radiation Flashcards
(30 cards)
how ionising is alpha radiation
highly ionising
how ionising is beta radiation
weakly ionising
how ionising is gamma radiation
very weakly ionising
what is the definition of ionisation
the loss or gain of electrons
what stops alpha radiation
few sheets of paper or few cm of air
what stops beta radiation
few m of air or few mm of aluminium
what stops gamma radiation
many km of air
few cm of lead
few m of concrete
what is the definition of activity
the rate of emission of radiation from a radioactive source
what is activity measured in
Bq
what are some sources of background radiation
rocks, soil, food
how does ionising radiation cause damage to living tissue?
it can destroy the cells entirely or damage the DNA in a way that causes the cells to replicate and grow uncontrollably- often called CANCER
absorbed dose is measured in?
Grays (Gy)
where do you get the weighing factor?
in the booklet
equivalent dose (H) is measured in?
sievert ( S)
.
H is?
the dose equivalent rate
what is the average annual background radiation in the UK?
2.2mSv
what is the Annual effective dose limit for members of the public
1mSv
what is the Annual effective dose limit for radiation workers
20mSv
what is a medical use of radiation?
radiotherapy- ionising gamma rays are used from outside the body to expose tissue and destroy cancerous cells.
what is half life?
the time taken for the activity to reduce to half of its original value
how to measure half life?
before the source is used the background count rate is measured using a Geiger Muller tube connected to a counter. the count rate from the source is then measured at regular fixed intervals over a period of time.
The background count rate is subtracted from each measurement of the count rate and so the actual count rate from the source is calculated
how do fission reactions work?
large nuclei are BROKEN apart when struck by a neutron. smaller fission fragments are created, INCLUDING more neutrons and ENERGY is released. The neutrons produced can be used to trigger further fission reactions causing a chain reaction
what happens if fission reactions aren’t controlled?
if the chain reaction is allowed to increase in an UNCONTROLLED manner all of the energy in the nuclear fuel will be RELEASED in an INSTANT- fission bomb
how to control fission reactions?
in a nuclear power station the majority of neutrons are absorbed by control rods, which maintain the chain reaction at a constants rate, ensuring the energy is released slowly
