Nuclear Energy: Promise or Peril?

Concluding Impressions

by C.R. Hill, A. Mechelynck, G. Ripka and B.C.C. van der Zwaan

THIS book has been prepared within the framework of a workshop organised by the Pugwash Conferences for Science and World Affairs. It is however the clear policy of Pugwash that any documented outcome of one of its workshops is the sole responsibility of the participants. In the course of this particular workshop meeting the various authors and other participants specifically decided not to draw up a formal set of overall conclusions. There seem, nonetheless, to be a number of threads that can usefully be drawn together from the various chapters in the book, and from the critical discussions that were held on them. The following attempt to do this is thus purely the responsibility of the editors and does not carry any endorsement either by Pugwash or by the other workshop participants.

Global Energy Management

MAJOR problems in energy management will occur in the coming century, and these now need to be addressed urgently. The combination of projected population increase and raising of GDP expectations, particularly in developing countries, suggests a factor of about 5 increase in global energy demand by 2100. Improved energy efficiencies can and must be achieved but are unlikely to diminish substantially the above prediction. Satisfaction of this increased demand for energy will call for increased use of some or all of. fossil carbon fuel, nuclear energy, and "renewables".

Fossil fuel at present supplies some 80 % of world energy needs. It generates substantial CO, particulate and other environmental pollution, particularly in countries where the "poverty trap" mitigates against clean and efficient technique. Fossil carbon is a finite resource: oil and gas will become scarce in the coming century; coal will last somewhat longer. The evidence for global warming, attributable substantially to manmade CO2 emissions, is compelling. The exact consequences of such global warming are unknown. They may comprise a combination of detriment and some eventual benefit. There must, however, be a serious likelihood of substantial human suffering, environmental damage, and sources of conflict.

Renewables that may make a substantial, non-greenhouse, contribution include: hydro, wind power and solar energy (both through direct heating and via photo-electric conversion). Reliable assessment of the full potential of most of these renewables, or of the use of "decarbonised" fossil fuels, will require substantially increased investment in research, development and pilot trials. At present however, it is very doubtful whether, in any combination, they have the potential to provide the bulk of projected 2100 world energy requirements. Thus, in their forward planning, it is unrealistic to expect governments to place total reliance on such resources.

Nuclear fusion could, eventually, prove to be an economically and environmentally acceptable means for providing a substantial, or even predominant, fraction of world energy needs. It may, however, be at least several more decades before we know whether its implementation is technically and economically practicable. In 1995, nuclear fission provided 18 % of the world's electrical power (7.3 % of total energy). The geo-political variation of that provision is considerable: from some 80 % in France, through 15-50 % in the majority of other industrialised countries, to zero in many of the poorer or smaller developing countries.

Objective comparison of the costs of nuclear- and fossil-generated electricity is difficult, particularly when taking into account the real environmental costs (including decommissioning) of both technologies. Undoubtedly, much of the pseudo-commercial viability of nuclear electricity in its early days was artificially supported by being able to write off much of the development costs against weapons budgets. Against this, however, there are now several examples of industrial economies (again, in particular France) that appear to operate very successfully whilst relying heavily on nuclear power.

Commercial interests have played a major part in the development of nuclear energy, although not always for the best. In the UK, for example, commercial forces have driven the momentum for reprocessing far beyond its overall economic (let alone security) justification. Conversely, enlightened public-sector leadership of the reactor programme in France appears to have resulted in economies of scale that have not been matched in countries where, as in the US, the open commercial market has had free rein.

There may be a strong case for well-controlled commercial and/or World Bank investment, in developing countries, in projects designed to enhance energy efficiency. A characteristic of many developing countries is the relative fragility of their electrical power distribution systems. This, often taken together with a shortage of suitable manpower and access to affordable capital, can present major problems in the introduction of nuclear electricity. Nonetheless, a number of such countries (particularly those that are oil-poor and thus wish to reduce reliance on external fuel supplies, such as China, India and Pakistan) have already established substantial, and largely home-grown nuclear power programmes.

Thus, whilst major questions exist over nuclear energy, it has become well established world- wide, in some cases apparently to the point of being indispensable, as one component of energy supply, at least during the next few decades. There are powerful arguments for increased development and trials of renewables, but unless and until such sources have been shown to be capable adequately to provide for world energy needs in the coming century, it will not be possible to rule out the necessity to continue and expand the nuclear contribution.

Health and the Environment

THE normal process of the generation of electricity from nuclear fission (in common with that from fossil fuel burning) results in the release of pollutants into the environment. The nature of nuclear (radioactive) pollutants is that they are expected to add to the existing natural incidence of cancer induction and genetic change in humans and other species. The extent of release of such pollution (both absolutely and per unit of generated electricity) has been reduced substantially in the past 10 years by improvements in technology, but may never be eliminated altogether.

In terms of biologically damaging doses to the typical human being, current nuclear electricity generation is expected (on the basis of United Nations' figures) to add some 0.01 % to the effect of existing, naturally occurring, radiation. At a conservative estimate, this translates to an expectation of some 100 additional cancer deaths annually, world-wide, over and above the approximately two million that are believed to be attributable to natural radiation.

In many countries it has not been possible to establish a settled, long term policy for managing the radioactive waste materials that result from reactor operations. Current practice, therefore, is to place materials in essentially temporary, shallow storage. Escapes of such material have occurred, either through bad management or resulting from unforeseen accidents. Among long- term options for disposal of high level wastes, geologically deep storage is generally favoured. There is increasingly good evidence that this could be implemented without consequences that would significantly add at any stage to human exposure to damaging natural radiation. On this topic, however, there exists a strong and understandable "Not In My Back Yard" syndrome, which has had effective political outcome in blocking implementation.

Nuclear power operations may also pollute the environment through major accidents, as was vividly illustrated by the Chernobyl accident, which was much the most damaging reactor accident to have ever occurred. An immediate human consequence of the Chernobyl accident was the 31 acute radiation deaths of operating and safety personnel in the month following the accident. In addition, the WHO and OECD currently predict as a consequence of the accident an 0.01 % lifetime increase in cancer incidence averaged over the European population (but predominantly in individuals who were immediately downwind at the time of the accident), implying an excess premature mortality of the order of 7000. Furthermore, there might be a similar number of adverse genetic changes affecting future generations. Additionally, there were major non-radiation effects: psychological, social and economic trauma, throughout a large population.

The main causes of the Chernobyl accident appear to have been serious human failure and unsafe design. The unit involved, a RBMK graphite moderated, water cooled reactor, was of a design that originated in the Soviet Union and is recognised as lacking safety features that are now standard elsewhere, where water-cooled, water moderated designs are now almost universal. It is noteworthy that there is now some 9000 reactor years experience of running such water reactors, in which there has only been one substantial accident: that at Three Mile Island, as a consequence of which there was no recorded or predictable human injury. Reactor safety remains a major cause for concern, however, and various proposals have been made in the direction of decreasing (albeit at some cost) risks and consequences of accidents below those inherent in current practice.

Whatever the validity of the above statements, and in whatever perspective they are viewed, there is a strong perception, among substantial groups in many countries, that the health and environmental risks posed by nuclear power are absolutely unacceptable. This perception is not universal, and seems to be largely characteristic of relatively prosperous, industrialised societies. In any case, from the point of view of optimal global energymanagement, it will be important to assess whether this perception is based on objective evidence and logical analysis.

Nuclear Weapons Proliferation

FOR many people, the gravest concern over nuclear energy arises from its incidental generation of weapons-usable fissile material. In many situations, production of highly enriched uranium (HEU) may be the most practical route for illicitly acquiring weapons usable fissile material. However, much current concern is focused on production of Pu in uranium burning reactors. Furthermore, thorium burning reactors, that would produce fissile U, are under design in some countries.

For Pu there are conflicting arguments as to whether security is maximised, on the one hand, by storing it as a constituent of spent fuel or, on the other, by extracting it from waste (reprocessing), followed by burning it as a mixed Pu/U oxides fuel ("MOX"). The reprocessed Pu from normal power reactor operation, although sub-optimal for weapons use, is nonetheless considered to be weapons-usable. World-wide, there are stocks of some 525 tons of plutonium (as metal or oxide) that have arisen either from power reactors or weapons decommissioning. This is being added to by continuing reprocessing of spent fuel. There are thus serious concerns for maintaining security of these stocks and for finding means (e.g. by burning as MOX or by mixing with stored spent fuel) for reducing and ultimately eliminating them.

Amongst technologies that could have the potential to reduce plutonium stocks is the fast- neutron reactor, that can be operated as an energy-generating plutonium burner. Developments here, however, have largely been discontinued, primarily on grounds of forecast economic viability. Another such technology that is being explored is the hybrid "proton accelerator driven reactor. This would operate sub-critically (thus supposedly being inherently rather safe) and would function both as a power generator and incinerator of plutonium and other actinides. Its feasibility and economics are yet to be demonstrated.

A substantial system of international and regional safeguard mechanisms has been established in an attempt to contain the problem of misuse of fissile materials. This appears to be largely effective, but it still contains two gaps: the five "original" nuclear weapon countries, that are only partly covered; and several nominally non-nuclear weapon countries, some of whom may be conducting undeclared activities that are in breach of the NPT. On the grounds that the nuclear weapon powers already have more plutonium and HEU than they know what to do with, it is particularly to these latter undeclared activities that further safeguarding needs to be directed.