Japan relies on nuclear power for about 30% of its electricity. It has few natural resources and imports large quantities of coal, gas and oil at an ever increasing cost. Some Japanese people are not in favour of nuclear power, but when the dust settles the nation might not have any real choice.
Losing four old reactors at Fukushima that were due for replacement is not the end of the world, and certainly not when you consider the huge loss of life and enormous damage wreaked by this month’s earthquake and tsunami.
Japan built its 55 nuclear reactors over a period of decades (the damaged reactors in Fukushima are some of the world’s oldest still in regular operation, based on early commercial designs).
Nineteen began operation in the 1970s (Fukushima-Daichi-1 dates from 1971); fifteen began life in the 1980s; thirteen in the 1990s; and five in the “noughties”.
Of course, one might question the logic of building reactors in earthquake zones, but in the end the primary reactor structures in Fukushima were not directly damaged; nor have they been damaged in previous quakes.
One could also ask what would have happened to other sorts of power stations (particularly dispersed ones such as wind farms or solar cell arrays) in such an event. My guess is that they all would have been swept away.
All thermal power stations are based on similar principles: they produce heat by burning something (coal or gas for example) and convert the generated heat to electricity.
The big advantage of using nuclear reactions such as fission is that one fission produces about 100 million times more energy that you get from burning a single carbon atom.
Coal-fired power stations have to burn a lot of material (about three million tonnes a year) to generate electricity for a city of a million people, and about 10 million tonnes of carbon dioxide are released to the atmosphere in the process.
Nuclear reactors, by comparison, consume only one tonne of the fissile uranium isotope, U-235, to deliver the same.
There are currently 441 large nuclear power reactors in 35 countries, 120 of which date from the 1970s and early 1980s.
Collectively the 400-odd reactors supply about 15% of the world’s electricity (the average in OECD countries being more than 22%). So far they have racked up more than 14,000 reactor-years of operation.
The United States has the greatest number operating, with 103 units providing 20% of its electricity supply; this is followed by France with 57 (producing nearly 80% of its supply) and Japan, with 54 (providing about 30%).
With a lifespan of approximately 35 to 40 years, some have pointed to the fact a nuclear station decommissioning “peak” will occur from 2020 to 2030, and that this will present technological and environmental challenges. In my opinion these challenges will be met.
Of the reactor types, 22% are either Boiling Water Reactors (BWR) or Advanced Boiling Water Reactors (ABWR) while 62% are Pressurised Water Reactors (PWR) of different hues.
Most of the remaining reactors are the Canadian designed CANDU systems (or their derivatives in India) that operate with heavy water and natural uranium, or the AGR (graphite moderated, gas cooled) reactors developed in the UK from the early Magnox (metal fuel) reactors.
Newer models (those you would buy off the shelf if you went shopping for one today) are more modular, smaller, simpler with fewer pumps and valves etc., and they have what are called “passive” safety features.
These features are very important because they mean that you can continue to cool the reactors, even if you lose all electricity supply.
Dramatic advances in computers in the last two decades have also had a major impact on the control systems for reactors, improvements that are gradually being retrofitted to existing reactors, expanding their ability to diagnose and cope with issues that might occur through foreseen or unforeseen circumstances.
This will have a significant impact on the training of reactor staff, who already have available to them full-scale simulators that mimic real and imagined events, and on the capacity of the industry to share technological information.
The standardisation to a few reactor designs will also help the move towards international oversight and analysis of safety issues and approval of designs; this in turn will take some of the burden off individual countries that might be temped to reinvent the wheel.
What happens now?
Of course, the ongoing Japan crisis is not an easy situation to deal with and will doubtlessly have repercussions for the entire nuclear industry. Already, countries with significant nuclear installations are looking at the age of their fleets in the light of what has happened here.
Germany, which gets about 28% of its electricity from reactors, has paused operation of its older reactors until they can be re-evaluated.
China has temporarily stopped construction of the many new reactors it has on its drawing boards – currently 34 approved with work on another 26 initiated – and the UK is going to look again at its plans.
But the likely result of these and similar actions in other countries is a pause, rather than a cancellation of nuclear reactor production.
The Chinese government, for example, might worry that it cannot meet any of its carbon-emission targets without a large-scale low-emissions technology such as nuclear.
The needs for stable large-scale electricity supplies and lower carbon emissions are issues that won’t go away easily, not for any nation.
Nuclear has long been part of the solution, and I believe this remains the case.