Untitled

Abstract

Much has been written about the development and application of quantitative methods for estimating under uncertainty the long-term radiological performance of underground disposal of radioactive wastes. Until recently, interest has been focused almost entirely on the technical challenges regardless of the role of the organization responsible for these analyses. Now the dialogue between regulators, the repository developer or operator, and other interested parties in the decision-making process receives increasing attention, especially in view of some current difficulties in obtaining approvals to construct or operate deep facilities for intermediate or high-level wastes. Consequently, it is timely to consider the options for regulators' review and evaluation of safety submissions, at the various stages in the site selection to repository closure process, and to consider, especially, the role for performance assessment (PA) within the programs of a regulator both before and after delivery of such a submission. The origins and broad character of present regulations in the European Union (EU) and in the OECD countries are outlined and some regulatory PA reviewed. The issues raised are discussed, especially in regard to the interpretation of regulations, the dangers from the desire for simplicity in argument, the use of regulatory PA to review and challenge the PA in the safety case, and the effects of the relationship between proponent and regulator. Finally, a very limited analysis of the role of PA in public hearings is outlined and recommendations are made, together with proposals for improving the mechanisms for international collaboration on technical issues of regulatory concern.

The physical and chemical structure of hot molecular cores

“…The scale size Θ beam is simply taken as 0.25 pc which corresponds to the angular size of 13" at the distance of 3.7kpc, based on the half power beam width of the James Clerk Maxwell Telescope (JCMT) at 345 GHz (cf. Thompson et al 1999). While the data of most molecular lines we use in this paper are from single radio telescope observations such as the JCMT, the NH 3 data is from the Very Large Array observation whose synthesized beam size is about 1"3 (Heaton et al 1989).…”

“…( 7) with the distance from the clump centre, r ′ = r − r off replacing r. The results at t = 10 4 yr are listed in Table 2. Parameters of Θ beam = 0.25 pc and r off = 0.4 pc are adopted for comparing the results with observations toward the halo associated with G34.3+0.15 by Thompson et al (1999), which are also included in Table 2. For comparison, the molecular column densities calculated around the clump centre by Eq.…”

Observations of chemical differentiation in clumpy molecular clouds

“…Since we have observed single transitions in C 18 O, SO and HC 3 N, and detect only one or two CH 3 OH transitions in a large fraction of the spectra, we determine a lower limit to the column density [48]. In this procedure, the rotation temperature can be approximated as T rot = 2Eu 3k for non-linear molecules (CH 3 OH), and as T rot = Eu k for linear molecules (C 18 O, SO and HC 3 N).…”

Cyanopolyynes in hot cores: modelling G305.2+0.2

“…Observations of hot cores include molecular line and dust continuum emission, and some of the chemical core models, along with radiative transfer calculations, have proven useful in reproducing observed column densities (e.g., Millar, Macdonald & Gibb 1997;Kaufman et al 1998;Thompson et al 1999;Doty et al 2002). Chemical models have been developed that include a pre-stellar phase or initial conditions assuming the presence of evaporated grain mantle species (e.g., Brown, Charnley & Millar 1988;Millar, Herbst & Charnley 1991;Charnley, Tielens, & Millar 1992;Caselli, Hasegawa, & Herbst 1993;Millar, Macdonald & Gibb 1997;Viti & Williams 1999;Doty et al 2002;Nomura & Millar 2004;Wakelam et al 2004).…”