Where to now in solving nuclear waste problem?
ANALYSE THAT - TIM BROWN
Despite our searches, we have yet to find a power source that does not have a downside. Even renewable resources such as wind, sun and water all have costs in some form. There are no free lunches in the power-supply business.
Nuclear power has been used successfully for many years in many parts of the world.
Britain's plants have been operating without problems for more than 55 years. There have been only two major accidents, at Chernobyl and Three Mile Island.
Public pressure caused the closure of four plants in Italy and that resulted in Italy being held to ransom for power by Russia. An Italian nuclear engineer reliably advises me that the new reactors are environmentally friendly.
That, however, is not the problem. Nuclear waste remains for a long time, up to 100,000 years.
There are 10 "orphan dump sites" in the United States. These are sites where the reactor has long since shut down, leaving graveyards of steel and concrete casks which need constant monitoring. Chernobyl still has a regular full-time staff on duty 23 years later to monitor further radioactive release.
The US has at least 66 commercial and 55 military used-fuel storage sites. The number in what was the Soviet Union and China can only be guessed at.
The evolution of smaller and safer nuclear plants does not help us to deal with the already amassed nuclear waste. The decommissioning of plants increases orphan dump sites.
The producers of these sites are no longer on the spot and no longer care. They have their new plants.
In a previous column, I quoted many, including my Italian nuclear engineer friend, who said that the maintenance of modern industrial nations, with the material and commercial outputs we demand, is impossible without nuclear power. The human race has learned from the scars of the Industrial Revolution to clean up mining and industrial sites after they have served their purpose. (I'm sure we could do this in New Zealand to access the recently described mineral riches present in our National Parks. However, there would be a PC outcry.)
Lets us look at the science and engineering involved. Relatively harmless uranium oxide fuel is introduced into the reactor in the form of small pellets. Once it is lowered into the reactor, the process may run for two years, after which the fuel is moved around, with the older fuel being removed. One batch usually stays for three to six years. When removed, the fuel assembly's highly radioactive products, such strontium 90 and caesium 137, generate a large amount of heat.
These fission products burn hot for a short time and are kept in very clean water. Their half-life is short – just years. The long-term challenge is to deal with the actinides, which are the products created by uranium absorbing a neutron and refusing to split.
These products have half-lives of hundreds of thousands of years. They constitute only 1 per cent of the product, but are dangerous – 3.4 per cent of the fission products decay to safe levels after 300 years.
What are the options: storage underground or in concrete containers or recycling? Recycling turns waste into more power, but at a high cost. US presidents Gerald Ford and Jimmy Carter banned this option because Third World thieves and terrorists could use the plutonium to make bombs.
Now, research is designing plants which speed up the decay chain and recycling. These plants are yet to be put through their paces and their cost is still prohibitive.
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