HTGR Knowledge Base

Conference Article: Achieving optimum graphite performance in AGR core and fuel

Norfolk, D.J.; Johnston, G.O.; Tucker, M.O. (Central Electricity Generating Board, Berkeley (UK). Berkeley Nuclear Labs.)

Abstract

The Central Electricity Generating Board has a total of five twin-reactor nuclear power stations on four sites using advanced gas-cooled reactors (AGR), of which the earliest was commissioned in 1976, and the last is expected to begin the commercial operation in the next year. All have graphite cores, and are cooled by CO2. So far, the core has not been replaced. If the performance of graphite deteriorates too rapidly, the life of reactors ends prematurely. In AGRs, a complex coolant flow path allows high power density and thermal efficiency, hence particularly favorable economical performance, combined with acceptably low core graphite temperature. The gas flow in a channel is separated with annular graphite sleeves, which also support a fuel pin, and are replaced with fuel every 5 - 7 years. This work falls n three main areas. The first is to develop the method of assessing and predicting the performance throughout component life. The second is to optimize operating conditions, particularly coolant composition, so as to delay deterioration. The third is to develop surveillance and monitoring method. This paper summarized the process affecting core and fuel graphite performance in the AGR environment, and describes progress in several key areas. Effect of radiation on graphite, consequence for moderator performance, development of AGR coolant composition, stress prediction and so on are reported.

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key words: agr type reactors; coolants; graphite; jackets; moderators; neutron beams; performance; physical radiation effects; reactor cores; reactor materials; reactor monitoring systems; reliability; sleeves; stress analysis; stresses; beams; carbon; enriched uranium reactors; gas cooled reactors; graphite moderated reactors; particle beams; radiation effects; reactor components
Reference:
Specialists' meeting on graphite component structural design, JAERI Tokai (Japan), September 8-11, 1986
International Atomic Energy Agency, Vienna (Austria). International Working Group on Gas-Cooled Reactors
IWGGCR--11, pp:176-181