ML23059A225
ML23059A225 | |
Person / Time | |
---|---|
Site: | 07103102 |
Issue date: | 03/27/2023 |
From: | Storage and Transportation Licensing Branch |
To: | US Dept of Transportation (DOT) |
Shared Package | |
ML23059A223 | List: |
References | |
EPID L-2022-DOT-0003 | |
Download: ML23059A225 (23) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION REPORT Docket No. 71-3102 Model No. DPR 200 Package United Kingdom Certificate GB/4120/B(U)
Revision 0
SUMMARY
By letter dated May 4, 2022 (Agencywide Documents Access and Management System
[ADAMS] Accession No. ML22203A069), the U.S. Department of Transportation (DOT) requested that the U.S. Nuclear Regulatory Commission (NRC) staff perform a review of the United Kingdom Certificate of Approval GB/4120/B(U), for the Model No. DPR 200 transport package and make a recommendation concerning the revalidation of the package for import and export use.
The NRC reviewed the information provided to DOT by Steris Applied Sterilization Technologies (the applicant) in its application for the Model No. DPR 200 package against the regulatory requirements of the International Atomic Energy Agency (IAEA) Specific Safety Requirements No. SSR-6, Regulations for the Safe Transport of Radioactive Material, 2018 Edition (SSR-6 or the Regulations). Based on the statements and representations in the information provided by DOT and the applicant, the staff recommends the revalidation of the United Kingdom Certificate of Approval GB/4120/B(U), for the Model No. DPR 200 package, for shipment as described in this safety evaluation report (SER).
1.0 GENERAL INFORMATION The DPR 200 is designed to ship Cobalt-60 high energy gamma sterilization sources to and from irradiation plants and manufacturing sites. The package is designed to ship both special form (SF) and non-special form (e.g., material that is no longer certified as SF or has lapsed SF certification).
2.0 STRUCTURAL EVALUATION The objective of the structural review is to verify that the design of the DPR 200 transportation package has adequate structural strength to withstand mechanical loads during normal conditions of transport (NCT) and accident conditions of transport (ACT). The review advises the DOT on whether the design meets the requirements set forth by SSR-6 for these conditions and provides guidance regarding the safety of the foreign-approved package design. The UK package design previously received Certificate of Approval GB/4120/B(U) for the transportation of special form and non-special form materials as a Type B(U) package.
2.1 Description of Structural Design The proposed DPR 200 transportation package is a containment vessel designed to transport special form and/or non-special form radioactive materials to and from irradiation plants and manufacturing sites. The transportation package main body consists of a cylindrical shape assembly that is attached to a square frame pallet at the bottom. The overall nominal dimension of the package is 1,200 mm x 1,200 mm with a height of 1,832 mm (i.e., including the pallet frame). The packaging has a maximum gross weight of 5,220 kg and, although its mass content Enclosure
is limited to 0.214 kg, the structural analysis was modelled considering a maximum mass content of 30 kg.
The DPR 200 package is comprised of four major structural components:
(1) the shield assembly - an upright-finned cylinder with an insulated jacket and a top shield that serves as an energy absorbing structure to provide protection to the cooling fins, closure and drain tube outlets, (2) the flask body - where the content of the container is stored inside a cavity, (3) the closure - used to seal the cavity, and (4) the pallet - where everything is connected to at the bottom.
All connections consist of a combination of welds, bolts, and link pins to ensure adequate transfer of the loads. The applicant lists all the packaging principal components, including the associated materials and mechanical properties, in SR-033, DPR 200 Type B(U) Design Safety Report, and drawing no. DR-001, DPR200 Container Assembly. The applicant also provided general drawings of the transportation package in drawings nos. DR-001 thru DR-005 of the application.
The NRC staff reviewed the general design of the package for completeness and accuracy and finds that the applicant adequately incorporated information related to the geometry, dimensions, materials, components, and relevant details of the major structural components of the DPR 200 transportation package. Therefore, the NRC staff finds that the information provided for the transportation package includes sufficient detail to demonstrate compliance with the design requirements of the SSR-6, and as required in paragraphs 809 and 810.
2.2 Lifting Attachments Paragraphs 608 and 609 in SSR-6, require that any lifting attachments on the package be designed such that it will not fail when used in the intended manner and if it fails, the package will still meet the other requirements in the Regulations. For transportation packages used in the United States, the design of lifting attachments must provide a minimum safety factor of three (3) against yielding. Submittals SR-060, DPR 200 USA Lifting Assessment, and SR-025, DPR 200 Lifting Safety Assessment, provide the analysis for the design of the DPR 200 lifting devices to demonstrate that they provide adequate margin of safety. Figures 1 and 2 in SR-033 illustrate these attachment points, and section 5.5 of SR-025 describes their material properties and design capacity.
For lifting and handling purposes, the DPR 200 package was designed with four eyes attached to the shield assembly, four eyes attached to the flask, and a single eye attached to the closure.
All these attachments are considered to be structurally part of the package and were evaluated in SR-060. The analysis concluded that a minimum safety factor of 6.63 is obtained for the lifting eyes located in the shield assembly when the maximum achievable angle of 80 degrees is reached between the multi-leg slings. The analysis concluded that a minimum safety factor of 3.46 is obtained for the welds used in the flask eyes when the maximum achievable angle of 90 degrees is reached between the multi-leg slings, and a safety factor of 18.74 was calculated for the weld in the enclosure eye. In addition to the lifting eyes, the pallet also includes channels to allow for lifting of the package using forklifts. When the forklift is used, the loads are 2
transferred directly through the pallet into the flask feet and via the fin welds into the flask. For this lifting method, SR-060 determined a minimum safety factor of 5.11 for the flask feet.
Based on a review of these analyses, the NRC staff determined that the lifting attachments will not fail when used because the calculated safety factors remained above the required safety factor of three (3.0) for all lifting device components used in the DPR 200 transportation package. Therefore, the NRC staff finds that the package meets the regulatory requirements in paragraphs 608 and 609 of SSR-6 for lifting attachments.
2.3 Tie-Down Devices Paragraph 638 in SSR-6 requires that any tie-down attachments on the package be designed so that the forces in those attachments shall not impair the ability of the package to meet the requirements in the Regulations. For transportation packages used in the United States, tie-down devices must be capable of withstanding a static force of 2 times the weight of the package in the vertical direction, 10 times horizontally in the direction of travel, and 5 times in the transverse direction.
As stated in the application, the DPR 200 package may be tied down during general transport using the same four lifting eyes set around the shield and chocks around the pallet. SR-061, DPR 200 USA Tiedown Safety Assessment, calculated the maximum stresses of the tie-down devices considering the static forces defined for the United States and determined that the stresses remained within the yield limits with a resultant safety factor greater than 1.0.
Based on a review of the analysis, the package structural integrity will be maintained during transport (provided that the tiedown angle and members remain as specified in the safety analysis report). Therefore, the NRC staff finds that the design of the tie-down devices meets the regulatory requirements in paragraph 638 of SSR-6 for tie-down devices.
2.4 Structural Analysis for the Transportation Package The applicant seeks to demonstrate compliance with the performance standards requirements from the Regulations by demonstrating the ability of the package to withstand the tests representative of NCT (paragraphs 719 thru 724 of SSR-6) and ACT (paragraphs 726 thru 730 of SSR-6). Specifically, paragraph 648 in SSR-6 requires the design of the package be able to prevent, after the tests: (a) loss or dispersal of the radioactive contents, and (b) more than a 20 percent increase in the maximum radiation level at any external surface of the package. In addition, paragraph 659(a) restricts the loss of radioactive contents to not more than 10-6 A2 per hour. Furthermore, paragraph 719 requires the transportation package be subjected to a free drop test, a stacking test, and a penetration test, preceded in each case by the water spray test to demonstrate the ability to withstand NCT. Additionally, paragraphs 727 and 728 of SSR-6 requires that the package be subjected to the cumulative effects of a mechanical test that consists of three different drop tests and a thermal test thereafter to demonstrate the ability to withstand ACT. Following these tests, the package needs to be subjected to a water immersion test.
The structural evaluation of the DPR 200 package was performed using a numerical model to analyze the different test criteria for NCT and ACT. A sensitivity analysis was performed, and the model was further validated using the test results from physical drops of a prototype.
SR-046, DPR 200/01 Drop Test Report, provides the results of these drops. For the stacking test, the applicant used numerical calculations, in lieu of testing, to demonstrate the packages 3
ability to maintain structural integrity during a stacking configuration. A summary of the NRC staffs evaluations of these testing and analyses is provided below.
2.4.1 Water Spray Test The applicant stated that the water spray testing was considered not applicable and was not performed because it will have no effect on the metal structure used for the package design.
The NRC staff reviewed the package design and finds that the water spray testing described in paragraphs 720 and 721 of the Regulations is not necessary since the effects of the water spray are negligible by design.
2.4.2 Drop Tests Paragraphs 722 and 727 of SSR-6 require that the DPR 200 transportation package be dropped onto a target so as to suffer maximum damage in the safety features of the package. For NCT, a free-fall drop distance of 0.9 m needs to be considered for packages with a mass greater than 5,000 kg but less than 10,000 kg. For ACT, a free-fall drop distance of 9 m needs to be considered concurrently with the cumulative effects of the other tests specified in the Regulations.
As summarized in section 6.7 of SR-033, the applicant performed a series of drop simulations considering various impact configurations to demonstrate compliance with the testing requirements from the Regulations for both the normal and accident conditions of transport. An explicit finite element software (i.e., LS-DYNA) was used to perform the drop simulations of the DPR 200 transportation package and to characterize its impact performance. These drop simulations included two drops from a 0.9 m distance (one upright and one inverted) to account for the NCT testing requirements, and two additional drop campaigns having different configurations to account for the ACT testing requirements. The first ACT simulation drop campaign consisted of seven different simulation drops from a 9 m distance using different package orientations, and the second ACT simulation drop campaign consisted of five drops from a 1 m distance using different package orientations. The drop test orientations were chosen so as to cause the maximum damage to the package. After the simulation drop campaigns, the applicant was able to conclude that neither containment nor shielding security were significantly challenged, and that the content remained contained within the package.
SR-029, DPR 200 Impact Safety Assessment, provides for the impact performance analysis performed for the DPR 200 transportation package using the explicit finite element software. A summary of the physical drop test results is also provided in SR-046.
Based on the review of the analyses and the drop test results, the NRC staff finds that the DPR 200 transportation package meets the applicable drop tests requirements in paragraphs 722 and 727 of SSR-6 for NCT and ACT.
2.4.3 Stacking Test Paragraph 723 of SSR-6 requires subjecting the DPR 200 transportation package to a load equal to the greater of the following to determine the maximum compression stress on the package: (a) 5 times the maximum weight of the package, or (b) 13 kilopascals (kPa) times the vertical projected area of the package.
As stated in the SR-031, DPR 200 Compression Test Assessment, option (a) was found to be the most conservative load design for the package. Therefore, considering a load that is 5 times the maximum weight of the package, the applicant calculated the maximum stresses due to a 4
stacking configuration for each of the components within the load path (i.e., top shield cones, top shield webs, connecting plates and welds, jacket and its base, flask foot, and the pallet).
The analysis demonstrated that the maximum stress in these components during a stacking configuration remains below the applicable shear, bending or compression stress limits of the component. Since the minimum factor of safety obtained for the most critical component resulted in 2.23, the applicant concluded that the DPR 200 package meets the regulatory requirements of the stacking configuration.
The NRC staff reviewed the analysis and test results submitted by the applicant and finds that the applicant has demonstrated that the package meets the regulatory requirements in paragraph 723 of SSR-6 for the stacking condition.
2.4.4 Penetration Tests Paragraphs 724, and 727 of SSR-6 require the DPR 200 transportation package be subjected to a penetration test targeting the center of the weakest part of the package so that, if it penetrates sufficiently far, it will hit the containment system. For NCT, a bar having 3.2 cm in diameter with a hemispherical end and a mass of 6 kg must be selected and dropped from a 1 m distance. For ACT, a 15 cm in diameter solid mild steel bar must be dropped from a 1 m distance. Tests effects must be considered concurrently with the cumulative effects of the other tests specified in the Regulations.
For the NCT, section 3.1 of SR-029 states that the penetration test specified in paragraph 724 of the Regulations must have no effect on the external structure. Therefore, the NRC staff reviewed the package design and noted that the minimum thickness of the structural steel plates should be sufficient to preclude the drop effect from the bar specified in the Regulations and, therefore, finds it acceptable. For ACT, the target was modelled as a rigid body with sharp edges to cause maximum damage when the packaged was dropped from a 1 m drop distance with a 25° angle. Although the components analyzed using the model resulted in some tearing at the outer surface of the components, the applicant concluded that neither containment nor shielding security were significantly challenged.
To assess the sensitivity of the model, a physical drop test was also performed by the applicant using a prototype angled to the same 25.1 degrees horizontally as the model. The prototype was dropped from 1 m distance onto a steel bar designed as specified in the Regulations (i.e., the bar had a diameter of 150 mm and a radius of 1-2 mm at top corners). The test concluded that the drop did not result in penetration of the jacket outer skin; no other damage was observed to the flask, the shield locking pin or the flask feet fasteners; and the content remained undamaged.
Based on a review of the analyses and test results, the NRC staff finds that the DPR 200 transportation package meets the regulatory requirements in paragraphs 724 and 727 of SSR-6 for the penetration test.
2.4.5 Water Immersion Test Submittal SR-040, DPR 200 Pressure, Thermal and Torque Stress Assessment, Revision 1, analyzed the flask wall and base by considering an external pressure equivalent to the package being immersed to a depth of 15 m (i.e., an external gauge pressure of 0.150 N/mm2 (or 150 kPa) as recommended in the Regulation). The calculated maximum stress that resulted was less than the design stress of the component, which resulted in a minimum safety factor of 2.06. The analysis demonstrates that the flask is not expected to be adversely affected when 5
immersed to a depth of 15 m. Therefore, the NRC staff finds that the regulatory requirements in paragraph 729 of SSR-6 are met.
2.4.6 Enhanced Water Immersion Test The SSR-6, paragraph 730, requires an enhanced water immersion test for Type B(U) packages containing more than 105 A2 material. However, the applicant stated that this requirement is not applicable to the DPR 200 package because the proposed contents are less than 105 A2. A review of SR-033 confirmed that the A2 value is below the threshold. Therefore, the NRC staff finds that it is not required to meet the regulatory requirements in paragraph 730 of SSR-6.
2.5 Evaluation of the Computer Model Design Validation The analysis of the DPR 200 package was performed using a numerical model (or finite element model) that subjected the package to the different impact tests stipulated in the Regulations as representative of NCT and ACT. To validate the numerical model, four physical drop tests were also performed using a single full scale prototype (or specimen) package that had the same material properties and mass attributes as the modelled/designed package. For the tests, the ACT test requirements were considered the bounding scenario and were performed targeting the components most likely to be damaged during impact to maximize the amount of damage to the structure. A summary of the physical drop test results is provided in SR-046.
Submittal FNC 61175/51032R, DPR 200 Container Assessment Finite Element Model Validation Report, provides for the evaluation performed during the model validation which compared the physical test results against the test results from the numerical model. A sensitivity analysis was also performed to assess the impact performance sensitivity of the model, and to demonstrate the adequacy of the parameters, variables and physical properties used for impact modeling. The results showed that the model is configured to replicate physical testing, and that it adequately captures the distribution of damage, the deformed shape, and trends in velocity-time histories.
The staff finds that the proposed methodology to analyze the transportation package has been validated and is in accordance with section VI of SSG-26, Advisory Material for the IAEA Regulations for the Safe Transport of Radioactive Material. Therefore, the proposed methodology of analysis is adequate to demonstrate compliance with the performance standards required in the Regulations.
2.6 Evaluation Findings
Based on a review of the statements and representations contained in the application, the NRC staff finds that the DPR 200 transportation package has an adequate design to withstand mechanical loads during NCT and ACT, and therefore, the package meets the Regulatory requirements of SSR-6. The staff recommends revalidation of the UK Certificate of Competent Authority GB/4120/B(U) (Rev.0) for import and export use.
3.0 THERMAL EVALUATION The purpose of the thermal review is to verify that the package design satisfies the requirements for the thermal evaluation under SSR-6. The staff reviewed the thermal properties of the materials used for the Model No. DPR 200 package and the description of the thermal analysis against the standards in SSR-6. A summary of the staffs review is provided below.
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3.1 Description of the Thermal Design The Model No. DPR 200 is designed to transport: Cobalt-60 high energy gamma radiation emitting sources, that are for the most part special form sources, the same material when it is no longer in conformance with its certification or when that certification has lapsed, and/or in bulk when its activity is greatly reduced, or feedstock sources which may or may not be special form. The DPR 200 is a Type B(U) package. The staff reviewed the following information related to the description of the thermal design of the DPR 200 from submittal R12920, Thermal Analysis of the DPR 200 Radioactive Materials Transport Container, Revision 1:
thermal material properties (section A.3) the descriptions of the thermal models (sections 2 and 3) the assumptions used in the thermal analyses (section 3) and the calculations and results from the thermal models for normal transport and accidental transport (section 4).
The applicant stated in sections 4 and 5 of SR-027, DPR 200 Thermal Safety Assessment, Revision 1 that for shipments of Cobalt-60 in special form the heat load limit is 3,546 Watts (W),
for shipments of Cobalt-60 not in special form the heat load limit is 3,392 W. To maintain the temperature at the surface of the package below 50 °C for air transport (the surface temperature will not exceed 47 °C as shown in section 6.5.1 of SR-027) the heat load limit is 500 W.
Because the surface temperature for air transport is below 50 °C, paragraph 619 of SSR-6 is met. The heat load limits for the Model No. DPR 200 are summarized in table 3.1 of this SER.
Table 3.1 Heat Load Limit for Model No. DPR 200 Allowable Content.
Contents Heat Load Limit, Watts (W)
- 1. 60Co (special form, up to 8.51 PBq) 3,546
- 2. 60Co (not special form, up to 8.14 PBq) 3,392
- 3. 60Co (for air transport, up to 1.20 PBq) 500 The staff reviewed sections 2, 3, 4, and A.3 of R12920, and determined that the applicant adequately described the thermal features of the DPR 200 package and its heat generation for the allowed contents described above and that this information is in alignment with the packages thermal evaluation. The DPR 200 package requires exclusive use conditions for content activities exceeding 1.20 PBq 60Co, as described in section 4.7 of SR-033.
3.2 Thermal Analysis and Boundary Conditions The applicant performed three-dimensional (3-D) analyses of the DPR 200 package using the computational fluids dynamics (CFD) thermal analysis code ANSYS CFX version 2019R1 to verify that the thermal design of DPR 200 package (under NCT and ACT) was in compliance with the regulatory safety requirements of SSR-6.
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The staff confirmed that a DPR 200 package loaded with contents as described in table 3.1 of this SER meets the requirements for thermal performance in SSR-6 for the air transportation of the radioactive isotopes based on the following information from R12920:
the package is subject to a hot ambient temperature of 38 °C for NCT (section 3.3) the initial conditions of the package during NCT are used for ACT (section 3.5, page 10) the package is exposed to 800 °C for a period of 30 minutes with the 800 °C temperature directly applied to package outer surface for ACT (section 3.5, page 10) and the package is exposed to a hot ambient temperature of 38 °C, natural convection, and solar insolation during the post-fire cool down (section 3.5, page 11).
3.3 Thermal Evaluation under Normal Conditions of Transport The applicant provided the predicted NCT maximum temperatures of the package components; closure seal, vent seal, and drain seal; and package large grill outer surface in section 7.4 of SR-027. The applicant used the maximum heat load of 3,546 W for this analysis.
The staff reviewed the descriptions and the modeling calculations of the DPR 200 and the applicants evaluation of the thermal performance under NCT. The staff confirmed the following based on the applicants predicted temperatures provided in section 7.4 of SR-027, and the associated temperature limits provided in section 6.4 of SR-033:
The maximum temperatures of the closure seal, vent seal, and drain seal are within the upper and lower temperature limits of the seals, -48 °C to 200 °C.
The maximum temperatures of the spent fuel and containment boundary are within the upper and lower temperature limits of -200 °C to 800 °C.
The maximum temperature of the lead is below the melting point provided in section 6.2.3 of SR-033.
The staff concluded that the containment will be maintained under thermal NCT.
For the DPR 200 package under routine conditions (i.e., with a heat load up to 3,546 W, no solar insolation, 38 °C ambient) the maximum surface temperature of the package large grill outer surface is 78 °C, as shown in sections 6.5.3 and 6.5.4 of SR-033, which is above the maximum temperature of 50 °C required by the Regulations (paragraph 654 of SSR-6) and a heat shield, screen, or personnel barrier should be used to make the hot surface inaccessible.
Similarly, for the DPR 200 package under routine conditions, paragraph 655 of SSR-6 is met, because the outer surface is 78 °C and is below the maximum temperature of 85 °C required by the Regulations.
3.4 Thermal Evaluation under Accident Conditions of Transport The applicant performed an ACT thermal analysis for the DPR 200 package where the thermal model includes NCT initial conditions, and an 800 °C boundary condition applied to the package outer surface for a period of 30 minutes as described in section 3.5, page 10 of R12920. The applicant performed a post-fire cool down thermal analysis where the package is exposed to a hot ambient temperature of 38 °C, natural convection, and solar insolation as described in 8
section 3.5, page 11 of R12920. The applicant assumed an emissivity of 0.95 for all package outer surfaces, to represent surfaces covered by soot, and an absorptivity of 0.8, which meets the requirements of paragraph 728 of SSR-6. The applicant used the maximum heat load of 3,546 W for the ACT thermal analysis.
The applicant provided the predicted ACT maximum temperatures of the package components; closure seal, vent seal, and drain seal in section 7.4 of SR-027. The staff confirmed the following based on the applicants predicted temperatures provided in section 7.4 of R12920, and the associated temperature limits provided in section 6.4 of SR-033:
The maximum temperatures of the closure seal, vent seal, and drain seal are within the short-term upper temperature limit of the seals, 290 °C.
The maximum temperatures of the spent fuel and containment boundary are within the upper temperature limit of 800 °C.
The maximum temperature of the lead is below the melting point provided in section 6.2.3 of the document entitled, SR-033.
The staff concluded that the containment will be maintained under thermal ACT.
The staff reviewed the tables and figures related to the ACT temperature distributions from R12920. The applicant also benchmarked the ACT thermal model predicted temperature results against the temperatures measured on a prototype with a reduced internal heat load, as described in section 3.17 of R12920. The applicant concluded that the model generally predicted package and contents temperatures accurately, any differences there were overstated the temperatures slightly, which indicated the applicants thermal model was conservative; based on the staffs review of section 3.17, the staff finds this to be acceptable.
3.5 Maximum Normal Operating Pressure As described in section 6.6.1 of R12920, the applicant calculated the maximum normal operating pressure (MNOP) to be 192 kPa gauge for routine and normal conditions, and 204 kPa gauge for accident conditions. The applicant described in section 6.6.1 of R12920 that the pressure in the containment system will arise from the effect of elevated temperature on the constant volume of the enclosed gas. The applicant continued to describe that the NCT and ACT pressures have no adverse effect on the spent fuel contents, and that the stresses generated by pressure differentials have no adverse effect on the containment system; based on the staffs review of section 6.6.1 of R12920, the staff finds the applicants conclusions to be acceptable.
3.6 Evaluation Findings
Based on review of the statements and representations in the application for the DPR 200 package, the staff concludes that the applicant adequately described and evaluated the thermal design of the DPR 200 package. Therefore, the package meets the thermal requirements of SSR-6. The staff recommends revalidation of the UK Certificate of Competent Authority GB/4120/B(U) (Rev.0), dated April 1, 2022, for the DPR 200 package, and suggests including the following condition:
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The surface of the package shall be below 50 °C prior to shipment. For contents greater than 1.20 PBq, the package must include a personnel barrier to limit the surface temperature to below 50 ºC.
4.0 CONTAINMENT EVALUATION The objective of this containment evaluation review is to verify that the DPR 200 package design satisfies the containment requirements of SSR-6 (2018) for routine, normal, and accident conditions of transport.
The applicant provided a report on the overall performance of the DPR 200 package in SR-033 and the containment analysis for the DPR 200 package in the document SR-030, DPR 200 Containment Safety Assessment, Revision 1. The staffs technical review of these analyses and other relevant documents provided by the applicant is described below.
4.1 Description of the Containment Design The applicant provides a general description of the package design in section 3.1.1 of SR-033, as well as a review of the containment system performance in section 6.3 of the same report.
A description of the package contents and the containment system of the package is provided by the applicant in section 2 of SR-030, which states:
The DPR 200 is intended to carry encapsulated metallic 60Co [Cobalt-60]
both as Special Form (SF) material and as sealed sources (non-SF). SF material by virtue of its impact and thermal qualification may be considered a part of the containment system (para 642, SSR-6) but non-SF material requires the flask to assure containment of potentially powdered material.
The description in section 2 further describes the containment boundary as the flask and the closure internal surfaces and states:
The flask and closure are also equipped with ports for introducing tracer gas in order [that] the containment boundary (the flask and closure internal surfaces) may be routinely leak tested.
The description in this section further states that the two test ports provided ensure the entire containment boundary may be tested.
Figure 1 of SR-030 (reproduced below) provides a visual depiction of the containment system components.
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The applicant states that, in accordance with SSR-6 paragraph 662, no valves or pressure relief devices are incorporated into the package design.
Further design details of the package related to the containment performance are provided in section 5, Design Details, of SR-030.
4.2 Pressure The applicant reports, in section 5.4, Internal Pressure, of SR-040, the calculated internal pressures of the flask cavity for routine, normal (MNOP), and accident conditions as:
194 KPa (gauge) (28.1 psig), 194 KPa (28.1 psig) and 206 KPa (29.8 psig), respectively. The pressures calculated by the applicant for all transport conditions are well below the package design requirement of 700 KPa (100 psig).
4.3 Containment Under Routine Conditions of Transport The applicant provided an assessment of the containment performance for routine transport conditions in section 6 of SR-030. The applicant discusses the performance of the containment boundary under cold temperature (-40 °C) conditions, the thermal and chemical environments encountered by the package, as well as the potential effects of radiation exposure.
In SR-030 of section 6.7, Leaktightness, the applicant indicates that the package will meet a leakage criterion (helium leak rate) of 10-6 Pa*m3/s1, which the applicant notes is described in 1 Although not mentioned in the application, the ANSI standard N14.5 For Radioactive Materials Leakage Tests on Packages for Shipment provides the definition of leaktight for a package containment boundary and is the only standard that does so. This is the only definition for leaktight that is recognized by the NRC.
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IAEA SSG-26, paragraph 659.13 as being sufficient to retain even the smallest particle size powder. The applicant therefore uses this criterion for testing of the containment boundary and the seals of the package. During the review the staff noted that the leakage rate stated in the application was greater than the leaktight criteria of American National Standards Institute (ANSI) N14.5, which defines leaktight as demonstration of a leakage rate less than or equal to 1x10-7 ref*cm3/s, which is equivalent to 10-8 Pa*m3/s. The staff has proposed a certificate condition to include this criterion for the DPR 200 package.
In SR-030 of section 6.8, Seal Compression, the applicant provides an extensive discussion on the performance of the Parker FKM elastomeric O-ring seals (V1289) used in the package, specifically focused on compression of the seal while it is installed in the package at closure of the package for transport and during routine transport.
The applicant calculates, in SR-030 section 6.8 (a), the minimum compression of the seals (using the Minimum Seal Cross-Section (mm), Maximum Groove Depth (mm) and seal Compression (Cmin)) and, in section 6.8 (b), the compression set of the seal (time/temperature phenomenon that reduced seal compression) as well as, in SR-030 section 6.8 (c), the impacts of any potential thermal distortion of the seal mating surfaces caused by thermal gradients in the flange of the package.
Finally, in SR-030 section 6.11 the applicant states that the seals on the package are leak tested before any non-Special Form (non-SF) shipments and that the seals on the package are replaced at a maximum internal of 21 months and that the seals are leak tested after replacement.
The applicant provides a summary of their findings for routine conditions of transport in a table in SR-030 section 6.12.
4.4 Containment Under Normal Conditions of Transport The applicant provided an assessment of the containment performance for NCT in section 7 of SR-030. The applicant discusses the performance of the containment boundary under the thermal and chemical environments encountered by the package under NCT. The applicant has applied the seal assessments from section 6 of SR-030 to NCT.
The applicant addresses the potential effects of NCT impacts in SR-030 section 7.3 on the performance of the containment system (boundary) and seals. The applicant indicates that the impact modelling for accident conditions bounds those for normal conditions and that the strain levels in the containment boundary components are within the limits as well as no observable physical damage or plastic deformation (permanent distortion in the applicants words) in the closure that would lead to a relaxing of seal compression beyond what is allowed.
The applicant provides a summary of their findings for NCT in a table in section 7.4 of SR-030.
4.5 Containment Under Accident Conditions of Transport The applicant provided an assessment of the containment performance for ACT in section 8 of SR-030. The applicant discusses the performance of the containment boundary under the thermal environments encountered by the package under ACT and has specifically investigated the thermal distortion and seal compression aspects of the package during ACT in section 8.2 of SR-030.
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Regarding thermal distortion, the applicant calculates that any potential distortion of the edge of the closure flange of the package would lead to significantly less than the minimum allowable loss of seal compression. Therefore, the applicant concludes thermal distortion of the flange due to temperature gradients would not affect the capability of the seals to maintain their compression in the seal grooves in which they are installed.
The applicant, in section 8.3 of SR-030, addresses the potential effects of ACT impacts on the performance of the containment system (boundary) and seals. The applicant briefly mentions SR-029, and notes that the results presented in this report demonstrate that the strain levels in the containment boundary components are within the limits and that the results further indicate no physical damage or permanent distortion of the closure, or its fixings, or of either the drain or vent plug or their housings that could potentially lead to a relaxing of seal compression beyond what is allowed.
The applicant did note that the impact analysis indicated momentary closure flange separation due to an impact shock wave that passed through the package body, creating a momentary (14 msec) gap of 0.78 mm (0.03 inch), which has closed by the end of the analysis. The applicant maintains that there is no possibility of a significant release given the limited duration and the minute magnitude of the gap. The NRC staff generally agrees with this assessment.
The applicant, in sections 8.4 and 8.5 of SR-030, examine maximum seal compression and groove fill, respectively, for all containment boundary seals. The applicant reports a maximum seal compression of 29.9 percent and a maximum groove fill of 89 percent, this narrowly meets the reported acceptance criteria of 30 percent and 90 percent, respectively.
The applicant provides a summary of their findings for ACT in a table in section 8.6 of SR-030.
4.6 Containment Evaluation In section 9, Conclusions, of SR-030 the applicant provides a summary of their findings relating to the ability of the DPR 200 package to meet its design requirements and comply with the regulatory requirements related to containment performance presented in the relevant paragraphs of SSR-6 listed for routine, normal and accident conditions of transport. The table below summarizes the applicants findings.
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Summary of Applicant Findings (Section 9 of Report SR-030)
Requirement SSR-6 Paragraph Routine Conditions of transport For packages to be transported by air, containment integrity 620 maintained for ambient temperatures from -40 °C to 55 °C The containment system will remain securely closed an cannot be 641 opened unintentionally during transport The containment system may be securely closed independent of any 643 other part of the package The containment system is suitable for chemical, thermal and 644 radiation environment in which it will be operating for the service life of the package.
No loss or dispersal of radioactive contents; loss of radioactive 648 & 659 (a) contents is limited to not more than 106A2 per hour when the package is subject to NCT testing.
Permitted activity release from package does not depend on filters or 661 a mechanical cooling system.
The package does not feature a pressure release system that would 662 release radioactive material to the environment under NCT Inspection and Maintenance procedures found in Section 3 of N/A Procedure OP-010 ensures containment system will continue to be effective over the service life of the package.
Minimum seal compression for all the seals on the package meet the N/A manufacturers design code.
Normal Conditions of transport The containment system is suitable for chemical, thermal and 644 radiation environment in which it will be operating for the service life of the package.
Strains levels in the containment boundary and closures for NCT are N/A bounded by accident condition strains.
Accident Conditions of transport Accident conditions of transport would not cause a release of 659 (b) greater than 10A2 for krypton-85 and not more than A2 for all other radionuclides radioactive contents in a period of one week from the package.
Strain levels in the containment boundary and closure reported in SR- N/A 029 are within design limits No permanent gaps form between the closure flange and flask body N/A when exposed to accident conditions Maximum seal compression conforms to manufacturers design N/A Maximum groove fill conforms to manufacturers design N/A 14
Based on the review of the statements and representations in the application, the staff concludes that the DPR 200 containment design has been adequately described and evaluated and that the package design meets the containment requirements of SSR-6. Hence revalidation is recommended based on the containment performance of the package.
As part of the preparation for transport, the package, when loaded with non-special form contents, should be leak tested to a maximum allowable helium leak rate criteria of 1.0x10-8 Pa-m3/sec, in compliance with ISO 12807. This specific condition is being recommended for approval of this application and use of the DPR 200 package.
5.0 CRITICALITY This package does not include transportation of any fissile material. Thus, no criticality evaluation was performed.
6.0 SHIELDING The staff reviewed the application to ensure that the shielding is adequate to meet the radiation level requirement within SSR-6 for protecting people and the environment, for this type of package. Specifically, staff verified compliance with the requirements of paragraphs 523, 526, 527, 648(b), and 659(b)(i).
6.1 Description of the Shielding Design The DPR-200 package consists of the following components: a lead-shielded, stainless-steel flask mounted on a pallet and protected from heat and impact by the top shield and jacket. The flask is an upright, cylindrical fabrication with the closure at the top. The package consists of a lightweight stainless-steel basket which can hold up to 70 pins in 4 concentric rings. The basket is then surrounded by lead bulk shielding subsequently surrounded by a layer of steel cladding, heat dispersion fins and a steel package jacket. A bent drain tube lies in the base of the package, with a steel-clad lead shield plug to cap the package. To prevent the migration of particulates past the shielding, there is a filter at the base of the cavity and a spring gasket at the top under the closure. DPR-200 has been developed for the transport of Cobalt-60 radioisotopes.
6.2 Evaluation Method The applicant considered only a single loading configuration of the Cobalt-60 pins for energy deposition calculation for dose rates calculations. The dose rates field around the package was numerically modeled using the Monte Carlo N-Particle (MCNP) code and the results cross-checked using the Attila discrete ordinate code.
6.2.1 Package Modeling The applicant used package arrangement information including dimensions from a 3D computer aided design (CAD) file and 2D engineering drawings. Sections and details used in the dose rate calculations are shown figures 2-5 of NT02204-SYN-TRANS-R02I2_NPM, Dose Rate Analysis for the STERIS DPR 200 Transport Package.
The applicant simplified the model to remove unnecessary detail, such as nuts, bolts and lifting hooks, etc. These were judged to provide little shielding and hence removal of these parts 15
would not adversely affect the dose rates. Although an insulation blanket exists between the package and the lead shielding, it is unlikely to affect the dose rate or the energy deposition calculations therefore it was removed from the model.
The applicant performed dose rates calculations around the package with the body made up of carbon steel instead of stainless steel. The staff found this approach acceptable since the density of carbon steel is slightly less than that of stainless steel and this component only makes up a fraction of the overall package shielding.
6.2.2 Source Modeling The applicants model consists of a minimum number of sources, 14 pins, in every other position, around the outermost ring of the basket only, with the same activity in all positions, and a total activity of 7.4 PBq (200 kCi). The sources are evenly distributed around the outer basket ring as required by the operating instructions. Thus, this configuration minimizes self-absorption in the contents and maximizing the radiation output. Modelling was based on 7.40 PBq contents so the results were scaled up in direct proportion for 8.51 PBq.
The applicant removed non-shielding components (e.g., fasteners, fins, grilles, etc.) from the model as they would have no effect on the results. The applicant only considered gamma radiation. The NRC staff found this approach acceptable because Cobalt-60 produces both gamma and beta radiation, and the interaction of the radiation with the thick shielding of the transport package means that the dose rates will be dominated by gamma radiation rather than the beta.
6.2.3 Flux-to-Dose Rate Conversion Factors The applicant used flux-to-dose conversion factors from the International Commission on Radiological Units and Measurements (ICRU) 57 Standard. This standard is not comparable to American Nuclear Society/American National Standard Institute (ANS/ANSI)-6.1.1-1977 conversion factors and NRC would not accept it for domestic package shielding analyses since ICRU 57 uses a model of the human body which only counts radiation interactions within specific tissues of the body, which unconservative allows other tissues to provide some amount of shielding. Those interactions are also influenced by the orientation of the body vs. the radiation source (i.e., whether the source is behind the body or in front of the person of off to one side of the person). Thus, it will be non-conservative when compared against ANS/ANSI-6.1.1 (1977), as this standard counts each tally in tissue, regardless of organ or location. Additionally, Part 71 (and the SSR-6) radiation level limits are in terms of dose equivalent and not the terms for which conversion factors such as ICRU 57 would be.
NRC staff performed confirmatory analysis using MicroShield, Version 12.14, with the ANS/ANSI 6.1.1 standard. It showed that the package radiation levels are still significantly below the limits, and so the staff finds assurance that the radiation level limits will not be exceeded. Thus, for this package and its contents, NRC staff accept it for domestic shielding analysis.
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6.3 Maximum Dose Rates 6.3.1 Normal Conditions of Transport (NCT)
Maximum dose rates are presented in section 5.2.1 of SR-028, DPR 200 Shielding Safety Assessment. Dose rates around the prototype DPR 200 were surveyed with 2.70 PBq Cobalt-60 and the results are presented in section 5.2.2 of SR-028.
The calculated dose rate at 1m from any surface does not exceed 43.8 Sv/h. The minimum margin of safety is 128 percent.
The calculated conveyance surface dose rate does not exceed 1.1 mSv/h. The minimum margin of safety is 82 percent. The calculated dose rate 2m from a conveyance does not exceed 48 Sv/h. The minimum margin of safety is 108 percent.
The extreme case (zero self-absorption in the sources) would increase dose rates by 27 percent, however this would not challenge the margins above.
The minimum manufacturing lead density of 99.5 percent gives a maximum potential increase in dose rates of 7.5 percent, however this increase has no significant effect on the margins above.
The staff noted that the dose rates from the direct measurements show broad agreement with the calculated dose rates. There are two exceptions near the top of the package and at the drain point, however, the safety margins are such that there is no likelihood of the design criteria being exceeded.
As a result, staff finds reasonable assurance the DPR-200 package meet the does-rate requirements established in the IAEA regulations.
6.3.2 Accident Conditions of Transport (ACT)
The applicant performed a numerical simulation of Drop test I in Section 5.4.1 of SR-028 as follows:
a) Upright: the center of activity to surface distance, 868 mm, is reduced by 177 mm to 691 mm. This will increase the dose rate at 1m by approximately 22% to 47 SV/h.
b) Inverted: The center of activity to surface distance, 962 mm, is reduced by 182 mm to 780 mm. This will increase the dose rate at 1m by approximately 22% to = 10 SV/h.
c) Side: the center of activity to surface distance, 494 mm, is reduced by 103 mm to 391 mm. This will increase the dose rate at 1m by approximately 15% to 42 SV/h.
The applicants modelling demonstrates no permanent strain in the shielding, its casings, or its fasteners or in the position of its contents from Drop II. There is permanent deformation in the pallet, jacket or top shield depending on the test orientation, but nothing that could affect the dose field at 1m.
Staff evaluated the effects of accident conditions on the package and found reasonable assurance the package meets the requirements of SSR-6. The only test to have any significant effect on dose rates at 1m is Drop I, however the numerical analysis demonstrates the DPR 200 17
remains within its design criteria and dose rates will rise by no more than 22 percent which is still significantly below allowable limits. The applicant also showed the target material meets the requirements to be determined special source under SSR-6. As a result, staff finds reasonable assurance that any effects on the targets would not result in significant changes from the configuration evaluated by the applicant.
6.4 Evaluation Findings
Based on a review of the statements and representations in the DPR-200 package application and as discussed above, the staff has reasonable assurance that the DPR-200 package meets the requirements in paragraphs 523, 526, 527, 648(b), and 659(b)(i) in SSR-6. The staff recommends revalidation of UK Certificate of Competent Authority GB/4120/B(U) (Rev.0).
7.0 MATERIALS EVALUATION The purpose of the materials evaluation is to verify that the performance of the materials used to fabricate the package meets the regulatory requirements of SSR-6. A summary of the staffs review is provided below.
7.1 Description DPR 200 is designed to ship high energy gamma sterilization sources (Cobalt-60) as a Type B(U) package in a Special Form (SF). In addition to SF, it is also designed to ship the same material when it is no longer in conformance with its certification or when the certification has lapsed and/or in bulk when its activity is greatly reduced or feedstock sources which may or may not be SF. This package is transported by road, rail, sea and air, however maximum radioactivity requirements are set based on mode of transportation and content. This package does not include transportation of any fissile material. Packaging and fabrication materials only attenuate the emitted gamma and beta radiation.
The staff finds the information provided is sufficient to demonstrate compliance with the SSR-6, Paragraph 809(a).
7.2 Materials Codes and Standards DPR 200 consists of a lead-filled stainless-steel flask mounted on a galvanized carbon steel pallet and is protected from heat and impact by a painted carbon steel shield assembly where lead is the primary shielding material. The flask is an upright cylindrical fabrication closed with a removable shield plug at the top called the closure. The cavity has a drain and vent to allow pool operations along with vent plug and drain plugs with elastomer O-ring seals.
Body: Stainless steel GR 1.4307 to BS EN 10088-2 or BS EN 10088-3 Closure: Stainless steel GR 1.4307 to BS EN 10088-2 or BS EN 10088-3 Shield Assembly: carbon steels S460NL or S355NL to BS EN 10025-3 Pallet: Carbon steels S460NL to BS EN 10025-3 Closure bolts: Stainless steel A2 or A4-80 to BS EN ISO 3506-1 Flask bolts (at flask feet): Carbon steel Grade 8.8 18
Flask dowels: Stainless steel A2 or A4-80 to BS EN ISO 3506-1 Link pins: Stainless steel A2 or A4-80 to BS EN ISO 3506-1 The staff reviewed the material properties provided in the package and referenced in SR-033 and relevant cited BS EN standards. The mechanical and thermal properties are in compliance with the referenced BS EN code.
The staff reviewed the package description, general design, materials specifications and fabrication methods for completeness and accuracy and finds that the information provided is sufficient to demonstrate compliance with the SSR-6, Paragraph 809(b).
7.3 Engineering Drawings The applicant provided the package drawings in SR-001, DPR 200 Container Drawings List, Revision 8 and SR-005, DPR 201 Basket Drawings List, Revision 2. The drawings include parts lists with the material specifications and dimensions of each component. The drawings also detail the weld fabrication and examination requirements, references to the code and standards, and procedures as documented below in the staffs review of welding and non-destructive examinations (NDE) methods.
The staff reviewed the drawing contents with respect to SSR-6 requirements and confirmed that the drawings provide an adequate description of the design, specifications of materials and fabrications requirements. Therefore, the staff finds the information provided is sufficient to demonstrate compliance with the SSR-6, Paragraph 809(b).
7.4 Content Reactions Special Form contents are sealed in capsules approved as SF and the stainless-steel flask cavity is dry and back filled with inert gas as outlined in OP-010, DPR 200 Operating and Maintenance Instructions, section 2.3.2.1 and 2.3.2.2. Non-SF contents are sealed in welded capsules and the stainless-steel cavity is dry and backfilled with an inert gas. In each case, the possibility of corrosion and or radiolysis is eliminated.
The staff finds the information provided sufficient to demonstrate compliance with SSR-6, Paragraph 644.
7.5 Radiation Effects The only components affected by radiation or heat are seals which are routinely replaced as stated in OP-010 section 3.2.
The staff reviewed the information provided and concludes that the information provided is sufficient to demonstrate compliance with the SSR-6, Paragraphs 614 and 653.
7.6 Bolting Material Closure bolts are either type 304 or type 316 austenitic stainless-steel material. Austenitic stainless steels have exceptionally high toughness and ductility and strain hardening capacity.
As a result, brittle fracture is not a concern. Brittle fracture mainly affects several types of ferritic steels which are less ductile and have lower fracture toughness. In addition, closure and pallet fasteners are routinely inspected and replaced as necessary per OP-010 section 3.2.
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The staff has reviewed the provided information and finds the information is sufficient to demonstrate compliance with SSR-6, paragraph 613.
7.7 Seals The staff also reviewed the RC27870, Determination of Loss of Seal Integrity on Cooling, on FKM O-rings ability to provide low temperature containment seal, which meets the requirements of SSR-6, paragraph 620. Seals have acceptable properties to meet the design and normal conditions of transportation. The effects of heat on containment seals are also addressed in SR-033 section 6.5.8, as these are the only components that could suffer from thermal degradation over time. All other components of the package are metal and are unaffected by temperatures of normal conditions of transport. The seals are limited to a maximum service life of 21 months as described in section 3.2.1 of OP-010 to ensure continued performance. Seals are inspected before each use per OP-010 section 3.1 and are replaced when necessary. The criterion for replacement is based solely on the condition of the item and not the maximum service life.
The staff has reviewed this information and concludes that the information satisfies the requirements of SSR-6, paragraph 653.
7.8 Weld Specification and NDE Methods The applicant provided welding and NDE specifications in SP-001, Welding Specification, which establishes controls for welding, brazing, soldering and associated NDE operations. It also provides requirements for welding, brazing, soldering, procedures, consumables, and welder performance qualification. In addition, it details NDE methods and acceptance criteria by relevant BS EN code. Furthermore, it requires that all welds, brazing, soldering and associated NDE operations must comply with the requirements of the relevant BS EN code.
The staff has reviewed the provided information and finds the information is sufficient to demonstrate compliance with SSR-6, paragraph 809(b).
7.9 Galvanizing The applicant provided specifications for galvanizing carbon steel components of the packaging in SP-002, Finishing Specification. Carbon steel surfaces are hot dip galvanized in accordance with BS EN 1461, and Zinc plating by means of electroplating or passivation is achieved in accordance with BS EN ISO 2082, Zn-3.
The staff has reviewed the provided information and finds the information provided sufficient to demonstrate compliance with SSR-6, paragraph 809(b).
7.10 Evaluation and Findings Based on a review of the statements and representations in the application for the DPR 200 package with Type B(U) content, the staff finds that the applicant adequately described and evaluated the materials performance of the DPR package, and these are acceptable.
Therefore, the staff concludes that the DPR package meets the materials requirements of SSR-6.
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8.0 QUALITY ASSURANCE EVALUATION The purpose of the quality assurance (QA) review is to verify that the proposed changes to the package design meet the requirements of SSR-6.
8.1 Staffs Evaluation of the Quality Assurance Program The applicant developed and described a QA program for activities associated with transportation packaging components important to safety. Those activities include design, procurement, testing, operation, maintenance, and use. The applicants description of the QA program (i.e., management system and compliance assurance programs) complies with the requirements of the current edition of BS EN ISO 9001:2015, applicable to the design and procurement of containers for transport of radioactive material (Certificate of Registration No. FS 712830), which satisfies the requirements of the applicable requirements in SSR-6. The staff finds the QA program description acceptable, since it allows implementation of the associated QA program for the design, procurement, testing (containment boundary, seals, shielding, and pressure), operation, maintenance, and use as defined within Operational Procedure OP-010.
The staff finds, with reasonable assurance, that the QA program for the DPR 200 transportation packaging:
- a. meets the requirements in SSR-6, and
- b. encompasses the controls applied to all packaging design and procurement activities as well as operations and maintenance controls, as appropriate, to ensure that the package will allow safe transport of the radioactive material authorized in this approval.
8.2 Evaluation Findings
Based on review of the statements and representations in the Model No. DPR 200 package application and as discussed in this SER section, the staff has reasonable assurance that the package meets the requirements in IAEA SSR-6, 2018 Edition.
9.0 CONDITIONS Specific limitations and conditions are specified for approval of this application and use of the DPR 200 package. The following limitations and features are listed here as recommended conditions of approval:
Condition 1: The surface of the package shall be below 50 °C prior to shipment. For contents greater than 1.20 PBq, the package must include a personnel barrier to limit the surface temperature to below 50 ºC Condition 2: As part of the preparation for transport, the package, when loaded with non-special form contents, should be leak tested to a maximum allowable helium leak rate criteria of 1.0x10-8 Pa-m3/sec, in compliance with ISO 12807.
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10.0 CONCLUSION
Based on the statements and representations presented in the SAR and supplemental information, the staff agrees that the package meets the standards in IAEA Safety Standards SSR-6, 2018 Edition. The staff recommends that DOT revalidate United Kingdom Certificate of Approval No. GB/4120/B(U), Revision 0, for import and export use.
Issued with letter to R. Boyle, U. S. Department of Transportation.
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ML23059A223; ML23059A225 OFFICE NMSS/DFM/STLB NSIR/DPR NMSS/DFM/IOB NMSS/DFM/NARAB JGoodridge NAME NDevaser ND ELove EL ASotomayor-Rivera AS WWheatley for WW DATE Mar 1, 2023 Mar 6, 2023 Mar 6, 2023 Mar 7, 2023 NMSS/DFM OFFICE NMSS/DFM/MSB NRR/DEX/ESEB NMSS/DFM/CTCFB
/CTCFB NAME OKhan OK JLopez JL CBajwa CB JIreland JI DATE Mar 8, 2023 Mar 7, 2023 Mar 21, 2023 Mar 14, 2023 OFFICE NMSS/DFM/IOB NMSS/DFM/CTCFB NMSS/DFM/MSB NMSS/DFM/CTCFB NAME ARivera-Varona AR JPiotter JP TBoyce TB DMarcano DM DATE Mar 23, 2023 Mar 21, 2023 Mar 21, 2023 Mar 21, 2023 OFFICE NMSS/DFM/STLB NAME YDiaz-Sanabria YD DATE Mar 23, 2023