Weighing up nuclear power

1. A nuclear power station generates electricity using energy released inside its uranium fuel, so no fuel is burned and the station's advantages and disadvantages are quite different from those of a coal or gas station.
2. An evaluation is not a list; it sets advantages against disadvantages, gives a reason for each, and ends with a judgement that follows from those reasons.
3. Several of the arguments turn on risk, which combines how likely harm is with how serious that harm would be if it happened.
4. Nuclear power sits at one extreme of that combination: the probability of a major release is very small, but the consequences would be very large, which is why people disagree about it so strongly.
5. Five areas have to be covered in a full answer: carbon dioxide emissions, reliability, the risk of an accident, radioactive waste and safety, together with how the public sees all of these.

Carbon dioxide emissions

1. Nothing is burned while the station is running, so generating the electricity releases no carbon dioxide, and no sulfur dioxide or smoke particles either.
2. Carbon dioxide is a greenhouse gas, so electricity generated this way makes a much smaller contribution to climate change than the same electricity from coal or gas.
3. Nor does it release the sulfur dioxide that causes acid rain, which is a further advantage over burning coal.
4. Looked at over the whole life of the station, though, the emissions are low rather than zero.
   1. Mining, processing and enriching the uranium all use energy that today mostly comes from fossil fuels.
   2. Making the enormous quantities of concrete and steel for the buildings releases carbon dioxide.
   3. Fuel and waste have to be transported, and the station has to be dismantled at the end of its life.
5. Even counting all of that, the carbon dioxide released for each unit of electricity is far below that of a fossil-fuel station, so the advantage is real; the accurate phrase is low carbon rather than carbon free.

Reliability and fuel

1. The output does not depend on the weather, so a nuclear station can run at close to full power day and night for months at a time, which wind turbines and solar panels cannot.
2. This makes nuclear useful for the base load, the steady demand that never goes away, so a country using a lot of renewable generation still has a supply when the wind drops.
3. An enormous amount of energy is released from each kilogram of fuel compared with coal, so only a small mass of fuel has to be mined, transported and stored each year.
4. Because so little fuel is needed, the cost of the fuel is a small part of the running cost, so the price of electricity is not pushed about by fuel prices in the way gas generation is.
5. Uranium is a finite resource that has to be imported, so nuclear power is not renewable and does not remove every question about long-term supply.
6. A reactor is also slow to start up and shut down, so it is poorly suited to following sudden changes in demand.

Risk of an accident

1. A working station holds a very large quantity of intensely radioactive material inside its reactor and its fuel stores.
2. If the containment failed, radioactive material could escape into the air and into rivers or the sea, spreading over a wide area as dust and rain.
3. People nearby would receive a large dose, and thousands might have to leave their homes, in some cases permanently.
4. Where the escaping isotopes are long-lived, farmland, water supplies and buildings can stay unusable for decades.
5. The accidents at Chernobyl in 1986 and Fukushima in 2011 are the events usually quoted, and both led to large exclusion zones.
6. Such accidents are very rare, and measured against the electricity generated worldwide the number of deaths caused by nuclear power is far smaller than the number caused by air pollution from burning coal.
7. A fair judgement therefore uses both halves of the risk: a very low probability combined with a very severe consequence.

Radioactive waste

1. Waste is sorted by how active it is, and the three levels are handled very differently.
   1. Low level waste, such as used gloves, tools and packaging, is only slightly active and is compacted and buried in lined, monitored surface sites.
   2. Intermediate level waste, such as reactor components and metal fuel cladding, needs shielding and is set in concrete inside steel drums.
   3. High level waste, the used fuel itself, is intensely radioactive and generates so much thermal energy that it has to be cooled for years before it can be moved.
2. Used fuel is first stored under water in cooling ponds on the site, where the water absorbs the radiation and carries the thermal energy away.
3. It is then sealed into glass or ceramic blocks inside corrosion-resistant containers, which stops the material dissolving or blowing away.
4. The long-term plan in most countries is deep geological disposal, burying the containers hundreds of metres down in stable rock away from groundwater.
5. Some of the isotopes in the waste have half-lives of thousands of years, so it must stay isolated for longer than any human structure has ever survived.
6. This is the strongest argument against nuclear power: the electricity is used now, but the cost and responsibility of guarding the waste fall on future generations who gained nothing from it.

Safety systems and cost

1. Because the consequences of a release are so serious, a station is built with several independent barriers rather than relying on any single one.
   1. The fuel is sealed in metal cladding, which is enclosed in a thick steel pressure vessel, which sits inside a reinforced concrete containment building.
   2. There are separate emergency shutdown systems and back-up cooling with its own back-up electricity supply.
   3. Radiation levels are monitored continuously on the site and in the surrounding area.
   4. Staff are trained and the whole site is inspected by an independent regulator with the power to shut it down.
2. All of this makes a nuclear station expensive and slow to build, often taking well over a decade from decision to first electricity.
3. At the end of its life the station has to be decommissioned, which means dismantling radioactive structures over several decades and paying to store what is removed.
4. So although the fuel is cheap, the electricity is not cheap once building, safety and decommissioning are counted across the whole life of the station.

Public perception

1. Public perception is how large people believe the risk to be, and it is often quite different from the risk the measurements show.
2. People judge a hazard as worse when it is unfamiliar, when it is invisible, when the harm might appear years later, and when a single event could affect very many people at once, and nuclear power has all four of these features.
3. Major accidents are reported worldwide for years afterwards, whereas the steady harm done by air pollution from fossil fuels is rarely reported at all, so the two are not judged on the same scale.
4. Perception has real effects: local opposition can delay or block a new station or a waste repository, and public opinion after an accident abroad has led some countries to close their reactors early.
5. Opinion is not simply an obstacle to be argued away, because the people who live near a station are the ones who would carry the consequences, and in a democracy they have a say in the decision.
6. The scientific evidence on emissions, doses and accident rates informs the decision, but it does not make it; that is a choice for society.