To examine inshore radioactive contamination caused by nuclear power plants, nuclear testing, hospital and laboratory, both gross β-radioactivity and γ-spectrometry were measured. The measurements were taken with the Abalone and Top shell, which had been collected from the four different sites at the coast in Jeju-do (Seongsan, Deajeong, Wimi, Dodu). The activity ranges of concentration were respectively 0.11~0.29 Bq/kg-wet for 90Sr, 0.01~0.04 Bq/kg-wet for 137Cs, 36~53 Bq/kg-wet for 40K in shellfish on the Jeju island.
The radioactivities of 90Sr, 137Cs and 40K were similar to those in sampling location of shellfish in the coastal on the Jeju island. The radioactivity of 90Sr for the Abalone was lower level than that for Top shell. The radioactivity of 137Cs for the Abalone was similar to that for the Top shell. But the radioactivity of 40K for the Abalone was higher level than that for the Top shell.
As a result, the gross β-radioactivity observed was similar to that in nature. Among radionuclides, only 90Sr, 137Cs and 40K were detected in a very small amount, and each was also close to the natural levels.