Boron isotopes enrichment via continuous annular chromatography

Abstract

Boron has two stable isotopes namely 10B and 11B isotopes. The large cross section of 10B isotope for thermal neutrons is used for reactor control in nuclear fission reactors. The thermal neutrons absorption cross sections of pure 10B and 11B are 3837 and 0.005 barns respectively. In the literature, amongst others, batch elution chromatography techniques are reported for 10B isotope enrichment. This work focuses on continuous chromatographic 10B isotope separation system via continuous annular chromatography (CAC) where isotope enrichment from boric acid solution is studied. CAC is slurry packed with commercially available n-methyl glucamine functionalized boron-specific anion exchange resin (Diaion CRB03 - Mitsubishi). The nominal height of AISI 316 stainless steel pipe outer and inner cylinders of CAC is 200 cm. The outside diameter of column is 20 cm and inside diameter of inner column is 14 cm. The liquid level above the top of the resin is monitored with an ultrasonic sensor. Its level is kept between the set values by air injection from the top of the column. For this purpose, the liquid level signals received from the ultrasonic sensor is fed to a proportional controller unit so as to adjust the column head pressure by regulating air injection pressure and its flow rate. Dilute aqueous nitric acid solutions were used as the eluent. Eluent 10B and 11B isotope ratios are measured by ICP-MS spectrometer (Perkin Elmer, ELAN 9000). It is determined that depending on the operation parameters 10B isotope ratio can be increased over 27% in a single pass mode operation of the present CAC apparatus