flowers said:
Jackson_Bill said:
jrista said:
Jackson_Bill said:
You all realize that bananas, potatoes, and even beer is radioactive due to the presence of the naturally occurring K-40 (potassium 40) isotope, right?
8) Yeah, but that's one of those semi-stable isotopes with exceptionally long half-lives. K-40 has a half life of 1.25 billion years! The dose in a banana is about 0.1µSv, or 0.0000001Sv. For the average human, radiation doses under 100mSv (0.1Sv) per year have no measurable health effects. You would need to eat one million and one bananas in a year to experience the most minimally measurable health effect due to potassium-40 radiation exposure. (I actually don't think that is humanly possible, to eat that many bananas.)
All true, Jon, although another way of putting it is that the Nuclear Regulatory Commission limit on dose to the public (above background) is 1 mSV, which, I agree, is still a lot of bananas
.
My point was that we are exposed to many sources of radiation, natural and man-made, every day. The implication (in some posts) that Fukushima caused some measurable increase in the dose from lenses manufactured in Japan is bogus. Discussion of radioactive lenses isn't really meaningful unless you consider the associated dose, which is likely to be very small, if measurable at all.
The amount of radiation in some areas in Fukushima at this very moment is 25 Sieverts/hour. Not millisieverts, sieverts. Every hour. Of course those areas are very close to the reactor, but with all the contaminated water and the workers running out of places to put it and more and more of it spreading to the ground water plus all the other radioactive waste and gases spreading it's a little naive to say that it's impossible that the radiation levels of lenses manufactured so close to the plant haven't increased at all.
https://www.youtube.com/watch?v=3LyqsN38BSc
Takumar 50/1.7, radiation: 0.08 mSv/hour (back of the lens), 0.007 mSv/hour other parts, average. That's 61 mSv/year from most parts of the lens, 700 mSv/year from the back of the lens. That's sixty-one and seven hundred, the latter number is more than 100.
Please at least find out the numbers before you speak up.
Of course if the radiation levels were really so users of those lenses were in significant increased danger of getting cancer (which starts from a
single mutated cell by the way) I guess we wouldn't be joking about it with such levity. Or would we? Who knows. Like all artists, photographers are crazy
Crazy!
edit: oops, I got the numbers crazy wrong! I blame the meter... I watched the whole video again after I realized the numbers didn't make any sense. Ha ha! Numbers corrected.
@Jackson_Bill: Oh, I totally agree with you about Fukushima! Totally overblown by media hypersensationalistic fools who wouldn't know their asshole from a rathole.
The problem is people don't understand that there are different kinds of radiation, from EM to beta particle decay to hard alpha decay. They also don't understand that not all radioactive sources are the same. Release of plutonium would be a serious problem, especially at 25 Sv/hr, but that isn't what's happening.
There are heavier unstable isotopes like plutonium and uranium that, as they decay, produce both hard radiation (
alpha and beta particles as well as ultra high energy gamma ray) and further radioactive materials that will continue to decay, sometimes via the same hard alpha-particle process. There are also lighter unstable isotopes, like the stuff at Fukushima, that decay quickly into smaller STABLE isotopes. The energy levels of lighter weight isotopic decay are much lower than with heavier isotopes as well, and it is usually not the same kind of highly reactive and dangerous alpha particles or ultra high energy gamma ray radiation...instead you get beta decay (release of a free neutron, which further decays into an proton, electron and a neutrino within seconds) and low energy gamma ray radiation.
So the "reach" of the radiation being released at Fukushima is also not as high as it was in the case of Chernobil. (Chernobil was an unmitigated disaster propagated by the utter foolishness of the Russians (the Russians just work differently...have you ever watched those videos on YouTube about how the Russians drive and have car accidents all the time...it's rather insightful!! Them pplz is CRA-ZY!
:
) The Russians built the least safe and least contained reactors I think the earth will ever see, so when their reactor melted down, it literally melted down and released a highly radioactive radiation cloud that rained down dangerous particles like plutonium, uranium, and closely related derivatives as well as a whole host of lighter radioactive isotopes into the surrounding environment. Un-miti-gated disaster. Will never happen again. Because of Chernobil, the countries that use nuclear energy do so with ultra hardened reactors with multiple levels of containment. The general design is a central containment vessel for the actual nuclear reaction, where the fuel and control rods are, a surrounded by a containment vessel for coolant, further surrounded by a concrete core containment vessel designed to contain a complete meltdown of all nuclear fuels, and a final outer containment vessel surrounding the concrete core and the inner containment vessels. A disaster like Chernobil is practically impossible, even if an earthquake causes damage, you would effectively need the earthquake to be right on top of the plant and crack all the containment vessels right through to the core in order for plutonium and uranium to be released.)
The kind of radiation that is occurring at Fukushima is due to the pumping of water through the reactors to cool them down. The reactions within the reactor cores are uncontrolled or nearly uncontrolled. I do not know for sure if there were full meltdowns or only runaway reactions that are barely controlled, but it still produces a tremendous amount of heat and EM radiation. That radiation has the tendency to produce lighter radioactive isotopes as it reacts with particles in the coolant water (which is seawater, which contains a number of stable elements that can be temporarily converted into radioactive isotopes under the right conditions.)
Fact is, those are really short lived isotopes, with half lives on the order of minutes, hours, or days. The radiation that makes it into the oceans is going to be absorbed pretty thoroughly. Within a month of any contaminated water leakage being finally stopped, it would probably be pretty tough to detect any radiation in the nearby ocean water. Another thing most people don't understand is that the ocean is a heavily buffered solution, and it'll absorb pretty much anything and everything without there being terribly adverse reactions to the ecosystem. (There may be some very long term benign affects over the coming decades and centuries, and for marine life right off shore, there may be some more immediate affects under prolonged exposure.)
So, it may be 25 Sv/hr, but it isn't 25 Sv/hr of super deadly radiation from plutonium or uranium particles or anything like that which decay via alpha particles and high energy gamma rays (hard radiation) to further radioactive materials and so on (that's why plutonium is so dangerous, the radioactive decay continues on and on once it's in your system, continuously wreaking havoc). It isn't a cataclysmic issue like many would have you believe. It's short-lived light isotopes that decay quickly into stable isotopes that can't decay further.
The radiation is largely contained to Fukushima and the surrounding ocean, and is relatively short lived. So I wouldn't expect any lens manufacture nearby to result in a whole bunch of radioactive lenses.
I'm pretty sure my grandmother's dishware had a high uranium content in it though because it glowed bright green even in sunlight 
