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Basic Radiation Protection PowerPoint Presentation

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This medical PowerPoint presentation is about radiation protection, the measures taken to protect people and the environment from the harmful effects of ionizing radiation.

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Slide 1-

Basic Radiation Protection
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Radioactivity Nuclide – a particular atomic nucleus with a specific number of protons (p) and neutrons (n). For example 31P 32P 33P Approximately 1700 known nuclides. About 1400 are unstable – RADIONUCLIDES. Radionuclides - imbalanced numbers of p and n. - emit particles/energy to improve stability
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Radioactivity Charged particle Radionuclide Excited daughter Stable daughter Gamma photon Excess energy Disintegration
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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
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Main Emissions Alpha (a) Helium nuclei (2p + 2n) + 2 positive charge 4 mass units Beta (b) Gamma (g) High speed electrons 1 negative charge 0.0005 mass unit Electromagnetic photons No charge No mass
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Energy Energy of emissions Þ ELECTRONVOLTS (eV) 1 eV = energy gained by an electron passing through an electrical potential of 1 volt 1 eV is a very small energy = 1.6 x 10-19 joules. Normally emission energies are in keV or MeV range.
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Ranges V.Large V. Large 0.1 – 0.6 Gamma 600cm 8mm 1.70 P32 2cm 0.3mm 0.156 C14 4mm 0.05mm 0.018 H3 Beta few cm < 1mm 3 - 7 Alpha Air Tissue Range Energy (MeV) Particle
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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 mCi = 37 MBq
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Half-Life Ao ½Ao T½ = 0.693 / l A(t) = Ao exp (- lt) where l is the radioactive decay constant
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Typical Half-Lives 8.04 days I131 13.5 years Eu152 30.2 years Cs137 87.2 days S35 14.3 days P32 5760 years C14 12.3 years H3 Half-Life Radionuclide
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Bremsstrahlung “Braking Radiation” X-rays produced when b particles are slowed down very rapidly as they come very close to an atomic nucleus. shielding materials (e.g. Perspex) have relatively low atomic numbers in order to slow them down more gradually.
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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)
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Equivalent Dose - 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) H =
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Effective Dose (E) Accounts for uneven irradiation of the body. Represents overall risk from a whole body exposure. E = wT x HT where HT = Equivalent dose to tissue / organ “T” wT = Tissue weighting factor Tissue weighting factors represent risks of detrimental radiation effects to different organs or tissue T S
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Tissue Weighting Factors Gonads 0.08 Breast 0.12 Red bone marrow 0.12 Liver 0.04 Colon 0.12 Oesophogus 0.04 Lung 0.12 Thyroid 0.04 Stomach 0.12 Skin 0.01 Bladder 0.04 Bone surfaces 0.01 Brain 0.01 Salivary glands 0.01 Remainder 0.12 includes: Adrenals Upper large intestine Small intestine Muscle Kidney Spleen Pancreas Uterus Thymus å WT = 1
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Internal Radiation Time Time (post ingestion) Amount of radionuclide in body Dose rate in organ exp(-lRt) exp(-lBt) exp(-lEFFt) lEFF = lR + lB exp(-lEFFt)
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Committed Equivalent Dose HT(50) = Equivalent dose summed over a 50 year period. Also Committed Effective Dose
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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 (20mSv) Radionuclide ALI (MBq) Inhalation Ingestion Sodium-22 10 7 Iodine-131 1 0.8 Also depends on chemical compound.
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Principles of Radiation Protection Justification – Benefits > Risks Optimisation - ALARP Dose Limitation
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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.
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To use tongs or not to use tongs? 30cm 1cm 10mins @ 1mSv/min Þ 10 mSv 1min @ 900mSv/min Þ 900 mSv
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Personal Monitoring Normally TLD badges. Worn as instructed in local rules. Do not try to remove TLDs from holder. Damaged holders replaced immediately. NOT left in radiation areas, left on radiators, washed etc. Returned for reading promptly. Special monitors for wrists, eyes etc. NOT whole body one.
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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.
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“What the? …… This is lemonade! Where’s my preparation of tritiated thymidine?” Do NOT eat drink or smoke in an area where unsealed radioactive substances are handled.
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DO NOT WEAR LAB COATS IN THIS ROOM
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Legislation The Environmental Permitting Regulations 2016 (EPR2016) + 2018 Amendment The Ionising Radiations Regulations 2017 (IRR17)
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EPR2016 Protection of General Public and Environment. SEALED : to keep & use sealed radioactive sources. Subject to national security OPEN : to keep and use unsealed radioactive substances and accumulate/dispose of waste Policed by The Environment Agency (EA) PERMITS:
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Record Keeping Date received, radionuclide, activity Location stored Details of removal for use, date, activity Activity present in stock at end of month Dates of disposal Total activity disposed of and by which route each month Total activity of waste accumulated at end of each month
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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
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Waste Disposal IS VERY EXPENSIVE: When buying new sources – think about disposal costs and work this into the grant application
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Orphans Radioactive sources or materials or waste that does not have an ‘owner’ Creates a lot of work for RPO RPO has to pay for its legal disposal PLEASE NO ORPHANS X
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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)
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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
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IRR17 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)
Slide 36-

Risk Assessment Must be made prior to commencing any new work involving ionising radiation. Identify hazards Who could be harmed Evaluate risks Record findings Review / revise Significant hazard but is it a risk?
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Annual Dose Limits (ICRP103) 15 50 - 20 500 500 Eye Lens Skin Extremities 1 20 Effective Dose Public (mSv) Occupational (mSv) Stochastic Deterministic
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Area Classification and Monitoring Controlled : > 3/10th of any dose limit. : significant risk of spreading contamination. Supervised : reviewed as to controlled status. : > 1/10th of any dose limit. : effective dose > 1mSv per year. Monitoring for Contamination must be done regularly (at least weekly µ nature of work).
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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 – 2mSv Contingency plans – loss, theft, spillage Read, Understand and Sign (RP6 form)
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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
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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 IRR17 Regulation 29 and EPR2016 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
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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 (IRR17) but will also need these ones (*) at disposal time
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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
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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.
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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 NaCTSO Inspections by Counter-Terrorism Officers Source Security
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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
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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) Radiation Protection Technician Mr Paul Davies (Room 407 794 3465) Radiation Protection Technician rad.pro@liv.ac.uk
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Work of the RPO (includes!!) 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.
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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.
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Whoops! Radioactive Substances Basic Radiation Protection and Legislation Overview Thanks for Listening