HTGR Knowledge Base

Conference Article: Study on efficient methods for removal and treatment of graphite blocks in a gas cooled reactor

S. Fujii, M. Shirakawa, T. Murakami

Abstract

Abstract.Tokai Power Station (GCR, 166 MWe) started its commercial operation on July 1966 and ceased activities at the end of March 1998 after 32 years of operation. The decommissioning plans are being developed, to prepare for near future dismantling. In the study, the methods for removal of the graphite blocks of about 1,600 ton have been developed to carrying out it safely and in a short period of time, and the methods of treatment of graphite have also been developed. Technological items have been identified for which R&D work will be required for removal from the core and treatment for disposal.

  1. In order to reduce the programme required for the dismantling of reactor internals, an efficient method for removal of the graphite blocks is necessary. For this purpose the design of a dismantling machine has been investigated which can extract several blocks at a time. The conceptual design has being developed and the model has been manufactured and tested in a mock-up facility.
  2. In order to reduce disposal costs, it will be necessary to segment the graphite blocks, maximising the packing density available in the disposal containers. Some of the graphite blocks will be cut into pieces longitudinally by a remote machine. Relevant technical matters have been identified, such as graphite cutting methods, the nature of fine particles arising from the cutting operation, the treatment of fine particles for disposal, and the method of mortar filling inside the waste container.

view the full text of this article (9 pages, format: PDF, size= 808kB)

key words: Gas Cooled Reactor, Nuclear Technology
Reference:
IAEA Technical Committee Meeting on "Nuclear Graphite Waste Management", held from 18-20 October 1999 in Manchester, United Kingdom
International Atomic Energy Agency, Vienna (Austria)
TCM-Manchester99, pp:105-113