ML23131A100
| ML23131A100 | |
| Person / Time | |
|---|---|
| Site: | 07103098 |
| Issue date: | 05/05/2023 |
| From: | Garcia-Santos N Storage and Transportation Licensing Branch |
| To: | Boyle R US Dept of Transportation (DOT), Office of Hazardous Materials Safety |
| Shared Package | |
| ML23101A187 | List: |
| References | |
| EPID L-2023-DOT-0002, A33010 | |
| Download: ML23131A100 (6) | |
Text
Request for Additional Information, MSB Materials Review, Application for DOT Revalidation Japanese Competent Authority Certificate of Approval No. J/2009/AF For the Model No. GP-1 Package Against the 2018 Edition of IAEA SSR-6, Regulations for the Safe Transport of Radioactive Material RAI-M1 through RAI-M5: Changes to Information on Package Materials Identified by the Materials Review Staff:
(Note to NRC RAI reviewers: None of the specific material changes addressed in RAI-M1 through RAI-M5 below were identified or explained by the applicant in its list of changes for the 2022 version of the GP-01 SAR.)
RAI-M1 Please address whether the new sentence quoted below describes a new material, new subcomponent, and/or modification to an existing material and/or subcomponent for a safety-related component the GP-1 package. If so, please explain the reason for this change and justify how it is suitable for its intended safety-related application.
2022 GP-01 SAR, Page I-3 (pdf p. 4), third to last sentence of the paragraph under Section II, Lid of outer receptacle states The surface of aluminum honeycomb cover are applied to two (2) anti-interference spacers of neoprene rubber 2 mm in thickness. The staff noted that this specific sentence is not included in the 2018 version of the GP-01 SAR. The reason for this change is not clear to the staff, and it is not explained in the revalidation application submittal.
This information is requested in order to verify compliance with the requirements of the 2018 Edition of IAEA SSR-6, Paragraphs 614 and 648.
RAI-M2 Please address whether the new underlined text quoted below represents a new material, new subcomponent, and/or a modification to an existing material and/or subcomponent for a safety-related component of the GP-01 package. If so, please explain the reason for this change and justify how it is suitable for its intended safety-related application.
2022 GP-01 SAR, Page I-4 (pdf p. 5), last two sentences of the paragraph under Section VIII, Fusible plugs state A fusible plug is installed in the center of each face of the outer receptacle and lid of the outer receptable (six pieces in total). The melting temperature of solder is approximately 180 °C. The staff noted that the corresponding location in the 2018 version of the GP-01 SAR does not include the underlined text. The reason for this change is not clear to the staff, and it is not explained in the revalidation application submittal.
This information is requested in order to verify compliance with the requirements of the 2018 Edition of IAEA SSR-6, Paragraphs 614 and 648.
RAI-M3 Please address whether the changes shown in Table I-1 (described below) for the rubber items of the outer receptacle lid represent a new material, new subcomponent, and/or a modification
to an existing material and/or subcomponent for a safety-related component of the GP-01 package. If so, please explain the reason for the changes and justify how they are suitable for the intended safety-related application.
2022 GP-01 SAR, Page I-10 (pdf p. 11), Table I-1, Major Materials for the Packaging Components (1/2) lists outer receptacle lid components and materials including an Anti-interference spacer made of Neoprene rubber (chloroprene rubber) and Fire-resistant rubber made of Ethylene propylene rubber. The staff noted that the corresponding rubber subcomponent information for the outer receptacle lid in this table in the 2018 version of the GP-01 SAR lists only a Spacer made of Fire-resistant rubber rather than the two separate rubber items identified in the 2022 version. The reason for these changes is not clear to the staff, and it is not explained in the revalidation application submittal.
This information is requested in order to verify compliance with the requirements of the 2018 Edition of IAEA SSR-6, Paragraphs 614 and 648.
RAI-M4 Please explain the reason for the change in the temperature ranges specified for the inner receptacle flange O-ring in the first two sentences in Section C.2.3, Gasket and welds of containment system on page II-C-2 of the 2022 version of the application. Considering the information from the application cited below, please justify how the new temperature ranges in these sentences are consistent with the service temperature range of -50 °C to +180 °C specified for the inner receptacle flange O-ring in Section B.3, Characteristics of Packaging Components (page II-B-4) and the upper service temperature limit of 180 °C specified for this O-ring in Section C.3, Normal Conditions of Transport, Subsection (1), Thermal Test (page II-C-2).
The first two sentences in Section C.2.3 of the 2022 version of the GP-01 application state: The material (silicone rubber) of the O-ring provided on the inner receptacle flange maintains its thermal strength in a temperature range from -40 °C to +38 °C. Deterioration does not occur in the material in the temperature range of -40 °C to 38 °C. The staff noted that the corresponding sentences in the 2018 version of the SAR specified different temperature ranges of -50 °C to
+180 °C (first sentence) and -40 °C to +70 °C (second sentence). The staff noted that the changes to these temperature ranges in the first two sentences in Section C.2.3 of the 2022 version of the GP-01 application appear to be inconsistent with the service temperature range specified in Section B.3 and the upper service temperature limit specified in Section C.3, Subsection (1), as cited above.
This information is requested in order to verify compliance with the requirements of the 2018 Edition of IAEA SSR-6, Paragraphs 616 and 639.
RAI-M5 Please explain the reason for the changes in the atom densities for the nuclides that are specified for the package component materials in Table II-E-1, Atom Densities of Materials Used for Calculations on page II-E-10 of the 2022 version of the application.
The staff noted that the atom densities for the nuclides that are specified for the package component materials in Table II-E-1, Atom Densities of Materials Used for Calculations (page II-E-10) in the 2022 version of the application have changed significantly from those specified in
this corresponding table in the 2018 version of the application. The reason for the changes is not clear to the staff, and it is not explained in the revalidation application submittal.
This information is requested in order to verify compliance with the requirements of the 2018 Edition of IAEA SSR-6, Paragraph 673, 682, and 726.
RAI-M6 through RAI-M10 Changes to Package Application to Address Evaluation of Aging for Package Components, Required by 2018 Edition of IAEA SSR-6:
RAI-M6 Please provide a complete evaluation of fatigue for the reusable package components for the 80-period of use (and the 160 transports that are allowed during the 80-year period) that considers the combined effects of all applicable types of accumulated stress cycles in components during normal service conditions, including the cycle types listed in items 1 through 4 below. If certain types of stress cycles are considered to be not appliable or negligible for certain components, then include an explanation of this.
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, then describe how periodic maintenance inspections of the package components will inspect for fatigue cracks in components, and describe 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.
- 1. Lifting cycles - The staff recognizes that these cycles are already evaluated in Section A.4.4.10 and Section II-F, Tables 1 and 2. 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. 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. Inner receptacle pressurization cycles - The staff recognizes that these cycles are already evaluated in Section A.4.6.3 and Section II-F, Tables 1 and 2. However, the staff noted that the inner receptacle pressurization cycles are evaluated without considering other types of stress cycles that may also be accumulated by the inner receptacle components. To perform an adequate analytical evaluation that demonstrates sufficient safety margin against fatigue failure of these components, the combined effects of accumulated pressurization 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 inner receptacle components should be considered.
- 3. Vibration cycles - The staff noted that Sections A.4.7 and Appendix 3 to Section II-A of the application provide an evaluation that demonstrates that package resonance is a not a concern considering package vibration caused by vehicle transport over bumpy road conditions. However, the staff noted that this evaluation only evaluates the peak vertical acceleration experienced by package components based on the natural frequency of the
package and the peak vertical acceleration and excitation frequency generated by the truck driving over road bumps. 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 a very large number of vibration cycles resulting from the 160 allowed transports of the package (with each transport experiencing long distances over potentially bumpy roads), along with the accumulation of other applicable types of stress cycles, including consideration of the cycle types listed herein.
- 4. Thermal stress cycles - The staff could not locate any evaluation of the potential for fatigue of components that accounts for accumulated thermal stress cycles in components. Thermal stress cycles may occur in components due cyclical fluctuation of spatial temperature gradients within components and cyclical temperature fluctuations for assembled or joined components made of dissimilar materials that are dimensionally constrained, such as the chrome-molybdenum steel bolts in tight contact with the threaded holes in stainless steel receptacle components.
In order to determine that fatigue as not an aging concern, as indicated in Section II-F, 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, is needed.
The complete fatigue evaluation that considers all applicable cycle types should demonstrate adequate protection against fatigue failure based on the applicable fatigue failure curve for the material. If such a complete fatigue evaluation cannot be performed, or if the fatigue evaluation cannot show adequate protection against fatigue failure, then periodic maintenance inspections of package components should include the examination of components for early stage fatigue cracks, and corrective actions (analytical flaw evaluation with follow-up inspections, repair/replacement of components with cracks, etc.) should be specified for detected fatigue cracks.
This information is requested in order to verify compliance with the requirements of the 2018 Edition of IAEA SSR-6, Paragraphs 503(e), 613, 613A, and 809(f).
RAI-M7 Sections A.4.4.10, A.4.6.3, and Section II-F, Tables 1 and 2 evaluate lifting cycles and inner receptacle pressurization cycles by considering stress amplitude, which is defined in these sections as one-half the total stress range for each cycle for the most highly stressed locations.
Please confirm that this definition of stress amplitude for the stress cycles corresponds directly to the definition of stress amplitude for the material fatigue failure curves for stainless steel and chrome-molybdenum steel.
This information is requested in order to verify compliance with the requirements of the 2018 Edition of IAEA SSR-6, Paragraphs 613 and 613A.
RAI-M8 Please describe any national or international codes, standards, and/or other methods, programs, or procedures that are implemented to ensure that package maintenance activities (including visual inspections, screening and evaluation of visual indications, and corrective actions such as component repairs and replacements) are adequate to manage the effects of aging in metallic package components that would see long-term use, such that the package
components are capable of performing their requisite safety functions throughout the period of use.
The staff requests that this description address the following criteria:
- 1. Inspection methods (e.g., bare metal visual exams and/or other types of nondestructive exams such as liquid penetrant exams or ultrasonic exams) for detection, characterization, and sizing of localized aging effects such as cracks, pits, and crevice corrosion.
- 2. Inspection equipment and personnel qualification requirements (e.g., lighting and visual acuity requirements for performing visual exams) to ensure reliable inspections that can adequately detect and characterize indications of localized aging effects prior to component failure or loss of safety function.
- 3. Visual criteria for detection of aging effects such as early stage fatigue cracks (if fatigue cannot be screened out by analytical evaluation per RAI-6 above) and localized corrosion of stainless steel components, such as chloride induced stress corrosion cracking (SCC), pitting, and crevice corrosion. Examples of visual indications that may indicate potential localized corrosion of stainless steel components include the accumulation of atmospheric deposits such as salts, buildup of corrosion products, rust-colored stains or deposits, and surface discontinuities or flaws associated with pitting, crevice corrosion, and/or SCC.
- 4. Describe any surface cleaning requirements that are implemented to ensure that bare metal visual inspections of component surfaces are capable of detecting surface flaws, and for ensuring adequate removal of atmospheric deposits such as salts or other chemical compounds that may contribute to localized corrosion of stainless steel components.
- 5. Describe any flaw evaluation methods (such as flaw sizing and flaw analysis methods) and associated flaw acceptance criteria that may be used to determine whether components containing flaws are acceptable for continued service.
This information is requested in order to verify compliance with requirements of the 2018 Edition of IAEA SSR-6, Paragraphs 503(e), 613A, and 809(f).
RAI-M9 The maintenance inspections are described throughout Sections II-F, II-G, and III-B as voluntary inspections. Please address whether or not maintenance inspections are truly voluntary or whether they are actually required to be performed to ensure that reusable package components are maintained in a condition to ensure they are capable of performing their requisite safety functions in accordance with applicable regulatory requirements.
This information is requested in order to verify compliance with requirements of the 2018 Edition of IAEA SSR-6, Paragraphs 503(e), 613A, and 809(f).
RAI-M10
Please address whether the maintenance criteria described in Section III-B of the application are applicable to both the packaging components and the components of the contents that are used repeatedly. If the maintenance criteria described in Section III-B do not include the components of the contents that are used repeatedly, please describe the maintenance activities, including inspection and component repair/replacement criteria, that are performed for the content components that are used repeatedly.
The aging evaluation in Section II-F of the GP-01 application includes both packaging components and components of the contents that are used repeatedly. Per Section II-F, Subsection F.2, Evaluation of the need to consider aging in safety analysis, components of the contents that are used repeatedly include the stainless steel pellet storage box, stainless steel pellet storage box assembly structural items, and borated stainless steel intermediate partition plate neutron absorber.
The maintenance criteria described in Section III-B of the application describe periodic visual inspections of packaging components, including internal and external surfaces of the body and lid of the inner and outer receptacle, welds, nuts and bolts, rubber items such as spacers and skids, boronic stainless steel plates, lifting attachment welds, and O-rings. The maintenance criteria indicate that packaging components that do not satisfy the visual inspection criteria are to be repaired or replaced. However, it is unclear whether the periodic visual inspections and repair/replacement criteria are also applicable to the components of the contents that are used repeatedly, as specified in Section II-F, Subsection F.2.
This information is requested in order to verify compliance with requirements of the 2018 Edition of IAEA SSR-6, Paragraphs 503(e), 613A, and 809(f).