Cedo Module Q Flashcards
Cedo cinde course (94 cards)
Five types of radiation monitoring devices
1- survey meter 2- direct reading dosimeter (drd) 3- thermoluminescent dosimeter (tld) 4- optically stimulated luminescence dosimeter (osl) 5- Alarming dosimeter
Survey meter must measure how many sieverts and what are the requirements
20 micro siverts/hour to 100 million siverts/hour. It must have a battery check function and be calibrated within the last 12 months.
Advantages and disadvantages Advantages to the direct reading dosimeter
Advantages: robust and low maintenance, small and clips clothing (pen shaped), weather proof, easily read by user
Disadvantages: limit rang usually less 5 milli sieverts, no permanent record, it can give false readings if dropped.
When did the use of the thermoluminescent dosimeter begin and when did it start phasing out.
It’s been used since 1976 and phased out in 2009
How does the thermoluminescent dosimeter work
It uses lithium fluoride chip which is used to store electrons displaced by radiation. The chips are read at the national dosimtry service
How does the optically stimulated luminescence dosimeter work. when was it put in use
It started in 2009. It contains sensitive elements that absorbed radiation and store some of the energy in the form of excited electrons. When received at the national dosimetry service. Sensitive elements are stimulated using light emitting diodes.
Equation for finding number of neutrons
Mass number(A) minus Atomic number(Z)= number of Neutrons(N)
Units for activity are?
Curi(Ci) and becquerel(Bq)
Specific activity is measured in?
Curi’s (Ci) per gram or Becquerel (Bq) per gram
What does an atom consist of
A nucleus consisting of protons(+) and neutrons and orbiting electrons(-1)
What does one curi (Ci) equally in becquerel (Bq)
1 (Ci)= 37 giga (Bq)
What is characteristic intensity and what is it measured by
It is measured by Reontgens per hour. Old system is measured by milli Rankin per hour@ 1 meter. New SI system milli siverts per hour@ 1 meter.
Equation for intensity
Intensity= Source Activity× Characteristic Intensity( see table 1)
What is radiation absorbed dose measured in
In the previous system units are measured in RAD (radiation absorbed dose) in the SI system its measured in Gray (Gy)
What is the conversion from RAD to Gray
1 Rad= 10 milli Gy
1 Gray= 100 Rads
What is the penetration capability for each form of radio active decay
1) Alpha rays- stop at paper
2) Beta ray’s- stop at thin board such as aluminum
3) Gamma and x rays- stop at thick board such as lead
4) Neutron rays- Stop at water concrete
How are industrial isotopes created
By placing elements in a nuclear reactor they gain one additional neutron. They become unstable and start the decay process releasing radiation.
What is the units for does equivalent
The previous system it was Reontgen equivalent man (REM). In the SI system it is referred to as Sieverts (Sv).
What is the Equation for Dose Equivalent and conversion
REM= Rad×QF
Sievert= Gray×QF
1 sievert= 100 REM
What is half life?
Half life is the time taken by specific isotope for the activity to decay to one Half its original value.
What’s is the half life for iridium 192, cobalt 60, and selenium 75
Iridium 192- 74 days
Cobalt 60- 5.3 years
Selenium 75- 120 days
What is the equation for determining half life and remaining activity
A2= A1÷2 to the power of n
A1- original activity
A2- new activity
N- number of half-lives
When must an Alarming dosimeter be used. when should it alarm at and how often should it be calibrated
Must be used when using gamma radiation. It must alarm at 5 milli sieverts per hour or when the total dose reaches 2 milli sieverts. It must be calibrated within 12 months.
When do you use the log symbol for calculating half life’s
When you have both values of activity before and after the decay and you want to find how many half life’s used. Simply sub a2 for n. Find the answer and log it by 2