Purpose/type: plants for treating ore and refining and converting uranium

Installations: uranium plant; thorium plant

Location: an enclave, originally 6 ha, within the Bouchet powdery at Vert-le-Petit (Essonne) south of Paris

Operator: CEA

Period of operation: 1946-1971

Raw materials: ore and uranium concentrates, uranothorianite

Nominal capacity: since 1958, about 500 t/yr of uranium metal (plus other products)

Actual production: more than 4000 t of uranium metal, 2892 t of thorium

Commentary: The CEA rented the buildings from the Direction des Poudres. In 1961 the Bouchet plant became the Bouchet center.

In 1948, 8 t of uranium oxide and 9 t of uranate of sulfur from Belgium were purified to produce UO2 fuel for Zoé. In November 1949, the CEA succeeded in extracting the first milligram of French plutonium.

From 1949 to approximately the end of 1956, Le Bouchet received high quality uranium ore (2-10% or more uranium) to concentrate and refine [Goldschmidt 56; Decrop 58]. After 1956 the CEA used poorer ore and, as a result, treatment plants were built near the mines. After early 1958 le Bouchet received scarcely any raw ore. At the rate of 10-20 t/d of ore, Le Bouchet treated about 9500 t of ore in total, if all the residues are stored today, as Cogéma and Andra indicate, at Bessines.

Wastes from the concentration and refining are today found, according to Andra, at Bessines, Sepa zone (untreated ore); at Brugeaud and at Lavaugrasse (tailings); and at the Le Bouchet annex (waste rock).

Le Bouchet produced its first ton of uranium metal in 1949. The production capacity increased until 1958. In 1958 the capacity stabilized at 500 t/yr [Decrop 58].

Le Bouchet produced more than 4000 t of natural uranium metal, for research reactors and UNGG reactors in particular. In 1969 and 1970 the plant produced in total 159 t of depleted uranium metal, probably from uranyl nitrate provided by La Hague. The plant also fabricated “half-finished” products, including UF4 for conversion to UF6 at Pierrelatte.

In addition, the recovery workshop and the grilling workshop reprocessed waste coming from other establishments includes the factories of Annecy and of Romans as well as that of the Le Bouchet site itself.

The plant’s wastes included:

--Atmospheric effluents. The most significant releases were in all probability particles of uranium oxide coming from grilling in the open air.

--Liquid effluents. The main effluent was the solution from the purification workshop in the uranium refining chain. The effluent was treated and, containing still a little uranium and impurities from concentrates, was transported as sludge to the decantation basin.

--Solid wastes. They included sludges from treating effluents, filters, etc. [Délange 64].

Operated from 1957-1971, the plant was located in “a major expansion” of the original enclave. It received uranothorianite from Madagascar, already concentrated by washing in that country. The ore contained uranium and thorium 232 in various proportions.

The installation used several procedures, including a procedure for separation of uranium and thorium by selective extraction at the same time as the purification proper. The thorium was recovered in the form of nitrate that was nuclearly pure, and uranium in the form of sodium uranate x.

The CEA estimated in 1967 that the plant would treat in total 5400 t of physical concentrates to obtain 935t of uranium and 2892 t of thorium [CEARa 67].

Uranothorianite is much more radioactive than the uranium and thorium ore that is normally treated. The activity on contact with a 60 l container holding uranothorianite amounts to 2.96 GBq/h.

Wastes from the factory include:

--Atmospheric effluents. A system of filtration and activated carbon would stop gases such as radium and thorium, “at least in great part.”

--Liquid effluents. To obtain radium at the feet of extraction columns, lead sulfate was precipitated. The uranium followed the lead. After neutralization and filtration, the liquid that remained was released into the river, along with a little radium; and also, after dilution, the mother-liquid from the filtration of uranate and of thorium hydroxyde [Braun 1958]. The river, it seems was the Juine [BIST ii.64].

--Solid wastes. The tailings (5600 t) are at Bauzot; the empty casks, crushed, at Fanay; and about 3 t of untreated uranothorianite at Bessines-Sepa. A portion of the irradiating lead sulfate, formerly stored at the CSM, have recently been repackaged and transferred to Cadarache. At Razes is found a radon generator made of 57 drums of lead sulfate, each weighing about 110 kg.

The annex of Le Bouchet at Itteville (Essonne), a former waste dump, was used by the CEA between 1948 and 1971 as a decantation basin and storage yard. In 1999 there remain on the site 15,000 t of sludge containing 20 t of uranium and 1 t of thorium, 8000 t of rubble, 2100 t of waste rock, and 2500 t of hydroxides. In conformity with a decree by the prefect, the CEA covered the site in 1993 with compacted clay, gravel, and earth [Andra 99; Echo 3.i.92; Libé 5.vi.92]. A study by researchers from IPSN has found that the rehabilitation reduced the concentrations of radon 220 and radon 222 to those found elsewhere in the Paris region [Robé 96].

Cen Saclay was responsible for the project. The CEA gave back the property to the Société nationale des poudres et explosifs en 1979 [Lallement 91]. L’Andra recognizes the following wastes: 1900 t of scrap metal (Brugeauds) and 61,555 t and 2200 m3 of earth and rubble (Brugeauds, Montboucher, the site of Le Bouchet at Itteville, filling in of the autoroute at Chilly Mazarin).