Posted on 11/27/2010 10:04:54 AM PST by MindBender26
Need some help from a Nuckie. Am former reporter who has been to Chernobyl twice (no radiation problems, but could read without a nightlight for a few weeks....)
Need someone who can shed light (sorry about pun) on the concept of Criticality Accidents, AKA Nuclear Excursions, such as killed Louis Slotin 65 years ago.
These accidents have happened a number of times. The fisionable materiel does not explode as a nuclear bomb does, but achieves criticality, so a huge amount of radiation is released.
Can anyone speak knowledgedly on this issue?
I did Yucca Mountain stuff and wrote a book on some of the issues. In general, Chernobyl was a freak accident in that the Russians had essentially no containment and were using graphite as the moderator - it’s like apples and oranges to our water reactors. Three Mile Island was essentially a non-event. That isn’t to say our designs don’t have problems, but we should have moved on to third and fourth generation designs. Three Mile was second generation, I think Chernobyl could be considered first generation.
Criticality accident number one: The demon core.
They were bringing the core halves together and seperating them with a screwdriver.
Well, the screwdriver slipped the core pieces came together, and the room was bathed in blue-ish light.
The guyy closest to the demon core ripped the pieces away from each other with his bare hands.
Yes, he died later.
The demon core became the reactive core to one of our first nukes.
Just Google “Hanford Downwinders”:
“The Green Run
Activities at Hanford resulted in the release of large amounts of radiation into the air, water and soil of the Northwest over several decades. Many of the radiation releases have exceeded permissible limits. Some of the radiation releases have admittedly been intentional, a way of conducting Cold War nuclear experiments on an unknowing and captive population. All of it was done in the name of the national security and the rush to produce more and more plutonium.
The largest intentional release of radiation at Hanford occurred in 1949, and is known as the “Green Run.” The public was unaware of this event until some 40 years later, in the late 1980’s, when the DOE first declassified release reports acknowledging that the Green Run had occurred and then only after a newspaper reporter sued the agency.
Documents showed that Hanford intentionally and secretly released about 8,000 curies of radioactive iodine on Dec. 2, 1949. Allegedly the radiation was released to monitor the radioactive plume stretching across Oregon and Washington in hopes of evaluating equipment used in determining the location of similar Soviet plutonium production plants.
The Green Run was a huge release by any standard. The 1979 Three Mile Island accident released between 15 and 24 curies of radioactive iodine, several hundred times less than the Green Run, and nearby residents were evacuated from the area.
No one living downwind from Hanford was ever evacuated or warned of the Green Run or any of the other radioactive release from Hanford. Spanning more than 40 years, a set of 400 environmental documents were made public in 1986. These documents revealed that Hanford regularly emitted radiation into the environment. Between 1944 and 1947 the total estimated radioactive iodine released from Hanford was at least 685,000 curies; a truly staggering amount.”
http://www.djc.com/special/enviro98/10043971.htm
My question is, in a situation such as you describe, if the spheres were left together, for how long would they emit that large level of radiation?
My question is, in a situation such as that, if the spheres were left together, for how long would they emit that large level of radiation?
Would they run out of fuel shortly?. Would they melt? Whould then then go into an extremely high temperatire meltdown?
Radiation?
The problem of criticality is with neutrons.
The result may be a dynamic instability.
Please see #3 and #7.
Thanx
Doctor remembers Hanford’s ‘Atomic Man’
This story was published Friday April 25th 2008
By Annette Cary, Herald staff writer
Dr. Bryce Breitenstein speaks with admiration for the patient at the center of his most famous case — the Prosser man who came to be called “Atomic Man” after surviving the nation’s worst radiological accident.
http://www.hanfordnews.com/2008/04/25/11403/doctor-remembers-hanfords-atomic.html
There are quite a few.
Here's a link to start you.
Until Geometry was lost, or the neutron life-cycle was broken
1950s technology... at best. For example, no paper recorders or telltales on meters. Constant nuisance alarms.
Time?
For as long as enough plutonium existed to release the neutrons.
Which could have been several days, or could have been less than a minute before a fizzle explosion occured, scattering radioactive debris over a large area.
The Demon Core did criticality accidents to two people
Harry K. Daghlian Jr and Louis Slotin, the core was later disposed of in the nuclear shot ABLE during Operation Crossroads.
Other criticality accidents have only lasted milleseconds, some for as long as twenty minutes.
It would get so freaking hot it would melt and then it would no longer have the density to remain critical.
Thats the line that was used to describe Chernobyl. Criticality was lost due to deterioration of Core Geometry.
(Ie it blew itself up)
At Chernobyl in 96, met firefighter who was at reactor. Received 380 rads in one night. Survived.
He was 34, looked 64.
I was a nany nuke, from what I know, all reactors go super critical when k effective is greater than 1. It means they’re producing lot’s of fast neutrons.
The Demon Core incident would have lasted a few minutes since it involved a subcritical mass of plutonium trapped in a neutron reflecting sphere of beryllium, which brought it to criticality. Once it had melted its way through the sphere and was no longer in a neutron reflector, the reaction would have stopped. It still would have been a very high energy incident with significant local contamination.
Slotkin received the lethal dose of radiation in under one second.
Fallout is the danger, not the uncontrolled reaction. The effects of the reaction would have been quite localized, but contaminated smoke from a fire could have spread significant fallout.
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