There was an incident at the research reactor in Garching FRM II in Bavaria. Although the reactor is at a standstill in the corona crisis, radioactive C-14 has leaked. A limit has been exceeded - but there is no danger to people.
Garching (dpa) - Radioactivity has leaked out at the FRM II research reactor in Garching near Munich. The annual limit value of the radioactive nuclide C-14 has been exceeded, said the Technical University of Munich as operator on its website.
A "slight overshoot" of the value specified in the operating license for the C-14 discharge through the chimney into the atmosphere was found. The operators and the Bavarian Ministry of the Environment, as the nuclear regulatory authority, emphasized that there was never any danger to people or the environment.
The annual limit for FRM II was exceeded by around 15 percent, FRM II spokeswoman Anke Görg said on request on Saturday. An evaluation on Thursday showed the value. According to the information, an assembly error in a drying facility was responsible.
When the limit value is exhausted, the theoretical burden on the population is a maximum of 3 microsieverts, says Görg. This is less than the value that a patient is exposed to when they have an x-ray at the dentist. According to the Technical University, it also corresponds to one percent of the annual radiation dose of 300 microsieverts permitted by the Radiation Protection Ordinance, which the population can be expected to derive from the discharge of radioactive substances in the air. The limit value for the C-14, individually set for the FRM II, is in turn far below the legally prescribed value.
The reactor has been operating indefinitely since March 17, due to corona restrictions, as visiting scientists are unable to work on site. The effects of the incident on further operations are open. The Environment Ministry in Bavaria had to decide on this. The latter announced that it had requested a report on the event, its causes and how to rectify it. The reactor would only restart with the approval of the ministry. "Protecting the population and the environment is a top priority when operating the Garching research reactor," emphasized the Ministry in Munich.
According to the Nuclear Notification Ordinance, the notification was classified as "urgent" in the "Category E", but according to the international rating scale (INES) it was level 0, which means no or very little safety-related significance.
The emissions took place from March 20 to 26 and April 2 to 7. In April, the increased value from the first quarter was noticed during the routine inspection by the Federal Office for Radiation Protection and the FRM II's own laboratory. The value was still below the limit specified in the operating license, but a monthly evaluation had been made. On Thursday, the overall evaluation showed the excessive value. Weather data for the days with C-14 emissions had been calculated that the precipitation must have taken place on the premises of the FRM II or in the immediate vicinity.
According to Görg, the C-14, which is used in archeology to determine the age of organic materials, has a half-life of 5730 years. At FRM II, it is produced in the form of carbon dioxide during a nuclear reaction in the reactor pool, which is also filled when the reactor is at a standstill. The incident occurred during the routine cleaning of the so-called heavy water there. The C-14 is bound via ion exchange resins, which then have to be dried.
An individual error in the assembly of the drying device caused the derivation of the C-14. After exceeding the values, all drying processes were stopped immediately. Process C-14 had already been released in 2012, but below the limit. Even then, the process had been improved, said spokeswoman Görg.
Many scientists are currently urgently waiting for the FRM II to restart, which is also one of the most powerful neutron sources worldwide for industry and medicine, said Görg. There have also been requests for research projects on the corona virus.
The FRM II is controversial because of the use of highly enriched uranium. Nuclear opponents, environmentalists and Greens have long criticized this and called for the shutdown, as this contradicts the operating license from 2003. You speak of weapons-grade material. There is currently progress in the search for a new, lower enriched fuel.
Last year there were civil protests and objections regarding the discharge of potentially weakly radioactive water into the Isar, which were discussed in a hearing with environmentalists, residents and authorities. No complaints were filed, however, the deadline had expired, said Görg.
Communication on the emission of radioactive C-14
