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RE: Trivial-Adam-Mohan Radiological Units (TAMRU)
Finally, something we can use!
-----Original Message-----
From: Paul_Prichard@DOM.COM [SMTP:Paul_Prichard@DOM.COM]
Sent: Thursday, June 06, 2002 2:44 PM
To: radsafe@list.vanderbilt.edu
Subject: Trivial-Adam-Mohan Radiological Units (TAMRU)
The following is excerpted from an article of the same name written by a
John A. Adam in the March 1982 issue of Nuclear News.
Trivial-Adam-Mohan Radiological Units (TAMRU)
The assault on the environment by man-made radioactivity is of great
concern to the ordinary citizen, politician, and government official -
moralist and technician alike. I believe that the technician has failed to
fulfill his responsibility to accurately communicate the impact of man-made
activity in the environment.
Because of the large negative exponents that often occur in calculating
radiological impacts, a new system of radiological units that more readily
convey the significance of these calculations is needed.
Trivial-Adam-Mohan Radiological Units (TAMRU) is a proposed system of
measurement for use in state-of-the-art environmental assessments. The
fundamental units of TAMRU are:
Trivial (dose equivalent rate) is equal to the increase in exposure rate
due to an increase in cosmic radiation (measured at 0o latitude) that
results from an increase in altitude by one angstrom (10E-8 cm), = 10E-15
rem/yr. ("Trivial" is considered the most descriptive name for this unit.)
Adam (dose equivalent) is the exposure of one Trivial for one century, =
10E-13 man-rem. (A century was chosen as the duration of exposure since it
approximates the life span of man. The unit is named after the first man
in the account of Genesis.
Mohan (activity) is one disintegration per century, = 10E-20 Ci. This unit
is based on one curie of activity being mixed in the epilimnion (measured
in liters) of the Earth's waters. For oceans, the epilimnion is taken to
be 100 meters deep. (For most isotopes, this unit is a measure of the
probability that an atom of the isotope is present in the sample rather
than the activity of the isotope in the sample.) (This unit is named after
Mohan Thadani, who suggested the basis of the Unit.)
Derived Units
Parts-Beyond-Measurement (PBM) is one Mohan per kilogram, = 10E-20 Ci/kg.
(For the environmentally significant isotope radium 226, 1 PBM = 10E-17
ppm.) (The choice of the name for this unit is obvious.)
Mega-Trivial is the increase in exposure rate from cosmic radiation as the
result of standing on a thin sheet of paper at sea level, = 10E-09 rem/yr.
Radiological Undetectable Biological Effects (RUBE) is the loss of one
man-second of life (the consequence in the order of one giga-Adam
exposure.)
The conversion of TAMRU to other units of measurements should only be in
orders of magnitude, since one significant digit exceeds the limits of
accuracy for measurements performed in the ranges for which the TAMRU is
useful. Further, because of the uncertainties in the models and parameters
used in most environmental assessments, the error bands for the
calculations will exceed the magnitude of TAMRU units by many orders of
magnitude. This would suggest that the results of Trivial calculations
should be presented qualitatively as trivial and may not need to be
considered further.
Can TAMRU, which is based on quantities that are trivial and beyond
possible measurement, have any utility? Recent literature shows that the
mathematics for performing the calculations are available and are being
used. Hence, TAMRU would be a useful contribution to state-of-the-art
environmental assessments.
~~~~~~~~~~~~~~~~~~~~~~~~
Just an analog guy in a digital world.
Paul Prichard
Millstone Station
Paul_Prichard@dom.com
(860) 437-2806
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