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Pastimes : Triffin's Market Diary -- Ignore unavailable to you. Want to Upgrade?

To: Triffin who wrote (165)	6/2/2001 11:06:32 AM
From: Triffin	Read Replies (1) \| Respond to of 868

BC: PEBBLE BED By John C. Zink, Ph.D., P.E., Contributing Editor The California energy crisis may have breathed new life into the U.S. nuclear power business. Even the popular press is recognizing nuclear energy as a serious choice for addressing the nation's expanding electricity needs. In response, energy policy makers mapped out a strategy for taking advantage of this opportunity. But just when industry leaders agreed on a plan for updating U.S nuclear technology, an outsider, South Africa's pebble bed reactor, intruded on their orderly process. Last year's Department of Energy (DOE) workshop of nuclear experts produced a plan to develop Generation IV nuclear power plant technology, with enhanced safety and economics, based on the many successes of the Generation I - III Light Water Reactors (LWRs). In early March senators Domenici and Craig introduced The Nuclear Energy Electricity Assurance Act of 2001, which authorizes DOE to increase spending on nuclear energy initiatives by $275 million. One of the most important of these initiatives is $50 million for work on the Generation IV LWR as proposed at the DOE workshop. While many feel this is a good start toward rejuvenating nuclear power in the U.S., there is another school of thought. Some industry insiders are convinced that the public will readily accept new nuclear plants only if these plants are radically different from past designs. While this group may be comfortable with the expected safety and economic performance of the proposed Generation IV plants, they feel the public will not share their confidence. Some of these nuclear industry heavyweights are backing the pebble bed reactor concept as an alternative to the DOE funded Generation IV design. I wrote about the pebble bed reactor's history and the concept's revival in a 1998 Power Engineering column. At that time Eskom, the big South African utility, had just announced a significant investment in developing this design, with a goal of having a pilot plant online by 2003. The Eskom plan calls for a 100 MW reactor module using helium coolant, which would also be the working fluid for a gas turbine (Brayton cycle) generator. Now, Exelon Corp., a major operator of nuclear power plants in the U.S., has bought a 12.5 percent interest in the South African project. Exelon is participating in a detailed feasibility study due for completion in June. Exelon will then decide whether or not to proceed with initial licensing activities leading to potential future construction of a pebble bed reactor plant in this country. On January 31 Exelon briefed the Nuclear Regulatory Commission (NRC) staff on the company's plans and discussed the process the NRC might require in order to license such a plant for operation in the U.S. At least one NRC staff member has suggested that the Commission should wait until the first pebble bed plant has been built in South Africa, now expected to be in 2005, before approving the design for use here. One of the big reasons many feel the pebble bed reactor will achieve better public acceptance is that it relies on its inherent physical processes for most of its safety features. Instead of being fueled with long tubes of uranium cooled by flowing water, the pebble bed reactor would have baseball-size fuel pellets of uranium and graphite cooled by helium gas. This configuration has the advantage that, even if the gaseous coolant stopped flowing entirely, the fuel pebbles would not get hotter than about 2,900 F, or about 650 F below the temperature at which fuel damage would begin to occur. This eliminates the possibility of fuel melting, the most serious accident one can contemplate for a nuclear reactor, and the accident that provides the most horror scenarios for the anti-nukes to use in attacking the technology. (Who can forget "The China Syndrome," Hollywood's contribution to public understanding of nuclear reactor safety?) Eskom believes the pebble bed concept also has economic advantages. Because it lacks water coolant that could flash to steam with the attendant pressure surge inside the reactor, and because of the fuel's hardiness, a pebble bed plant should not require many of the expensive add-on safety features required of current LWRs. Its online refueling feature eliminates the need for periodic plant shutdowns for refueling, with the resulting loss of production, and allows for efficient use of the uranium fuel. Pebble bed plants should also require shorter construction times, which means lower interest expense during construction. Properly done, the Generation IV plant should have the same favorable safety characteristics as the pebble bed reactor. According to the schedules for the two prototype plants, however, the pebble bed will have about a 15-year head start. It is refreshing to once again see enough interest in nuclear technology that there is real competition between different reactor types. It is even more encouraging to see both governments and private industry willing to spend substantial sums on a nuclear future