Q: How much of that has been released, and what are the effects of that?
A: The uranium fuel rods inside each reactor are still expected to be largely intact. If the reactors are cooled down over time, the rods will be disposed off as radioactive waste. The spent rods, which were usually stored in a pool near reactor number, are radioactive -- or hot -- and will be leaking radiation until they are fully submerged with cool, distilled water and return to a normal temperature.
At least one of the pools of spent fuel rods is completely dry and out of control.
Trace amounts of Cesium-137 and Iodine-131 were found in the air around the plant starting March 12, around 1:30 p.m. local time. The two isotopes are produced when the fuel rods inside the reactors overheat and react with their casings. Both are radioactive and can cause health damage. Iodine has a half-life, or reduces in mass and thus radioactivity, every eight days -- within two months, it leaves no trace behind. It can be countered with doses of potassium iodide tablets, but only within 24 hours of exposure. It is known to cause thyroid cancer.
Cesium has a longer half-life of about 300 years. External exposure to large amounts of Cs-137 can cause burns, acute radiation sickness and even death. Exposure to Cs-137 can increase the risk for cancer because of exposure to high-energy gamma radiation. Internal exposure to Cs-137, through ingestion or inhalation, allows the radioactive material to be distributed in the soft tissues, especially muscle tissue, exposing these tissues to the beta particles and gamma radiation and increasing cancer risk.
Q: How much of this material is out there?
A: So far, very small amounts of cesium and iodine are reported to have been released, mostly in a process when engineers are venting pressurized gases out from near the reactors core, to chambers outside it, where leaks and explosions have spread it out.
How much Cesium or Iodine remains inside the nuclear reactors is the big unknown -- the fuel rods have been partially submerged several times, and the temperatures have risen each time. If engineers can get control of the reactors, and finish the cooling process, then this radioactive material should be entombed within the reactor itself.
If the cooling process fails for any reason, and the containment chambers are sufficiently damaged, this material could leak out. This is the worst case scenario.
Most of the dispersed radiation is from gases that have short half lives: once the leaks are contained it will dissipate quickly.
Naaah, I dont consider Cesium 137 as a "short lived nuclide". And its volatile besides. Ive seen reports of Cs in the atmosphere and that tells us that at least some of the Zr cladding has been compromised
George said unequivocally thatall the radionuclides that were emanating from the steam were "short lived"
re-posted on this page: "most" isn't "all".