This was the assumption of Vuong Huu Tan, head of the Viet Nam Agency for Radiation and Nuclear Safety (VARANS).
"The value of the radioactive materials is only a few million dong, so I do not think the thief stole it for use," Tan told the press conference on Thursday.
"It is because the use of radioactive material requires a licence."
"The radioactive material, Cs-137, is small and kept in a lead container. So the thief might have wanted to sell the lead container," he said.
At present, the authorities were searching for the missing materials at the workshops which collect and recycle scrap in the province, he said.
The search will last a month, Tan told the conference.
At the meeting, Deputy Minister of Science and Technology Pham Cong Tac also raised concerns about storing sand managing of radioactive material.
There have been six cases of radioactive material going missing nationwide since 2003.
"Fortunately, most of the missing radioactive material was stolen and sold as scrap. If the material came into the hands of the bad guys, that would cause a huge risk to national security," Tac said.
At present, the management of the radioactive materials has become more complicated because the source has been widely used in several sectors such as agriculture, industry and healthcare.
To further effectively manage radioactive sources, especially human-endangered radioactive material, since April this year, all such material will be attached with monitor devices, Tan said.
However, only 600 high-level radioactive materials will be attached to the devices, while more than 3,000 low-level materials such as the one at Bac Kan, will not be.
At present, the country has several used radioactive materials but they have not been stored in standard conditions, Tan said.
According to figures by the Ministry of Science and Technology, in Ha Noi alone, there are 35 used radioactive materials that needed storing.
Under the regulation of radioactive storage, the used radioactive sources must be stored in the national standard warehouse, but so far, Viet Nam has not constructed such a warehouse.
Recently, the government has agreed with the ministry's proposal to build the warehouse.
This year, the VARANS plans to collect all the used radioactive materials to ensure that none go missing, Tan said.
