October 1990

Kent F. Hansen, Massachusetts Institute of Technology (Panel Chair)

Wallace B. Behnke, Commonwealth Edison (retired)

Sheldon B. Cousin, Stone & Webster Engineering Corporation

Ersel A. Evans, Battelle Pacific Northwest Laboratory

Donald R. Olander, University of California at Berkeley

Victor H. Ransom, Purdue University

James D. White, Oak Ridge National Laboratory


The JTEC panel on nuclear power in Japan examined the status and direction of nuclear power-related research and development in Japan in six areas: the nuclear fuel cycle, nuclear materials, instrumentation and control technology, CAD/CAM, nuclear safety research, and nuclear plant construction. The panel based its report on a review of literature and a one-week trip to Japan in January 1990 during which panel members visited numerous Japanese laboratories and other nuclear facilities. The panel found that the nuclear power industry in Japan was at an advanced state of development; Japan had become technologically self-sufficient. Long-term goals of the Japanese program included closure of the complete fuel cycle and pursuit of the liquid metal fast breeder reactor as the future base system.

The Context of Nuclear Power in Japan

The panel found the Japanese program of nuclear power research and development to be blessed with many benefits, including a strong, consistent federal commitment to nuclear power; an adequate supply of R&D funds; a stable set of priorities for R&D; a well-developed distribution of responsibilities between the public and private sectors; and a highly capable group of agencies engaged in R&D. In 1955, Japanese policymakers, recognizing that their nation lacked indigenous energy sources, made a commitment to develop nuclear power as the most likely vehicle for achieving a self-reliant electric energy supply system. This key decision has remained a cornerstone of Japanese energy policy.

The structure in which the nuclear program evolved included a well-developed long-range plan, a clear distribution of obligations among plan participants, a strong utility industry capable of constructing and operating plants and learning from its experiences, a strong supply sector capable of designing plants and developing the designs toward the ultimate goal, and a commitment to adequate funding for nuclear R&D to ensure the quality and completeness of the effort. Other factors became important, but none were displaced or downgraded. Public opinion grew negative toward nuclear power, particularly after Chernobyl. Safety grew increasingly important in Japan. The industry devoted considerable resources to ensuring safe operations and conducting safety research. But this added emphasis came as an addition to ongoing efforts, not as a replacement.

The Research and Development Focus

The Japanese nuclear research program is dominated by light-water reactor (LWR) technology, the nuclear fuel cycle, and advanced reactors. These three areas consumed about $1.5 billion in 1989 R&D funds. LWR technology is supported mainly by the electric utilities and the vendors. Research focuses on improvements in plant safety and in economics. They are working to develop improved, extended burnup fuels for nuclear power plants. Another important area is controls and instrumentation, including advanced control room design. Longer-range research focuses on developing advanced LWRs of both the boiling water reactor (BWR) and pressurized water reactor types.

Closure of the nuclear fuel cycle is a priority for the Japanese. They do not wish to rely on external suppliers for enrichment services or reprocessing services. This R&D is being done primarily at government research laboratories. Government expenditures on the fuel cycle were $280 million in 1989, and the utility contribution was $200 million. The largest expenditure, about $180 million, was for reprocessing. The Japanese, foreseeing a need for plutonium in their future breeder economy, are committed to having all of the reprocessing technology developed and in place in advance of the widespread deployment of fast breeder reactors (FBRs). The long-term goal of the fuel cycle research is complete self-sufficiency, with the ability to handle enrichment, fuel fabrication, reprocessing, and waste storage; the near-term goal is to require only uranium ore and to be self-sufficient in all other aspects of the cycle.

The largest nuclear R&D expenditures are for the advanced reactor program, which accounted for $775 million in 1989. The FBR received $650 million, or nearly 85 percent of the total advanced reactor budget. The key project is the Monju reactor. Similar in design to the Clinch River Breeder, the Monju reactor is a 280 MWe liquid metal fast breeder reactor. At the time of the panel visit, construction was about 80 percent complete, with initial criticality scheduled for 1992.


Nuclear Fuel Cycle

Japan is committed to the complete fuel cycle -- uranium mining, conversion, enrichment, irradiation, reprocessing, and waste disposal. Unlike the U.S., Japan includes plutonium utilization and uranium recycling in its nuclear program as a matter of national policy. As part of the effort to develop a complete fuel cycle, the Japanese participate aggressively in international cooperative efforts. Such efforts encompass university and national laboratory programs and cooperation with government and industry organizations worldwide to achieve the best engineering and most effective commercialization for all parts of the fuel cycle.

Nuclear Materials

Japanese materials research began from a base that incorporated much initial U.S. research. Japan's LWR plants have higher energy availability than U.S. plants for several reasons, including improved materials. Because of their careful control of water chemistry and materials selection, the Japanese have had very few problems with Intergranular Stress Corrosion Cracking in their BWRs or steam generator problems in their PWRs. The Japanese are conducting research on extended-life fuels for both the BWRs and PWRs with the objective of extending the operating cycle to eighteen months without suffering fuel failures. Meeting this goal would increase plant availabilities to over 80 percent. The Japanese also have demonstrated interest in load following, and considerable effort is underway to develop and test long-lived fuel that could be cycled in power. Advanced reactor materials research is primarily directed toward breeder fuels and work related to U-Pu fuels for use in LWRs. A small amount of research is being done on high-temperature, gas-cooled reactor fuels.

Instrumentation and Controls

Application of improved instrumentation and controls (I&C) to nuclear power plants appears to be much farther along in Japan than in the U.S. The panel attributed this progress to Japan's long, productive R&D commitment and its healthy industry. The Japanese have demonstrated particular interest in several specific technologies. National labs, vendors, and universities have vigorously pursued work in artificial intelligence and expert systems, with applications in component diagnostics and operator support systems. Fiber optics are being used in some existing plants and will be used in new plants. The subject of man-machine interfaces was receiving a great deal of attention in Japan. Research was focusing on clarification of human behavioral characteristics, systematic applications of behavioral information, and organizational and systems aspects of human error experience.

The panel found no evidence that Japan was ahead of the U.S. in basic research. Indeed, the U.S. retains a lead in several areas, including information theory and advanced computer languages.

CAD/CAM Technology

CAD/CAM technology has reached comparable levels of development in Japan and the United States. Both nations are using CAD/CAM to develop three-dimensional models of conceptual designs of new plants. Common databases are being used by different designers for technical areas such as reactor physics, thermal hydraulics, and piping. The Japanese nuclear power program provides the opportunity to incorporate application into the design and fabrication activities because real plants are being developed and built.

The Japanese are actively pursuing further development of CAD/CAM systems. Near-term goals include full 3-D design capability, common databases, and interactive communication with designers. Longer-term goals include detailed design, procurement documents, and manufacturing specifications. Databases would be generated for the as-built system for use during plant operation. The panel felt that the United States remained the leader in conceptualizing and developing software, CAD/CAM systems, database management programs, system integration, and nonnuclear-related applications. The tendency in Japan was to purchase completed packages and adapt them for use in specific applications.

Nuclear Safety

Concern about nuclear plant safety has permeated the design and operation of nuclear plants in both the U.S. and Japan. However, there are significant differences between the two nations in safety R&D. In Japan, safety is seen as a matter of such great importance that even minor events must be avoided. As a consequence, much safety R&D in Japan focuses on operational issues. In the U.S., the key element of safety research is severe accident scenarios.

Japan's government R&D is closely tied to support of regulatory activities. Large-scale test facilities are maintained for research in thermal hydraulics, two-phase flow, and seismic testing of components and systems. Results from the research are used to validate computer models of systems behavior. In general, the panel found the U.S. ahead of Japan in conceiving and developing such codes. However, the Japanese enhance the codes more completely, using experimental data for validation. The Japanese emphasize human factors in nuclear safety R&D. Vendors use research results to improve control room design and support systems evaluation. The Japanese have been slow to enter the field of probabilistic safety assessment because of the view that, since severe accidents will not occur at their plants, they have no need for Level 3 capability. Nevertheless, the issue was under active study at the time of the panel's visit. In Japan much applied AI work is conducted by federal labs, utilities, and vendors, though there is little coupling to academia.

Nuclear Power Plant Construction

Japan has been more successful than the U.S. in holding down the cost of constructing nuclear power plants. Institutional, regulatory, and cultural differences account for the higher cost of U.S. construction. Japan has also achieved effective nuclear regulation with far less disruption and delay in construction and licensing than has occurred in the United States. Japan's improvements in the construction process include (a) shop fabrication of very large modules that are shipped to the site and installed; (b) substantial completion of detailed engineering drawings before start of construction; (c) fully computerized, comprehensive construction sequence plans; and (d) comprehensive quality assurance programs with detailed inspection, but performed to minimize interference with construction. Japan was at an early stage in applying robotics to field construction at the time of the panel's visit.

Japan spends more on construction-related R&D than the U.S., and is more effective at transferring new technology into construction. Japan's nuclear industry is applying the latest design improvements and new technology from R&D to construction. The only opportunities for U.S. manufacturers and A/E firms to apply developments have been in overseas projects, such as those in Korea. Without new construction activity, the U.S. could lose parity with Japan in construction-related R&D and associated infrastructure. These trends could lead to higher electricity prices for U.S. consumers and an increased competitive disadvantage for U.S. manufacturers in global markets.

Published: March 1994; WTEC Hyper-Librarian