Now,
back to "classifications".
Although we have
drifted from our goal from time to time, we have been attempting to
help non-technical visitors to understand the classification system
and the particular hazards associated with each classification. We have
tried to give examples of each of the hazard classes/dangerous goods
to help our visitors to grasp the real dangers in a non-technical atmosphere.
In our training classes we receive many comments about how we can provide
an example of almost anything that can go wrong with transporting dangerous
goods. Its not that we are so smart - no - more likely we have witnessed
so much we just can't resist climbing up onto our soapbox and start
preaching about safety. Learn from others' mistakes! Don't copy them!
Too often we witness
ostrich-like reactions to dangerous goods. To us, it seems that when
transportation and distribution people don't have an idea about what
they are handling, they tend to bury their heads in the sand. "Ignore
the problem." "Maybe it will go away." "If I don't
think about it maybe nothing will go wrong."
Of course this
is always a dangerous reaction that can cause property damage or injury
or death further along the transportation chain. Our topic this month
is radioactive material.
"RADIOACTIVE
MATERIAL - defined as any material that spontaneously emits ionizing
radiation and has a specific activity greater than 74 Bq. per gram (0.002
microcuries per gram). Note curies are no longer used to measure activity.
The not-so-new International Standard is "BECQUERELS (Bq)".
"Spontaneously
emits ionizing radiation" sounds like something out of a science-fiction
movie. Zap!
We come across
many forms of "radiation" every day. X-rays by the dentist
would be one form of that ionizing radiation. Other forms of radiation
are microwave, radio and TV, electro-magnetic (ultra-violet, infrared,
electricity, and ordinary light). They all share one common bond - wavelength.
The narrower wavelengths result in a more penetrating form of radiation
creating a more dangerous form of energy.
Radio, TV, infrared,
and ordinary light from a light bulb have very long wavelengths and
therefore present almost no danger.
Microwave has a
much narrower wavelength so that form of energy can produce heat and
may cause damage to cell structures. Cell phones use microwave energy
and we are sure you have all heard theories about potential changes
in brain cells (cancer) due to long-term and constant use of those phones.
However, there is no conclusive evidence at this time that cell phones
are potential health risk. On the other hand, cook a food item in a
microwave oven for too long a period of time and you have an example
of cell-structure-change. Bite into the food and its like biting a rock.
That's bad for the teeth and worse on the digestive system!
Ultra-violet radiation
from the sun has a fairly narrow wavelength and travels over millions
of miles through space and if you absorb large amounts of it due to
work or play in the sunlight, or in a tanning salon, you can increase
your risk of skin cancer. The ozone layer in the earth's upper atmosphere
provides us earthlings with some protection from ultra-violet radiation.
Fissile radioactive
materials, such as uranium, are used in nuclear power plants and, unfortunately,
in nuclear weapons. These products are indeed the most dangerous forms
of radioactive material but they also require extraordinary surveillance
by government agencies and security personnel, thus ensuring safety.
X rays, gamma rays,
radioactive isotopes are used in medicine and industry and usually have
very narrow wavelengths and thus present the greater risk to health.
These are the radioactive materials we generally see in transportation
and are the radioactive materials that we wish to address in this newsletter.
To protect the
public and the transportation personnel from radiation risks there are
at least four steps that must be used at all times.
Obviously, proper
identification of the radioactive source (radionuclides/radioactive
isotopes) is the first order of business. Iodine-131 (I-131) and Iridium-190
(Ir-190) would be two examples. Both are used in medical applications.
The source is noted in the contents section of the radioactive
label and also must be noted on the documentation.
Activity,
which really is the quantity of the radioactive material being shipped
in a package. Unlike other dangerous goods that are measured in kilos
or litres we are concerned with the amount of energy coming from the
source. This is measured in becquerels - the older method of measuring
quantity was curies. The "activity" portion of the radioactive
label must indicate this quantity and it is appropriate to use the international
standards such as giga becquerels (GBq) or tera becquerels (TBq) on
both the label and the documentation. If this boggles the mind, think
of an ordinary light bulb. We measure the amount (quantity or brilliance)
of light in "watts", not in kilograms or litres.
The quantity (activity)
of radioactive material being shipped will determine the packaging,
which is our primary method of providing safety. Knowing the quantity
for each radionuclide that we are shipping we can determine if the product
is within limits for a Type A package, the normal method of packaging
that provides a reasonable amount of protection from radiation and contamination
during transport. If we exceed the limits for a Type A package we must
use a Type B package which is designed and tested for containing large
amounts of radioactive material. Sometimes the amount of energy is so
small that no special packaging is required and no radiation protection
is needed.
The fourth method
of providing safety is to measure the amount of exposure from
the radioactive material. When we see Yellow II or Yellow III labels
on radioactive packages the labels advise us that radiation is being
emitted from the package. We measure that radiation on the surface of
the package and at one metre from the package with a Geiger Counter
of other electronic measuring device and the reading gives us a Transport
Index (T/I). That reading is placed on the Yellow II and Yellow
III labels in a box marked Transport Index. From that reading we can
determine two very important factors for providing safety to the public
and to transportation personnel - distance (from the source)
and time (of exposure). The T/I is the actual measurement of the radiation
level at one metre from the package. It is measured in "millerems"
per hour. The mrem lowers as you increase that distance beyond the one
metre. Therefore the amount of exposure per hour decreases as the distance
away from the radioactive package increases.
Recap:
