinations and that the extreme snow load was considered as an extreme environmental load for design load combinations.
In April 1984, however, Section 2.3.1.3.2 of the FSAR was significantly amended to indicate that the weight of the 100-year snow load is 45 psf, with no discussion of the extreme snow load.
The design ground snow load for Category I structures was also identified in this amendment to be 45 psf.
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a)
Provide the bases for reducing the weight of the 100-yr snow load from 85 psf, as originally stated in the FSAR, to 45 psf as stated in the April 1984 amendment.
b)
Provide the weight of snow appropriate for consideration as'n extreme environmental load for purposes of design load combinations for Category I structures.
Consider that extreme environmental
- loads, such as the design basis
- tornado, have expected probabilities of occurrence in the range of 10 to 10 per year.
The extreme snow load should reflect the weight of snow at ground level (through a combination of events to estimate the, appropriate probability level), adjusted for expected differences between the weight of snow at ground level and the maximum weight on the roofs of safety-related structures.
As originally presented in Section 2.3.1.3.2 of the
- FSAR, an extreme snow load of 141 psf, or the appropriate combination of 100 year snow pack and 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> PMWP, is acceptable as an extreme environmental load for design load combinations with appropriate modifications for translation to roof loads.
c)
Are the Category I structures capable of withstanding the combined snow loads described in b) above?
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