This lab exercise was developed for the UiO KJM 5911 course. The students will prepare a ion-exchange collumn using DOWEX-50 ion-exchange material and extract 234Th from a 234U solution. The thorium sticks to the ion exchanger and 1.17-min 234Pa will grow inn. The column can be milked once every 12 min. The students use 234Pa samples to measure its half life.
- To learn about radionuclide generators,
- working with short half lives,
- getting more training in handling radioactive material,
- learing about ion-exchange collumns.
Explanation and Exercise Guide
- 2 M HCl on 100 mL flasks, one for each student)
- DOWEX 50x4 (50-100 mesh)
- Uranyl nitrate - UO2(NO3)2
- NaAc + K4[Fe(CN)6] solution (on 100 mL flasks, one for each student) (prepared by mixing 8 g NaC2H3O2 and 40 g K4[Fe(CN)6] in 1 L water)
- 5% citric acid (on 100 mL flasks, one for each student)
- 0.1 M AgNO3 (on 50 mL flasks)
- Suitable columns which can be fitted with a stopper connected to a rubber ball so it can be pressurized (to quickly elute drops with short lived 234Pa from the column).
- Stop watches (one for each student)
- Sample holders to catch eluted drops from the colund and which can be mounted conveniently in the detector chamber
- Detectors - GM counters works well, but we have also used plastic scintillators mounted on PMTs and NaI-detectors. High efficiency is necessary to get god counting statistics even after the first 5-6 minutes.
- Chemical safety - nothing particulary dangerous, 2 M HCl and 0.1 M AgNO3 should of course be handled according to normal safety precations. DOWEX residues and waste should be collected and handled according to normal procedures.
- Rad. safety - very small amounts of uranyl nitrate is used, so rad. safety is mostly about regulations and not a real healt hazzard. Remember to collect the DOWEX from the ion-exchange collumns in separate containers as it is contaminated with 24-day 234Th (will be none-radioactive after one year).