Basic Radiation Protection Office Radiation Protection Office Radioactivity
Basic Radiation Protection Office
Radiation Protection Office
Radioactivity Nuclide – a particular atomic nucleus with a specific number of protons (p) and neutrons (n). For example 31 P 32 P 33 P Approximately 1700 known nuclides. About 1400 are unstable – RADIONUCLIDES. Radionuclides - imbalanced numbers of p and n. - emit particles/energy to improve stability Radiation Protection Office
Radioactivity Gamma photon Radionuclide Dis int eg rat ion Charged particle Excited daughter Excess energy Stable daughter Radiation Protection Office
Sources SEALED – a radioactive source containing radioactive material where the structure is designed to prevent, under normal use, any dispersion of radioactive substances e. g. Am/Be sealed in stainless steel capsule UNSEALED - dispersible Solids – powders Liquids – aqueous or organic Gases – e. g. Xe-133 MACHINES – e. g. x-ray and neutron generators Radiation Protection Office
Main Emissions Alpha (a) Beta (b) Gamma (g) Helium nuclei (2 p + 2 n) + 2 positive charge 4 mass units High speed electrons -1 negative charge 0. 0005 mass unit Electromagnetic photons No charge No mass Radiation Protection Office
Energy of emissions Þ ELECTRONVOLTS (e. V) 1 e. V = energy gained by an electron passing through an electrical potential of 1 volt 1 e. V is a very small energy = 1. 6 x 10 -19 joules. Normally emission energies are in ke. V or Me. V range. Radiation Protection Office
Ranges Particle Alpha Beta H 3 C 14 P 32 Gamma Energy (Me. V) Range 3 -7 Tissue Air < 1 mm few cm 0. 018 0. 156 1. 70 0. 1 – 0. 6 0. 05 mm 0. 3 mm 8 mm V. Large 4 mm 2 cm 600 cm V. Large Radiation Protection Office
Activity (A) Rate of disintegrations in a large group of nuclei. A(t) µ N(t) which means EXPONENTIAL DECAY. SI unit is BECQUEREL (Bq) 1 Bq = one disintegration per second. Another commonly used but old unit is CURIE (Ci) 1 Ci = 3. 7 x 1010 Bq or 1 m. Ci = 37 MBq Radiation Protection Office
Half-Life Ao ½Ao A(t) = Ao exp (- lt) T½ = 0. 693 / l where l is the radioactive decay constant Radiation Protection Office
Typical Half-Lives Radionuclide H 3 C 14 P 32 S 35 Cs 137 Eu 152 I 131 Half-Life 12. 3 years 5760 years 14. 3 days 87. 2 days 30. 2 years 13. 5 years 8. 04 days Radiation Protection Office
Bremsstrahlung “Braking Radiation” X-rays produced when b particles are slowed down very rapidly as they come very close to an atomic nucleus. b shielding materials (e. g. Perspex) have relatively low atomic numbers in order to slow them down more gradually. Radiation Protection Office
Absorbed Dose (D) Energy imparted to matter in small volume Mass of the small volume 1 Gray (Gy) = 1 Joule of energy absorbed in 1 kg of matter i. e. 1 J / kg • Gy is a HUGE dose of radiation. (Old units : 1 gray = 100 rads) Radiation Protection Office
Equivalent Dose - H H = Absorbed Dose x Radiation Weighting (Grays) Factor (WR) Sieverts (Sv) which are still J / kg WR = 1 for photons and betas of any energy. (Old units : 1 Sv = 100 rem) Radiation Protection Office
Effective Dose (E) Accounts for uneven irradiation of the body. Represents overall risk from a whole body exposure. E = S T w. T x HT where HT = Equivalent dose to tissue / organ “T” w. T = Tissue weighting factors represent risks of detrimental radiation effects to different organs or tissue Radiation Protection Office
Tissue Weighting Factors Gonads Red bone marrow Colon Lung Stomach Bladder Brain 0. 08 0. 12 0. 04 0. 01 Remainder 0. 12 includes: Adrenals Small intestine Kidney Pancreas Thymus Breast Liver Oesophogus Thyroid Skin Bone surfaces Salivary glands 0. 12 0. 04 0. 01 Upper large intestine Muscle Spleen Uterus WT = å T 1
Internal Radiation Amount of radionuclide in body Dose rate in organ l. EFF = l. R + l. B exp(-l. Rt) exp(-l. Bt) exp(-l. EFFt) Time (post ingestion) Radiation Protection Office
Committed Equivalent Dose Equivalent dose summed HT(50) = over a 50 year period. Also Committed Effective Dose Radiation Protection Office
Annual Limit of Intake (ALI) The amount of radionuclide (in Bq) which when taken into the body will result in : Committed Effective Dose = Dose Limit (20 m. Sv) Radionuclide Sodium-22 Iodine-131 ALI (MBq) Inhalation Ingestion 10 7 1 0. 8 Also depends on chemical compound. Radiation Protection Office
Principles of Radiation Protection v Justification – Benefits > Risks v Optimisation - ALARP v Dose Limitation Radiation Protection Office
Practical Protection Measures External Radiation Distance : inverse square law. : always use remote handling (if poss). Shielding : placed between worker & source. : attenuates the radiation. : lead for g, perspex for energetic b. Time : be as quick as safely possible. Radiation Protection Office
To use tongs or not to use tongs? 30 cm 10 mins @ 1 m. Sv/min Þ 10 m. Sv 1 cm 1 min @ 900 m. Sv/min Þ 900 m. Sv Radiation Protection Office
Personal Monitoring v Normally TLD badges. v Worn as instructed in local rules. v Do not try to remove TLDs from holder. v Damaged holders replaced immediately. v NOT left in radiation areas, left on radiators, washed etc. v Returned for reading promptly. v Special monitors for wrists, eyes etc. NOT whole body one. Radiation Protection Office
Practical Protection Measures Internal Radiation Use all appropriate protective clothing e. g. lab coats, gloves, glasses. No mouth work. Only handle sources in designated areas. Know the whereabouts and how to use the decontamination kit. Radiation Protection Office
Do NOT eat drink or smoke in an area where unsealed radioactive substances are handled. “What the? …… This is lemonade! Where’s my preparation of tritiated thymidine? ” Radiation Protection Office
DO NOT WEAR LAB COATS IN THIS ROOM Radiation Protection Office
Legislation The Environmental Permitting Regulations 2016 (EPR 2016) + 2018 Amendment The Ionising Radiations Regulations 2017 (IRR 17) Radiation Protection Office
EPR 2016 Protection of General Public and Environment. PERMITS: to keep & use sealed radioactive SEALED : sources. Subject to national security OPEN : to keep and use unsealed radioactive substances and accumulate/dispose of waste Policed by The Environment Agency (EA) Radiation Protection Office
Record Keeping ü ü Date received, radionuclide, activity Location stored Details of removal for use, date, activity Activity present in stock at end of month v Dates of disposal v Total activity disposed of and by which route each month v Total activity of waste accumulated at end of each month Radiation Protection Office
Where does all the waste go ? SOLID : Very Low Level Waste (VLLW) Þ skip by user. Low Level Waste (LLW) from bins in labs collected and taken for incineration (or landfill burial) Sealed sources – specialist contractor LIQUID : Aqueous – down the drain Organic – collected and sent for incineration Radiation Protection Office
Waste Disposal IS VERY EXPENSIVE: When buying new sources – think about disposal costs and work this into the grant application Radiation Protection Office
Orphans Radioactive sources or materials or waste that does not have an ‘owner’ Creates a lot of work for RPO has to pay for its legal disposal PLEASE NO ORPHANS X Radiation Protection Office
When an Inspector Calls !! • • • Poor accounting of sources and waste Lost sources Unauthorised disposal of waste Over-accumulation of waste Failure to keep suitable and sufficient records Failure to use best practicable means (BPM) Radiation Protection Office
Offences Variety of offences & penalties Penalties can be applied to anyone within the University - not just the COO or Department Head Non-compliance with Permit conditions/schedules - up to £ 20, 000 fine and/or up to 6 months in prison Failure to keep records - a fine and/or up to 3 months imprisonment Radiation Protection Office
IRR 17 Protection of the Worker. Policed by The Health & Safety Executive (HSE). • • • Risk Assessments (8) Annual Dose Limits (12) Area Classification and Monitoring (17, 20) Local Rules (18) Accounting for, Keeping and Moving Radioactive Substances (29+30) Radiation Protection Office
Risk Assessment Must be made prior to commencing any new work involving ionising radiation. Identify hazards Who could be harmed Significant hazard but is it a risk? Evaluate risks Record findings Review / revise Radiation Protection Office
Annual Dose Limits (ICRP 103) Occupational Public (m. Sv) Effective Dose 20 1 Eye Lens Skin Extremities 20 500 15 50 - Stochastic Deterministic Radiation Protection Office
Area Classification and Monitoring Controlled : > 3/10 th of any dose limit. : significant risk of spreading contamination. Supervised : reviewed as to controlled status. : > 1/10 th of any dose limit. : effective dose > 1 m. Sv per year. Monitoring for Contamination must be done regularly (at least weekly µ nature of work). Radiation Protection Office
• • Local Rules Names of appointed persons Duties and responsibilities Classification of areas Systems of work - record keeping - ordering - experimental procedures • Personnel monitoring procedures • Dose investigation level – 2 m. Sv • Contingency plans – loss, theft, spillage Read, Understand Sign (RP 6 form) Radiation Protection Office
Accounting for, Keeping and Moving Radioactive Substances House-keeping and records for quantity & location Stored substances kept in suitable receptacle & store Suitable & labelled package whilst being moved Radiation Protection Office
Regulatory Control • Each source must have an ‘owner’ • Sources marked permanently with unique ID number, trefoil and key data – Due to the physical size often not possible • Label the container – can lead to loss when users put the wrong sources back in the wrong pot • Record Keeping – IRR 17 Regulation 29 and EPR 2016 Permit conditions – Inventory list of all sources – RPS should maintain a central record of all sources – Source usage record for each source – date logged out, to where and why, by whom, date logged back in to store – Monthly checks on locations with a record of the check – Records of disposals Radiation Protection Office
Records • • • Radionuclide (*) Source ID number (*) Activity (*) and supplier's reference date (*) Date received onto the premises If in equipment – what type, model, serial number Current location Current leak test certificate (*) Current source ‘owner’ Date and manner of disposal of the source Keep these for at least two years (IRR 17) but will also need these ones (*) at disposal time Radiation Protection Office
Leak Testing • Records of Leak Test – source (identification number) – date carried out – who did the test – method of test – instrument used (serial number) – numerical result – pass or fail – action if failed Radiation Protection Office
Disposal • Removal of sources from pieces of equipment – Care with LSC sources – very small and can be difficult to extract (without an angle-grinder!!) – Will need a suitable store for source once out – Remove all the labels from the equipment before scrapping ! • Disposal options – – – Perhaps Exempted or VLLW via decay Solid incineration – if in Permit conditions Supplier might take back Sale or gifting to bona-fide organisations Specialist disposal • ACB, Gamma Services, Babcock etc. Radiation Protection Office
Source Security • • Sources must be held securely Locked in a secure/shielded store when not in use ONE physical barrier OK for most materials BUT some higher activity sources need at least TWO physical barriers + alarms + PIR + CCTV etc. • High Activity Sealed Sources – HASS • Comply with guidelines from Na. CTSO • Inspections by Counter-Terrorism Officers Radiation Protection Office
Transport of Radioactive Materials (Carriage of Dangerous Goods Regulations) Consignor – prepares and/or sends Carrier – physically transports Consignee – receives If going to be Consignor or Carrier – must contact The Radiation Protection Office to discuss arrangements e. g. Type of package, vehicle placards Must not be in private car – insurance invalidated Even as Consignee – written procedure for receipt Radiation Protection Office
The Radiation Protection Office (RPO) Professor Pete Cole (Room 406 794 3467) Radiation Protection Adviser / Radioactive Waste Adviser Miss Louise Nicholson (Room 406 795 7305) Radiation Protection Adviser / Radioactive Waste Adviser Mr John Ryan (Room 407 794 3466) (Room 407 794 3465) Radiation Protection Technician Mr Paul Davies Radiation Protection Technician rad. pro@liv. ac. uk Radiation Protection Office
Work of the RPO (includes!!) J J J J Advice to University staff on complying with regs. Departmental audits to ensure safe practice. Liaison with EA, HSE, NRPB, SRP and AURPO. Disposal of radioactive waste. Monitoring staff doses. Dealing with incidents and issues. Communicating with the media. Radiation Protection Office
The RPO Website www. liv. ac. uk/radiation Details of RPO and how to contact us. Basic information on radiation hazards. Documents - Generic Local Rules. - Online Radiation Worker Registration - Waste Collection Request Forms. - Risk Assessment Forms. Radiation Protection Office
Basic Radiation Protection and Legislation Overview Radioactive Substances Thanks for Listening Whoops! Radiation Protection Office
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