The crisis at Fukushima Daiichi nuclear power plant has yielded the top news spot to the events in Libya for now, but it’s far from over. “Factually, the problem in Japan is only just starting, ” Sebastian Pflugbeil, a physicist and president of Gesellschaft für Strahlenschutz (Society for Radiation Protection, Germany) is quoted by German magazine Focus.
To secure Fukushima Daiichi, a total of 3 reactor cores (1, 2 and 3) and 4 spent fuel pools (1, 2, 3 and 4) need to be brought permanently under control. If any one of these cores or spent fuel pools goes into full melt down, high levels of radiation from destroyed fuel rod assemblies may pollute the reactor site so much that staff will be forced to indefinitely abandon the entire plant, including control rooms and cooling equipment of units currently in a semi-controlled state.
On Tuesday Tepco reconnected power to the damaged reactor blocks in Fukushima Daiichi, but it is still a long step from being able to turn on lights in control rooms to actually running massive cooling pumps in the damaged plant.
Keith Bradsher writes in the New York Times:
Preventing the reactors and storage pools from overheating through radioactive decay would go a long way toward limiting radioactive contamination. But that would require pumping a lot of cold freshwater through them.
The emergency cooling system pump and motor for a boiling-water reactor are roughly the size and height of a compact hatchback car standing on its back bumper. The powerful system has the capacity to propel thousands of gallons of water a minute throughout a reactor pressure vessel and storage pool.
These pumps first need draining of air pockets to be able to be operated again, which is a difficult process under ordinary conditions, when the core isn’t damaged yet and radioactivity in the water of the primary cooling cycle is relatively low. Now the risks to the technicians will be tremendous.
It has also been reported that the pumps in unit #2 are no longer usable and replacements have been ordered. Any effort to remove the dead pumps, move in new pumps and reconnect them to the piping is going to be a real challenge under current conditions.
A couple of days ago the first reports came in of low doses of radiation in drinking water in Tokyo, then still around 1% of legal limits. That was after winds for the first time since the accident had blown south from Fukushima towards the Kanto area, the flat plain surrounding Tokyo. Later they turned back out towards the sea.
This week the winds from the north returned. Radiation levels in drinking water in Tokyo that exceed Japanese legal limits for infants below one year old have now alerted many to the risks. Tap water should no longer be used to mix with infant formula, but stores have run out of bottled water. What are mothers going to do? Boiling does not destroy radioactivity. Tokyo gets much of its drinking water from dams in the mountains west of the city, such as Lake Okutama, which get replenished by rain.
The Kanto plain is home to about as many people as live in Canada, California or Spain. What are they going to do without safe drinking water?
For lack of available fresh water, sea water has been used for cooling at Fukushima for almost two weeks now. Each ton of sea water contains about 35 kg of salt, which stays behind when the water boils off or evaporates as steam. Gradually the inside of the reactor cores and storage pools will become silted or encrusted with solid salt. Sooner or later the efforts to cool the reactors won’t be sustainable without ample supplies of fresh water.
Time is running out in Fukushima.
- New Problems at Japanese Plant Subdue Optimism (NewYork Times)
- Status update by Gesellschaft für Reaktorsicherheit (in German)