commercial nuclear power reactor stands in the plains beneath the Rockies at Fort St. Vrain, Colorado.
It is unique in that it runs on the thorium fuel cycle (breeding a uranium isotope that does not occur in nature). But what makes it America's finest is that it is a High Temperature Gas Reactor (HGTR), a reactor which is even safer than the other reactors in the US (Light Water Reactors
¾LWR's), and more efficient as well. The HGTR's potential goes beyond the generation of electricity.GRAPHIC: A01_8101.TIF
(Caption: The 330 MW Ft. St. Vrain HTGR. It would take about two million solar panels such as the one hauled in by antinuclear protestors (May 1979) to match its power.)
The safety of the HGTR is due to the fact that it uses a gas (helium) as a coolant, and graphite as a moderator, i.e., as the material that slows down the neutrons
¾unlike a LWR which uses water as both coolant and moderator. If the water leaks out from a LWR, the fuel rods will overheat, and their metal cladding may melt. The big hoax about TMI was "scientists told us it couldn't happen." In reality, they told anybody willing to listen that it could happen, if only with a minute probability, and even then most probably without casualties. At TMI it did not happen, for the very reason that scientists had predicted, whereupon the mentally slow burst into sobs because they had been misled, betrayed, hoodwinked, and abused.But with an HTGR things are, in any case, different. Should the helium leak out, the air will leak in; one would have to create a vacuum round the core to lose the coolant completely. And even then the metal cladding could not melt: There is no metal cladding. The fuel is imbedded in thick rods of graphite, a very stable material whose melting point lies above the temperature the thin fuel centers can reach. It would take hours, not minutes, for the fuel to be damaged by overheating.
There have, in fact, been two or three cases where forced circulation of the helium coolant was lost. It was restored after 12 to 15 minutes, but there was no hurry, for the massive heap of graphite has a high heat capacity and increases in strength as the temperature rises. In such an incident "you have literally a couple of days before things start to go bad," former NRC chairman J. Hendrie told a House subcommittee last March.
Yes, there have been plenty of mishaps as there always are in a new type of system. But most of them were not core-related; pumps and other equipment have been troublesome. The most memorable incident took place in January 1978, when some helium escaped. It may have entrained a quantity of radioactive iodine too small to measure, if there was any at all; what is so memorable about the incident is that CBS reported it as "A radioactive cloud is now moving toward Denver" (AtE Mar 78).
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Vol. 8, No. 5
Newsletter: Access to Energy Newsletter Archive Volume: Volume 8 Issue/No.: Vol. 8, No. 5 Date: January 01, 1981 04:53 PM (For actual publication date see newsletter.) Title: Controversial controversies
Copyright © 2004 - Access to Energy Newsletter Archive
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