mike23thurgood comments

No one surely has a right to claim that any houses were destroyed by any of the hydrogen explosions and fires in the cores of the Fukushima Daiichi nuclear reactors, and one fuel pond. The massive destruction was caused by the huge 15 to 16 metre tsunami. I watched shots on TV of its inexorable destructive advance through village and town streets.

Of course there has been a release of fission product radioactivity from the Daiichi nuclear reactors, which has caused contamination over an area within, I believe, a 20 km radius of the nuclear plants.

It is usually the more high-temperature volatile radioactive and soluble fission products which tend to become distributed, the former through the air. I am not aware that there's been any loss into the environment of actual transuranic elements, including uranium itself or MOX fuel uranium and plutonium, because none of them are volatile. Therefore what radioactivity has been released into the environment may possibly last for about 100 years, decaying continuously throughout that period, of course. It certainly won't stay around for millions of years. Well, the only radioactivity likely to be present which stays around for that length of time will already have been there for millions of years, such as natural uranium and possibly natural thorium.

It is so easy to forget that the human environment right across the world has been permanently radioactive at an extremely low level throughout the 2 billions of years or so through which evolution has been so successful (plus all those naturally occurring ionizing radiations).

The safety of nuclear reactors is being further enhanced as a result of the lessons learned from Fukushima, but not only from tsunamis, which mainly arise through earthquake events around the Pacific seaboard. Thus there's the potential for aircraft crashes, deliberate or otherwise, into containment buildings. The idea of terrorist attacks is a macabre scenario, of course, but if terrorists wish to make the earth uninhabitable for everyone, including themselves, then the state of their minds should be highly suspect.

Nothing I have written negates in any way the rights of anyone from wishing to comment against nuclear power, but please do so with a knowledge of the facts, not in ignorance of them. We don't necessarily have to emulate Greenpeace!

I'm sure it had to come some day. However, it's really coffee flavoured chocolate.

I'll be looking out for it in our smart food shops in Cape Town. However, I know only too well that I will have one Hecuba of a problem convincing my wife to even look at it, yet alone buy one!

I don't see why Yoko Ono is being criticised for suggesting geothermal power as a possible source of energy across Japan. She might not be a vulcanologist, but no doubt in her travelings she has seen geothermal power stations.

However, most volcanic activity affecting Japan is due to subducting events because the Pacific Ocean is contracting, whereas volcanoes around the Atlantic Ocean occur where the earth's crust is expanding, and therefore producing cracks through which very hot magma from the earth's core flows up. Which type of area would provide the most stable environment for geothermal power stations is an important factor to be considered. You don't want your geothermal generating plants to be continually destroyed by tectonic plate movements.

Now, I am no geologist or vulcanologist, far from it, but surely it is worth such specialists investigating the possibilities?

The only pollutant to be dealt with would be sulphur dioxide and carbon dioxide, both of which are likely to be released into the atmosphere in any case. There may be some radioactive Nobel gases, which can generally be released into the atmosphere, being both rapidly diluted to extremely low concentrations and relatively rapidly disappearing altogether due to their short half lives. But, again, they are released into the atmosphere, naturally, and we don't hear complaints of excessive radiation exposure to such gases near active volcanoes. Being emitted into the atmosphere at high temperature, they rise up high into the atmosphere.

Some respondents believe that the IAEA considers that there could be a repeat of the Fukushima Daiichi incident in wanting more involvement in such incidents.

It wasn't the IAEA who initiated the thoughts about a more positive involvement in nuclear incidents on a hindsight basis, but the nuclear authorities in other countries affiliated to the IAEA indicated their concern. All affiliated countries have to agree on what they want to see the IAEA doing. It costs!

A more positive intervention of the IAEA in nuclear incidents has been raised as a general point, not on the basis that Fukushima could ever occur again. There might possibly be another magnitude 9 offshore earthquake off Japan in the future, with an equally huge tsunami, but by then I am sure that Japan will have long implemented all the necessary precautions to guard against a repeat problem at any of its nuclear reactors.

Necessary safety precautions had already been achieved for the Japanese nuclear reactors to withstand such a high magnitude earthquake (some distance offshore, of course), and but for the tsunami there would have been no disastrous consequences as did occur at the Daiichi nuclear power station, and for no other reason than power supplies were cut off, with far too long an interval before they could be restored.

Writing from South Africa, I trust that Japan is progressing well with its recovery from the most terrible disaster of the huge tsunami on its affected population. As with millions of other people in the world, I have never been a victim of any earthquake, so fully appreciating the real trauma as it affects large numbers of people, personally, isn't easy.

At one point in his article, Lucas W Hixson says this: "For example: despite the catastrophic overall failure of the Monju Fast Breeder Reactor in Japan, efforts to expand nuclear power production have increased despite the glaring limit of fuel supply, which is expected to run out within one hundred fifty years".

Now, quite apart from the Monju FBR's problems, FBRs are a fuel breeder type of reactor. Therefore it can convert uranium-238 to useful fissile fuel. It can do the same using thorium-232 (producing the fissile U-232), of which there is a lot more occurring naturally than natural uranium.

Where I am concerned, this comment unfortunately devalues the credibility of the author's arguments, especially as elsewhere he writes about people making comments where nuclear power is concerned when they know little or nothing about it. Well, for the author to limit his thoughts merely to the amount of fissile uranium-235 remaining for only about another 150 years of reactor operations is clearly quite incorrect. Used to maximum efficiency in FBRs, it could last for about - an absolutely awful guess of, say, 1 000 years. But to do so, fast breeder reactors will be essential. But they will have to work with no disasters, except for the once in 10 000 years probability design criterion.

It's no way an easy situation for anyone to appreciate. A major problem is measuring radioactivity over a large area of land - just imagine the problem, how many people do you need on the job, and how many radiation monitors are available. Checking every square metre over many tens of square kilometres of area.

The depositing of dust or other particulate contamination from the air is notorious for not behaving according to one's perception of a uniform deposition. No, it's very erratic. Hopefully any areas beyond the 20 km exclusion zone will only have very light contamination, if any at all.

Is any further airborne particulate radioactive contamination arising from the three damaged Dai-Ichi units and the fuel pool of unit 4? Only TEPCO can answer that question, but I haven't come across any recent statements about it in their frequent news releases. The lower TEPCO can keep the temperature of the fuel down so will less airborne contamination arise, or none at all.

Parents can only hope that the personal dosimeters which are being, or already have been, issued to children will show only very minimal exposure above the natural ionizing radiation background. No one can be sure until the first results of processing the personal dosimeters become available.

Xinef said this:

Right, then from the point of view of an informed person your statement sounds more than stupid. Pumping equipment (among other things) would then become radioactive as well, which, believe it or not, is a problem. Thank you for insulting the people working on this, now go with your great legs and operate radioactive equipment yourself.

Now I obviously haven't seen details of how the plant works. It has filters to remove radioactive particulates, but what system dos it have to remove radioactivity in solution? If there's some system to remove these, that solves the problem of the system not becoming contaminated in any case. However, obviously the ~100 000 tons of water has got to be removed to allow access to the structure for whatever remedial actions can be carried out at this stage.

But once ll this lot has been finally pumped out, is there any real reason why the filtered decontaminated water can't be recirculated, even if it has a residual amount of radioactive solubles in it? I/m asking the question from the practicality of doing this, because everything is high;y contaminated with fission products in any case. Of course the water pumping plant still has to be accessible for maintenance, and filter replacements, so it can't be allowed to become too highly contaminated, resulting is unacceptably high radiation doses to workers.

But on the other hand, unless the decontaminated water is released to the sea - obviously yes if it's seawater to start with - the sea is a pretty large diluting medium. Freshwater supplies certainly must not be contaminated with it.

Just wondering, because 100 000 tons of water is around 100 000 cubic metres of it - quite a large volume to deal with.