ML24281A144
| ML24281A144 | |
| Person / Time | |
|---|---|
| Site: | OPTIMUS-L |
| Issue date: | 10/11/2024 |
| From: | Storage and Transportation Licensing Branch |
| To: | NAC International |
| Shared Package | |
| ML24281A143 | List: |
| References | |
| EPID L-2024-LLA-0019 | |
| Download: ML24281A144 (1) | |
Text
Request for Additional Information Model No. OPTIMUS-L Transport Package Docket No. 71-9390 Revision No. 4
By letter dated July 8, 2024 (Agencywide Documents Access and Management System
[ADAMS] Accession No. ML24191A044), NAC International (NAC) submitted an amendment request to revise the current NAC OPTIMUS-L Certificate of Compliance (CoC) No. 71-9390, Revision No.3, to allow shielded devices with special and normal form sealed sources as authorized contents of the package.
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.
Each individual 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 Title 10 of the Code of Federal Regulations (10 CFR) Part 71.
2.0 STRUCTURAL EVALUATION
2-1 Demonstrate that the material properties of the Celotex material compare favorably with the results of simulations that were performed at different strain-rates that were expected during the required regulatory drop. Alternatively, provide simulations that show the performance of the material model with other strain-rates over a range that encompasses the anticipated strain-rates during a drop.
The applicant acknowledged that the Celotex material properties are strain-rate dependent and has performed LS-DYNA simulations with a material model that control the performance of the Celotex material in simulated drop tests using a strain rate of 50 in/in/sec. The Celotex performs as a shock absorber reducing the effect of the impact, maintaining the safety of the package without unacceptable release of contents. As such, staff seeks confirmation that the model will be able to simulate a material response at strain-rates that will be achieved during an actual impact.
This information is required to determine compliance with 10 CFR 71.71(c)(7) and 71.73 (c)(1).
2-2 Explain how the Celotex material properties associated with the different strain-rates are modeled in LS-DYNA to be able to adequately capture the full range of the Celotex response over the duration of the deceleration of a regulatory drop impact.
The finite element code LS-DYNA is used to develop the material model in the simulation of the drop. Since the properties of Celotex are expected to vary at different strain-rates, the staff needs assurance that this behavior is adequately modeled and that a realistic material model can capture the physical response of the Celotex and correctly represent the safety performance of the package.
This information is required to determine compliance with 10 CFR 71.71(c)(7) and 10 CFR 71.73 (c)(1).
Enclosure
2-3 Provide the confined test material properties of Celotex.
The staff notes that the Celotex used in the packaging is under confined conditions, constrained by the canister, while the material test results available followed an unconfined test protocol. The staff also notes that the safety performance of the Celotex to limit impact with the canister shell is impacted by the performance of the Celotex under confined conditions and that the packaging material will be under confined conditions during impact (the protective shell over the foam).
The applicant needs to provide the material properties used in the material model effected by confinement as well as an assessment of this effect on the impact loading of the Celotex.
This information is required to determine compliance with 10 CFR 71.71(c)(7) and 10 CFR 71.73 (c)(1).
2-4 Provide a table comparing the impact loads from drops on the containment canister vessel (CCV) to those from the referenced OPTIMUS -L calculations.
The applicant has stated that the stresses in the CCV is lower than those in the OPTIMUS-L approved cask design. However, the applicant has not justified that the impact loads from the new payload do not exceed the stresses in the approved cask design. The comparison table is intended to verify that the approved cask design envelopes the loads from the new payload and that safety is maintained.
In addition, safety analysis report (SAR) section 4.2.3 and section 4.3.3 refer to section 2.6 and section 2.7 when stating there is no loss or dispersal of radioactive contents during normal conditions of transport (NCT) and hypothetical accident conditions (HAC),
but this does not address the current amendments content and structural analysis of section 2.12.
This information is required to determine compliance with 10 CFR 71.71(c)(7) and 71.73 (c)(1).
3.0 THERMAL EVALUATION
3-1 Explain and clarify that the thermal models thermal properties (e.g., thermal conductivity, maximum allowable temperature during NCT and HAC) of the packages fiberboard insert material described in the SAR (e.g., section 3.5.4.1 of the application, table 3.5.4-1 of the application) are the same as provided in the report titled Celotex Structural Properties Tests (document WSRC-TR-20000-00444).
Section 2.12.6.3 of the application indicated that the packages fiberboard is consistent with the fiberboard (with density of 19.1 lb/ft 3) tested in the Celotex Structural Properties Tests report (SAR chapter 2, reference 2.32). However, section 2.12.6.3.1, section 8.1.5.3, and drawing 70000.14-095 of the application specify that the package fiberboard has a density between 14 lb/ft3 and 16 lb/ft3 and there was no explanation that thermal properties (e.g., thermal conductivity, maximum allowable temperature) would not change with a different fiberboard density.
This information is needed to determine compliance with 10 CFR 71.35.
3-2 Clarify that the dunnage (i.e., shoring) within the Shielded Device Insert Assembly (SDIA) and CCV will have maximum allowable temperatures greater than the allowable and calculated temperatures provided in sections 1.2.15 and 3.5.4 of the application.
Section 1.2.2.4 of the application noted that the free space between the Shielded Device and the radial wall of the SDIA will have dunnage to limit movement of the Shielded Device during transport. The materials associated with dunnage were not included and, therefore, it is uncertain whether the materials have allowable temperatures greater than or equal to the 300 °F temperature listed in section 1.2.1.5, or the temperatures reported in table 3.5.4-1 of the application.
This information is needed to determine compliance with 10 CFR 71.35.
3-3 Clarify the effects (e.g., hydrogen concentration, maximum normal operating pressure and HAC pressure within the CCV) of flammable gas generation from radiolysis and thermolysis due to the presence of unspecified dunnage (i.e., shoring) as well as the polyvinyl alcohol (PVA) glue and fiberboard materials, which are components of the SDIA and potential dunnage.
Section 2.12.6.2.1 of the application indicated that PVA is used during the fiberboard construction. Although section 2.12.6.2.2 of the application said there were no known mechanisms for reaction of the fiberboard/PVA with other components, it did not address the potential for radiolysis and thermal degradation of dunnage, fiberboard and the PVA, which could result in flammable gas (e.g., hydrogen) accumulation and higher pressures within the CCV containment boundary (e.g., undefined pressure analysis for this content). For example, NUREG/CR-6673 Hydrogen Generation in TRU Waste Transportation Packages noted that PVA has a G(H2) value of 3.1 for gamma radiation.
This information is needed to determine compliance with 10 CFR 71.43(d).
4.0 CONTAINMENT EVALUATION
4-1 Provide the radionuclides and activity of the content within the sealed sources in order to define the content that would be transported. Confirm that the sealed sources have a corresponding U.S. Department of Transportation certificate.
Section 1.2.2.4 of the application indicated that the amendments proposed content includes sealed sources that are not limited to listed devices. Although table 5.5-10 of the application included some descriptions of listed source content, these details were not included in the Shielded Device Restrictions provided in section 1.2.2.4. In addition, section 5.5.4 mentioned that the analyzed sources were described as generic devices and sample devices, indicating there can be undefined content (e.g., radionuclides, activities).
This information is needed to determine compliance with 10 CFR 71.33.