A Review of a Radioactive Material Shipping Container Including Design, Testing, Upgrading Compliance Program and Shipping Logistics

Ten years ago Atomic Energy of Canada developed a Type B(U)-85 shipping container for the global transport of highly radioactive materials. This paper reviews the development of the container, including a summary of the design requirements, a review of the selected materials and key design elements, and the results of the major qualification tests (drop testing, fire test, leak tightness testing, and shielding integrity tests). As a result of the testing, improvements to the structural, thermal and containment design were made. Such improvements, and reasons thereof, are noted. Also provided is a summary of the additional analysis work required to upgrade the package from a Type B(U) to a Type B(F), i.e. essentially upgrading the container to include fissile radioisotopes to the authorized radioactive contents list. Having a certified shipping container is only one aspect governing the global shipments of radioactive material. By necessity the shipment of radioactive material is a highly regulated environment. This paper also explores the experiences with other key aspects of radioactive shipments, including the service procedures used to maintain the container certification, the associated compliance program for radioactive material shipments, and the shipping logistics involved in the transport.

The French Approach Concerning the Protection of Shipping Casks Against Terrorism

The behavior of the casks used to ship nuclear material must be assessed for various normal and accidental situations. Though not explicitly required in the French regulations, the security of the casks must be studied in the context of potential loads resulting from terrorism. The “Institut de Radioprotection et de Suˆrete´ Nucle´aire” (IRSN), in order to provide the authority with important data, has conducted analyses. These analyses have been based on both experiments and numerical models for various casks and loads. These studies have been carried out using an approach consistent with that used for facilities.

Validation of the Isis-3D Computer Code for Simulating Large Pool Fires Under a Variety of Wind Conditions

The Isis-3D computational fluid dynamics/radiation heat transfer code was developed to simulate heat transfer from large fires. It models liquid fuel evaporation, fuel vapor and oxygen transport, chemical reaction and heat release, soot and intermediate species formation/destruction, diffuse radiation within the fire, and view factor radiation from the fire edge to nearby objects and the surroundings. Reaction rate and soot radiation parameters in Isis-3D have been selected based on experimental data. One-dimensional transient conduction modules calculate the response of simple objects engulfed in and near the flames. In this work, Isis-3D calculations were performed to simulate the conditions of three experiments that measured the temperature response of a 4.66-m-diameter culvert pipe located at the leeward edge of 18.9-m and 9.45-m diameter pool fires in crosswinds with average speeds of 2.0, 4.6 and 9.5 m/s. The measured wind conditions were used to formulate time-dependent velocity boundary conditions for a rectangular Isis-3D domain with 16,500 nodes. Isis-3D accurately calculated characteristics of the time-dependent temperature distributions in all three experiments. Accelerated simulations were also performed in which the pipe specific heat was reduced compared to the measured value by a factor of four. This artificially increased the speed at which the pipe temperature rose and allowed the simulated fire duration to be reduced by a factor of four. A 700 sec fire with moderately unsteady wind conditions was accurately simulated in 10 hours on a 2.4 GHz LINUX workstation with 0.5 GB of RAM.

Analysis of the Impact of a Tunnel Fire Environment on a Spent Nuclear Fuel Transportation Cask

On July 18, 2001, a train carrying hazardous materials derailed and caught fire in the Howard Street railroad tunnel in Baltimore, Maryland. Due to this accident, questions were raised about the performance of spent nuclear fuel transportation casks under severe fire conditions, similar to those experienced in the Baltimore tunnel fire. The U.S. Nuclear Regulatory Commission (NRC) evaluates the performance of spent fuel transportation casks under accident conditions. Title 10 of the Code of Federal Regulations Part 71 section 73(c)(4), (10 CFR 71.73(c)(4)) requires that transportation packages used to ship radioactive material must be designed to resist an engulfing fire of a 30 minute duration and prevent release of radioactive material to the environment. The staff of the NRC, in cooperation with the National Transportation Safety Board, the National Institute of Standards and Technology, Pacific Northwest National Labs and the Center for Nuclear Waste Regulatory Analysis, have undertaken an analysis to determine the thermal conditions present in the Howard Street tunnel fire, as well as analyze the effects that such a fire would have on a spent fuel transportation cask. This paper describes the analytic models used in the assessment and presents a discussion of the results.

Post Fire Transient Temperature Distribution in Drum Type Packages in the Absence of Heat Generation

This study investigates the temperature distribution in an idealized cylindrical package subjected to the HAC Fire transient, with no internal heat generation. Cases for overpack materials with thermal conductivity spanning two orders of magnitude are considered. The results show that the peak internal temperature is determined by the thermal conductivity of the overpack material, for this case. The thermal wave effect, where the interior temperature continues to rise after the end of the fire exposure, is present in all three of the test cases. For contents with no heat generation, the most desirable overpack materials would have low thermal conductivity and low heat storage capability. The study complements the parametric studies of effects of thermal properties on thermal response of packages which were previously reported.

Survey of Packaging Requirements for the Transport of Highly Hazardous Materials

Among hazardous materials those which are most dangerous fall into three categories: chemical, biological, and radioactive. The DOT hazard classes for these three categories are Hazard Class 2.3 (poisonous gases) and 6.1 (toxic substances) for chemical hazards, Hazard Class 6.2 (infectious substances) for biological hazards and Hazard Class 7 for radioactive material (RAM) hazards. The packaging requirements for chemical and biological hazards are outlined and compared with RAM packaging requirements. RAM packages are found to be able to withstand much more severe performance tests than packages for other, more lethal hazards.

Thermal Analysis and Test Results for the Overpack of a Typical Radioactive Materials Package

In the course of the development and certification of the 9975 Package, extensive thermal analyses were performed and the package subjected to the regulatory HAC thermal test. The results of the thermal analysis and materials tests of the cane fiberboard overpack material were evaluated in comparison with the package HAC thermal test results. The evaluation confirmed that the thermal analysis correctly predicted the performance of the 9975 in the HAC fire test. The post test examination revealed that the heat affected region of the Celotex® overpack correlated well with the calculated temperature distribution.

Gas Generation Measurements of Scrap Pu/U Materials Using a Bell Jar

A bell jar is used to determine containment vessel pressurization due to gas generation from plutonium/uranium materials. Seventy eight food pack cans containing plutonium and uranium oxide bearing materials have been tested to date. Minimal change in pressure (increase or decrease) occurred in fifty one cases, depressurization occurred in seventeen cases, and pressurization occurred in ten cases. Pressurization is considered linked to the presence of certain impurities such as magnesium oxide.

Repackaging of Two Bulged Crimp Sealed Cans Containing Plutonium Bearing Materials

Two cans containing plutonium bearing materials were found during radiography surveillance activities to be bulged. The cans had been stored in DOT 6M shipping containers at the Savannah River Site. The material in the first can (Item CZA96-179) was packaged can/bag/can configuration with the inner and outer cans being crimp sealed. The crimp sealed innermost can was clearly deformed from the radiography picture taken for surveillance purposes. This material had been stored in the shipping container since the mid 1970’s. The second can (Item 50014440) contained plutonium bearing material of a different origin. The material had been repackaged at the Savannah River Site in the mid 1990’s, and the repackaged can was stored in a 6M shipping drum. A special puncturing tool, which secured the can and allowed for a very controlled puncture of both outer and inner cans was used in a glovebox. The glovebox has a dry air system and an argon supply. The puncturing tool utilized a non-sparking punch and an argon purge. The cans were repackaged into filtered outer cans. A description of the puncturing tool, repackaging activities, and of the materials will be provided.

Corrosion Characteristics of Titanium Alloys in Multi-Ionic Environments

Yucca Mountain (Nevada) is designated as a high-level nuclear waste repository. The nuclear waste will be isolated by a series of engineered barriers. The metallic engineered barriers will consist of a double-wall container with a detached drip shield. The material for the external wall of the container is Alloy 22, a corrosion-resistant Ni-Cr-Mo alloy. Titanium grade 7 has been proposed for the drip shield. Ti alloys are highly resistant to all forms of corrosion due to the formation of a stable, protective and strongly adherent oxide film. The aim of this research was to characterize the general and localized corrosion behavior of Ti Gr 7, 16 and 12 in simulated concentrated ground waters. Welded and non-welded coupons were exposed for up to 5 years to the vapor and liquid phases of acidic and alkaline multi-ionic solutions at 60°C and 90°C. This paper describes the results obtained after approximately 2-1/2- to 5-1/2-year exposure to the testing electrolyte solutions. In general, the highest corrosion rate was obtained for Ti Gr 12; however, in all of the tested conditions, the corrosion rate was generally lower than 100 nm/yr. For all alloys, the highest corrosion rate was obtained in the concentrated alkaline solution.