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 Sunday, they detected readings of radioactivity at the province’s largest steel foundry, in Kabin Buri district. The readings came from scrap metal that had been compressed into cubes ready to be smelted on Sunday evening.
Officials ordered the foundry halt operations to prevent the radioactive metal from being crushed and scattered into several cubes.
All employees were ordered to leave the foundry, where a perimeter has been set up to bar access to outsiders.
An initial investigation of smelted material at the foundry found traces of caesium-137, he said.
Ronnarong said earlier that the cylinder is suspected of having been stolen for sale to a junk shop.
Caesium-137 has a half-life of about 30 years and remains in the environment for 300 years, according to Ronnarong. He warned that touching the radioactive material can harm the skin, liver and bone marrow.
Provincial public health and labour welfare officials last week set up a command centre to search for the cylinder and handle any fallout from the incident.
The province also announced a 50,000-baht reward for those who provide information leading to its recovery.