There have been further developments at Fukushima overnight that have, according to the IAEA, made the situation ‘reasonably stable‘ (although it is still serious). Given the state of play over the last week, I’ll take any positive sign I can get.

Other points to note, as of the morning of Friday 18 March:

1. FEPC says the following:

Through visual surveys from the helicopter flying above the Unit 4 reactor secondary containment building on March 16, it was observed that water remained in the spent fuel pool. The helicopter was measuring radiation levels above Unit 4 reactor secondary containment building in preparation for water drops. This report has not been officially confirmed.

2. WNN says:

The Ministry of Economy Trade and Industry said at 8.38pm that a cable was being laid to bring external power from transmission lines owned by Tohoku Electric Power Company. This was to be connected when radiation levels had died down after a planned venting operation at unit 2. In addition, one of the emergency diesel units can now be operated and will be used to supply unit 5 and 6 alternately to inject water to their used fuel pools. Later, the power will be used to top up water in the reactor vessels… After clearing heavy explosion debris from tsunami and the various explosions across the site over the last six days, eleven high pressure fire trucks showered unit 3. World Nuclear News understands that 30 tonnes of water “was delivered” in an attempt to shoot water through the holes in the side of the building, which appear to be very close to the fuel ponds themselves… Despite high levels of radiation close to the units, levels detected at the edge of the power plant site have been steadily decreasing [the below is given in reverse chronological order]. 17 March, 4.00pm: 0.64 millisieverts per hour 17 March, 9.00am: 1.47 millisieverts per hour 16 March, 7.00pm: 1.93 millisieverts per hour 16 March, 12.30pm: 3.39 millisieverts per hour

3. The two statements above are supported by the updates from the NEI:

In Japan, engineers have laid a power line that can connect reactor 2 of the Daiichi facility to the off-site power grid, the International Atomic Energy Agency reported. Workers are working to reconnect the power to reactor 2 after they complete spraying water into the reactor 3 complex to provide additional cooling to the used fuel pool. Reconnecting to the power grid is expected to enhance efforts to prevent further damage at the plant. Japan’s Nuclear and Industrial Safety Agency reported on Thursday that the backup diesel generator for reactor 6 is working and supplying electricity to reactors 5 and 6. TEPCO is preparing to add water to the storage pools that house used nuclear fuel rods at those two reactors. Radiation readings at the Fukushima Daiichi site boundary were measured today at a lower level, between 2 and 3 millirem per hour. Fukushima Daiichi site status The reactors at the Fukushima Daiichi plant are in stable condition and are being cooled with seawater, but workers at the plant continue efforts to add cooling water to fuel pools at reactors 3 and 4. The status of the reactors at the site is as follows: Reactor 1’s primary containment is believed to be intact and the reactor is in a stable condition. Seawater injection into the reactor is continuing. Reactor 2 is in stable condition with seawater injection continuing. The reactor’s primary containment may not have been breached, Tokyo Electric Power Co. and World Association of Nuclear Operators officials said on Thursday. Containment pressure is at 65 psig, an indication that containment has not been breached. Access problems at the site have delayed connection of a temporary cable to restore offsite electricity. The connection will provide power to the control rod drive pump, instrumentation, batteries, and power to the control room. Power has not been available at the site since the earthquake on March 11. Reactor 3 is in stable condition with seawater injection continuing. The primary containment is believed to be intact. Pressure in the containment has fluctuated due to venting of the reactor containment structure, but has been as high as 83 psig. TEPCO officials say that although one side of the concrete wall of the fuel pool structure has collapsed, the steel liner of the pool remains intact, based on aerial photos of the reactor taken on March 17. The pool still has water providing some cooling for the fuel, however helicopters dropped water on the reactor four times during the morning (Japan time) on March 17. Water also was sprayed at reactor 4 using high pressure water cannons. Reactors 5 and 6 were both shut down before the quake occurred. Primary and secondary containments are intact at both reactors. Temperature instruments in the spent fuel pools at reactors 5 and 6 are operational, and temperatures are being maintained at about 62 degrees Celsius. TEPCO is continuing efforts to restore power at reactor 5.

If all of this is successful, the plant will be able to take over from the workers in cooling the fuel in the reactor.

I’ll provide a further update at the end of today. Meanwhile, you can track the comments on this post (Note: I suggest we switch to this thread for the rest of today), which are once again doing a great job at providing a minute-by-minute feed of the latest developments.

Below I reproduce a short essay by Ted Rockwell. Dr Rockwell is a member of the National Academy of Engineering. His classical 1956 handbook, The Reactor Shielding Design Manual, was recently made available on-line and as a DVD, by the U.S. Department of Energy. Back in 2002 he was co-author on an article in Science journal, “Nuclear Power Plants and Their Fuel as Terrorist Targets“. It’s definitely worth reading as it’s highly relevant to the current situation — if you bear in mind that the ‘terrorist’ in this context was Mother Nature — and a brutal one at that.

Ted’s short essay (Rod Adams has also reproduced this), given below, explains well what I meant by my earlier statement:

What has this earthquake taught us? That it’s much, much riskier to choose to live next to the ocean than it is to live next to a nuclear power station.

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Fukushima: it’s not about radiation, it’s about tsunamis

A lot of wrong lessons are being pushed on us, about the tragedy now unfolding in Japan. All the scare-talk about radiation is irrelevant. There will be no radiation public health catastrophe, regardless of how much reactor melting may occur. Radiation? Yes. Catastrophe? No.

Life evolved on, and adapted to, a much more radioactive planet, Our current natural radiation levels—worldwide—are below optimum. Statements that there is no safe level of radiation are an affront to science and to common sense. The radiation situation should be no worse than from the Three Mile Island (TMI) incident, where ten to twenty tons of the nuclear reactor melted down, slumped to the bottom of the reactor vessel, and initiated the dreaded China Syndrome, where the reactor core melts and burns its way into the earth. On the computers and movie screens of people who make a living “predicting” disasters, TMI is an unprecedented catastrophe. In the real world, the molten mass froze when it hit the colder reactor vessel, and stopped its downward journey at five-eights of an inch through the five-inch thick vessel wall.

And there was no harm to people or the environment. None.

Yet in Japan, you have radiation zealots threatening to order people out of their homes, to wander, homeless and panic-stricken, through the battered countryside, to do what? All to avoid a radiation dose lower than what they would get from a ski trip.

The important point for nuclear power is that some of the nuclear plants were swept with a wall of seawater that may have instantly converted a multi-billion dollar asset into a multi-billion dollar problem. That’s bad news. But it’s not unique to nuclear power. If Fukushima were a computer chip factory, would we consider abandoning the electronic industry because it was not tsunami-proof? It would be ironic if American nuclear power were phased out as unsafe, without having ever killed or injured a single member of the public, to be replaced by coal, gas and oil, proven killers of tens of thousands each year.

Moreover, the extent and nature of the damage from seawater may be less than first implied. Rod Adams, a former nuclear submarine officer, who operated a nuclear power plant at sea for many years, says that inadvertent flooding of certain equipment with seawater was not uncommon. He includes electronics-laden missile tubes. “We flushed them out with fresh water,” he said. “Sometimes we had to replace insulation and other parts. But we could ultimately bring them back on line, working satisfactorily.”

The lessons from Japan involve tsunamis, not radiation.

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Footnote — Some additional comments from Ted Rockwell, by email correspondence:

I must admit that our Science articles did not give much attention attention to the small-volume containment plants, and we should do so after the information on Fukushima has come in. Our focus was on getting past the proving that scenarios that led to intolerable situations were tolerably improbable. This traditional approach is an essential but not sufficient part of plant design.

My approach was to come in from the other side: To assume that the worst situation was one that led to some molten fuel, coupled with loss of containment integrity, and ask: what then? Does radioactivity get out in great enough quantities, into enough lungs? That’s essentially the TMI situation, and I concluded that it led to the TMI outcome: a disaster for the plant owner, but a wholly tolerable situation radiologically. We’re going to have to go back and apply a wider range of conditions to that analysis.

But radiation must still be treated like any other variable, and not the ultimate injury. It should not outrank death by inhalation of coal particles, for example. The obsessive fascination with radiation as the worst possible danger leads to mass evacuation as the most conservative response. I don’t know any experienced disaster manager who agrees that mass evacuation is always a conservative response.