ML24255A840

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Enclosure 2 - AMNMS-14-0038 Safety Analysis Report - 9975 Packaging
ML24255A840
Person / Time
Site: 07109975
Issue date: 09/16/2014
From:
Office of Nuclear Material Safety and Safeguards
To:
Shared Package
ML24255A837 List:
References
S-SAR-G-00001
Download: ML24255A840 (1)
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Text

Revision 1 S-SAR-G-00001 6-i Safety Analysis Report - 9975 Packaging CHAPTER 6 NUCLEAR CRITICALITY SAFETY EVALUATION Preface This chapter describes the criticality safety evaluation performed for the 9975 package. The content is specified in content envelope C.12 as described in Section 1.2.3 and in Table 1.2. This evaluation demonstrates compliance with the performance requirements of Title 10 of the Code of Federal Regulations (CFR), 10 CFR 71.55 and 71.59[1] for criticality safety.

The analysis demonstrates that the package is subcritical for all single package and array configurations. The package Criticality Safety Index is 0.0.

Revision 1 S-SAR-G-00001 6-ii This Page Intentionally Left Blank

Revision 1 S-SAR-G-00001 6-iii TABLE OF CONTENTS Page 6.1 DISCUSSION AND RESULTS................................................................................................... 6-1 6.2 PACKAGE CONTENT LOADING............................................................................................. 6-3 6.3 MODEL SPECIFICATION........................................................................................................ 6-5 6.3.1 Description of Computational Models................................................................... 6-5 6.3.2 Package Regional Densities................................................................................. 6-16 6.4 CRITICALITY CALCULATIONS............................................................................................ 6-17 6.4.1 Calculational Method........................................................................................... 6-17 6.4.2 Optimal Content Loading..................................................................................... 6-18 6.4.3 Criticality Results................................................................................................. 6-20 6.5 CRITICALITY SAFETY INDEX.............................................................................................. 6-35 6.6 CRITICAL BENCHMARK EXPERIMENTS............................................................................... 6-36 6.6.1 Code Validation and Bias for Pu Oxide Contents................................................ 6-36

6.7 REFERENCES

...................................................................................................................... 6-38 6.8 APPENDICES....................................................................................................................... 6-39

Revision 1 S-SAR-G-00001 6-iv List of Tables Page Table 6.1 - Summary of Criticality Safety Analysis Results...................................................... 6-2 Table 6.2 - Criticality Evaluation Parameters for Package Arrays............................................. 6-3 Table 6.3 - Maximum Fissionable Material Mass....................................................................... 6-4 Table 6.4 - Geometric Specifications for the 9975 Shipping Packages[3]................................... 6-6 Table 6.5 - Drum and Celotex Dimensions for Various Models.............................................. 6-9 Table 6.6 - Types of Convenience Cans and 3013 Containers................................................. 6-10 Table 6.7 - Fire and Drop Test Data for the HAC Model......................................................... 6-16 Table 6.8 - Material Specifications for the 9975 Package and 3013 Containers...................... 6-17 Table 6.9 - Base Case Single Unit Cases Without Flooding..................................................... 6-20 Table 6.10 - Single Unit Cases Flooding the Convenience Can............................................... 6-21 Table 6.11 - Single Unit Cases Flooding the Convenience Can - Beryllium........................... 6-22 Table 6.12 - Single Unit Cases Flooding the Convenience Can - No 3013 Containers........... 6-22 Table 6.13 - Single Unit Cases Flooding the Convenience Can with Beryllium - No 3013.... 6-23 Table 6.14 - Single Unit Cases Flooding the Convenience Can with Carbon.......................... 6-23 Table 6.15 - Single Unit Cases Flooding the PCV, SCV, and Celotex - Inner 3013 Flooded.................................................................................................................. 6-24 Table 6.16 - Single Unit Cases Flooding the PCV, SCV, and Celotex - Outer 3013 Flooded.................................................................................................................. 6-24 Table 6.17 - Single Unit Cases Flooding the PCV, SCV, and Celotex - Both 3013 Containers Flooded................................................................................................ 6-25 Table 6.18 - Single Unit Cases Flooding the PCV, SCV, and Celotex - No 3013 Containers.............................................................................................................. 6-25 Table 6.19 - Filling 5-inch PCV and 6-inch SCV with PuO2 and Flooding Water.................. 6-28 Table 6.20 - Filling 5-inch PCV and 6-inch SCV with PuO2, Beryllium and Flooding Water 6-29 Table 6.21 - Filling 5-inch PCV and 6-inch SCV with PuO2, Carbon and Flooding Water..... 6-30 Table 6.22 - Filling 6-inch SCV with PuO2 - Celotex Flooded............................................. 6-32 Table 6.23 - 9975 Array Model - NCT Cases.......................................................................... 6-33 Table 6.24 - 9975 Array Model - HAC Cases.......................................................................... 6-34 Table 6.25 - 9975 Array Model - Flooded Convenience Can HAC Cases.............................. 6-35 Table 6.26 - CSI Calculation..................................................................................................... 6-36 Table 6.27 - Validation Values, SCALE 5 (KENO-VI), 238-group ENDF/B-V..................... 6-37

Revision 1 S-SAR-G-00001 6-v List of Figures Page Figure 6.1 - Package Schematic................................................................................................ 6-12 Figure 6.2 - 9975 Single Unit with Convenience Can/3013 Combination............................... 6-13 Figure 6.3 - 9975 Single Unit with 6-inch SCV and 5-inch PCV Flooded............................... 6-14 Figure 6.4 - HAC Array (2x2x2) Model, Plan View................................................................ 6-15 Figure 6.5 - 2x2x2, Hypothetical Accident Condition.............................................................. 6-15 Figure 6.6 - 2x2x2 Closest Contact Model (Case 1)................................................................. 6-19 Figure 6.7 - 2x2x2 Symmetrical Model.................................................................................... 6-20 Figure 6.8 - Filling 5-inch PCV and 6-inch SCV with PuO2 and Flooding Water...6-26

Revision 1 S-SAR-G-00001 6-vi Acronyms and Abbreviations CC Convenience Can CFR Code of Federal Regulations CSI Criticality Safety Index HAC Hypothetical Accident Conditions HEU Highly Enriched Uranium MSM Minimum Subcritical Margin NCT Normal Conditions of Transport PCV Primary Containment Vessel SCV Secondary Containment Vessel SS Stainless Steel

Revision 1 S-SAR-G-00001 6-1 6 NUCLEAR CRITICALITY SAFETY EVALUATION 6.1 DISCUSSION AND RESULTS The 9975 package consists primarily of two concentric stainless steel cylindrical containment vessels, a 35-gallon steel drum, Celotex cane and/or softwood fiberboard insulation, aluminum bearing plates, lead shielding body, and aluminum impact absorbers. Fissile material contents, contained within a convenience can, are loaded in the Primary Containment Vessel (PCV) in a 3013 container. The convenience cans facilitate handling, storage and contamination control, but have negligible effect on criticality safety. The criticality analysis includes the reactivity effect of the 3013 container and convenience can. The package is analyzed for the transport of the envelope, identified as C.12 as described in Section 1.2.3. Table 6.1 summarizes the criticality safety results for these contents.

The criticality safety evaluation reported in this Chapter 6 analysis includes the single package analyses required by 10 CFR 71.55 and array analyses for Normal Conditions of Transport (NCT) and Hypothetical Accident Conditions (HAC) required by 10 CFR 71.59. The analysis is performed using the Monte Carlo method as implemented by the CSAS26 sequence of SCALE Version 5.[2]

A spherical shape, considered the most reactive, is not a credible configuration for oxide powder; therefore, a right circular cylinder is conservatively assumed in the analysis described in N-NCS-A-00029 (Reference 3 and Appendix 6.1). These analyses also determined the optimum concentration of hydrogenous media in the insulation region of the shipping package. The HAC model includes radial and axial reduction of drum dimensions due to the accident events, where the amount of damage modeled is based on the results of full-scale drop and fire-event testing of the package.

The base case single unit analysis used a maximum of 5.0 kg plutonium oxide and 0.5% water (to account for moisture content) fissile mixture contained in the convenience can. For the base case, the convenience can and 3013 containers are assumed to be leak tight, thus the fissile material remains dry. Parametric studies were also performed that demonstrate that flooding of the 3013, PCV, and Secondary Containment Vessel (SCV), does not result in a critical configuration.

Table 6.2 summarizes the parameters used in the package array analysis. As required by 10 CFR 71.59, an array of 5N undamaged packages remains subcritical. This NCT condition is satisfied by calculations performed with an infinite (N = ) array of undamaged containers. The HAC analysis results show that an infinite array of damaged packages, loaded with content envelope C.12, is subcritical. This complies with 10 CFR 71.59, which requires that an array of 2N (N = ) containers remains subcritical when subjected to the HAC with optimum moderation and water reflection.

Thus, it was determined that infinite arrays of packages under both NCT and HAC will remain subcritical with a Criticality Safety Index (CSI) equal to 0.0.

Revision 1 S-SAR-G-00001 6-2 The criticality analysis demonstrates that the 9975 package, containing the specified content envelope, is subcritical for all single unit, NCT and HAC cases. This Chapter 6 evaluation complies with the performance requirements of 10 CFR 71.55 and 10 CFR 71.59[1] for criticality safety.

Table 6.1 - Summary of Criticality Safety Analysis Results Content Envelope C.12 Single Unit Results Package calculated to be subcritical under most reactive conditions Max.

keff + 2 = 0.916 (for 9975 flooded condition, Celotex flooded)

Most reactive configuration (right circular cylinder)

SCV/PCV - Filled with Pu water solution (Pu-Oxide Solution, 1.6341 g/cc - 5.025 kg)

Moderation for most reactive configuration Celotex - Fully water flooded Reflection for most reactive configuration (package materials and/or 30 cm water) 30 cm water Array Results NCT Array Max.

keff + 2 = 0.655 Number of packages Infinite Water in drum voids None, dry system Most reactive fissile content Dry Pu Oxide (5.025 kg) in Convenience Can (oxide, 10.8921 g/cc)

Reflection surrounding array Not applicable for infinite array HAC Array Max.

keff + 2 = 0.938 Number of packages Infinite Most reactive fissile content Pu-Oxide Solution in Convenience Can (Pu-Oxide Solution, 3.7421 g/cc - 5.025 kg)

Moderation to credible extent Convenience Can/3013 - Fully water flooded Reflection surrounding array Not applicable for infinite array

Revision 1 S-SAR-G-00001 6-3 Table 6.2 - Criticality Evaluation Parameters for Package Arrays Normal Conditions of Transport (N = )

Number of undamaged packages that remain subcritical in array Infinite Most reactive credible physical and chemical form of fissile material Dry Pu oxide Most reactive interspersed hydrogenous moderation None, dry content Most reactive reflecting material Not applicable for infinite array Reflection surrounding the array Not applicable for infinite array Hypothetical Accident Conditions (N = )

Number of damaged packages to remain subcritical Infinite Most reactive credible physical and chemical form of fissile material Pu-Oxide Solution Most reactive interspersed hydrogenous moderation Convenience Can/3013 - Fully water flooded Most reactive reflecting material Not applicable for infinite array Reflection surrounding the array Not applicable for infinite array

  • Dry means fissile material plus 0.5% water content to account for moisture content.

6.2 PACKAGE CONTENT LOADING Table 1.2, of Chapter 1.0, gives the package content loading limits which is defined as content envelope C.12. The limits presented for radionuclides and impurities apply for both the single unit and array analyses. Contents are right circular plutonium oxide cylinders and have fissionable components as shown in Table 6.3. The base case model analyzed the fissile material as a mixture of plutonium oxide and 0.5% of water to account for moisture content. This evaluation, based on plutonium oxide, also bounds contents with mixtures of plutonium and uranium oxide of the same total mass. This criticality chapter evaluates shipment of plutonium oxide material.

Revision 1 S-SAR-G-00001 6-4 Table 6.3 - Maximum Fissionable Material Mass 1This evaluation, based on 100% 239Pu, also bounds contents with mixtures of plutonium and uranium of the same total mass.

2Although not specified in the content table of Chapter 1.0 of the SAR, these impurities are added to allow for future flexibility.

The content envelope, along with a brief discussion of its modeling, is summarized below.

  • Content Envelope C.12 Plutonium Oxide (5.0 kg Pu Oxide)

This content envelope is predominantly plutonium oxide material, but it may also include impurities (including 500 grams of beryllium, or 1,000 grams of carbon). The total plutonium oxide mass is limited to 5.0 kg (4.4 kg 239Pu). The 5.0 kg is the maximum payload for the shipping package. The addition of the Beryllium or Carbon reduces the fissile content. Hence, the fissile mass decreases as the level of impurities increases.

Material C.121 Pu/U Oxides (grams)

Radioisotope (Radioactive Material Mass) 238Pu n 2.2 239Pu o 4400 240Pu 264 241Pu o, p 50 242Pu 8.8 241Am + 241Pu 50 243Am 1.00 244Cm 0.0044 237Np 220 232U 0.00044 233U o 427 234U q 4400 235U o 4400 236U 2640 238U 4400 232Th 4400 Impurities2 Beryllium (Be) 500 Carbon (C) 1000 Total Mass Radioactive Materials 4400 All Contents 5000

Revision 1 S-SAR-G-00001 6-5 Reactivity decreases when impurities are mixed with fissile materials, mainly due to a reduction in fissile mass and a reduction in fissile mixture density. The analysis models the fissile material in the content envelope conservatively as 100% 239Pu. Beryllium bounds the criticality effects of the other light elements. Therefore, the content envelope is evaluated with 500 grams of beryllium or 1,000 grams of carbon while keeping the total mixture mass at 5.0 kg.

ANSI/ANS-8.1[10] 239Pu limits apply to isotopic mixtures of plutonium provided that the concentration of 240Pu exceeds that of 241Pu and all isotopes are considered to be 239Pu. The package contents meet this restriction. Therefore, content envelope C.12 is conservatively modeled as 100% 239Pu.

6.3 MODEL SPECIFICATION This section presents the computational models used in the criticality analysis for single package and NCT and HAC arrays.

6.3.1 Description of Computational Models The modeled package consists primarily of two concentric stainless steel cylindrical containment vessels (PCV within the SCV), a 35-gallon stainless steel drum, Fiberboard, aluminum plates, lead shield, and aluminum honeycomb spacers. Table 6.4 and Table 6.5 show the modeled dimensions. The SCV is surrounded on the sides and bottom by 0.5 inch of lead shielding.

Fiberboard surrounds the lead shield filling the remainder of the drum. Other components of the package include a 1/2-inch thick aluminum lid covering the lead shield and two 1/2-inch thick aluminum plates, one below the lead shield and one above the aluminum lid. Radioactive material in a convenience can/3013 container configuration is loaded into the PCV. Figure 6.1 shows a schematic of the package.

The base KENO[2] model was developed from the specifications referenced in Table 6.4, which lists the nominal dimensions of various components of the package and the as-modeled dimensions of these components.

The following conservative assumptions were made in developing the criticality models for the base Safety Analysis Report criticality analysis and are maintained in this analysis:

1. Fiberboard insulation. Fiberboard uses a density of 0.20 g/cc although package specifications require a density between 0.22 and 0.26 g/cc. Calculations show that the reactivity of an array of packages increases with decreasing Fiberboard density. Using the lower density is therefore conservative.
2. Drum dimensions. The rolling hoops and the drum lid closure hardware are ignored.

Neglecting these geometric details reduces the effective drum diameter, which in turn conservatively models the array pitch.

3. Lead shield. The thickness of the lead shield was increased to 0.506 inch to include two thin steel liners. The substitution of lead for the stainless steel liner has an insignificant effect on reactivity.

Revision 1 S-SAR-G-00001 6-6

4. Drum and containment vessels. Type 304 stainless steel (SS) was used for the drums and containment vessels in lieu of the 304L SS specified. This material substitution has no effect on the criticality analysis, since composition differences between 304 and 304L SS are negligible based on a sensitivity study in Appendix 1 of N-NCS-A-00029[3].

PCV and SCV dimensions. The ASTM A312 standard[4] has a tolerance of +22.5% / -12.5% on the wall thickness and a tolerance on the outer diameter of +1/16 / -1/32 inch for the PCV and SCV. A sensitivity study[3] was performed on the variation of dimensional tolerances of the PCV and SCV. It was found that there were no statistically significant variations among the keff values calculated with nominal, minimum, and maximum wall thicknesses.

5. Table 6.5 gives the tolerance on drum radius.
6. Thin Steel Liners. The effect of the thin steel liners was ignored as it also has a negligible effect on system reactivity.[3]

Table 6.4 - Geometric Specifications for the 9975 Shipping Packages Component Parameter Specification*

Inch (cm)

KENO Model (cm)

PCV Internal Height 18.63 - 1.88 - 0.37 - 0.258 =

16.122 (40.95 cm) 40.95 PCV Bottom Thickness 0.258 (0.655 cm) 0.655 PCV Top Thickness 1.88 - 0.5 = 1.38 (3.505 cm) 3.505 PCV Top Nut Height (top portion) 0.5 (1.27 cm) 1.270 PCV Skirt Height 0.37 (0.94 cm) 0.94 PCV Inner Radius 5.047*0.5 (6.410 cm) 6.410 PCV Outer Radius 5.563*0.5 (7.065 cm) 7.065 SCV Top Aluminum Spacer Height 1.80 (4.572 cm) 4.572 SCV Void Space Height 24.0 - 1.88 - 0.38 - 0.28-1.0 -

18.63 + 0.5 - 1.8 = 0.53 (1.35 cm) 1.35 SCV Top Thickness 1.88 - 0.5 = 1.38 (3.505 cm) 3.505 SCV Top Nut Height (top portion) 0.5 (1.27 cm) 1.27

Revision 1 S-SAR-G-00001 6-7 Component Parameter Specification*

Inch (cm)

KENO Model (cm)

SCV Bottom Aluminum Honeycomb Spacer Height 1.0 (2.54 cm) 2.54 SCV Bottom Thickness 0.28 (0.711 cm) 0.711 SCV Skirt Height 0.38 (0.965 cm) 0.965 SCV Inner Radius 6.065*0.5 (7.7026 cm) 7.703 SCV Outer Radius 6.625*0.5 (8.414 cm) 8.414 SCV Spacer Inner/Outer Radius 3.7*0.5/5.8*0.5 (4.699/7.366 cm) 4.699/7.366 Drum Inner Radius (18.25 +/- 0.06)*0.5 18.19 *0.5, min

= 9.095 (23.101 cm) 21.466 (calculated NCT value)

Drum Outer Radius (23.101 + 0.122) cm (23.223 cm) 23.223*.93

=21.597 (NCT Value)

Drum Top Void Thickness (nominal) 34.75 - 33.90 = 0.85 (2.16 cm) 2.16 Drum Top Wall Thickness 0.048 (0.122 cm) 0.122 Drum Bottom Void Thickness 0

(0 cm) 0 Drum Bottom Wall Thickness 0.048 (0.122 cm) 0.122 Drum Top Wall Thickness 0.048 (0.122 cm) 0.122 Aluminum Lid for Lead Shield Thickness 0.5 (1.27 cm) 1.27 Drum Inner Height 34.75 (88.265 cm)

Used to calculate top void thickness in drum Lead Shield Thickness 0.506, min (1.285 cm)

(including 0.036 SS304 liner) 1.285

Revision 1 S-SAR-G-00001 6-8 Component Parameter Specification*

Inch (cm)

KENO Model (cm)

Lead Shield Inner Radius 7.25*0.5 = 3.625 (9.208 cm) 9.208 Lead Shield Outer Radius 3.625+0.506 = 4.131 (10.493 cm) 10.493 Aluminum Plate Outer Radius 5.6 (14.224 cm) 14.224 Aluminum Bearing Plate, Top Height 0.5 (1.27 cm) 1.27 Aluminum Bearing Plate, Bottom Height 0.5 (1.27 cm) 1.27 Fiberboard Top Thickness 3.7 (9.398 cm) 9.398 Fiberboard Bottom Thickness 3.8 (9.652cm) 9.652 Fiberboard Outer Radius 18.1*0.5 = 9.05 (22.987 cm) 22.987 (Single Unit Model) 21.466 (NCT Model)

(used 21.466 to match inner diameter of drum)

  • Dimensions are established in N-NCS-A-00029[3], which is the basis for the 9975 shipping package models in this document. See Reference 3 for details.

Revision 1 S-SAR-G-00001 6-9 Table 6.5 - Drum and Celotex Dimensions for Various Models Feature Specification (cm)

Single Package Model (cm)

NCT Array Model (cm)

HAC Array Model (cm)

Drum Outer Radius 23.101+0.122

23.223 cm 23.101 + 0.122

23.223 23.223 x 0.93 =

21.597 19.235

[(23.223 - 2.54) x 0.93]

Note:

1.0 in. (2.54 cm) drum radial reduction due to impact (see Table 6.8).

Drum Wall Thickness (0.048 inch) 0.122 cm 0.122 0.131 (0.122 cm thickness changed to 0.131 cm to conserve mass of drum wall) 0.147 Drum Inner Radius (18.25+/- 0.06)*0.5 inches (23.101 cm) 23.101 21.597 - 0.131 =

21.466 19.088 Fiberboard Outer Radius 18.1*0.5

9.05 inches 22.987 cm 22.987 21.466 matches drum inner diameter 22.987 - 6.35

16.637 Note:

2.5 in. (6.35 cm)

Celotex loss due to fire (see Table 6.8).

Nominal package component dimensions (except the drum diameter) were used since the dimensional tolerances are small and their effects on reactivity were judged to be insignificant.

A lower tolerance value was used for the drum diameter to conservatively estimate the array pitch and, thus, to maximize the interaction effect among the fissile material in different packages. In this analysis, the two rolling hoops and bolted ring closure of the drum were neglected. Neglecting these geometric details reduces the effective drum diameter, which in turn, conservatively models the array pitch.

Model 3013 and Convenience Can A convenience can is used to contain the fissile material. The convenience can is housed in the 3013 containers of the 9975 during transport. The 3013 container consists of two nested and sealed containers (inner and outer) that isolate the fissile material. The 3013 containers and the convenience cans are fabricated of stainless steel. Table 6.6 lists three types of convenience cans with their associated 3013 containers, along with their dimensions, used for shipment of oxide powder.

Table 6.6 also shows the bounding dimensions for the reference convenience can and 3013 containers developed for the KENO model. The KENO model used in this analysis has

Revision 1 S-SAR-G-00001 6-10 dimensions consistent with the volume of the Rocky Flats configuration due to its slightly larger volume.

Table 6.6 - Types of Convenience Cans and 3013 Containers Parameter Nominal Dimensions (cm)

Rocky Flats Hanford SRS Reference Dimension for KENO Model Convenience Can Outer Diameter 11.00 10.85 11.16 11.00 Outer Diameter -

Inner Diameter Difference 0.05 0.31 0.21 0.05 Top Lid /Bottom Thickness 0.025/

0.025 0.305/

0.635 0.163/

0.152 0.025/

0.025 External Height 20.75 20.40 18.80 20.75 Internal Height 20.70 19.46 18.48 20.70 Material SS 316 SS 304/304L SS 304/304L Reference M-PV-F-0015 R-R4-F-0144 R-R1-F-0098 Inner Can Outer Diameter 11.35 11.68 11.16 11.35 Outer Diameter -

Inner Diameter Difference 0.30 0.30 0.21 0.30 Top Lid /Bottom Thickness 0.20/0.15 0.152/0.635 0.163/152 0.20/0.15 External Height 23.10 22.00 18.80 23.10 Inner Height 22.75 21.21 18.48 22.75 Material SS 316 SS 304L SS 304L Reference M-PV-F-0016 R-R4-F-0107 R-R4-F-0107 Outer Can Outer Diameter 12.51 12.51 12.51 12.51 Outer Diameter -

Inner Diameter Difference 0.62 0.62 0.62 0.614 Top Lid /Bottom Thickness 1.91/0.90 1.91/0.90 1.91/0.90 1.91/0.90 External Height 25.40 25.40 25.40 25.40 Internal Height 23.40 23.40 23.40 24.11 Material SS 316 SS 316 SS 316 Reference M-PV-F-0017 M-PV-F-0017 M-PV-F-0017 M-PV-F-0017 M-PV-F-0017 M-PV-F-0017

Revision 1 S-SAR-G-00001 6-11 6.3.1.1 Single Package Models 10 CFR 71.55 requires single unit analysis to account for the most reactive configurations, including moderation by water to the most reactive credible extent. Therefore, to simulate water inleakage, subsequent variations of the base case modeled water flooding into the convenience can and ultimately filling it while keeping the amount of fissile material constant. This parametric study included variations of water flooding into the 3013, PCV, and SCV.

Figure 6.1 shows a schematic of the 9975 shipping package (convenience can/3013 containers not shown), and Figure 6.2 shows the corresponding KENO model. The 9975 drum overall size is about 34 inches in height and 18 inches in diameter. The base case model analyzed the fissile material as a mixture of plutonium oxide and 0.5% of water to account for moisture content. The fissile material is configured as a right circular cylinder, inside a convenience can, with a height/diameter ratio equal to 1 to maximize reactivity since formation of a spherical configuration is not credible for oxide material. This base case 9975 model assumed no additional water or flooding with the 3013, PCV, and SCV remaining dry.

Revision 1 S-SAR-G-00001 6-12 24 4.85 5.6 7.25 Outer Wall Thickness =

0.048 11.2 18.1 8.26 2.50 23.62 2.50 18.26 6.065 5.047 Celotex Stainless Steel Aluminum Lead All dimensions in inches (Not to Scale) 18.29 Figure 6.1 - Package Schematic

Revision 1 S-SAR-G-00001 6-13 Figure 6.2 - 9975 Single Unit with Convenience Can/3013 Combination The convenience can or 3013 containers are not considered a containment boundary; therefore, subsequent variations of the base case model removed the convenience can or 3013 containers.

The first series of cases will have the PCV containing a mixture of water and plutonium oxide.

As water enters the PCV, a plutonium oxide solution is created with water reflection above the solution, until the entire volume of the PCV is filled. As the plutonium oxide-water mixture volume increases, the water reflection above the mixture decreases, and the space between the SCV and the stainless steel of the PCV is initially filled with water.

These cases were modeled with the SCV and PCV in position containing water or plutonium oxide solution, removing the stainless steel of the convenience can and 3013 containers. The stainless steel PCV, being credited as a containment boundary, will remain in the SCV because it is not credible for the PCV to be absent from the shipping package. However, all aluminum within the SCV, which has minimal neutronic impact on criticality, has been replaced with either water or fissile solution, depending on the case being evaluated.

The next series of cases has the primary containment vessel and secondary containment vessel both containing a plutonium oxide solution. Thus, as water is added to the shipping package, the plutonium oxide-water solution will fill the total volume (height and diameter) of the SCV, minus the space occupied by the steel of the PCV, keeping the fissile mass constant. Thus, as the PCV fills with fissile solution, the spillage fills the gap between the SCV and the stainless steel of the PCV (Figure 6.3). As the plutonium oxide-water mixture volume increases, the water reflection around or above the mixture decreases, by simple replacement. This parametric study is illustrated in Figure 6.3 as a cylinder of plutonium oxide-water mixture (magenta), filling the SCV (cyan) and PCV (cyan). For this single package analysis, the outer container (drum) was reflected with 30 cm of water on all sides (yellow).

Revision 1 S-SAR-G-00001 6-14 Figure 6.3 - 9975 Single Unit with 6-inch SCV and 5-inch PCV Flooded 6.3.1.2 NCT Array Model 10 CFR 71.55 requires the NCT analysis to address undamaged packages in an array. Therefore, for the NCT model, an infinite array of undamaged 9975 shipping packages was analyzed with the convenience can containing the plutonium oxide, in dry conditions (the 0.5% water for moisture content is included as dry conditions). This model is similar to the base case single unit model but with an infinite array of 9975 drums containing fissile material.

In the infinite models, there is no leakage from the system (the 3013, PCV, and SCV remain dry), and reflection is irrelevant. Thus, a single 9975 package was modeled inside a tight fitting cuboid with mirror boundary conditions defined for the four x and y faces. In addition, periodic boundary conditions were defined for the z faces of the cuboid using standard KENO options.

These boundary conditions reflected all incident neutrons back into the system thus simulating an infinite square pitch array of packages.

Although the NCT analysis evaluates undamaged packages, cases were analyzed to account for water being present in the Celotex.

6.3.1.3 HAC Array Model The HAC model is required per 10 CFR 71.55 to address the most credible configuration of damaged packages, thus this analysis used an infinite array modeled as an infinite array of 2x2x2 clusters of damaged 9975 packages. The infinite array was modeled inside a tight fitting cuboid with mirror boundary conditions defined for the four x and y faces. In addition, periodic boundary conditions were defined for the z faces of the cuboid using standard KENO options

Revision 1 S-SAR-G-00001 6-15 The damaged HAC array model used conservative assumptions regarding the radial and axial reduction of drum dimensions to address a drop and the amount of Celotex charred due to fire, as shown in Table 6.7. Additional reduction factors were added to the burn and drop test data for conservatism, also shown in Table 6.7. As previously stated and as documented in N-NCS-A-00029, Appendix 1[3], Celotex inhibits neutronic interaction between packages and removing the outer layers of Celotex increases the keff for array calculations; thus, modeling less Celotex is conservative.

To address the fissile units at close contact, a conservative, although not credible, HAC model is constructed by assuming maximum movement of the inner containment vessels (Figure 6.4).

The Celotex has also moved and is off-center. The fissile material is in the dry configuration of the single unit base case model, which is contained in the volume of the convenience can, as shown in Figure 6.5.

Figure 6.4 - HAC Array (2x2x2) Model, Plan View Figure 6.5 - 2x2x2, Hypothetical Accident Condition

Revision 1 S-SAR-G-00001 6-16 Table 6.7 - Fire and Drop Test Data for the HAC Model Dimension Celotex Burn Test Data*

(in.)

HAC Model (in.)

Drop Test Data*

(in.)

HAC Model (in.)

Radial 2.3 2.5 1.0 1.0 Axial (top/bottom) 1.4/2.0 2.0/2.0 1-1/8 (total) 1.0/1.0 Reference WSRC-SA-7, Revision 14, Safety Analysis Report Packages 9965, 9968, 9972 -

9975 Packages (U),

Appendix 3.7, Thermal Test.

WSRC-SA-7, Chapter 2.0.

  • See ASTM A312[4] for details.

6.3.2 Package Regional Densities The convenience can, 3013 containers, PCV, SCV, and the drum are made of 304L or 316 stainless steel. However, the analysis used a standard stainless steel, SS 304 with a density of 7.92 g/cc. The small difference in composition between SS 304, SS 304L, and SS 316 will have a negligible effect on reactivity (Appendix 1 of N-NCS-A-00029[3]).

As described in N-NCS-A-00029[3] Appendix 1, Celotex insulation with a nominal density of 0.22 to 0.26 g/cc has the elemental composition of cellulose (C6H10O5) and can absorb about 31% by weight of water when the drum is flooded. In addition, it was shown that keff increases as the Celotex density is decreased. Thus, to account for void spaces between layers, this analysis will use a Celotex density of 0.20 g/cc.

Water density is conservatively taken as 1.0 g/cc instead of a nominal value of 0.9982 g/cc at 20ºC, to cover temperatures as low as 0ºC.

Aluminum honeycomb spacer density is selected as 0.28 g/cc. Any variation of the aluminum honeycomb spacer density will have negligible effect on the system reactivity.

The 9975 material data in Table 6.8 is described in N-NCS-A-00029[3].

Revision 1 S-SAR-G-00001 6-17 Table 6.8 - Material Specifications for the 9975 Package and 3013 Containers Components Material Density (g/cc) (as-modeled)

Water H2O 0.9982 at 20°C 0.99998 at 4°C (used 1.0 g/cc)

PCV and SCV 304L SS (used SS 304) 7.92 Drum 304L SS (used SS 304) 7.92 Aluminum Lid and Plates Aluminum 2.70 Lead Shield Lead 11.34 Celotex C6H10O5 14 - 16 lb/ft3 (0.22 - 0.26 g/cc)

(used 0.20 g/cc)

Polyethylene C2H4 0.92 (used 0.95 g/cc)

PVC C2H3Cl 0.95 Fissile Content a PuO2 See Table 6.1 a Plutonium is modeled as 239Pu.

6.4 CRITICALITY CALCULATIONS This section describes the calculation methods and the optimal content loading for the plutonium oxide contents.

6.4.1 Calculational Method This study used the SCALE 5 code system[2], operating on the SRNS Criticality Safety Advanced Computing Center, to calculate keff values. The SCALE system is under configuration control, SRNS-RP-2008-00150[5] and SRNS-RP-2008-00151[6]. The CSAS26 driver was used.

It calls the BONAMI and CENTRM modules for the generation of a problem-dependent cross sections library (accounting for resonance self-shielding) and then calls the KENO-VI module to perform the Monte Carlo keff calculations. All calculations used the 238-group ENDF/B-V cross section set, ORNL/TM-12370[8]. Calculations were performed using numbers of generations and neutrons per generation to achieve a calculated statistical uncertainty () less than 0.002.

The calculated value of keff must be less than the value of ksafe, where ksafe includes a subcritical margin, the system bias, and uncertainties in that bias. The reported values of keff are the calculated values plus 2 standard deviations. SCALE 5 has been certified on the SRNS computing system in accordance with approved quality assurance procedures.

Revision 1 S-SAR-G-00001 6-18 6.4.2 Optimal Content Loading 6.4.2.1 Single Package Analyses The single package analyses consider the fissile material in a dry and a flooded convenience can.

The single unit base case model was developed with a maximum of 5.0 kg plutonium oxide and 0.5% water fissile mixture contained in the convenience can. The convenience can and 3013 containers are assumed to be leak tight, thus the fissile material remains dry. Cases were modeled with and without the 3013 container. Table 6.9 summarizes the resultant keff values.

Figure 6.2 shows the fissile material and convenience can/3013 combination in the 9975 shipping package.

To address damage to the convenience can and flooding, a parametric study was performed filling the convenience can with water while maintaining the fissile material constant at 5.0 kg plutonium oxide. The height/diameter ratio is equal to 1 to maximize reactivity until the fissile cylinder fills the diameter of the inner container. Then the height of the cylinder will be increased until the inner container is full. Therefore, the fissile solution fills the entire width of the convenience can and the water level is varied.

To address damage to the convenience can and 3013 containers with water flooding into the PCV and SCV, single package models were created filling the 6-inch SCV and 5-inch PCV with water, creating a fissile solution. The fissile mass remains constant at 5.0 kg plutonium oxide as water is added. Thus, convenience can and 3013 containers that are internal to the PCV are removed. In addition, the volumes occupied by the aluminum spacers and aluminum absorbers will be assumed as volumes available to be filled with water and solution. Therefore, the maximum usable volumes (using the volumes occupied by the non-stainless material inside the SCV and PCV) were used.

Removing the convenience can, the 3013 containers and all aluminum material in the SCV is conservative in that the steel would have separated the fissile solution, absorbed neutrons, and occupied space resulting in less fissile solution. In addition, the volume of the aluminum spacers and absorbers within the SCV, which have minimal neutronic impact, would occupy space also resulting in less fissile solution.

This parametric study was performed with water entering the 9975 shipping package with the aluminum, convenience can, and 3013 containers removed. The result is a plutonium oxide and water in the PCV, which creates a plutonium oxide solution while maintaining the fissile mass constant at 5.0 kg plutonium oxide. As the water starts to mix with the plutonium oxide, the volume of the plutonium oxide solution will increase and fill the diameter and height of the PCV.

At this point, the volume between the SCV and PCV is filled with water.

After the PCV fills to maximum height with plutonium oxide solution, the fissile solution spills into the SCV, until the SCV is completely full.

Revision 1 S-SAR-G-00001 6-19 6.4.2.2 NCT Array Analyses In the NCT undamaged drum array modeled, as analyzed in N-NCS-A-00029[3], no water enters the PCV, 3013, or convenience can. Thus, an infinite array of drums was analyzed with the convenience can containing dry plutonium oxide and 0.5% water fissile mixture, with or without the 3013 containers and additional cases with the Celotex flooded. As mentioned earlier, all NCT array analyses were performed using the 7% reduced drum radius to utilize an equivalent rectangular array configuration.

6.4.2.3 HAC Array Analyses In the HAC analysis, damaged units are arranged in various configurations to demonstrate a most reactive configuration. A conservative infinite array modeled as an infinite array of 2x2x2 clusters was developed where the fissile material was moved together as close as possible. This model brought a cluster of four drums, stacked two high (eight packages total), to its closest contact position. In other words, the radial movement is such that four drums together form the closest configuration (a quadrupole arrangement), as shown in Figure 6.6.

Figure 6.6 - 2x2x2 Closest Contact Model (Case 1)

These models assume that the Celotex loss is localized around the periphery of the drum, and the 9975 is dropped during the accident. The inner containment (convenience can/3013/PCV/SCV) is moved inside the Celotex (keeping the Celotex volume constant) such that the lead shield is touching the drum at one point.

Although the close contact HAC model (Figure 6.6, Table 6.24 - Case 1) minimizes fissile spacing between the payloads in as many as eight packages, it increases fissile spacing between those packages and the packages surrounding them. Thus, it is not entirely obvious that a HAC model that only accounts for the destruction of Celotex but includes none of the material movements, is less reactive or not. Therefore, an additional symmetrical model was also developed (Figure 6.7, Table 6.24 - Case 5) to help determine the most reactive configuration.

Table 6.24 - Case 5 (symmetrical model) is a damaged array scenario with the Celotex, containment, and fissile material in its normal, centered orientation, but the destruction of Celotex due to fire and reduction of drum diameter due to impact are included.

Revision 1 S-SAR-G-00001 6-20 Figure 6.7 - 2x2x2 Symmetrical Model 6.4.3 Criticality Results Section 6.4.3.1 discusses the single package results. Section 6.4.3.2 discusses the NCT array results and Section 6.4.3.3 discusses the HAC array results. The input and output files associated with the cases discussed in these sections are listed in Appendix 6.2 and included on a CD.

6.4.3.1 Single Package Results 6.4.3.1.1 Convenience Can Intact As seen in Table 6.9, the base case (Case 1) with a convenience can containing dry plutonium oxide, with the 3013 containers in place, yields a maximum keff value of 0.595. In addition, Table 6.9 shows that the addition of 500 grams of beryllium or 1000 grams of carbon does not cause an increase in keff above the base case with dry plutonium oxide in an intact convenience can/3013 configuration (Table 6.9, Case 1).

Table 6.9 - Base Case Single Unit Cases Without Flooding Case No.

File ID Description keff keff +2

1. nrc_su.cyl3013.out:

Base Case with 3013, dry oxide 0.5922 0.0010 0.595

2. nrc_su.cyl3013be.out:

Base Case with 3013 and mixed with beryllium, dry oxide 0.4805 0.0009 0.483

3. nrc_su.cylno3013.out:

Base Case with no 3013, dry oxide 0.5796 0.0010 0.582

4. nrc_su.cylno3013be.out:

Base Case with no 3013 and mixed with beryllium, dry oxide 0.4669 0.0009 0.469

5. nrc_su.cyl3013c12.out:

Base Case with 3013 and mixed with carbon, dry oxide 0.3880 0.0007 0.390

Revision 1 S-SAR-G-00001 6-21 6.4.3.1.2 Convenience Can Damaged Tables 6.10 through 6.14 compare the keff values for a single unit to examine the effects of flooding the convenience can while forming a homogenized solution, with or without the 3013 container in place. As shown in Table 6.10, the highest keff of 0.629 is achieved when the convenience can is completely full of fissile solution (plutonium oxide plus flooding water) in a convenience can/3013 combination (Table 6.10, Case 11).

Table 6.10 - Single Unit Cases Flooding the Convenience Can Case No.

File ID Description keff keff +2

1. nrc_su.cyl3013_100.out:

Base Case with 3013, dry oxide - 0.1 liter water added 0.5602 0.0010 0.563

2. nrc_su.cyl3013_200.out:

Same as #1 - 0.2 liter water added 0.5513 0.0010 0.554

3. nrc_su.cyl3013_300.out:

Same as #1 - 0.3 liter water added 0.5541 0.0010 0.557

4. nrc_su.cyl3013_400.out:

Same as #1 - 0.4 liter water added 0.5637 0.0010 0.566

5. nrc_su.cyl3013_400w.out:

Same as #1 - 0.4 liter water added, diameter of convenience can (CC) 0.5657 0.0010 0.568

6. nrc_su.cyl3013_500w.out:

Same as #5 - 0.5 liter water added 0.5692 0.0011 0.572

7. nrc_su.cyl3013_750w.out:

Same as #5 - 0.75 liter water added 0.5897 0.0013 0.593

8. nrc_su.cyl3013_1000w.out:

Same as #5 - 1.0 liter water added 0.6017 0.0011 0.604

9. nrc_su.cyl3013_1100w.out:

Same as #5 - 1.1 liters water added 0.6062 0.0012 0.609

10. nrc_su.cyl3013_1200w.out:

Same as #5 - 1.2 liters water added 0.6098 0.0011 0.612

11. nrc_su.cyl3013_ccfull.out Same as #5 CC full 0.6260 0.0013 0.629

Revision 1 S-SAR-G-00001 6-22 Table 6.11 - Single Unit Cases Flooding the Convenience Can - Beryllium Case No.

File ID Description keff keff +2

1. nrc_su.cyl3013be_100.out:

Base Case with 3013 and mixed with beryllium, dry oxide - 0.1 liter water added 0.4770 0.0010 0.479

2. nrc_su.cyl3013be_200.out:

Same as #1 - 0.2 liter water added 0.4888 0.0010 0.491

3. nrc_su.cyl3013be_200w.out:

Same as #1 - 0.2 liter water added, diameter of CC 0.4891 0.0009 0.491

4. nrc_su.cyl3013be_300w.out:

Same as #3 - 0.3 liter water added 0.5009 0.0011 0.504

5. nrc_su.cyl3013be_500w.out:

Same as #3 - 0.5 liter water added 0.5228 0.0012 0.526

6. nrc_su.cyl3013be_750w.out:

Same as #3 - 0.75 liter water added 0.5448 0.0012 0.548

7. nrc_su.cyl3013be_1000w.out Same as #3 - 1.0 liter water added 0.5586 0.0011 0.561
8. nrc_su.cyl3013be_1100w.out:

Same as #3 - CC full 0.5670 0.0013 0.570 Table 6.12 - Single Unit Cases Flooding the Convenience Can - No 3013 Containers Case No.

File ID Description keff keff +2

1. nrc_su.cylno3013_100.out:

Base Case with no 3013, dry oxide -

0.1 liter water added 0.5470 0.0010 0.549

2. nrc_su.cylno3013_200.out:

Same as #1 - 0.2 liter water added 0.5338 0.0010 0.536

3. nrc_su.cylno3013_300.out:

Same as #1 - 0.3 liter water added 0.5348 0.0009 0.537

4. nrc_su.cylno3013_400.out:

Same as #1 - 0.4 liter water added 0.5418 0.0011 0.544

5. nrc_su.cylno3013_400w.out:

Same as #1 - 0.4 liter water added, diameter of CC 0.5391 0.0012 0.542

6. nrc_su.cylno3013_500w.out:

Same as #5 - 0.5 liter water added 0.5493 0.0010 0.552

7. nrc_su.cylno3013_750w.out:

Same as #5 - 0.75 liter water added 0.5618 0.0012 0.565

8. nrc_su.cylno3013_1000w.out:

Same as #5 - 1.0 liter water added 0.5717 0.0012 0.575

9. nrc_su.cylno3013_1100w.out:

Same as #5 - 1.1 liters water added 0.5782 0.0012 0.581

10. nrc_su.cylno3013_1200w.out:

Same as #5 - 1.2 liters water added 0.5790 0.0011 0.582

11. nrc_su.cylno3013_1300w.out:

Same as #5 - 1.3 liters water added 0.5870 0.0011 0.59

12. nrc_su.cylno3013_ccfull.out Same as #5 - CC full 0.6190 0.0012 0.622

Revision 1 S-SAR-G-00001 6-23 Table 6.13 - Single Unit Cases Flooding the Convenience Can with Beryllium - No 3013 Case No.

File ID Description keff keff +2

1. nrc_su.cylno3013be_100.out:

Base Case with no 3013 and mixed with beryllium, dry oxide - 0.1 liter water added 0.4632 0.0009 0.465

2. nrc_su.cylno3013be_200.out:

Same as #1 - 0.2 liter water added 0.4685 0.0010 0.471

3. nrc_su.cylno3013be_200w.out:

Same as #1 - 0.2 liter water added, diameter of CC 0.4695 0.0009 0.472

4. nrc_su.cylno3013be_300w.out:

Same as #3 - 0.3 liter water added 0.4795 0.0010 0.482

5. nrc_su.cylno3013be_500w.out:

Same as #3 - 0.5 liter water added 0.4959 0.0011 0.499

6. nrc_su.cylno3013be_750w.out:

Same as #3 - 0.75 liter water added 0.5172 0.0012 0.520

7. nrc_su.cylno3013be_1000w.out:

Same as #3 - 1.0 liter water added 0.5320 0.0010 0.534

8. nrc_su.cylno3013be_1100w.out:

Same as #3 - CC full 0.5375 0.0012 0.540 Table 6.14 - Single Unit Cases Flooding the Convenience Can with Carbon Case No.

File ID Description keff keff +2

1. nrc_su.cyl3013c12_100.out:

Base Case with 3013 and mixed with carbon, dry oxide - 0.1 liter water added 0.4033 0.0009 0.406

2. nrc_su.cyl3013c12_100w.out:

Same as #1 - 0.1 liter water added, diameter of CC 0.4003 0.0009 0.402

3. nrc_su.cyl3013c12_200w.out:

Same as #2 - 0.2 liter water added 0.4093 0.0009 0.412

4. nrc_su.cyl3013c12_300w.out:

Same as #2 - 0.3 liter water added 0.4227 0.0010 0.425

5. nrc_su.cyl3013c12_400w.out:

Same as #2 - 0.4 liter water added 0.4406 0.0010 0.443

6. nrc_su.cyl3013c12_500w.out:

Same as #2 - 0.5 liter water added 0.4549 0.0014 0.458

7. nrc_su.cyl3013c12_750w.out:

Same as #2 - 0.75 liter water added 0.4786 0.0012 0.481

8. nrc_su.cyl3013c12_1000w.out:

Same as #2 - 1.0 liter water added 0.5012 0.0011 0.504

Revision 1 S-SAR-G-00001 6-24 Based on Tables 6.10 through 6.14, the most reactive cases are achieved with the convenience cans fully flooded with plutonium oxide solution. Thus, additional cases were run varying water flooding into the various compartments (PCV, SCV, Celotex) of the 9975 shipping package.

Tables 6.15 through 6.18 list this comparison.

Table 6.15 - Single Unit Cases Flooding the PCV, SCV, and Celotex - Inner 3013 Flooded Case No.

File ID Description keff keff +2

1. nrc_su.cyl3013_ccfull_3013inn.out:

CC - full of solution 3013 - inner flooded with water 0.6598 0.0014 0.663

2. nrc_su.cyl3013_ccfull_3013inner_PCV.out:

Same as #1 - PCV contains water 0.6633 0.0013 0.666

3. nrc_su.cyl3013_ccfull_3013inner_PCVSCV.out Same as #1 -

PCV/SCV contains water 0.6979 0.0012 0.701

4. nrc_su.cyl3013_ccfull_3013inner_SCV.out:

Same as #1 - SCV contains water 0.6849 0.0012 0.688 Table 6.16 - Single Unit Cases Flooding the PCV, SCV, and Celotex - Outer 3013 Flooded Case No.

File ID Description keff keff +2

1. nrc_su.cyl3013_ccfull_3013outer.out:

CC - full of solution 3013 - outer flooded with water 0.6352 0.0013 0.638

2. nrc_su.cyl3013_ccfull_3013outer_PCV.out:

Same as #1 - PCV contains water 0.6490 0.0013 0.652

3. nrc_su.cyl3013_ccfull_3013outer_PCVSCV.out Same as #1 -

PCV/SCV contains water 0.6782 0.0013 0.681

4. nrc_su.cyl3013_ccfull_3013outer_SCV.out:

Same as #1 - SCV contains water 0.6654 0.0014 0.669

Revision 1 S-SAR-G-00001 6-25 Table 6.17 - Single Unit Cases Flooding the PCV, SCV, and Celotex - Both 3013 Containers Flooded Case No.

File ID Description keff keff +2

1. nrc_su.cyl3013_ccfull_3013both.out:

CC - full of solution 3013 - inner/outer flooded with water 0.6693 0.0013 0.672

2. nrc_su.cyl3013_ccfull_3013both_PCV.out:

Same as #1 - PCV contains water 0.6834 0.0014 0.687

3. nrc_su.cyl3013_ccfull_3013both_PCVSCV.out:

Same as #1 -

PCV/SCV contains water 0.7049 0.0014 0.708

4. nrc_su.cyl3013_ccfull_3013both_SCV.out:

Same as #1 -SCV contains water 0.6920 0.0012 0.695

5. nrc_su.cyl3013_ccfull_3013both_PCV_Celo.out:

Same as #1 - PCV/

Celotex as water 0.7158 0.0013 0.719

6. nrc_su.cyl3013_ccfull_3013both_ALL.out:

Same as #1 -

PCV/SCV/

Celotex as water 0.7325 0.0015 0.736 Table 6.18 - Single Unit Cases Flooding the PCV, SCV, and Celotex - No 3013 Containers Case No.

File ID Description keff keff +2

1. nrc_su.cylno3013_ccfull.out:

CC - full of solution No 3013 0.6204 0.0012 0.623

2. nrc_su.cylno3013_ccfull_PCV.out:

Same as #1 - PCV contains water 0.6847 0.0015 0.688

3. nrc_su.cylno3013_ccfull_PCVSCV.out:

Same as #1 - PCV/SCV contains water 0.7097 0.0013 0.713

4. nrc_su.cylno3013_ccfull_SCV.out:

Same as #1 -SCV contains water 0.6219 0.0015 0.625

5. nrc_su.cylno3013_ccfull_PCVSCV_ALL.out:

Same as #1 - PCV/SCV/

Celotex as water 0.7353 0.0013 0.738 Tables 6.15 through 6.18 show that a 9975 shipping package with a convenience can containing plutonium oxide solution, with or without the 3013 container, with water flooding in all compartments of the 9975 shipping package is subcritical. The highest keff + 2 of 0.738 was achieved for the case with a homogenized fissile cylinder modeled the width of the convenience can, no 3013 containers, with the PCV, SCV, and Celotex regions fully flooded with water (Table 6.18, Case 5).

Revision 1 S-SAR-G-00001 6-26 6.4.3.1.3 Damaged Containment and Flooding 6-inch SCV To address failure of the convenience can and 3013 containers, analyses were performed filling the PCV and SCV with plutonium oxide solution. Figure 6.8 and Table 6.19 through Table 6.21, show that plutonium oxide mixed with water in the PCV and SCV remains subcritical as the added water causes the density of the solution to decrease by holding the mass of the plutonium oxide constant. All cases in Table 6.19 through Table 6.21 initially have water mixing with the plutonium oxide in the shipping package, creating a plutonium oxide solution in the PCV and water only in the SCV. As the PCV fills with solution, spillage fills the SCV until totally full with the plutonium oxide solution.

As shown in Figure 6.8, the results without the symbols indicate the PCV filling with plutonium oxide solution until full, with water in the volume between the SCV and PCV. The results with the symbols indicate the PCV full with plutonium oxide solution and the volume between the SCV and PCV filling with plutonium oxide solution, until full.

Figure 6.8 - Filling 5-inch PCV and 6-inch SCV with PuO2 and Flooding Water 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 0

1 2

3 4

5 6

7 8

k e

f f

+

2

Amount (liters) of water added to PuO2 k-safe 5" PCV Be 5" PCV C 5" PCV 5" PCV - FLD Celo 6" SCV Be 6 "SCV C 6" SCV 6" SCV - FLD Celo

Revision 1 S-SAR-G-00001 6-27 The cases with the plutonium oxide solution filling the PCV are shown to be subcritical, achieving a maximum keff + 2 = 0.814, Table 6.19, Case 6. In these cases no plutonium oxide solution is in the SCV, only water from filling the shipping package.

As increasing amounts of water mix with the plutonium oxide in the shipping package, the PCV overflows filling the SCV with the plutonium oxide solution. Thus, there is plutonium oxide solution in the PCV as well as the SCV. The cases of filling the PCV and SCV with plutonium oxide solution remains below ksafe with a maximum at keff + 2 = 0.858, Table 6.19, Case 12. In this case (Table 6.19, Case 12), 7.123 L water is added to the plutonium oxide in the shipping package, which completely fills the PCV, but only partially fills the SCV, with the plutonium oxide solution. Totally filling both the PCV and SCV (7.793 L water added to the plutonium oxide in the shipping package) with the plutonium oxide solution has also been demonstrated to be below ksafe with a keff + 2 = 0.855, Table 6.19, Case 13. In addition, when impurities (Be or C) are mixed with the oxide, the fissile mass of the mixture is reduced and consequently lowers the keff of the system, as shown in Figure 6.8 and Table 6.19 through Table 6.21.

Revision 1 S-SAR-G-00001 6-28 Table 6.19 - Filling 5-inch PCV and 6-inch SCV with PuO2 and Flooding Water Case No.

Filename Description PuO2

Density, g/cc keff keff +2
1.

nrc_su._PuO_fld_5PCV_noBe_ful.100.out PCV intact. CC, 3013 removed. PuO2 dry. Water between SCV-PCV.

10.8921 0.6639 0.0011 0.667

2.

nrc_su._PuO_fld_5PCV_noBe_ful.110.out Same as #1 - 1 liter water added to PCV 4.1131 0.7182 0.0012 0.721

3.

nrc_su._PuO_fld_5PCV_noBe_ful.120.out Same as #2 - 2 liters water added to PCV 2.8466 0.7649 0.0013 0.768

4.

nrc_su._PuO_fld_5PCV_noBe_ful.130.out Same as #2 - 3 liters water added to PCV 2.3123 0.7903 0.0014 0.794

5.

nrc_su._PuO_fld_5PCV_noBe_ful.140.out Same as #2 - 4 liters water added to PCV 2.0176 0.8047 0.0014 0.808

6.

nrc_su._PuO_fld_5PCV_noBe_ful.4826.out 4.826 L water added to PCV (totally full). PCV intact. CC and 3013 removed.

1.8584 0.8107 0.0015 0.814

7.

nrc_su._PuO_fld_6SCV_noBe_ful.5450.out PCV intact. CC and 3013 removed. 5.540 L water added to PCV, solution spilling into SCV.

1.7675 0.8110 0.0015 0.814

8.

nrc_su._PuO_fld_6SCV_noBe_ful.5746.out PCV intact. CC and 3013 removed. 5.746 L water added to PCV, solution spilling into SCV.

1.7308 0.8231 0.0014 0.826

9.

nrc_su._PuO_fld_6SCV_noBe_ful.6042.out PCV intact. CC and 3013 removed. 6.042 L water added to PCV, solution spilling into SCV.

1.6975 0.8334 0.0014 0.837

10.

nrc_su._PuO_fld_6SCV_noBe_ful.6338.out PCV intact. CC and 3013 removed. 6.338 L water added to PCV, solution spilling into SCV.

1.6670 0.8460 0.0015 0.849

11.

nrc_su._PuO_fld_6SCV_noBe_ful.6689.out PCV intact. CC and 3013 removed. 6.689 L water added to PCV, solution spilling into SCV.

1.6341 0.8538 0.0015 0.857

12.

nrc_su._PuO_fld_6SCV_noBe_ful.7123.out PCV intact. CC and 3013 removed. 7.123 L water added to PCV, solution spilling into SCV.

1.5978 0.8542 0.0016 0.858

13.

nrc_su._PuO_fld_6SCV_noBe_ful.7793.out PCV intact. CC and 3013 removed. 7.793 L water added to PCV, solution spilling into SCV. SCV completely full.

1.5491 0.8510 0.0017 0.855

Revision 1 S-SAR-G-00001 6-29 Table 6.20 - Filling 5-inch PCV and 6-inch SCV with PuO2, Beryllium and Flooding Water Case No.

Filename Description PuO2

Density, g/cc keff keff +2
1.

nrc_su._PuO_fld_5PCV_Be_ful.100.out PCV intact. CC, 3013 removed.

PuO2 dry. Added 500 g Be.

7.2986 0.5899 0.0011 0.593

2.

nrc_su._PuO_fld_5PCV_Be_ful.110.out Same as #1 - 1 liter water added to PCV 3.5611 0.6865 0.0016 0.690

3.

nrc_su._PuO_fld_5PCV_Be_ful.120.out Same as #2 - 2 liters water added to PCV 2.6068 0.7454 0.0015 0.749

4.

nrc_su._PuO_fld_5PCV_Be_ful.130.out Same as #2 - 3 liters water added to PCV 2.1704 0.7709 0.0013 0.774

5.

nrc_su._PuO_fld_5PCV_Be_ful.140.out Same as #2 - 4 liters water added to PCV 1.9202 0.7849 0.0014 0.788

6.

nrc_su._PuO_fld_5PCV_Be_ful.4599.out 4.599 L water added to PCV (totally full). PCV intact. CC and 3013 removed.

1.8157 0.7905 0.0016 0.794

7.

nrc_su._PuO_fld_6SCV_Be_ful.5223.out PCV intact. CC and 3013 removed. PuO2 mixed with 500 g Be. 5.223 L water added to PCV, solution spilling into SCV.

1.7294 0.7950 0.0018 0.799

8.

nrc_su._PuO_fld_6SCV_Be_ful.5519.out PCV intact. CC and 3013 removed. PuO2 mixed with 500 g Be. 5.519 L water added to PCV, solution spilling into SCV.

1.6945 0.8029 0.0015 0.806

9.

nrc_su._PuO_fld_6SCV_Be_ful.5815.out PCV intact. CC and 3013 removed. PuO2 mixed with 500 g Be. 5.815 L water added to PCV, solution spilling into SCV.

1.6628 0.8212 0.0015 0.825

10.

nrc_su._PuO_fld_6SCV_Be_ful.6111.out PCV intact. CC and 3013 removed. PuO2 mixed with 500 g Be. 6.111 L water added to PCV, solution spilling into SCV.

1.6338 0.8333 0.0016 0.837

11.

nrc_su._PuO_fld_6SCV_Be_ful.6463.out PCV intact. CC and 3013 removed. PuO2 mixed with 500 g Be. 6.463 L water added to PCV, solution spilling into SCV.

1.6026 0.8399 0.0017 0.844

12.

nrc_su._PuO_fld_6SCV_Be_ful.6896.out PCV intact. CC and 3013 removed. PuO2 mixed with 500 g Be. 6.896 L water added to PCV, solution spilling into SCV.

1.5680 0.8415 0.0015 0.845

13.

nrc_su._PuO_fld_6SCV_Be_ful.7567.out PCV intact. CC and 3013 removed. PuO2 mixed with 500 g Be. 7.567 L water added to PCV, solution spilling into SCV. SCV completely full.

1.5217 0.8398 0.0015 0.843

Revision 1 S-SAR-G-00001 6-30 Table 6.21 - Filling 5-inch PCV and 6-inch SCV with PuO2, Carbon and Flooding Water Case No.

Filename Description PuO2

Density, g/cc keff keff

+2

1.

nrc_su._PuO_fld_5PCV_C_ful.100.out PCV intact. CC, 3013 removed.

PuO2 dry. Added 1000 g carbon.

6.2065 0.5101 0.0009 0.512

2.

nrc_su._PuO_fld_5PCV_C_ful.110.out Same as #1 - 1 liter water added to PCV 3.3232 0.6327 0.0014 0.636

3.

nrc_su._PuO_fld_5PCV_C_ful.120.out Same as #2 - 2 liters water added to PCV 2.4948 0.7003 0.0015 0.704

4.

nrc_su._PuO_fld_5PCV_C_ful.130.out Same as #2 - 3 liters water added to PCV 2.1016 0.7399 0.0017 0.744

5.

nrc_su._PuO_fld_5PCV_C_ful.140.out Same as #2 - 4 liters water added to PCV 1.8720 0.7597 0.0014 0.763

6.

nrc_su._PuO_fld_5PCV_C_ful.4478.out 4.478 L water added to PCV (totally full). PCV intact. CC and 3013 removed.

1.7930 0.7649 0.0015 0.768

7.

nrc_su._PuO_fld_6SCV_C_ful.5102.out PCV intact. CC and 3013 removed. PuO2 mixed with 1000 g carbon. 5.102 L water added to PCV, solution spilling into SCV.

1.7090 0.7728 0.0015 0.776

8.

nrc_su._PuO_fld_6SCV_C_ful.5398.out PCV intact. CC and 3013 removed. PuO2 mixed with 1000 g carbon. 5.398 L water added to PCV, solution spilling into SCV.

1.6751 0.7812 0.0014 0.784

9.

nrc_su._PuO_fld_6SCV_C_ful.5694.out PCV intact. CC and 3013 removed. PuO2 mixed with 1000 g carbon. 5.694 L water added to PCV, solution spilling into SCV.

1.6443 0.7972 0.0016 0.801

10.

nrc_su._PuO_fld_6SCV_C_ful.5990.out PCV intact. CC and 3013 removed. PuO2 mixed with 1000 g carbon. 5.990 L water added to PCV, solution spilling into SCV.

1.6161 0.8110 0.0016 0.815

11.

nrc_su._PuO_fld_6SCV_C_ful.6342.out PCV intact. CC and 3013 removed. PuO2 mixed with 1000 g carbon. 6.342 L water added to PCV, solution spilling into SCV.

1.5857 0.8180 0.0015 0.821 12 nrc_su._PuO_fld_6SCV_C_ful.6775.out PCV intact. CC and 3013 removed. PuO2 mixed with 1000 g carbon. 6.775 L water added to PCV, solution spilling into SCV.

1.5521 0.8198 0.0014 0.823

13.

nrc_su._PuO_fld_6SCV_C_ful.7446.out PCV intact. CC and 3013 removed. PuO2 mixed with 1000 g carbon. 7.446 L water added to PCV, solution spilling into SCV.

SCV completely full.

1.5071 0.8183 0.0016 0.822

Revision 1 S-SAR-G-00001 6-31 Additional models were developed to flood all of the remaining compartments of the 9975 shipping package. As shown in Table 6.19 through Table 6.21, the cases without impurities yielded the highest keff and have the SCV and PCV flooded with plutonium oxide solution.

Therefore, this series of cases was modified to also flood the Celotex insulation with water and the results are presented in Table 6.22. These cases represent the Celotex being replaced with water only because the fissile solution is judged to remain in the primary and secondary containment vessels.

Revision 1 S-SAR-G-00001 6-32 Table 6.22 - Filling 6-inch SCV with PuO2 - Celotex Flooded Case No.

Filename Description PuO2

Density, g/cc keff keff +2
1.

nrc_su._PuO_fld_5PCV_noBe_ful_fld_celo.100.out PCV intact. CC, 3013 removed. PuO2 dry.

Water between SCV-PCV.

10.8921 0.6802 0.0013 0.683

2.

nrc_su._PuO_fld_5PCV_noBe_ful_fld_celo.110.out Same as #1 - 1 liter water added to PCV 4.1131 0.7455 0.0013 0.749

3.

nrc_su._PuO_fld_5PCV_noBe_ful_fld_celo.120.out Same as #2 - 2 liters water added to PCV 2.8466 0.7955 0.0015 0.799

4.

nrc_su._PuO_fld_5PCV_noBe_ful_fld_celo.130.out Same as #2 - 3 liters water added to PCV 2.3123 0.8214 0.0016 0.825

5.

nrc_su._PuO_fld_5PCV_noBe_ful_fld_celo.140.out Same as #2 - 4 liters water added to PCV 2.0176 0.8346 0.0016 0.838

6.

nrc_su._PuO_fld_5PCV_noBe_ful_fld_celo.4826.out 4.826 L water added to PCV (totally full). PCV intact. CC and 3013 removed. Celotex flooded.

1.8584 0.8407 0.0016 0.844

7.

nrc_su._PuO_fld_6SCV_noBe_ful_fld_celo.5450.out PCV intact. CC and 3013 removed. 5.5450 L water added to PCV, solution spilling into SCV. Celotex flooded.

1.7675 0.8448 0.0014 0.848

8.

nrc_su._PuO_fld_6SCV_noBe_ful_fld_celo.5746.out PCV intact. CC and 3013 removed. 5.746 L water added to PCV, solution spilling into SCV. Celotex flooded.

1.7308 0.8587 0.0015 0.862

9.

nrc_su._PuO_fld_6SCV_noBe_ful_fld_celo.6042.out PCV intact. CC and 3013 removed. 6.042 L water added to PCV, solution spilling into SCV. Celotex flooded.

1.6975 0.8875 0.0015 0.891

10.

nrc_su._PuO_fld_6SCV_noBe_ful_fld_celo.6338.out PCV intact. CC and 3013 removed. 6.338 L water added to PCV, solution spilling into SCV. Celotex flooded.

1.6670 0.9076 0.0015 0.911

11.

nrc_su._PuO_fld_6SCV_noBe_ful_fld_celo.6689.out PCV intact. CC and 3013 removed. 6.689 L water added to PCV, solution spilling into SCV. Celotex flooded.

1.6341 0.9124 0.0017 0.916

12.

nrc_su._PuO_fld_6SCV_noBe_ful_fld_celo.7123.out PCV intact. CC and 3013 removed. 7.123 L water added to PCV, solution spilling into SCV. Celotex flooded.

1.5978 0.9096 0.0015 0.913

13.

nrc_su._PuO_fld_6SCV_noBe_ful_fld_celo.7793.out PCV intact. CC and 3013 removed. 7.793 L water added to PCV, solution spilling into SCV. SCV completely full. Celotex flooded.

1.5491 0.9086 0.0015 0.912

Revision 1 S-SAR-G-00001 6-33 As shown in Figure 6.8 and Table 6.22, for the series of cases with an additional layer of reflection created by replacing the Celotex with water, all cases remain subcritical. The highest keff + 2 = 0.916 (Table 6.22, Case 11) is achieved when 6.689 L water is added to the plutonium oxide in the shipping package, completely filling the PCV, but only partially filling the SCV, with plutonium oxide solution. In addition, Table 6.22 shows that adding 7.793 L water to the plutonium oxide in the shipping package, completely filling the PCV and SCV with plutonium oxide solution, remains below ksafe with a keff + 2 = 0.912, Table 6.22, Case 13.

Thus, all keff + 2 values in Tables 6.9 through Table 6.22 are below the ksafe of 0.943, derived in Section 6.6.1.

Therefore, the 10 CFR 71.55(b) requirements related to single unit analyses are satisfied for these fissile masses.

6.4.3.2 NCT Array Results In the NCT undamaged drum array model, an infinite array of drums was analyzed with each drum in dry conditions and additional cases with the Celotex flooded. Table 6.23 demonstrates that the 9975 with plutonium oxide in convenience can, with and without the 3013 container, in dry conditions, is subcritical with the highest keff + 2 of 0.655 for a dry system (Table 6.23, Cases 1 and 5). Table 6.23 also shows water flooding of the Celotex is subcritical.

All keff + 2 values in Table 6.23 are below the ksafe of 0.943.

Table 6.23 - 9975 Array Model - NCT Cases Case No.

File ID Description keff keff

+2

1. nrc_nct.cyl3013.out Infinite drum array, dry fissile material 0.6520 0.0011 0.655
2. nrc_nct.cyl3013_celofld.out Same as #1 water as Celotex 0.6099 0.0010 0.612
3. nrc_nct.cyl3013_h2orefl.out Same as #1 w/water between drums 0.6102 0.0009 0.613
4. nrc_nct.cyl3013_h2orefl_celofld.out Same as #1 w/water between drums, water as Celotex 0.6099 0.0010 0.612
5. nrc_nct.cylno3013.out Infinite drum array, dry fissile material, no 3013 containers 0.6524 0.0011 0.655
6. nrc_nct.cylno3013_celofld.out Same as #5, water as Celotex 0.6046 0.0010 0.607 nrc_nct.cylno3013_h2orefl.out Same as #5, w/water between drums 0.6049 0.0012 0.608
7. nrc_nct.cylno3013_h2orefl_celofld.out Same as #5 w/water between drums, water as Celotex 0.6042 0.0010 0.607

Revision 1 S-SAR-G-00001 6-34 Therefore, the 10 CFR 71.55(d) and 71.59(a)(1) requirements related to NCT analyses are satisfied for these fissile masses.

6.4.3.3 HAC Array Results Table 6.24 shows that all keff + 2 values are less than ksafe for the damaged array cases. This demonstrates that moving the fissile units closer together (Table 6.24 - Case 1, the bounding closest position case) only produces a slightly higher keff than when all of the fissile units are centered within the 9975 shipping package (Table 6.24 - Case 5, the bounding centered position case), on the order of 0.8% difference. Thus, the base HAC model, the infinite array of 2x2x2 clusters with the fissile material units closest together (Table 6.24 - Case 1) within the array has the highest keff + 2 of 0.737.

Table 6.24 - 9975 Array Model - HAC Cases Case No.

File ID Description keff keff +2

1. nrc_hac.cyl3013_2x2x2.out 2x2x2 cluster, infinite array Fissile at closest position 0.7346 0.0011 0.737
2. nrc_hac.cyl3013_2x2x2_PCVfl.out Same as #1, PCV flooded 0.7209 0.0012 0.724
3. nrc_hac.cyl3013_2x2x2_PCVSCVfl.out Same as #1, PCV/SCV flooded 0.7120 0.0010 0.714
4. nrc_hac.cyl3013_2x2x2_SCVfl.out Same as #1, SCV flooded 0.7144 0.0011 0.717
5. nrc_hac.cyl3013_2x2x2_symm.out 2x2x2 cluster, infinite array Fissile at centered position 0.7287 0.0010 0.731
6. nrc_hac.cyl3013_2x2x2_PCVfl_symm.out Same as #5, PCV flooded 0.7135 0.0010 0.716
7. nrc_hac.cyl3013_2x2x2_PCVSCVfl_symm.out Same as #5, PCV/SCV flooded 0.7008 0.0011 0.703
8. nrc_hac.cyl3013_2x2x2_SCVfl_symm.out Same as #5, SCV flooded 0.7065 0.0013 0.710 A conservative analysis was performed flooding the 9975 shipping package with water to the fullest extent while modeled as an infinite array. Various models were developed that flooded the different compartments (i.e., 3013, PCV, SCV, Celotex) of the 9975 shipping package, while flooding the convenience can containing the fissile solution. As seen in Table 6.24, for the base HAC analysis, the configuration with the fissile units at their closest position (Table 6.24, Case
1) yields the highest keff + 2 which also holds true for the cases with the convenience can flooded. Thus, calculations were performed flooding the different compartments of the 9975 shipping package, which has demonstrated that the case where the convenience can/3013 configuration was flooded while the remainder of the 9975 shipping package remains dry (Table 6.25, Case 2) yields the highest keff + 2 of 0.938.

Revision 1 S-SAR-G-00001 6-35 Table 6.25 - 9975 Array Model - Flooded Convenience Can HAC Cases Case No.

File ID Description keff keff +2

1. nrc_hac.cyl_CCfl_2x2x2.out:

Convenience Can Flooded Fissile at closest position 0.9149 0.0014 0.918

2. nrc_hac.cyl_CCfl_3013fl.out:

Same as #1, 3013 flooded 0.9349 0.0013 0.938

3. nrc_hac.cyl_CCfl_allfl.out:

Same as #1, 3013, PCV, SCV, water as Celotex 0.7875 0.0013 0.791

4. nrc_hac.cyl_CCfl_3013dry_PCVSCVfl.out:

Same as #1, 3013 dry, PCV, SCV flooded 0.8443 0.0015 0.848

5. nrc_hac.cyl_CCfl_3013dry_allfl.out:

Same as #1, 3013 dry, PCV, SCV, water as Celotex 0.7647 0.0014 0.768

6. nrc_hac.cyl_CCL_2x2x2_symm.out:

Convenience Can Flooded Fissile at centered position 0.9038 0.0016 0.907 Therefore all keff + 2 values for the HAC array analysis as shown in Table 6.24 and Table 6.25 are below the ksafe of 0.943. It should be noted that the PCV/SCV orientations in the HAC model are conservative in regards to the movements possible due to uniform change of the charred Celotex dimensions. Therefore, the 10 CFR 71.55(e) and 71.59(a)(2) requirements related to HAC analyses for those masses are satisfied.

6.5 CRITICALITY SAFETY INDEX The calculation of the CSI for the 9975 shipping package is required to follow the explicit equations specified in 10 CFR 71.59:

(a) A fissile material package must be controlled by either the shipper or the carrier during transport to assure that an array of such packages remains subcritical. To enable this control, the designer of a fissile material package shall derive a number "N" based on all the following conditions being satisfied, assuming packages are stacked together in any arrangement and with close full reflection on all sides of the stack by water:

(1) Five times "N" undamaged packages with nothing between the packages would be subcritical; (2) Two times "N" damaged packages, if each package were subjected to the tests specified in § 71.73 ("Hypothetical accident conditions") would be subcritical with optimum interspersed hydrogenous moderation; and (3) The value of "N" cannot be less than 0.5.

(b) The CSI must be determined by dividing the number 50 by the value of "N" derived using the procedures specified in paragraph (a) of this section. The value of the CSI may be zero provided that an unlimited number of packages are subcritical, such that the value of "N" is effectively equal to infinity under the procedures specified in paragraph (a) of this section.

Any CSI greater than zero must be rounded up to the first decimal place.

(c) For a fissile material package which is assigned a CSI value--

Revision 1 S-SAR-G-00001 6-36 (1) Less than or equal to 50, that package may be shipped by a carrier in a nonexclusive use conveyance, provided the sum of the CSIs is limited to less than or equal to 50.

(2) Less than or equal to 50, that package may be shipped by a carrier in an exclusive use conveyance, provided the sum of the CSIs is limited to less than or equal to 100.

(3) Greater than 50, that package must be shipped by a carrier in an exclusive use conveyance, provided the sum of the CSIs is limited to less than or equal to 100.

The CSI is conservatively computed for both the NCT and HAC, with the CSI calculation shown in Table 6.26.

Table 6.26 - CSI Calculation Calculate the value of N for NCT:

5*N = (infinite), so N = /5 =

The CSI is defined by 10 CFR 71.59 as, CSI 50/N = 50/ = 0.0 Rounding up to the first decimal:

CSI = 0.0 Calculate the value of N for HAC:

2*N = (infinite), so N = /2 =

The CSI is defined by 10 CFR 71.59 as, CSI 50/N = 50/ = 0.0 Rounding up to the first decimal:

CSI = 0.0 The CSI calculation in Table 6.26 derives a CSI in the infinite array NCT and HAC configurations equal to 0.0 for the 9975 package with the plutonium oxide, content envelope C.12.

6.6 CRITICAL BENCHMARK EXPERIMENTS This section provides the validation of the CSAS26 criticality analysis sequence contained in Version 5 of the SCALE package. Validation is required by the criticality safety standard ANSI/ANS-8.1-1998[10]. This section describes the method, computer program and cross-section libraries used, experimental data, areas of applicability, and bias and uncertainty.

The criticality safety module used is CSAS26, embedded in SCALE Version 5. CSAS26 includes the SCALE Material Information Processor, BONAMI, CENTRM, and KENO-VI. The Material Information Processor generates atom densities for standard compositions, prepares geometry data for resonance self-shielding, and creates data input files for the cross-section processing codes. The BONAMI and CENTRM codes are used to prepare a resonance-corrected cross-section library in AMPX working format. The KENO-VI code uses Monte Carlo techniques to calculate keff.

6.6.1 Code Validation and Bias for Pu Oxide Contents SCALE 5 (KENO-VI) using the 238-group ENDF/B-V neutron cross-section library has been validated for Pu oxide, Pu solution, highly enriched uranium (HEU) oxide, and HEU solution

Revision 1 S-SAR-G-00001 6-37 systems on the SRNS Criticality Safety Advanced Computing Center[7]. The biased keff values, Table 6.27, were taken from the validation reference[7] and were based on the Lower Tolerance Band (LTB) for the system(s) considered. No critical experiments similar to the 9975 shipping package systems with Pu/U oxide are available. Therefore, this study chose a wide range of validation experiments. Table 6.27 shows the biased keff and ksafe values for different systems.

The NUREG document[9] specifies a required minimum subcritical margin (MSM) of 0.05 for packaging applications. Because a large MSM has been used for the 9975 analysis using common fissile material (i.e., 239Pu and 235U) and drum components, no additional margin due to areas of applicability is necessary.

The results of the validation report were evaluated to determine the ksafe value applicable to this analysis. It is seen from Table 6.27 that the lowest ksafe value derived from the validations is 0.943. Therefore, this evaluation uses a ksafe value of 0.943.

Table 6.27 - Validation Values, SCALE 5 (KENO-VI), 238-group ENDF/B-V System Lower Tolerance Band MSM

= ksafe Plutonium Solution 0.9934 0.05 0.943 Plutonium Oxide, dry 0.9953 0.05 0.945 The LTB values are based on the following equations[7] for which the values of H/X and AEG (Average Energy Group) are taken from the multiple calculations performed.

LTB (Solution - PuO2) = 0.99341 + [0.0000053803

  • H/239Pu] + [-0.0000000009576 * (H/239Pu)2]

LTB (Dry - PuO2) = 0.99529 + [0.000086341

  • AEG] + [-0.00000069867 * (AEG)2]

Where H/X is the atom ratio of hydrogen to 239Pu and AEG is the energy of a neutron causing fission and the constants are those provided by the quoted reference.

Revision 1 S-SAR-G-00001 6-38

6.7 REFERENCES

1. Packaging and Transportation of Radioactive Material, Title 10, Code of Federal Regulations, Part 71, Washington, DC (January 2012).
2. L.M. Petrie, et al., SCALE: A Modular Code System for Performing Standardized Computer Analysis for Licensing Evaluation, ORNL/TM-2005/39, Version 5, Vol. II, Book 2, Sect. F11, Oak Ridge National Laboratory, Oak Ridge, TN (April 2005).
3. M. Harris, Nuclear Criticality Safety Evaluation: 9975 Shipping Package Analysis with Plutonium Oxide Contents for NRC Safety Analysis Report, N-NCS-A-00029, Revision 1, Savannah River Nuclear Solutions, Aiken, SC (September 2014). [Included as Appendix 6.1]
4. Specification for Seamless and Welded Austenitic Stainless Steel Pipes, ASTM A312, American Society for Testing and Materials (1995).
5. A.H. Bridges, Software Configuration and Control Guidance for SCALE on SRS Personal Computers (U), SRNS-RP-2008-00150, Revision 1, Savannah River Nuclear Solutions, Aiken, SC (May 2011).
6. A.H. Bridges, SCALE Test Report for SRS Personal Computers (U), SRNS-RP-2008-00151, Revision 1, Savannah River Nuclear Solutions, Aiken, SC (May 2011).
7. L.M. Abney and A.H. Bridges, SCALE 5.0 Validation for SRNS Personal Computers (U),

SRNS-RP-2008-00153, Revision 0, Savannah River Nuclear Solutions, Aiken, SC (January 2009).

8. N.M. Green, et al., The LAW-238 Library - A Multigroup Cross-Section Library for Use in Radioactive Waste Analysis Calculations, ORNL/TM-12370, Oak Ridge National Laboratory, Oak Ridge, TN (August 1994).
9. Recommendations for Preparing the Criticality Safety Evaluation of Transportation Packages, NUREG/CR-5661, ORNL/TM-11936, Oak Ridge National Laboratory, Oak Ridge, TN (April 1997).
10. Nuclear Criticality Safety in Operations with Fissionable Material Outside Reactors, ANSI/ANS-8.1-1998, (1998).

Revision 1 S-SAR-G-00001 6-39 6.8 APPENDICES 6.1.

M. Harris, Nuclear Criticality Safety Evaluation: 9975 Shipping Package Analysis with Plutonium Oxide Contents for NRC Safety Analysis Report, N-NCS-A-00029, Revision 1, Savannah River Nuclear Solutions, Aiken, SC (September 2014).

6.2.

Input and Output Files (provided on CD).

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