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PRODUCTION OF RADIONUCLIDES (Production of Radionuclide the intentional…
PRODUCTION OF
RADIONUCLIDES
Formation of Radionuclide
the unintentional making of radionuclides.
Formed by:
Cosmogenic nuclear reactions in atmosphere
Thermonuclear fusion of nuclei at extreme temp
Production of Radionuclide
the intentional making of radionuclides
Produced by:
Synthesis of trans-uranium elements
Fission products and decays
Particle accelerators (Cyclotron)
Nuclear reactors (Neutron Irradiation)
Form of Radionuclides
1) Inorganic Compound
2) Labelled Organic Compound
Labelling
Radioactive labelled compound where at least one of the atoms are radioactive
Preparation to label may involved lengthy chemical synthesis starting with the radioactive nuclides in elementary form
Most synthesis of C-14 labelled organic compound follow conventional method with appropriate modification to contain the radioactivity
Method to Reduce the Surface Radiation Dose Rate (High Intensity Radiation Source)
1) Ampoule in the can
2) Can is put in a lead block
3) Packed in a wooden crate (for transportation)
Radiochemical Processing
It took long process between the removal of irradiated target from the irradiation facility because separation process is needed to make pure radiation source are chemically the same and independent of the size.
Purification Techniques
Precipitation
Ion Exchange
Solvent Extraction
Electrodeposition
Electrophoresis
Distillation
Purpose
: to eliminate radioactive contamination and avoiding diluting the radionuclide by isotope stable atoms
Radiochemical Purifications
very crucial because several radionuclides of different elements present in a tracer sample used in an experiment, the result may be ambiguous and misleading
Radioisotopic purity of a sample may be ascertained by measuring the half-life
This method obviously can be used only with radionuclide that show sufficient decay during the time of observation for a reliable half-life to be calculated.
Radionuclide of high specific activity produced by:
1) Accelerator Irradiation
2) Secondary Reaction in the target in reactor
Determining the Mode of Production
Determination Factors
1) The availability of accelerators or reactors
2) The availability of target nuclei
3) Duration of production
4) Separation and purification processes
5) Time interval between production and shipping
6) Reaction cross-section
Target Considerations
Simple tracer experiment
For a product of extreme purity, very high specific activity and very short half-life, special techniques are used
Properties of Target
Physical
Target is thin with a surface weight not more than a few mg/cm2
The flux and energy of the projectile do not change during passage through the target
usually used in accelerator irradiations and are made of a solid material either metal or compound
In order to have sufficient mechanical strength the target is usually supported on a backing material.
Thin targets are fixed on the backing material through:
Electrolytic Precipitation
Vacuum Deposition
Mass Spectrometric Collection
Chemical
An extremely pure target can be used with a reaction path.
The radioactive products can be purified after the end of the bombardment
Organic compounds are not stable towards either neutron or charged particle bombardment.
Simple inorganic compounds like NaCl are stable
The products have to be transferred fast and continuously to the chemical separation system.