As a result of an earthquake NE of Japan, grid power was disrupted and a tsunami flooded the diesel backup generators at the Fukushima nuclear power facility. After several days of struggling to cool the reactors, staff have been withdrawn. Extraordinary measures could not reverse the damage:
- automatic shutdown promptly at the time of the earthquake,
- use of portable pumps for seawater plus boron compounds (to absorb slow neutrons),
- withdrawing all but essential staff, and
- finally withdrawing all staff.
Many mistakes were made as is usual in train wrecks:
- fuel ran out for a pump allowing water levels to drop, and, of course,
- the backup generators were not placed high enough to avoid the tsunami.
For those who do not understand the operation of a fission reactor, a few facts:
- some atoms of uranium split into two or more smaller nuclei plus radiant energy and fast neutrons,
- if the fast neutrons are slowed by a moderator such as water, or carbon, the speed can be slowed so that the neutrons will be captured by other atoms and trigger further splitting, a chain reaction,
- given the right geometry and concentration, the chain reaction can grow explosively as in a bomb or at a constant rate in a reactor,
- the radiation (alpha, beta, neutrons, fission products and gamma rays) eventually is transmitted to the surroundings as heat, normally used to produce electric power in steam turbines, and
- the principal control of the reaction is by control rods, usually cadmium, that absorb neutrons without fission.
When the control rods were automatically inserted by the control system, the neutron-triggered chain reaction is greatly reduced but the radioactivity of the fission products is locked in the core of the reactor and produces hundreds of megawatts of heat, no matter what the operators do. In this case, the operators were not able to keep cooling water passing through the core and overheating caused melting or cracking of the fuel bundles, allowing fission products to escape into the water which escaped containment as jets of steam. Further, used fuel bundles which were in storage also ran dry and caused hydrogen and steam explosions to wreck buildings and injure staff.
The radiation levels reached are now dangerous to life within an hour or two so it is no longer feasible to keep staff on the job steadily. They might rush in briefly to monitor the situation but as much as possible must be done by remote monitoring.
The worst-case scenario is the water cooling failing completely, the water being converted to steam and the fuel bundles melting down permitting huge escapes of radioactive isotopes. The ones being monitored are likely Caesium137 and Iodine 131. Both are readily absorbed by humans and can cause cancer and or accute radiation poisoning. The radioactive iodine can be rendered ineffective by taking large doses of normal iodine as potassium iodide as the probability of absorption is greatly reduced. If not absorbed by the thyroid gland, iodine is secreted rapidly. These materials have been reported in low concentrations as far away as Tokyo. If the cores melt down, a large region of Japan may become uninhabitable just as in Chernobyl. There are several reactors in Japan all going at once, it seems.
These events are clear evidence that when things go wrong they go wrong in the worst possible way and that any system designed by humans is faulty.
We still don’t know the outcome. If staff cannot work on the system Nature will take its course and meltdown is likely. This could release dangerous amounts of radioactive material in the neighbourhood and depending on wind and rain the habitable area of Japan could suddenly be reduced. It may be necessary to sacrifice staff to save the general population but there is no guarantee such sacrifice would be rewarded with a better outcome. The monsters cannot even be buried until they cool down. The steam will still issue. The air and water and land will still be contaminated. There is just no way to turn off the production of heat for many weeks. After that it can be encased in concrete but the long-lived radioactive isotopes dispersed in Nature cannot be recovered, only diluted or bull-dozed into piles.
Pray for a west wind in the coming days.
see also BBC