All of the British Magnox nuclear power stations will close before 2010. All 11 Magnox power stations have exceeded their original accounting lifetime of 25 years and together they have accummulated almost 1000 reactor years of safe operation. This paper reviews three of the technical issues that have arisen during operation, with the aim of identifying useful lessons and good practice that can be utilised when developing new reactors. The approaches to dealing with these issues are described. Some of the improvements that ham been made to operational efficiencies are also described.
Nuclear power has many advantages, among them at least two that directly flow front the uranium energy source itself-the low cost of the natural uranium. as a proportion of overall generating costs, and the small amount of fuel necessary to provide very large amounts of energy. However, some recent Publications have promoted the view that limited supplies of natural uranium are the Achilles heel of nuclear power as the sector contemplates a larger contribution to future clean energy. This paper summarises some of the perspectives and analysis that support the following conclusion: uranium supply, like that for other metals, is economically sustainable. This means that normally functioning metals markets and technology change provide the drivers to ensure that supply at costs affordable to consumers is continuously replenished, both through the discovery of new resources and the redefinition (in economic terms) of known ones.
A scheme for earlier and clearer communications with the Health and Safety Executive (HSE) and the Environment Agency (EA) oil jointly regulated issues has been developed across the nuclear industry over the past two years. The matched pair of industry and regulators' 'Working Together' documents was published in January 2003. In the United Kingdom Atomic Energy Authority (UKAEA), the scheme is being put into practice through the issue of Initial Regulatory Notifications (IRN) of various projects and issues, to capture key regulatory topics and prompt regulators' initial responses. The IRN may be based oil a safety and environment overview, report or may be a precursor to it. Positive responses, ill line with the Working Together documents, were received from HSE and the EA, following receipt of the first three UKAEA IRNs.
This paper addresses four inter-related topics of current concern: (i) the relationship between man-made and natural radiation; (ii) the uncertainties in predicted consequences following low dose irradiation; (iii) the scope for using a Properly Prioritized Precautionary Principle (P4); and (iv) why unobservable effects should not be a cause of concern.
The Alberta oil-sands bitumen deposits comprise one of the largest sources of hydrocarbon in the world, and have emerged as the fastest-growing, soon to be dominant, source of crude oil in Canada. Although the oil industry has made great strides in improving the effectiveness of gathering this resource, the main challenge that remains is the large quantity of energy needed in the process of extracting the oil and upgrading it to commercial levels. However, over the past few years, developments in oil-sands extraction technology, and developments in CANDU technology through the advanced CANDU reactor, (ACR(TM)), have converged so that a practical, economical match of nuclear energy to the oil sands is now available. This paper describes recent studies by Atomic Energy of Canada Limited (AECL) and by the Canadian Energy Research Institute (CERI) to look at the adaptation of the ACR design for use in the oil sands, in particular with regard to economic viability. Issues raised in these studies are discussed, along with priorities for further work.
The gas-turbine modular helium reactor (GTMHR) couples a high-temperature gas-cooled reactor (HTGR) with a Brayton power conversion cycle to produce electricity at high efficiency. It is based on HTGR technology developed over the past 40 years that includes the design, construction and operation of seven HTGR plants. The GTMHR satisfies the Generation IV goals of passive safety, good economics, high proliferation resistance, and improved environmental characteristics including reduced waste and better fuel utilisation than the current generation of nuclear power plants. Because of its capability to produce high coolant outlet temperatures (at least 850degrees C with potential for still higher temperature), the modular helium reactor system can also efficiently produce hydrogen by high-temperature electrolysis or thermochemical water splitting. The technology embodied in the GTMHR concept has high potential, with modest further development work, to meet the requirements for the next generation nuclear plant (NGNP) demonstration project planned to be built at the Idaho National Engineering and Environmental Laboratory (INEEL). The NGNP objectives are to demonstrate passive safety, licensing of new nuclear plants, use of the Brayton cycle for high-efficiency electricity generation and use of high-temperature nuclear heat for production of hydrogen.
The flow distribution and heat transfer characteristics in the McMaster nuclear reactor 18-plate nuclear,fuel assembly are investigated numerically using a commercial computational fluid dynamics code. The standard k-epsilon turbulence model together with a two-layer wall boundary model is applied. The code is first validated on a series of problems relevant to the reactor flow. It is then used to predict the flow and heat transfer in the nuclear fuel plate assembly. The predictions are compared to both experimental data and predictions from a one-dimensional thermal hydraulic code.
The nuclear industry is currently faced with the double challenge of maintaining and expanding the presence of nuclear energy in base-load electricity generation and the question of tackling the penetration of nuclear energy in other sectors of the energy market, in particular the hydrogen economy. This paper argues that for several more decades. water-cooled reactors, and particularly (LWRs), light-water reactors, will be the backbone for base-load electricity generation. Generation IV reactor types may enter this market in about 30 years from now, provided they become competitive with LWRs or are needed as a complement to LWRs to penetrate new energy markets such as hydrogen production and/or to stretch out uranium resources. It also discusses the issue of winning public acceptance for new nuclear build.
The United Kingdom Atomic Energy Authority (UKAEA) celebrated its fiftieth anniversary on 19 July 2004. Throughout this half-century the Authority has had an interesting and varied history, contributing much to UK science and the economy in many diverse ways. From its early central role of developing the UK's nuclear deterrent and nuclear power for the generation of electricity, the Authority, from the mid-1960s onwards, extended its R&D activities into non-nuclear fields, and broadened its links with businesses and universities. This paper reviews the UKAEA's considerable achievements, its current fusion research programme and the reshaping of its business parks, and ends by offering best wishes for the future.
The Chernobyl reactor accident in April 1986 caused the release to atmosphere of some 2 x 10(6) TBq, or more, of total fission/activation products. Estimates of deposition vary, although it is probable that about half the activity was deposited within 20 km of the release point, predominantly following two plume trajectories to the north and west. This resulted in the death of pine trees over 400 ha, the abandonment of up to 150 000 ha of agricultural land and the establishment of an exclusion zone extending to 30 km from the site. High levels of radionuclide contamination continue to prevail within the exclusion zone. Nonetheless, recolonisation has been widespread. Mixed deciduous woodlands, with a high proportion of birch (Betula spp.) and willow (Salix spp.), have become established in the forest areas, while agricultural land has succeeded to tall grassland and scrub. Field sites investigated in this study, during 2001 2003, exhibited external gamma dose rates varying from 0.1 muSv h(-1) to 140 muSv h(-1). Corresponding mean concentrations of (CS)-C-137 in the top 20 cm of soil varied from about 6 x 10(2) to 3 x 10(6) Bq kg(-1) dw (dry weight). Little impact is evident on populations of small mammals in these areas, either for species diversity or overall abundance, although there is a slight (not statistically significant) trend for increasing spleen weight in the bank vole with increasing levels of contamination. Previous suggestions that populations contain a preponderance of juveniles and sub-adults at the highest contaminated sites are not supported.
The AP1000 is a two-loop, 1150 MWe pressurised water reactor (PWR) with passive safety features and extensive plant simplifications to enhance construction, operation and maintenance. The AP1000 design is derived directly from the AP600, a two-loop, 600 M We PWR. The AP600 uses proven technology, which builds on over 30 years of operating PWR experience and received Final Design Approval from the United States Nuclear Regulatory Commission in September 1998 and Design Certification in December 1999. The AP600 meets all of the Electric Power Research Institute's Advanced Light Water Reactor Utility Requirements including the cost goals, and following a high-level review has also been shown to have broad compliance with the European Utility Requirements Document. Although the AP600 is the most cost-effective plant ready for deployment, it is still more expensive than the $1000/kWe overnight capital cost needed to compete in the United States and Europe today. In order to provide a cost-competitive nuclear power plant, Westinghouse has developed the power uprate of AP600 to at least 1150 MWe, while maintaining its current design configuration, use of proven components and licensing basis. A study has recently been completed in cooperation with British Energy which assesses the AP1000 reactor as an option for new nuclear build in the UK.
Following a request by the Department of Trade and Industry in 2002, the authors set up a series of meetings with green non-governmental organisations to gauge their views regarding the setting up of the Nuclear Decommissioning Agency. This paper summarises the outcome of those meetings, expressing greens' hopes and concerns and their recommendations for the future of the NDA.
BNFL Environmental Services has formulated updated proposals for the use of decision analysis in the development of decommissioning strategy. The proposals are based on the Department of Transport, Local Government and the Regions manual for practitioners on multi-criteria analysis, specifically multi-criteria decision analysis, as suited to complex problems with a mixture of monetary and non-monetary objectives. They take account of up-to-date academic methodology, the newly issued BNFL decision analysis framework for environmental decisions and a wide variety of other engineering, optioneering and optimisation processes. The paper also summarises legislative and company policy areas of importance to decommissioning strategy development. Higher-level generic reactor and site remediation strategies already exist. At the lower level, various generic decommissioning reference processes and project options need development. For the past year, Environmental Services has held responsibility to respond to the Nuclear Installations Inspectorates' quinquennial review, develop and maintain up-to-date strategies, institute the review of a selected number of key strategies, and respond to changing circumstances including stakeholder views. Environmental Services is performing a range of generic studies for selection of strategies and end-points as used for a variety of waste management and site care and maintenance preparations.
New legislation directly affecting the nuclear arena is on the immediate horizon at both European Union (EU) and UK levels. This paper looks ahead to the new legislation by examining the supremacy and effect of the more wide-ranging legislation coming from the EU, and considers the new EU framework Directive on nuclear safety, which had a 1 January 2004 implementation deadline but which is now expected during 2004.
EDTA (ethylene diamine tetra-acetic acid)-based chemical formulations are often employed for the decontamination of nuclear reactor coolant systems. However, its use in the dilute chemical decontamination (DCD) process operated in regenerative mode indicated several drawbacks. Hence, the search for a better decontaminant was imperative. Some of the potential amino carboxylic acids were explored for their suitability as a decontamination formulation constituent. NTA (nitrilo tri-acetic acid) was found to be a better substitute for EDTA with respect to properties that are relevant to DCD such as interaction of decontaminants and their metal complexes with ion exchange resins, oxide dissolution, corrosion compatibility of structural materials, and radiation stability. The studies revealed that better decontamination factors would be obtained if NTA-based formulations were used for the decontamination process.
The principle of best practicable environmental option (BPEO) has its roots in the 1975 recommendations made by the Royal Commission on Environmental Pollution, a new approach to pollution control. Since then BPEO has had a bumpy ride, failing to be clearly defined in law and applied equally and logically 'across the board'. This paper discusses the various issues surrounding BPEO, with particular emphasis on the nuclear industry, and suggesting ways forward for the future.
Although the Government's Energy White Paper of February 2003 intended to set objectives and policy direction for the next two decades and beyond, including cutting CO2 emissions by 60% by 2050, it vas decidedly non-committal on the future for nuclear power. This paper looks at the risks of the Energy White Paper strategy, particularly with regard to keeping the nuclear option open.
