This is a reproduction of the article that was just published in this month’s SACOME journal. It was jointly authored by myself and Barry Brook. It is the second is a series of six articles we are providing the journal. As ever with the media, we write to a word limit. Try not to get cranky if you think something is under done, use the comments section instead!
Safety is a major public concern for nuclear power. There is no quick way to overcome this feeling. But a few facts certainly can’t hurt.
The nuclear power industry has an excellent operational safety record. A major actuarial study conducted by the European Commission over 15 years examined 4,290 energy-related accidents across different technologies. They found the following: coal kills 25 workers per terawatt hour (TWh) of energy delivered, oil 36, gas 4, and hydro, wind, solar and nuclear all less than 0.2 deaths/TWh. They state “expected fatality rates are lowest for western hydropower and nuclear power plants”. So, permitting ourselves to think in the context of the alternative energy supply options, there is no argument; nuclear power is very, very safe.
Serious nuclear accidents have happened. The Three Mile Island reactor in the US experienced a partial meltdown of the fuel. The reactor pressure vessel was not ruptured, however, and the containment dome held the majority of the gaseous releases within the reactor building, but the core partly melted and was a write-off. No one was killed.
A much worse incident occurred in 1986 at Chernobyl, Ukraine. During a poorly planned experiment where the safety systems were deliberately disabled, a massive power surge blew the top off the reactor and triggered a fire in the graphite moderator. This Soviet-era design lacked a concrete containment dome, and the wind-driven smoke carried a plume of radioactive particles over Europe. The accident and its immediate aftermath killed 28 emergency workers. Among local children and adolescents, exposed to highly elevated doses of short lived radioactive iodine in milk, more than 6,000 cases of thyroid cancer were observed. The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has recorded 15 cases that have proved fatal. They also state “…there has been no persuasive evidence of any other health effect in the general population that can be attributed to radiation exposure”. For most, these findings from the peak global body are surprising. It’s anathema to those who want dread of nuclear and ionizing radiation to prevail. But facts are persistent things.
This year, an extreme natural force disabled the 40-year old reactors of Fukushima Daichi and destroyed all back-up power supply. Prolonged loss of cooling led to a meltdown and the release of radioactive material in vented steam as well as possibly through some breached containment. There have been no nuclear-related fatalities. Suitable precautionary measures for residents were taken, and the radiation released was 4.5 per cent that of Chernobyl. The possibility of any latent fatality is exceedingly low.
These accidents frightened us more than they hurt us. But that does not make them ok. What safety features could we expect from modern reactors if Australia adopted nuclear power?
Passive safety systems – banking on the laws of physics
Modern reactors cannot run out of control in the way Chernobyl did because water plays the role of both the coolant and the moderator. If the coolant cannot shed heat, the water expands and moderation is reduced. The reactor loses reactivity and power levels decrease.
New reactors include safety systems that rely on natural processes. For example, the core-cooling tank in the AP-1000 design has valves held shut by AC power. During station blackout, emergency water is channeled into the reactor core by gravity, and re-circulated through passive convection and condensation. This class of reactors, known as a called Generation III+, are also built to a standardised design, with most component modules pre-fabricated in a factory and then assembled on site. These quality controls reduce cost but also enhance reliability and safety.
These improvements make a big difference. Probabilistic risk assessment put the risk of core damage from design-basis events as 1 in 20,000 reactor years for a 1970s design. For the AP-1000, it’s 1 in 24 million. Already engineered to be among the safest of power sources, today’s designs are three additional orders of magnitude safer.
Yes, there is some risk that a terrorist could hijack an aircraft, hit a reactor with pinpoint accuracy, breech containment, and cause the release of nuclear material. It’s just an incredibly low risk. Our society functions by making rational decisions about risk. Nuclear power is no different.
Many fear the impact of low-level, long-term exposure to radiation. Well, we already have such exposure; ionizing radiation is natural and with us every day. So it is pertinent to consider how nuclear power plants might affect this exposure.
UNSCEAR says the additional radiation exposure for those living in the vicinity of nuclear power plants through non-accident trace releases is 0.0002 millisieverts (mSv) per year, compared to a background level of 2 to 4 mSv per year (this depends on where you live). So it works out that 1/15,000 of your total yearly dosage could come from nuclear power. As far as meaningful risk goes, this one truly is not worth the worry.
As the conversation around nuclear power in Australia builds, fear will give way to a desire for information. In a fact-based discussion on safety in energy, nuclear proponents need not fear.