Put this on your radar screens, at least for now:
Will Davis / from my iPhone 4S
NS Savannah Association
American Nuclear Society
Fuel Cycle Week
Atomic Power Review
As
readers of this list know, if the apartment dweller was breaking apart
smoke detectors, the most likely substance is a small amount of
americium-241. See below US EPA web page on smoke detectors and
radiation safety. If the user had uranium ore, the fissile component
would be the usual proportion of U235 more or less, but hardly a
dangerous source of radiation. The dangers come from inhalation and/or
ingestion of any heavy metal which confound the body's ability to
excrete it.
Dan Yurman
dan.yurman@outlook.com
Twitter: @djysrv Blog: NeutronBytes
Mobile: 216-369-7194
The news report does not identify the chemicals, but a guess would be, among others, hydrofluoric acid which can produce nasty skin burns on contact. http://emedicine.
Note
that the ANS Idaho section has for years worked with Idaho fire
departments to distribute smoke detectors for free to homes that need
them as a fire prevention measure.
Since
the news report mentions the NRC's comment about licensed
radioisotopes, it may be that the user also had a cesium-137 source
which is used in nondestructive testing of materials including concrete
on construction job sites. http://en.wikipedia.
How much radiation is in smoke detectors?
The
radiation source in an ionization chamber detector is a very small
disc, about 3 to 5 millimeters in diameter, weighing about 0.5 gram. It
is a composite of americium-241 in a gold matrix. The average activity
in a smoke detector source is about one microcurie, 1 millionth of a
curie.
Americium emits alpha particles and low
energy gamma rays. It has a half-life of about 432 years. The long
half-life means that americium decays very slowly, emitting very little
radiation. At the end of the 10 year useful life of the smoke detector,
it retains essentially all its original activity.
How much radiation exposure will I get from a smoke detector?
As
long as the radiation source stays in the detector, exposures would be
negligible (less than about 1/100 of a millirem per year), since alpha
particles cannot travel very far or penetrate even a single sheet of
paper, and the gamma rays emitted by americium are relatively weak. If
the source were removed, it would be very easy for a small child to
swallow, but even then exposures would be very low because the source
would pass through the body fairly rapidly (by contrast, the same amount
of americium in a loose powdered form would give a significant dose if
swallowed or inhaled). Still, its not a good idea to separate the source
from the detector apparatus.
Dan Yurman
dan.yurman@outlook.com
Twitter: @djysrv Blog: NeutronBytes
Mobile: 216-369-7194
No comments:
Post a Comment