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Wednesday, November 29, 2006

Stephen writes on the viability of nuclear power

I thought it might be helpful to discuss some of the good and bad bits about nuclear energy given the current events in the Australian Commonwealth Government (Canberra). Al Gore said it, now the Oz government's own advisor has said it, nukes are expensive. My position is that nukes have their place but only for the short term; which given the cost might rule them out under my own criteria.

But I feel that before we can discuss the issue rationally I need to clarify a couple of BIG misconceptions about the dangers of nukes (used for electrical power that is).

Modern nuclear power plants, and I will include 3 Mile Island in that category, are seriously contained. That is, there is a shell built right around the reactor vessel designed to contain the mishaps of fault conditions. Even back when they designed 3 Mile Island, the containment designers considered jumbo jets crashing into them (accidental crash, nor terrorism). The event at 3 Mile Island was contained, as designed. What actually happened was that a pressure relief valve stuck open and the control room operators didn't know it was stuck open (they expected it would spring closed like they usually do). Water got into the reactor system and caused a shut down. Although the neutralising rods automatically used to stop the neutron release in the reactor did their job, there is always a small residual neutron flow from the core that takes a couple of days to disipate - but it was enough to produce a "cloud" of radioactive waste INSIDE THE CONTAINMENT VESSEL.

The media beat this up - it sells lots of papers and TV, someone filmed a {safe and normal} condenser steam release and said there was a toxic cloud release. Hysteria took over, and the US stopped building nuke power plants.

Chernobil was not originally an electrical generating plant, it was an enrichment plant for atom bombs. Later the USSR turned it into a power plant and guess what... it never had a containment shell. To make matters worse, someone in the Cremlin (no doubt with the powers to sent dissenters to Siberia) told the operators to test a shud down to see how long they had to find alternalte electrical supplies. To effect the shutdown, the operators had to OVER-RIDE the safety interlocks. A series of technical errors in the "experiment" meant that the reactor needed to be more quickly controlled but without the safety interlocks... well we all know the rest.

Now we all accept that Australia is a more exempliary place that the old USSR. Canberra is not likely to require silly experiments and we would use protective shells around our reactors. And speaking as an engineer, I am confident the current safety systems and designs and testing are much better than back in the 60s. But the cost; I shudder to think.

Then there is the concern about the waste taking 60,000 years to decay to a safe level. Well yes that is the case for old fashioned U235-6 reactors, but with the modern fast reactors using U233, the decay times reduce significantly to 2000 years. Still sounds bad, but lets keep it all in perspective. Yet again, the cost...

My reading of the engineering literature suggests that India seems to have these plants down to a fine art. The risk managers talk of 3 Mile Island type faults being a 1 in 40,000 year event. Well global warming is a current event. We are having a 1 in 1000 year drought. I think we need to give the technology a good hearing. I must be a miser or something because I can see a huge increase in my power bill coming. Perhaps it will make it cost effective for me to buy a solar electricity system for my home.

BTW, I wonder if Johnie's attitude to carbon trading changed when he read the advanced draft of Ziggie's report and worked-out that he would need a carbon tax to make it all cost possible.

Kindly, Stephen


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