Allen C. Smith

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.Copyright

Thermal Testing of Prototype General Purpose Fissile Packages Using a Furnace

The 9977/9978 General Purpose Fissile Package (GPFP) was designed by SRNL to replace the DOT 6M Specification Package and ship Plutonium and Uranium metals and oxides. Urethane foam was used for the overpack to ensure the package would withstand the 10CFR71.73(c)(2) crush test, which is a severe test for drum-type packages. In addition, it was necessary to confirm that the urethane foam configuration provided adequate thermal protection for the containment vessel during the subsequent 10CFR71.73(c)(4) thermal test. Development tests were performed on early prototype test specimens of different diameter overpacks and a range of urethane foam densities. The thermal test was performed using an industrial furnace. Test results were used to optimize the selection of package diameter and foam density, and provided the basis for design enhancements incorporated into the final package design.

Performance of a Drum Type Packaging with Urethane Foam Overpack Subjected to Crush and Other Regulatory Tests

In order to improve the melt rate of high level waste slurry feed being vitrified in the Savannah River Sites (SRS) Defense Waste Processing Facility (DWPF) Melter, a melter glass pump (pump 1) was installed in the DWPF Melter on February 10, 2004. The glass pump increased melt rate by generating a forced convection within the molten glass pool, thereby increasing the heat transfer from the molten glass to the unmolten feed cold cap that is on top of the glass pool. After operating for over four months, the pump was removed on June 22, 2004 due to indications that it had failed. The removed pump exhibited obvious signs of corrosion, had collapsed inward at the glass exit slots at the melt line, and was dog-legged in the same area. This lead to the pump being redesigned to improve its mechanical integrity (increased wall thickness and strength) while maintaining its hydraulic diameter as large as possible. The improved DWPF glass pump (pump 2) was installed on September 15, 2004. The impact of the new design on pump life, along with analysis of the glass pumps impact on melt rate in the DWPF Melter is discussed in this paper.

Dynamic Analysis of Radioactive Material Package With Clamp-Ring Closure

Separation of the closure lid from the drum-type radioactive material packages employing the conventional clamp-ring closure has been a safety concern. Currently, the evaluation of drum-closure separation problems resorts to expensive and time-consuming tests. Therefore, an analytical capability to predict drum-closure separation is desired. However, the conventional methods of dynamic analysis are not applicable to this subject. The difficulty of the problem mainly lies in solving the complicated preload stresses on the multiple contacted surfaces during claim-ring tightening and in integrating the preload results with the subsequent drop simulation. A technique has been previously proposed by Wu for the dynamic analyses of containers with locking-ring closures (Reference 1). This paper presents a refinement of the proposed technique and also extends the technique from the dynamic simulation of one single drop to the simulation of two sequential drops. The finite-element method with explicit numerical integration scheme is utilized to simulate both the closure bolt tightening process and the drop impact. The essential aspects of the proposed technique include: quasi-static simulation of clamp-ring tightening process; association of the floor motion with the package motion before the drop simulation starts; and creation of the package velocity before impact starts. To verify the proposed numerical technique, an analysis is performed for the 6M Package with a standard clamp-ring closure to simulate the following three sequential loading conditions: the preload caused by tightening the clamp ring; a NCT 4-foot drop; and a HAC 30-foot drop. The analytical results are compared with the results of the sequential NCT and HAC drop tests of a 6M Package with the standard clamp-ring closure. The test results have verified that the proposed numerical technique is capable of predicting the drum closure separation with respect to drop heights as well as the deformed shape of the package.Copyright

Drop Tests for the 6M Specification Package Closure Investigation

Results of tests of drum-type RAM packages employing conventional clamp-ring closures have caused concern over the DOT 6M Specification Package. To clarify these issues, a series of tests were performed to determine the response of the clamp-ring closure to the regulatory Hypothetical Accident Condition (9m) drop tests, for packages at maximum allowable weight. Three enhanced closure designs were also tested: the Clamshell, plywood disk reinforcement, and J-Clip. The results of the tests showed that the standard closure was unable to retain the top for both Center-of-Gravity-Over-Corner and Shallow Angle cases, for the standard package, at its maximum allowed weight. Similar results were found for packages dropped from a reduced height. The Clamshell design provided the best performance of the enhanced closures. It was concluded that the closure ring design employed on the 6M is inadequate to retain the top during the regulatory test sequence, for packages at the maximum allowed weight. For large heavy packages, the Center-of-Gravity- Over-Corner case is more challenging than the Shallow Angle case. The Clamshell design securely retained the top for all HAC test cases, and prevented formation of any opening which could compromise fire test performance.

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.Copyright

Development of Burn Test Specifications for Fire Protection Materials in RAM Packages

The regulations in 10 CFR 71 require that the radioactive material (RAM) packages must be able to withstand specific fire conditions given in 10 CFR 71.73 during Hypothetical Accident Conditions (HAC). This requirement is normally satisfied by extensive testing of full scale test specimens under required test conditions. Since fire test planning and execution is expensive and only provides a single snapshot into a package performance, every effort is made to minimize testing and supplement tests with results from computational thermal models. However, the accuracy of such thermal models depends heavily on the thermal properties of the fire insulating materials that are rarely available at the regulatory fire temperatures. To the best of authors knowledge no test standards exist that could be used to test the insulating materials and derive their thermal properties for the RAM package design. This paper presents a review of the existing industry fire testing standards and proposes testing methods that could serve as a standardized specification for testing fire insulating materials for use in RAM packages.

Performance of a Drum Type Packaging With Urethane Foam Overpack Subjected to Crush and Other Regulatory Tests

In order to improve the melt rate of high level waste slurry feed being vitrified in the Savannah River Sites (SRS) Defense Waste Processing Facility (DWPF) Melter, a melter glass pump (pump 1) was installed in the DWPF Melter on February 10, 2004. The glass pump increased melt rate by generating a forced convection within the molten glass pool, thereby increasing the heat transfer from the molten glass to the unmolten feed cold cap that is on top of the glass pool. After operating for over four months, the pump was removed on June 22, 2004 due to indications that it had failed. The removed pump exhibited obvious signs of corrosion, had collapsed inward at the glass exit slots at the melt line, and was dog-legged in the same area. This lead to the pump being redesigned to improve its mechanical integrity (increased wall thickness and strength) while maintaining its hydraulic diameter as large as possible. The improved DWPF glass pump (pump 2) was installed on September 15, 2004. The impact of the new design on pump life, along with analysis of the glass pumps impact on melt rate in the DWPF Melter is discussed in this paper.

Post Fire Transient Temperature Distribution in Drum Type Packages

This study investigates the temperature distribution in an idealized cylindrical package subjected to the HAC Fire transient. Cases for several common overpack materials, with thermal conductivity spanning two orders of magnitude, are considered. The results show that the interior temperature distribution and maximum interior temperature are determined by the heat generation of the contents and the thermal resistance of the package materials. Heat generation has a dominant effect on the peak temperature in the center (containment vessel region) of the package, when the internal thermal resistance is high. For cases where the internal resistance is low, heat conducted into the interior during the fire determines the peak temperature in the center, containment vessel region. The thermal wave effect, where the interior temperature continues to rise after the end of the fire exposure, is present in all cases. The study complements the parametric studies of effects of thermal properties on thermal response of packages which were previously reported.Copyright

Development of a Light Weight Modular Package for the Transport of Hazardous Evidence

The Hazardous Materials Response Unit (HMRU) of the Federal Bureau of Investigation (FBI) requires packages for transporting evidence consisting of or contaminated with hazardous materials. The packages must be lightweight, have a large internal capacity, provide leak-tight containment and be capable of containing chemical, biological or nuclear hazardous materials. This paper details the development of a new package with a thin wall aluminum containment vessel, a non-bolted ring-locking type closure and a modular overpack for impact and thermal protection.Copyright