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Los Alamos National Laboratory (LANL) generates radioactive waste as a result of various activities. Operational waste is generated from a wide variety of research and development activities including nuclear weapons development, energy production, and medical research; environmental restoration (ER), and decontamination and decommissioning (D&D) waste is generated as contaminated sites and facilities at LANL undergo cleanup or remediation. The majority of this waste is low-level radioactive waste (LLW) and is disposed of at the Technical Area 54 (TA-54), Area G disposal facility. U.S. Department of Energy (DOE) Order 435.1 (DOE, 2001) requires that radioactive waste be managed in a manner that protects public health and safety, and the environment. To comply with this order, DOE field sites must prepare site-specific radiological performance assessments for LLW disposal facilities that accept waste after September 26, 1988. Furthermore, sites are required to conduct composite analyses that account for the cumulative impacts of all waste that has been (or will be) disposed of at the facilities and other sources of radioactive material that may interact with the facilities. Revision 4 of the Area G performance assessment and composite analysis was issued in 2008 (LANL, 2008). These analyses estimate rates of radionuclide release from the waste disposed of at the facility, simulate the movement of radionuclides through the environment, and project potential radiation doses to humans for several on- and off-site exposure scenarios. The assessments are based on existing site and disposal facility data, and on assumptions about future rates and methods of waste disposal. The Area G disposal facility consists of Material Disposal Area (MDA) G and the Zone 4 expansion area. To date, disposal operations have been confined to MDA G and are scheduled to continue in that region until MDA G undergoes final closure at the end of 2013. Given its impending closure, efforts have been made to utilize the remaining disposal capacity within MDA G to the greatest extent possible. One approach for doing this has been to dispose of low-activity waste from cleanup operations at LANL in the headspace of selected disposal pits. Waste acceptance criteria (WAC) for the material placed in the headspace of pits 15, 37, and 38 have been developed (LANL, 2010) and the impacts of placing waste in the headspace of these units has been evaluated (LANL, 2012a). The efforts to maximize disposal efficiency have taken on renewed importance because of the disposal demands placed on MDA G by the large volumes of waste that are being generated at LANL by cleanup efforts. For example, large quantities of waste were recently generated by the retrieval of waste formerly disposed of at TA-21, MDA B. A portion of this material has been disposed of in the headspace of pit 38 in compliance with the WAC developed for that disposal strategy; a large amount of waste has also been sent to off-site facilities for disposal. Nevertheless, large quantities of MDA B waste remain that require disposal. An extension of pit 38 was proposed to provide the disposal capacity that will be needed to dispose of institutional waste and MDA B waste through 2013. A special analysis was prepared to evaluate the impacts of the pit extension (LANL, 2012b). The analysis concluded that the disposal unit could be extended with modest increases in the exposures projected for the Area G performance assessment and composite analysis, as long as limits were placed on the radionuclide concentrations in the waste that is placed in the headspace of the pit. Based, in part, on the results of the special analysis, the extension of pit 38 was approved and excavation of the additional disposal capacity was started in May 2012. The special analysis presented here uses performance modeling to identify a disposal plan for the placement of waste in pit 38. The modeling uses a refined design of the disposal unit and updated radionuclide inventories to identify a disposal configuration that promotes efficient utilization of the pit and ensures continued compliance with DOE Order 435.1 performance objectives. Section 2 describes the methods used to conduct the analysis; the results of the evaluation are provided in Section 3. The disposal plan for pit 38 is provided in Section 4 and the conclusions of the investigation are provided in Section 5. Throughout the report, pit 38 is used to refer to the entire disposal unit, including the existing pit and the extension that is currently under construction. Where a distinction between the two portions of the pit is necessary, the existing unit is referred to as pit 38 proper and the new portion of the pit as the pit 38 extension or, more simply, the extension.
The U.S. Army Corps of Engineers' (USACE) highest priority is the protection of human health and the environment and public and worker safety during the cleanup, transportation, and disposal of Formerly Utilized Sites Remedial Action Program (FUSRAP) material. In addition to following all appropriate federal and state rules and regulations, the USACE has its own safety program that ensures that we are being protective. One aspect of the USACE FUSRAP is the radioactive waste disposal strategies that we must consider. The USACE will only dispose of FUSRAP material in a facility that is licenses/permitted to accept it. The estimated exposures to facility workers and members of the public from the permitted disposal of FUSRAP wastes is evaluated as part of this process. The USACE uses the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) process to study and remediate FUSRAP sites. An evaluation is performed to decide whether it is best to manage the waste on-site or off-site and the requirements for disposal. The action selected must be protective of human health and the environment and must comply with regulations. When making the decision, there are several other factors taken into consideration including cost of the disposal and whether the public and state agencies support the action. Prior to determining disposal options, wastes must first be characterized. This involves an evaluation of both site history and analytical data. Determining the proper disposal requirements and subsequent disposal option involves: Characterizing the waste as stated above. This is important because there are several regulatory agencies which may oversee management of the waste. The US Nuclear Regulatory Commission, the US Environmental Protection Agency (US EPA), the US Department of Transportation, and state hazardous waste and/or radiation protection agencies may all have varying degrees of involvement. Identifying disposal requirements. Certain wastes must be disposed at licensed radioactive waste disposal facilities. Wastes containing US EPA regulated hazardous waste must be disposed at permitted hazardous waste disposal facilities. Certain wastes must be disposed at facilities licensed/permitted for both radioactive and hazardous waste. Some lower activity wastes may be accepted for disposal at other types of landfills. Considering acceptance criteria of the disposal facility. Radionuclides and/or hazardous constituents in the waste, as well as physical and chemical form of the waste, are evaluated to ensure they meet the acceptance criteria of the receiving facility's license and/or permit. If they don't, another disposal location must be used. Considering the accessibility and location of the disposal facility. Some facilities are able to accept shipments only by truck and others can accept material via railcar as well. The distance to a disposal facility impacts the risk of transportation accidents and efficient use of project resources such as the number of trucks required to perform the transportation. These factors are also important in evaluating whether material can be cost effectively shipped to a disposal facility. Evaluating the compliance status of the receiving facility. It is not assumed that just because a facility has a license or permit that it is acceptable for the USACE' waste. Prior to selecting a facility for disposal of FUSRAP waste, a site visit, audit and consultation with the US EPA is required to determine whether there are any known relevant violations at the facility. Facilities that have violations that negatively impact the USACE or US EPA approval of the facility are not used for disposal of FUSRAP waste. Once a facility is selected. The USACE procures contracts, or utilizes existing contracts, to facilitate the transportation and disposal action. Additionally, the USACE continues to consult with US EPA routinely to confirm the compliance status of the facility. Considering state acceptance of wastes to a facility. The USACE seeks to obtain written authorization from the facility state regulator indicating the action is compliant with existing licenses, permits, laws, and regulations. Each of these factors is considered by the USACE in selecting a FUSRAP disposal location. The goal is to provide safe, cost effective disposal which is protective of human health and the environment and which complies with all regulatory requirements. These steps all feed in to the disposal strategy consideration that USACE must go through for our FUSRAP waste streams. There are a number of challenges in the process to include In order to achieve the Congressional mandate of completing cleanup work under FUSRAP in a more cost effective, timely manner, while assuring protection of public health and safety. USACE must determine all disposal options that are available for the types of waste at each FUSRAP site. As a solution, completion of a disposal strategy document can help ensure this goal is met and will foster consistency across the FUSRAP. (authors)
Direct disposal of commercial spent nuclear fuel (SNF) in dual-purpose canisters (DPCs) could avoid the cost and complexity of re-packaging spent fuel into smaller purpose-built containers, avoid disposing of the DPC hulls as low-level waste, and potentially decrease worker dose. Technical objectives for disposal are: 1) safety of workers and the public, 2) engineering feasibility; 3) thermal management; and 4) criticality control after permanent closure of a repository. The postclosure safety case for DPC direct disposal would resemble that for any repository-waste isolation would be enhanced by choosing host geology in which radionuclide transport is diffusion dominated, and for which transport properties and pathways are insensitive to the expected temperature history. Containment functions would be assigned to the disposal overpack, and published data show that suitable materials exist for most possible disposal environments. Earlier studies showed that DPC-based waste packages would be only slightly larger and heavier than those proposed for a repository in volcanic tuff. Engineered solutions are available for transporting and emplacing them underground, although some could be the largest of their kind. The cost of DPC direct disposal in various geologic settings has been compared to options involving a change to loading standardized multi-purpose canisters, or continuing to load DPCs and re-packaging all of them for disposal. In general DPC direct disposal would cost tens of billions of dollars less, in packaging and disposal costs. Calculations for emplacement in hard rock and sedimentary rock show that host rock peak temperature targets of 100 to 200 deg.C could be met by managing fuel age and burnup, with repository closure at up to 150 years from reactor discharge. For disposal in salt, DPC-based waste packages could be emplaced at only 50 to 100 years from discharge, depending on burnup. Sedimentary media such as shales pose special challenges especially if they have low thermal conductivity. If backfill is used around DPC-based packages its peak temperature could be 150 to 200 deg.C. Without flooding of waste packages with ground water, criticality can never occur. However, some small number of disposal overpacks could fail within the postclosure performance period due to corrosion or disruptive events. Once flooded, the aluminum-based neutron absorber materials used in most DPCs would readily degrade. Analysis has shown that even without neutron absorbers, virtually all DPCs could be subcritical if flooded with chloride brines such as would occur in a salt repository. The licensing basis for existing DPCs involves criticality analysis that may be conservative compared to fuel that is actually loaded, and the difference provides uncredited reactivity margin. Uncredited margin can offset increases in reactivity associated with flooding and basket degradation. For flooding with fresh water, with loss of neutron absorbers, many DPCs have been shown to be subcritical using uncredited margin. Significantly fewer are subcritical if the fuel basket also degrades. Thus, the materials of DPC basket construction (e.g., aluminum or carbon steel) could be deleterious if they fully corrode, along with the neutron absorbers, during the performance period. Logistical simulations are used to better understand the relationship between the needed DPC decay storage time for disposal, and the timing of future events such as the repository opening date, or a transition to loading multi-purpose (disposable) canisters at nuclear power plants. Results show that the maximum benefit from implementing a new canister design, with respect to shortening the cooling time for all SNF including that in DPCs, is associated with the earliest repository start date. As time passes more of the total SNF inventory will be in DPCs such that the value of a transition to multi-purpose canisters will decline, and the remaining options are DPC direct disposal and re-packaging in purpose-designed disposal canisters. Fuel age at emplacement is of interest to evaluate potential impacts from future changes in the fuel management system that could place fuel age limits on dry storage or transportation. The minimum fuel age at emplacement (best-case) is obtained by re-packaging all DPCs into smaller canisters for disposal, thus drastically decreasing the needed decay storage time for any geologic disposal setting. If the industry transitions to smaller, multi-purpose canisters, and without re-packaging, the fuel age at emplacement would be comparable to the best case if: 1) the emplacement power limit is high enough, or 2) both the transition and the repository start date occur early (e.g., 2036 was analyzed). Technical feasibility evaluation continues to show that direct disposal could be safe and cost effective, for some DPCs and in some geologic settings. Direct disposal of a substantial fraction of existing DPCs, limited mainly by thermal management, uncredited criticality margin, materials of DPC basket construction, and the salinity of ground water in the disposal environment, could be part of the overall waste management system. (authors)
As part of ongoing cleanup activities at the Idaho National Laboratory (INL), closure of the Radioactive Waste Management Complex (RWMC) is proceeding under the Comprehensive Environmental Response, Compensation, and Liability Act (42 USC 9601 et seq. 1980). INL-generated radioactive waste has been disposed of at RWMC since 1952. The Subsurface Disposal Area (SDA) at RWMC accepted the bulk of INL’s contact and remote-handled low-level waste (LLW) for disposal. Disposal of contact-handled LLW and remote-handled LLW ion-exchange resins from the Advanced Test Reactor in the open pit of the SDA ceased September 30, 2008. Disposal of remote-handled LLW in concrete disposal vaults at RWMC will continue until the facility is full or until it must be closed in preparation for final remediation of the SDA (approximately at the end of fiscal year FY 2017). The continuing nuclear mission of INL, associated ongoing and planned operations, and Naval spent fuel activities at the Naval Reactors Facility (NRF) require continued capability to appropriately dispose of contact and remote handled LLW. A programmatic analysis of disposal alternatives for contact and remote-handled LLW generated at INL was conducted by the INL contractor in Fiscal Year 2006; subsequent evaluations were completed in Fiscal Year 2007. The result of these analyses was a recommendation to the Department of Energy (DOE) that all contact-handled LLW generated after September 30, 2008, be disposed offsite, and that DOE proceed with a capital project to establish replacement remote-handled LLW disposal capability. An analysis of the alternatives for providing replacement remote-handled LLW disposal capability has been performed to support Critical Decision-1. The highest ranked alternative to provide this required capability has been determined to be the development of a new onsite remote-handled LLW disposal facility to replace the existing remote-handled LLW disposal vaults at the SDA. Several offsite DOE and commercial disposal options exist for contact-handled LLW; however, offsite disposal options are either not currently available (i.e., commercial disposal facilities), practical, or cost-effective for all remote-handled LLW streams generated at INL. Offsite disposal of all INL and tenant-generated remote-handled waste is further complicated by issues associated with transporting highly radioactive waste in commerce; and infrastructure and processing changes at the generating facilities, specifically NRF, that would be required to support offsite disposal. The INL Remote-Handled LLW Disposal Project will develop a new remote handled LLW disposal facility to meet mission-critical, remote-handled LLW disposal needs. A formal DOE decision to proceed with the project has been made in accordance with the requirements of National Environmental Policy Act (42 USC§ 4321 et seq.). Remote-handled LLW is generated from nuclear programs conducted at INL, including spent nuclear fuel handling and operations at NRF and operations at the Advanced Test Reactor. Remote-handled LLW also will be generated by new INL programs and from segregation and treatment (as necessary) of remote handled scrap and waste currently stored in the Radioactive Scrap and Waste Facility at the Materials and Fuels Complex.
In this paper, the experiences and directions of the construction of the LILW disposal facility in Korea are discussed. The LILW disposal facility is being constructed in Gyeongju-si, Korea. The disposal facility is officially called 'Wolsong Low and Intermediate Level Radioactive Waste Disposal Center (WLDC)'. It can dispose of 800,000 drums (hereafter, 'drums' means '200 liter drum equivalents' unless specified otherwise) of radioactive waste in a site of 2,060,000 m{sup 2}. The first stage of the LILW facility construction was completed in June 2014, and approved for use by Nuclear Safety and Security Commission (NSSC) in December 2014. The first stage of the LILW facility is a type of underground silo with disposal capacity of 35,200 m{sup 3} (100,000 drums). The first stage of the LILW facility consists of a construction tunnel, an operation tunnel, an access shaft and six silos, etc. Silo for final disposal is located 80∼130 m below sea level, 25 m in diameter and 50 m in height. The capacity of each silo is approximately 16,700 drums. The second stage of the LILW facility is under construction to be completed by December 2019. Site construction is currently underway. The second stage of the LILW facility is a type of near-surface disposal with disposal capacity of 32,875 m{sup 3} (125,000 drums). This stage of the LILW disposal facility consists of an underground gallery, three movable cranes and twenty vaults, etc. Vault for final disposal is located 70 m above sea level, 20 m in width, 20 m length and 10 m in height. The capacity of each vault is approximately 6,250 drums. These stages of the LILW disposal facilities are together called LILW complex disposal facility. It's the world's first LILW disposal facility with two different types of disposal facilities in one site. For efficient operation, these disposal facilities share a reception and storage building, waste water treatment system, measurement and monitoring system, etc. After construction of the first two stages is completed, LILW disposal facilities will be incrementally expanded, and as the whole LILW disposal facilities are completed, all LILW in Korea will be managed safely in WLDC. (authors)
This paper provides the status and experiences of Low and Intermediate-level radioactive Waste (LILW) disposal facility in Korea. The LILW disposal facility is being constructed in Gyeongju-si, Korea. It can dispose of 800,000 drums (hereafter, 'drums' means '200 liter drum equivalents' unless specified otherwise) of radioactive waste in a site of 2,060,000 m{sup 2}. The first stage of the LILW facility construction was completed in June 2014, and approved for use by Nuclear Safety and Security Commission (NSSC) in December 2014. The first stage of the LILW facility, which is a type of underground silo with disposal capacity of 35,200 m{sup 3} (100,000 drums), consists of a construction tunnel, an operation tunnel, an access shaft, and six silos, etc. Silo for final disposal is located 80∼130 m below sea level, 25 m in diameter and 50 m in height. The capacity of each silo is approximately 16,700 drums. The second stage of the LILW facility is under construction and will be completed by December 2020. The second stage of the LILW facility, which is a type of near-surface disposal with disposal capacity of 32,875 m{sup 3} (125,000 drums), consists of an underground gallery, three movable cranes and twenty vaults, etc. Vault for final disposal is located about 100 m above sea level, 20 m in width, 20 m length and 10.9 m in height. The capacity of each vault is approximately 6,250 drums. A second receipt and storage facility is to be completed by June 2021. This facility is under designing to prepare for further increasing radioactive waste receipt quantities. It has storage capacity of 10,000 drums (existing receipt and storage facility have storage capacity of 7,000 drums)and will be divided into several sections for pre-disposal work, storage, a passage to link the existing facility to the second receipt and storage facility and truck bay, etc. These components of the LILW disposal facilities are together called LILW complex disposal facility. It is the world's first LILW disposal facility with two different types of disposal facilities in one site. For efficient operation, these disposal facilities share a receipt and storage building, a waste water treatment system, a measurement and monitoring system, etc. Once the construction of the first two stages is completed, LILW disposal facilities will be incrementally expanded, and as the whole LILW disposal facilities are completed, all LILW in Korea will be disposed of these disposal facilities efficiently according to its radioactivity level and managed safely by KORAD. (authors)