[en] PRESTO II is an improved version of the multigroup source-sink programme PRESTO I written in 1967. A major development has been the re-formulation of the flux calculation to produce a more accurate treatment of the dipole components of neutron flux. New influence functions have been introduced to permit detailed editing of the azimuthal components of flux at the channel boundaries. In conjunction with data generated by the auxiliary code QUAVER, PRESTO II calculates the azimuthal variation of fission power within individual layers of the fuel clusters. The generation of monopole and dipole channel boundary conditions for PREST II by QUAVER is now based on input data from the WIMS lattice code, which is accepted standard for SGHW reactor calculations. These developments of PRESTO, together with associated improvements in QUAVER, have been required to permit detailed analysis of cluster tilt measurements in zero energy reactors, and to provide benchmark calculations of cluster tilt for commercial reactor designs. (author)

[en] W-MONTE provides a multi-group model of neutron transport in the exact geometry of a reactor lattice using Monte Carlo methods. It is currently restricted to uniform axial properties. Material data is normally obtained from a preliminary WIMS lattice calculation in the transport group structure. The SGHWR version has been required for analysis of zero energy experiments and special aspects of power reactor lattices, such as the unmoderated lattice region above the moderator when drained to dump height. Neutron transport is modelled for a uniform infinite lattice, simultaneously treating the cases of no leakage, radial leakage or axial leakage only, and the combined effects of radial and axial leakage. Multigroup neutron balance edits are incorporated for the separate effects of radial and axial leakage to facilitate the analysis of leakage and to provide effective diffusion theory parameters for core representation in reactor cores. (author)

No abstract available

[en] A nuclear power plant operating with both a thermal and a fast reactor housed in the same containment building is discussed in this invention. The fuel elements are transferred between the two reactors using a charge/discharge machine. As the enrichment of the fuel elements in the thermal reactor falls (and hence also the reactor reactivity), the fuel elements are transferred to the fast reactor to permit re-enrichment of the isotopes which are fissionable by thermal neutrons. The fuel elements are then replaced in the thermal reactor. The advantage of obtaining a higher breeding ratio in the fast reactor by using a gaseous rather than a liquid metal coolant is also discussed. (U.K.)

No abstract available

[en] The nuclear industry is moving towards a period of ever increasing emphasis on business performance and profitability. Safety has, of course, always been a major concern of management in the nuclear industry and elsewhere. The civil aviation industry , for example, has had a similar concern for safety. Other industry sectors are also developing safety management as a response to events within and outside their sectors. In this paper the way that the risk management process as a whole is being addressed is looked at. Can we use risk management, initially a safety-orientated tool, to improve business performance? (author)

[en] 1 - Nature of physical problem solved: Two neutron group diffusion equations for a square mesh in x-y geometry are solved to yield a power distribution. Burnup for one time step is simulated by interpolation in a library of two-group cross sections which forms part of the problem data. It is assumed that the power distribution is invariant during one time step, at the end of which a re-calculation of flux and power follows automatically. Burnup proceeds in a succession of time steps and a number of fuel management options are available. 2 - Method of solution: Standard finite difference methods are used. 3 - Restrictions on the complexity of the problem: The programme is restricted to two neutron groups. Limits on the number of mesh points are as follows - IBM 7030 61 x 61; IBM 7090 32 x 32; see also AEEW - R.425

[en] Advanced reactor designs are now being actively pursued in many centres throughout the world for both economic and safety reasons. The Safety and Reliability Directorate of AEA Technology has reviewed these designs to see if they pose any new issues for safety analysis, which will require new methods or data to resolve. In order to identify potential accident sequences in new designs, a generic logical tool for accident sequence identification has been developed. Also, the safety of these designs has been found to rest more on analysis of such natural processes as natural convection. This may call for more detailed models and experimental verification. These apart, no fundamental difficulties have been found. Simplified designs should make it easier to demonstrate the required degree of safety more transparently, and many of the new designs can retain the benefit gained from operating experience with existing plant if the departures from current practice are not too radical. (author). 1 fig

[en] Some of the practical, legal and regulatory issues which the board of directors of a target company should bear in mind in their deliberations concerning a take-over bid are reviewed. Directors of such companies will require compliance with and adherence to standard legal and regulatory rules of conduct. Developing a team to deal with the myriad details of a take-over, acquisition or merger, preparing and compiling and maintaining a manual of relevant information are highly recommended. Fiduciary duties of directors and its relevance to mergers and acquisitions are illustrated by reference to a number of recent actual court cases involving these issues. Relevant Canadian and U.S. Case Law is reviewed. It is emphasized throughout the paper that take-over transactions, mergers and acquisitions are complex and time consuming processes. It is essential and customary for senior management to be active participants in most merger and acquisition matters to provide the strategic input which drives the efforts of all involved. Equally important is to establish appropriate governance practices and to prepare and equip the corporation's mergers and acquisitions team in advance, should such events arise on short notice by design or otherwise. 38 refs

[en] A detailed example is presented of the way in which probability analysis techniques may be applied to a typical 10 MW MTR. The steps necessary to enable an assessment of the probability and consequences of an accident sequence are outlined. Some detailed examples are given of the ways in which probabilities for particular accidental occurrences may be assessed from an analysis of the components of a system and a knowledge of their individual failure characteristics. (author). 10 refs, 5 figs, 4 tabs