An orientation survey of radon in soil gas
- At Mora 6,
in the Karoo Formation, Folakara, Madagascar, by IAEA and OMNIS, 1984.
- Uranium mineralization buried under up to 18 meters of sandstone.
- Previously drilled by the French Atomic Energy Authority.
139 soil-gas samples taken from 30-cm deep holes at 10-meter spacing.
- Anomalies confirmed on different days.
Higher radon values, and higher ratios of radon to thoron
over mineralization as deep as 18 meters. Gamma survey does not respond
to this depth, nor does radium and uranium geochemistry of termite hills.
False radon highs have high thoron (low Rn/Tn ratios).
Similar high values of both isotopes occur on a small sand ridge south of Midwest
Lake, removed from the mineralization.
Higher levels of both radon isotopes in the absence of uranium mineralization is
because greater soil permeability releases larger amounts of both gases
into the sample hole.
- Measuring radon is not enough:
we also have to measure thoron to check for these false "permeability" anomalies.
- A similar survey at Mora 13, where the section overlying the mineralization includes shale
layers, gave negative results. Shale is impermeable and blocks upward migration of radon.
We measure: radon - radium - thoron - radon daughters - alpha radiation.
is recognized as the most sensitive and reliable method for these elements.
Our instruments are used around the world in exploration for uranium, oil & gas, groundwater and hydrothermal,
and in environmental protection, health physics, earthquake prediction, and evaluation of hydrocarbon and NAPL contamination.
In the radon business since 1968, our latest major instrument update was 2015.
Modern, low-power, field-rugged electronics. Some earlier versions still working after 35 years.
Continuous real-time monitoring and data recording.
Winter and summer, from the Sahara Desert to the Canadian Shield, our instruments have faced up to severe field conditions.
- Intrinsically safe functions.
Sensitive to geochemical trace levels necessary for radon in lake water and for radon-thoron isotope ratios.
Can work in a tent without electricity or be carried from point to point in the field.
50 readings per day. Results available immediately.
Rechargeable battery pack good for a long day in the field and recharges in a few hours.
Can be operated by junior personnel if carefully supervised.
Same instruments used for radon and radium in soil, sediment,
plant parts, rocks, water, soil gas, air, and snow, and for radon daughters in air.
- EPA compliant.
Click here for more details of instruments.
Click here for or other instruments, components and
accessories we provide
Technical specification sheets and pictures of our instruments provided on request.
Multilingual consulting and training (if required).
For instruments contact|
R.H. Morse & Associates Ltd.
Robert H. Morse, Ph.D., P.Eng.
January 25, 2010
radon counts per minute / ratio of radon to thoron
Based on radon counts per minute and ratio of radon to thoron
Strong: Rn>75 and ratio>0.9 or Rn>50 and ratio>3
Marginal: Rn>37 and ratio>0.6
Background:Rn<38 or ratio<0.7
False:Rn>100 and ratio<0.7