National Transuranic Waste Management Program
The National Transuranic Waste Management Program, also called the National TRU Program, addresses waste acceptance criteria and requirements for packaging and shipping waste to the WIPP repository. One of the committee's tasks is to identify areas for improvement in the National TRU Program that may increase safety to workers and the public, system throughput, efficiency, or cost-effectiveness. The National TRU Program was reviewed in detail in the committee's interim report (Appendix A1). This chapter gives a status report on the issues discussed in the interim report and reviews other issues that have emerged during the committee's deliberations. The issues addressed in this chapter relate to two areas: (1) waste characterization and packaging and (2) waste transportation.
WASTE CHARACTERIZATION AND PACKAGING
The committee has identified opportunities for improvement in the TRU waste management system concerning waste characterization and packaging requirements and the total inventory of organic material in the repository.
Waste Characterization and Packaging Requirements
The issues of waste characterization and packaging requirements have been discussed in detail in the interim report (Appendix A1). The principal finding was that many requirements and specifications concerning waste characterization and packaging lacked a safety or legal basis. In addition, many of these same requirements resulted in health and safety risks and added costs. The added safety risks derive from radiation exposure of workers due to the extra handling of waste imposed by some of the requirements. For instance, visual examination of a fraction of waste stream containers to confirm radiography results and information from the history of the container (acceptable knowledge) is a procedure not required by the EPA that increases radiation exposure of workers. The committee recommended in its interim report that the DOE eliminate self-imposed waste characterization requirements that lack a safety or legal basis.
The committee is encouraged by progress made since the interim report to eliminate unnecessary
procedures. In particular, the DOE has initiated a program to review all waste characterization and packaging requirements and to reduce or eliminate those that do not contribute to improved safety or that are not required by law. The DOE may obtained a tenfold reduction of the number of containers to be opened for visual examination by requesting a modification of the WIPP's Hazardous Waste Facility Permit (Appendix A2).
Recommendation: The committee recommends that the DOE's efforts to review waste characterization and packaging requirements continue and that changes be implemented over the entire National TRU Program. The committee recommends that the resources required to complete these improvements be made available by the DOE.
Total Inventory of Organic Material in the Repository
A new issue concerning waste characterization has emerged since the committee visited the WIPP site in May 2000. This issue addresses the regulatory limits on the total inventory of organic material allowed in the repository. The performance assessment indicates that there could be significant carbon dioxide generation in the repository due to the decomposition of organic material. Although the committee does not consider gas generation an important safety issue (see Chapter 2), it is concerned whether the current monitoring program will provide the information required to assess compliance with total repository limits of organic material. Title 40 CFR 194.24 states that “the Department [of Energy] shall specify the limiting value ... of the total inventory of such waste proposed for disposal” (EPA, 1996). The DOE has therefore established the limit for organic material in the repository to be 20 million kilograms (DOE, 1996; Table 4-0) on the basis of the average waste composition.
However, the DOE's definition of “waste” includes only what is inside the waste container and does not include either the container itself or any of the auxiliary material buried with the waste. Examples of such auxiliary material are plastic films used to stabilize drums for shipping and handling, plastic bags and corrugated cardboard used as magnesium oxide containers, wooden waste boxes, plastic liners of waste drums, and pressed wood “slip sheets” used between layers of drums and waste boxes. Figure 3.1 shows a picture of waste and auxiliary material in one of the rooms of the repository. Thus, there is a considerable inventory of materials, mostly cellulosics, that are not considered TRU waste but are foreign to the natural setting of the Salado Formation. The principal concern of the committee is that the auxiliary material does not appear to be accurately inventoried. Therefore, it is impossible to know whether the total organic material limit is exceeded.
Recommendation: The committee recommends a risk-based analysis of the total organic material regulatory limits in the WIPP. If accounting for the organic material is important to the safety of the repository, an inventory record system should be implemented as soon as possible to provide a basis for meaningful safety analysis.
The committee has examined various aspects of the WIPP TRU waste transportation system, focusing on system safety and on cost-effectiveness of planned and ongoing activities. In its interim report (Appendix A1), the committee reviewed the DOE's TRANSportation tracking and COMmunication (TRANSCOM) system and its emergency response program. Two other issues have been revisited in this report: the potential use of rail as a shipping option for a fraction of TRU waste and the gas genera-
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tion safety analysis for the Transuranic Package Transporter, Model II (TRUPACT-II) containers. Figure 3.2 shows the internal structure of a TRUPACT-II container. Figure 3.3 shows a truck transporting three TRUPACT-II containers.
DOE's Communication and Notification Program
In its interim report (Appendix A1), the committee recommended that the DOE improve the reliability and ease of use of the TRANSCOM system. On November 21, 2000, a truck hauling waste to WIPP strayed from its designated route as the driver missed the exit from Interstate 25 onto Route 285 toward Carlsbad. The driver proceeded 27 miles before the New Mexico State Police, equipped with a TRANSCOM system, realized the error and turned the truck around. It appears that the TRANSCOM headquarters situated in Oak Ridge, Tennessee, did not notify the driver until a state policeman noticed the error (DOE, 2001). This “strayed truck” episode is an example of the poor reliability of the system, not from a technical point of view since the TRANSCOM was apparently functioning correctly, but from the perspective of the human factor.
The DOE appears to be systematic and expeditious in its development and use of a new, efficient, comprehensive, and state-of-the-art communication and notification system, known as TRANSCOM 2000. The new system will use off-the-shelf, advanced information and communication technologies to track shipments from start to end. Full-scale implementation of TRANSCOM 2000 is scheduled for June 2001. After discussion with transportation management staff and in reaction to the DOE's response to its
interim report (Appendix A2), the committee finds that overall, the DOE has taken active steps to address concerns about the reliability and ease of use of the TRANSCOM system. Moreover, the DOE has integrated new features into TRANSCOM 2000, such as alarms, more frequent satellite and computer tracking, and stronger training for truck drivers to avoid future “strayed truck” episodes. Other suggestions to improve the safety and reliability of TRANSCOM could be the use of checklists, key schedule reporting, and “call-ins” at important route changes.
There may also be further opportunities to improve the performance of the TRANSCOM 2000 system. For instance, integrating TRANSCOM 2000 with other corridor states' information technology programs such as intelligent transportation systems (ITS). More generally, TRANSCOM 2000 must meet performance-monitoring standards similar to those of other advanced systems, such as the air traffic control system, particularly as shipments become routine and drivers and supervisors may become complacent. Investment in tracking and communication systems for the WIPP will also be useful for future radioactive waste transportation systems.
Recommendation: The committee recommends that the DOE implement as soon as possible the new TRANSCOM 2000 communication and notification system. Moreover, because human factors are an important element of transportation system quality, TRANSCOM 2000 should include methods to minimize the occurrence and impact of human errors.
DOE's Emergency Response Program
Concerning the emergency response program for the WIPP, the committee recommended, in its interim report (Appendix A1), that the DOE explore with corridor states and other interested parties how to develop processes and tools for maintaining up-to-date spatial information on the location, capabilities, and contact information for the following:
regional response teams, and
other resources that might be needed to support effective emergency response in the event of a transportation incident involving a WIPP shipment.
This recommendation was made in recognition of the fact that, presently, there is no quality control program in existence to evaluate periodically and systematically the extent of training, emergency capabilities, and deficiencies within the states and along WIPP transportation corridors. The committee fully understands and recognizes that the primary responsibility for management and response to hazardous material incidents in transportation rests with state and local authorities and jurisdictions. Although WIPP corridor states actively coordinate in varying degrees with the DOE to ensure the safety of WIPP shipments, the general public may often view this responsibility as ultimately resting with the DOE as the system manager. The public might well expect qualified and trained emergency response coverage along an entire route. In the committee's view, the DOE could face heavy criticism if an event demonstrates weaknesses in the emergency response program, regardless of whether the safety consequences are serious. Any system-level integration necessary to ensure adequate emergency response would have to recognize and coordinate among the jurisdictional boundaries of the various responsible state and local agencies.
To date, the committee is concerned about the progress being made in the emergency response area. For example, only 7 of the 20 states situated along the transportation corridor participated in the last DOE emergency response training class in Carlsbad, New Mexico (DOE, 2000e). The committee acknowledges the challenges faced by the respective states in providing resources to ensure adequate coverage. There continues to be a need for the DOE to facilitate the involvement of states and other interested parties to determine where emergency response capabilities are lacking along transportation routes and to support the states in correcting deficiencies. The committee is encouraged by the new DOE training program, through which DOE trainers have traveled to Indiana, Colorado, Louisiana, and Nevada to teach emergency response professionals what to do in case of an accident involving a WIPP shipment (Westinghouse News, 2001a,b,c,d). A further example for DOE to improve the corridor states' involvement in the emergency response program is to organize training courses through distant learning.
Recommendation: The committee recommends that the DOE facilitate the involvement of states in developing and maintaining an up-to-date, practical, and cost-effective spatial information database system to coordinate emergency responses. The DOE should also develop an ongoing assessment program for states' emergency response capabilities and allocate training resources to address deficiencies in coverage along WIPP routes.
Rail as a Transportation Option for Certain TRU Waste
In its interim report (Appendix A1), the committee recommended that DOE reduce the number of truckloads required to transport waste to WIPP, thereby reducing the associated transportation risks.1 The committee suggested that a way to reduce the number of shipments is to reevaluate the technical and regulatory feasibility of shipping high-wattage TRU waste using a railcar shipping system. The WIPP has access already to rail via a rail spur siding, which runs into the facility.
In response to this recommendation, the DOE (2000c) recently issued a report CH-TRU Waste Transportation System Rail Study. This study examined the feasibility of shipping CH-TRU waste from four DOE facilities to WIPP by commercial rail and compared the relative costs of using rail rather than the present use of the highway. The study also examined the feasibility and cost-effectiveness of using several alternative packaging to TRUPACT-II. TRUPACT-II containers, because of their size, shape, or regulatory limits, are not always efficiently utilized during transportation; therefore, an increased number of shipments or repackaging of the waste is sometimes required. The DOE concluded that rail shipment of TRU waste to WIPP might be competitive if certain conditions are satisfied. Those conditions involve negotiation of a more favorable rail rate and development of an alternate type B overpack to TRUPACT-II that would accommodate more packages, thus reducing the number of shipments required.
A recent article (Neill and Neill, 2000) asserts that rail offers considerable advantages, at least with respect to shipments from the Hanford and the Idaho National Engineering and Environmental Laboratory sites. The authors make specific recommendations concerning the use of rail that might enable the DOE to ship TRU waste more efficiently while reducing transportation risk. The committee suggests
1On November 2, 2000, a new type of container, called HalfPACT, designed to supplement TRUPACT-II for road transportation, was certified by the U.S. Nuclear Regulatory Commission. The new container is approximately 30 inches shorter than TRUPACT-II and can be utilized more efficiently to transport TRU waste. The DOE estimated that the new HalfPACT container will eliminate about 2,000 projected shipments to the WIPP site.
Sidebar 3.1 The ATMX Railcar System as an Alternative Transportation System?
“ATMX” is an acronym to denote the railcars used by the DOE to ship nuclear weapons components and TRU waste. “AT” stands for Atchison Topeka, the rail carrier. “M” signifies munitions, and “X” on a railcar signifies private ownership (in this case, by the U.S. government), rather than ownership by the railroad company. This system was used by the DOE (and formerly the U.S. Atomic Energy Commission) from about 1968 to 1989 to safely transport more than 1,100 shipments of CH-TRU waste from the Mound Laboratory and Rocky Flats to the Idaho National Engineering Laboratory. The ATMX (600 series) is a specially designed steel railcar with a bolted-on steel cover and an interior compartmentalized by steel frames. Closed steel boxes or bins are positioned and stored in each compartment, and internal packagings are placed in the boxes or bins. Internal packagings need only meet U.S. Department of Transportation (DOT) Type A package test standards and are relieved from Type B (accident-resistant) package test parameters. Each ATMX railcar can accommodate a maximum of 20 crates or 140 55-gallon steel drums. In June 1999, the DOT issued the tenth revision of DOT-E 5948, authorizing the shipment of TRU waste by rail from Miamisburg, Ohio (the Mound Laboratory), to a yet-to-be-designated DOE facility where it will be processed for eventual shipment to the WIPP in TRUPACT-II containers. This option appears to be a very reasonable and cost-effective method of transferring the relatively small amount of TRU waste at Mound to another DOE facility for processing as an alternative to setting up a facility at Mound itself. Since the ATMX system is not certified by the USNRC, its use for rail shipments directly to the WIPP is precluded by the provisions of the Land Withdrawal Act and the Agreement with the State of New Mexico, which require that shipments to the WIPP be in USNRC-certified packages. To obtain USNRC “approval,” the DOE would have to support an application to the USNRC for exemption from certain test requirements for the Type B package mentioned in Title 10 CFR Part 71. For certain materials that eventually will not be transportable in TRUPACT-II containers due to high thermal loading, this would appear to be a desirable option for future consideration and possible pursuit by the DOE.
that the DOE develop a strategy to negotiate and reduce the overall rail freight costs and to identify the infrastructure (e.g., costs, emergency preparedness, and schedules) necessary for rail shipments.
In its interim report, the committee recommended the ATMX railcar system as an alternative transportation system for certain materials (see Sidebar 3.1). Specifically, the committee recommended that a risk-informed study should be prepared by the DOE to support an application to the United States Nuclear Regulatory Commission (USNRC) authorizing the use of the ATMX railcar system for shipments of inner waste packages that are unsuitable for placement in TRUPACT-II containers.
Recommendation: The committee recommends that all reasonable transportation options including reduction in the number of shipments, such as rail and road transportation with better-adapted containers, should be part of the decision-making process of transporting TRU waste from generator and storage sites to the WIPP. Future transportation studies should consider railway shipments and their impact on both the safety and the cost of the program. The DOE should also
continue to pursue the development of packaging alternatives for materials not suitable for TRUPACT-II containers.
Gas Generation Safety Analysis for TRUPACT-II Containers
The issue of hazardous gas generation in TRUPACT-II shipping containers stems from a U.S. Nuclear Regulatory Commission requirement (USNRC, 1999). The requirement states that, for the shipping container, “hydrogen and other flammable gases comprise less than 5% by volume of the total gas inventory within any confinement volume.” The problem is whether a flammable mixture could be generated and trigger an ignition, exothermic reaction, or explosive event with sufficient energy to breach the containment. Excessively restrictive gas generation requirements have severe consequences. The waste is repackaged to redistribute waste in containers to meet the wattage limits derived from gas generation requirements. This repackaging of waste exposes workers to radiation and increases the number of containers, thereby diluting the waste into a greater volume. Transportation-related risks (and costs) are also incurred in repackaging because the extra containers require additional shipping loads and additional truck trips, thereby increasing the likelihood of accidents.
For instance, plutonium-238 found in CH waste is considered a “high-wattage waste” because of its high specific activity (17.3 curies per gram). The USNRC significantly restricts the amount of plutonium-238 that can be transported by TRUPACT-II because of gas generation concerns. The DOE estimates that the repackaging of plutonium-238 in CH waste may involve more than a tenfold increase in the number of shipments of plutonium-238, to as many as 150,000 extra drums (Lechel and Leigh, 1998). The USNRC uses a decay heat limit in watts, originally established by the DOE, based on limiting the volume of hydrogen to less than 50 milliliters per liter of volume in the “innermost confinement barrier.” According to waste acceptance criteria for the WIPP, the wattage limit for TRUPACT-II containers is 40 watts (DOE, 1999).
Thus, there is also the matter of what constitutes the innermost confinement barrier in TRUPACT-II, since the containers may consist of separate individual plastic bags of waste (see Figure 3.2). One interpretation is that the requirement applies to these “inner packages.” Obviously, there are situations in which such an interpretation would make the flammable gas volume limitation a severe constraint on TRU waste shipments, given the plastic bag packaging practice and the number of different sizes that may occur in a single TRUPACT-II container. Finally, it is the understanding of the committee that the 5 percent volume limitation on hydrogen is intended to preclude the need for a specific safety analysis, which suggests that this limitation is a major source of conservatism and may not be cost-effective or risk-informed.
The committee was unable to verify the technical basis for the several sub-issues that are involved, including a realistic assessment of the conditions that could result in an explosive event in TRUPACT-II containers and a clear definition of what constitutes the innermost barrier. As already recommended in its interim report, the committee reiterates that a risk-informed analysis of WIPP-specific shipments would contribute to a better understanding of the real safety issues and, perhaps, provide a basis for alternative cost-effective criteria while reducing the risk.
In its response to the interim report (Appendix A2), the DOE agreed with the committee's recommendation that a safety analysis be performed to determine the quantity of hydrogen that, upon ignition, could damage the TRUPACT-II shipping container and possibly rupture the seals of the package. The committee is aware of and supports the DOE's initiative of obtaining more realistic G-values2 for hydro-
2The G-value is the measure of radiolytic yield. It is expressed by the number of molecules, in this case of H2, produced by 100 electronvolts of the ionizing radiation's energy absorbed by the medium, in this case the TRU waste.
gen generation and of exploring the use of hydrogen getters and inerted inner containers as a means of increasing wattage limits for transportation. Moreover, the DOE has applied for a revision of the USNRC's certificate of compliance to authorize the use of lower G-values for hydrogen generation based on matrix depletion, options for mixing of shipping categories, and use more realistic G-values for non-gas generating materials that are present. The committee supports this request.
Recommendation: The committee recommends a risk-informed analysis of WIPP specific shipment issues to identify core problems related to hydrogen generation and, perhaps, provide a basis for alternative cost-effective criteria while reducing the risk. The committee recommends the use of such risk-informed analysis in the application for revision of the USNRC certificate of compliance concerning hydrogen generation limits for transportation purposes.