IRR (lecture 1) Flashcards
What are the general principles of radiation protection?
Justification, Optimisation and Dose limitation
To what do the Ionising Radiations Regulations apply, and who enforces them?
IRR (2017) applies to work activities and exposures to staff and public. They are enforced by the Health and Safety Executive (HSE).
Who does the ultimate responsibility for radiation protection lie with, according to IRR’17?
The Employer
What are the dose limits on effective dose for employees older than 18?
20mSv
What are the dose limits on effective dose for trainees younger than 18?
6mSv
What are the dose limits on effective dose for “other persons”?
1mSv
What are the dose limits on equivalent dose per year to the lens of the eye for employees over 18?
20mSv
What are the dose limits on equivalent dose per year to the lens of the eye for trainees under 18?
15mSv
What are the limits on equivalent dose per calendar year to skin averaged over 1cm2 & extremities for employees over 18?
500mSv
What are the limits on equivalent dose per calendar year to skin averaged over 1cm2 & extremities for trainees under 18?
150mSv
What are the limits on equivalent dose per calendar year to skin averaged over 1cm2 & extremities for other persons?
50mSv
What is the ICRP recommendation for pregnant workers?
Once the pregnancy has been declared a limit (equivalent dose) of 2mSv to the surface of the abdomen is applied for the rest of the pregnancy. This implies a dose of ~1mSv to the foetus.
When should someone be registered as a classified worker?
Workers who MAY receive an effective dose of >20mSv in a several minutes.
Anyone who receives more than 3/10 of any dose limit (such as >15mSv equivalent to the lens of the eye, or >6mSv effective).
What are the three main values used to assess area designation based upon dose?
IDR, TADR, TADR2000
What is IDR?
Instantaneous dose rate averaged over 1 minute
What is TADR?
Time averaged dose rate averaged over 8 hours assuming an occupancy of 100%
What is TADR2000?
Time averaged dose rate averaged over a 2000 hour working year taking into account occupancy, use, and workload
What are the guideline dose-rates for designation of a controlled area?
IDR>100 (guidance),
TADR>7.5 (ACOP),
TADR2000>3 (equiv. to 1mSv/year)
All in micro Sieverts/hour
What are the guideline dose-rates for designation of a supervised area?
IDR>7.5, TADR>2.5, TADR2000>0.5
micro Sieverts/hour
What are the guideline dose-rates for designation of an unsupervised public area?
IDR<7.5,
TADR<0.5,
TADR2000<0.15
All doses in micro Sieverts/hour
What should the entrances to controlled areas be marked with? (3)
Warning notice, radiation trefoil, illuminated warning light.
Other than signage, what physical and procedural measures should be in place in relation to the designation of a controlled area? (3/4)
Systems of work, boundaries (confirmed with environmental monitoring), environmental and personal monitoring to ensure non-classified workers don’t exceed any classification levels.
What are the responsibilities of an RPA? (4)
Giving advice on radiation safety such as;
area designation
new installations
calibration and proper use of monitoring equipment
periodic testing of control and safety features
What are the dose limits on equivalent dose per year to the lens of the eye for other persons?
15mSv
