Why Absolute Safety of Nuclear Reactors is impossible?

Prof.T.Shivaji Rao,

Director, Centre for Environmental Studies,

Gitam University, Visakhapatnam-530 045

When the Swiss Government wanted to buy the US Reactors in 1973 , they demanded experimental proof that the dome containment would retain the radioactive pollutants released during a Loss of Coolant Accident (LOCA) Besides being expensive, since an actual test would be more dangerous than nuclear bomb testing, assurances on reactor safety are entirely based on tests on paper using simulated mathematical models. As such test results can not take into account the different permutations and combinations of malfunctions from defective materials, mechanical or human errors, sabotage, bombing, terrorism, missile hits, aero-plane crashes etc. they become invalid.

In other words, nobody can do all the necessary testing nor even anticipate what kind of tests are needed. At best, the experts may be able to simulate and estimate the answers to some of the questions asked by the people but do the people know all the questions that are yet to be asked for making the reactors absolutely safe for all time? Hence the proof of reactor safety could not be given and still has not been demonstrated.

But when the tests on the Emergency core cooling system designed to flood the core during a loss of coolant Accident were run at the National Reactor Testing Station in Idaho, mechanical failures occurred. When the tests were run during 1970-71 all the six tests conducted by the Aero-jet Nuclear Company failed. Subsequent experiments at Oak-ridge National Laboratoreis indicated that the Zircaloy-clad fuel rods of the Light water reactors may swell, rupture nd block the cooling channels, and thereby obstruct the emergency cooling water from reaching the core and such obstruction which holds back the emergency core cooling water leads to a catastrophe sometime or the other. Thus reactor safety is most often a myth!

Accidents in Atomic Waste Storage Tanks!

As a temporary measure most countries are storing highly radioactive wastes in steel and concrete tanks on the surface of he earth. The fuming nuclear wastes produce 9 kilo-watts of energy by radioactive disintegration per cubic meter and hence must be cooled all the time. However accidents occur in the storage tanks as detailed below.

1) The chemicals in the radioactive liquid wastes often cause corrosion of the containers. As a consequence of such corrosion, nearly half a million liters of radioactive waste seeped into the ground from the storage facility at Hanford Washington (USA).

2) If the refrigeration systems that cool the storage tanks fail due to power shortage, floods, earthquakes, human or mechanical failures or sabotage, the contents of the storage tanks would heat upto about 1000^oC (1832^oF) and cause an accident that would render an area double the size of Switzerland uninhabitable for many decades.

3) The water molecules in the storage tanks are split into Oxygen and Hydrogen due to radiation. If the ventilation system of the tanks were to fail and Hydrogen reaches the lower limit for explosion of 4% in the air, an explosion that can destroy the tanks along with refrigeration systems may occur.

Thus the location of he atomic waste storage tanks on ground surface is beset with substantial risks due to accidents that may cause serious radioactive pollution of air, water and the soil resources in the nearby and distant environments.

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