ML24094A207
| ML24094A207 | |
| Person / Time | |
|---|---|
| Site: | 07103103 |
| Issue date: | 03/27/2024 |
| From: | Garcia-Santos N, Bhavin Patel Storage and Transportation Licensing Branch |
| To: | Boyle R US Dept of Transportation (DOT), Office of Hazardous Materials Safety |
| References | |
| CAC 001794, EPID L-2023-DOT-0004 | |
| Download: ML24094A207 (2) | |
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Page 1 of 2 High Level Feedback on SKODA MTR/TRIGA Transportation Package Structural Evaluation
- 1. The SAR documents compliance to Czech authority regulations (reference 1) requirements. The staff needs to have a crosswalk from the Czech regulations to the IAEA SSR-6, 2012, requirements to ensure compliance with SSR-6.
- 2. The applicant did not provide a benchmarking evaluation to validate the adequacy of the nonlinear dynamic structural analysis software, ABAQUS, and relevant material models for the shock absorber (impact limiter), the cask and the baskets (Reference 2). The application should include a properly documented model validation with applicable experiments or testing data as appropriate. For example, an analytical models ability to capture relevant model output such as deceleration time history and plastic deformations can be demonstrated by comparing the physical test data of a similar package that was drop tested and which represents behavior of this package. The test data used to validate or benchmark the analytical model should be similar to the behaviors of interest for the expected package. For instance, an analytical model with impact limiters should be benchmarked using a prototype or scaled tests of a package that also has impact limiters and has a geometrically similar configuration and materials of construction. The benchmarking evaluation also needs to address any scaling effects of the package testing.
- 3. In reference 2, the applicant did not provide analyses methodology. The applicant discusses ABAQUS computational model and evaluation of the results of the analysis/calculations in sections 4 and 5, but did not describe the analysis methodology, i.e. did not provide any details about the type of analysis performed (e.g. elastic, elastic-plastic, non-linear, quasi-static, dynamic), how the impact forces on package components were determined, how different load effects are combined (i.e. pressure, temperature, load drop), did not provide maximum accelerations that were determined for different drop configurations, whether any dynamic load factors considered, how the responses in the component material were determined, etc.
- 4. The applicant did not clearly define the structural design criteria with an adequate basis and detailed justification for acceptance of the MTR/TRIGA transport cask and other components equivalent plastic deformations under the free drop conditions. The applicant in Reference 2, section 5 provides criteria for evaluation of the results of the mechanical resistance analyses, but there is no clearly established limits and their basis for acceptance of equivalent plastic deformations in the cask, containment closure system, baskets and other components design under the normal conditions of transport (NCT) and accident conditions of transport (ACT).
- 5. In Reference 2, the analyses have shown plastic deformation in the closure bolts of the containment secondary lid. Inelastic deformation of the containment closure and seal system is generally unacceptable for the containment evaluation and discouraged by the guidance in NRCs Standard Review Plan (NUREG-2216) for the transportation of radioactive material within the USA. Also, it conflicts with the applicants acceptance criteria (to remain within elastic limits) established in previous cask analyses in
Page 2 of 2 Reference 3 and 4. In Reference 2, section 6, the applicant arbitrarily defines a maximum 7% equivalent plastic deformation to be considered as an acceptable uniform elongation without any basis, tests, or justifications. The applicant should first avoid any plastic deformation in the containment seal region, if possible, or should establish true strain limits (assuming ABAQUS results output is true strain) based on the minimum uniform elongation requirements of the specified bolt material technical specification and the material stress-strain curve, and demonstrate availability of adequate clamping force in the bolts to maintain required compression for the containment seal elements under the ACT combination of applicable loads to comply with the leak tightness requirement.
- 6. In Reference 2, section 2, the applicant identified material for package components, but does not classify the types of steel (e.g. carbon or stainless). Also, the material properties tables list values of material parameters (e.g. Rm, Rp0.2, A), which are not defined in the document. Need to define all parameters.
- 7. The applicant needs to address the NCT free drop evaluation by demonstrating compliance to the IAEA SSR-6 performance requirements of the package under the NCT. In reference 1, section 2.1.1, the NCT free drop requirement is not evaluated, as the applicant considered it to be a subset of the free drop evaluation under the ACT.
However, the IAEA SSR-6 package performance requirements of the package under NCT and ACT are different, and therefore, need to be evaluated separately, unless the NCT package performance requirements are already met under the ACT free drop evaluations.
Reference Documents:
- 2. Ae 21723/Dok, Rev. 00, -KODA MTR-TRIGA Cask - Mechanical Resistance Calculation
- Transport
- 3. Ae 11543/Dok, Rev 2, Transport and Storage Cask for Spent Fuel from Research Reactors, (-KODA VPVR/M Cask), Safety Documentation for Type Licensing, Decree 317/2002 Col