ML25324A099
| ML25324A099 | |
| Person / Time | |
|---|---|
| Site: | 07109385 |
| Issue date: | 10/01/2025 |
| From: | Office of Nuclear Material Safety and Safeguards |
| To: | |
| Shared Package | |
| ML25324A098 | List: |
| References | |
| EPID L-2024-NEW-0008, CAC 001029 | |
| Download: ML25324A099 (1) | |
Text
1 Request for Additional Information Structural, Thermal, and Material Evaluations Certificate of Compliance No. 9385 Model No. IR-100ST Docket No. 71-9385, Revision No. 0 This request for additional information (RAI) identifies information needed by the U.S. Nuclear Regulatory Commission (NRC) staff (the staff) in connection with its review of the application.
The staff used NUREG-2216, Standard Review Plan for Transportation Packages for Spent Fuel and Radioactive Material: Final Report, (NUREG-2216) in its review of the application.
Each RAI describes information needed by the staff to complete its review of the application and to determine whether the applicant has demonstrated compliance with the regulatory requirements of 10 CFR Part 71.
STRUCTURAL EVALUATION RAI St-1 Provide the total number of locations where the weld detail applies for attachment of the support saddle (Item No. 5) to the housing base (Item No. 6) shown on the applications drawing No. IR100ST-B, Sheet 3, Revision 1, IR-100ST BODY ASSEMBLY, SAR.
The drawing No. R100ST-B, Section B-B, depicts the near side fillet weld detail for attachment of the support saddle (Item No. 5) to the housing base (Item No.
- 6) with a note in the tail that reads TYP, ITEM 5 to ITEM 6. Since the weld is shown only for the near side of the saddle, and there are two quantities of Item No. 5 (support saddle) specified in the bill of material, it is unclear the total number of locations (i.e., or 4 places) where this weld detail applies. Therefore, the applicant needs to include in the drawing the total number of locations the weld detail is to be applied.
This information is needed to determine compliance with the regulatory requirements in 10 CFR 71.33(a)(5)and 10 CFR 71.107(a).
Response: The specified fillet weld for the DU support saddles applies to both vertical sides on each support saddle. Sheet 3 of General Arrangement Drawing IR-100ST-B, Rev. 2, has been revised to clarify the weld specification for each support, i.e., two fillet welds on each support. The total of number of fillet welds for the two supports is four (4).
RAI St-2 Regarding the tie-down test:
a)
Provide the location on the package, on which vertical, horizontal, and transverse loads were applied while the package was tied down with two straps as shown in Figure 2.5-1 of the application.
b)
For the tie-down test, clarify if the vertical, if horizontal and transverse loads were applied simultaneously or not. If not, provide an explanation.
b)
Clarify if the unit was tested by swapping the magnitude of test loads in the horizontal and transverse directions. If not, provide an explanation.
Section 2.5.2 of the application notes that the loads of 583.4 pound-force (lbf),
294.6 lbf, and 120.0 lbf were applied in the longitudinal, lateral, and vertical directions, respectively, as shown in Figure 2.5-1. However, it does not provide the following information of importance for structural evaluation:
2
- 1) relevant details such as the test loads locations on the package,
- 2) whether the loads were applied in different directions simultaneously or separately, etc.
Since there are no restrictions on how the package is oriented with respect to the direction of travel during the transport, the package evaluation for the tie-down needs to be evaluated for all possible orientations to ensure that the limiting forces applied on the package tie-down are considered in the direction of vehicle travel and in the transverse direction.
This information is requested to determine compliance with the regulatory requirements in 10 CFR 71.45(b).
Response: As shown in Figure 2.5-1, the tie-down test for the IR-100ST package was performed using two straps inserted thru the sensor surround handle, which is the only possible package feature that could be utilized as a structural tie-down device. The three applied loads, i.e., vertical up, transverse, and longitudinal, were applied simultaneously to the stainless steel housing (transverse, longitudinal) and the bottom of the sensor surround (vertical) resisted by the two straps in the sensor surround handle.
SAR Figure 2.5-1 provides objective evidence of the applied loads from the 500-lbf and 1,000-lbf load cells for the three applied loads that were applied to the package. Any other possible orientation for tie-down of the IR-100ST package would not be as severe to secure the package via the sensor surround handle. The below photograph depicts the applied loading from the load cells for the transverse and longitudinal directions on the stainless steel housing.
RAI-St-3 Provide the temperature that the stainless steel body of the package was exposed when it was placed on a dry ice environment as noted in the Section 2.6.2 of the application.
Section 2.6.2 of the SAR notes that the IR-100ST stainless steel body was
3 exposed to a dry ice environment (-109 ºF [-40 ºC]) for an extended period of time in an ice chest without detrimental effects. The staff notes that -109 ºF is -78 ºC and -40 ºC is -40 ºF. Also, Sections 2.12.1.7.2.1 and 2.12.1.7.2.2 of the application note that the measured surface temperatures of the CTU-2 package were less than -20 ºF and -21 ºF, respectively. Clarify what temperatures the IR-100ST body was exposed to during the cold test.
This information is needed to determine compliance with the regulatory requirements in 10 CFR 71.71 and 71.73.
Response: As noted in Section 2.12.1.7.2.1, CTU-2 was placed within an ice chest with dry ice to ensure that the package would meet the regulatory test temperature of -20 ºF at the time of the free drop.
Because the test package was exposed to dry ice for a period of time to obtain a steady-state condition, the package experienced temperatures near that of the dry ice environment, i.e., 109.2 °F (78.5 °C), which is significantly lower than the regulatory temperature of -20 ºF. Section 2.6.2 of the SAR has been corrected to reflect the dry ice temperatures.
RAI-St-4 Explain why a package orientation to maximize damage at the outlet port end of the package was not considered for the hypothetical accident condition (HAC) free drop and puncture tests.
Section 2.12.1.5 of the application provides the technical basis to select a worst-case package orientation that could potentially compromise depleted uranium (DU) shield integrity and/or the special form source of the package under the free drop and puncture tests. The package drawing Nos. IR100ST-E, Revision 0, and IR100ST-F, Revision 0, depict a configuration and parts for the lock assembly and the outlet port assembly, respectively, that are attached to the package housing at the opposite ends. These drawings do not provide overall dimensions for the lock and outlet port assemblies. However, it appears, from these drawings and the package assembly drawing No. IR100ST-B, that the cantilever dimension from the housing base to the free end is greater for the outlet port assembly than that for the lock assembly, assuming these drawings are drawn to the scale. If the outlet port assembly is longer, the CG-over-Outlet Port Assembly free end corner orientation may cause overstress conditions at the assembly welded joint to the housing base (i.e., being a weak point) under the free drop and puncture tests. Therefore, the latter conditions need to be evaluated and included in the application, otherwise the applicant needs to provide a justification for not considering this orientation.
Note that the secondary objective of the HAC free drops is to fail the stainless steel body such that a potential air pathway into the interior would form, which could potentially result in a self-sustaining oxidation reaction of the DU and hence, result in a loss of shielding.
This information is needed to determine compliance with the regulatory requirements in 10 CFR 71.73(c)(1) and (3).
Response: The outlet port assembly has no impact on the location of the special form capsule within the DU shield. As noted in Section 2.7.1.1 of the SAR, the objective of the certification tests was to dislodge or move the special form capsule from its shielded position within the DU shield. The special form capsule attached to the end of the pigtail assembly is secured within the DU shield by the lock assembly. To
4 move the pigtail/special form capsule, the lock assembly would need to be damaged and/or failed, which did not occur with any of the free or puncture drop tests of the test packages. Additionally, the nearly identical IR-100 package was free dropped on the weaker brass outlet port plug without any effect on the shielding or position of the special form capsule. Note that the optional welded stainless steel outlet port of the IR-100ST is significantly stronger that the threaded brass safety plug utilized on outlet port on the IR-100 package. In addition, the failed fillet seam weld along the lower edge of the IR-100 stainless steel housing failed from the HAC Free Drop Test No. 3 exposed the interior cavity, which provided a larger pathway for air to enter the interior cavity for the HAC thermal test than a postulated failure of the outlet port.
Since the IR-100ST package has no sealed containment boundary in the stain steel housing, atmospheric air is free to pass through the package without restriction. As shown in Figure 3.4-2, the thermal test of the IR-100 package resulted in the complete combustion of the interior polyurethane foam. Note that this IR-100 test package also experienced a failed weld along the bottom edge of the package that allowed an additional pathway for air to enter the interior cavity, which contained the DU shield. At the conclusion of the thermal test, there was no self-sustaining oxidation reaction of the DU shield material.
The General Arrangement drawings for the lock assembly (IR100ST-E, Rev. 1) and the outlet port assembly (IR-100ST-F, Rev. 1) have been revised to include the overall dimensions for these assemblies.
THERMAL EVALUATION RAI-Th-1 Provide the following information:
a)
The model inputs such as thermal properties and boundary conditions (e.g., insolation) used in the ANSYS thermal model mentioned in the application.
b)
The version of ANSYS thermal model used to generate the model.
c)
Demonstration that the thermal model was appropriately converged (e.g.,
energy balances, residuals).
d)
Clarification that the thermal model accurately represents the design of the IR-100ST package by modeling package components (stainless steel housing, depleted uranium shielding, polyurethane foam).
e)
Appropriate boundary conditions including the bases for external heat transfer correlations and coefficient values as well as the radiant energy boundary conditions used in the analysis.
f)
Clarify if the design/analysis (e.g., ANSYS model generation and solution methodologies) of the Model No. IR-100ST package is performed under the NRC-approved quality assurance (QA) program.
Section 3.2.1 of the application indicated that thermal properties were not provided because package integrity was established by testing. However, section 3.3 provided package temperatures during normal conditions of transport (NCT) based on an ANSYS thermal model, which would require thermal property inputs and boundary conditions for calculations. Similarly, there was no explicit
5 discussion that the ANSYS thermal model accurately portrayed the Model No.
IR-100ST design. The model inputs (e.g., thermal properties such thermal conductivity, boundary conditions, package components modeled) and quality assurance (QA) discussions are needed in order to make a determination that model results are representative of the package during transport conditions.
In terms of clarifications of the boundary conditions, Section 3.31 of the application only refers to a 12-hour average, but did not specify the insolation value (e.g., 800 watts per square meter (W/m2)) and the package surfaces absorptivity and emissivity. Also, the application did not include a discussion about the bases for external heat transfer correlations and coefficient values and for the radiant energy boundary conditions used in the analysis.
This information is needed to determine compliance with the regulatory requirements in 10 CFR 71.35(a) and 71.41(a).
Response
- a. Conductivity values for Type 304 stainless steel material are obtained from those found in the ASME Boiler and Pressure Vessel Code (B&PVC) [1]
and are listed in Table 1. The conductivity of copper is from Table 2.23 of
[2] and the temperature dependent values are listed in Table 2. The thermal conductivity of the depleted uranium shield is from Equation 4.1.1-11 of [3] and the temperature dependent values are listed in Table 3 An unreinforced polyurethane material is considered for this analysis.
Unreinforced polyurethane elastomers have a thermal conductivity ranging from 0.972 to 2.71 BTU-in/(hr-ft²-°F) [4]. The polyurethane foam used in this analysis is based on General Plastics FR-3700 series foam with a density of 20 lbm/ft³-ft (pcf) with a conductivity of 0.349 BTU-in/(hr-ft²-°F) [5].
Conservatively, a lower value of 0.200 will be used in this analysis. The material properties of the non-metallic materials used in the model are generic in nature and their properties are listed in Table 4.
For radiation heat transfer properties, the internal components of the IR-100ST model are assumed to be bonded allowing for perfect conduction between bodies. Therefore, no optical properties are needed for the internal components of the model. However, the outer surfaces of the package are exposed to insolation loads and the radiate thermal energy to the environment. The external surfaces consist of the plastic jacket, the stainless-steel surfaces of the package, and the metallic surfaces of the identification plates. In addition, there is the surface emissivity of the hazard marking labels. The plates, fabricated from steel, are assumed to have the same emissivity as the stainless-steel body that they are secured. The hazard marking labels are also assumed to have the same emissivity and are not explicitly added to the model.
1 ASME Boiler and Pressure Vessel Code,Section II, Materials, Part D, Properties (Customary), 2017.
2 Rohsenow, W. M., Handbook of Heat Transfer, 3rd Edition, McGraw-Hill, New York, NY, 1998.
3 IAEA-TECDOC-949, Thermophysical properties of materials for water cooled reactors, International Atomic Energy Agency, June 1997.
4 https://www.matweb.com, Matweb Material Property Data Website, Last Accessed on 12/12/2023.
5 Design Guide for use of Last-A-Foam FR-3700 for Crash & Fire Protection of Radioactive Material, Issue 5, General Plastics Manufacturing Co., Tacoma WA.
6 The emissivity of as-received stainless steel has been measured to be 0.25 to 0.28 [6] while the emissivity of weathered stainless steel has been measured up to 0.46 [7]. The exterior surfaces of the housing are assigned a value of 0.30 to represent the effect of the rough finish of the data plates, labels, and a moderate level of wear and tear through use of the device. The solar absorptivity of Type 304 stainless steel is approximately 0.52 [8].
The surface emissivity of plastics ranges from 0.90 to 0.97 [9].
Conservatively, a value of 0.90 is used for the outer polyurethane surface.
The value for solar absorptivity for lighter colored (green) exterior plastic surfaces, as indicated in the general arrangement drawings and presented in [10] for solar radiation by surface color, is expected to between the values of 0.50 to 0.70. Conservatively, a slightly higher value of 0.8 is applied.
The emissivity and solar absorptivity of the packaging materials are shown in Table 5.
Table 1: ASTM Type 304 Stainless Steel Temperature, °F Conductivity BTU/(s-in-°F) 70 1.991x10-4 100 2.014x10-4 150 2.083x10-4 200 2.153x10-4 250 2.222x10-4 300 2.269x10-4 Table 2: Copper Temperature, °F Conductivity, BTU/(s-in-°F) 50 5.284x10-3 100 5.271x10-3 200 5.245x10-3 300 5.208x10-3 6 Frank, R., and Plagemann, W., Emissivity Testing of Metal Specimens, Boeing Analytical Engineering coordination sheet No. 2-3623-2-RF-C86-349, August 21, 1986. Testing accomplished in support of the TRUPACT-II design program 7 Azzazy, M., Emissivity Measurements of 304 Stainless Steel, prepared for Southern California Edison, September 6, 2000, TransNuclear File No. SCE-01.0100.
8 Gubareff, G., Janssen, J., and Torborg, R., Thermal Radiation Properties Survey, 2nd Edition, Honeywell Research Center, 1960.
9 The Engineering ToolBox (2009), Absorbed Solar Radiation, [online] Available at:
https://www.engineeringtoolbox.com/solar-radiation-absorbed-materials-d_1568.html, Last Accessed on 12/12/2023.
10 The Engineering ToolBox (2009), Absorbed Solar Radiation, [online] Available at:
https://www.engineeringtoolbox.com/solar-radiation-absorbed-materials-d_1568.html, Last Accessed on 12/12/2023.
7 Table 3: Material Properties of DU Temperature, °F Conductivity, BTU/(s-in-°F) 100 3.162x10-4 150 3.193x10-4 200 3.223x10-4 250 3.252x10-4 300 3.280x10-4 Table 4: Material Properties of Non-metals Material Conductivity, BTU/(s-in-°F)
Solid Polyurethane Elastomer 1.88x10-6 Polyurethane Foam 3.86x10-7 Table 5: Surface Radiation Properties Material Emissivity Solar Absorptivity External Sleeve Plastic 0.9 0.8 Stainless Steel 0.30 0.52 A view of the half-symmetry ANSYS thermal model is shown below:
This information has been added to SAR Sections 3.2 and 3.3.
- b. Figures 3.3-1 and 3.3-2, the ANSYS version utilized for the NCT thermal evaluation was identified the ANSYS 2024 R1 version of the software. This information has been added to the text in SAR Section 3.3.1.
- c.
Convergence was verified after three iterations to a convergence tolerance of 1x10-3 on the heat load based on convergence of the L2 norm of the
8 Newton Raphson load. A minimum tolerance of 0.8851x10-5 was set to prevent division by zero during these checks. A heat flow convergence value of 1.893x19-3 met the converged criteria of 8.9397x10-2. Therefore, the thermal model converged.
The ANSYS model included details and material thermal properties for the Type 304 stainless steel for the welded housing, the depleted uranium for the shield, the copper shims, the polyurethane foam in the interior of the housing, and the plastic jacket sensor surround, as noted above.
The thermal model takes advantage of the symmetric design of the package. Only one-half of the model is included. The symmetry plane is treated as an adiabatic surface (i.e., there is no heat transfer allowed through the plane). Since the base of the package is at rest and there is no insolation exposure, it maintained at a constant isothermal temperature equal to the ambient temperature.
Radiation is exchanged between the outer surfaces of the package and the environment at an ambient temperature of 100 °F. Radiation load is applied to the plastic sleeve bodies with an emissivity of 0.90 for plastic components and 0.3 for stainless steel components. All components in the package are considered bonded together and therefore, no radiation heat transfer is modeled between the components of the package.
Convection from the remaining exterior surfaces is based upon the convection relationships developed in Part 1, Chapter 3 of Guyer 11 utilizing the film temperature to calculate the pertinent properties.
Temperature dependent convection coefficient curves are generated based on the geometry and chrematistic length of the components as modeled. Convection curves to the hot ambient atmosphere for the various surfaces are shown in the figure below.
Convection Coefficients vs. Film Temperature 11 Guyer, Eric C., Handbook of Applied Thermal Design, Mc-Graw-Hill, 1989
9
- d. The design and thermal analysis of the IR-100ST package was performed in accordance with the Orano Federal Services (OFS) quality assurance program, which has been approved by the NRC. OFS is a subcontractor to INC.
RAI-Th-2 Describe the behavior of the plastic surround and PM Tag during the fire hypothetical accident conditions (HAC) and address its impact on the fires thermal evaluation.
Section 1.1 of the application mentioned the presence of a urethane surround and plastic PM Tag. However, section 3.4 of the application did not address the behavior of the plastic surround and plastic PM Tag during the fire HAC. In addition, the evaluation did not:
- 1) provide details of potential exothermic reactions (e.g., combustion), such as quantifying its thermal input (e.g., thermal energy release and heat of combustion (joules per kilogram (J/kg)) associated with the plastic PM Tag and surrounds (unspecified) mass relative to the thermal input to the package from the 800 degrees Celsius (°C ) fire;
- 2) discuss the potential impacts on the packages integrity, for example, on:
(i) shielding material (ii) special form source capsule (iii) melted plastic hindering pressure release from the housings openings that keep the package unpressurized, per section 3.1.4 of the application).
This information is needed to determine compliance with the regulatory requirements in 10 CFR 71.43(d), 71.51(a)(2), and 71.73(c)(4).
Response: Bayflex 110-50 plastic material is utilized for the urethane sensor surround. The Ultem-1000 plastic material is utilized for the PM Tag enclosure. Per the Safety Data Sheet (SDS), combustion of the Bayflex 110-50 material releases the following decomposition products:
carbon dioxide, carbon monoxide, oxides of nitrogen, dense black smoke, Isocyanate, and Isocyanic acid, with no flammable gases present. The Ultem-1000 material for the PM Tag enclosure softens between 412 °F (211 °C) and 419 °F (215 °C), and melts between 608 °F and 662 °F (320
°C and 350 °C). Note that these temperatures are well below the HAC 30-minute 1,475 °F (800 °C) thermal event. Since these plastic materials soften and melt prior to combustion, structural failure of the sensor surround would result from melting alone, not combustion. Failure of either the sensor surround or the PM Tag enclosure could potentially separate the LiFePO4 power cells from stainless steel housing. Increasing the temperature of the plastic materials to the HAC 1,475 °F (800 °C) thermal event would result in dissipating the plastic materials from the stainless steel housing. Because the sensor surround melts away, there would be no effect on the stainless steel, the DU shield, or the Special Form capsule located in the DU shield.
The three fill holes for the polyurethane foam are located on the top and ends of the stainless steel housing. These fill holes are protected by the pop-riveted stainless steel nameplate and packaging labels.
Because of the configuration, any melting plastic will not cover or
10 hinder the release of gases from the combustion of the polyurethane foam within the stainless steel housing.
RAI-Th-3 Provide the packages maximum surface temperature without insolation. As part of your response, explain if the package will meet the nonexclusive use temperature or the exclusive use temperature.
Section 3.3.1 of the application appears to indicate that the maximum outer package temperature (without a personnel barrier) may be 140 °F (based on the battery manufacturer data sheet), which is above the 122 °F non-exclusive use temperature. However, section 3.3.1 of the application also indicated that the maximum package temperature would be 100 °F and, therefore, less than the non-exclusive use temperature.
This information is needed in order to determine compliance with the regulatory requirements in 10 CFR 71.43(g).
Response: As noted in SAR Section 3.3.1, the maximum surface temperature with maximum insolation under a steady-state ambient temperature of 100 °F (38
°C) would be 155 °F (68 °C) on the top, horizontal surface of the stainless steel housing. Without insolation and essentially no decay heat from the Special Form capsule, the steady-state maximum surface temperature would equal the ambient temperature of 100 °F (38 °C). This temperature is below the regulatory temperature of 122 °F (50 °C) for non-exclusive use.
RAI-Th-4 Discuss the relevant differences between the Model No. IR-100ST package and the Model No. IR-100 certified test unit package that underwent the fire HAC test and explain the impacts of the differences.
Section 3.4.1 of the application indicated that the fire HAC thermal performance of the Model No. IR-100ST package would be similar to the thermal performance of the Model No. IR100. However, there was no explicit discussion that justified the appropriateness and relevance of the Model No. IR100 package thermal results (e.g., the same construction details), considering there are differences between the two packages (e.g., presence of plastic surround, presence of power cells).
Section 3.1.4 and 3.4.3 of the application stated that gas can move freely from the internal cavity of the depleted uranium shield to the ambient such that there is no pressurization of the package during NCT and HAC. This would indicate there are openings within the package to release internal pressures. A potential pressurization was indicated in section 3.4.2 of the application, which noted that the Model No.
IR100 test units polyurethane foam was consumed by the fire, thereby indicating combustion gases were released. In addition, it would appear that gaps would be small since the application noted the Model No. IR100 test units depleted uranium shield was not appreciably oxidized. There should be further information of the package vent mechanisms that ensure the IR-100ST package is not pressurized during NCT and HAC (e.g., expansion of foam and release of polyurethane combustion gases) and that the vent opening sizes are insufficient to cause oxidation of the depleted uranium and there will not be unintended effects by melting of the plastic surround that prevent venting (e.g., plugging vent openings).
This information is needed to determine compliance with the regulatory requirements in 10 CFR 71.35(a) and 71.51.
Response: The design of the stainless steel housing, DU shield, and polyurethane foam for both the IR-100 package and the IR-100ST
11 package are identical. Besides the addition of the sensor surround for the IR-100ST package, the only difference between these two packages is the stainless steel handle on the IR-100 package. There are also the optional lock and outport assemblies for the IR-100ST package compared to the IR-100 package. However, these assemblies are significantly stronger than assemblies utilized on the IR-100 package. All of the same mechanisms for venting gases, e.g.,
foam fill ports, from combustion of the polyurethane foam exist for both the IR-100 and IR-100ST packages. As noted in SAR Section 3.4.2, there was no degradation or oxidation of the DU shield from the HAC thermal test of the IR-100 package to satisfy it shielding safety function.
RAI-Th-5 Clarify that the Model No. IR-100ST package (with functioning power cells) will not be adversely affected by a -40 °C ambient temperature or specify an ambient temperature restriction for transport.
Section 2.6.4 of the application mentions that discharging and charging occur during transport, which can include cold ambient conditions (e.g., -29 °C, -40 °C).
However, the LithiumWerks datasheet (reference noted in section 1.2.1 of the application) for the packages PM Tag power cells mentions a charging temperature range of 0°C to 60°C and a discharging temperature range of -30°C to 60°C.
This information is needed to determine compliance with the regulatory requirements in 10 CFR 71.35(a) and 71.51.
Editorial clarification: Clarify the S-tube material(s) in drawing number IR100ST-C, considering it lists titanium, but SAR section 2.2.2 mentions the S-tube can be either titanium or Zircaloy.
Response: Because the IR-100 ST basic package is essentially identical to the IR-100 package, i.e., stainless steel welded housing, DU shield, and polyurethane foam, there is no is effect on the package from exposure to a temperature of -40 °F (-40 °C). Charging or discharging the LiFePO4 power cells in their reported temperature ranges [charging:
32 °F to 140 °F (0 °C to 60 °C), discharging: -22 °F to 140 °F (-30 °C to 60 °C)] has no effect on the metallic materials (stainless steel, DU) of the IR-100ST package. These temperature ranges only applicable to the power cells in operation, which part of the sensor surround that is not related to the shielding safety function of the IR-100ST package.
Note that the S-tube for the IR-100ST package is fabricated only from titanium. SAR Section 2.2.2 has been corrected to reflect only this material for the S-tube, as specified on INC general arrangement drawing IR100ST-C.
MATERIALS EVALUATION RAI-M-1 Update the lists of components in the Model No.IR-100ST package drawings to include component and material specifications for the following items:
a)
The pigtail assembly that must remain intact and secured to the special form radioactive source capsule to prevent an unintended displacement of the radiographic source from its required position inside the depleted uranium (DU) shield assembly during normal conditions of transport (NCT) and hypothetical accident conditions (HAC);
12 b)
The not-important-to-safety (NITS) Li-ion power cells inside the PM tag assembly that are described and referenced in section 1.2.1 of the application, considering that, for certain battery types different from those described in section 1.2.1, a thermal runaway reaction could be initiated for NCT events and common electrical faults.
The staff identified that the Model No. IR-100ST application indicates that the pigtail is a device that must remain intact and secured to the special form radioactive source capsule and the lock assembly to ensure that the radioactive source is not free to move from its safe shielded position in the middle of the S-tube inside the depleted uranium (DU) shield assembly. Therefore, the staff infers that the pigtail should be considered an important to safety (ITS) component, and as such, the material specifications for pigtail assembly should be included in the package drawings.
The staff recognizes that a thermal runaway reaction in the Li-ion batteries is expected to occur during the HAC thermal test of 10 CFR 71.73(c)(4), and such exothermic reactions are not prohibitive events for the HAC thermal test provided that the additional heat inputs into the package due to thermal runaway reaction plus organic material combustion reactions are adequately evaluated to demonstrate compliance with 10 CFR 71.51(a)(2). However, the package must meet the requirements for 10 CFR 71.43(d) for all routine operations and NCT by not undergoing significant chemical, galvanic, or other reactions under these conditions.
The staff reviewed the Li-ion battery specifications and consensus standards described and referenced in section 1.2.1 of the application and confirmed that these battery specifications and associated consensus standards adequately demonstrate that the batteries will not be susceptible to thermal runaway reaction during routine operations and NCT, including common electrical faults that can occur in Li-ion batteries, such as short circuit, overcharge and over-discharge.
To ensure adequate control of the material and component specifications for the package, the NITS safety classification for the Li-ion batteries should be supported by including the battery specification cited in section 1.2.1 of the application in the drawings. Otherwise, the lack of a battery specification in the drawings could potentially be prone to misinterpretation as allowing other battery types that may be susceptible to thermal runaway for routine operations and NCT.
This information is needed to determine compliance with the regulatory requirements in 10 CFR 71.31(c) and 71.43(d).
Response: The pigtail is not a component of the IR-100ST packaging.
Rather, it is a payload as identified in Chapter 4.0, Containment of the SAR. The pigtail is classified as a Radiography Source Assembly, as described in ANSI N542. The pigtail is registered as a Sealed Source (Registry of Sealed Sources and Devices, Safety Evaluation of Sealed Sources Number CA384S114S) as required by 10 CFR §34.20. This payload has been certified in accordance with 10 CFR §34.20 and Sections 8.8 and 8.9 of ANSI N432-1980, as required.
Similar to all other US manufactured industrial radiography cameras, the sealed source utilized in the packaging is not selected by the manufacturer; it is selected by the device owner. The device owner may choose from any similarly licensed sealed sources specified for use in the IR-100ST packaging. Therefore, licensing a specific sealed,
13 special form source as a component of the camera is not part of the certification of the IR-100ST packaging.
The specific LiFePO4 power cells identified in Section 1.2.1 of the SAR have been added to Section A-A and the parts list on SAR Drawing IR100ST-D, Rev. 1. Note that these power cells are the only lithium power cells that are authorized in the PM Tag Assembly for the IR-100ST package.
RAI-M-2 For the HAC thermal test of 10 CFR 71.73(c)(4), address whether there is any potential for significant pressure buildup inside the stainless steel housing of the IR-100ST package during the event that could lead to a failure of the stainless steel housing welds or base metal. The staff requests that the evaluation of potential pressure buildup inside the package housing consider additional heat inputs due to exothermic reactions that are expected to occur during the HAC thermal event, including combustion of organic materials and thermal runaway in the Li-ion batteries.
If there is a significant risk of pressure buildup to cause a failure of the stainless steel housing, address the potential consequences of a failure of the stainless steel housing during the thermal test, including the potential for escape or movement of the radioactive source and the ingress of air that may lead to high temperature oxidation of the depleted uranium (DU) shield casting that could result in a deterioration of gamma shielding performance and dispersion of uranium oxide powder outside of the stainless steel housing. For any such potential consequences, please demonstrate that the package can continue to meet the requirements of 10 CFR 71.51(a)(2).
The staff identified that the Model No. IR-100ST test sequence did not include HAC thermal tests, and the applicants evaluation of the Model No. IR-100ST package performance for HAC thermal test conditions relied on the results of previous HAC thermal tests performed on an IR-100 test unit for the certification of the NRC-approved Model No. IR-100 package design. The IR-100 test unit did not include the sensor/handle jacket assembly (comprised of significant combustible organic materials) and the Li-ion batteries, which are prone to thermal runaway during the HAC thermal test conditions. The application indicates that the HAC thermal test would initiate combustion of organic materials and thermal runaway in the Li-ion batteries, in addition to heat inputs from the HAC thermal test environment. Given that there was no failure in the stainless steel housing as a result of the preceding NCT and HAC drop tests of the Model No IR-100ST package, the staff needs assurance that the additional heat inputs into the package due to combustion of the new organic materials and thermal runaway in the Li-ion batteries would not cause pressurization and failure of the package body housing that could result in the package failing to meet applicable performance requirements in 10 CFR 71.51(a)(2).
This information is needed to determine compliance with the regulatory requirements in 10 CFR 71.51(a)(2).
Response: As noted in IR-100ST Safety Analysis Report (SAR), the stainless steel housing of the IR-100ST package contains no pressure boundary. Any gas that is created by combustion of the polyurethane foam surrounding the depleted uranium (DU) shield will exit the housing via the foam fill holes in the top of the housing sheet, as shown on SAR Figure 3.4-2. This lack of pressure buildup feature was demonstrated by the full-scale thermal test of the same stainless steel
14 housing design of the IR-100 package. The plastic sensor surround that contains the four small lithium power cells is secured to the exterior of the housing via (8) 3/16 inch pop stainless steel rivets. Assuming that the pop rivets survive the HAC free and puncture drop tests and retains the sensor surround to the housing, any heat input from melting/combustion of the sensor surround and/or a potential thermal runaway from the lithium power cells will not result in a temperature exceeding the melting temperature of the stainless steel housing (2,800 °F) or the DU shield (2,071 °F) within the housing, as noted in §3.4.2 of the SAR.
OFFICIAL USE ONLY - SECURITY RELATED INFORMATION FIGURES WITHHELD PER 10 CFR 2.390