Having just watched "Nuclear Nightmare: Japan In Crisis" with Paula Zahn, I must say that Paula Zahn and the Discovery Channel got it pretty much right.
The Richter 9 earthquake, and the 47 foot tsunami after it, resulted in unbelievable damage to the Fukushima nuclear plants (all six of them).
Fukushima was designed for a 7.9 earthquake and a 30 foot tsunami.
The worst result was at plant four. The spent nuclear fuel in plant 4 was safe - until the water in the pool either splashed out drained out through a crack. The fuel overheated, reacted with the steam, and created hydrogen. The hydrogen exploded on day four - at dawn on March 15. But guess what? The hydrogen was inside the partially melted nuclear fuel. The explosion sprays nuclear material into the air, causing a "radiation spike" and the majority of the radioactive material release.
Or maybe not. Plant two found a radioactive water release, which was not stopped until April 5. But this plant's containment was suspected to be damaged on March 15 - and the water release probably started as soon as the damage occurred.
Worse, and a surprise to many in the nuclear community - the plant 2 containment was probably damaged and cracked on day 1. Either the earthquake shock wave cracked the suppression pool, called a torus, or the tsunami bent the entire nuclear plant on it's foundation, which cracked the torus.
And the massive radioactive release began on day 1. Day 1, when the fuel had not had time to decay to anything anywhere near safe levels.
This is my conclusion, for whatever it is worth.
And it is the best way I know to explain how the release could be 1/10 of what Chernobyl released. (Al though I believe the release was way below that.)
We won't know for sure for six months or more, when humans can examine the plants carefully.
Friday, April 29, 2011
Japan's Nuclear Nightmare
In spite of a dearth of information, here is how I see the Japanese nuclear situation.
When the U.S. DOE provided maps of the nuclear contamination http://blog.energy.gov/content/situation-japan I calculated the total release, getting 5.9 million curies (5,900,000). That is about 1/10 what Chernobyl released.
But, I found an error in my calculations - I had assumed point sources beneath the radiation detectors. Actually each detector received radiation from directly below it, and from the areas nearby, and from everywhere out to the horizon. When I calculated assuming a spread-out source, I got just 15,000 curies released. Which one is more accurate? That depends on how the U.S. DOE did it's calculations.
The DOE maps do not show what they detected - the airplanes flew several hundred feet up, and detected radiation at that level. They then put out maps showing how bad it is at knee high (one meter). Unless I can see how they re-calculated to get what they reported, I cannot be sure how accurate my calculations are.
Before I could get someone to check my modelling and my math, Japan's nuclear safety agency reported that the total release was 5,000,000 curies, or 1/10 of what Chernobyl released (check this, http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1304052023P.pdf , second page, red line near the bottom).
I was so disheartened that I made no new blog entries for 26 days.
BUT ... Japan also reports that the maximum dose to infant's thyroids will be less than 50 Rem. That is consistent with 15,000 curies, not with 5,000,000 curies.
Did Japan's nuclear safety agency make the same mistake that I made? Are they now afraid to correct their published error? I hope so.
All the information I have says, the release was less than 150,000 curies.
A nightmare; a disaster; but not a Chernobyl and not a catastrophe.
Not enough to cause more than about 40 deaths to members of the public.
The Fukushima 50 are a different matter. Their doses are quite high; they may have sacrificed their health, or even their lives, to keep the rest of us safe. May God bless them and keep them - and theirs.
When the U.S. DOE provided maps of the nuclear contamination http://blog.energy.gov/content/situation-japan I calculated the total release, getting 5.9 million curies (5,900,000). That is about 1/10 what Chernobyl released.
But, I found an error in my calculations - I had assumed point sources beneath the radiation detectors. Actually each detector received radiation from directly below it, and from the areas nearby, and from everywhere out to the horizon. When I calculated assuming a spread-out source, I got just 15,000 curies released. Which one is more accurate? That depends on how the U.S. DOE did it's calculations.
The DOE maps do not show what they detected - the airplanes flew several hundred feet up, and detected radiation at that level. They then put out maps showing how bad it is at knee high (one meter). Unless I can see how they re-calculated to get what they reported, I cannot be sure how accurate my calculations are.
Before I could get someone to check my modelling and my math, Japan's nuclear safety agency reported that the total release was 5,000,000 curies, or 1/10 of what Chernobyl released (check this, http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1304052023P.pdf , second page, red line near the bottom).
I was so disheartened that I made no new blog entries for 26 days.
BUT ... Japan also reports that the maximum dose to infant's thyroids will be less than 50 Rem. That is consistent with 15,000 curies, not with 5,000,000 curies.
Did Japan's nuclear safety agency make the same mistake that I made? Are they now afraid to correct their published error? I hope so.
All the information I have says, the release was less than 150,000 curies.
A nightmare; a disaster; but not a Chernobyl and not a catastrophe.
Not enough to cause more than about 40 deaths to members of the public.
The Fukushima 50 are a different matter. Their doses are quite high; they may have sacrificed their health, or even their lives, to keep the rest of us safe. May God bless them and keep them - and theirs.
Sunday, April 3, 2011
Bad but not a Catastrophe
The Fukushima Fifty operators believe they may die from radiation exposure. Pray for them, and thank God for keeping them loyally on the job. Their efforts have kept the disaster from growing to a catastrophe.
And, child doses, even to the thyroid, is minimal. 900 infants were tested and are OK. My apology for optimism below, may have been premature. http://www.jaif.or.jp/english/aij/member/2011/earthquakereport41.pdf
The United States Department of Energy has flown over the Fukushima area and recorded the radiation. http://blog.energy.gov/content/situation-japan
Maximum doses outside the plant are less than 0.03 Rem per hour. That means 100 hours would get people 3 Rem, or 1000 hours would give 30 Rem.
30 Rem is where doctor's can test the blood, and find minor changes. Below that level, there are no short-term effects.
The radiation has dropped by a factor of ten in two days. Unless something major happens, the people will not ... repeat, not, get more that 30 Rem. No short-term effects.
That leaves cancer and other major illnesses.
The total release cannot be accurately estimated - yet. Japan and the utility, TEPCO, have not released enough information.
Nuclear reactors have several layers of defense against a release. The innermost one is the fuel itself. It is hard to melt this ceramic fuel. Second is a primary cooling system, with steel walls. Third that is a containment building, with steel lining and reinforced concrete strength. Fourth is a reactor building, which protects the containment.
But, the fuel and primary coolant system of three plants (1,2,3) are severely damaged or melted (and re-frozen). The containments of all three are functional, although one is damaged. Radiation within the fuel has decayed so much that it is highly unlikely that any containment will be further damaged. This means that the reactor fuel will stay in the reactors - all but about 1 percent, which has already been released. Plants one and three had hydrogen explosions outside the containment, but inside the reactor building.
And, the fuel in one spent nuclear fuel pool - for unit 4 - has been damaged and probably melted. This is the unit which had a hydrogen explosion, and it apparently happened while the fuel was melted. How could it melt? The best judgement on this side of the Pacific is, this spent fuel pool either splashed nearly dry during the Richter 9 earthquake, or more likely, it leaked due to the quake.
This hydrogen explosion drove fuel outside the nuclear plant, and may explain the hot spots of radiation scattered over two prefectures. If people stay away from these hot spots, they should be OK.
The rest of the reactors are reasonably safe.
Thanks to God and the loyalty of the Fukushima Fifty.
And, child doses, even to the thyroid, is minimal. 900 infants were tested and are OK. My apology for optimism below, may have been premature. http://www.jaif.or.jp/english/aij/member/2011/earthquakereport41.pdf
The United States Department of Energy has flown over the Fukushima area and recorded the radiation. http://blog.energy.gov/content/situation-japan
Maximum doses outside the plant are less than 0.03 Rem per hour. That means 100 hours would get people 3 Rem, or 1000 hours would give 30 Rem.
30 Rem is where doctor's can test the blood, and find minor changes. Below that level, there are no short-term effects.
The radiation has dropped by a factor of ten in two days. Unless something major happens, the people will not ... repeat, not, get more that 30 Rem. No short-term effects.
That leaves cancer and other major illnesses.
The total release cannot be accurately estimated - yet. Japan and the utility, TEPCO, have not released enough information.
Nuclear reactors have several layers of defense against a release. The innermost one is the fuel itself. It is hard to melt this ceramic fuel. Second is a primary cooling system, with steel walls. Third that is a containment building, with steel lining and reinforced concrete strength. Fourth is a reactor building, which protects the containment.
But, the fuel and primary coolant system of three plants (1,2,3) are severely damaged or melted (and re-frozen). The containments of all three are functional, although one is damaged. Radiation within the fuel has decayed so much that it is highly unlikely that any containment will be further damaged. This means that the reactor fuel will stay in the reactors - all but about 1 percent, which has already been released. Plants one and three had hydrogen explosions outside the containment, but inside the reactor building.
And, the fuel in one spent nuclear fuel pool - for unit 4 - has been damaged and probably melted. This is the unit which had a hydrogen explosion, and it apparently happened while the fuel was melted. How could it melt? The best judgement on this side of the Pacific is, this spent fuel pool either splashed nearly dry during the Richter 9 earthquake, or more likely, it leaked due to the quake.
This hydrogen explosion drove fuel outside the nuclear plant, and may explain the hot spots of radiation scattered over two prefectures. If people stay away from these hot spots, they should be OK.
The rest of the reactors are reasonably safe.
Thanks to God and the loyalty of the Fukushima Fifty.
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