ML18046B261
| ML18046B261 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 02/08/1982 |
| From: | Wambach T Office of Nuclear Reactor Regulation |
| To: | Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| TASK-03-02, TASK-3-2, TASK-RR LSO5-82-02-047, LSO5-82-2-47, NUDOCS 8202100422 | |
| Download: ML18046B261 (10) | |
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February 08, 1982 Docket No. 50-255 LSOS02-047 Mr. David P. Hoffman Nuclear Licensing Administrator Consumers Power Company 1945 W. Parnall Road Jackson, Michigan 49201
Dear Mr. Hoffman:
SUBJECT:
SEP TOPIC III-2, 11 WIJirLAN_Q_ IORNA(J_Q_LOAD_Ill~-s~*---- _eAUSAQE_S __
Enclosed is 'a copy of our final evaluation on SEP Topic III-2, 11Wind and Tornado Loadings 11 Following exchanges between your staff and ours in-cluding the integrated assessment team meeting held on January 22, 1982, we have revised our previous evaluation.
I There are still por,tions of systems, components and structures that are not adequatei1y protected for the design basis tornado.
Th@se items will
- be reso 1 ved as part of the integrated assessment.
Sincerely, Thomas V.
~1ambach Operating Reactors Branch No. 5 (o't)
Division of Licensing DS t.t '"'~
Enclosure:
As stated cc w/enclosure:
See next page NRCFORM318(10-BO)NRCM0240 OFFICIAL RECORD COPY USGPO: 1981-335-960
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Mr. David P. Hoffman cc M. I. Miller, Esquire Isham, Lincoln & Beale Suite 4200 One First National Plaza Chicago, Illinois 60670 Mr. Paul A. Perry, Secretary Consumers Power Company 212 West Michigan Avenue Jackson, Michigan 49201 Judd L. Bacon, Esquire Consumers Power Company 212 West Michigan Avenue Jackson, Michigan 49201 Myron M. Cherry, Esquire Suite 4501 One IBM Plaza Chicago, Illinois 60611 Ms. Mary P. Sinclair Great Lakes Energy Alliance 5711 Summerset Drive Midland, Michigan 48640 Kalamazoo Public Library 315 South Rose Street Kalamazoo, Michigan 49006 Township Supervisor Covert Township Route 1, Box 10 Van Buren County, Michigan 49043 Office of the Governor (2)
Room l - Capitol Building Lansing, Michigan 48913 William J. Scanlon, Esquire 2034 Pauline Boulevard Ann Arbor, Michigan 48103 Palisades Plant ATTN:
Mr. Robert Montross Plant Manager Covert, Michigan 49043
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PALISADES Docket No. 50-255 U. s. Environmental Protection Agency Federal Activities Branch Region V Office ATTN:
EIS COORDINATOR 230 South Dearborn Street Chicago, Illinois 60604 Charles Bechhoefer, Esq., Chairman Atomic Safety and Licensing Board Panel U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Dr. George C. Anderson Department of Oceanography University of Washington Seattle, Washington 98195 Dr. M. Stanley Livingston 1005 Calle Largo Santa Fe, New Mexico 87501 Resident Inspector c/o U. S. NRC Palisades Plant Route 2, P. O. Box 155 Covert, Michigan 49043
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PALISADES PLANT Docket No. 50-255 SEP TOPIC III-2, WIND AND TORNADO LOADINGS I. INTRODUCTION I I.
The safety.objective of this review is to assure that seismic Category I structures are adequately designed to resist wind loading, tornado loading and tornado pressure drop loading, and that any damage to structures which are not designed for such loadings will not endanger seismic Category I structures, systems or equipment.
Also, tornado effects on emergency cooling ponds ar.e reviewed to assure that tornado winds will not prevent the water in the cooling ponds from acting as a heat sink.
REVIEW CRITERIA The currently accepted design criteria for wind and tornado loadings on structures is outlined in the Standard Review Plan (SRP) Section 3.3.1 and Section 3.3.2 and in Regulatory.Guides 1.76 and 1.117.
Tornado wind load is the governing wind load and is specified in Regulatory Guide 1.76 as 360 mph maximum wind speed and a pressure drop of 3 psi at a rate of 2 psi per second for the Palisades Plant.
Blow out panels were not used at this plant to mitigate differential pressure
- III.
RELATED SAFETY TOPICS AND INTERFACES
- 1. Tornado missile protection is evaluated under.SEP Topic III-4.A.
- 2. Structures which are to be considered as tornado resistant are designated under SEP Topic 111-1.
Page 2 of PALISADES PLANT ENCLOSURE
- 3.
Wind and tornado velocities are evaluated under SEP Topic II-2.A.
IV.
REVIEW GUIDELINES Pressures, load combinations, configurations and design features which were used in the original construction of the plant, as outlined in the FSAR and other docket files, are compared with the currently accepted criteria as described above.
Y.
EVALUATION According to Appendix A of the Palisades Plant FSAR, all seismic Category I structures were designed to withstand a 360 mph tornado wind load, which translates to a maximum externally applied ctesign pressure of 2.3 psi.
In addition the structures were designed for an internally applied pressure of 3 psi. This criteria is essentially the same as that outlined in Regulatory Guide 1.76, which is the currently accepted criteria for this loading;
- Blowout panels were not used as a design feature in this plant and the*refore the structures were stated as designed to resist the full differential pressure.
The structure design pressures for the various buildings are as follows:
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~'S Page 3 of PALISADES ?LANT ENCLOSURE STRUCTURE Auxiliary Building Auxiliary Building Addition Electrical Penetration Room Intake Structure Containment Auxiliary Feed Pump Enclosure Control Room Enclosure
- e.
WALL PRESSURE - psf (psi) 662 (4.6) 600 (4.2) 432 (3.0) 432 ( 3.0)
No value given. Licensee states *seismic load controls" Licensee states "No calculations available but this structure is below grade.
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432 (3.0)
- This structure was designed for 360 mph tornado loading and then analyzed for the loading shown.
No pressure gradient in the vertical direction was used in the design and this is consistent with respect to current criteria.
The containment building structure is more substantial than the other
- structures for which a load value 1s provided and th.erefore, by comparison, has satisfactory tornado resistance.
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l Page 4 of PALISADES PLANT ENCLOSURE Therefore, the structures listed above meet or exceed the current NRC requirements for tornado wind loading.
The safety injection storage water (SIRW) tank is located on top of the auxiliary building and is exposed to tornado wind loading.
No data is availa-ble to demonstrate the resistance of this tank or the condensate storage tank to tornado loading.
The supply and ex-haust piping for the emergency diesel generators are also located on an open area of the auxiliary building and will be subject to direct tornado loading.
No assessment of the structural adequacy of the steel frame enclosure over the spent fuel pool was found except for the statement in para-graph 5.2.l of the FSAR that both the steel frame enclosure and the SIRW tank were not designed to withstand tornado loading.
The ~teel frame should be analyzed to determine its loading capacity and an as-sessment of the consequences of failure on Category I structures, systems or components should be performed in order to determine cor-rective actions, if any.
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Page 5 of PALISADES PLANT ENCLOSURE VI CONCLUSION The tornado loading criteria used for the design of the Palisades Plant structures are, in general, in accordance with currently accepted standards.
However, the steel frame enclosure over the spent fuel pool is apparently vulnerable to tornado loading. This structure should be analyzed to determine if additional protection is required and then appropriate actions should be taken to provide such protection if necessary.
In addition, ft may be necessary to erect structural barriers in order to protect exposed Category I items.
Except for the items noted above, it can be concluded that in the event of a design basis tornado, the structural integrity of plant structures identified above will not be impaired and, in consequence, safety related systems and components located within these structures will be adequately protected and may be expected to perform necessary safety functions as required.
Tornado loadings will not prevent the ultimate heat sink from performing its necessary safety function as discussed in the Attachment.
PROBLE:*I:
HETIIOD OF
.ANALYSIS:
ATTACHMENT POSilION m: ~:,\\T[P. RE:-IOV.\\L
- n~o:*I NUCLEAR rm:i:r. l'LANT DfE~G[;';CY COOLING PONDS :SY TORNADOI:;S Nuclear Power plants require considerable amounts of water for routine cooling of the reactor and for emergency cooling as the ulti!Jate heat sink.
In a large number of cases,the necessary emergency cooling ~ater is stored in large open ponds in the plant vicinity.
Tnese large open bodies of water are subject to tornado passages, possibly resulting in removal of some of the ~ater stored therein.
The requirement for adequate water in such a pond is eophasized by the fact that it is conceivable that a tornado striking the plant vicinity would cause loss of 0££-site power thereby necessitating reactor shutdown and use of the cooling water stored in the pond.
Although point probabilities of tornado strikes are very scall, certain parts of the United States have a relatively high frequency of tornadic events resulting from relatively high frequency of occurrence of the necessary meteorological conditions during certain period of the year.
A number of factors are involved in detennning water removal from a pond.
These*
factors are:
- 1.
Size of the tornado, i.e. surface contact area~
- 2.
Translation speed of the tornado,
- 3.
Horizontal and vertical wind speeds within the tornado
- 4.
Path length of the tornado in traversing a pond,
- 5.
Relative size of the tornado to the size of the pond,
- 6.
Volume of water in the pond,
- 7.
Geographical location of the plant.
Thus applying appropriate values to the above £actors would provide an estimate of the water removed from a pond under hypothesized "worst tornado" conditions. If we consider the Regulatory Guide 1. 76 region I tornado as the "worst tornado" and apply some conservative values to the parBI:leters in*
equation 1 below, the maximum rate of wate'X' removal can*be estimated.
Also, by choosing a path across a pond, the total water removed can be estimated by equation 2.
'WR.Rk = iT r2 w p WR = (WRR) x
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(2)
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- Foroulntion suggested by R. Davies-Jones in correspondence regarding this topic dated February 11, 1973.
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- where, WRR = water removal rate from the pond r = radius of the tornado w ~ vertical velocity in the tornado p
- density of air and removed-water mix in the tornado WR = total water removed from the pond x = path length of the tornado across the pond u = translational velocity of the tornado However, taking a conservative view of tornado impact we can determine the water removal by assigning conservative values to the variables in equations 1 and 2.
The input Parameters are:
r = 46m (150 ft as stated in R.G. 1.76) w = 90 m/s (2/3 of the rotational velocity (300 mph) in R. G. 1. 76) p =mass indicated by hydrostatic head based on R.G. 1.76 pressure drop distributed over tornado volume (150 ft radius x 3280 ft deep)
Thus, the water removal rate (WRR) via equation 1 is 1.2 x 108 g/sec.
If we then assume that a minimum e~ergency pond size is 100 acre-ft.
with an average depth of 10 ft. and its length is.twice itswidth, a translational speed for a tornado of 2.2 m/s (5 mph, as stated in R. G. 1. 76) would require 33 seconds.* to traverse the di.agonal length of the pond and would result in *removal of 4 x 109 g of water based on e~uation 2.
The tot~l*volume of water in this pond is 1.2 x 10 1 cm3 or g.
Thus about 3%
of the wate; would be removed.
The factors applied presume a closed system that precludes any water replenishment either through precipitation, gravity or runoff into the pond.
In the actual case of a tornado event, precipitation, possibly.of an excessive nature, would occur in conjunction uith the tornado producing storm in addition to surface runoff that would result.
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A conservative e*stimate of water removal from emergency cooling ponds has been made sho~ing a maximum removal of. 37. of the water from a mini.mum sized pond.
If larger ponds are used,the fraction of water loss will be less.
Therefore, since most emergency ponds are not minimally designed, the effect of water removal by tornadoes docs not appear to be a safety concern unless the ponds are minimally designed.