Whole body counting ( WBC ) is the most direct approach, but has some limitations : it cannot detect beta emitters such as tritium; it provides no chemical information about any compound that the radioisotope may be bound to; it may be inconclusive regarding the nature of the radioisotope detected; and it is a complex measurement subject to many sources of measurement and calibration error.
22.
Thyroid doses for adults around the Chernobyl area were estimated to be between 20 and 1000 mSv, while for one-year-old infants, these estimates were higher, at 20 to 6000 mSv . For those who left at an early stage after the accident, the internal dose due to inhalation was 8 to 13 times higher than the external dose due to gamma / beta emitters.
23.
Caesium-137 because it is a long-lived high-energy beta emitter with a half-life of 30.17 years is one of the two principal medium-lived fission products, along with strontium-90, which are responsible for most of the radioactivity of spent nuclear fuel Caesium-137 beta decays to barium-137m ( a short-lived nuclear isomer ) then to nonradioactive barium-137, and is also a strong emitter of gamma radiation.
24.
Tritium is a low-energy beta emitter commonly used as a radiotracer in research and in traser self-powered lightings and some " beta emission from tritium are so low in energy ( average decay energy 5.7 keV ) that a Geiger counter cannot be used to detect them . An advantage of the low energy of the decay is that it is easy to shield, since the low energy electrons penetrate only to shallow depths, reducing the safety issues in deal with the isotope.
