The Institute for Radiation Protection and Nuclear Safety (IRSN), which continues its investigation, said Thursday that the abnormal level of tritium measured in the Loire this year is likely related to a sampling methodology problem.
Power plants have the right to reject tritium
The Association for the Control of Radioactivity in the West (ACRO) announced in June, after a measurement campaign, a high level of tritium (radioactive isotope of hydrogen), particularly in Saumur. Reviewing its investigations in an information note, the IRSN considered "unlikely" that this is an incident in the discharge process of EDF's nuclear power plants, which are several along the the Loire. Power plants have the right to reject tritium within the limits set by the authorities.
The hypothesis of a rejection by a source other than EDF is for its part "difficult to consolidate". Experts believe that a "problem with the sampling methodology" is "the most likely hypothesis". More specifically, the most likely cause lies in sampling outside the so-called "good mixing" zone, that is to say in which the tritium concentration is homogeneous.
New measurement campaign
"At the time of detection by ACRO of the peak concentration in Saumur, the main source of discrepancy between the measurement resulting from regular monitoring and the model would be attributable mainly to a delay in the homogenisation of releases from the central of Chinon ", indicates the IRSN.
The institute intends to continue its investigation, with the Nuclear Safety Authority (ASN), by launching a new measurement campaign under conditions "as close as possible" to those that led to the measurement of ACRO in Saumur (in winter, in a period of low water).