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Results of an International Study on a High-Volume Plasma-Based Neutron Source for Fusion Blanket Development

Mohamed A. Abdou, Sam E. Berk, Alice Ying, Y. K. Martin Peng, Shahram Sharafat, John D. Galambos, Glenn W. Hollenberg, Siegfried Malang, Eric Proust, Steven J. Booth, Luciano Giancarli, Patrick Lorenzetto, Yasushi Seki, V. V. Filatov, Guelli Shatalov, Alexander Sidorenkov

Fusion Science and Technology

Volume 29 / Number 1 / January 1996 / Pages 1-57


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An international study conducted by technical experts from Europe, Japan, Russia, and the United States has evaluated the technical issues and the required testing facilities for the development of fusion blanket/first-wall systems and has found that some of the key requirements for the engineering feasibility of blanket concepts cannot be established prior to extensive testing in the fusion environment. However, because of availability and low cost, testing in nonfusion facilities (e.g., fission reactors and laboratory experiments) serves a critical role in blanket research and development (R&D) and reduces the risks and costs of the more complex and expensive fusion experiments. A comprehensive analysis shows that the fusion testing requirements for meeting the goal of demonstrating a blanket system availability in DEMO > 50% are as follows: a 1 to 2 MW/m2 neutron wall load, a steady-state plasma operation, a > 10-m2 test area, and a fluence of > 6 MW·yr/m2. This testing fluence includes 1 to 3 MW·yr/m2 for concept performance verification and >4 to 6 MW·yr/m2 for component engineering development and reliability growth/demonstration. Reliability and availability analyses reveal critical concerns that need to be addressed in fusion power development. For a DEMO reactor availability goal of 50%, the blanket availability needs to be ∼80%. For a mean time to recover from a failure of ∼3 months, the mean time between failure (MTBF) for the entire blanket must be >1 yr. For a blanket that has 80 modules, the corresponding MTBF per module is 80 yr. These are very ambitious goals that require an aggressive fusion technology development program. A number of scenarios for fusion facilities were evaluated using a cost/benefit/risk analysis approach. Blanket tests in the International Thermonuclear Experimental Reactor (ITER) alone with a fluence of 1 MW·yr/m2 can address most of the needs for concept verification, but it cannot adequately address the blanket component reliability growth/demonstration testing requirements. An effective path to fusion DEMO is suggested. It involves two parallel facilities: (a) ITER to provide data on plasma performance, plasma support technology, and system integration and (b) a high-volume plasma-based neutron source (HVPNS) dedicated to testing, developing, and qualifying fusion nuclear components and material combinations for DEMO. For HVPNS to be attractive and cost effective, its capital cost must be significantly lower than ITER, and it should have low fusion power (∼150 MW). Exploratory studies indicate the presence of a design window with a highly driven plasma. A testing and development strategy that includes HVPNS would decisively reduce the high risk of initial DEMO operation with a poor blanket system availability and would make it possible — if operated parallel to the ITER basic performance phase — to meet the goal of DEMO operation by the year 2025. Such a scenario with HVPNS parallel to ITER provides substantial savings in the overall R&D cost toward DEMO compared with an ITER-alone strategy. The near-term cost burden is negligible in the context of an international fusion program with HVPNS and ITER sited in two different countries.

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