Characterization and modeling studies of sites of underground testing on the NNSS were conducted after acceptance of the FFACO agreement in the mid-1990s. However, progress was slow and multiple problems were encountered with implementing the original UGTA strategy (Marutzky et al. , 2010). The strategy assumed sequential progress through planned characterization and modeling studies and underestimated modeling uncer­tainty and the importance of unanticipated scientific discoveries in characterization and modeling work. Progress, particularly progress in modeling studies, is often non-systematic with unexpected discoveries where these discoveries require rethinking of modeling approaches. Further, much of the initial modeling work for UGTA was focused on the physical and chemical processes of flow and transport rather than gaining information required to make regulatory decisions (process-driven modeling studies instead of decision-driven modeling studies). These difficulties culminated with a negative review by an external peer review panel in 1999 (IT Corporation, 1999) of the Frenchman Flat CAU data analysis and modeling studies. The panel found the studies insufficient to conclude the corrective action investigation stage of the UGTA strategy for the CAU.

The FFACO UGTA strategy was revised in 2009 (FFACO, 1996; as amended March 2010) working with NDEP to better represent the iterative nature of modeling studies, to more fully evaluate the impact of uncertainty on modeling results and to bring risk perspectives to the strategy. The origi­nal UGTA strategy was based on a standardized approach to modeling, monitoring and closure in place at all CAUs regardless of the hydrological source term and/or the proximity of testing areas to the boundaries of the NNSS. Additionally, the original strategy identified a single key regulatory decision near the end of the site characterization and model development stage (stage two of the corrective actions). If this decision was approved for an individual CAU, the studies would proceed to a 5-year proof of modeling results, followed by closure in place with implementation of a long-term monitoring network. All modeling studies would have been concluded at the end of the second corrective action stage.

Two significant changes were made in the revised strategy. First, the strategy was redesigned to be consistent with recent guidance by the National Academy of Sciences (NRC, 2007a) and the EPA (USEPA, 2009) on the use of modeling in regulatory decisions for environmental modeling. The UGTA strategy was redefined (FFACO, 1996; as amended March 2010) where the emphasis and culmination of the second stage was based on adequacy of model development. The third stage was redefined as a model evaluation stage, where model results are tested to build confi­dence that the model results can be used for the intended regulatory deci­sion. The fourth stage of the strategy was largely unchanged, an emphasis on CAU closure in place and implementation of a long-term monitoring network.

14.4.1 Asse II

At the same time that Germany was constructing its first NPPs, the govern­ment recognized that methods and technologies would need to be devel­oped for the final geological disposal of related heat-generating wastes. The permanent disposal of these wastes in salt domes was seen as providing a promising option for the development of a HLW repository. To further investigate the ability of a salt-rock formation to serve as a potential reposi­tory host rock, the German Federal Ministry of Education and Research (Bundesministerium fur Bildung und Forschung, BMBF) acquired the former Asse potash and rock salt mine in 1965 as a prototype facility for LLW and ILW disposal with strong emphasis on research and disposal technologies (BfS, 2011e). The facility was managed at the time by the GSF (Gesellschaft fur Strahlen — und Umweltforschung mbH), a major research centre in Germany, which later became the Helmholtz Zentrum Munchen (HZM). Management and operations of the Asse facility were conducted by the Helmholtz Zentrum Munchen (HZM) until the facility was trans­ferred to the BfS in 2009. From its initiation until 2009, Asse was regulated under German mining laws.

Research and experimental work on remotely handled ILW disposal started in the summer of 1972 and continued until waste disposal practices ended in 1978. From 1971 until 1978 the facility was also used to store a major part of the LLW and ILW produced in the Federal Republic of Germany. Altogether 125,787 drums and waste packages containing RAW were emplaced in the mine (BfS, 2011f). The layout of the Asse facility including chambers containing RAW is shown in Fig. 14.4.

The AtG was amended in 1976. The amendment implemented a licensing (i. e., plan approval) process for RAW storage and as a result waste storage practices were discontinued in 1978. At the time, as no additional RAW was being transferred to the site, German mining law continued to provide the legal basis for the operation of the facility as an underground research labo­ratory (URL). After phasing out of the disposal practices in 1978, the facil­ity continued to be used as an underground research laboratory with a major focus on the development of disposal technologies for heat­generating waste.

In 1995, after research and development came to an official end, backfill­ing of the former mining chambers in the southern flank of facility was initi­ated along with efforts to evaluate the long-term safety of the former mine. However, research was allowed to continue as long as related activities did not interfere with mine closure operations (Kappei, 2006).

Although the facility was initiated as a URL, because of the disposal practices that were conducted concurrent with research, the facility became

by default a repository. It has since been recognized that the operation and regulation of Asse under mining law did not provide an adequate regula­tory framework to manage and close the facility. On 4 September 2008, the BMBF, the BMU and the Lower Saxony Ministry for the Environment and Climate Protection (Niedersachsisches Ministerium fur Umwelt und Kli — maschutz, NMU) jointly agreed that the facility would be closed under the Atomic Energy Act. On 1 January 2009, transfer of the facility to the BMU under management of the BfS was completed.

Despite legal and political issues surrounding the Asse facility today, considerable experience and information was gained during the period of its operation. This experience and the tests that were conducted at Asse resulted in improved waste handling practices and technologies, as well as an improved understanding of salt as a host rock and engineered barrier system behaviour. Several national and international research studies were conducted at the URL. Examples include the following:

• a cooperative research programme with the US Department of Energy examined brine moisture migration, thermal mechanical response of salt, and material corrosion studies;

• drilling optimization studies were conducted as part of the Commission of European Communities COSA Project;

• the longest running drift-scale thermal simulation study was initiated by the Karlsruhe Institute of Technology (KIT) and later expanded and finalized under the European Union sponsored multi-national BAMBUS I and BAMBUS II projects, which included dismantling and retrieval exercises.

The BAMBUS projects were the last significant research conducted at the facility (Bechtold et al, 2004). Upon assuming operational responsibility for the Asse repository in January 2009, the BfS conducted a comparative study to assess the effectiveness of the various closure options. The options investigated included:

• retrieval: removal of waste from the mine for emplacement in another disposal facility

• relocation: construct and license a repository in deeper sections of the salt dome.

• complete backfilling: complete backfilling of all of the subsurface cavi­ties with concrete and installation of sealing systems in shafts and drifts at appropriate geological intersections.

After evaluation of the result of the comparative assessment, published in January 2010 (BFS, 2010), the BfS selected retrieval as the preferred option for final closure of the facility and is currently in the process of elaborating technical processes and requirements to achieve this goal.

Regulation and industry practice have evolved to reflect the principles of radiological protection and practicability of implementing options. This section is primarily aimed at the civil nuclear sector. Defence sites and wastes are generally managed in a similar way, although formal require­ments identified for the civil nuclear industry do not extend to defence activities. However, it is the policy of the Ministry of Defence (MoD) to meet standards equivalent to them where practicable.

Construction of this 1,230 MW station started in 1980 and it was commis­sioned in 1988. It is situated near Dunbar in East Lothian (Fig 17.1) It is currently scheduled to operate until 2023 (EDF Energy, 2010).

Its operational waste management processes and also its decommission­ing strategy are the same as described for Hunterston B. Defuelling and preparation for care and maintenance is planned to be undertaken by around the early 2030s with the long-term secure care and maintenance period then starting and continuing until around 2110. The decommission­ing waste management strategy is the same as Hunterston B but the esti­mated LLW that would be produced is higher and the ILW lower than for

Hunterston B (see Tables 17.2 and 17.3). Advances in the design of Torness, the later station, enabled the generation of ILW to be limited.

A dual regulatory framework exists for mixed waste, which is waste that the EPA considers to be hazardous and radioactive. The EPA or authorized states regulate the hazardous waste component and the NRC, NRC

Agreement States, or DOE regulate the radioactive component. The NRC and DOE regulate mixed waste radiation hazards using Atomic Energy Act of 1954 (AEA) authority. The EPA regulates mixed waste chemical hazards under its Resource Conservation and Recovery Act (RCRA) authority. The NRC is authorized by the AEA to issue licenses to commercial users of radioactive materials.

The EPA issued regulations in 2001 that apply to:

• storage at the generator site or another site operating under the same license

• treatment in a tank or container at the generator site or another site operating under the same license

• transportation to a licensed treatment facility or LLW disposal facility

• disposal at a licensed LLW disposal facility, as long as the waste meets RCRA treatment standards for hazardous constituents.

The EPA has also established National Emission Standards for Hazardous Air Pollutants (NESHAPs) under the Clean Air Act for airborne radionu­clide emissions from a variety of industrial sources. Various subparts apply to underground uranium mines, inactive uranium mill tailings piles, and active uranium mill tailings piles, respectively.

19.1.1 Radioactive waste (RAW) policy

The Government of Canada has policies, legislation and responsible organi­zations that ensure safe management of radioactive waste in Canada. The Government of Canada’s Policy Framework for Radioactive Waste consists of a set of principles governing the institutional and financial arrangements for management of radioactive waste (Natural Resources Canada, 1996). A key principle within the Policy Framework is that waste generators and owners are responsible, in accordance with the principle of ‘polluter pays’, for the funding, organization, management and operation of long-term waste management facilities and other facilities required for their wastes. The Policy Framework recognizes that arrangements may be different for the different categories of radioactive waste in Canada. In the case of nuclear fuel waste, the Government of Canada determined that it would be in the best interests of Canadians to have a national long-term management approach. In 2002, the Government of Canada brought into force the Nuclear Fuel Waste Act (NFWA), which outlines a process for the development and implementation of a long-term management approach for Canada’s nuclear

612

fuel waste and required that an organization, the Nuclear Waste Manage­ment Organization (NWMO), be established to carry out the work.

All radioactive waste generated on the Necsa site is still stored there. However, on 7 May 2011, the first shipment of LLW (Fig. 20.7) was disposed of at Vaalputs, and as this operation will take place over many years, it is assumed that some of these waste classes will continue to be stored for at least another 10 years at the Necsa site. Conditioning of this waste should therefore allow for storage at Necsa for a period of at least 10 years. Con­ditioning of HLW should ensure compliance with long-term interim storage at the Necsa or Vaalputs site (50 years).

20.1.3 National radioactive waste management system

Radioactive waste management as interpreted by Necsa is structured as presented in Fig. 20.8 . Radioactive waste management in South Africa is structured and implemented by including the applicable sections from the various National Acts, i. e National Environmental Management Act (No. 107 of 1998), The National Nuclear Regulator Act (No. 47 of 1999), the Nuclear Energy Act (No. 46 of 1999), the Hazardous Substances Act (No. 15 of 1973), the National Water Act (No. 36 of 1998), etc. On a strategic level, the NRWMPS expresses the national commitment towards the man­agement of RAW in order to ensure a coordinated and cooperative approach to RAW management and to provide a national strategy and framework for the development of future waste management plans.

Site-specific waste management plans are then developed based on the directives and guidelines provided by the NRWMPS. The purpose is to create an optimized and sustainable plan that provides for acceptable waste stream-specific pre-disposal management prescriptions for the identified waste end-points. The waste management plan is supported by the waste management system elements aimed at ensuring and demonstrating that waste management practices comply with requirements. The system renders the support structure for the implementation of the site-specific waste man­agement plans. It provides for pre-disposal management standards and integrates the relevant legal, regulatory and strategic management require­ments that will eventually lead to the National Nuclear Regulator (NNR) approval of the system. Elements of the System include: site waste manage­ment principles, site waste management responsibilities, quality assurance and site waste management processes and pre-disposal standards.

Facility-specific waste management programmes (FSWMP) are devel­oped from the waste management plan. The purpose of this is to ensure and demonstrate compliant and consistent waste management practices at each facility. These programmes are developed by integration of the relevant plan, system, operational and regulatory requirements.

The general radioactive waste management process is demonstrated in Fig. 20.9 , which shows the typical interactions between waste generators, pre-disposal and disposal operators, as well as the demarcations existing between them. It should be noted, however, that Fig. 20.9 presents the process for general waste streams. In the case of special waste streams, the waste generators are responsible for some or all of the pre-disposal steps.

A small-scale underground research laboratory, KAERI Underground Research Tunnel (KURT) at KAERI in Daejeon, was constructed to develop a Korean disposal system for the HLW repository, including spent fuels, between March 2005 and November 2006. The KURT, with an access tunnel and two research modules, as shown in Fig. 21.8 , is located in a mountainous area inside the KAERI territory. The KURT, has a total length of 255 m with a 180 m long access tunnel and two research tunnels 75 m long in total. The maximum depth of 90 m could be effectively achieved by select­ing the tunnel direction to the peak of a mountain. The horseshoe shaped tunnel, 6 m wide and 6 m high, is located in a granite rock body (Fig. 21.8). Regardless of limited applications of KURT, which only handles naturally occurring radionuclides, the KURT facility will be a major infrastructure for validating the safety and feasibility of the suggested disposal system by various in-situ experiments:

1. Single hole heater test in rock.

2. THM (thermal-hydraulic-mechanical) behavior of engineered barrier systems (EBS).

3. EDZ (excavation disturbed zone) characteristics and mechanical stabil­ity of rock.

4. Retardation of solute migration through fractured rock.

5. Site investigation techniques.

6. Hydrogeological and geochemical baseline data (Kwon et al., 2009 ).

The current 10-year plan for mid — and long-term nuclear R&D on HLW disposal was accepted by the AEC in 1997. This plan includes a program for development of a Korean repository for HLW disposal and for the associated system performance assessment. After completion of the

combined research output of this 10-year study, the Korean government will define the direction and prioritization of further R&D activities for HLW disposal. Since 1997, KAERI has been developing a permanent dis­posal facility for HLW and a total system performance assessment (TSPA). Its current R&D activities are focused on the preliminary conceptual design of the Korean Reference Disposal System (KRS), development of the key technologies, and geo-environmental studies to confirm the KRS’s safety, as shown in Fig. 21.9. Currently, the four major projects underway at KAERI are:

1. repository system development;

2. a TSPA;

3. geo-environmental science research; and

4. construction and operation of a KAERI underground research tunnel (KURT) to demonstrate the KRS ’s performance relevant to the func­tional criteria established in the disposal concept (Fig. 21.8).

Treatment of the gaseous waste from enrichment plants removes fluoride and radioactive particles before discharge into the environment. The off-gas from centrifuges is typically filtered with NaF filters, alumina filters, and HEPA filters, and then discharged through a stack after radioactivity measurement.

In the enrichment plants, small amounts of liquid waste are generated from floor drainage and detergent wastes. These wastes are typically treated by flocculation using a flocculate agent such as polyaluminum chloride, and discharged into the environment.

Treatment of the solid waste is aimed at volume reduction for storage. Combustible wastes are incinerated, and then placed in 200 L storage drums. Incombustible wastes are placed directly in appropriate containers, and stored at the facilities.

25.1.1 Waste classification

Radioactive wastes were originally classified into high, medium and low level, but as the nuclear industry has progressed, additional categories have been introduced and some have been sub-divided (Table 25.1) . Having well-defined classifications is important, as these frequently form the basis on which national governments base their legislation relating to the disposal routes for radioactive wastes.

Several waste categories are clearly defined by their activity levels based on either the a or p/у activity. High level waste is defined by its

heat-generating ability and the IAEA have recently revised their definition by removing the 2 kWm-3 threshold (IAEA, 2009).

In the UK, low volume VLLW can be disposed of safely to unspecified destinations with municipal, commercial or industrial waste, whereas high volume VLLW can only be disposed of to a specified landfill site. For wastes containing solely tritium or carbon-14, the limits are increased by an order of magnitude.

Wastes arising from nuclear weapons programmes can fall into all of the above categories, but the three of specific interest are HLW, TRU and ILW. In the early days, many of the candidates investigated for the immobiliza­tion of commercial wastes were considered, but currently ILW is generally compacted and cemented into steel drums, whilst HLW and some ILWs are vitrified in borosilicate glass; however, some of the newer wastes may require alternative immobilization techniques to be developed. Disposal routes already exist for LLW, which for the UK is in a special site at Drigg in Cumbria.