a******e
发帖数: 17 | 1 以下是我一个哈佛物理博士朋友的回答。但愿能给你一点安慰。。。
Our family is planning a east coast vacation (for real) to outrun the
nuclear cloud drifting our way... I am kidding, but you may find the
following information entertaining, and potentially educational.
We need to put any risk in perspective. The main stream media is playing a
constructive roles here to report the risk as justified by the information
available and by the possible worst-case scenarios. Risk cannot be
discussed without quantification, otherwise it become fear-mongering. The
only reason residents in San Diego needs to buy iodine is if one expect San
Onofre nuclear reactor in Carlsbad somehow may explode. We should keep in
mind nuclear fuels, whether uranium or plutonium (as in MOX), are naturally
existing elements in the earth's crust at very low concentrations. If you
tour Utah when you visit some of the beautiful national parks there, you
have already gotten a much higher radioactive exposure than anything the
Japanese reactors can do to you in the US. If the nuclear fuel of the
Japanese reactors in question is to be evenly distributed across the state
of California, I don't think the radiation level is even measurable, unless
by some magic an orders of magnitude higher concentration lands near where
you live.
So let's worry about a few things around us first, before the Japanese
reactors do strange things to us half a world away:
1) You are being bombarded 24/7 by cosmic rays ever since you are born.
There is one high energy (MeV) particle per centimeter square per minute
going through your body, potentially causing a mutation in the gene.
2) Our environment is naturally radioactive. If you turn on a Geiger Muller
counter, you will get ~30-50 counts per minute no matter where you are.
3) If you have granite countertop at home, you might measure ~50-150
directly on the countertop. So if you sleep on your kitchen countertop for
8 hours a day, you will get 2x the dose an average person get in a day. A
layer of drywall will cut the exposure in half, so wall the distance.
4) If you eat banana, you are have already swallowed radioactive materials.
Do you know banana (the potassium-40 in it) is the leading cause of nuclear
false alarm at border crossings? A high percentage of container trucks
carrying banana trigger false alarms at the border crossings. If you eat
one banana a day for a year, it will increase your risk of getting cancer by
~0.5 part in a million. Whereas all the food you eat in a year, the total
radioactive dosage will increase your cancer risk by ~4 part in a million.
Of course if you don't eat, you will die in a week.
5) There is a hideous substance we are exposed to everyday, swallowing a
large amount is known to cause death. This chemical, di-hydrogen monoxide,
also know as DHMO, is considered so hazardous that our environmentally-
conscious city council in Alis Viejo, California drafted a law to ban its
use within the city, until they found out...
http://en.wikipedia.org/wiki/Dihydrogen_monoxide_hoax
PS: Some useful information: Cancer risk is associated with ionizing
radiations. Common types include alpha, beta, gamma, and neutron. Alpha (
the helium nucleus) and beta (electron) are charged particles. The stop
range is no more than a few dozen microns, more commonly a few microns, so
they normally do not penetrate the dead skins. Alpha and beta emitters are
not hazardous unless you swallow or inhale it. Gamma is a type of hard x-
ray, will penetrate many centimeters into human body. Neutron can penetrate
through meters of concrete. So both gamma and neutron are of concern if
the environment is contaminated even without inhalation/ingestion. Both
uranium and plutonium generates gamma and neutron radiation. Uranium
poisoning is usually curable as the biological half life is only ~ a day (
not to be confused with the decay half life which is on the order of a
billion year). This is because uranium get oxidized very easily and the
oxide is soluable in water. Drink a lot of water and the stuff will leave
your body in a day or so. Plutonium is said to be much nastier. Thorium,
which is a by-product of uranium/plutonium reactions, bonds to the bone, so
it will stay in the body for the rest of the persons life (biological half-
life=decay half life=75000 year). Someone (from Health Physics) told me
before that the iodine antidote can stop or slow the bonding process,
however, I haven't been able to find similar info on the web so don't know
whether this info is correct or not.
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