ML20129E402

Requests Addl Info Re 850219 Application for Approval of Model MH-1A,including Impact Analysis Considering Combined Effects of Impact & Ambient Temp & Statement of Assumptions for Finite Element Analysis

ML20129E402
Person / Time
Site:	07106639
Issue date:	05/31/1985
From:	Macdonald C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Garrison R ENERGY, DEPT. OF
References
NUDOCS 8506060480
Download: ML20129E402 (5)

Text

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. '7 Ho639 FCTC: RHO N,1 g 71-6639 Cg gers11W5 Department of Energy .

ATTN: Mr. Roy F. Carrison DP-122.2 liashington, DC 20545 Gentlemen:

This refers to your application dated February 19, 1985, requesting approval of the flodel No MH-1 A package.

In connection with our review, we need the information identified in the enclosure to this letter.

Please advise us within 30 days from the date of this letter when this infonnation will be provided. The additional information requested by this letter should be submitted in the form of revised pages. If you have any questions regarding this matter, we would be pleased to meet with you and your staff.

Sincerely, l Or.sgg

%n,3 3 R.

"W by  !

Charles E. NacDonald, Chief I Transportation Certification Branch Livision of Fuel Cycle-and Material Safety, fi?iSS i

I'

Enclosure:

As stated 1

Distribution: w/ encl Docket File  :

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Departnent of Energy f*odel No. flH-1A Package Docket No. 71-6639 Enc 1 to ltr dtd: N STRUCTURAL

1. On page _2.1-3, the application specifies allowable stress criteria for the cask. I!owever, the application does not show that the stresses in the cask meet this criteria. !!any of the stresses reported in the application exceed allowable values. The application should show explicitly that the stresses in the cask are within allowable linits under both normal and accident conditions. Regulatory Guides 7.6 and_7.8 may be helpful in this regard. Also, note that certain bending stresses at the edge joint of the square pressure vessel should be classified as primary stresses (see definition of Secondary Stress in Regulatory Guide 7.6).

2. The discussion presented in the application for oblique drop is not adequate. The application should evaluate the stresses that would be produced under oblique impact orientations and by secondary impact and show explicitly that these stresses are within allowable limits. Also, because the cask is not a shell of revolution, the application should evaluate the cask in the most damaging angular orientation about its longitudinal axis (i.e., the effects produced by rotating the square containnent vessel).

3. The application does not consider the conbined effect of all the loads which act sinultaneously on the containment vessel. For example, the impact analysis should consider the combined effects of impact and ancient tenperature (differential thermal expansion / contraction).

Regulatory Guide 7.8 specifies an acceptable set of load combinations.

4. The application does not adequately consider the following loads in -

evaluating stresses in the containaent vessel:

a. The lateral pressure that would be exerted by the lead against the containment vessel under 30-foot end, corner, and obluque orientations not adequately(the nodel horizontal this phenomena spring)used

. in the anslysis does

b. The axial stresses that would be produced by differential thernal expansion / contraction of the-inner shell, lead shielding, and the outer shell.

c. The lateral pressure that would be exerted by the lead against the containnent vessel due to differential thernal contraction at the -40'F and -20*F tenperature conditions specified in 10 CFR 9971.71 and 71.73.

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5. The buckling evaluation in the application is not adequate to show that the inner shell does not buckle under 30-foot drop test conditions,

a. The application does not consider possible inelastic buckling (note that stresses in the shell were calculated to be above yield).

b. The application does not consider the conbined effect of all loads that would be acting sinultaneously on the containnent vessel'shell (e.g., inpact forces, nocents, and shear, lateral pressure of the lead due to inpact, and axial and lateral differential thermal expansion / contraction).

c. The application does not specify a factor of safety against buckling or show the interaction equations that will be used to evaluate the conbined effects of different types of loads acting sinultaneously.

G. The presentation of the finite elenent analysis is not clear in that nany important aspects of the analysis has not been discussed in detail. All assunptions should be stated clearly and justified.

Additional infomation is needed as follous:

a. Justify the finite element r:odel adequately represents the cask. Discuss in detail the capabilities of each type of clenent selected for the nodel including the input requirements and output obtained.

b. Justify the boundary conditions used at the horizontal centerline of cask where all nodes are constrained in all directions for all loading conditions.

c. Identify the nechanical and naterial properties used in the analysis for the elenents of the nodel.

d. Identf fy the loads and the distribution of loading in each analysis.

e. Identify the procedure to conbine different loads (i.e.,

R.C. 7.8 load conbinations).

f. Provide the rationale of using the average element stress at nodal points instead of using the elenent stresses directly.

The procedure for averaging stresses at the node where two or more elenents connected together is confusing and should be explained in nore detail. For instance, it is not clear how the average stresses are derived for different types of elenents connected together or for elenents that do not intersect each other in the same plane (i.e., outer shell and the fins). In addition, the procedure to derive principal stresses and stress intensities at each location should be identified.

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7. . Based on dynanic and static test results reported in Sandia Laboratorys' Report fio. SLA-74-0159, we believe' the redwood crushing stress used in the impact liniter analysis is non-conservative for redwood crushed perpendicular or at an angle to its wood grain. Judging from the assunptions nade for redwood crushed area and the conpressibility, it is clear that the small safety nargin does not provide adequate

- assurance to prevent redwood botton-out before all the inpact

. energy is dissipated. In addition, there are reasons to believe

.that.the embedded corrugated cylinders will increase the inpact force significantly higher than stated in the application.

3; .The application does not analyze the cask for nornal transport conditions which could produce governing stress.

9. The application does not report the stresses in the closure bolts' or in the drain / vent lines which pass through the lead shielding.

10. The application does not consider potential displacement of shielding due to " lead slunp."

11. - The puncture evaluation does not consider potential collapse of the top closure plate or the botton end plate.

12. The application does not analyze the stresses in the botton end plate of the cask or in the botton plate of the containnent vessel.

THEPJ4AL The emissivity values chosen for the stainless steel appear to be low.

Provide the reference itens to justify these values.

OPERATitlG PROCEDURES

1. Step 42 on pages 7.1-10,19, and 28; Step 46 on page 7.1-33; and Step 50 on page 7.1-47 provide instructions relative to nonitoring cask' surface tenperature prior to shipment to verify compliance with $71.43(g). The accessible cask surface, when the cask is assembled for shipment, is the fire shell. Discuss the rationale for selecting a location above the fire shell to nonitor cask surface temperature.

2. In Section 7.3.1, Steps 1, 3, 4, and 5 are not consistent with the conditions being discussed.

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_4 ACCEPTAt:CE TESTS AI'D f tAlf!TEf!ANCE PROCT!A"

1. An instruction should be added to the second paragraph in Section C.2, fiaintenance Program, requiring a check on the noisture content of the uood whenever the steel sheathing has been breached. An acceptance criteria should be given.

2. Paragraph C.2.7, !11scellaneous, should be expanded to require a check on the noisture content of the wood if initial inspection reveals coisture in the steel sheathing.

lHANIUf1 AllFiINUT1 Af!D SILICIDE FUEL.S Your request of April 15, 1985, concerning additional fuel types should be incorporated into the safety analysis for the package. This should include a physical description of the fuel and reactivity analyses as nay be appropriate.

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