The history and the prospects of japanese nuclear power development program

FBRs are regarded as the most probable option among non-fossil energy resources which will underpin the future energy demand in Japan, considering the effective uranium utilization and the need to lower the burden on the natural environment. However, it will take a long time to utilize FBRs due to a number of pending technical issues and improvements of cost efficiency. For the time being, therefore, light water reactors will continue to play a dominant role in power generation: thus, it is urgently necessary to establish the quasi-domestic nuclear fuel cycle for them, especially in the field of enrichment and spent fuel reprocessing — a goal of the Japanese nuclear policy since the dawn. Furthermore, public acceptance is significant factor which must be considered. This can best be achieved by more safety performance of light water reactors and through publication of extensive information, including decisions by the industry and government.     

Safeguard management for operation security in nuclear power plants (NPPs)

Safeguard modeling is conducted for the successful operations in the nuclear power plants (NPPs). The characteristics of the secure operation in NPPs are investigated using the network effect method which is quantified by the Monte-Carlo algorithm. Fundamentally, it is impossible to predict the exact time of a terror incident. So, the random sampling for the event frequency is a reasonable method, including the characteristics of network effect method such as the zero-sum quantification. The performance of operation with safeguard is the major concern of this study. There are three kinds of considerations as the neutronics, thermo-hydraulics, and safeguard properties which are organized as an aspect of safeguard considerations. The result, therefore, can give the stability of the operations when the power is decided. The maximum value of secure operation is 12.0 in the third month and the minimum value is 1.0 in the 18th and 54th months, in a 10 years period. Thus, the stability of the secure power operation increases 12 times higher than the lowest value according to this study. This means that the secure operation is changeable in the designed NPPs and the dynamical situation of the secure operation can be shown to the operator.     

Management of radioactive wastes from the operation of nuclear power plants

A prerequisite for the acceptance of the nuclear energy system is the effective management of the rad-wastes. Among the wastes to be considered, there are the wastes from the operation and decommissioning of nuclear power plants, as well as those from the nuclear fuel cycle. For the management of operating wastes, processes and facilities optimized in the course of several decades, are available, with which the raw solid and liquid wastes can be reduced in volume and turned into products which are physically and chemically stable and thus suitable for final disposal. The management of spent fuel can be done either by direct final disposal or reprocessing. The required interim storage facilities are ready for operation. The methods and a facility for packaging spent fuel for direct final disposal are in an advanced stage of development and construction. If fuel assemblies are to be reprocessed abroad, the wastes generated from the process must be taken back. Decommissioning wastes have technical properties which correspond essentially to the various groups of operating wastes and can thus be processed with similar methods; however since large quantities of them are generated in relatively short times, they present particular logistic problems. All waste types end up in final disposal sites to be built under the responsibility of the federal government. A final disposal site for low level wastes is in operation. In addition, two final disposal projects for accommodating higher level wastes including spent fuel for direct disposal and vitrified wastes from reprocessing, are being pursued.     

A neural network based operation guidance system for procedure presentation and operation validation in nuclear power plants

An operation guidance system (OGS) was developed to regulate and supervise operators’ actions during abnormal environments in nuclear power plants (NPPs). The system integrated a primitive computerized procedures system (CPS) and an operation validation system (OVS) imbedded in a virtual simulated operational environment. As the key component of the OGS, OVS provided two important functions for the operators: validated check of operations, and qualitative and quantitative effects analysis of operations. Each of operators’ action was evaluated by the system and possible results were simulated by using artificial neural networks (ANN). Finally, corresponding suggestion or warning was provided to operators. This should reduce human errors during operation in emergency scenarios.     

Status and further development of nuclear power plants with WWER in Russia

Nuclear electricity production in some European countries is based partially or wholly on NPPs with water-cooled water-moderated power reactors (WWERs) of Soviet design. Although only about a quarter of all the WWER units are in operation now in Russia, the country remains responsible, to a certain degree, for supporting the vitality of this well-proven line and its further development. Research work is consecutively carried out and measures are taken in the WWER-based NPPs to improve their safety and cost-effectiveness indices. Nearly constructed WWER-1000/320 units are expected to be commissioned in the Kalinin and Rostov NPPs in the coming years. A new generation of NPPs extensively using passive safety systems are at the final stage of development and are due to be started up after the year 2000.     

Flood hazards for nuclear power plants

Flooding hazards for nuclear power plants may be caused by various external geophysical events. In this paper the hydrologic hazards from flash floods, river floods and heavy rain at the plant site are considered. Depending on the mode of analysis, two types of hazard evaluation are identified: (a) design hazard which is the probability of flooding over an expected service period, and (b) operational hazard which deals with real-time forecasting of the probability of flooding of an incoming event. Hazard evaluation techniques using flood frequency analysis can only be used for type (a) design hazard. Evaluation techniques using rainfall-runoff simulation or multi-station correlation can be used for both types of hazard prediction.     

Welding consumables for nuclear power plants

In nuclear power plants, submerged arc welding and covered arc welding have long been employed especially for main weld seams, including the core region of RPV.This paper investigates the mechanical properties of several welding consumables we have developed for industrial plants — that is, welding consumables which lower the phosphorus and copper content of the welded metal, those for plates possessing particularly high tensile strength and those for the narrow gap welding method.Recent data derived from irradiation embrittlement tests show that these welded metals using a non-copper coating are highly effective in minimizing shifts in the transition curve.Welding consumables for A533B C1.2, A543 C1.1 or A508 C1.4 steels have a higher tensile strength than those for A533B C1.1 or A508 C1.3.We have developed submerged arc and covered arc welding consumables to be used with these kinds of steels, and it was confirmed that these consumables possess excellent tensile strength and notch toughness.Our tests also confirmed that the narrow gap SAW and MIG welds are more efficient than the conventional ones. Moreover, the mechanical properties of the welded metals are also excellent.     

Securing safe operation of VVÉR reactor systems in nuclear power plants

The safe operation of VVéR reactors has been discussed throughout the entire design process, taking account of the normative documentation, including the international requirements (IAEA, EUR). After the first domestic normative document “Basic principles for securing the safety of nuclear power plants” was approved in 1973, work began on the reconstruction of the first-generation VVéR-440 power-generating units. The measures taken to increase safety concerned all types of reactors VVéR-440 and-1000. Information on implementing these measures is presented. __________ Translated from Atomnaya énergiya, Vol. 101, No. 2, pp. 87–93, August, 2006.     

Economic aspects of the development of nuclear power and fuel cycle plants in the USSR

Conclusion Plutonium breeding in fast reactors themselves will not have any significant effect in the next 20–25 years on growth rate of the capacity of nuclear power stations with fast reactors.The character of the distribution of the capital expenditures on nuclear power stations and on the fuel cycle shows that the bulk of the expenditures is spent on the construction of the nuclear power stations and only 20% on the development of the fuel-cycle plants. For this reason, greatest savings of capital expenditure are given by a reduction in the construction costs of nuclear power stations by means of improvements in the design and of the reactor and the thermal and mechanical equipment of the plant.In the fuel cycle the biggest economic effect is produced by measures that lead to a reduction in the specific consumption of natural uranium since the capital expenditure on the mining operations constitutes about one-half of the total capital expenditures on the fuel cycle. The natural uranium costs also make up roughly one-half of the fuel component of the cost of electricity generated by a nuclear power station. As the price of uranium rises, this fraction of costs will also increase.Translated from Atomnaya Énergiya, Vol. 43, No. 5, pp. 365–369, November, 1977.     

From VVÉR-210 to VVÉR-2000: Experience in the development and improvement of reactor designs for nuclear power plants

Special Design Office “Gidropress.” Translated from Atomnaya énergiya, Vol. 76, No. 4, pp. 310–318, April, 1994.     

The role of probabilistic methods in the development of regulations for nuclear power plant design-assessment and projections in France

The discussion of this panel session deals with the use of probabilistic methods in safety analysis and safety regulations. The author presents her opinion on the status of reliability methods for systems evaluation and on the event tree methodology. The difficulties encountered in the use of these techniques are shown. They explain the slow introduction of the latter in the safety authorization process. The future of the development of probability techniques for use in French regulation are described at the end of the paper.     

Regulatory practices for nuclear power plants in India

Atomic Energy Regulatory Board (AERB) is the national authority to ensure that the use of ionizing radiation and nuclear energy in India does not cause undue risk to the health of workers and members of the public, and the environment. AERB fulfills its mission by stipulating and enforcing rules and regulations concerned with nuclear and radiological safety. This paper describes the regulatory authorization process of AERB as applicable to nuclear power plants (NPPs) during their construction as well as operating phases. The safety review process during construction is presented as case studies. Some current issues related to operating plants are also described. Two typical examples of safety upgradations made in old generation nuclear plants are given.The regulatory process in India is continuously evolving to cater to the new developments. Some of the recent initiatives taken by AERB in that direction are briefly described. Today AERB faces new challenges like simultaneous review of a large number of new projects of diverse designs, a fast growing nuclear power program and functioning of operating plants in a competitive environment. This paper delineates how AERB is gearing up itself to meet these challenges in an effective manner.