MOX Fresh Fuel Packaging: Status of Full Scale Prototype Testing

Packaging Technology, Inc. is designing the Mixed Oxide (MOX) Fresh Fuel Package (MFFP) for Duke Cogema Stone & Webster (DCS). The package is unique because of weight and size constraints, having a relatively large payload to package weight ratio. The package has a containment shell, that utilizes high strength stainless steel to optimize the payload relative to the total weight available, protected at the ends by impact limiters. Because of the unique design, full scale prototype impact testing is scheduled for mid-2003. Engineering testing on key design elements, and certification test planning have been completed. Long lead material has been procured for fabrication of the prototype.

Electrochemical Behavior of Alloy 22 in 5 M CaCl2

The corrosion resistance of Alloy 22 (UNS No. N06022) was studied in 5 M CaCl2 electrolyte at various temperatures. Potentiodynamic polarization was used to examine the electrochemical behavior and measure the key potentials. Alloy 22 was found to be susceptible to localized corrosion in this high-chloride [10 M Cl−] environment at temperatures as low as 60°C.

Strain Gage Test Results of Band-Type Locking Rings for a Typical Drum Type Radioactive Material Package

Band type closure rings are commonly used for securing the drum lid on radioactive material packages of lower weight classifications. Lid installation is achieved by placing the band around the perimeter of the lidded drum and tightening the single bolt in stages until a designated torque value is obtained. The band is subjected to heavy rapping with a soft hammer during installation to equilibrate the band strains around the drum perimeter. The study described here investigated the strain distributions in the band throughout the installation process. The results show that a uniform strain distribution is achieved during installation and that the hammering of the band aids in achieving the uniform distribution. The results of the strain levels after the drop test indicate that the locking rings maintain some pre-tension, even after severe targeted drops that crush a portion of the drum top.

Response of Conventional Ring Closures of Drum Type Packages to Regulatory Drop Tests With Application to the 9974/9975 Package

DOT, DOE and NRC Type A and Type B radioactive material (RAM) transport packages routinely use industrial or military specification drums with conventional clamp ring closures as an overpack. Considerable testing has been performed on these type packages over the past 30 years. Observations from test data have resulted in various design changes and recommendations to the standard drum specification and use, enhancing the reliability of the overpack. Recently, performance of the 9975 conventional clamp ring closure design was questioned by the DOE Regulatory Authority. This paper highlights the observations of recent 9974 and 9975 package testing that led to redesign of the 9975, replacing the standard clamp ring closure with a bolted flange closure. In the course of this review and redesign effort, 18 package designs and approximately 100 Hypothetical Accident Condition (HAC) drops of various size and weight drum packages were evaluated. A trend was observed with respect to overpack lid failures for packages utilizing conventional ring closure. Based on this trend, a limit on the ratio of the internal weight to total package weight was identified, beyond which clamp ring closure failure may be expected.

Recent Progress on the Standardized DOE Spent Nuclear Fuel Canister

The Department of Energy (DOE) has developed a set of containers for the handling, interim storage, transportation, and disposal in the national repository of DOE spent nuclear fuel (SNF). This container design, referred to as the standardized DOE SNF canister or standardized canister, was developed by the Department’s National Spent Nuclear Fuel Program (NSNFP) working in conjunction with the Office of Civilian Radioactive Waste Management (OCRWM) and the DOE spent fuel sites. This canister had to have a standardized design yet be capable of accepting virtually all of the DOE SNF, be placed in a variety of storage and transportation systems, and still be acceptable to the repository. Since specific design details regarding the storage, transportation, and repository disposal of DOE SNF were not finalized, the NSNFP recognized the necessity to specify a complete DOE SNF canister design. This allowed other evaluations of canister performance and design to proceed as well as providing standardized canister users adequate information to proceed with their work. This paper is an update of a paper [1] presented to the 1999 American Society of Mechanical Engineers (ASME) Pressure Vessels and Piping (PVP) Conference. It discusses recent progress achieved in various areas to enhance acceptance of this canister not only by the DOE complex but also fabricators and regulatory agencies.

Transfer Cask Assembly: Onsite Transfer of K-Basin Fuel at Hanford

Packaging Technology, Inc. was awarded a contract for the design and fabrication of a unique 18.5-ton transportation system to be used on-site at Hanford, WA. Unique aspects include rectangular cask geometry, solid 7”-thick stainless steel construction, hinged lid with remotely operable quick release locking mechanism. The lid maintains shielding and material confinement integrity after hypothetical accident conditions, and is equipped with a hydrogen venting system. This paper presents how the project requirements were translated into a successful design, and includes a brief discussion of a confirmation test program.

Gamma Scan Confirmation of Lead Pour in a Type B Cask

Packaging Technology, Inc., a subsidiary of the French nuclear consortium Areva, has been tasked with manufacturing six RH-72B (72B) casks for the Department of Energy’s Carlsbad Operations Office. The 72B transportation cask will be used to transport remote-handled (RH) transuranic wastes to the Waste Isolation Pilot Plant (WIPP) located in New Mexico. Certification of each 72B cask includes a gamma scan of the cask lead shielded wall to verify that no significant voids form within the lead subsequent to the lead pour. Voids in the lead would be revealed as spikes in the gamma scan measurements. The radioactive isotope Iridium-192 was used as the source for the gamma scan measurements. To determine the maximum and minimum expected values for the cask gamma scan, a test fixture was required to be developed with flat plate shields that matched the maximum and minimum thicknesses of the steel-lead-steel cask wall. Design of the test fixture was a non-trivial exercise due to the influence of backscatter radiation, which if unshielded resulted in unreasonably high test fixture radiation doses. To properly shield the backscatter radiation, a collimator is required around the source. The measured dose rates using the test fixture is highly sensitive to the diameter of the collimator penetration, as a collimator penetration diameter that is too narrow results in artificially low dose rate measurements when compared to the cask measurements. To assist in the design of the collimator, the Monte Carlo N-Particle (MCNP) gamma transport code was employed. Using MCNP computer simulations, it was determined that a collimator diameter of 6 inches was sufficient to properly mimic the cask configuration.

A Standard for Storage and Transport of Damaged Spent Nuclear Fuel

The paper provides background on the Nuclear Regulatory Commission’s April 1984, Director’s Decision on failed and damaged spent fuel, DD-84-9. Examples of damaged fuel transports and the recently issued NRC interim staff guidance on damaged SNF, ISG-1, are discussed. These preliminary topics form the basis for discussion of the need, development and status of an American National Standards Institute standard, ANSI N14.33, for damaged spent fuel.

Test Results Using a Bell Jar to Measure Containment Vessel Pressurization

A bell jar is used to determine containment vessel pressurization due to outgassing of plutonium materials. Fifteen food cans containing plutonium bearing materials, including plutonium packaged in direct contact with plastic and plutonium contaminated enriched uranium oxide have been tested to date. As expected, minimal pressurization occurs and in some cases a slight depressurization has been observed. Linear extrapolation of the greatest pressurization observed in the bell jar to a typical drum shipping container (such as a 9975) has been performed. Pressurization from this particular can packaged for one year in a 9975 container is negligible.

Effect of Temperature and Humidity on Crush Strength of Cellulose Fiberboard Assemblies

Cane fiberboard is widely used as the impact absorption and thermal insulation material in overpacks for radioactive materials shipping packages. The study described here investigated the properties of cane fiberboard assemblies under environmental conditions important to radioactive materials packaging applications. Tests were performed for loading perpendicular and parallel to the planes of the fiberboard sheets for both slow and impact strain rates, at high and low temperature and at high and low humidity. Under high temperature and high humidity conditions, the stress/strain response of the assemblies was close to the response at ambient conditions. However, for low temperature and impact strain rate conditions for specimens loaded parallel to the planes of the fiberboard sheets, an initial stress spike was found. The cause of this transient, high, initial stress was determined to be the stiffening effect of the glue layers used to bond the fiberboard sheets together.