Radiation Flashcards
What is an isotope?
a nuclide with the same number of electrons and protons but different numbers of neutrons
what is the difference between a cation and an anion?
Cation - positively charged species
Anion - negatively charged species
What is a radionuclide?
an unstable nuclide that emits ionising radiation
What is ionising radiation?
radiation that causes ionisation in matter. e.g alpha, beta gamma etc
What is radiotoxicity?
The effect of radio isotopes becoming bound in the body and producing intense biological harm as they decay.
What are the 4 types of decay?
Alpha - 2 protons and 2 neutrons emitted by a radionuclide, cant penetrate the skin.
Beta - release of a +/- electron from the nucleus of a radionuclide, may penetrate the skin but stopped by a few mm of metal
Gamma ray - a discrete quantity of electromagnetic energy, without mass or charge, emitted by radionuclide, cannot penetrate lead/thick concrete.
X-ray - a discrete quantity of electromagnetic radiation, without mass or charge, emitted from an x ray machine.
What is a Bacquerel (Bq)?
The standard international unit of radiation, corresponding to one nuclear disintegration per second.
What is a Gray (Gy)
The standard unit of absorbed dose, corresponding to joule per kilogram of material.
What is a Sievert (Sv)
Standard unit of biologically effective dose (absorbed dose (Gy) * biological effectiveness of radiation)
What is the absorbed dose?
The quantity of energy imparted by ionising radiation to unit quantity of matter, such as tissue (Gy)
What is the dose equivalent?
Absorbed dose weighted for harmfulness of different radiations (Sv)
What is the effective dose equivalent?
dose equivalent weighted for the succeptibility to harm of different tissues. (Sv)
What is the collective effective dose equivalent?
the effective dose equivalent to a group from a source of radiation (man Sv)
Where does radiation in the UK come from?
Natural causes account for 85% - 50% of which is Radon. The remaining is food and drink, cosmic and gamma.
Artificial includes - Nuclear fall out and discharges, consumer products, occupation, medical
what are the effects of Radon?
In open air Radon gas is dispersed, indoors it breaks down into minute solid particles which when breathed into the lungs can increase the risk of lung cancer - 5% of cases in the UK.
According to UK law what is the acceptable average annual dose of artificial radiation?
< 1 mSv
What is radon and where are the natural sources of Radon?
Radon is a radioactive gas released from the ground. It is found in high concentrations in Cornwall, Devon and Somerset etc due to the geology of the areas.
Indoor concentrations are accepted up to 200 Bq/m3, above which action is required. Averages = 1.3 mSv
What is the average annual dose from natural gamma radiation.?
0.35 mSv
What is the average annual dose from food and drink?
0.27 mSv
Which food types have high radiation levels.
People who eat a large quantity of shellfish are exposed to 220Po radionuclides, along with those who eat large quantity’s of Brazil nuts which have a high proportion of 226/228Ra.
What is the average annual dose from cosmic radiation?
0.32 mSv
What may effect the dose of cosmic radiation?
The amount of time spent flying increases the exposure to cosmic radiation with pilots being the most at risk.
Buildings provide partial shielding resulting in those who spend a lot of time indoors being least effected.
What are the artificial sources of radiation?
Medical - x rays, radionuclides, chemotherapy
Occupation - those who work in mine and nuclear related industries may absorb higher dose.
Fall out - nuclear weapon testing 1960’s, Chernobyl accident 1986
Consumer products - smoke detectors,gas mantles (thromium), watches (tritium)
Nuclear discharge - industries using radioactive materials, water effluents/air emissions
How has nuclear fall out trends fallen over time?
the annual dose was very low before 1960, however due to nuclear weapon tests in the 1960’s the dose rose to 0.14 mSv in 1963. Here after a PARTIAL NUCLEAR TEST BAN TREATY was signed and the annual dose fell to 0.0006 mSv in 1985. The 1986 Chernobyl accident resulted in a sudden spike. levels have fallen since then.
