ML23257A002

Attachment-Email Dated 5-30-23 from Ngarcia Santos (NRC) to Rboyle (DOT) Staggered Request for Additional Information for the Revalidation Recommendation of the Model No. JMS-87Y-18.5T, Structural Evaluation

ML23257A002
Person / Time
Site:	07103004
Issue date:	05/30/2023
From:	Garcia-Santos N Storage and Transportation Licensing Branch
To:	Boyle R US Dept of Transportation (DOT), Office of Hazardous Materials Safety
Shared Package
ML23257A001	List: ML23257A002 ML23257A004
References
CAC 001794, EPID L-2023-DOT-0005
Download: ML23257A002 (4)

Text

Request for Additional Information Docket No. 71-3004 Model No. JMS -87Y-18.5T Japanese Certificate of Competent Authority J/2044/B(U)F

The questions below describe information needed by the staff for it to complete its review of the application and to determine whether the applicant has demonstrated compliance with regulatory requirements.

Structural Review

RAI St-1 Provide clarification on how stress concentration effects (higher stresses in the surrounding region of local geometric discontinuities of the component parts) have been accounted for in the fatigue evaluations for the reusable package components. Justify omission of or consider stress concentration effects, where it is applicable.

The application evaluates fatigue for the lifting devices, containment device and tie-down attachments in sections (II) -A.4.4.3.3, (II)-A.10.5, (II)-A.10.6.3(11) and (II)-A.10.6.4(3) of the safety analysis report ( SAR). However, the staff could not locate any discussion on consideration of stress concentration fac tor to account for the effect of any irregularities or discontinuities of the component parts or justification thereof for not considering in the components fatigue evaluations.

The stress concentration factor is typically used to account for the effect of discontinuities such as holes, grooves or notches, bolt threads and head fillets that are not represented in detail in the finite element analysis (FEA) model.

This information is requested to determine compliance with the requirements in paragraphs 613A and 809(f) of the IAEA SSR-6, 2018 Edition.

RAI St-2 Clarify values of the maximum repetitive stress for the cask body lifting lugs considered in section (II) -A.4.4.3.3 of the SAR.

Based on the stress intensity (s) calculation at the hole of the lifting lug in section (II)-A.4.4.3.1, the staff finds that the maximum repetitive stress should be 59 N/mm2 instead of 37.3 N/mm2 considered by the applicant in the evaluation of the cask body lifting lug

This information is requested to determine compliance with the requirements in paragraphs 613A and 809(f) of the IAEA SSR-6, 2018 Edition.

RAI St-3 Verify and confirm that the stress amplitudes corresponding to the n umber of stress cycles from the design fatigue curves are properly adjusted for differences between the moduli of elasticity on the design fatigue curves and that used in the analysis of the component parts to determine allowable repeated peak stress intensity in section (II)-A.10.5 and possibly other sections of the SAR.

Section (II)-A.10.5 of the SAR, evaluates containment devices for the combined repeated peak stress intensity. In this evaluation, the allowable repeated peak stress intensity is determined by multiplying the stress amplitude corresponding to the number of stress cycles from the design fatigue curves by the ratio of modulus of elasticity on the fatigue curves to the modulus of elasticity used in the analysis. Instead, it appears to the staff that the allowable peak stress intensity

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should be det ermined by multiplying the stress amplitude by the ratio of modulus of elasticity used in the analysis to the modulus of elasticity on the fatigue curves.

This information is needed to determine compliance with the requirements of the paragraphs 613A of the IAEA SSR-6, 2018 Edition.

RAI St-4 Verify the values in the Repeated Peak Allowable Stress Intensity column of the Table (II)-A.31 and confirm if they are values of the allowable stress intensity range or values of the alternating component, which is half of the allowable stress intensity range. Update this table as necessary, which needs to be worked in conjunction with resolution of other RAIs as applicable.

Section (II)-A.10.5 of the SAR, evaluates containment device and basket components for the combined repeated peak stress intensity. Although conservative, it appears to the staff that the values in the R epeated Peak Allowable Stress Intensity column of the Table (II)-A.31 are values for the alternating component, which is half of the allowable stress intensity range from the applicable design fatigue curves. The values in this column are compared against the combined repeated peak stress intensity values per the analysis and used to derive margin of safety in the design of the components.

This information is needed to determine compliance with the requirements of the paragraphs 613A of the IAEA SSR-6, 2018 Edition.

RAI St-5 Provide a complete evaluation of fatigue for the reusable package components for the 4 0-year period of use that considers the combined effects of all applicable types of accumulated stress cycles in components during normal service conditions, including the following cycle types (as described in this question):

a. Lifting cycles

b. Pressurization cycles

c. Thermal stress cycles

d. Vibration cycles

The staff needs a complete fatigue evaluation that considers the combined effects of all applicable types of stress cycles during normal service, including consideration of the cycle types listed above. Also, the appropriate number of cycles need to be considered in fatigue evaluation depending upon the type of cycle being evaluated. If certain types of stress cycles are not applicable or negligible for certain components, explain why these are not applicable or are negligible.

If such a complete fatigue evaluation cannot be performed, or if the fatigue evaluation cannot show adequate protection against fatigue failure considering the combined effects of all applicable types of accumulated stress cycles in components, provide the following information:

a.1 a description about how periodic maintenance inspections will be used to identify and address fatigue cracks in components of the package.

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b.1 A description of the corrective actions that will be taken for any detected fatigue cracks, such as analytical flaw evaluation with follow-up inspections, repair/replacement of components with cracks, etc.

The following provide additional descriptions about accumulated stress cycles as provided in the application:

1. Lifting cycles - The staff recognizes that these cycles are already evaluated in section (II)-A.4.4.3.3 for the cask body and lid lifting device, section (II)-A.10.6.4(3) for the skid lifting device and table (II)-F.2 of the SAR. However, the staff noted that the lifting cycles are evaluated without considering the other types of stress cycles that may also be accumulated by the lifting devices for the cask body and the lid. To perform an adequate analytical evaluation that demonstrates sufficient safety margin against fatigue failure of these components, the combined effects of accumulated lifting cycles along with other applicable types of accumulated stress cycles in these components (including consideration of cycle types listed herein) on the potential for fatigue of lifting devices should be considered.

2. Pressurization and thermal stress cycles - The staff recognize that pressure and thermal cycles are already evaluated in sections (II) -A.10.5 and table II-F.2 for the containment device (i.e., cask body, lid and connecting bolts). However, the staff noted that the containment device pressurization & thermal cycles are evaluated for 1000 cycles over 30 years, which is contrary to the 40- year service life considered for the components fatigue evaluations elsewhere. Also, the staff noted that thermal stress cycles may occur in components due to cyclical fluctuation of spatial temperature gradients within components, which could exceed 1000 cycles over 40- year service life. In addition, the staff noted that this evaluation does not address the potential for fatigue of package components due to the combined effects of other types of stress cycles that may also be accumulated by the containment device components. To perform an adequate analytical evaluation that demonstrates sufficient safety margin against fatigue failure of these components, the combined effects of accumulated pressurization & thermal cycles along with other applicable types of accumulated stress cycles in these components (including consideration of cycle types listed herein) on the potential for fatigue of containment device components should be considered.

3. Vibration cycles - The staff noted that section (II)-A.4.7 provide an evaluation that demonstrates that package resonance is a not a concern considering package vibration caused by vehicle transport. The staff also recognizes that the tie-down attachments are already evaluated in section (II)-A.10.6.3(11) of the SAR for fatigue cycles. However, the staff noted that the tie -down attachment components are evaluated for 4 000 cycles, which the applicant has inappropriately considered as lifting cycles, and not as vibratory cycles. The package components could experience

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many vibration cycles from numerous vehicle transports by road during the 40-year service life, which may exceed 4000 lifting cycles considered in the fatigue evaluation. In addition, the staff noted that this evaluation does not address the potential for fatigue of package components due to the combined effects of the accumulation of many vibration cycles resulting from the allowed transports of the package over 40- year service life, along with the accumulation of other applicable types of stress cycles, including consideration of the cycle types listed herein.

To determine that fatigue as not an aging concern, as indicated in section ( II)-F of the application, the staff needs a complete fatigue evaluation that considers the combined effects of all applicable types of stress cycles during normal service, including consideration of the cycle types listed above. Also, the appropriate number of cycles need to be considered in fatigue evaluation depending upon the type of cycle being evaluated.

This information is requested to determine compliance with the requirements in paragraphs 503(e), 613, 613A, and 809(f) of the IAEA SSR-6, 2018 Edition.

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