Developed By

Tor Bjørnstad
Section of Radiochemistry
Institute of Chemistry
Faculty of Mathematics and Natural sciences
University of Oslo

Learning Goals

• Understand mother-daughter relations and radioactive equilibrium
• Understand how a radio-nuclide generator works and how it is used
• Understand how radioactivity is "growing in"
• Training in handling radioactive material and safety procedures

The task in this Laboratory Exercise is to record a disintegration curve of 234mPa and from this curve determine the half-life of the nuclide. The234mPa radionuclide is obtained from a generator system consisting of an ion exchanger column with fixed 234Th where the daughter is milked by a liquid elution process. The α particles from the produced 234mPa-source is recorded by a GM-detector.

Explanation and Exercise Guide

Theory

Principle Behind Mother-Daughter Relationship

Experimental Procedure

Production and Measurement of a 234mPa Nuclide Generator

Questions for the Students

Safety Aspects

• Chemical safety - nothing particularly dangerous, 1 M HCl and 0.1 M AgNO3should of course be handled according to normal safety precautions. 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 health hazard. Remember to collect the DOWEX from the ion-exchange columns in separate containers as it is contaminated with 24-day 234Th (will be none-radioactive after one year).

Equipment

• HCl (MSDS) on 100 mL flasks, one for each student)
• DOWEX 50x4 (MSDS) (50-100 mesh)
• Uranyl Nitrate (MSDS) - UO2(NO3)2
• NaAc (MSDS) + K4[Fe(CN)6]] (MSDS) 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)
• 10% citric acid (MSDS) (on 100 mL flasks, one for each student)
• 0.1 M AgNO3 (MSDS) (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 column 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 good counting statistics even after the first 5-6 minutes.

Preparation for the lab Supervisor

The equipment needed should be ready. The solutions needed should also be prepared. It is usually a good idea to not use to large columns as the time needed for the solution to pas trough the dowex will increase quite a lot with increased volume.

Feedback from Users and Supervisors

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