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Th e Zirconiu m

Connectio n

by Daniel M. Piselio

The vast majority of nuclear reactors are operating with a

fatal design flaw. The

reactor fuel must be sheathed in cladding, and the material currently used in Light Water Reactors is an alloy of the metal zirconium. This alloy has the dangerous

property of reacting ex­ plosively with water. Yet there is no other material

that can replace it.

The inherent dangers of zirconium cladding have been the object of a massive and insidious cover-up on the part of the American nuclear industry and the United States Nuclear Regulatory Commission (NRC). The recent accident at the Three Mile Island reactor in Harrisburg Pennsylvania has brought to light both the design flaw and the extent of attempts to conceal it . Al l Light Water Reactors (LWR) — both the Pressurized Water (PWR) and Boiling Water (BWR) types — are affected by this flaw. According to the World List of Nuclear Power Plants published in Nuclear News, February 1979, all but one of the 68 plants in the United States are LWRs. The same source indicates that 85% of the nuclear power plants in the world outside of Great Britain are LWRs. Great Britain has currently no LWRs, since its own powerful nuclear establishment has so far

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resisted the world-wide marketing efforts of the American nuclear industry.

Three Mile Island

The dangers of zirconium are well illustrated by the events at Three Mile Island. Mechanical difficulties, the details of which are not of crucial importance here, led to a partial loss of coolant, and a partial meltdown of the reactor core (see The Ecologist, May/June 1979). As an emergency measure, reserve cooling water was sprayed onto the dangerously exposed and overheated core. Several days later i t was reported that a huge bubble of flammable hydrogen gas had formed unexpectedly inside the reactor vessel. This bubble not only inter­ fered with efficient cooling of the damaged core but also presented the frightening possibility of a hydrogen explosion whose likelihood increased hourly as the oxygen concentration in the bubble approached a critical level. Such an explosion would have ruptured the containment vessel, precipitating a meltdown and resulting in large scale and long term contamination of the atmos­ phere and the Susquehanna River valley. Spokesmen for the utility company and the NRC claimed ignorance on the subject of the origin of the hydrogen bubble, referring to i t as a "new twist" and "something that had not been forseen when the reactor was designed". The next day the bubble shrank and disappeared. The American media carried the story of the disappearance but gave no explanation, indicating only that its

disappearance had been more rapid than expected.

Lying their way out of Trouble

The claims of ignorance and the pretension of mystery on the part of both the utility company and federal experts in regard to the appearance and disappearance of the hydrogen gas are quite simply lies. Explan­ ations for these occurrences are commonly available in the literature on nuclear engineering and safety, and centre around the use of zirconium alloy cladding.

Experts within the American nuclear establishment are admitting privately that they are certain that the hydrogen was produced by the reaction of tons of zirconium clad­ ding with the steam formed in the reactor vessel during the early stages of the accident. Weeks after the event the only public reference to the role of zirconium in the produc­ tion of the hydrogen bubble was in the British press. (Recall that of all the major nuclear powers only the United Kingdom has no LWRs.) The April 12 issue of Nature magazine referred to a recent letter to The Guardian by Sir Martin Ryle of the Cavendish Laboratory in Cambridge, who stated that a highly dangerous hydrogen bubble should have been predicted as a matter of "A-level textbook knowledge". The following excerpt is taken from a standard textbook on reactor safety and is part of a report dated February 1969:

The chemical reaction of the cladding with steam, which is supplied by the water remaining in the bottom of the primary vessel after the blowdown has three important effects. First, i t