Cool Thoughts on a Hot Nuclear Disaster Story

Despite the media hysteria and hyperbole from longtime nuclear energy opponents, the situation is Japan is not that dire.

While entire towns and villages along Japan’s northeastern coastline were wiped off the map by a devastating tsunami before the weekend, brought about by the largest earthquake in the nation’s recorded history; while thousands of people lost their lives and many thousands more, their homes and possessions, foreign news media are obsessing about the possibility of a nuclear meltdown occurring at a power plant in Fukushima Prefecture.

While the attention is hyped, it is understandable. Nuclear power accidents are potentially catastrophic and deserve reporting on. The rhetoric however has been totally overblown.

The European Union’s energy commissioner has characterized the incident as “apocalypse” and comparisons with Chernobyl are being thrown around like candy to longtime opponents of nuclear energy.

Japan has 53 nuclear power plants which provide more than a third of the country’s energy needs. The plants in the disaster area all shut down automatically when the earthquake hit Friday. The Fukushima facilities were the only ones that were seriously damaged.

The waves of the tsunami were too high for the protective seawalls built around the Fukushima plant which is located on the coast. The disaster probably destroyed the facility’s diesel backup power systems. While the actual reactor was unaffected, because of a lack of power, the plant’s pumps failed.

Normally, when a reactor is shut down, it can take more than a week for “decay heat” from traces of radioactive isotopes to cool down. The core’s fuel rods must be continually bathed in cooling water during that time to prevent overheating. This is what went wrong at Fukushima.

Because the pumps failed, the coolant water in the reactors overheated and began to evaporate. Engineers had to release pressure by venting radioactive steam which contained an otherwise harmless level of radiation.

The explosions that occurred at the Fukishima plants were hydrogen explosions. While damaging the plant’s infrastructure, these bore no immediate health risks.

If engineers at the plant do not manage to cool down the reactors, their water levels will drop and expose the fuel rods, leading to a meltdown. This would cause the rods to melt to the bottom of the steel and concrete containment vessels surrounding the reactors but still pose no immediate threat to the general population. The containment structures are powerful enough to withstand even the extreme temperatures of a full meltdown.

It is possible that one or several of the containment vessels of the Fukushima facility were damaged during the quake. A spokesperson has said that one spike in radiation levels was “probably” caused by damage to the container. If that is true, people in the vicinity of the plant could be exposed to harmful levels of radiation.

The government therefore ordered the evacuation of residents within a twenty kilometer radius from the Fukushima power plants. Tens of thousands of people had already left the area.

If a meltdown happens, the decay heat from the reactor must still be absorbed. Japanese engineers have reportedly used sea water to flood an entire containment structure. This causes irreversible damage to the reactor but should prevent further steam releases and with it, releases of radiation.

The incident at the Fukushima facility is utterly incomparable with the Chernobyl disaster.

The Ukrainian plant was very different from the Japanese in that it had no containment structure and used graphite instead of water to moderate the nuclear reaction. It was the graphite that caught fire in 1986 and because of the lack of a container, radiation was immediately released into the atmosphere.

The radiation released in Japan so far has not been excessive and is highly unlikely to have hurt anybody.

As a precaution, authorities have distributed iodine tablets which help minimize the damage incurred by breathing radioactive iodine which is a component of nuclear fallout.

Technically, this hasn’t been necessary. If people are to be exposed to unsafe levels of radiation as a result of the radioactive steam that was released from the Fukushima plants, it will be because they drank contaminated water or milk. This is a health hazard authorities should, and will, be looking out for.

Update: After this article was published it was reported that the pool containing spent nuclear fuel in at least one of the Fukushima reactors was without water, causing unusually high radiation levels. Japanese officials denied this.

The pools may be a greater danger than the reactors because they are not contained. The roofs of two of the plants at Fukushima were lost in hydrogen explosions moreover, exposing the spent fuel pools directly to the atmosphere.