See glossary pages 33 to 36 Plutonium discharges into the river Loire According to the chairman of the NPP surveillance committee: “Once everything had cooled down, a few kilograms of uranium had melted and been deposited in the bottom of the reactor pressure vessel. These materials were loaded with fission products and plutonium. During the clean-up, a rinsing operation was carried out and liquid discharges were washed into the river Loire”. The NPP stated that it “had observed the regulatory discharge authorisation limits applicable at the time, set by the Ministerial Order of June 1979”. On 4 May 2015, a documentary entitled “Nuclear power, the policy of lying?”, broadcast by the French television channel Canal+, stated that following this accident, EDF made totally illegal discharges of plutonium into the river Loire for a period of at least five years. A sampling campaign of sediments in the Loire conducted by a university laboratory established the presence of traces of plutonium extending from Saint-Laurent-desEaux to the estuary, the origin of which could be attributed to either the accident of 1980 or that of 1969 (see above). In IRSN’s opinion, the majority of these traces were not linked to the accident of 13 March 1980 but to the treatment of water from the reactor A2 pool, which was contaminated when a container enclosing an unsealed fuel element burst on 21 April 1980. Based on the dosimetric evaluations carried out using the estimated activity discharged at the time, IRSN considers that the plutonium discharges into the river Loire remained sufficiently low for the health and environmental risks downstream of the site to be considered negligible. Saint-Laurent-des-Eaux, two accidents in France Core sampling technique for taking and analysing sediments from river banks. Steps in the analysis of a sediment on the banks of the river Loire 1. Identification of the best core-sampling site, defined by a multidisciplinary team (geochemists, hydrologists, etc.). 2. Taking of sediment samples at two different depths every metre. 3. Gamma spectrometry analysis of the samples in the laboratory. The tubes are cut in the longitudinal direction and opened. The excess caesium-137 and lead-210 are measured in each section to date them. 4. The radionuclides are analysed in an IRSN laboratory. An expert looks for the plutonium, carbon-14 and organically-bound tritium. The analysis revealed peaks of plutonium in the years 1969 and 1980, which correspond to the two accidents that occurred at the Saint-Laurent-des-Eaux NPP. “We must preserve the memory of those who founded ASN and the various organisations that preceded it. Today we are still treading the path towards ever-greater independence and transparency.” Philippe Saint Raymond Deputy Director of Nuclear Installations Safety (1993 – 2002), then Deputy Director-General of Nuclear Safety and Radiation Protection (start of 2002 to February 2004) 10 • Les cahiers Histoire de l’ASN • November 2023
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