(Includes: A, B, G, protons, neutrons & Xrays)
Ionising Radiation hazardous because it damages living cells by:
- Destroying Cell membranes; killing the cells.
- Damaging vital molecules (i.e. DNA) directly.
- Damaging indirectly by producing 'Free radical ions' which react with vital molecules, which damages cell nuclei and causes uncontrollable cell division& growth which is the cause of tumors that could be cancerous. (Somatic effect)
- (Genetic effect): damaged DNA in sex cells can cause mutations that could be inherited in future generations.
- People who use equiptment that produces ionising radiation must wear a film badge to monitor exposure.
- Exposure to each form of ionisation is then estimated from the blackening of the film when developed.
Dose and Limits...
- Biological effects from ionising radiation depend on the dose; which is measured in terms of energy absorbed per unit mass of matter from the radiation.
- The same dose of two different types of ionising radiation (A, B, G etc...) have different effects.
- 'A' radiation produces more ions per millimeter than 'G' in the same substances so is more damaging BUT 'A' radiation from a source outside of the body can't penetrate skin so less damage than if it were inside the body.
- Every dose has a dose equivilent in Sieverts (Sv), which is the dose due to 250KV Xrays that would have the same effect: 1mSv of 'a'has the same biological effect as 10mSv of 250KV Xrays.
- Maximum permissible exposure limit for annual dose equivilent: recommended limit is 15mSv.
- Average dose of equivilent for a radiation worker is 2mSv.
Occurs naturally due to:
(Descending in average radiation per year)
- Air (radon gases etc...)
- Medical uses
- Ground & Buildings
- Food & Drink
- Cosmic Rays
- Nuclear Weapons
- Air Travel
- Nuclear Power
And varies with respect to geography (Geological features!)
Safe use of Radioactive Materials
- Lead lined containers- Most sources produce gamma radiation aswell as Alpha & Beta, so lining must be thick enough to reduce Gamma radiation to roughly background level.
- Regulations require containers to be kept under 'lock & key'.
2.Using Radioactive Material:
- No source can come into contact with skin
- should be transfered using handling tools (robots, long tongs, glove boxes), so the source is ALARA (As low as reasonably achievable)
- Liquid, gas & powders are kept in sealed containers, so radioactive gas can't be inhaled; liquid can't be spashed or drunk.
- Radioactive sources shouldn't be used beyond necessity- more exposure= greater dose recieved.