Technical and economic indices of nuclear power plants and safety

Abstract

The technical and economic indices of nuclear power plants are determined independently of the safety indices. In the development of the reactor units of a nuclear power plant, the safety indices are introduced as constraints in accordance with the standards documentation (OPB-88, PBYA RU AS-89), and the cost factors are minimized according to the results of technical and economic calculations. It is these calculations that largely determine the choice of one or another variant of a nuclear power plant. This approach does not stimulate the development of reactor units of nuclear power plants with higher safety indices as compared to the indices required by the standards documentation. For example, if a nuclear power plant is proposed with safety indices 10 or 100 times better than the standard indices, but with technical and economic characteristics that are 10-20% worse than an alternative nuclear power plant whose safety indices fall at the limit of the standards requirements, then such a design could be rejected as being economically uncompetitive. At the same time, the future large-scale nuclear power plants will have to meet more stringent safety requirements [1]. This trend can be taken into account by developing mandatory standards for the future (for example, OPB-2010 and OPB-2030) that would direct the developers of the new-generation of nuclear power plants to increasingly more stringent safety requirements. As before, however, reactor installations with higher safety indices than the standards require could be rejected, even at the new, higher level of safety, if the technical and economic characteristics of the plants are somewhat worse. This situation can be avoided if the safety indices of the nuclear power plants being designed are taken into account in the calculation of the cost of the energy generated so that the nuclear power plant with the higher safety indices would remain competitive. This can be done, for example, by performing yearly calculations, for payments into a special insurance fund to compensate for losses resulting from an accident, replacement of capacity loss prematurely, and so on, for the capital component of the cost of energy. Such calculations must be all the greater, the lower the safety indices of a nuclear power plant, i.e. the probability that radioactivity (taking into account radiotoxicity) escapes into the environment is higher than the standard value for given initial events. This is not a new approach. It has been proposed previously, but for different reasons it has still not been acknowledged and is not used in practice. One possible criticism of this method for calculating the cost of energy is that the final cost of the energy is higher and the nuclear power plant becomes less competitive than a thermal energy plant. To counter this criticism, this method of calculation of the cost of energy can be used, for example, only when comparing different designs of nuclear power plants and in choosing one of them. It is also possible to redistribute between different items the contribution of the capital costs to the cost of the energy produced, including in it special insurance payments (a change in the discontinuation factor, norms for amortization deductions, and so on). This must be specially studied. Another objection could be the significant increase in the capital expenditures for equipment at a nuclear power plant with a strong relationship (a weak one will not stimulate higher safety) between the safety indicators and the size of the insurance payments. However, a large increase in the capital expenditures associated with high safety indices will occur only if safety is achieved by the traditional methods increase in the number and efficiency of different safety systems, intensification of and increase in the number of protective barriers, and others. However, if reactors with high passive safety, where the laws of nature absolutely exclude the most serious accidents [1, 2], such as can give rise to a dangerous emission of radioactivity, are considered for the nuclear power plants for the next century, then there should be no large increase of the capital expenditures for their construction.