Roger Hanson: Nuclear Power – yes or no?

Thursday, 4 May 2017

The 1986 Chernobyl meltdown is the most high profile in a series of major issues at nuclear power stations.

In the late 1930s it was shown that by firing a neutron at a large atomic nucleus it could split the nucleus and release vastly more energy than that of any chemical reaction.

This process is called nuclear fission. Ominously, its first application was a nuclear bomb.

Following the Fukushima catastrophe, 80 per cent of the Japanese people interviewed said they did not want Japan to continue with nuclear power.

Subsequently, the energy from nuclear fission has been used to generate electricity and in the 1950s nuclear power was touted as the dream energy source.

The energy bonanza offered by nuclear fission makes nuclear power compelling.

* Roger Hanson: Still one of the world's fastest aircraft

* Roger Hanson: Isambard Brunel: An engineering inspiration

* Roger Hanson: Moon missions come with unexpected hazards**

In addition it doesn't generate greenhouse gases, it works in all weathers and therefore provides a reliable base-line electrical power load. But, there are major disadvantages with nuclear power.

Firstly, nuclear waste. The atomic nuclei from unstable chemical elements randomly lose energy mainly by emitting radiation – such elements are radioactive and this process is called radioactive decay.

The time taken for a quantity of radioactive material to decay sufficiently that it can be considered safe, varies considerably depending on the chemical element.

Although some of the the short lived fission products are dangerous they don't last long, for example, xenon-140 is safe within minutes.

The problem lies with the medium lived (30 years+) and long lived (100,000 years+) radioactive elements.

When an atom of the most common nuclear fuel, uranium-235 is split by a neutron, fission products are produced, typically caesium-137 and strontium-90.

These remain dangerous for many decades.

A particularly potent group of waste products are the minor actinides – they're dangerous for well over 100,000 years and must be shielded from the biosphere for that length of time before it is safe.

To date, no convincing long term solution for containment of nuclear waste has been found.

A further problem is to find a place to store nuclear waste where there is no resistance from the local community.

Secondly - proliferation. The waste products of these nuclear power stations include chemical elements that could be used to make nuclear bombs.

If nuclear reactors become very widely used then it is reasonable to assume that sooner or later some of this material will eventually be used by many more countries to make nuclear weapons, further increasing the nuclear threat.

Thirdly, safety. As with any chemical plant, accidents happen - the problem with nuclear power plants is that the consequences can be catastrophic – Chernobyl and Fukushima are examples.

The record shows that stray low grade leaks occur fairly frequently – for example, from coolant water pipes.

More significant leaks have occurred, for example six serious incidents between 1950-2000 from the Sellafield plant in the UK.

Fourthly, the cost. The full cost of building a nuclear power station is astronomic and includes construction costs, annual operating costs, the cost of storing the waste and finally, decommissioning the facility.

Decommissioning means dismantling the facility such that it no longer requires people to be protected from radiation.

The cost of at least two nuclear plants currently under construction, and years overdue, are each running at more than triple the initial estimate - Flamanville in France and Olkiluoto in Finland.

The 2012 estimate for Flamanville was NZ$5.2 billion the current estimate is NZ$17 billion.

Weighing up the pros and cons, the conclusion is that a country has to be desperate to consider nuclear power generation especially since we're on the brink of a technical revolution in battery storage capacity.

In the near future it is hoped that batteries will enable the energy from wind and solar sources to be easily and cheaply stored on an industrial scale, allowing renewable energy to meet base-line electrical load demand – side lining nuclear power.

The most nuclear power dependent country in the world is France – 77 per cent of its electricity production is nuclear, Sweden (40 per cent), Finland (30 per cent) US (20 per cent), UK (18 per cent) and China (3 per cent). Post Fukushima, 80 per cent of the Japanese people interviewed said they did not want Japan to continue with nuclear power.

Germany has promised to close all its nuclear power plants by 2022. New Zealand is in the enviable position that nearly 80 per cent of its electrical power comes from renewable sources, mainly hydro dams, consequently, there is no need to ever consider nuclear power here.