News Japan Earthquake, Tsunami, & Nuclear Disaster

[Belisarius]

Every scrap of good news is a little comfort in this terrible situation

Meanwhile from BBC, reporting a tweet
0837: Noriyuki Shikata, from the Japanese PM's office tweets: "Intentional venting of the air was carried out for Unit 3 of Fukushima Plant I as well to lower the pressure inside the containment vessel"

The no.3 reactor is going through exactly the same process as the no. 1, 24 hours before.
Are there any technical implications in the fact that it uses MOX fuel, apart from the higher toxicity of the plutonium?
What I mean is, is the process more or less stable than the no. 1 plant?

 

[N_Molson]

Japan prime minister just gave an emotional speech, in which he was saying "it was to worst hardship for Japan since WWII".

 

[IronRain]

CNN reports that they're pumping sea water into reactor No 3

 

[N_Molson]

BBC :

1105: Yukio Edano, the government spokesman, is speaking now. He says authorities have begun injecting seawater at the No 3 reactor at Fukushima 1 power station. He said the water level is thought to be rising, but the gauge, which seems to be broken, is not showing this.

1107: Govt spokesman: Currently radiation monitor hasn't show any change.

1008: Govt spokesman: Trying to lower pressure at No 3 reactor at Fukushima 1 power station. Confirms risk of explosion.

 

[Wishbone]

Re: water gauge. We should (worst-case) assume the gauge is correct, and the water doesn't get into the RPV.

Re: MOX. TBH, I don't know (never been a fan of Pu chemistry). The chemical composition may affect the meltdown timeline as well as reactions with seawater.

 

[MeDiCS]

http://www.guardian.co.uk/world/2011/mar/13/japan-second-nuclear-reactor-threat-fukushima

"Plutonium MOX fuel increases the risk of nuclear accident due the neutronic effects of plutonium on the reactor," Burnie told the Guardian. "In the event of an accident – in particular loss of coolant – the reactor core is more difficult to control due to both neutronics and higher risk of fuel cladding failure.

"In the event of the fuel melting and the release of plutonium fuel into the environment, the health hazards are greater, including higher levels of latent cancer."

 

[Wishbone]

http://www.nrc.gov/reading-rm/doc-collections/news/2011/11-045.pdf

March 12, 2011:

Two officials from the U.S. Nuclear Regulatory Commission with expertise in boiling water nuclear reactors have deployed to Japan...

 

[Urwumpe]

Nuclear powered submarines would provide another means of providing portable power for the reactor cooling systems. The American Seawolf submarine uses 40 megawatt reactors and the Russian Akula class submarines operate at 190 megawatts.
There would be less concern for tsunamis for submarines if operated off shore. You would still need likely to be hundreds of yards off shore for their required depth to operate. Then you would also need sufficient cabling to cover that distance.

Well, a few kilometers would be better if you remember how far the water retreats, so the cable length and other factors could sure mean that this solution is not feasible at all. It would likely risk the safety of another nuclear reactor.

Much better and more reliable would be simply being able to plug emergency power from a fire truck or other normal land based emergency forces into any nuclear reactor cooling system. The problem is not having enough power available for pumping only 875 liters of water every second (one bath tub per second), the problem is just connecting it into the system.

There is no external emergency power plug at the building for connecting quickly external power into the system, you need to connect from the failed emergency diesel generators by modifying the cabling a bit. A hack, if you want to call it that way.

--------

There are also ten German Pipe QA experts of the company Areva working at Unit 3 currently, according to Spiegel Online.

Current situation: Pressure can't be controlled, relief valve is defect, coolant level can't be measured. compared to Unit 1, a much more dangerous situation, which still had relief valves and coolant level monitoring working.

 

[Dambuster]

What is the worst case scenario for reactor 3?

 

[IronRain]

The Onagawa nuclear powerplant has gone bad too. It still the lowest warning that is possible but still they're worried about it

 

[Urwumpe]

What is the worst case scenario for reactor 3?

Since the coolant level can't be monitored, you can only carefully inject water and boron acid. also the use of MOX fuel is very dangerous in that context, since MOX fuel cools down slower than normal Uranium fuel and has a higher risk of recriticality.

The worst case would be a massive failure of the pressure vessel during a recriticality event. This would not just spew out the normal fuel element and isotopes, but also maximal 6% Plutonium, which is very ugly.

The containment of such reactors has a smaller volume as for example the sphere shaped containments of German reactors, or the Mark III can shape, that most modern reactors in the USA or France use. If you have enough water there to turn rapidly into steam, this containment can fail as well at its weaknesses.

A hydrogen explosion would delay rescue operations there, but it is really no risk to the reactor as long as it happens outside the pressure vessel. Even an explosion in the suppression pool below the reactor would be tolerable. It is much better, should it happen outside the containment, like in Unit 1. Ideal would be no hydrogen explosion though.

But:My personal bet about how things will turn out, is that the technicians are all lucky, and also have the wisdom to tell how much water and boron acid they can inject there safely despite having no indication of the coolant level. I really don't want their job now.

The reactor will be a complete loss anyway now. Once you have large amounts of hydrogen forming in a reactor, you are already have many damaged fuel elements that release radioactive gases and fuel fragments.

Small amounts of damaged fuel elements are bad, but happen pretty often in nuclear reactors, as far as I can tell from following German accident reports. small damages mean that you can still remove the damaged fuel elements during maintenance. Large damages to the cladding on the other hand mean that it is impossible to refuel and repair the reactor core again.

 

[Belisarius]

From BBC live log

1541: A former nuclear power plant designer has said Japan is facing an extremely grave crisis and called on the government to release more information, which he said was being suppressed. Masashi Goto told a news conference in Tokyo that one of the reactors at the Fukushima-Daiichi plant was "highly unstable", and that if there was a meltdown the "consequences would be tremendous". He said such an event might be very likely indeed. So far, the government has said a meltdown would not lead to a sizeable leak of radioactive materials.
1548: Mr Goto said the reactors at the Fukushima-Daiichi nuclear plant were suffering pressure build-ups way beyond that for which they were designed. There was a severe risk of an explosion, with radioactive material being strewn over a very wide area - beyond the 20km evacuation zone set up by the authorities - he added. Mr Goto calculated that because Reactor No 3 at Fukushima-Daiichi - where pressure is rising and there is a risk of an explosion - used a type of fuel known as Mox, a mixture of plutonium oxide and uranium oxide, the radioactive fallout from any meltdown might be twice as bad.
1553: He accused the government of deliberately withholding vital information that would allow outside experts help solve the problems. "For example, there has not been enough information about the hydrogen being vented. We don't know how much was vented and how radioactive it was." He also described the use of sea water to cool the cores of the reactors at Fukushima-Daiichi as highly unusual and dangerous.
1558: He described the worst-case scenario: "It is difficult to say, but that would be a core meltdown. If the rods fall and mix with water, the result would be an explosion of solid material like a volcano spreading radioactive material. Steam or a hydrogen explosion caused by the mix would spread radioactive waste more than 50km. Also, this would be multiplied. There are many reactors in the area so there would be many Chernobyls."

1600: At the same time, Malcolm Crick, the secretary of the UN Scientific Committee on the Effects of Atomic Radiation, has told the Reuters news agency: "This is not a serious public health issue at the moment. It won't be anything like Chernobyl. There the reactor was operating at full power when it exploded and it had no containment."

This second quote makes no sense to me. What does he mean it had no containment?

EDIT: OK I understand, checked Chernobyl on Wiki

The burning graphite moderator increased the emission of radioactive particles, carried by the smoke, as the reactor had not been contained by any kind of hard containment vessel (unlike all Western plants).

There are definitely two differing versions of the risk levels involved here.

 

[Urwumpe]

This second quote makes no sense to me. What does he mean it had no containment?

There are definitely two differing versions of the risk levels involved here.

It means Mr Crick has no clue what a containment structure actually is and what a nuclear accident can mean in all its variations.

Chernobyl was actually operating at minimal power before a uncontrolled power excursion drove it beyond maximal power. Won't happen here for sure, even a recriticality event won't reach such power levels.

Also Chernobyl and similar reactors had a pretty well designed containment despite its demise. The problem was that it was not enough for this kind of accident. There had been many biological shields, many layers of water and sand and concrete around it. But 1000 tons of containment cover above the reactor is nothing of worth, if you have a few Gigawatts of nuclear power below it. also the cover was having many intentional weaknesses for being able to swap fuel elements during operation of the reactor for producing plutonium faster. But this weakness was no problem in Chernobyl, the many holes and valves and doors there has been removed as whole from the reactor.

Also, the RBMK reactors are likely the best researched ones in the world now, because of this event... Ignalina had a lot of technical documentation on their homepage describing any detail of the reactor.

 

[Belisarius]

I find the complacency of those in supposedly responsible positions in the UN, and some senior academics, quite disturbing.

Can't find any background on Mr Goto - anyone know who he is?

 

[Urwumpe]

Can't tell anything there about him. But his arguments are correct. Just a bit alarmist, which is not really wise, if there is already an alarm running.

 

[Belisarius]

Any kind of overhead imagery?

NASA's site has some sat images but nothing related to the nuclear stations.

http://www.nasa.gov/topics/earth/features/japanquake/index.html

 

[N_Molson]

BBC News :

1706: The news about Tokai comes as the authorities battle to prevent a meltdown at the stricken Fukushima-Daiichi complex. Sea water is being pumped into three overheating reactors there. The plant was rocked by an explosion on Saturday, which blew off the roof of one reactor building. Meanwhile, a state of emergency has been declared at a second nuclear site. The International Atomic Energy Agency said increased levels of radiation had been detected at Onagawa, close to the area worst hit by the tsunami.

 

[Belisarius]

So now we have the 5 reactors in emergency condition mentioned yesterday but not named:
Fukushima Daiichi 1 2 and 3
Tokai (120km north of Tokyo)
and Onagawa (approx 200km north of Fukushima)

Does that seem like a correct summation of the stations at risk?

 

[PennyBlack]

This isn't a bad link for updates on the reactors...

http://www.bbc.co.uk/news/world-middle-east-12307698

http://www.bbc.co.uk/news/world-asia-pacific-12711226

 

[Belisarius]

Just reported on Al-Jazeera English

http://www.youtube.com/user/aljazeeraenglish?blend=1&ob=4

"The whole island of Honshu was shifted 2.4 metres to the west by the quake on Friday."

No source given. If true, this would be a very dramatic demonstration of the seismic shift involved.