RHONE-ALPES

At the Tricastin site, Comurhex produces uranium hexafluoride (UF6), chlorine trifluoride (ClF3), tungsten hexafluoride (WF6), compressed fluorine, and an F2/N2 mixture [Areva. Tricastin 07].  We present here only activities that involve uranium.

III.A. Plant for the conversion of UF4 and uranyl nitrate

The main portion of the plant, an ICPE, transforms UF4 from natural uranium into UF6; another section, INB 105, transformed uranyl nitrate from reprocessing into UF4 and UF6 or into U3O8 for storage.  According to M. Lemarchand, director of Comurhex, as of 1999, 95% of the uranium activity of Comurhex consisted in converting UF4 into UF6 from natural uranium and 5% in recycling uranium from reprocessing [CIGEET 27.ix.99].  INB 105 ceased operation at the end of 2008.

The separation of the two paths, natural uranium and reprocessed uranium, was not perfect.  According to DSIN, "the circulation of a compound for cleansing effluents in a part [of the plant] common to the two processes caused contamination of the fluorides sent to the Solérieux dump."  Comurhex made changes that allowed the flows from the two processes to be kept separate and resulted in  three types of fluorides:  those containing natural uranium; those containing reprocessed uranium; and those without uranium and  "susceptible of being reused (under development)" [DSIN 00].

III.A.1. L’ICPE

Period of operation: since 1962

Process: fluoridation in a flame reactor 

Raw materials: fluorine and, from Malvési, UF4

Nominal capacity: 14,000 t/yr of uranium

Actual production: en 2007, UF6 equivalent to 13,700 t of uranium

Commentary: Comurhex produces fluorine at the site by dissolving potassium fluoride in hydrofluoric acid and ionization of the solution

The UF4 is transformed into UF6 by fluoridation in a flame reactor. (See Production of UF6 in the section Refining and Conversion of Uranium Concentrates.)  

The gaseous effluents contain a little fluorine, nitrogen and UF6. The gases are treated in columns for washing, but the treatment is probably not 100% effective (see Romans).

A decontamination workshop responsible for cleaning parts to be altered releases liquid effluents contaminated with uranium and its descendents. The limit fixed is 50 mgU/l [SN v-vi.91].

The radionuclides that are not volatile, especially the descendents of uranium like thorium 230, radium 226, bismuth 212, and lead 214, "concentrate in the unburned material." They can be found on the walls of the reaction tube and in the filters [Level 71]. The unburned material and the filters that trap them are highly contaminated. In 1985, Comurhex packaged the dusts and the ashes from the filters in asphalt for the purpose of long-term storage [Beck 85].

In 1971 and probably still today, the gaseous effluents underwent a treatment that produced CO3K2 and calcium fluoride. The CO3K2 was reused and the calcium fluoride ("fluorine"), "lightly" contaminated with uranium, was put in a dump.

Between 1964 and 1977, Comurhex deposited 14,000 m3 of calcium fluoride, containing 1.4 t of uranium, in a mound within the Pierrelatte site (see Cogéma above). Between 1977 and 1995, it deposited 28,356 t of calcium fluoride containing about 1939 kg of natural uranium in metallic drums in the Solérieux dump [Andra 96]. In July ,1999, following controversy tied to the discovery of contamination of the fluoride that was dumped at Solérieux, Comurhex temporarily stopped the shipment of  fluoride to Solérieux (see Solérieux). The fluoride was contaminated with uranium from reprocessing. In November 1999, after Comurhex had remedied the problem causing the contamination, it restarted the shipments.

III.A.2. INB 105, AN INSTALLATION FORMERLY KNOWN AS THE ATELIERS PILOTES (PILOT WORKSHOPS)--SHUT DOWN

Purpose: transformation of uranyl nitrate into UF4 and then into UF6 for enrichment or into U3O8 for storage

Installations: structures 2000 (production of UF4 and U3O8) and 2450 (conversion of UF4 to UF6) [ASN 08]

Period of operation: structure 2000, 1976-2008; structure 2450, 1976-2002

Process: wet method (DUA); then flame reactor

Raw material: uranyl nitrate from reprocessing plants for light water reactor fuel, the uranium being enriched to 2.5% or less

Nominal capacity: 900 t/yr in the form of U308; 350 t/yr in the form of reprocessed uranium

Actual production: in 2007, 0 t of UF4 and UF6 and 537 t of U308; in 2008, 0 t of UF4 and UF6 and 6.2 t of U3O8 

Commentary:  any U308 that is produced has the same destination as the U308 from TU5

There is a reason for the name "Ateliers pilotes." For some time, Comurhex intended to construct a whole factory for the conversion of reprocessed uranium (the equivalent of Areva's TU5 installation). This plant would have been called INB 150.

The plants treated most of the uranyl nitrate from the reprocessing of light water reactor fuel at La Hague and at the DWK plant in Karlsruhe and they sent most of the UF6 to the United States for enrichment [NucE no. 1-2.88; Liégois 86; Durand 91].

In 2000, DSIN authorized the restart of structure 2000.  Its operation had been stopped until the flows of effluents that had contaminated fluorides with uranium from reprocessing had been separated [DSIN 00]. 

Comurhex stopped operating Structure 2450 in 2002. Structures 2000 and 2450 had previously handled compounds with 1%-2.5% uranium 235.  After Structure 2450 stopped operating, Structure 2000 handled only uranium enriched to less than 1%, which could allow the unit to operate under the regulations for an ICPE rather than an INB.  In a letter of December 8, 2004, Comurhex stated that it intended to stop operation of Structure 2000 and to shut down definitively the entire INB by December 2008 [ASN 05].  

In 2008 ASN discovered irregularities in the operation of INB 105, which could lead to chemical or radiological pollution; and it asked Comurhex for an action plan to correct the problems, in particular means of preventing tanks from spilling dangerous products.  Instead of producing a plan, Comurhex told ASN in October 2008 that it would stop operating INB 105 as of the end of the year.  During the first three months of 2009 Comurhex intended to submit a plan for dismantling INB 105 to ASN. Comurhex intends, however, to keep the chimney of INB 105 in operation, as the chimney collects gaseous effluents from most of its installations.  It will also keep certain open-air pads in operation [ASN 08].

The conversion of UF4 from the reprocessing of irradiated fuel into UF6 in a flame reactor partially purifies the reprocessed uranium. The destinations of the predominant impurities were as follows:

--transuranics: most of the transuranics are found in the unburned material or in the form of ashes. "Each kilogram of uranium releases activity equal to three or six times the annual limit of incorporation (LAI) of neptunium 237" [Castaing 81-82]. Nevertheless, sufficient transuranics remain in the UF6 to cause a problem during enrichment;

--fission products: the behavior of fission products depends on their vapor tension. The fluorides of ruthenium and technetium, which have around the same vapor tension as UF6, "are not completely separated" from the UF6 [Roux 88].

--the descendents of uranium 232: the wastes contain 95% of them;

--isotopes of uranium: all are in the UF6 where the uranium 232 generates new descendents.

The fluorides from washing residual gas (see ICPE above) are sent to Andra because they are too contaminated to be placed in a dump [Andra 96, 99, 00]. 

In 2007, as reported by Areva, gaseous releases of Comurhex from INB 105 (which consisted for the most part of gases actually created by the ICPE but sent to the INB for release) were 21 MBq of alpha activity from uranium, 30 MBq of beta activity from other radioelements, 644 TBq of tritium, 6.8 GBq of carbon 14, and 3296 kg of fluoride.  Releases of Comurhex from the ICPE  were 51 MBq of alpha activity from uranium, 35 MBq of beta activity from other radioelements, and 5.3 kg of fluoride [Areva Tricastin 07]. 

The liquid effluents are treated and controlled in installations belonging to INB 105.  They are then sent to Comurhex's ICPE workshops for the treatment of liquid effluents "for several last operations." Finally they are released into the Donzère-Mondragon canal via installations belonging to Cogéma/Areva [CogDem 01] (see Cogéma/Areva below).  The liquid radioactive releases of Comurhex in 2007, as given by Areva, are the following:  0.10 mg/liter or 0.77 kilograms of uranium; 6.5 mg/l or 49.5 kg of nitrogen; 1.01 mg/l or 7.8 kg of heavy metals;18 mg/l or 134 kg of fluorine; 0.79 TBq of tritium; and19.4 GBq of carbon 14 [Areva Tricastin 07]. 

Comurhex received authorization to reject liquid and gaseous effluents in a decree dated 17 August 2005 [JO 27.ix.05]. Decisions of ASN in regard to releases of tritium and carbon 14 [2007-DC-0079 and 2007-DC-0080] completed the authorization 4 December 2007.

III.B. Plant for the conversion of UF6 into UF4--shut down

Period of operation: 1968-?

Process: reduction of UF6 by hydrogen

Raw materials: UF6, usually depleted, from gaseous diffusion plants

The UF4 produced used to be sent to Malvesi to be transformed into metal [Level 76]. The manufacturing of metal at Malvesi was stopped in 1991. Thus the plant no longer operates [ArevaCom 08].  

III.C. Comurhex II

Areva announced in May 2007 that it will construct a new complex at Tricastin to convert UF4 to UF6.  Construction will  involve renovation of the existing Comurhex plant and creation of new installations[RGN.iii.06].  The new installations are 

--a unit for receiving, storing, and distributing HF (Unit 61); 

--a unit to produce fluorine by electrolysis (Unit 62); 

--a unit to receive, store, and distribute UF4 (unit 65); 

--a unit to transform UF4 into UF6 and to condition UF6 (Unit 64);

--a unit to treat liquid effluents (STEL) and to distribute potassium (unit 68).

The new installations will be built on the north end of the Comurhex site where INB 105 is now located.

Comurhex II will have an initial production capacity of 15,000 t of uranium per year, expandable to 21,000 t per year.  Site work, engineering, and permitting began in 2007 and civil engineering in 2008. The public inquiry on the project is being conducted in 2009.   Industrial production is expected to begin in mid-2013 [Areva. Tricastin. 07; Steyn 08;  ArevaCom 08].

                                                                                                                                                                                            --last entered May 28, 2009

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