Hugh Richards reveals uneasiness inside the Assembly Government about the next generation of nuclear reactors
An unintended consequence of devolution is that Wales is finding itself at the centre of international questions about the long-term viability of radioactive waste. Questions being asked by the Welsh Assembly Government have uncovered disturbing and hitherto concealed facts about spent nuclear fuel from new nuclear reactors.
Starved of orders for decades, the nuclear industry is trying to compete in a liberalised electricity market by cutting costs, both in new designs and the operation of existing reactors. To boost the efficiency of their reactors, operators have progressively enriched the uranium they use as fuel to increase its ‘burn-up’ rate. This means that the fuel rods can be left in the reactor for longer, extracting more energy from each tonne and producing less waste per unit of electricity. Enthusiasm to allow ever greater ‘burn-up’ of fuel to assist reactor operators has until now masked growing concern about the resulting waste.
High burn-up spent fuel from the reactors proposed for sites such as Wylfa on Anglesey and Hinkley Point in the Severn Estuary will be twice as hot and twice as radioactive as the legacy spent fuel that the government wants to dispose of underground. Sites of new nuclear power stations will accumulate and store this hazardous material above ground over very long periods. The International Atomic Energy Agency knows that any benefits of lower electricity costs during the operation of reactors in this way will be offset by an increase in the cost of managing the spent fuel. The problem is that the costs will long outlast any benefits.
In March 2009 a meeting of experts, convened in Cardiff by Environment Minister Jane Davidson, heard that the very high burn-up spent fuel proposed for Britain cannot be put underground for a hundred years because it is too hot. The use of such fuel is in its infancy and there is no experience of its long-term management. Communities such as Ynys Mon where there is political clamouring for a new nuclear power station, could find that their ‘interim spent fuel stores’ become the ‘de facto’ nuclear waste dumps of the future. Coastal sites, particularly those on the Severn Estuary could face the daunting task of defending interim stores against centuries of rising sea levels.
For over thirty years radioactive waste has been identified as an issue that is central to the acceptability of nuclear power. Responding to a Royal Commission demand that a method be demonstrated for the safe containment of long-lived, highly radioactive waste for the indefinite future, the UK government pledged as far back as 1977 that it would “ensure that waste management problems are dealt with before any large nuclear programme is undertaken”.
Twenty-five years later in 2002 a UK government energy review confirmed that “the unsolved problem of long-term nuclear waste disposal” was the main focus of public concern about nuclear power. In 2002 the Welsh Assembly Government joined with the UK Government and the other devolved administrations to set up a programme to tackle the problem of Britain’s legacy waste. However, the Assembly does not accept that this sets a precedent for the disposal of waste from any new nuclear power stations. Last year, Wales’ Environment Minister Jane Davidson, started inquiring about the nature of new build waste.
The current UK government has decided to facilitate a new generation of nuclear reactors, pointing to progress that has been made in establishing the concept of a deep geological repository for our existing ‘legacy’ radioactive waste that could be extended to take the waste from new reactors. This ‘extendibility’ has now been thrown into doubt.
In January 2008 he Nuclear Industry Association said that such a repository could readily accommodate the “smaller volumes of easier-to-handle wastes from that new generation of nuclear plants.” However, the type of fuel that they intend to use brings uncertainties about its safety and the feasibility of its long-term storage and disposal.
In March 2007 the International Atomic Energy Agency reminded Britain that it must not go ahead with a new generation of nuclear power stations until it has a “clear and robust” plan in place for the waste. In particular, if the public is to be convinced, a credible and satisfactory answer to the management of spent fuel is required. We are witnessing a clash between the competitiveness of nuclear power and the long term safety of its spent fuel.
Chart 1 illustrates that the burn-up of nuclear fuel has doubled over the last thirty five years and is forecast to continue rising. Spent fuel to be discharged from the European Pressurised water Reactor at Olkiluoto in Finland, with a burn up of about 45,000 MegaWatt days per tonne of Uranium (MWd/tU), is at the limit of temperature output that can be disposed of in the Swedish repository adopted by our Nuclear Decommissioning Authority as a reference design for the disposal of Britain’s legacy waste.
Because the new nuclear fuel is left in the reactor for longer its cladding will become thinner, with higher gas pressure within the fuel elements, and this vulnerability will persist throughout its long term storage and disposal. Long-term dry storage of spent fuel above 45,000 MWd/tU is predicted to lead to the failure of fuel cladding. The International Atomic Energy Agency long ago acknowledged that there should be a plateau burn-up level in confrontation with regulatory constraints but they have yet to enforce one.
High burn-up spent fuel will emit ten times as many neutrons per second as legacy spent fuel requiring greater shielding. More demanding at every stage of the nuclear cycle, it will increase potential worker and public exposure to radiation. But it is the generation that has to retrieve the spent fuel from long term storage, condition it, encapsulate it and place it deep underground that will be most exposed to the health detriments.
The Department of Energy and Climate Change propose that the operators would, after a period of storage to allow the spent fuel to cool down and become less radioactive, encapsulate it in containers for disposal, and at that time the taxpayer would take title to and responsibility for the waste. Resources set aside during operation are to cover the costs. Should these evaporate, in some global economic break down, future generations may find themselves with the liabilities of nuclear waste management, but without the means to pay for them.
Although it is more hazardous to manage, insufficient information has been supplied to judge the long-term safety of high burn-up spent fuel, its containment design, or its ability to withstand aircraft attacks.
After 18 years in cooling ponds the spent fuel from Westinghouse reactors would be transferred to vertical dry casks with only their tops above ground, but these are only licensed for 20 years in the United States, and the effects of heat build up on the long term integrity of the fuel is unknown. AREVA, the French reactor company have designed dry casks but have decided to store their British EPR spent fuel in ponds until it can be conditioned. In France they are considering pond storage for up to 300 years for high burn-up spent fuel. The problem with ‘wet storage’ is that pumps have to be kept going continuously and safety could be compromised by a terrorist attack that partially or completely drains the spent fuel pool. This could lead to the rapid heat-up of spent fuel to temperatures at which the zirconium alloy cladding would catch fire and release radiation.
Chart 2 is based on official estimates of the amount of radioactivity that would be created by a 10GW new build nuclear programme, and stored on sites. There are no historical precedents for private corporations conditioning their hazardous wastes a century after the income stream has ceased.
Nuclear regulators have confirmed that they do not want to see wastes created that cannot be managed through to their final disposal. Yet the Department of Energy and Climate Change is reshaping nuclear regulation in order to speed it up. Under European law any decision that alters our exposure to radiation should do more good than harm. This principle is known as justification.
However, the danger of allowing a department promoting nuclear power to make regulatory decisions is that in ‘reducing regulatory risks for investors’ it will pre-empt proper consideration of health detriments and dilute the robust and effective regulation of nuclear hazards. A predictable outcome of presenting Britain as the best place in the world in which to invest in nuclear power is that untried, untested ideas are being pushed harder in Britain than elsewhere. In the face of new build nuclear reactors it is unsurprising that no community in Wales has ‘volunteered’ for a deep geological repository for our legacy waste.
The justification process for new nuclear reactors has come at a time when regulatory ‘confrontation’ is required. Waste management and disposal is an integral part of nuclear power generation so we have to consider all detriments, including that from the waste, before allowing any new nuclear programme. Jane Davidson is right to be concerned about the management and security of radioactive waste from new reactors and to support the call for a public inquiry into justification.
The minutes and background papers of the March 2009 meeting convened by Environment Minister Jane Davidson can be found here.