Waste disposal repositories

In democratic societies, public acceptance is a prerequisite for realizing high level waste disposal repositories. Perspectives are accordingly dependent on the outcome of the related public discussions in which anti-nuclear movements play an important role. Sometimes in combination with political parties, such movements have become today a political force which can not be neglected. What they have to say has to be seriously analyzed and it is important to establish a proper dialogue Even with the understandable intention to avoid unnecessary confix ntation, one must not avoid controversial and emotional debates involved. 

For nuclear waste disposal, in a site such as Yucca Mountain, if the maximally exposed individual receives the proposed annual limit of 0.15 mSv, present estimates (based on the linearity hypothesis) suggest a 0.00 1 % risk of an eventual fatal cancer. The maximum dose is reached only if the wastes are dissolved in a small volume of water, and therefore only a limited number of people would receive this dose. If this number were as high as 1000, the implied toll for Yucca Mountain neighbors would be one cancer fatality per century per repository site.19 This toll would not start for many centuries, when the waste canisters begin to fail, and it not unreasonable to expect that cancer prevention and treatment will be much improved by then. Ignoring this prospect, and assuming many repositories and some doses above the prescribed limit, it still appears that the expected toll would be well under a thousand deaths per century. 

Progress in the establishment of a permanent waste repository, presumably at Yucca Mountain, within a framework of reasonable waste disposal standards. 

The issue of brine migration in a thermal gradient was previously mentioned in the discussion of thermal effects and canister motions. This phenomenon is not an issue for TRU waste disposal but must be considered for HLW repositories in salt. Since its main effects could be to enhance high-level waste canister motion through "weakened" salt, to corrode the waste canister and to provide a leachant for the waste, the... 

Nuclear waste. The nuclear waste disposal scheme remains to be finalized. The Yucca Mountain project in Nevada has made good advances recently, and when licensed it can provide a destination for the spent fuel accumulating at the plant sites. The development of a closed fuel cycle that involves the extraction and use of the fissile contents from the irradiated fuel would reduce the long-lived radioactivity associated with the waste to be sent to the repository. 

As shown previously, radioactive hazards associated with SF and HLW decrease exponentially over time (see Figure 2). After 10" -10 yr, the risk to the public of a nuclear waste disposal vault approaches that of a high-grade uranium ore deposit and is less than the time invariant toxicity risk of ore deposits of mercury and lead (Langmuir, 1997a). The new ERA standard for nuclear waste repositories seeks to limit exposures from all exposure pathways for the reasonably maximally exposed individual living 18 km from a nuclear waste repository to 0.15mSvyr (15 mrem yr ) (US EPA, 2001). For comparison. 

Among aqueous species, the most important corrections are for stabilities of the complexes U02(0H)2 and U(OH)4, which are apparently less stable than proposed by Grenthe et al. (1992) by about 2.4 and 10.6 kcal/mol, respectively. At near neutral pH s, stabilities of these complexes define the minimal respective solubilities of U(VI) and U(IV) minerals in groundwater. These errors have important implications to nuclear waste disposal, where the solubilities of U(IV) and U(VI) minerals are being used to define maximum possible uranium concentrations that might be released from a geological repository for nuclear waste (cf. McKinley and Savage 1994). 

For full public acceptance of nuclear power, a number of issues must be addressed, including waste disposal, reactor safety, economics, and nonproliferation. All of these issues depend on the fuel cycle that is used, but for any fuel cycle a geological repository will be needed for high-level waste storage. What will differ are the nature, hazard, half-life, and volume of the waste. 

The performance of a geological repository for nuclear waste is influenced by many processes. Determination of whether the total system will comply with regulatory requirements necessitates consideration of all components of the systems and the effects of linking all the components together. This linkage is important because it allows each component to be viewed in the context of the behavior of the entire system. Hence, the concept and methodology of Total System Performance Assessment (TSPA) is widely used in nuclear waste disposal (Figure 2.2). 

The overall emphasis of geological radioactive waste disposal is to site and construct the repository facility and to demonstrate its safety. There are several couplings affecting repository performance, and identifying processes and... 

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