ML18046A901

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Forwards Revised Draft Evaluation of SEP Topic III-4.A Re Tornado Missiles.Revision Incorporates More Detailed Structural Review,But Does Not Alter Previous Conclusions
ML18046A901
Person / Time
Site: Palisades 
Issue date: 08/28/1981
From: Crutchfield D
Office of Nuclear Reactor Regulation
To: Hoffman D
CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
References
TASK-03-04.A, TASK-3-4.A, TASK-RR LSO5-81-08-065, LSO5-81-8-65, NUDOCS 8109080080
Download: ML18046A901 (23)
v • d • e


Text

'

Docket No. 50-255 LS05-81-08-065 Mr. David P. Hoffman Nuclear Licensing Administrator Consumers Power Company 1945 i~ Pa rna 11..... Road Jackson, Michigan 49201

Dear Mr. Hoffman:

August 28, 1981

SUBJECT:

SEP TOPIC III-4.A, TORNADO MISSILES

  • PALISADES Enclosed is a revised copy of our draft evaluation of Topic 111-4.A, Tornado Missiles that was sent to you on March 4, 1981.

The.revision incorporates a more detailed structural review but does not alter our previous conclusions. Since you have not provided information that would cause us to alter our previous conclusions, our review of this topic is complete and this evaluation will be a basic input to the Integrated Assessment for your facility. This topic assessment may be revised in the future if your facility design is changed or if a~g1tional infonnation is provided to the staff.

Sincerely, Dennis M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of licensing

Enclosure:

As stated s~Y' cc w/enclosure:

See next page

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f. M:c"o6/s NRC FORM 318 (10-80) NACM 0240 OFFICIAL RECORD COPY USGPO: 1981-335-960

. a UNITED STATES NUCWAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 August 28, 1981 Docket No. 50-255 LS05-8i-08-065 Mr. David P. Hoffman Nuclea~ Licensing Administr~tor.

Consumers Power Company 1945 W Parnall Road Jackson, Michigan 49201

Dear Mr. Hoffman:

SUBJECT:

SEP TOPIC III-4.A, TORNADO MISSILES PALISAD~S Enclosed is a revised copy of our draf;t evaluation of Topic III-4.A, Tornado Missiles that was sent to you'on March 4, 198l.

The revision incorporates a more detailed structural review but does not alter our previpus conclusions.

Since you have not provided.information that would cause us to alter our previous conclusions, our review of.

  • this topic is complete and this evaluation will be a basic input to the Integrated Assessment for your facility.

This topic assessment may be revised in the future if' your facility design is changed or

.r if additional information is provided to the* staff.

Enclosure:

As stated*

cc w/enclosure:

See next page

. Sincerely,

~

/)1. &d;JLid Dennis M. Crutchfield~--:_*

  • Operating Reacto~s Branch No. 5.
  • Division of Licensing

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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 Co~any 212 West Michigan Avenue Jackson, Michigan 49201 Judd L. Bacon, Esquire Consumers Power Corrpany 212 West Michigan Avenue

  • Jackson~ Michigan 49201 Myron M. Cherry, Esquire Suite 4501 One IBM Plaza Chicag6, Illinois 60611
  • Ms. Mary P. Sinclair
  • Great Lakes Energy Alliance 5711 Summerset Drive Midland; Michigan

~8640 Kalamazoo Public Library 315 South Rose Street Ka 1 aniazoo, Michigan

  • 49006 Township Supervisor Covert Township Route 1, Box 10
  • Van.Buren County, Michigan 49043 Office of the Governor (2)

Room 1 - Capitol Building Lansing, Michigan 48913

  • Wi111am J. Scanlon, Esquire.

2034 Pauline Boulevard Ann Arbor, Michigan. 48103

... Pa-lisades Plant-... _

'.ATTN:

Mr. Robert Montross

.* Plant Manager.

Covert; Michigan 49043

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. ----*-*-* *****-*** ;..---- :.......... :.."....... *:.:........ ~*.-........ : ---

PALISADES Docket No. 50-255 O. S. Environm2ntal Protection Agency Federal Activities Branch Region. V Office ATTN:

EIS COORDINATOR 230 South Dearborn Street Chicago, Illinois 60604 Charles Bechhoefer; Esq., Chairman Atomic S.afety and Licensing Board Panel

u. S. Nuclear Reg*ulatory Corrmission Washington, O. c.

20555 Or. George c. Anderson Department of Oceanography University of wa*shi ngton Seattle, Washington 98195 Dr.*M. Stanley Livingston 1005 Calle Largo Santa Fe, New Mexico 87501 Resident Inspector c/o U. S. NRC P. O. Box 87 South Haven, Michigan 49090

/

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PALISADES TOPIC III-4.A TORNADO MISSILES REVISION 1.

I.

Introduction Tornado generated missiles could cause sufficient damage to a plant so that the actual safety of the plant is reduced. Topic III-4.A is intended to review the plant design to assure that those structures,. systems and components necessary to ensure:

1.

The integrity of the reactor coolant pressure boundary,

2.

The capab11 i ty to shutdown the reactor and maintain it in a safe shutdown condition, and

3.

The capability *to prevent accidents which could result in unacceptable offsite exposures can withstand the impact of an.appropriate postulated spectrum of tornado generated missiles.

An assessment of the adequacy of a plant to withstand the impact of torn~do mi~siles includes:

l. Determination of the capability of the exposed systems, components and

~tructures to withstand key missiles {including small missiles with penetrating characteristics and larger missiles which result in an overall structural impact),

2.

Determination of whether any areas of the plant require additional

  • protection.

II.

  • Review Criteria.
  • -The* plant desig*n was reviewed with regard to General Design *criterio.n

~ :....

2~ "Design Bases.for Protection Against Natural Phenomena," of Appendix A, "General Design Cr1teria for Nuclear Power Plants," to 10 CFR Part 50, "Licensing of Production and Utilization _Facilities," which requires, in.

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-- part, that structures, systems, and components_ important to safety be des 1gned to withstand the effects of natural phenomena such as tornadoes without loss of capability to perform their safety functions.

III.

Related Safety Topics Topic II-2.A, "Severe Weather Phenomena" describes the tornado characteristics for the plant. _ Topic III-2, "Wind and Tornado Loadings" reviews the,

capability of the plant *structures, systems and components to withstand wind loadings.

Topic VII-3, "Systems Required for Safe Shutdown" reviews those systems needed to achieve and maintain the plant in a safe shutdown condf....

ti on.

- IV. -

Review Guidelines The review was performed in accordance with Standard Review Plan (SRP) 3.3.2,-"Tornado Loadings,".3.5.3,' "Barrier Design Procedure," and 3.5.1.4, "Missiles Generated by Natural Phenomena," Revision l. SRP 3.5. L4 identifes two missile sets known as Spectrum I and Spectrum II missiles, each of :

which contains a variety of missiles and their correspo'ndirig velocity. -A

  • plant applying for a construction permit would be required to design for one of these missile sets. This SRP states that plants which were not required -

at the construction permit stage to design to the mi-ssile spectrum provided in Revision 0 to the SRP should show the capability to withstand two of the postula~ed missiles in the Revision 0 spectrum.

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The-following-missiles are describea in SRP 3~5~1.4 as being appropria-te for evaluating OL Applications for plants which were not required to be protected against the full tornado missil~ spectrum during the CP stage:

l. Steel Rod, 1 11 dia., 3**1ong, 8 lbs, horizontal velocity.:. 0.6 X total tornado velocity.
2.

Utility Pole, 13liu dia., 35'. long, 1490 lbs~, horizontal velocity =

  • 0.4 X total tornado velocity.

The systems, structures, and components required to be protected because of their importance to safety are identified in Regulatory Gui.de 1.1 l7.

V-*

Evaluation**

A.

Tornado Event Description

. -.In accordance with Regulatory Guide 1.76, the Palisades Site is in

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, Tornado Region *1, where the design basis tornado is characterized_ by_***

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  • . a maximum wind speed of 3GO mi 1 es per hour with an occurre_nce frequ~ncy _, i-_: -

of no greater than lo~ 7 per year. The tornado characteristics described

~ - '. '

in SEP Topic II-2.A, Severe Weather Phenomena, for the Palisades Site, are of similar severity. Therefore, the Regulatory Guide 1.76 tornado

  • ch-aracteristics will provide an adequate design basis,-to~nado for *.*

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Th~refore, in accbrdance with SRP 3~5.1.4, Revision 0, the total~ ~orizontal * *

. *velocity for the two postulated missiles is:

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J.- -steel Rod, 31} ft/sec.:

--~-- ~--~*- ___ ~tj l i ty Pol e, __ 21. 1. ft/sec.

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  • -* These missiles are considered to be capable of striking in all directions with vertical speeds equal to 80% of the horizontal speeds listed above.

B.

Review of Safe Shutdown Vulnerability As described in the SEP Review Writeup on Palisades Safe Shutdown Systems {Topics V~lO.B, V-11.A, V-11.B, VII-3, and IX-3 dated November 5, 1980), the following systems are needed as a ;

minimum to fulfill the shutdown ~nd cooldown functi~nal requirements and permit the plant to reach and maintain a cold shutdown condition:

1. Reactor Protection and Control Systems
2.

Auxiliary Feedwater System

3.

Main Steam *System {Main Steam Isolation Valves, Safety Valves,.

and Atmospheric Relief Valves)

4.

Service W~ter System

5.

Chemical and Volume Control System 6 *. Component Cooling Water System

'1.

Shutdown Cooling System

8. *Instrumentation for shutdown and cool down 9 *. Emergency Power (AC and DC) and control power for the above sys t~ms.

and equipment We have reviewed these systems with respect to their locations, degree

  • of protection against missiles, and the availability of backup systems.

We have found that the majority of systems and components 1 isted above>**

are adequately protected against tornado missiles: However, we have determined that some equipment important to safety is not adequately*

protected.

The following equipment was found to lack suffiCient

~-

i. protectfon against ttie potential.effects of the design tornado missiles listed above.
1.

Atmospheric Relief Valves The relief valves are adequately prQtected by a two foot concrete enclosure.

However, they discharge steam via the steam relief stacks which are located on the roof of the concrete enclosure and thus are exposed to tornado missiles.

Crimping of a sufficient number of these stacks by tornado missiles could compromise the capability for controlli.ng steam pressure. This control capability is needed in a shutdown transient once the condenser vacuum is lost.

2.

Boration Systems

. *Although most of the boradon equipment (e.g., boric *acid tanks, pumps,.and valves) are adequately protected by concrete barriers' some of it.

is indirectly vulnerable to tornado missile effects.

Speci fi cal ly, the safety injection and refueling tank (T-58) is vulnerable.

Although boric acid tanks are avaiable for initial boration in a shutdown transient, for maintainfng ;

long tenn shutdown conditions other sources of water-have to be available.

If the safety injection and refueling tank.is postulated to be damaged and unavailable, another missile protected source of water is needed to assure L

long.term borationcapability.

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- 3.

Compressed Air System The compressed air equipment (e.g. air compressors, valves, lines) is located in the auxiliary bay of the tur~ine building (below plant El. 607'-6").

The auxiliary bay roof does not appear to be suffit:ient to resist tornado missiles.

Failure of the compressed air system would affect.some of the flow paths for the Chemical and Volume Control System (CVCS).

This, for example, includes the flow paths to the pressurizer, and from boric acid tanks via boric acid pumps *.

The consequences of failure of the compressed air system would not be necessarily serious since alternate flow paths are availabl*

.which use motor operated valves~.

~

. Failure of the compressed air system would also affect the componen~ ;

  • coo.1 i ng water sys tern which a 1 so depends on air operated va 1 ves **

.The likelihood of tornado missile entry into the compressed air

  • system equipment area is believed to be less than what would be expected for

~~

a similar structural enclosure which was "exposed"-.Jrom all sides.

In the. *

  • case of Palisades,* the enclosing structure is shadowed. on three si~es by. *:-. --

.*adjacent structures (i.e. *the turbine building and the equipment withi:n the

. contafoment building, and the control r~om area structure) *. This~ in effect,-

confines eligible tornado missiles to those coming from the south side of the.<*_:::;

  • .plant *. However, quantificatio.~ of the shadowing effect on missile strike /:
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probability is not readily available wi.th currently ava-ilable analytic methods. _ Furthennore, past reviews of. actual tornado events suggest that the potential strike probability *reduction due to shadowing may not be significant when the number of missiles aloft is large *.

4.

Diesel Generators The two diesel generators used for emergency AC power are located in a portica of the auxiliary building between plant elevation 590'-0" and 613'-6".

The diesel generators* and associated equipment are adequately pro-

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. * *... tected by a minimum of 18 inches of reinforced concrete which has a* minimum specified compressive strength of 3000 PSI.

However, the diesel air intake.*

and exhaust piping is in a semi-enclosed area above elevation 613'~6". This area is open to potential tornado missiles.

P6ssible crimping of the expo*ed -

,piping could block air floy-1 and cause* the.diesels to stall just at the time when they would be needed (i.e. loss of offsite power is assumed in the event of a tornado).

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Review of Other Safety.Related Systems

  • The top of the spent fuel pool is not protect~d *against the entry of

With respect to current licensing criteri~ for.*

-~

  • new plants, all postulated-tornado IT\\issiles, *.including.- tne automobile, have

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.. the potential for entering the sp~nt fuel pool from above.

However, current **.

criteria for o*lder plants {SRP 3.5.1.4, Rev. 1,Section I.) limit the hypo-

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.. thetical missiles to the two described in Section A above.

Of these, onl~

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w the one inch steel rod is applicable, since the utility pole is limited to less than 30 feet in.elevation above grade {the top of the spent fuel pool walls is 59 feet above grade}.

The effects of the one inch steel rod have been evaluated in previous analyses (e.g~ written staff testimony and responses* to interrogatories on spent f~el pool protection against tornado missiles f6r North Anna Units 1 and 2.

The results indicate that the potential offsite.radiological consequences are wclJ within the 10 CFR Part 100 Guidelines.

In vi~w of the above considerations, we conclude that the.Palisades

D.

Structural Considerations 0.1 Wall and *Roof Thickness The followi_ng tabulated information was ob.tained from the Palisades FSAR, drawings and from information obtained during a site visit held November 17-1~, 1980.

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.. STRUCTURE OR STRUCTURAL COMPONENT DESCRIPTION/REMARKS Containment Reinforced and pre-stressed concrete

( fc-5000 psi)

  • Auxiliary Building Steel frame above elevation 649'-0" Auxiliary Building Addition Containment Penetration Room

.. *.Auxiliary Feed--

Pump Enclosure.

Emergency Personnel

  • : Access Enclosure

. at South West

  • S_i de of Reactor
  • Building
  • Elev. 625'-0" to.

. 635 I -011 Service Building Intake Structure Reinforced concrete below elevation 64~'-0" (f' - 3000 psi) c Reinforced concrete (f' = 3000 psi) c Reinforced concrete (f'c= 3000 psi)

Rei nf orce 7d concrete

,( f 'c = 3000 psi) below grade Reinforced concrete (f'c= 3000 psi-assumed)

No informatiort available Reinforced concrete lf 1~ = 3000 psi-assumed)

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\\..'All THICKIJESS ROOF THICKNESS

. 42 11 36" (dome)

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rnetal siding metal deck*

18" 18" *(scaled) 24"..

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D.2 Original Tornado Missile Design Criteria

a.

The following paragraph, applicable to the containment, was extracted from paragraph 5.1.3.2, page 5-24 of the Palisades Plant FSAR:

11 (h) Missiles The effects of the following external missiles on the containment structure were analyzed using Reference 6:

Item Weight (Lb)

Velocity (Fps) 3 11 Pipe x 10' Long*

76 620 4

11 x 12 11 Pl an\\( 12' Long

  • 104 760 Automobile 4,000 450 Flatcar 40,000 480 L.ocomot i ve 240,000 :**

310 T~rbine Generator Parts (See Section 14.11)

None of the above missiles would penetrat~,the containment exc~pt the railroad flatcar. The flatcar might penetrate but/.

would not pass through the contai nmeryt wall *. *some of the...

wires in 10 to 12 of the tendons would rupture at the point of impact but total failure would not occur.

The containment*

  • woul.d not collapse and the NSSS would not be affected."
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b. With respect to the Au xi 1f ary Building the fol.1 owing was extracted from paragraph 5.2.2, page 5-48 and 5-49 of the Palisades fSAR.

"In the design, seismi~, wind and other approptiate lateral loads have been assumed to be resisted and carried down to the foundations by diaphragm action of the slabs and the shear wall action of the wall~. Care has been taken in design to make the concrete in the building ductile to enable i*t to better resist dynamic loads (seismic, tornado and jet).

The new and spent fuel pool walls are *r"esistant to tornados and the associated ~redible missiles.~:.The enclosur~ over the fu~~ storage facilities has not been designed to resiit tornados.

However, make-up water can be added from Lake Michigan in the event that water is lost from the spent fuel p~ol due to ~ tornado or 6ther action.

The c6ncret~ en~losure, with three floo~.level~. which houses the control room, the er.iergency di esei generators and swi ~ch-gear, has been designed to*wiihstand the tornado loa~ing specified in

  • Appendix A.

In addition, this enclosure has be~n analyzed for a 600 ~ph wind in ac~ordance with ASCE Paper j269_and-found to b~

satisfactory except for local failures of doors and other small operiihgs.

The effect rif missiles such as a:~mall d*ameter pipe

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(3" x 10" long), construction plank (4" x 12" *x 12' long), automobile -

(4,000lb) flatcars (40,000 lb) and locomotive (240,000 lb) generated--*.

bi a unif<;>rm wind of 600 mp~ of infinite extent was also analyzed.

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A realistic acceleration distance of 800' was assumed to calculate*/

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  • and penetrate the walls of this. enclosure is_ the piece of small diameter pipe, but this penetration would not disrupt the operation of facilities in this enclosure due to redundancy of equipment.

The areas of this building housing tadwaste, chemical and volume control equipment, safety injection, containment spray and component coo1i ng systems are 1 ocated below grade and ;n a reinforced concrete closure. Hence they are inherently resistant to tornados.

11 The licensee noted in the FSAR *that missile effects were combined with*

other loads. Appendix A of the FSAR indicates th~t missile effects are.

combined with dead load only. Also, no specific data on actual values of ductility ratios was found.

For other Category I structures (and for the Aux:i'l i arY s*uil ding

-. as stated in the previous quotation) the tornado missile loading

  • criteria of Appendix A, pages* A-7, paragraph A.2{c)(i)c.of th~

. Palisades Plant FSAR are as follows:

"c *. Missile equivalent to a 4" x 12" x 12' long wood pla.nk traveling end-on at 300 mph or a passeng~~ auto (4,000

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pounds) flying through the air at 50 mph and at not more.

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than 25 feet ab.ave ground. * *

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... The forces due to the wind are calculated in accordance with methods described in ASCE Paper No. 3269 entitled, "Wind Forces on Structures." Applicable pressure and shape coefficients are used. There is no variation with height or gust factor.

The forces resulting f~om a tornado are combined ~ith dead loads only.

Dead loads include piping and all other permanently attached

  • or located items. There will be sufficient tim~ after si~hting a tornado to trip the reactor and remove_all signif~cant live loads such as loads ori cranes. There are no other significant live loads.*

Allowable stresses are 90% of yield strength for structural and

. reinforcing. steel unless* it can be demonstra.ted that a safe plant shutdown ~an be assured with higher stress and fnelastic deformatfon.

Allowable Jtress for concrete is SSS of. ultimate except that local crushin~ wi11* be permitted at the missile impact zone.

In all cases.

structures supporting or housing critical equipment ~re revie~ed t~

assure that deflections do not re~ult in loss of equipment function."

Also the FSAR, Page 5-50~ Section ~.3:1 states:

"Turbine Building* and Intake Structure - The following auxiliary facil.ities related to the nuclear steam supply system are located in or*near the turbine bui1ding:

A~xiliary feed pumps in the turbine building basement; Containment electrical penetration area; Service water pumps in the intake structure; and Di~sel fire pump in the intake stru~ture.

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-..,;;.* The above auxiliary facilities are located w.ithin feinforced concrete enclosures designed to withstand the loads specified in Appendix A for Class I structures including tornadoes.

In addition, the structures have been investigated for the effects of the missiles de-It scribed in Section 5.2.2. (section b above).

9nly the 3 11 pipe could pen~trate.a concrete enclosure but could not completely disrupt a vital system therein due to the redundancy of equipment."

d.

The licensee prepared and submitted {see trip report memo noted above), a comparison of the Palisades missile ~*pectrum with the missile spectrum listed in SRP Section 3.5.1.4, Rev. 0, as follows

{in part):

  • * "1. Current tornado missiles versus Palisades desfgn Wood plank, 4" Steel pipe, 3" Steel rod, l" Steel pipe,* 6 11 x '12" FSAR..

76 lb, 760 fps 76 lb, 620 fps NA

. NA.

SRP 200 1 b~ 442 fps 78.lb, 211.fps.

8 lb, 316 fps 285 1 b, 316 fps Steel pipe, -12"

  • U t il i ty po 1 e Automobile

.NA NA 4,000 lb, 450 fps 40 k, 480 fps

. 743 lb,.211 fps 1,490 lb, 211 fps*

4,000 lb, 105 fps.. ~

Flatcar Locomotive Boxcar 240 k, 310 fps 47.3 k, 500 fps NA NA NA

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.. 2. Calculations

  • Calculations checked for penetrat.ion using the modified Petry equation (reference Standard Review Plan (SRP) 3.5.3). This conforms with current SRP acceptance criteria.
a.

Containment - All missiles did not penetrate except for the flatcar below Elevation 649'.

b.

Auxiliary Building below Elevati.on 649' - did not resist 3" pip~. flatc~r. and locomotive.

c.

Intake structure - reduced. velocities t~ one half of those shown above.

Analysis *fo~ the plank, 3" pipe, and.

auto~~bile showed no penet~ation.

d. Auxiliary building addition~ containment penetration room arid auxiliary feed pump enclosure no missile cal~ulations located~ 11
  • 3. The licensee has stated that the.velocities listed in the FSAR are impact velocities and not-initial velocities chosen at some ~di.st~nce_*: *. -

from the target. This "point-of-take-6ff" is state~ as being 800 feet in the quotation no_ted in paragraph c. above._ Neither a rationale for the use of such~ proc~dure, nor details o~ the method of cal~ulatiori

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?

  • *;. ~

'~.:., ' J

    • . -- ~

could be found.

However, it is inconceivable that a 120 ton locomotive could attain a speed of 211 miles per hour iri response to tornado winds.

  • .. /

It is also not plausabl_e that such a missile could strike any s~ructure:

at that speed without causing massive damage.

-. ~

-~ --:.* *.*.*.*.

The calculations-by

~ --..:... -

- - the licensee using the modified Petry formula, as noted in the quotation in paragraph 2.e. above, are conservative.

  • C~rrent NRC requirements for concrete wall and roof thicknesses (with minimum code reinforcement) are as fol i ows:

. CONCRETE STRENGTH REQUIRED WALL REQUIRED *ROOF

( f I c in psi)

THICKNESS (INCHES)

THICKNESS (INCHES).

3000 23 18 5000 18

./

14 It can be seen from a comparison of known concrete wall and roof thick-nesses that the known dimensions of the plant concrete structures are comparable to current criteria, with the exception of the emergency

.pe~sonnel access enc1os~re walls and roof.* Based on tornado missil~

  • ca ti on NP-440 dated July, 1977). the walls of the ernerg.ency personnel access enclosure shoul~.be ~ble to withstand the SRP Section 3.5.1.4.

Spectrum II Missiles (ctirrent ~riteria). However, the roof of th~s

. enclosure may be vulnerable since it is only 8 11.thick.

Enclosed 1n this

.structure is the personnel lock which consists of a cylindrical 3/8 11 thick.

plate with door lOcks on each end.

Perforation of the roof by one of _...

~he missiles would not necessarily-~un~ture thii lock:* *Even if-t~e missile punctures the 3/8 11 plate, containment integrity can be maintained by the one door lock that enters the containment.

~-

  • . --. -,'-""*.-=;*,-*. ~.,,., **** _._.... _

. - The steel frame enclosure over the spent fuel pool is not desigried to resist tornado missile effects.

It was noted in* the SEP Evaluation for topic III~2, Wind and Tornado Loadings that this structure was not designed for tornado winds _and that this matter would be handled during the integrated assess~ent.

As stated above, only one missile is po~tulated to enter the spent fuel pool and the consequences were found to be acceptable.. Should the steel rod strike the steel frame, the consequences are judged to be minimal and would not cause collapse of the structure.

Five port_ions of exterior walls are constructed of masonry block..

The licensee has stated th~t these sections are to be removed and replaced by reinforced concrete designed to FSAR criteria as a result of Inspection and Enfo~cement Bulletin 80-11.

D. 3 Summary The Category I structures atthe Palisades plant, in gener~l, provide.

  • acceptable protection against the effects of Spectrum II -tornado missiles.

Most wall and roof thicknesses surpass current NRC requirements for penet~a-tion and scabbing.

Those that did not were judged to be ~cceptable based

  • on the EPRI tests or because consequences of the postulated missiles were found *acceptable.

The minimum wall thicknesses shown are required for Spectrum II missiles.

and not Revision 0 missiles.* Spectrum II missiles include the steel rod

t

(.!)

r

_.18-and telephone pole which are the two Revision 0 missiles postulated; however, the velocities with which these missiles travel are faster in the Revision 0 requirements than in the Spectrum II requirements.

The speeds are shown below.

Vel OCitl'. (feet/sec.)

Weight {lbs.)

Missile Spectrum I I

  • Revision 0 Spectrum II Revision 1

11 diameter steel rod 167

'317 8.8

. 8.

Utility pole 180 211 1122.

1490 It is judged that although the wall thicknesses were.found acceptable for Spectrum II missiles, they would also be acceptable for the two Revision,o missiles postulated at the higher speeds based on the EPRI tests noted earlier.

\\_.

The results of the full scal~-EPRI tests for the two Revision-0 missil~s are shown below:

Weight

  • Velocity Missile
  • pbi

{fps}*

1500*

205 Utility Pole

  • Utility Pole

.1470.

204 Panel Thickness

{in}

18 12 Concrete Strength (psi}

. 3770..

3620 Front Penetration*

(in)

.. *O.

.o

/

0

~. *..

Back face Damage Cracks*_

Cr.acks 1

11 Rebar 8

303

.. 18 12 3650 3.6

. No Damag.

8 435 5.8 3545 Cracks*

1 11 Rebar

    • *.-*.* '-=*** --~ *. *.*.
  • Full weight not effective The tests on the two missiles. which were comparable in we.ight and velocity to the Reivsion* 0 requirements. resulted in backface cracks on.a 12 11 thick panel 1 but did not result in full penetration by the missile or backface spalling.

Details of the tests can be found in Electric Power Research Institute publication EPRI-NP 440.

Calculations using the modified NDRC formula for a inch diameter steel rod traveling at 31?.feet per second re~uire approximately 8 inch {hick concrete to prevent scabbing.

Therefore, it is judged that wall t~icknesses at Palisades would be acceptable*

to prevent scabbing and penetration for the two Revision 0 missiles postulated.

It appears that gross structural.effects from missiles were considered in

  • the initial design. This should be verified. The load combinations in which the missile impact loads were used shall be reviewed in Topic III-7,B_.

VI.... Con cl us; ons Based on our evaluation we conclude that the Palisades plant meets the current criteria for Tornado'missiles protection except in the*

following areas:.

. 1.

  • The steam relief stacks of the atmospheric rel'ief vaiv*es
2.

The safety injection and refueling tank

3.
  • The compressed air sys tern 4~ The diesel generatbr air intake and exhaust pipin;.

We will evaluate the need for ptovidin9 sufficient tornado missile: *

/

  • ~.

-.. ~.

protect~-~-"_ to these sys terns during the integrated assessment for Palisade~~ : **.

-..;...-~...,,..,-_....,..:_-.-::-.-;..,. ____.

~...

  • . i:*
  • *It has been concluded after reviewing the FSAR that gross structural response has been considered for all safety-related structures in addition to local penetration for the mis'siles considered in the original design.

It is concluded that the gross structural response due to the five missiles' originally postulated would govern over the two missiles postulated in this review.

~,,.._ -..--~.-r::..\\*:.:::.*-...-:-,*,.,...*-:--* - **"'.

~

~ *-

/

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