Читать книгу Industrial and Medical Nuclear Accidents - Jean-Claude Amiard - Страница 56

The atmospheric emissions associated with the 1980 accident were estimated by EDF at 29.6 TBq in rare gases and 0.37 GBq in iodine and aerosols on the basis of the measurements made [IRS 15a].

Following the accident that occurred in March 1980 at one of the UNGG reactors in Saint-Laurent-des-Eaux, the fusion of two fuel elements from Unit 2 resulted in the release of a small quantity of plutoniums 239 and 240 into the Loire. This quantity was estimated at 10–20 mCi, or 535–740.10⁶ Bq, by Martin and Thomas ([MAR 88]). This represents between 0.063 and 0.322 g of ^239,240Pu [GUI 16].

Thomas ([THO 82]) measured Pu activities in sediments and suspended solids (SS) from the Loire. The results show that the ratio of ²³⁸Pu/^239.240Pu in particle matter is consistent with that of the overall deposition (about 0.05) upstream of the plants and in a single sandy sample taken downstream of the Dampierre plant, but this ratio reaches 0.15–0.42 downstream of St. Laurent. At the entrance to the estuary (Montjean), it is still 0.05–0.28 (Figure 2.4).

The IRSN [IRS 15a] states that the traces of the 1980 releases have no longer been perceptible in the Loire since 1994 and specifies that “the traces of plutonium measured in the soil as part of the monitoring near EDF’s nuclear sites are the result of the fallout from nuclear tests, with no discernible influence from releases from nuclear power plants”.

Figure 2.4. Isotopic composition of plutonium in sediments (full circles) and suspended solids (empty circles) in the Loire River between 1980 and 1983 [THO 82]. For a color version of the figure, see www.iste.co.uk/amiard/industrial.zip