ML25325A344
| ML25325A344 | |
| Person / Time | |
|---|---|
| Site: | 07103104 |
| Issue date: | 11/21/2025 |
| From: | Garcia-Santos N Division of Fuel Management |
| To: | Vierling R US Dept of Transportation (DOT), Office of Hazardous Materials Safety |
| References | |
| CAC 001942, EPID L2025-DOT-0001 | |
| Download: ML25325A344 (0) | |
Text
OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY -PROPRIETARY INFORMATION Request for Additional Information Japanese Competent Authority Certificate No. J/2007/AF Docket No. 71-3104 Revision No. 0 Model No. NT-XII This request for additional information (RAI) identifies information needed by the U.S. Nuclear Regulatory Commission (NRC) staff (the staff) in connection with its review of the application.
The staff used the International Atomic Energy Agency (IAEA) Specific Safety Requirements No. 6 (SSR-6), Regulations for the Safety Transport of Radioactive Material, 2018 Edition, in its review of the application.
Each RAI describes information needed by the staff to complete its review of the application and to determine whether the applicant has demonstrated compliance with the regulatory requirements of IAEA SSR-6, 2018 Edition.
Materials Evaluation RAI-Ma-1 Describe consensus codes and standards that are followed for design, fabrication, qualification testing, and acceptance inspections of packaging receptacle welds to ensure that the welds maintain their structural integrity for normal and accident conditions of transport. If a consensus code or standard is not followed for design, fabrication, qualification testing, and/or acceptance inspections of packaging welds, describe the methods or controls that are implemented to ensure that packaging welds are adequately designed, fabricated, tested, and inspected to meet structural performance requirements for normal and accident conditions of transport.
Examples of consensus codes and standards that address design, fabrication, qualification testing, and acceptance inspection of safety-related welds for nuclear applications include those published by the American Society of Mechanical Engineers (ASME), the American Welding Society (AWS), and analogous consensus codes and standards published by national or international standards organizations.
The application documents the use of welded joints for the packaging receptacles. The staff noted that the application does not include information concerning the codes, standards, and/or other specifications that are followed for design, fabrication, qualification testing, and inspections of weld joints in the packaging receptacles. The staff must review this information to ensure that packaging welds are adequately designed and constructed to meet structural performance requirements for normal and accident conditions of transport.
This information is needed to determine compliance with the requirements in Paragraphs 640, 648, and 673 of IAEA SSR-6, 2018 Edition.
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OFFICIAL USE ONLY -PROPRIETARY INFORMATION RAI-Ma-2 Describe consensus codes, standards, and/or other methods that are implemented to ensure that package maintenance activities are adequate to detect the effects of corrosion in stainless steel and alloy steel packaging components, such that components can reliably perform their safety functions throughout the period of use. The staff requests that this description addresses the following criteria:
a.
Inspection methods (e.g., bare metal visual exams) and visual criteria for detection and characterization of localized corrosion effects such as pits, crevice corrosion, and chloride induced stress corrosion cracking (SCC) for stainless steel items, as well as for detection and characterization of corrosion for alloy steel nuts. Examples of visual indications that may indicate potential corrosion 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.
b.
Inspection equipment and personnel qualification requirements (e.g.,
lighting and visual acuity requirements for performing visual exams) ensure reliable inspections that can adequately detect and characterize indications of localized corrosion and chloride induced SCC prior to component failure or loss of safety function.
c.
Describe surface cleaning requirements to ensure that bare metal visual inspections of component surfaces are capable of detecting surface flaws, and for ensuring adequate removal of surface deposits such as salts and other chemicals that may contribute to localized corrosion and SCC of stainless steel components and corrosion of alloy steel nuts.
d.
Describe 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.
The package handling and maintenance criteria described in Chapter III of the application do not include any inspections to detect and evaluate indications of corrosion to ensure that components with unacceptable corrosion are repaired or replaced prior to a loss of safety function. Stainless steel is susceptible to localized corrosion effects, including loss of material due to pitting and crevice corrosion, when exposed to marine and road spray environments. Chemicals present in these environments tend to gradually degrade the protective passive oxide film on stainless steel surfaces over extended service periods leading to the formation of pits and crevice corrosion. Stainless steel components under high tensile stress (such as weld residual stress) exposed to these environments are also susceptible to the formation of cracks due to chloride-induced SCC.
Alloy steel nuts are also susceptible to corrosion if the protective plating becomes damaged or deteriorates during routine use. Adequate visual inspections performed by qualified personnel using qualified techniques are needed in order to detect and evaluate indications of localized corrosion and SCC of stainless steel components exposed to aqueous outdoor air environments and corrosion of alloy steel nuts so that personnel can reliably determine the need for corrective
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OFFICIAL USE ONLY -PROPRIETARY INFORMATION action, such as repair or replacement of components that show unacceptable indications.
This information is needed to determine compliance with the requirements in Paragraph 613A of IAEA SSR-6, 2018 Edition.
RAI Ma-3 Describe and provide the criteria for visual inspections of polymer foam impact absorbers that are performed for package maintenance to detect indications of wear or other mechanical deterioration to determine the need for repair or replacement.
The package handling and maintenance criteria described in Chapter III of the application do not include any visual inspection criteria for detection of aging degradation of polymer foam impact absorbers. The evaluation of aging in Section II-F of the application appears to credit such inspections as a basis for determining that aging degradation of polymer foam impact absorbers is not a concern during the period of use of the packaging.
The staff identified that even though the polymer foam inside the packaging receptacles is not susceptible to aging degradation due to the heat, radiation, and chemical reactions, routine loading, unloading, handling, and transport operations, it can lead to wear or other types of mechanical deterioration over the service life of the packaging.
This information is needed to determine compliance with the requirements in Paragraph 613A of IAEA SSR-6, 2018 Edition.
Structural Evaluation RAI-St-1 Include the definition inner receptacles in the safety analysis report (SAR).
In the SAR, the term inner receptacles is used several times but is not defined.
The term inner receptacle is an outdated term for fuel receptacle. As stated in SSR-6, 2018 Edition, Paragraph 306, and IAEA SSG-26, Revision 1, 2018 Edition, Paragraph 306.4, consistent terminology should be employed for items relied on for safety including use, maintenance and inspection.
This information is needed to determine compliance with the requirements in Paragraph 306 of IAEA SSR-6, 2018 Edition.
RAI-St-2 Update the upper bound of the component normal design temperature to 70 degrees Celsius (°C).
In the SAR, the upper bound of the normal operating temperature is set at 67°C as shown in Table II-A-1 and used in the pressure calculation in section A.4.6.
This temperature is based on the result from section B.4.2. However, in the IAEA SSR-6, Paragraph 639, defines the temperature range for the package components as -40 to 70 °C.
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OFFICIAL USE ONLY -PROPRIETARY INFORMATION This information is needed to determine compliance with the requirements in Paragraph 639 of IAEA SSR-6, 2018 Edition.
RAI-St-3 Clarify whether the impact from the dedicated lashing components on a vehicle to the outer receptacle shell has been considered during normal transport.
In SAR section A.4.5, the applicant noted that the packaging to be transported is not equipped with any lashing devices but should be tied down with steel wires or dedicated lashing components on a vehicle or in a transport container. Because the steel wire could introduce additional stress resulting from the acceleration defined in the IAEA SSG-26, it is not clear to the staff how the package behaves in such situation as required by IAEA SSR-6, Paragraph 612. Any features added to the package at the time of transport that are not part of the package shall not reduce its safety function.
This information is needed to determine compliance with Paragraphs 612 and 638 of IAEA SSR-6, 2018 Edition.
RAI-St-4 Clarify whether the stress from the free drop has been considered with the stress resulting from the ACT thermal test.
In SAR section A.9.2.3.3, the applicant stated that the packaging subject to the accident conditions of transport or ACT thermal test resulted in a maximum circumferential stress generated by the increase in internal pressure due to the fuel rod surface temperature of [This information was information withheld per 10 CFR 2.390.]°C was [This information was information withheld per 10 CFR 2.390.] MPa, which is small compared to the criterion value of [This information was information withheld per 10 CFR 2.390.] MPa, indicating that the design satisfies the criteria and is safe. However, it is not clear to the staff whether this stress result considered the deformation of the fuel rod due to the free drop, which resulted in a bent [This information was information withheld per 10 CFR 2.390.] by a maximum of [This information was information withheld per 10 CFR 2.390.] at the lowest span as stated in SAR section A.9.2.1.5. The cumulative stress from these two tests shall be considered as required by SSR-6, 2018 Edition, Paragraph 726.
This information is needed to determine compliance with Paragraphs 726 and 728 of IAEA SSR-6, 2018 Edition.
Operations RAI-OP-1 Clarify what actions are required if an abnormality is identified during lifting inspections.
In Chapter III-B Paragraph B.7 of the SAR, the maintenance instructions specify visual inspection of the lifting attachment of the fuel receptacle and outer receptacle to ensure that there are no harmful, scratches, cracks, etc., and that there are no abnormalities in terms of shape, etc. However, unlike other subsections (e.g., III-B.1, III-B.5, III-B.10), III-B.7 does not describe any actions if the acceptance criteria are not met.
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OFFICIAL USE ONLY -PROPRIETARY INFORMATION This information is needed to determine compliance with the requirements in Paragraphs 503(a), 608, and 609 of the IAEA SSR-6, 2018 Edition.