Thai nuclear agency keeping close watch after stolen Caesium-137 melted in a Prachinburi plant

The office and the provincial administration, however, refused to name the factory where the melting of the dangerous radioactive canister had been conducted.

Officials told a press conference that experts from the OAP and the Disaster Prevention and Mitigation Department had checked five metal recycling factories in Prachinburi’s Si Mahapho and Kabin Buri districts on Friday and Sunday and one of them was found to have “melted" the canister.

Police will investigate how the cylinder ended up at the factory.

The officials told reporters that no radiation leak from the stolen canister had been detected in the factory, as it used a closed system to melt the used metal scraps and it had retained the metal dust from the process for safe disposal.

The press conference at 11am on Monday was chaired by Prachinburi Governor Narong Nakhonjinda, Prachinburi chief public health officer Dr Surin Suebsueng, Prachinburi police chief Pol Maj-General Winai Nutcha, and OAP secretary-general Permsuk Sajjapiwat.

The officials said that the red dust left over from the metal melting process had traces of Caesium-137. No details were given on the level of contamination.

The officials said specialists from the OAP have checked the metal pieces made from the melting and did not detect any radioactivity.

The OAP officials also checked the quality of air and water in the factory compound and around it and did not detect any radioactive contamination.

The press conference was told that the red dust from the melting process was contaminated because when the Caesium-137 canister was melted, the isotope vaporised but it was trapped inside the melting pot.

The officials said the melting pot has a filtering system to trap the waste from the process so the contaminated dust does not leak into the environment.

The officials said that the OAP was in control of the situation by prohibiting the transfer of the dust and has taken upon itself the task of disposing the dust of safely.

Permsuk said the red dust from the melting process was contained in 24 big bags. One of the bags was used to fill a land behind the factory but officials had retrieved the dust and also excavated contaminated soil for disposal.

“Please understand that the melting dust had limited contamination, which has been restricted and controlled by OAP specialists,” said Kitkavin Aram-aroon, chief of the emergency radioactive operation at the OAP.

“The Caesium-137 isotope has not leaked into the environment and will not affect the people in Si Mahapho, Kabin Buri and Prachin Buri. Please don’t panic. The situation is under control.”

OAP officials also checked all the workers who had taken part in the melting process, and did not find any radioactive contamination on them, the press conference was told.

The OAP on March 10 alerted the Civil Disaster Prevention and Mitigation about the stolen radioactive canister from the National Power Plant 5 A.

Initially, officials launched massive searches for the canister, which was five inches wide and eight inches long and weighed about 25 kilograms in the power plant and around the area. They also searched shops in the area that buy metal scraps.

The radioactive canister had been in use for 28 years. The Prachinburi police chief said it was definitely stolen from its container and did not fall off by accident.

Officials have been checking steel factories in the province, 150 kilometres east of Bangkok, since a cylinder of caesium-137 was discovered missing from a coal-fired power plant in Sri Maha Pho district on March 10.

On March 17, officials checked the Yong Shing Steel (Thailand) metal recycling plant in Tambon Hua Wa in Si Maha Pho.

Then on Sunday, officials checked four other recycling plants, Chao Steel Industry, KPP Steel, TSB Steel and Sing Thai Steel.

Jessada Denduangboripant, a lecturer at Kasetsart University’s Faculty of Chemistry, on Monday called on the authorities to reveal the full truth on the level of contamination in the red dust.

He said the red dust was caused by the normal process of melting of metal scraps but it would be very dangerous to humans if the dust was contaminated with a high level of radioactivity.

Jessada said it would be dangerous if the dust leaked during the melting process and the radioactive chemicals might also be melted into the process piece of metal.