NUREG/CR-4554, Forwards Comments on Draft NUREG/CR-4554, Puncture of Shipping Cask, Per 881003 Request

Forwards Comments on Draft NUREG/CR-4554, Puncture of Shipping Cask, Per 881003 Request

ML20196A390
Person / Time
Issue date:	11/14/1988
From:	Burnett R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Bosnak R NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
References
RTR-NUREG-CR-4554 NUDOCS 8812050338
Download: ML20196A390 (8)

Text

.

f NOV 1/.1983 MEMORANDUM FOR: Rot,ert J. Bosnak l

Deputy Director, DE, RES i

FROM:

Robert F. Burnett, Director f

Division of Safeguards

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and Transportation, hMSS

SUBJECT:

DRAFT REPORT: "PUNCTURE OF SHIPPING CASK," NUREG/CR-4554 This is in reply to your r.emorandum of Octooer 3,1988, requesting coments on a draft NUREG report.

We have reviewed the draft report. Our corrents are enclosed, W

D

. Burnett,T N r s

o t

Division of Safeguards ano Transpor.ation, HMSS

Enclosure:

As stated DISTRIBUTION:

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Corrnents on "Puncture of Shipping Casks "NUREG CR-4554_

Encl to Memo dtd: NOV 141933 1.

Page 2, first sentence, "Under... a shipping cask shoulu be tested for

..., revise to read "Under... a shipping cask should be designed for 2.

Page 3. "1.2 Objective" shculd be "1.2 Objectives and Tasks" in order to be consistent witu the text.

3.

Page 3, typographical error, it should have been 2.3 Statistical Analysis of Test Data.

4 Page 3 Section 3.1.3 should be "Mechanical Properties of Materials" and Section 3.1.4 should be revised to read "Prediction of Failure Due to Puncture."

5.

Page 6 first paragraph, "...that a Type B shipping cask should be sub-jected to a puncture test..." revise to read "...that a Type B shipping cask should be evaluated for a puncture test...."

6.

Page 7, first sentence, delete the phrase "... or an unit.minated cask...."

7.

Page 7, third paragraph, revise the first sentence to read "If an analytical approach is adopted, an analysis method should be selected and validated against existing test data." Corbine this sentence with the second para-graph on page 7 and delete the rest of the third paragraph.

8.

Page 7. Section 1.2, first paragraph, revise to read "The objectives of this study are to:

1. Examine and analyze the existing puncture test data and then use thun as the basis to derive an equation to compute design puncture thickness; 2. Develop analytical nethod of analysis as an alter-native approach to test; 3. Perforn sensitivity studies of vark Js para-reters of cask; and 4. Dplore the feasibility of implementing puncture analysis into the SCANS code."

9.

Page 13, add tht following to equation 1 E = Incipient Puncture energy u = Ultimate tensile strength of steel plata S

=

Thickness of the steel plate t

d =Diareter of Punch 10.

Page 15, equation 7 licits the maxinum applicable thickness of the puncture plate to 2.4 inch. Eut the benchnarking cask thown in Figure 3 has an outer shell plate thickness of 2.5 inch, please explain.

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11. P3ge 16. firf t paragraph, "Th9 wch: narking...a reasonable al^.i rnative to the puncture tests require '.910 CFR 71."

Revise to read

• The bench 4 marking... a reasonable diernative lo testing."

12. Page 17, Section 3.1.1, first paragraph, second and third sentences, revise l

to read "The cask bottom end and the closure head are of the same laminated J

construction as the walls having the same thickness of steel platt. ano lead i

shield shown in Figure 3.

For the sensitivity studies, several finite elament i

anslysis mdels are developed based on this basic cask geometry."

13.

Page 18. second paragraph, first sentence, "The lead and steel of the cask t

are assumed to be delsminated..." rovise to read "The leaa and the steel of r

the cask are nnt bonded...."

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14. Page 18, second paragraph, it is not clear why a friction force is assumed between the cask and the puncture bar. Also, it is inconsistent to assume

(

that the lead is corncted to the steel when it is away from the impact l

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area, i

15. Page 19, Section 3.1.2, first paragraph, the description of ;N method of I

analysis needs to be expanded ta include the ratior. ale. For instance, the f

report prescribet an initial velocity high enough to ensure nuncture of the l

outer shell.

In leaMty, the cask velocity is a constant for a 40 inch free l

tall and we are interestsd in the state of stress at the instantaneous moment of the plate being punctured.

It is also unclear why thc gradual incremen.

l tal displacements were applied at beations far away from the contact region i

for the static analysis.

16. Page 20 the references and the true stress.$ train curves of A36 steel, i

Typ1318 stainless steel, and the lead were not given,

17. page 20 Equatica 8 u s not shown, t

18. The mechanical prererties of lead st,wn in Table 2 (page 35) and referenced on page 20 is incorrect. The yield i.id tensile strength appears too high i

while the density is too low. List your source of reference.

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19.

Page 22, it is not clear why failure prediction method 1 has been named Minimum shear on an imaginary cylindrical surface. We recoezend it be re-named to Maximum transvet se shear across the thickness of the shipping

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l cask shell.

t "effective stress."

20. Page !.3, failure prediction octl.od 3, define the terr)

Section 3.1.4 (pages 22 24) should provide more descriptive infcrmation about l

t 2

21.

how the stress contours of Figures 5, 6, and 7 were generated and how the incipient puncture erergte: shown in figure 8 were computed?

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2?. The report did not ex31ain why significant local vibration, which causes stress reversals in tie impact zone and affects the accuracy of the solu-tion, was induced during impact for Model C03 but not for the other models.

23. The report concluded that the analytical approach is an excellent alterna-tive to actual testing and the failure prediction method should be the mini-mum shear stress with a factor of safety of 1.6 to be consistent with the 99percentconfidencelimit(page30). However, Equation (6) on page 15 establishes the design outer shell thickness associated with the 99 percent confidence limit for incipient puncture energy. Thus it seems that with the availability of Equation (6), both testing and analytical approach are una necessary. We recommend that Eq. (6) be implemented into SCANS.

24.

Figure 1 and Figure 16, revise u to Su.

25. The report did not specify whether the test data shown in Figure 1 were for solid plates or laminated plates. And if the test data wers for laminated plates, whether the plates were 'aacked by lead or depleted uranium.

i o

NOV 141988 MEMORANDUM FOR: Robert J. Bosnak Deputy Director, DE, RES FR0;h Robert F. Burnett, Director Division of Safeguards and Transportation, HMSS

SUBJECT:

DRAFT REPORT:

"PUNCTURE OF SHIPPING CASK," NUREG/CR-4554 This is in reply to your memorandum of October 3,1988, requesting coments on a draft NUREG report.

We have reviewed the draft report. Our coments are enclosed.

W 0

Ro t. Burnett, r

Division of Safeguards and Transportation, NMSS

Enclosure:

As stated DISTRIBUTI,0g NMSS r/f SGTR r/f NRC F/C

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Comments on "Puncture of Shipping casks "NUREG CR-4554 1

Enc 1 to Memo dtd:NOV 1 4 1988 5 -

1.

Page 2, first sentence, "Under... a shipping cask should be tested for

..., revise to read "Under... a shipping cask should be designed for n

2.

Page 3 "1.2 Objective" should be "1.2 Objectives and Tasks" in order to be consistent with the text.

3.

Page 3, typographical error, it should have been 2.2 Statistical Analysis of Test Data.

4 Page 3, Section 3.1.3 should be "Mechanical Properties of Materials" and Section 3.1.4 should be revised to read "Prediction of Failure Due to Puncture."

5.

Page6,firstparagraph,"...thataTypeBshigpingcaskshouldbesub-jected to a puncture test..." revise to read

...that a Type 8 shipping cask should be evaluated for a puncture test...."

6.

Page 7, first sentence, delete the phrase."... or an unlaminated cask...."

7.

Page 7, third paragraph, revise the first sentence to read "If an analytical approach is adopted, an analysis method should be selected and validated against existing test data." Combine this sentence with the second para-graph on page 7 and delete the rest of the third paragraph.

8.

Page 7, Section 1.2, first paragraph, revise to read "The objectives of this study are to:

1. Examine and analyze the existing puncture test data and then use them as the basis to derive an equation to compute design puncture thickness; 2. Develop analytical method of analysis as an alter-native approach to test; 3. Perform sensitivity studies of various para-meters of cask; and 4. Explore the feasibility of implementing puncture analysis into the SCANS code."

9.

Page 13, add the following to equation 1 E = Incipient Puncture energy u = Ultimate tensile strength of steel plate S

=

Thickness of the steel plate t

d = Diameter of Punch

10. Page 15, equation 7 limits the maximum applicable thickness of the puncture plate to 2.4 inch.

But the benchmarking cask shown in Figure 3 has an outer shell plate thickness of 2.5 inch, please explain, i

[

11. Page 16, first paragraph, "The benchmarking...a reasonable alternative to the puncture tests required by 10 CFR 71."

Revise to read "The bench-marking... a reasonable alternative to testing.:

12. Page 17, Section 3.1.1, first paragraph, second and third sentences, revise to read "The cask bottom end and the closure head are of the same laminated construction as the walls having the same thickness of steel plates and lead shield shown in Figure 3.

For the sensitivity studies, several finite element analysis models are developed based on this basic cask geometry."

13. Page 18, second paragraph, first sentence, "The lead and steel of the cask are assumed to be delaminated..." revise to read "The lead and tne steel of the cask are not bonded...."

14. Page 18, second paragraph, it is not clear why a friction force is assumed between the cask and the puncture bar. Also, it ls inconsistent to assume that the lead is connected to the steel when it is away from the impact area.

15. Page 19, Section 3.1.2, first paragraph, the description of the method of analysis needs to be expanded to include the rationale. For instance, the report prescribes an initial velocity high enough to ensure puncture of the outer shell.

In reality, the cask velocity is a constant for a 40 inch free f all and we are interested in the state of stress at the instantaneous rament of the plate being punctured.

It is also unclear why the gradual incremen-tal displacements were applied at locations far away from the contact region for the static analysis.

16. Page 20, the references and the true stress-strain curves of A36 steel, Type 316 stainless steel, and the lead were not given.

17. page 20, Equation 8 was not shown.

18. The mechanical properties of lead shown in Table 2 (page 35) and referenced on page 20 is incorrect. The yield and tensile strength appears too high while the density is too low. List your source of reference.

19. Page 22, it is not cicar why failure prediction method 1 has been narred Minimum shear on an imaginary cylindrical surf ace. We recommend it be re-named to Maximum transverse shear across the thickness of the shipping cask shell.

20. Page 23, failure prediction method 3, define the term "effective stress."

Section 3.1.4 (pages 22-24) should provide more descriptive information about 21.

how the stress contours of Figures 5, 6, and 7 were generated and how the incipient puncture energies shown in Figure 8 were computed?

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22. The report did not ex) lain why significant local vibration, which causes stress reversals in tie impact zone and affects the accuracy of the solu-tion, was induced during impact for Model C03 but not for the other models.

23. The report concluded that the analytical approach is an excellent alterna-tive to actual testing and the failure prediction method should be the mini-mum shear stress with a factor of safety of 1.6 to be consistent with the 99 percent confidence limit (page 30). However, Equation (6) on page 15 establishes the design outer shell thickness associated with the 99 percent ient puncture energy.

Thus it seems that with the confidence limit for incip(6), both testing and analytical approach are un-availability of Equation necessary. We recommend that Eq. (6) be implemented into SCANS.

24. Figure 1 and Figure 16, revise u to Su.

25. The report did not specify whether the test data shown in Figure I were for solid plates or laminated plates. And if the test data were for laminated plates, whether the plates were backed by lead or depleted uranium.

,