Radioactive release from Norwegian research reactor

Tuesday, 25 October 2016

UPDATED - The NRPA has found no unusual radiation levels either on or off site, and IFE has said the emissions have stopped.

A small amount of radioactive iodine was released into the environment yesterday during an incident involving the handling of test fuel in the reactor hall of the Halden research reactor in Norway.

The Institute for Energy Technology (IFE), which operates the reactor, said a "technical fault" occurred at 1.45pm yesterday whilst fuel was being handled in the reactor hall. At that time, the reactor itself was offline for maintenence. The incident resulted in the release of radioactive Iodine-131 and Iodine-132 to the reactor hall and led to an emission into the environment.

Workers immediately left the reactor hall when an alarm sounded, IFE said. None of them, it noted, was found to have received any significant dose of radiation.

The Halden reactor hall (Image: IFE)

The Halden reactor hall is covered by 50 meters of rock. Access to the hall is through a 50 meter-long tunnel, which is supplied with an air lock of concrete walls and steel doors.

In a statement today IFE said, "The reactor's protection systems functioned as designed, which reduced the emissions considerably." Personnel have since re-entered the reactor hall to identify the cause and extent of the leak.

IFE said it has notified the Norwegian Radiation Protection Authority (NRPA) of the incident and that the local municipality of Halden and the local police have been informed.

According to the NRPA, the release is estimated to have been 150 megabecquerel of I-131 and 24 MBq of I-132. This, it notes, is "small and constitutes 5% of the amount of radioactive iodine IFE is permitted to discharge yearly". It added, "According to the information received so far, this discharge will not have any consequences for health or the environment outside the plant."

NRPA director Per Strand said, "Our focus now is that IFE manage to stop the leak. We are in continuous contact with IFE. We will start a new inspection round relating to this incident to uncover how this could happen and why we were not notified until the day after."

In a subsequent 25 October statement, the NRPA said it had conducted independent measurements at Halden and "could not detect unusual levels of radioactivity on or off site". It added that IFE had said "the situation is under control and the emissions have stopped".

The Halden nuclear fuel and reactor material testing reactor - which started up in 1959 - runs at a maximum power of 20 MWt and contains numerous test positions thus providing flexible test conditions. About 30 test rigs are currently installed in the reactor core. A number of in-reactor loops are installed for performing experiments under prototypical coolant conditions. These loops are in particular utilized for corrosion and stress corrosion studies and for water chemistry investigations.

The Halden project is a joint undertaking of national organisations in 19 countries sponsoring a jointly financed programme under the auspices of the OECD Nuclear Energy Agency. The program is financed by the participating countries and is renewed every three years. As a host country, Norway covers about 30% of the program cost.

Researched and written
by World Nuclear News