Technology Development to Support OCRWM Transportation Activities

Technology development activities are being conducted by the Department of Energy, Office of Civilian Radioactive Waste Management to support spent nuclear fuel and high-level radioactive waste transport to the federal repository at Yucca Mountain, Nevada in 2010. The paper discusses the motivation for pursuing transport technologies for a private sector operated transportation program, and describes some of the current technologies being pursued.

The State of Stress of Transportation Packages During Hypothetical Accident Free-Drop Impact

In general, only stress-based design criteria are used and accepted by regulatory agencies to demonstrate transportation package structural performance by analysis. However, as stated in the regulatory guidance, other criteria may be accepted on a case-by-case basis. There are efforts to develop alternate design criteria, based on strain or strain energy density, to demonstrate acceptable structural performance of packages under the HAC free drop. Prior to developing such design criteria, two elements must be understood and developed: (1) the failure mechanism from strain or strain energy density and (2) a theory of failure. However, in order to understand the failure mechanism and to develop a theory of failure, the stress state behavior (stress fields) must be known. As a first step, this paper examines and reports the stress states for free-drop impact loadings on two transportation packages currently in use.

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.

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.

Pressure Indication of 3013 Inner Containers Using Digital Radiography

Plutonium bearing materials packaged for long term storage per the Department of Energy Standard 3013 (DOE-STD-3013) are required to be examined periodically in a non-destructive manner (i.e. without compromising the storage containers) for pressure buildup. Radiography is the preferred technology for performing the examinations. The concept is to measure and record the container lid position. As a can pressurizes the lid will deflect outward and thus provide an indication of the internal pressure. A radiograph generated within 30 days of creation of each storage container serves as the baseline from which future surveillance examinations will be compared. A problem with measuring the lid position was discovered during testing of a digital radiography system. The solution was to provide a distinct feature upon the lower surface of the container lid from which the digital radiography system could easily track the lid position.

Revision of NNSA Packaging Certification Division’s Safety Guide 100 (SG-100)

The Transportation Technologies Group (TTG) of Oak Ridge National Laboratory (ORNL) is currently tasked, by National Nuclear Security Administration (NNSA) Service Center (SC), Office of technical Support (OTS), National Security Department (NSD), Packaging Certification Division (PCD), to revise the Defense Programs’ Safety Guide 100 (SG-100). SG-100, formally entitled “Design Guide for Packaging and Offsite Transportation of Nuclear Components, Special Assemblies, and Radioactive Materials Associated with the Nuclear Explosives and Weapons Safety Program” is being revised to reflect current regulations as well as to incorporate lessons learned over the past several years. SG-100 was last published in 1994 as Revision 1, and has served as the key guidance document for the development of Defense Programs’ Type B package designs as well as their testing and testing and certification. Since that time, there have been two major revisions to the U.S. packaging and transportation regulations (due to revisions to US federal regulations, IAEA guidelines, and national standards), re-engineering of the DOE establishing the semi-autonomous NNSA, as well as numerous improvements in the analytical tools and methodologies used in package design and confirmatory review. This revision to SG-100 will capture these changes as well as reflect various lessons learned from certification reviews which have taken place over the past decade. TTG has also been tasked by PCD to present a workshop based on the revised SG-100 in September 2004.

Computer Simulation of a Transportation Package Impacting Concrete and Soil Targets

This paper compares transportation mockup cask impact test results onto real surfaces with FEA numerical simulation results. The impact test results are from a series of cask impact tests that were conducted by Sandia National Laboratories (Gonzales 1987). The Sandia tests were conducted with a half-scale instrumented cask mockup impacting an essentially unyielding surface, in-situ soil, concrete runways, and concrete highways. The cask numerical simulations with these same surfaces are conducted with ABAQUS/Explicit, Version 5.8, The results are then compared and evaluated to access the viability of using numerical simulation to predict the impact behavior of transportation casks under hypothetical accident conditions.

Onsite Packaging and Transport of Tritium Waste

Radioactive material packagings designed for out-of-commerce shipments are not necessarily subject to the same regulatory requirements as packagings designed for in-commerce service. For example, DOE Order 460.1B permits application of the notion of Equivalent Safety to out-of-commerce shipping within DOE sites. Equivalent safety can be viewed as a reduction in 10 CFR 71 design conditions without a corresponding loss of public health and safety. This paper presents a packaging design identified as the Tritium Spent Melt Overpack (SMO) that successfully utilized equivalent safety at the Savannah River Site (SRS). Because the spent melt materials are highly radioactive, the container must be loaded and closed remotely. The SMO design is a based on twenty-foot long eighteen-inch diameter pipe, with one end closed by welded plate and the open end closed by a latching plug that incorporates bore seals. The SMO receives a single sixteen-inch diameter by 16-foot long crucible partly filled with the waste product from the tritium extraction process. The loaded overpack is moved from the SRS Tritium Extraction Facility inside a heavily shielded cask. Upon arrival at a waste silo designed to receive the overpack, it is removed from the shielding cask by remote means and placed in the long-term storage silo. This paper provides an overview of the SMO overpack design and its operation.

Radiolytic Hydrogen G Values for Waste Materials

The radiolytic generation of hydrogen and other gases that support combustion are of particular concern for the transportation and handling of packages containing radioactive wastes and materials. An estimate of initial concentration of hydrogen and the rate of hydrogen generation through radiolysis within packages is therefore needed before shipping or storing radioactive materials. The most common method to estimate hydrogen gas generation is called the G value method. This paper documents a comprehensive database of hydrogen gas G values. The database is available electronically. It includes over 400 G values compiled from over 50 papers available in the open literature. The database includes: paper citation, author(s), author(s) affiliation, paper comments, material type, material sub-type, material comments, G value by decay mode, and G value comments.

Development of a Transportation Package With a Non-Circular Cross Section Containment Vessel for the Transport of Hazardous Evidence

The Hazardous Materials Response Unit (HMRU) of the Federal Bureau of Investigation (FBI) needs packages for transporting evidence consisting of or contaminated with hazardous materials. These packages must be lightweight, have a large capacity, provide leak-tight containment and be capable of transporting a large variety of hazardous materials. To maximize space efficiency and handling ease, the HMRU requested that a modular package with a containment vessel of non-circular cross-section be developed for their use. This paper details the preliminary development of this package.