NORM means wastes containing, or contaminated, with naturally occurring materials at a concentration or radioactivity higher than the relevant regu­latory level and which is expected to have no further use. These wastes arise principally from the mining and milling of rare-earth minerals and the production of phosphates among others. The radioactivity in such kinds of wastes is mainly from radioactive materials associated with raw materials and of quite large volume.

Spent fuel (SF)

The amount of Chinese SF was about 1,000 t from light reactors in 2010. It will be 2,000 t in 2015 and then 1,000 t produced each year from 2015 to 2020. However, a single CANDU reactor which will be in operation in Qinshan III will give 200 t SF each year when it is in operation. Since 2010, SF from China’s LWRs is being reprocessed first in a small pilot plant, fol­lowed by vitrification and eventually geological disposal.

The Fukushima Daiichi reactors are six boiling water reactors (BWR) of an early 1960s design supplied by GE, Toshiba, and Hitachi with power ranges from 460 MWe to 1,100 MWe. They came into commercial operation between 1971 and 1975. Four units (1-4) are of Mark-I type containment, which is the first generation of BWR design (Fig. 24.1). At the time of the accident, the units and central storage facility contained the fuel assemblies as shown in Table 24.1.

Spent fuel —————

pool

Reactor service — floor

Concrete reactor building

Reactor pressure vessel

Primary containment drywell

Suppression pond wetwell

The geology of the western region of the NNSS consists primarily of thick sequences of ash-flow tuff, lava, and volcaniclastic rocks deposited during episodic volcanic cycles associated with the formation of as many as six coalesced caldera centers from 15 million to 9 million years ago (the South­west Nevada Volcanic Field; Byers et al., 1976; Sawyer et al., 1994). These caldera centers are localized in the north-northeast trending Amargosa Desert rift zone (Wright, 1989; Carr, 1990; Fridrich, 1998), a major north — northeast trending structural trough identifiable using gravity and seismic reflection data (Healey et al., 1980; Brocher et al., 1998). The thick volcanic section in the Amargosa Desert rift zone locally replaces the carbonate aquifer as the primary pathway for regional groundwater flow. The carbon­ate aquifer is either missing, too deep in the stratigraphic section and/or impermeable from contact metamorphism associated with caldera pluton­ism to transmit significant quantities of groundwater. Regional groundwater flow in the western volcanic sequence is topographically controlled and driven by the increased recharge at higher elevations, primarily from eastern Pahute Mesa (Blankennagel and Weir, 1973 ; Laczniak et al., 1996; SNJV, 2009a; Fenelon et al., 2010).

The Miocene volcanic rocks form high elevation plateaus of welded and nonwelded ash flow sheets concentrically flanking their source calderas. This plateau topography remains preserved where basin-range deformation has locally faulted but has not significantly extended and disrupted the mesas (Pahute and Rainier mesas and Yucca Mountain) (Fig. 26.2). This layered sequence of outer caldera ash-flow sheets is replaced locally by thick sequences of densely welded ash-flow tuff and intrusive rocks within caldera depressions. This pattern of extra — and intra-caldera rock sequences is complicated in the northern part of the Amargosa Desert rift zone by multiple stages of caldera formation. Younger calderas disrupt and bury the structure and volcanic rock assemblages of older calderas.

Spatial changes in lithology and thickness of the volcanic rocks of the western volcanic highland are significant (laterally and vertically heteroge­neous), and they are locally affected by secondary alteration (zeolitization), burial diagenesis and/or hydrothermal activity. These lithologic and altera­tion features strongly affect the hydrologic properties of the rocks (tend to reduce conductivity) and form complex inter-layered aquifers and confining units locally offset or truncated by caldera structures and/or extensional faults. Groundwater flow can be rapid (tens of meters per year) within zones of higher density cooling joints within welded tuff and rhyolite lavas, both augmented by flow along faults; groundwater flow is much slower (one meter per year or less) through altered volcanic rocks and/or zones of matrix-dominated permeability.

For transportation and interim storage, Germany developed and licensed the CASTOR® cask system. This system includes a number of different variants based on the intended contents. However, in general all CASTOR® containers consist of a double-shell design sealed with two separate end-cap sealing systems. The cask body consists of a large cylindrical 30-40 cm thick — walled casing made of ductile cast iron steel. The interior of the CASTOR® container is nickel plated. For neutron moderation, axial boreholes are distributed uniformly in the cask wall to accommodate moderator rods. The

bottoms of the containers are sufficiently thick to provide gamma and neutron shielding. The lid system consists of a double-barrier sealing system upon which a third protective cover is placed during storage. During trans­portation, both the lid and the bottom ends are protected by large steel — plate shock absorbers. The exterior design of most of the CASTOR® containers incorporates cooling fins designed to radiate access thermal energy from SNF or HLW that are still generating heat. The casks are loaded under water. Today the most widely used CASTOR® containers are the types CASTOR® V/19 (for the contents from 19 spent fuel assemblies used in pressurized water reactors) and CASTOR® V/52 (for the contents from 52 spent fuel assemblies used in boiling water reactors). These contain­ers are approximately 6 m long with a diameter of approximately 2.5 m and weigh approximately 125 tonnes when fully loaded (GNS, 2011b ; BAM, 2010). Feasibility studies are currently under way regarding the potential use of the CASTOR® cask for geologic disposal. A typical CASTOR® is shown in Fig. 14.2.

Experience has shown clearly that the initial characterization of sites is paramount. All past projects that have been engaged on the basis of inad­equate initial characterization have ultimately led to hard to overcome technical difficulties and additional costs far higher than the savings attained on the initial characterization of the site. No concessions should be made on the initial characterization of the site. ANDRA’s agents should also not intervene for site remediation on a site that has not been sufficiently characterized.

The Scottish government is a joint sponsor with the UK government and other devolved administrations of the UK-wide policy for the management of LLW published in 2007 (UK Government, 2007). This policy was imple­mented by an enabling strategy developed by NDA in 2010 (UK Govern­ment, 2010) of which the Scottish government was again a joint sponsor. Consequently there is no difference in approach to LLW management in Scotland than anywhere else in the UK, and LLW generated in Scotland is routinely transported to the LLWR in Cumbria for disposal. The exception is LLW generated at Dounreay which is disposed of on-site and described in detail in Section 17.6.

The DOE is responsible for and performs most of the SNF and RAW man­agement activities for government-owned and — generated waste and materi­als, mostly located on government-owned sites. These activities include managing SNF remaining from decades of defense reactor operations, which ceased in the early 1990s. Since then, the DOE has safely stored the remaining defense SNF and SNF generated in a number of research and test reactors. The DOE also provides safe storage for the core of the decom­missioned Fort St. Vrain gas-cooled reactor and the core of the Three Mile Island Unit 2 reactor damaged in a 1979 accident.

The DOE has a system for managing government SNF and radioactive waste. This includes numerous storage and processing facilities (treatment and conditioning), such as operating disposal facilities for LLW and TRU waste. Other waste management treatment and disposal systems support cleanup and closure of decommissioned facilities no longer serving a DOE mission.

The United States also continues activities to remove and/or secure high — risk nuclear and radiological materials both domestically and internation­ally. Part of this initiative is continuing the program of accepting US-origin foreign research reactor SNF and returning it to the United States for safekeeping and recovery of disused sealed sources.

Until a repository for permanent disposal becomes available, the DOE will store canisters of solidified high-activity tank waste onsite. The stabilized product of LAW treatment at WTP and at Saltstone (facilities for safely stabilizing and disposing of low-level radioactive liquid salt wastes) will be disposed of onsite in stainless steel containers at Hanford and in concrete vaults at SRS, respectively. These wastes contain only 1-10% of the radio­activity present in the tank waste.

Tanks at INL and Hanford contain liquid wastes that are not radioactive wastes generated from the reprocessing of SNF. The DOE plans to pursue alternative but safe, compliant, and more cost-effective disposal paths for these wastes on a case-by-case basis. For example, some may meet the cri­teria for disposal at the WIPP.

High-level waste (HLW)

High-level waste is heat-generating waste (typically above 2 kW/m3 or waste that needs to be managed in terms of its heat-generating properties over long durations) with high long — and short-lived radionuclide concentrations which include fission products and actinides. SF pellets and element sections from post-irradiation testing of pressurized water reactor (PWR) fuel, waste from Mo production and SF from the SAFARI reactor are retained waste that is regarded as potential HLW. Potential HLW is retained in the facilities of origin or stored in interim storage facilities in accordance with facility-specific nuclear authorizations. Potential HLW with proven heat — generation capacity of less than 2 kW/m3 or waste that does not need to be managed in terms of its heat-generating properties may be considered for re-classification as ILW. Waste types with long-lived radionuclide concentra­tion levels that would result in an inherent intrusion dose of more than 100 mSv/a, after an institutional control period of 300 years, shall be managed as HLW.

HLW that is removed from authorized containment systems shall be processed to ensure a solid waste form in a waste package that is suitable for handling, transport and storage for a period of 100 years. Disposal of HLW is limited to a high degree of containment and isolation from the biosphere over long time periods, which is obtainable by regulated deep geological disposal (hundreds of metres).

The safe management of RAW is recognized as an essential national task for sustainable generation of nuclear energy and for energy self-reliance in South Korea. Since the early 1980s, the Korean government has attempted to prepare a disposal site for safe management of RAW but failed to secure one due to lack of public consensus and acceptance. In this context, the Atomic Energy Commission (AEC) of the Korean government, the highest decision-making body for nuclear energy policy, approved the ‘National

Radioactive Waste Management Policy’ at the 249th meeting held on Sep­tember 30, 1998. This policy stipulated that a LILW facility would be con­structed and operated by 2008 and a centralized spent fuel interim storage facility by 2016. The key principles of the national policy on radioactive waste management are as follows:

• direct control by the government

• safety as top priority

• minimization of waste generation

• ‘polluter pays’ principle

• transparency for site selection process.

However, a revision of the government policy was made at the 253rd AEC meeting on December 17, 2004, after the government failed repeatedly to find a candidate site for the radioactive waste management complex. There­fore, a new government plan for radioactive waste management was announced, basically to separate the sites for the LILW disposal facility and the spent fuel interim storage facility instead of constructing both facilities on one site. The LILW disposal facility is now being constructed in Gyeongju after local referenda. Conversely, the key decision to directly dispose of or recycle spent fuel has not yet been made in Korea. Spent fuel is currently stored at reactor sites under the responsibility of Korea Hydro and Nuclear Power Co. (KHNP), because the 253rd AEC meeting stipulated that the national policy for spent fuel management will be decided later, taking account of domestic and international technological developments.