ML21236A212

Enclosure 2: Safety Evaluation Report for Review of Revision No. 16 of the Certificate of Compliance No. 9342 for the Model No. Versa-Pac Transportation Package

ML21236A212
Person / Time
Site:	07109342
Issue date:	09/03/2021
From:	Office of Nuclear Material Safety and Safeguards
To:	Daher-TLI
Devaser N 301-415-5196 NMSS/DFM/STLB
Shared Package
ML21236A208	List: ML21236A210 ML21236A211 ML21236A212
References
Download: ML21236A212 (11)

Text

SAFETY EVALUATION REPORT

Docket No. 71-9342 Model No. Versa-Pac Certificate of Compliance No. 71-9342 Revision 16

Summary

By application dated February 17, 2021 (Agencywide Documents Ac cess and Management System (ADAMS) Accession No. ML21049A135), as supplemented on J uly 14, 2021 (ADAMS Accession No. ML21195A282), Daher-TLI, (Transport Logistics Int ernational, Inc. [TLI] or the applicant) requested revision to Certificate of Compliance (CoC ) No. 9342, for the Model No.

Versa-Pac package.

The applicant proposed to consolidate all amendment contents to Revision 12 to the Versa-Pac safety analysis report (SAR) and provided the following submitt als: (i) a summary table of the changes to the SAR, (ii) a list of the effective pages, and (ii i) a copy of the SAR, Revision 12 for Versa-Pac.

The application includes clarifications for and expansion of cu rrent contents, additional licensed contents, and added package functionality through optional use of an inner cavity foam block.

Additionally, this application revises the SAR to better prepar e for foreign validations such that the package can allow for international shipments.

The staff used the guidance in NUREG-1609, "Standard Review Pla n for Transportation Packages for Radioactive Material," as well as associated inter im staff guidance documents to perform the review of the proposed package changes. Based on t he statements and representations in the application, as supplemented, and the co nditions listed in the following chapters, the staff concludes that the package meets the requir ements of Title 10 of the Code of Federal Regulations (10 CFR) Part 71.

EVALUATION

1.0 GENERAL INFORMATION

1.1 Packaging Description

The Versa-Pac packaging consists of two designs, i.e., the VP-5 5, a 55-gallon drum, and the VP-110, a 110-gallon version. No changes were made to the pack aging.

1.2 Contents

The applicant requested to modify the CoC by adding limits for the hydrogen-limited contents at enrichments other than 20 wt% and hydrogen restricted loading t able for the VP-55 with the 5-inch pipe. The applicant is also requesting the addition of details of neutron absorbers to the

contents and sample tubes for shipping UF 6 in quantities less than 0.1 kg. Several content configurations and mass limits changes were requested. The cha nges consist of:

• Revision to the mass limits for each enrichment range for the standard configuration in CoC Table 2 for the VP-55 and VP-110, based on new criticality calculations with SCALE 6.1.3 and a revised benchmarking analysis in SAR Section 6.8,

• Addition of hydrogen limited content mass limits for 100, 10, and 5 weight percent (wt.%)

enriched uranium to the existing limits for 20 wt.% enriched ur anium in CoC Table 2A,

• Revision to the mass limits for 5 and 10 wt.% enriched uranium contents in the VP-55 with 5.0-inch pipe container in CoC Table 3, to be limited by t he volume of the pipe container,

• Addition of a new content category consisting of hydrogen limi ted (less than 1.25 lb.

(567 grams) of high density polyethylene (HDPE) equivalent) ura nium contents enriched to a maximum of 10 wt.% and 20 wt.% in 5.0-inch pipe containers in the VP-55,

• Revision to, or addition of, air transport mass limits for sev eral content categories, and

• Revision to the benchmarking analysis in SAR Section 6.8 to ca lculate enrichment-specific Upper Subcritical Limits (USLs) for the various packag e contents.

1.3 Drawings

The applicant revised one drawing, VP-55-LD, from Revision 3 to Revision 4. The drawing notes were updated to reflect optional use and details of sever al components, among them are the following:

- Certain inner containment pads made optional when shoring dev ice is provided or when paint protection is not required,

- Tolerance for Drum lid gaskets for different drum lid depths, and

- Certain components made optional for configurations that incl ude uranium oxides, metals, and TRISO fuel that are not temperature sensitive.

The changes in the revision have been reviewed and do not affec t the packages ability to meet the requirements of 10 CFR Part 71.

1.4 Evaluation Findings

The staff has reviewed the revised description of the contents and associated changes to the drawing and concludes that the requested changes continue to me et the requirements of 10 CFR Part 71.

2.0 STRUCTURAL EVALUATION

The NRC staff reviewed the Versa-Pac application to verify that the structural performance of the package meets the requirements of 10 CFR Part 71.

The NRC staff reviewed the applicants submittals and found tha t the proposed changes in SAR Chapter 2, STRUCTURAL EVALUATION, are a complete consolidatio n and re-write of the chapter without changing or adding any technical contents. The re are no changes to the design, analysis, and construction of the structural components of the Versa-Pac transportation package that are important to safety. Therefore, the proposed changes are acceptable.

2.1 Materials Evaluation

The application does not add any new materials to the packaging design. The staff verified that the proposed revisions to the package do not expose the existin g packaging materials to thermal, structural, or corrosive service environments more sev ere than those that have been previously evaluated and found acceptable by the staff in prior amendments to the CoC. The staff also confirmed that the addition of neutron absorbers (e. g., boron, hafnium, erbia, and gadolinia) as allowable contents do not introduce chemical, gal vanic, or other detrimental reactions, as these absorbers are common additions to the fissi le uranium compounds transported in the package. Therefore, the staff finds the pac kage materials to be acceptable.

2.2 Evaluation Findings

Based on review of the statements and presentations in the appl ication, the NRC staff determined that the proposed changes are acceptable and conclud es that the package maintains adequate structural integrity to meet the structural and materials requirements in 10 CFR Part 71.

3.0 THERMAL EVALUATION

Staff reviewed the application for changes to the Versa-Pac shi pping package, as described below, in order to verify that the thermal performance of the p ackage has been adequately evaluated for the tests specified for normal conditions of tran sport (NCT) and hypothetical accident conditions (HAC) and that the package design satisfies the thermal requirements of 10 CFR Part 71.

The applicant sought approval of the following changes:

1) Addition of Appendix 3.5.3 to provide temperature profiles f or the package without the containment insulation plug (Stock Number IG) to support making this part optional.

2) Added pressure maximum NCT and HAC pressure calculations.

3.1 Thermal Evaluation under Normal Conditions of Transport

SAR Appendix 3.5.3 describes the Versa-Pac thermal model that t he applicant used to perform the thermal evaluation of the package. Except for the removal of the containment insulation plug (Stock Number IG) as shown in SAR Figure 3-32, the thermal model (using ANSYS finite element code v19.1) of the Versa-Pac is the same as described i n SAR Section 3.3, which the staff has previously reviewed. The applicant performed a stead y state analysis during NCT of the Versa-Pac, without the containment insulation plug. SAR Ta ble 3-20 shows predicted

temperatures during NCT conditions. All predicted temperatures in Table 3-20 are below applicable limits. SAR Section 3.1.4 states that due to permea tion in the silicone coating of the cavity seal, the maximum normal operating pressure is expected to be near atmospheric pressure which means the containment is not a pressurized packa ge.

3.2 Thermal Evaluation under Hypothetical Accident Conditions

The applicant performed a transient thermal analysis to evaluat e the package under HAC. The initial conditions of the package, prior to the start of the fi re accident, are based on the NCT temperature distribution, as described in the SAR Appendix 3.5. 3.4. The applicants thermal model for fire analysis assumes an emissivity coefficient of 0. 9, a flame temperature of 800°C (1475°F) and a forced convection heat transfer convection coeff icient ranging between 15.6 and 17.4 W/m2-°C. The forced convection coefficient values used in the HAC analysis are lower than a measured value of about 25.5 W/m 2-°C which is typical for this type of fires 1. However, the applicant showed that the temperature increase did not resu lt in any allowable limits being exceeded, as a result of changing the convection heat transfer coefficient from 10 W/m2-°C (used in SAR Revision 12) to a maximum value of 17.4 W/m 2-°C. The staff reviewed the predicted results and observed that, in some cases, the tempera ture increase was noticeable, but margins were still large, and the staff had no concern abou t the overall thermal performance of the package.

3.3 Evaluation Findings

The staff reviewed the applicants assumptions and analysis res ults, as presented in their application, to determine consistency with NUREG-1609. The sta ff agrees with the applicant that the removal of the insulation plug will have only a minor impact in predicted temperatures, and the results support making this part optional. The staff r eviewed the pressure calculations and verified that the pressure increase is minor and does not a pproach the design pressure of the containment vessel. Based on its review of the application, the staff concludes that the thermal design has been adequately described and evaluated for the SAR changes proposed, as described in Section 3.0 of this SER, and that the thermal p erformance of the package meets the thermal requirements of 10 CFR Part 71.

6.0 CRITICALITY EVALUATION

Staff reviewed the application for changes to the Versa-Pac shi pping package, as described below, in order to verify that the criticality performance of t he package has been adequately evaluated and that the package design satisfies the criticality requirements of 10 CFR Part 71.

The following sections describe the staffs review of each of t he proposed changes listed in SER Section 1.2 above.

6.1 Standard Configuration VP-55 and VP-110

The applicant recalculated k eff for all of the models previously evaluated for the standard configuration of various enrichment uranium contents in the VP-55 and VP-110 configurations, using SCALE 6.1.3, with KENO VI and the continuous-energy ENDF/ B-VII.0 cross section library, and with the revised USLs determined in the benchmarki ng analysis in SAR Section 6.8.

The applicant used the same NCT and HAC single package and arra y models previously used

1 Thermal Measurements in a Series of Large Pool Fires, Sandia Report SAND85- 0196 TTC - 0659 UC 71, August 1971.

to determine system keff with SCALE 4.4a and the 44-group ENDF/B-V cross section librar y.

The results demonstrate that small increases in per-package 235U mass, as shown in SAR Table 6.1.2-1, will maintain system k eff below the USL for 5, 10, 20, and 100 wt.% enrichments.

For 1.25 wt.% enrichment, the results demonstrated that the mas s limit would need to be decreased to maintain system keff below the USL. All maximum keff values calculated for each enrichment, shown in SAR Table 6.1.2-1, are below the correspon ding USLs, which are summarized in SAR Table 6.1.2-8 for all content configurations.

The staff reviewed the applicants revised calculations and agr ees that there are no changes to the models other than the computer code and cross section libra ry used, and the calculated USL. The applicant has shown and the staff agrees that the Mod el No. Versa-Pac, with revised standard configuration mass limits as shown in SAR Table 6.1.2-1, will remain subcritical under NCT and HAC in single package and array configurations per the requirements of 10 CFR 71.55 and 10 CFR 71.59.

6.2 Hydrogen Limited Contents Including TRISO Fuels

The applicant requested the addition of hydrogen limited conten t mass limits for 100, 10, and 5 wt.% enriched uranium to the existing limits for 20 wt.% enri ched uranium in CoC Table 2A.

The mass limits for this content category also include TRISO fu els, consisting of uranium oxide, carbide, or nitride kernels encased within layers of carbon and silicon carbide, which may be loose or mixed in a graphite matrix and pressed into compacts o f various fuel shapes.

Hydrogenous packing material in the VP-55 cavity is limited to 1 lb. (454 grams) of HDPE equivalent. The applicant determined mass limits for the new e nrichment values for hydrogen limited contents, shown in SAR Table 6.2.2-1, using the same co nfigurations evaluated in the models for the previously approved 20 wt.% enriched uranium con tents with a Criticality Safety Index (CSI) of 0.7, as described in SAR Section 6.3.4.2. Speci fically, the applicant modeled homogeneous and heterogeneous configurations of uranium metal o f varying enrichment, optimally moderated with 1 lb. of HDPE (NCT), and mixtures of 1 lb. HDPE and varying water densities (single package and HAC). In addition, the applicant determined the effect of varying amounts of graphite being present in the NCT array evaluation. Similar to the conclusions of the analysis for 20 wt.% enriched uranium, the k eff of the NCT array optimally moderated by HDPE and graphite is significantly lower than the HAC array opt imally moderated by HDPE and water for all other enrichments evaluated. All maximum k eff values calculated for each enrichment, shown in SAR Table 6.1.2.2, are below the correspon ding USLs, which are summarized in SAR Table 6.1.2-8 for all content configurations.

The staff reviewed the applicants calculations for the 5, 10, and 100 wt.% enrichment mass limits for hydrogen limited contents in the VP-55, and agrees t hat the applicant has identified the most reactive condition for each enrichment for the single pack age, NCT array, and HAC array.

The applicant has shown and the staff agrees that the Model No. Versa-Pac, with additional mass limits for 5, 10, and 100 wt.% enrichment hydrogen limited contents in the VP-55 will remain subcritical under NCT and HAC in single package and arra y configurations per the requirements of 10 CFR 71.55 and 10 CFR 71.59.

6.3 VP-55 with 5-Inch Pipe Container

The applicant requested a revision to the mass limits for 10 wt.% enriched uranium contents in the VP-55 with 5-inch pipe container, and removal of the specif ic mass limits for 5 wt.%

enriched uranium contents. For the previously approved mass li mit for 10 wt.% enriched contents in the 5-inch pipe container, the applicant evaluated varying fissile mass and HDPE moderator within the pipe, and varying water density inside and outside the package cavity, and

in between packages in the array. The previously approved anal ysis also evaluated partial filling of the 5-inch pipe, to determine if a lower quantity of fissile material would achieve optimum moderation at a higher k eff. The applicant did not change any of the analysis parameters or assumptions, which demonstrated that for 10 wt.% uranium contents, the maximum keff occurred at the maximum evaluated mass (1,605 grams 235U). For this amendment request, the applicant provided an additional analysi s of optimally moderated fissile masses greater than 1,605 grams 235U, which demonstrated that k eff decreases with increasing mass, as shown in SAR Tables 6.5.3-3 and 6.6.3-3. This demonst rates that peak keff is obtained with the previously evaluated mass limit, and that the mass of 10 wt.% enriched uranium contents can be limited by the volume of the 5-inch pip e container. This result is bounding for the 5 wt.% enrichment contents; therefore, the mas s limits for 5 wt.% enriched uranium contents can be removed.

The staff reviewed the applicants calculations for the 10 wt.% enrichment mass limits for VP-55 with 5-inch pipe container and agrees that the applicant has id entified the most reactive condition for the single package, NCT array, and HAC array. Th e applicant has shown and the staff agrees that the Model No. Versa-Pac, with the mass limit for 10 wt.% enrichment uranium contents changed to be volume limited by the 5-inch pipe contai ner, will remain subcritical under NCT and HAC in single package and array configurations per the requirements of 10 CFR 71.55 and 10 CFR 71.59.

6.4 Hydrogen Limited Contents in 5-Inch Pipe Container in VP-55

The applicant requested to revise the CoC to add a new content category for hydrogen limited contents in a 5-inch pipe container in the VP-55. This content category consists of 10 or 20 wt.% enriched uranium contents contained within a 5-inch pipe c ontainer in the VP-55, with a maximum of 1.25 lb. of HDPE equivalent packing material in the pipe container. For 20 wt.%

enriched contents, the VP-55 is limited to one 5-inch pipe cont ainer, while for 10 wt.% enriched contents, the VP-55 may contain up to two 5-inch pipe container s. Additionally, for 10 wt.%

enriched contents, the applicant provided analyses to support t wo different CSIs: 1.0 for uranium oxides and 1.4 for all other permissible uranium forms. Similar to the previously approved hydrogen limited contents in the VP-55, uranium compou nds containing hydrogen are not authorized, and graphite not chemically or mechanically bou nd to the uranium contents, not in the fuel-free zone of TRISO compacts, or not otherwise mixed with the uranium (i.e., loose graphite) is not allowed.

The applicant evaluated hydrogen limited contents in the 5-inch pipe container in the VP-55 similar to how the standard 5-inch pipe component contents were evaluated, but with HDPE moderator limited to 1.25 lbs. Similar to all of the other con tent categories, the applicant evaluated the single package with damage from HAC tests, fully flooded, and with full water reflection outside of the package (to satisfy 10 CFR 71.55(b), (d), and (e)). The applicant evaluated the NCT array of 360 packages with the 5-inch pipe op timally moderated with the limited HDPE material, without water flooding, and with full wa ter reflection of the array. The applicant modeled the HAC array of 105 packages (for a CSI of 1.0) or 72 packages (for a CSI of 1.4) with damage from the HAC tests, with varying water dens ity inside the pipe container, package cavity, and outer packaging, varying water density betw een packages, and full water reflection of the array. For the single package models, one (f or 20 wt.% contents) or two (for 10 wt.% contents) pipe containers are modeled centered in the p ackage cavity, as shown in SAR Figure 6.3.4-9. For array models, the applicant evaluated varying off-center configurations of the one or two pipe containers, to move fissile material in adjacent packages closer together

to maximize system keff. The most reactive pipe container array configurations are sh own in SAR Figures 6.3.4-10 and 6.3.4-11 for the dual and single pipe geometries, respectively.

The applicant modeled both homogeneous and heterogeneous config urations of contents withing the 5-inch pipe container. For the homogeneous configu ration, the applicant started with the 5-inch pipe filled with uranium metal, then reduced th e volume in subsequent analyses, first to allow up to the maximum 1.25 lbs. HDPE, then to allow increasing amounts of water. For the heterogeneous configuration, the applicant modeled the fiss ile content as varying size uranium metal spheres, with varying densities of moderator (HDP E and water) in between the particles. The evaluation begins with the particles close pack ed and evaluates increasing pitch for each particle size. The applicant performed heterogeneous evaluations for homogeneous configurations which resulted in system k eff values close to the calculated USL.

The applicants results for the single package case, shown in S AR Table 6.4.4-1, demonstrate that the package remains subcritical for all volume fractions o f fissile content evaluated in the 5-inch pipe container(s). The maximum k eff for the 10 and 20 wt.% contents are significantly below the USL determined for these contents in SAR Section 6.8. Note that the applicant did not perform a specific single package analysis for uranium oxid e contents, as the uranium metal analysis is bounding for the single package.

For the NCT array, the applicants calculated k eff results are shown in SAR Table 6.5.4-1. The maximum system keff for both enrichments considered is with the maximum allowed HD PE content of 1.25 lbs., with no additional water moderator. For both enrichments considered, the maximum NCT array keff is significantly less than the USL determined for these conten ts in SAR Section 6.8. Note that the applicant did not perform a spe cific NCT array analysis for uranium oxide contents, as the uranium metal analysis is boundi ng for the NCT array.

For the HAC array, the applicants calculated k eff results for the homogeneous configuration are shown in SAR Table 6.6.4-1 for 10 and 20 wt.% uranium, and 10 w t.% uranium oxide contents.

While the maximum keff values for the three configurations are still well below the c alculated USL for these contents, the applicant performed a heterogeneous analysis, as heterogeneous systems at low enrichment can potentially be more reactive than homogeneous systems. The heterogeneous analysis results are shown in Table 6.6.4-2 for 1 0 wt.% uranium metal, and in Table 6.6.4-3 for uranium oxide. These results show that heter ogeneous configurations result in a higher keff than homogeneous configurations, but still result in system k eff values that are less than the calculated USL for these contents. The heterogeneous analysis results for 20 wt.%

uranium are shown in SAR Table 6.6.4-4, and show a much smaller increase in keff than for 10 wt.% contents. This is expected, as heterogeneous effects are typically less pronounced as enrichment increases. The applicant performed an additional HA C package flooding study for the 10 wt.% uranium contents, since the k eff results for this content type were closest to the USL. The results of this study, summarized in SAR Table 6.6.4-5, show a small increase in k eff for cases where only the package cavity is flooded with low den sity water, with the maximum keff still remaining below the USL.

In the single package, NCT array, and HAC array analyses, the a pplicant demonstrated that pipe containers with the uranium mass limited only by the volum e of the pipe are subcritical under all conditions. These analyses support the applicants r equest that there be no mass limit for hydrogen limited contents in the 5-inch pipe container, and that the only limit is the volume of the pipe container.

For all analyses of the hydrogen limited 5-inch pipe container in the VP-55, the applicant used the SCALE 6.1.3 code system, with the KENO VI three-dimensional Monte Carlo criticality code

and the continuous-energy ENDF/B-VII.0 cross section library. This is the same code and cross section library used in all other analyses for the Model No. Ve rsa-Pac package. The staffs review of the applicants benchmarking analysis for all configu rations in the package is discussed in Section 6.6 of this SER.

The staff reviewed the applicants calculations for the hydroge n limited contents in 5-inch pipe containers in the VP-55 and agrees that the applicant has ident ified the most reactive configuration for all contents considered. The applicant has s hown and the staff agrees that the Model No. Versa-Pac, with fissile mass of 10 and 20 wt.% enrich ment uranium contents limited by the volume of the 5-inch pipe container, will remain subcrit ical under NCT and HAC in single package and array configurations per the requirements of 10 CFR 71.55 and 10 CFR 71.59.

6.5 Air Transport Mass Limits

The applicant requested to revise the CoC to add or modify air transport mass limits for all content categories. The applicant did not change the previousl y approved analyses that support the air transport mass limits, or the resulting mass limits the mselves. The applicant revised the application to apply the mass limits resulting from the air tra nsport analysis consistently across all content categories.

The previously approved mass limits for air transport are:

• 395 grams for enrichments up to 100 wt.%,

• 495 grams for enrichments up to 20 wt.%,

• 590 grams for enrichments up to 10 wt.%, and

• 790 grams for enrichments up to 5 wt.%.

For the standard configuration with the VP-55 and VP-110, the a pplicant had previously limited the air transport mass limits to those determined for ground tr ansport, since these mass limits are lower. Since this amendment increases the ground transport mass limits for the standard configuration based on updated analyses with new USLs, the air transport mass limits are also increased to be the same as the ground transport limits. These limits are still less than the air transport limits listed above and are therefore conservative.

The only other content category which previously had air transp ort mass limits was the VP-55 with a 5-inch pipe container. These air transport mass limits are requested to remain the same, with the exception that the enrichment mass limits for 5 wt.% e nriched uranium are removed, as discussed in Section 6.3 of this SER. For the hydrogen limited contents in the VP-55, hydrogen limited contents in the VP-55 with 5-inch pipe container, and 1 S/2S uranium hexafluoride (UF6) cylinder contents, air transport mass limits are requested to b e added. The air transport mass limits for these content categories are the lower of the mass l imits determined in the air transport analysis in SAR Section 6.7, or the ground transport limits. This is conservative, since the analysis in SAR Section 6.7 supports the air transport limi ts for all content categories.

The staff reviewed the proposed revised or added air transport limits, and agrees that they are applied in a conservative manner. The applicant has shown and the staff agrees that the Model No. Versa-Pac, with the proposed air transport mass limits disc ussed above, will remain subcritical per the fissile material air transport requirements of 10 CFR 71.55(f).

6.6 Benchmarking Analysis

The applicant revised the benchmark analysis in SAR Section 6.8 to determine enrichment specific USLs for the use of SCALE 6.1.3, with KENO VI and the continuous energy ENDF/B-VII.0 cross section library, to determine k eff for all of the content category models. The analysis in SAR Section 6.8 follows the guidance in NUREG/CR-63 61, Criticality Benchmark Guide for Light-Water-Reactor Fuel in Transportation and Storag e Packages.

The applicant selected 252 critical benchmark experiments from the International Handbook of Criticality Safety Benchmark Experiments, based on qualitative parameters such as fissile and moderating species, structural and reflector material, as well as quantitative parameters such as enrichment, hydrogen to fissile ratio (H/X), and energy of the average neutron lethargy causing fission (EALF). These experiments were selected to cover a wid e range of enrichments and H/X, consistent with the variation of configurations of the Mod el No. Versa-Pac package. For each enrichment range, the applicant determined which of the se lected benchmark experiments were most applicable using the SCALE TSUNAMI sensitivity and un certainty analysis code.

The applicant only used experiments at each enrichment that had a similarity coefficient (ck) of greater than 0.9, indicating that the experiment is highly appl icable to the package configuration being evaluated. For 1.25 wt.% enriched uranium contents, the ck criterion was reduced to 0.85 to ensure there were enough experiments for good validation sta tistics. The staff agrees that this is acceptable, as experiments with c k values 0.8 - 0.9 are considered applicable to the system being evaluated. The only content configuration that re quired addition of experiments outside of the ck range typically considered applicable was the 10 wt.% hydrogen limited contents in two 5-inch pipes. In order to capture the sensitiv ity of this configuration to iron in the steel pipes, additional experiment series with iron present wer e added, and the ck for this configuration was lowered to 0.7 to ensure adequate experiments for validation. The staff agrees that this reduction in c k criteria is acceptable, since the TSUNAMI selection process is an additional step taken to provide a more rigorous experiment sel ection, is not a step recommended in NUREG/CR-6361, and is not used directly in the g eneration of USL equations.

SAR Table 6.8-1 summarizes the critical experiments and their a pplicable qualitative and quantitative selection criteria, and SAR Table 6.8-2 provides t he keff and Monte Carlo uncertainty () values for each experiment, as well as the c k value for each enrichment configuration in the Model No. Versa-Pac package. The applican t used the USLSTATS computer code to generate USL equations for each enrichment con sidered in the package criticality analysis. The USLSTATS code is a generic parameter trending analysis code developed at Oak Ridge National Laboratory that uses the result s of benchmark experiments to estimate code bias and bias uncertainty. This code is a standa rd in the industry for code validation and is acceptable for determining USLs for the packa ge. The applicant also used the USLSTATS code to test keff data for normality. This test indicated that the k eff data were normal for each enrichment evaluated, indicating that the standard val idation statistics recommended in NUREG/CR-6361 can be used.

The resulting USL equations for each enrichment are shown in SA R Table 6.8.2-1, along with the calculated USL. Trending analysis performed by the USLSTAT S code indicated that the trending parameter with the highest correlation coefficient wit h keff for all enrichments was H/X.

Therefore, all the USL equations are based on the H/X trending parameter.

The staff reviewed the applicants revised benchmarking analysi s in SAR Section 6.8. The staff agrees that the enrichment specific USLs are determined in a co nservative manner, consistent with the recommendations of NUREG/CR-6361 and are therefore acc eptable.

The staff reviewed the applicants requested changes to the CoC, initial assumptions, model configurations, analyses, and results. The staff finds that th e applicant has identified the most reactive configurations of the Model No. Versa-Pac package with the requested contents, and that the criticality results are conservative. Therefore, the staff finds with reasonable assurance that the package, with the requested contents, will meet the cr iticality safety requirements of 10 CFR Part 71.

7.0 CONDITIONS

In addition to changes to the content limits and other changes in the CoC, the staff made editorial changes to improve the readability of the CoC. The C oC now includes the following condition(s) of approval:

Condition No. 5(a)(2) was revised to reflect the new revision 4 of drawing VP-55-LD, which includes changes to the drawing notes depicting what packaging components are optional.

Condition No. 5(b)(1) was revised:

- to include a description of the neutron poisons which may be included in the approved contents,

- to include the ability to contain UF 6 sample tubes when in quantities of less than 0.1 kg and to restrict the use of hydrogenous packing materials when s hipping 1S/2S cylinders, except for a polyethylene foam liner, and

- to allow for unlimited use of hydrogenous packing materials u nless otherwise specified (e.g., restricted when shipping 1S/2S cylinders).

Condition No. 5(b)(2) was revised:

- to reflect new mass limits for both ground/vessel and air tra nsport of U-235 (CoC Table 2),

- to reflect new mass limits for U-235 contents with a CSI of 0.7, which also includes these contents at: 5 wt.%, 10 wt.%, and 100 wt.%, (CoC Table 2A),

- to remove the mass limit for U-235 contents at 10 wt.% and le ss for ground/vessel transport in the 5-inch pipe container as the container (CoC Ta ble 3), and

- to define the limits for U-235 contents in the 5-inch pipe wi th limited hydrogenous material (Table 3A).

Condition No. 5(c) was revised to point to CoC Table 3A when ca lculating allowable criticality safety indices for U-235 contents in the 5-inch pipe with limit ed hydrogenous material.

Condition No. 9 was revised to point to the revised licensing d rawing notes to ascertain information about what package components are optional.

The references section has been updated to include reference to this request.

8.0 CONCLUSION

S

Based on the statements and representations contained in the ap plication, as supplemented, and the conditions listed above, the staff concludes that the d esign has been adequately described and evaluated, and the Versa-Pac package meets the re quirements of 10 CFR Part 71.

Issued with Certificate of Compliance No. 9342, Revision No. 16, for the Model No. Versa-Pac.