The incident was qualified as “serious” and installation preparation protocols were initiated.
A nuclear reactor in Finland went into automatic shutdown after a peak in radiation was detected in the plant’s systems on Thursday, but no radiation escaped from the facility.
“This is a significant and exceptional incident and we consider it important to disseminate correct information about it,” Finnish Minister of Social Affairs and Health Aino-Kaisa Pekonen told reporters. .
The high readings came from a room that regularly showed higher readings during normal operations, and no employee of the utility company had been exposed to the radiation or been injured.
Jarmo Tanhua, CEO of nuclear power plant operator TVO, said the incident was an unprecedented event in the facility’s history. TVO is a consortium of energy and industrial companies.
“There is no danger to people or the environment” following the incident at the Olkiluoto 2 power station in western Finland, said Tomi Routamo, deputy director of the safety authority nuclear STUK.
Although radiation levels around the plant are normal and there has been no external leak, STUK described the incident in a tweet as “serious” and said preparedness protocols had been launched in collaboration with the plant operator, TVO.
STUK later announced, “The situation is stable and the plant is safe,” and radiation levels have returned to normal.
“No such event has happened in Finland before,” Routamo added.
The automatic systems have detected high levels of radioactivity in the steam lines of the reactor cooling system, although the cause of the spike is not yet known and investigations are underway, according to Routamo.
A previous water pipe fault occurred at another Finnish nuclear power plant around 30 years ago, but the Olkiluoto incident concerns the so-called primary circuit pipes which are closer to the reactor and therefore face higher radiation concentrations.
The International Atomic Energy Agency (IAEA) said in a statement it had been made aware of the incident and was in contact with Finnish authorities.
The operator of the TVO plant said an automatic reactor shutdown, or “scram”, was triggered at 12:22 local time (10:22 GMT).
“It was closed automatically for some reason we don’t know, and nothing really happened,” said TVO spokesman Pasi Tuohimaa. “There is no harm anywhere.”
The Olkiluoto 2 reactor, which began operations in 1980, will be “driven to a safer condition” so that investigations can be carried out, Routamo said.
“They have to check that everything is fine, then they have to have our authorization from STUK to restart the reactor,” Routamo added.
Finland receives about a third of its energy from nuclear sources and two new nuclear reactor construction projects are currently underway in the Nordic country.
The most advanced of them, a third reactor at the Olkiluoto site, is more than 10 years behind schedule due to delays with the plant’s supplier, the French consortium Areva-Siemens.