ML23033A523
| ML23033A523 | |
| Person / Time | |
|---|---|
| Site: | 07109330 |
| Issue date: | 02/10/2023 |
| From: | Yoira Diaz-Sanabria Storage and Transportation Licensing Branch |
| To: | Shuler J US Dept of Energy, Office of Packaging and Transportation |
| Shared Package | |
| ML23033A521 | List: |
| References | |
| EPID L-2022-LLA-0009 | |
| Download: ML23033A523 (1) | |
Text
SAFETY EVALUATION REPORT Docket No. 71-9330 Model No. ATR-FFSC Package Certificate of Compliance No. 9330 Revision No. 16
SUMMARY
By letter dated June 6, 2022 (Agencywide Documents Access and Management System Accession No. ML22158A271), the U.S. Department of Energy (DOE or the applicant) requested an amendment of the Certificate of Compliance (CoC) No. 9330 for the Model No.
ATR-FFSC package.
DOE requested an increase of the payload weight limits for the Advanced Test Reactor (ATR)
Low Enriched Uranium (LEU) and Missouri University Research Reactor (MURR) LEU fuel element configurations from 50 to 59 lb., an increase of the maximum package weight from 290 to 299 lb. for all configurations, and an increase of the maximum fissile mass for the COBRA LEU fuel element configuration from 435.8 to 450.0 g U-235.
Finite element (FE) models were developed using the ABAQUS CAE software to establish the basis for shipping heavier LEU fuel elements. The models include a benchmark test with a lighter High Enriched uranium (HEU) fuel content to benchmark the model and to address the free drop scenarios of the heavier LEU fuel required in Title 10 of the Code of Federal Regulations (10 CFR), Part # 71 during normal conditions of transport (NCT) and hypothetical accident conditions (HAC). The results of these analyses demonstrated that the heavier content did not affect the packages ability to perform its criticality control safety function.
DOE demonstrated that the Fuel Handling Enclosure (FHE) designs for ATR LEU fuel elements and MURR LEU fuel elements, with a different design from the ones used for the corresponding HEU fuel elements, that had been authorized in Revision No. 15 of the CoC, are no longer necessary and that the same FHE designs, used for HEU fuel elements meet, in both cases, all applicable regulatory requirements.
The review of the applicable ATR FFSC SAR documentation found that the technical approach used to develop the FE models was representative and appropriate, that the results produced by the FE analyses were correctly interpreted and consistent with the SAR, and that the results and conclusions reported provide a reasonable assurance of the safety for the package. The submittal was evaluated against the regulatory standards in 10 CFR Part 71, including the general standards for all packages, standards for fissile material packages, and performance standards under NCT and HAC The certificate has been amended based on the statements and representations in the application. The staff agrees that the changes do not affect the ability of the package to meet the requirements of 10 CFR Part 71.
EVALUATION The ATR FFSC is a two-part packaging consisting of the body and the closure. The 73 long body is a SS304 weldment that consists of an 8x8x0.1875 outer shell square tubing and a 6 diameter inner shell tubing that is 0.12 thick. There are three 1 thick stiffening plates secured to the round tube by fillet welds at equally spaced intervals. The tube is wrapped with thermal insulation, and the insulation is overlaid with a 28-gauge SS304 sheet. The SS304 sheet maintains the insulation around the inner shell. This insulated weldment is then slid into the outer square tube shell and secured at both ends by groove welds. The body weighs approximately 230lbs empty. The closure weighs approximately 10 lb. and is equipped with a handle. The closure engages with the body using a bayonet style design. There are four lugs, uniformly spaced on the closure, that engage with four slots in the mating body feature. The closure is secured by retracting two spring-loaded pins, rotating the closure through approximately 45º, and releasing the spring-loaded pins such that the pins engage with mating holes in the body. When the pins are properly engaged with the mating holes, the closure is locked. A cover is placed over the closure handle during transport to render the handle inoperable for inadvertent lifting or tiedown. Figure 1.2-5 of the SAR illustrates the placement of the handle cover. As an option, the closure handle may be removed for transport rather than installing the handle cover.
The applicant revised both the write up and the tables in Chapter 1 to show that (i) ATR LEU fuel elements are used with the ATR FHE, (ii) the MURR LEU fuel elements are used with the MURR FHE, (iii) the ATR LEU CSI is now equal to 4.0, (iv) the maximum fissile mass of the COBRA LEU fuel element is now 450g, (v) the maximum gross weight of the ATR FFSC package is now 299 lb. and (vi) remove licensing drawings for the ATR LEU FHE (60501-110) and MURR LEU FHE (60501-111) from the list of the drawings for this package.
CHAPTER 2 STRUCTURAL EVALUATION 2.1 Weight and Center of Gravity The maximum gross weight of the ATR FFSC package is 299 lb., a 9 lb. weight increase from the previously approved maximum allowable weight of 290 lb. The packaging component weights are summarized in Table 2.1-1 and payload and maximum package weights are summarized in Table 2.1-2 of the SAR.
The location of the center of gravity (CG) of the package is identical to the value of the location of the CG for the previous ATR FFSC package, which was reviewed and accepted in the SAR, Revision 15. Due to a symmetry of design and no dimensional changes of the ATR FFSC package, the CG of the package is located essentially at the geometric center of the package.
Regardless of the payload, the CG remains 35 inches from the face of the closure end and 4 inches from the bottom and sides of the package.
The NRC staff confirms that the applicants statements are accurate and acceptable, and those weights and CG are utilized for the structural analysis to meet both NCT and HAC requirements of 10 CFR 71.
2.2 Lifting and Tiedown Standards Lifting Devices: The applicant used identical design criteria and methodologies, previously reviewed and accepted in Rev. 15 of the SAR, to calculate the lift lug forces and the attachment capacity of the ATR FFSC package. The results of the calculation are provided in Section 2.5.1 of the SAR. The NRC staff reviewed the results and confirmed that they are acceptable because the calculated maximum lift lug force is less than the limit of 300 lbs. and the lifting devices have a minimum margin of safety (MS) of 2.47 indicating that that the lifting devices are safe since the calculated MS is greater than the required MS of 0.0, where the MS is defined as a ratio of
[(capacity/demand) - 1.0].
The staff determines that the application meets the regulatory requirements of 10 CFR 71.45(a).
Tiedown Devices: The applicant used identical design criteria and methodologies, previously reviewed and accepted in Rev. 15 of the SAR, to calculate the tiedown capacity of the ATR FFSC package. The results of the calculation are provided in Section 2.5.2 of the SAR. The NRC staff reviewed the results and confirmed that they are acceptable because the tiedown devices have a minimum MS of 0.46, which is larger than the required MS of 0.0.
The NRC staff determines that the application meets the regulatory requirements of 10 CFR 71.45(b).
2.3 Normal Conditions of Transport Compression: 10 CFR 71.71(c)(9) requires that the ATR FFSC package must be subjected, for a period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, to a compressive load applied uniformly to the top and bottom of the package in the normal transport position. The applicant used the compressive load of 1,495 psf, which is the 5 times the weight of the package of 299 lbs. The applicant calculated a maximum compressive stress of 54.2 psi, which is significantly smaller than the critical buckling compressive stress of 2,271 psi. Based on the calculation, the applicant concludes that buckling of the ATR FFSC package due to the compression load is not a concern for the ATR FFSC package. The NRC staff reviewed the calculations and found the conclusion acceptable.
The NRC staff determines that the ATR FFSC package satisfies the regulatory requirements of 10 CFR 71.71(c)(9).
Penetration: 10 CFR 71.71(c)(10) requires that a bar of hemispherical end, weighing at least 13 lb. be dropped from a height of 40 inches onto the most vulnerable part of the packaging.
However, the applicant stated in Appendix 2.12.1 Certification Tests on CTU-1 of the SAR that the ATR FFSC package weighing approximately 299 lb. was previously subjected to the much more demanding test of being dropped from 40 inches onto the puncture bar described in 71.73(c)(3) without experiencing any damage which could compromise confinement or criticality control. Therefore, this test does not need to be performed again, and the penetration test requirement is satisfied. The NRC staff confirmed the statement and found the conclusion acceptable.
The NRC staff determines that the ATR FFSC package satisfies the regulatory requirements of 10 CFR 71.71(c)(10).
2.4 Hypothetical Accident Conditions of Transport The NCT and HAC evaluations of the ATR FFSC package carrying a heavier LEU fuel load were performed using multiple analytical and modeling approaches. A benchmark model of the first three drops of the drop test sequence for the lighter fuel load was developed to establish model reliability. After model reliability was established, NCT and HAC evaluations for the integrity of the swage, retention of the closure, integrity of the pins, enclosure, and fuel plates were performed.
For the benchmark model and the heavier fuel models, the swage load was approximated. This model was used to create the boundary conditions to create a swage joint release load between 125 lbf/in and 150 lbf/in which are conservative values. When establishing the pullout load, the total load is gathered from the model results for each fuel plate that is pulled out. To establish a pullout load per inch, the total load is divided by the total plate length minus the length of the two gaps (where there is no swaging support). This was only done with plates 1, 5, 10, 15, and 19. The applicant stated that the swage mechanism was further calibrated in subsequent drop test models for the ATR LEU fuel content.
A partial model of one side plate and the ends of the 19 fuel plates that interact with it was also created. The dimensions of the model are referenced in Section 1.2.2.7 of the SAR. Plate 1 and Plate 19 have thicker ends than plates 2-18. The fuel plates are held into the side plate by what are designated as swage beams. To model the swage, the initial geometry of the fuel element is defined so that the fuel plates are in frictional contact with the side plates. Swage beams are added to the comb portions of the side plates. When the swage beams compress, the combs retract creating a frictional force between the combs and the fuel plates. Thus, a swage joint is created to retain the fuel plate.
The applicant did not consider strain rate effects because the materials used in this analysis are either not strain rate sensitive nor do they experience higher elongation to failure and higher yield strength at higher strain rates. Therefore, it can be concluded that strain rate sensitivity can be ignored. All material models are elastic-plastic bilinear and assume isotropic strain hardening. For some material models, the density was increased in order to achieve proper component mass. The enclosure and fuel element are modeled with consideration of the welds.
The applicant used a fine mesh model using an explicit dynamics formulation appropriate for impact simulations. The stated purpose of the model run (given in Section 2.0, Table 2 of the SAR) is to show that the model can reliably predict the deformation and structural performance of the enclosure under the drop events. The FE analysis included NCT 4-ft free drops, HAC 30-ft free drops, and HAC 40-inch puncture drops. The FE analysis had two goals: (i) to show that the heavier ATR LEU fuel element can remain structurally intact under worst-case impact loadings, and (ii) to show that the package closure remains in place and can retain the contents.
Appendix 2.12.4, Finite Element Analysis, of the SAR documented the detailed information for the FE analysis.
Free -Drop: The free drop model testing, which was previously performed for the approval of the ATR FFSC package, originally included a gross package weight of 290 lb. with a maximum payload weight of 50 lb. Since the LEU fuel elements are heavier than the original HEU fuel elements, an additional structural analysis needs to be performed to ensure adequate performance of the package with heavier fuels. The gross weight of 299 lb. is used in the structural analysis using the ABAQUS FE program, as shown in Table 2.1-2 of the SAR. The results of the FE analysis are provided in Section 2.12.4.5, Results, of the SAR and they are briefly summarized in the table below.
Puncture: Puncture drops were also analyzed with ABAQUS as part of the evaluation demonstrating the performance of the packaging and LEU fuel elements. The results of the FEA are provided in Section 2.12.4.5, Results, of the SAR and they are briefly summarized in the table below.
Based on the results of the FE analyses, the applicant made assessments that the heavier ATR LEU fuel elements can remain structurally intact under worst-case impact loadings and the package closure remains in place and can retain the contents under HAC. Therefore, the applicant concludes that the increased weight of 9 lb. from 290 lb.
to 299 lb. does not affect the performance of the ATR FFSC package.
The NRC staff reviewed the applicants FE model inputs (i.e., model geometry, material properties, FE model mesh size, initial and boundary conditions, selection of element types including friction elements, applied loading conditions, etc.) for the structural analysis and found them adequate and acceptable.
In addition, the NRC performed an independent confirmatory FE analysis using the ABAQUS computer code. The results of the staffs FE analysis show that the ATR FFSC package can carry the heavier fuel load. The results also show that severe damage to half the lugs and pins of the closure occurred for some cases, but the lid closure remained in place. In all cases, the fuel elements remained and confined in the enclosure and the fuel plates were not significantly damaged, so the additional weight of 9 lb. does not significantly affect the packages ability to perform its criticality control safety function.
Additionally, the NRC staff compared the results of the independent confirmatory FE analysis with the results of the applicants FE analysis and found that both results are in a good agreement. Therefore, the NRC staff concludes that the proposed request of the maximum package weight from 290 to 299 lb. is acceptable.
The NRC staff determines that the application meets the regulatory requirements of 10 CFR 71.73(c)(1) and 71.73(c)(3) for free drop and puncture, respectively.
Crush: 10 CFR 71.73(c)(2) requires that the crush test be performed on fissile material packages which have a mass not greater than 1,100 lb. and a density not greater than 62.4 lb./ft3. The ATR FFSC package has a maximum weight of 299 lb. and a volume of 2.69 ft3, leading to a maximum density of 299/2.69 = 111.2 lb./ft3. Therefore, the crush test is not applicable.
The NRC staff determines that the application satisfies the regulatory requirements of 10 CFR 71.73(c)(2).
2.5 Evaluation Findings
Based on the review of the statements and presentations in the application, the NRC staff determines that the applicant adequately described and evaluated the payload weight limit from 50 to 59 lb. for the ATR and MURR LEU fuel elements and the maximum package weight from 290 to 299 lb. and demonstrated that they do not have significant impacts on the package performance.
The drop test models demonstrated that the ATR FFSC package can carry the heavier fuel load. Severe damage to half the lugs and pins of the closure occurred for some cases, but the lid closure remained in place, and the fuel elements remained confined in the enclosure.
The NRC staff concludes that the package maintains adequate structural integrity to meet the structural requirements in 10 CFR Part 71.
Summary of the FEA Results under Hypothetical Accident Conditions Model Analysis Purpose Results No.1 - CG over top corner Benchmark study The accumulated deformation of the top drop, including 4-ft and 30-ft corner in physical test was approximately free drops 5/8 inch. In model analysis, 0.833 inch, showing acceptable model performance.
No. 2 - Flat side drop (30-ft) Demonstrate Swage integrity is maintained in followed by closure end integrity of fuel sequential model analysis.
puncture plate swage No.3 - Flat bottom end drop Demonstrate Swage integrity is maintained in (30-ft) followed by closure integrity of fuel sequential model analysis.
end puncture plate swage No.4 - CG over top corner Demonstrate Two of four bayonet lugs sheared off in drop, including 4-ft followed retention of puncture impact, two other bayonet lugs by 30-ft with closure end closure retained. Closure is retained.
puncture No.5 - Rotated side drop new Demonstrate Pins damaged but remain functional; 30-ft followed by oblique integrity of pins closure cannot rotate.
closure end puncture No.6 - CG over top corner Demonstrate Closure bayonets and pins remain drop using minimum material maximum package functional, fuel plate swages remain properties, including 4-ft and deformations intact.
30-ft free drops
CHAPTER 3 THERMAL EVALUATION Sections of this chapter were updated to remove balsa but retain the cellulose material, revise the package gross weight. The thermal evaluation was not modified.
CHAPTER 4 CONTAINMENT EVALUATION The applicant added an A2 calculation for LEU fuel that had been inadvertently omitted from the previous SAR.
CHAPTER 6 CRITICALITY EVALUATION DOE requested to increase the U-235 quantity in the COBRA LEU fuel from 435.8 grams to 450 grams and to revise the Criticality Safety Index (CSI) for the ATR LEU and MURR package from 6.25 to 4.
The staffs review considered the criticality safety requirements of 10 CFR Part 71, as well as the review guidance presented in NUREG-2216, Standard Review Plan for Transportation Packages for Spent Fuel and Radioactive Material. The following section of this safety evaluation report documents staffs review and the basis for its conclusions.
The applicant provided criticality analyses for package containing the COBRA fuel with 450 grams of U-235 and demonstrated that the package remains subcritical under NCT and HAC.
The change in the keff is minimal compared to the current allowed 435.8 grams of U-235 per package. The staff reviewed that applicants criticality safety analyses and finds that the conclusion is valid. This also is consistent with the staffs engineering judgement that a very small increase in U-235 content will not cause a significant change in keff.
The applicant demonstrated that an array of 64 packages under NCT and an array of 25 packages under HAC remain subcritical. The applicant determined the CSI following the regulatory requirements of 10 CFR 71.59 and shows that a CSI of 4 is appropriate.
The staff also reviewed the revised CSIs for the ATR LEU fuel and the MURR LEU fuel packages. The staff performed confirmatory analyses for the 25 packages under HAC because this condition is more limiting. The staff used the MCNP6.2 computer code with ENDF/B-VII cross sections. The staff finds that the keff for an array of 25 packages under HAC remains below the upper subcriticality limit by a significant safety margin.
The staff also checked the convergence of the calculation by using the HSRC option in the model. HSRC is a new capability implemented in the MCNP6 code to check if the criticality calculation has converged properly. This check is particularly important to criticality safety analyses for systems in which the fuel is distributed in aggregated blocks.
Based on the statements and representations in the application, the staff concludes that the Model No. ATR-FFSC package design has been adequately described and analyzed for criticality safety. On these bases, the staff finds that these changes do not affect the ability of the package to meet the requirements of 10 CFR Part 71.
CONDITIONS The following changes are included in Revision No. 16 to CoC No. 9330:
Item No. 3.b was revised to identify the latest application Revision No. 17, dated May 2022.
Condition No. 5(a)(2) was revised to update the gross weight of the package to 299 pounds.
Condition No. 5(a)(3) was revised to remove the licensing drawings no longer applicable nor to be used for the ATR LEU (60501-110) and MURR LEU (60501-11) fuel handing enclosures.
Condition No. 5(b)(1) was revised to remove the use of the previously approved FHE designs for ATR LEU fuel elements and MURR LEU fuel elements and indicate the new maximum fissile mass of the COBRA LEU fuel element as 450 g.
Condition No. 5(b)(2) was revised to increase the maximum total weight of contents and internals from 50 lbs. to 59 lbs.
Condition No. 5(c) was revised to show a CSI of 4 for the ATR LEU fuel.
Condition No. 11 authorizes the use of the previous revision of this certificate for approximately one year. The expiration date of the CoC is not changed.
The Safety Analysis Report, Advanced Test Reactor Fresh Fuel Shipping Container (ATR FFSC), Revision No. 17, dated May 2022, has been added to the References section of this certificate.
CONCLUSION Based on the statements and representations in the application, and the conditions listed above, the staff concludes that the Model No. ATR-FFSC package design has been adequately described and evaluated and that these changes do not affect the ability of the package to meet the requirements of 10 CFR Part 71.
Issued with CoC No. 9330, Revision No. 16, for the Model No. ATR-FFSC.
ML23033A521; ML23033A523 OFFICE NMSS/DFM/STLB NSIR/DPR NMSS/DFM/MSB NMSS/DFM/CTCFB NAME PSaverot PS JGoodridge JG TBoyce TB JPiotter JP DATE Feb 2, 2023 Feb 6, 2023 Feb 6, 2023 Feb 7, 2023 OFFICE NMSS/DFM/STLB NAME YDiaz-Sanabria YD DATE Feb 9, 2023