jacob300zx

Do you have an alternate definition for criticality cymx5?

Reverant

iTrader: (10)

Let's just hope we don't get to see a resonance cascade. The last time someone put some GG-3883 in the anti-mass spectrometer things went pretty bad really quick.

Bryce

iTrader: (24)

Resonance cascade scenario bad.

jacob300zx

http://uk.reuters.com/article/2011/0...7353Y820110406

(Reuters) - The core at Japan's Fukushima nuclear reactor has melted through the reactor pressure vessel, Democratic Congressman Edward Markey told a hearing on the nuclear disaster on Wednesday.

"I have been informed by the Nuclear Regulatory Commission that the core of Unit Two has gotten so hot that part of it has probably melted through the reactor pressure vessel," said Markey, a prominent nuclear critic in the House of Representatives.

rmcelwee

iTrader: (1)

NRC says not clear that Japan reactor has melted vessel


WASHINGTON (Reuters) - A top official from the U.S. Nuclear Regulatory Commission said on Wednesday it was not clear that Japan's Fukushima No. 2 nuclear reactor has melted through the reactor pressure vessel.

Earlier, Democratic lawmaker Edward Markey told a House of Representatives hearing on the nuclear disaster that the NRC had told him the core had melted through the vessel.

"That's not clear to us, nor is it clear to us that the reactor has penetrated the vessel," said Martin Virgilio, deputy executive director for reactor and preparedness programs at the NRC.

http://ca.news.yahoo.com/japan-no-2-...74109-708.html

olderguy

iTrader: (19)

If it melts through and continues through the earth, we cannot call it "The China Syndrome" 'cause it would end up in the South Atlantic Ocean. Maybe "The SAO Syndrome"


But then, the China Syndrome would need to start in Argentina.

http://www.freemaptools.com/tunnel-t...-the-earth.htm

Stein

iTrader: (46)

Stein

iTrader: (46)

New 7.4 quake today. They can't catch a break.

http://news.yahoo.com/s/ap/20110407/...pan_earthquake

jacob300zx

SCARY REPORT

https://docs.google.com/viewer?a=v&p...thkey=CJ3xiv8K

richyvrlimited

iTrader: (1)

What's scary in that report? I only scan read it, but it says noting really that the major news organisations haven't already said (abeit with a bit more detail).

Joe Perez

iTrader: (8)

I was kind of thinking the same thing. Granted the report is nearly two weeks old at this point, but it can basically be summarized as:

1. Some unknown level of damage is suspected to one or more levels of containment at all three units, however
2. The core is still contained within the reactor pressure vessel at all three units, although
3. The situation in several of the spent fuel pools is critical, and the release of some amount of particulate matter from these pools is likely.

The report makes several recommendations (water injection directly into RPV, restoration of nitrogen purge capability to displace oxygen and hydrogen, use of boron for neutron-capture, venting of containment to relieve pressure) all of which either have now been done or are actively being done.


I suppose that, as Obi-Wan said, it's mostly about your own point of view. A person who is predisposed to hysteria and doom-saying, or who is philosophically opposed to clean energy, might read that report as "scary."



A fine point, but I think accuracy is warranted here.

In a nuclear reactor, a moderator is something which encourages fission.

When a neutron is first emitted from the splitting of a uranium atom, that neutron has a very high kinetic energy and thus a very high velocity (thousands of km/sec), and is referred to as a "fast neutron."

Passing that neutron through a moderator (where it bounces around for a while, throwing off most of its energy) causes it to slow down and become a "thermal neutron." In this state, the probability of neutron capture (the neutron being absorbed by an atom of fissile material and causing it to split) is greatly increased.


Now, there are some reactor types (called fast reactors) which are designed to operate with unmoderated fast neutrons, however they are fairly uncommon and require some fairly exotic design elements. In a traditional thermal reactor, removing the moderator causes the chain reaction to stop, since the neutrons aren't being absorbed by the fuel and causing further fission events.

This is one of the passive safety features of BWR and PWR reactors- the moderator in these units is the same water that's cooling the core. So if that water starts to boil off, the power level of the reactor drops. The Chernobyl reactor was graphite-moderated, so as the coolant started to boil, the reactivity actually went up, and this is what caused the reactor to explode.


Getting back to boron, it is what they call a neutron poison. Boron does not moderate neutrons, it absorbs them completely, taking them out of the equation. In some older reactor designs, boric acid was used to fine-tune the power output of a reactor over the lifetime of a given fuel load (eg: when the fuel is fresh, a higher amount of boron will be circulated in the feedwater, and as the fuel ages, the level of boron present will be decreased in order to equalize reactivity.) Newer reactors (including those commonly in use for power-generation in the US and Japan) typically rely instead on core geometry, mostly by changing out only a fraction of the fuel load each refueling period, and moving fuel bundles around within the core to achieve a uniform reactivity spread.

Neutron poisons are also commonly used as one of the many emergency shutdown mechanisms in a reactor. During a SCRAM, large quantities of the material are injected under pressure into the core, to supplement the neutron-absorbing capabilities of the control rods.

Source for more info on both neutron energy states and neutron poisons: http://www.hss.energy.gov/nuclearsaf...19/h1019v2.pdf

Joe Perez

iTrader: (8)

Also, some non-scary data from the IAEA as of this morning (source http://iaea.org/newscenter/news/tsunamiupdate01.html):

On 6 April it was reported that the leakage of water from the sidewall of the pit closest to the sea has stopped after coagulation agents (liquid glass) were injected into the holes drilled around the pits.


According to the TEPCO Press Release of 4 April, approximately 10 000 T of water from the radioactive waste treatment plant and 1 500 T of subsurface waters stored in the sub drain pits of Unit 5 and 6 are being discharged to the sea to provide room to store water with higher levels of radioactivity in a safer manner. TEPCO has estimated that these discharges would increase the effective dose to a member of the public by 0.6 mSv, if he/she were to eat seaweed and seafood from 1 km from the discharge point every day for a year.

On average, a person living in the city of Denver, CO absorbs around 0.5 mSv annually in the form of cosmic radiation, and the average person in the US absorbs four times that amount (2.0 mSv) annually from ambient radon in the home. Source: http://www.epa.gov/rpdweb00/docs/402-k-07-006.pdf

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through the feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. Fresh water is being injected continuously into the RPVs through the fire extinguisher lines in Units 2 and 3 at indicated rates of 8 m3/h and 7 m3/h respectively using a temporary electric pump with off-site power.

On 6 April, low levels of deposition of both I-131 and Cs-137 were detected in 4 and 6 prefectures respectively. The values reported for I-131 ranged from 3.4 to 10 becquerels per square metre, for Cs-137 from 4.9 to 19 becquerels per square metre. Gamma dose rates continue decreasing. There is no significant change in gamma dose rates reported for 6 April compared to yesterday.

As of 5 April, I-131 and Cs-134/137 was detectable in drinking water in a small number of prefectures. All values were well below levels that would initiate recommendations for restrictions of drinking water. As of 6 April, one restriction for infants related to I-131 (100 Bq/l) is in place as a precautionary measure in only one village of the Fukushima prefecture.

jacob300zx

I have nothing against nuclear energy, I just wont down play this to the sheep. Here is a new one from thursday...100 sievert reading, could be higher but scale/measuring equipment only goes to 100. Just as a reference 6 sieverts is lethal.

http://blog.alexanderhiggins.com/201...ts-hour-15871/

copied from some guys blog due to him having reports from different sources all in one easy link for Joe.

Radiation levels At Japan Fukushima Nuclear Reactor 1 have spiked to 100 sieverts per hour following earthquake aftershock and tsunami. This is far above the 100% lethal dosage of 6 sieverts per hour.Radiation monitoring charts published by the Japanese government show that the radiation levels at Fukushima reactor number 1 have spiked to 100 sieverts per hour. It should be noted that it actual radiation could actually be higher because 100 sieverts per hour is the maximum that can be displayed on the chart.Exposure to this level of radiation will cause immediate death. According to the NIH radiation levels of 4 sieverts per hour will cause fatality in 50% of people and at 6 sieverts per hour death is almost certain. 100 sieverts per hour is far above the 100% lethal dosage amount of 6 sieverts per hour.

Joe Perez

iTrader: (8)

So, there's high radiation inside at the site of a damaged reactor, immediately following a magnitude 7.1 earthquake which stirred up all of the contaminated particulate material that's been settling out over the past month

Is this surprising?

jacob300zx

They just got hit with another quake today. It was a 6.6.

http://www.washingtonpost.com/world/...1ID_story.html

richyvrlimited

iTrader: (1)

7.1?

http://www.telegraph.co.uk/news/worl...ftershock.html

Joe Perez

iTrader: (8)

Initially rated at 7.1, revised to 6.6.

Sucks for them.

Expect another brief spike in radiation readings at locations inside the plant, as more dust and debris has been kicked up, followed by a gradual decline as they settle once again.

Offsite power at Fuku was lost, resulting in a loss of the water-injection pumps at units 1-3. Offsite power and pump operation were restored after approximately 50 minutes. That's pretty impressive. Overall, no new damage or change in status presently reported at Fuku- it's still stable.


Cleanup efforts are underway, as remotely-operated heavy equipment is being used to transport debris from units 1-4 to a common storage area.

jacob300zx

Evacuation radius is now going up to 30km.

jacob300zx

http://www.zerohedge.com/article/***...aximum-level-7

http://enenews.com/japan-officially-...yl-translation

http://www.disclose.tv/forum/fukushi...-7-t49011.html

NHK report
http://www3.nhk.or.jp/news/html/2011...249911000.html

Google translated
For a series of accidents happening at TEPCO’s Fukushima Daiichi Nuclear Power Station, Nuclear and Industrial Safety Agency of the Ministry of Economy, which released large amounts of radioactive substances that affect human health and the environment in a wide range As an assessment based on international standards of the accident, the worst “level seven” decided to raise. “Level 7″ is the same as the evaluation occurred in the Soviet Chernobyl disaster. Nuclear Safety Agency, 12, held a press conference with the Nuclear Safety Commission has decided to publish the contents of the evaluation. …


http://www.news.com.au/breaking-news...#ixzz1IIu2eU00

JAPAN’S unfolding nuclear disaster is “much bigger than Chernobyl” and could rewrite the international scale used to measure the severity of atomic accidents, a Russian expert says.

“Chernobyl was a dirty bomb explosion. The next dirty bomb is Fukushima and it will cost much more” in economic and human terms, Natalia Mironova said.

Ms Mironova is thermodynamic engineer who became a leading anti-nuclear activist in Russia in the wake of the accident at the Soviet-built reactor in Ukraine in 1986.

“Fukushima is much bigger than Chernobyl,” she said, adding that the Japanese nuclear crisis was likely to eclipse Chernobyl on the seven-point international scale used to rate nuclear disasters. …

“Chernobyl was level seven and it had only one reactor and lasted only two weeks. We have now three weeks (at Fukushima) and we have four reactors which we know are in very dangerous situations,” she said. …

jacob300zx

Fire at the number 4 reactor.

From Reuters: "A fire broke out at Japan's crippled Fukushima Daiichi nuclear power plant, operator Tokyo Electric and Power (TEPCO) said on Tuesday, although flames and smoke were no longer visible. A worker saw fire at a building near the No.4 reactor at around 6:38 a.m. (21:38 GMT) and a fire fighting unit of the Self Defence Forces was sent to fight the blaze, a TEPCO spokesman said. "Flames and smoke are no longer visible but we are awaiting further details regarding whether the fire has been extinguished completely," he said. Japan has been battling to bring under control the plant damaged severely by last month's devastating earthquake and tsunami."