Outcome 5 Flashcards
What is the purpose of the radiation safety manual?
- it provides written communication to outline radiation safety procedures and the limits
- this proves to CNSC that proper radiation protection program is being followed
What are the requirements of a radiation safety manual?
- has to be accessible to workers
- prepared, updated and revised by RSO
- must be approved by senior management
What can be found in the radiation safety manual? (Table of contents)
- alara policy
- action levels
- worker training/authorization
- designation of nuclear workers
- designation, posting and decommissioning of rooms and access
- control of nuclear substances
- procedures for radioactive waste handling and disposal (receiving, transporting and packaging)
- radioactive contamination control and procedures
- maintenance and use of radiation detection equipment
- emergency procedures
- records and reporting systems
What are action levels?
- specific dose of radiation, that if reached, may indicate a loss of control of a part of a licensee’s radiation protection program—triggers a requirement for a specific action to take place
How are action levels developed?
- developed when applying for a license
- developed using historical data (or reference from a comparable facility
- must be useful and credible
- supported by a monitoring program
What are some examples of action levels?
- ambient dose rate
- loading or concentration
- individual quantity of radiation received
- ventilation rates
- emission/discharge rate
- surface contamination
What happens when an action level is reached?
- investigations to find out why
- identify and take action to restore effectiveness of the radiation protection program
- notify commission within period specified on the license (within 21 days)
What are Action Levels at SAIT?
- Ambient dose rate = ______
- contamination monitoring = _______
- dose limits = _______
- hand monitoring = _______
- Ambient dose rate = 1 uSv/hr above background
-Contamination monitoring - class a: 0.3 Bq/cm^2
class b: 3 Bq/cm^2
class c: 30 Bq/cm^2 - dose limits = instructors - 1 mSv/yr; students - 0.5 mSv/6 months or 1 mSv/yr
- hand monitoring = >background
When are action levels not needed?
- when you can prove to the CNSC that your occupational doses are unlikely to exceed 1 mSv/yr
- when the dose to the public is unlikely to exceed 50 uSv/yr
- the annual collective dose (occ. + public) is unlikely to exceed 1 Sv
What is an example of an action level for a NEW’s EDL?
1 mSv/yr
When you inform a worker of their NEW status, what does that mean?
- that they will be working with radiation
- you have to let them know the risks associated with it/possible exposures
- what their effective dose limits would be
- what typical dose levels of NEW in that area are
- what their rights and obligations are (pregnant NEW)
How long are proof of adequate training records kept for?
3 years in the employee’s file after termination
What are basic training course topics are required?
- intro to radiation and its sources
- fundamentals of radiation
- personal and survey meters
- radiation exposure
- radiation protection
- radiation safety program
What are some additional training that a NEW can have?
- TDG
- WHMIS certification
- RSO training
When are personnel radiation dose monitoring required?
When there is a reasonable probability of the NEW receiving an effective dose greater than 5 mSv in a one year dosimetry period
how do you monitoring external doses received? internal doses?
external - personal dosimeters (CNSC certified = TLD and OSLD)
internal - thyroid screening and bioassay programs
What shouldn’t you expose your dosimeter to?
- high temperatures
- water
- direct sunlight or fluorescent light
How do you properly wear your dosimeter? extremity dosimeters?
between your neck and waist area
extremity dosimeters - worn facing the source of radiation
How do temporary dosimeters work?
they are typically for visitors/temporary personnel
- readings are taken before and after
When are personal external exposure dosimeters exchanged? why?
quarterly – this is because we want to know sooner than later what our received dosage is
What kind of style of OSLD/TLD is used for whole body and skin dose readings?
badge style
When are finger/ring dosimeters used?
if more than 50 MBq of high energy BETA sources are handled
What is the difference between TLD and OSLD?
What happens in the dosimeters?
TLD - requires heat to release the electron
OSLD - requires light energy
when the electron drops back to stable state, it’ll give off light, which is what is being read – this will tell us how much dose was absorbed
What is the standard curve?
total area under the glow curve vs. standard absorbed doses
what is the glow curve?
the area under the curve that is given by the absorbed dose of the dosimeter
What are some examples of temporary/short-term use dosimeters?
- electronic dosimeter
- direct ion storage dosimeter
What is the difference between the two examples of temporary dosimeters? what are the similarities?
electronic - silicon semiconductor detectors; more expensive; can measure x, gamma and beta
direct ion storage - has a miniature ion chamber that absorbs charges; less expensive
electronic and direct ion - immediate readout, + both are good for emergency, high risk activities, and pregnancy
You must wear your dosimeter whenever you’re working in a controlled area. T/F
True.
What are considered controlled areas that you need to be wearing your dosimeter during?
when working with x-ray equipment, working with radioactive patients and materials
How do you know what the lead aprons are going to do what its supposed to do? how often is this done?
sending them to x-ray to see if there’s any cracks
once a year
When is thyroid screening done?
after the use of volatile radioactive iodine
What is the ALI for I-125? I-131?
I-125 = 1 MBq/yr
I-131 = 1 MBq/yr
What amount of iodine used is required for thyroid monitoring on an open bench? in a fume hood? in a glove box?
open bench - 2 MBq
fume hood - 200 MBq
glove box - 20,000 MBq
When does thyroid screening need to be done?
1-5 days after each use or 2-24 hours after an incident
What is the thyroid screening procedure?
- using the Nal(Tl) uptake probe (with sensitivity of 1kBq)
- take background count
- position probe in front of technologist at a standard distance and take a neck count (usually ~ 3 minutes)
- compare to eval requirements for screening results outlined by CNSC
What are the CNSC eval requirements for thyroid screening to be confirmed? Investigation level? Reporting level?
To be confirmed - if any reading is >= 1 kBq
Investigation - >= 1kBq and < 10 kBq
Reporting - >= 10 kBq
Is personnel hand monitoring regulated by CNSC?
No.
Why is hand monitoring important?
To prevent internal contamination and area contamination by monitoring work practices; alara practice!
