Detection of Excessive Radioactive Materials in Underground Water

In more than one out of ten nationwide underground water places, radioactive materials exceeding the US standard were detected.

The National Institute of Environmental Research (NIER) investigated the contained four radioactive materials of Ladon, Uranium, gross-α and Radium for the nationwide underground water places last year. On January 27, the NIER announced that Uranium of 322ppb was detected in Saeum-dong Ichon-si Gyeonggi and the radioactive materials excluding Radium were detected in 20 places (dual detection in 3 places).

Among them, Uranium exceeding the US standard was detected in four places and Ladon (US standard of 4000pCi/L·pCi) was detected in 18 places. The gross-α was detected in one place.

The ministry of Environment announced that it took measures to prohibit the drinking or to conduct the proper treatment for the currently-used underground water among them.

However, as the result of a risk assessment with an average detection density of radioactive materials, a chemical risk of Uranium was 1/800 of the risk accepted by EPA of US. The cancerogenic risk of Uranium, Ladon and gross- α was 1/2~1/10000 of allowable value of the international radioactive material protection committee. So, the environment researchers said that the underground water is safe.

The risk is to calculate a degree of damages when a man is exposed to the radioactive material for 30 years on condition of 70 years of life and weight of 61㎏.

This investigation was conducted as one of the 4 years rock layers investigation project from 1999 for an actual inspection in a national aspect after the Institute of Basic Sciences of Daejeon announced that the Uranium was detected in the underground water of Daejeon area in 1998. As all investigations are completed last year, the distribution of radioactive materials was completed.

The ministry of environment decided to establish the domestic Uranium water quality standard based on the results of the investigation, and determined to specify the domestic standard referring to a case of advanced countries for Ladon applying a potential standard in US.

▽ Uranium = Uranium is contained in the underground water more than a surface water as an element producing α- ray and gamma ray when an atomic nucleus decays. It is accumulated in the human body and it destructs a renal function.

▽ Ladon = It comes out from a decay scheme of Uranium as the radioactive material in the national world. Ladon of the water is radiated in an air and absorbed through respiratory organ or digestive organ. Ladon is a main carcinogen causing a lung cancer and gastric cancer.

▽ gross-α = The gross-α is radiated from all radioactive nuclides such as the Uranium, Radium, Ladon and Plutonium. The gross-α is an indicator showing how many radioactive materials exist. It is, in itself, not harmful to a human body.

Sung-Hee Jung shchung@donga.com