A March 12 explosion at the earthquake-damaged Fukushima Daiichi nuclear power plant in Okuma, Japan, appears to have caused a reactor meltdown.
The key piece of technology in a nuclear reactor is the control rods. Nuclear fuel generates neutrons; controlling the flow and production rate of these neutrons is what generates heat, and from the heat, electricity. Control rods absorb neutrons — the rods slide in and out of the fuel mass to regulate neutron emission, and with it, heat and electricity generation.
A meltdown occurs when the control rods fail to contain the neutron emission and the heat levels inside the reactor thus rise to a point that the fuel itself melts, generally temperatures in excess of 1,000 degrees Fahrenheit, causing uncontrolled radiation-
generating reactions and making approaching the reactor incredibly hazardous. A meltdown does not necessarily mean a nuclear disaster. As long as the reactor core, which is specifically designed to contain high levels of heat, pressure and radiation, remains intact, the melted fuel can be dealt with. If the core breaches but the containment facility built around the core remains intact, the melted fuel can still be dealt with — typically entombed within specialized concrete — but the cost and difficulty of such containment increases exponentially.(click here to enlarge image)
However, the earthquake in Japan, in addition to damaging the ability of the control rods to regulate the fuel — and the reactor’s coolant system — appears to have damaged the containment facility, and the explosion almost certainly did. There have been reports of “white smoke,” perhaps burning concrete, coming from the scene of the explosion, indicating a containment breach and the almost certain escape of significant amounts of radiation.
At this point, events in Japan bear many similarities to the 1986 Chernobyl disaster. Reports indicate that up to 1.5 meters (4.9 feet) of the reactor fuel was exposed. The reactor fuel appears to have at least partially melted, and the subsequent explosion has shattered the walls and roof of the containment vessel — and likely the remaining useful parts of the control and coolant systems.
(click here to enlarge image)
And so now the question is simple: Did the floor of the containment vessel crack? If not, the situation can still be salvaged by somehow re-containing the nuclear core. But if the floor has cracked, it is highly likely that the melting fuel will burn through the floor of the containment system and enter the ground. This has never happened before but has always been the nightmare scenario for a nuclear power event — in this scenario, containment goes from being merely dangerous, time consuming and expensive to nearly impossible.Radiation exposure for the average individual is 620 millirems per year, split about evenly between manmade and natural sources. The firefighters who served at the Chernobyl plant were exposed to between 80,000 and 1.6 million millirems. The Nuclear Regulatory Commission estimates that exposure to 375,000 to 500,000 millirems would be sufficient to cause death within three months for half of those exposed. A 30-kilometer-radius (19 miles) no-go zone remains at Chernobyl to this day. Japan’s troubled reactor site is about 300 kilometers from Tokyo.
The latest report from the damaged power plant indicated that exposure rates outside the plant were at about 620 millirems per hour, though it is not clear whether that report came before or after the reactor’s containment structure exploded.
A bit too soon to be making hay out of this trev. Though I do agree with your sentiments, there is a time and a place.
The problem with nuclear power is that IF something goes wrong it goes wrong big time.
In any event, where are we going to find the money for a nuclear plant, anyone priced one recently???
If New Zealand allowed it, a nuclear reactor would find funding. The question has always been about staying nuclear free and in my opinion now is the best time to discuss the issue. It’s really a no brainer if you ask me. They have just evacuated 300,000 in the North of Japan because of the Fukushima reactor 1 meltdown. Here’s what the Jackal has to say:
http://thejackalman.blogspot.com/2011/03/has-fukushima-killed-us.html
In light of recent events, I think there is more merit in shutting down all existing nuclear power plants instead of building more. There are clean tech alternatives that don’t put peoples lives at risk. Here’s a good place to get updates:
http://en.wikipedia.org/wiki/Fukushima_I_Nuclear_Power_Plant#cite_note-24
I’m with you Trev
We don’t need a bleepin nuclear disaster caused by an earthquake here!!!! 
I mean, we’re in the pacific ring of fire and have that creepy large fault line running through our country!
No nuclear nuttiness!
Relaying garbled first accounts gives a misleading impression.
Experts familiar with plant say the explosions are in the turbine hall not the reactor containment building. A byproduct of the boiling water type of reactor is hydrogen.
Of course the nuclear core itself still poses many dangers in this situation
We have 500 years of high quality coal which we are exporting for other countries to burn while the over-burdened poor of this country pay crippling power bills.
Nuclear power isn’t even that good at producing electricity. It makes waste that is impossible to dispose of. The danger of a meltdown (or unrequested fission surplus in euphemistic nuclear power speak) is obvious.
Build five giant hyperion coal power stations on the West Coast and solve our power problems as well as getting the West Coast working again. Buy back the lines and all other generation and put the power back into the hands of the people.
put the coal powered power stations in your own back yard mr plutonion.
build more hydro stations on the west coast, god knows we have enough water.
There is no evidence that this is another Chernobyl.
The reactor this time shut down instantly.
The electricity and its backup failed to run the cooling plant.
The explosion was not in the reactor.
The plant at Fukushima Daiichi was 40 years old and had had retrospective cooling added, but needed electricity to run it.
Wonder who wrote Trevor’s report above. There is a USA expert being quoted and he is anti-nuclear advocate which may colour his effort to connect this one with Chernobyl.
Personally I now think that Nuclear energy is the lesser evil in coping with the huge appetite for energy. The potential for loss of life through global warming, flooding, loss of food production, destruction most major cities etc is far greater than the risk from a modern nuclear plant.
Cost would be more likely to rule out nuclear power in NZ than safety concerns. In this case, a reactor built more than 40 years ago is experiencing pretty much a worst-case scenario in terms of earthquakes (8.9 quake, 10-meter tsunami) and may well come out of it OK. That means we could be extremely confident about anything built in the future in NZ to contemporary standards – but it isn’t likely to become an issue, because no-one here is likely to front up the cash for one.
You’re really stretching the violin strings there Trev. So you favour burning coal, some open cast mining and damming a few creeks to supply our power? You can’t have it both ways.
As well as the reactor 1 @ 460 MW, Fukushima 1 nuclear power plant Reactor 3 @ 784 MW is now without cooling. The explosion of unit 1 has released radiation into the atmosphere and sparked a mass evacuation.
You’re obviously stop personal abuse. Trevor
ghostwalker – the point is that some people are registering for radiation as they evacuate.
I’m a big fan of renewable geothermal – we have plenty and Mighty River Power are the world leaders. It provides great baseload, there is also lots of room for more wind farms. More work on hydrogen fuel cell batteries wouldn’t hurt either.
So not content with trying to make political capital of the most recent disaster, while Japan is on its knees searching for its missing, Trevor uses it to make another political point. Just despicable.
We have no need for nuclear, we have enough renewable energy to avoid it.
@Dominoes
Could you kindly inform us when opinions are permitted?
When you’ve done that, could you please inform politicians such as John Key, Judith Collins and the ACT Party conference? They’ve been making plenty of “political points”, and I’m sure this has deeply shocked you, and I’m sure you won’t hesitate to let them know of your “sincere” outrage.
Many thanks.
Matthew.Probably enough for us now but think globally.
What about waves generators?
If ever there was a reason to not use Nuke power – this would be it.
Its interesting that there are a handful that like to bleat on about not being political during a crisis. Get real – Rather than be a time to score political points, it is appropriate to hold others to account (like Lianne D in CHCH east who was doing her job) and when there is a disaster to highlight a problem to be aware of – like the risks of nuke power when a country is earthquake prone.
So, @Dom.. – please clarify what you mean by: ‘not content to make political capital in the last disaster etc’
How is highlighting this issue – which incidentally is huge for Japan and the rest of the pacific in terms of worst case scenario – being overly political? IMO, its timely to discuss the pros/cons.
@ ianmac (11:08) – Wouldn’t an increase of nuclear plants technically increase the risk of nuclear disaster type situations? And if things do go badly wrong, with radiation etc, its long term effects would be far more devastating I’d have thought than a flood or similar…
Yes! It is right of you to say this Trevor. The earthquake and tidal waves were absolute tragedies but the issue of nuclear stability is completely their own fault. The Japanese knowledgeably ran a terrible risk when they used nuclear power as does every nation who uses it, and they are now paying the price. This is a mistake which should silence any opposition to our nuclear free policy here at home, especially because of our recent ChCh quake.
The power plant itself may guarantee safety but the earth which it sits on can never guarantee that. And while we cannot predict when natural disasters occur, it is foolish to go about doing things pretending that one may never occur.
‘Rather than be a time to score political points, it is appropriate to hold others to account’
Well put Paul. The difference between this crisis and other recent ones is that this was 100% avoidable and decision based.
Solar, wind and tidal power for the win. We don’t need nuclear or coal to meet our power requirements.
@ spud… there is a wave power generating experiment goin gon off the coast of fremantle as we type.. (i worked on the construction). essentially it is just a giant box, with enough ballast in it so that it sits with the top just above the water.. the generators look like giant valve tappets which rock up and down when the waves wash through… they will run it for a few years, and if it works as efficiently as they hope, then the WA govt is going to build much bigger ones and anchor them along the coast… in theory they will be very efficient generators..
“Lets stay nuclear free” I wasn’t aware anyone who makes these decisions has suggested we shouldn’t or won’t??
@Dave – I think Trev just wants to make sure that it stays that way, what with Donnie Brash’s comments about gone by lunch time or something like that!
@bbfloyed – thanks.
Dave we do get overseas criticism for it. For example I remember Condoleezza Rice coming here and saying ‘if you really care about the environment you will get nuclear power’
Well, Don Brash is not a National MP, nor was that a recent comment, so it holds no water. Its about as valid as saying ‘a recent Labour Minister of Finance loves a flat tax policy’, although a good idea, its yesterdays news and comes across as a desperate attempt to gain traction with an electorate that is struggling to figure out what Labour stands for. Nuclear Free policies are entrenched in our DNA in New Zealand. I wouldn’t have thought they are even open for discussion.
I’d like to believe you, Dave, but many of Brash’s cronies are still in that party.
I will say that nuclear free is in most NZers DNA and many of those anti nukes are tories. 
By tories I mean free range, not NAT caucus! 
There is an excellent piece from a nuclear physicist friend of someone living in Japan which demonstrates that apart from the failure of the cooling pumping system, everything has worked as it should, and that the explosion has not caused any particular nuclear risk.
Most NZers would see “nuclear free” to mean free of nuclear weapons and perhaps nuclear powered vessels. Agreed. But not so sure that the peaceful use of nuclear is condemned in for instance medicine.
“… Nuclear Free policies are entrenched in our DNA in New Zealand…”
Just because a few trendy councils declared themselves nuke free luddites back in the the 80′s, with subsequent national legislation, doesn’t mean that all hold to that mantra. I firmly believe nuclear power generation has its place and New Zealand is not a better place for denying that opportunity.
Another Reactor Explosion/Meltdown
http://thejackalman.blogspot.com/2011/03/another-reactor-explosionmeltdown.html
Reports are that Unit 2 at Fukushima has exploded this morning at 6:14 AM Japan time. The New York Times reported today that the explosion appeared to be more severe than the previous detonations at the other reactors.
The problem Goff has in making decisions that suit the Labour Party over some left wing rival is that they campaign in the centre against National and left wing members see that as marginalising them within their own party. Whereas ACT is being protected in Epsom by National showing that it wants a to the right ally.
There is a place for a lefter wing party than Labour to mobilise those unhappy with more centrist policy platforms. The Greens have another focus and can and should not have that burden.
If my memory is correct I well remember many National Party MPs abusing Labour and the Left for demanding a nuclear Free NZ. The terrible events in Japan show we were right. I am proud to have been one of the Marchers in Hamilton with Trev the late Bill Dillon and the late Bob Reese and my Wife Gloria ,We were right then and now..
“If my memory is correct I well remember many National Party MPs abusing Labour and the Left for demanding a nuclear Free NZ. The terrible events in Japan show we were right. I am proud to have been one of the Marchers in Hamilton with Trev the late Bill Dillon and the late Bob Reese and my Wife Gloria ,We were right then and now..”
…and what’s more, we’re going to bring back that little man with the red flag who walks in front of every car warning the Luddites that progress is coming and they better watch out or they will disappear up the backside of a horse. We might also bring back sailing ships and cannon balls to halt this constant introduction of new technology which stops us from living in the past, unlike the proper John Marshall who always looked forward.
How many other countries went Nuclear Free after we declared ourselves Nuclear Free?