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Compaction of radioactive hulls by high-temperature melting in a cold crucible

Obiettivo

The cold-crucible high-temperature melting process for compaction of cladding hulls has been developed in France by the CEA at Marcoule since 1982 under inactive conditions in a full-scale industrial prototype, and since 1988 under active conditions in a laboratory facility (Cell 73). This method reduces the waste volume and exchange surface area, and eliminates any occluded radioactive gases. Its feasibility has been demonstrated for conditioning radioactive stainless steel hulls. This research project involves compacting radioactive zircaloy cladding hulls in Cell 73.

The programme objectives are:

- to produce zircaloy ingots from radioactive hulls;
- to characterize the ingots;
- to determine the volatility balances;
- to assess the decontamination factor obtained.
The cold-crucible high temperature melting process for compaction of cladding hulls reduces the waste volume and exchange surface area, and eliminates any occluded radioactive gases. Its feasibility has been demonstrated for conditioning radioactive stainless steel hulls. This research project involves compacting radioactive zircaloy cladding hulls in a laboratory facility (Cell 73). The programme objectives are:
to produce zircaloy ingots from radioactive hulls;
to characterize the ingots;
to determine the volatility balances;
to assess the decontamination factor obtained.

3 zircaloy ingots were produced with a melting flux containing equal weight percentages of calcium fluoride and barium fluoride. Variable parameters included the flux percentage, the generator power, the ingot drawing rate and the chemical purity of the flux. Alpha decontamination was low, while beta decontamination was higher. Most of the caesium-137 was volatilized and trapped on the cold crucible head and in the particle separator; much of the strontium-90 was retained in the flux. Problems were encountered with tritium trapping.

3 active zircaloy ingots have been produced.
The activity partition between the flux and ingots has been determined for 2 ingots, and is still in progress for a third.
The process volatilization balance has been determined for 2 ingots.
Work programme:

- Production of four radioactive ingots in Cell 73 with zircaloy hulls from the Obrigheim reactor

- Investigation of the activity partition between the flux and ingot

- Characterization of two ingots:

- structural homogeneity
- internal activity distribution
- leaching resistance

- Determination of the process volatilization balance

Invito a presentare proposte

Data not available

Meccanismo di finanziamento

CSC - Cost-sharing contracts

Coordinatore

Commissariat à l'Energie Atomique (CEA)
Contributo UE
Nessun dato
Indirizzo
Centre d'Études Nucléaires de la Vallée du Rhône Cité de Marcoule
30205 Bagnols-sur-Cèze
Francia

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Costo totale
Nessun dato