Determination of activity concentration of Radon-222 by using its daughter progeny Pb-214 and bi-214 in water by using Gamma spectrometry / Elly Munirah Marzuki

In this thesis, low background gamma ray spectrometer has been applied to
determine the activity concentration of radon-222 in water collected from
ex-mining’s lake at Universiti Teknologi MARA Training Centre,
Kampung Gajah, Perak. This is simple method, where we just only
measure the sample waters with a germanium (Ge) detector using the
gamma rays spectrometer from the radon-222 daughter nuclides Pb-214
and Bi-214. Sample water collected are directly pour into Marinelli beaker
and sealed and stored for 3 weeks to allow radon-222 and daughter
nuclides were in radioactive equilibrium before counting. The radon
activity concentration is determined by taking the average weighed of the
concentrations derived from γ-ray lines associated with Pb-214 and Bi-214
decay. We cannot direct counting radon-222 by using gamma spectrometry
because it’s not emitted gamma radiation, but it’s is alpha emitted
radionuclides. In this study, the activity concentration of radon-222 is
higher at location 11 either for unfiltered and filtered water samples, which
is 4429 Bq/L for unfiltered and 10015 Bq/L for filtered water samples.
While, the lowest activity concentration of radon-222 for unfiltered and
filtered water samples was investigated at location 1 and location 2 with
the values 1328 Bq/L and 3308 Bq/L respectively. The activity
concentration of radon-22 in this study area is higher and need more
attention from related authorities because it can give higher percentage of
risk of radiation at that area.