B7 Flashcards
an 20 Jan 12 Jul 08 Jul 07 Jul 05
(a) Identify the possible health effects from exposure to ionising radiation. (5)
(b) Outline the control measures that should be in place where persons may be exposed to ionising radiation at work. (15)
(a) Health effects include: • Skin burns, reddening, blistering, ulceration • Nausea/vomiting • Diarrhoea • Hair loss • Headaches • Sterility • Eye cataracts • Cancer/tumours • Genetic damage causing birth defects
(b) Control measures include:
• Keeping inventory control of radiation sources
• Secure sealed Storage of sources
• Appointment of competent people such as radiation protection advisors and supervisors
• Applying the distance, time and shielding approach
− Increase the distance between the radiation source and those at risk - Doubling the distance from source reduces exposure to 1⁄4
− Reduce the length of time that people are exposed for
− Use of shields such as walls and lead lined aprons to absorb the radiation
• Exclusion of particularly vulnerable groups such as young persons and pregnant women
• Minimising the number of people exposed
• Prohibition of eating/drinking in the area where sources are used
• Good hygiene practices – hand washing after handling source
• Personal Dosimetry measurement of staff to ensure safe limits are observed
• Health Surveillance of staff to identify early signs of exposure
• Safe disposal of radioactive materials/waste
Jul 19
Lasers are often used by the entertainment industry during displays and music concerts attended by members of the public. The lasers used are of very high power and are given a hazard classification.
(a) Outline the hazard classification system used for lasers. (4)
(b) Outline how exposure to lasers can cause damage to the eyes. (6)
(c) Outline control measures that could be used to reduce the risks to the public at such displays. (10)
(a) British Standard EN 60825-1 classifies lasers from 1 to 4 (plus sub-categories) with 1 being the lowest power and therefore least hazardous and 4 being over 500mW. Class 1 is considered intrinsically safe whilst Class 4 representing high risk of permanent eye damage and risk of burns to skin.
(b) The laser beam can be focussed through the cornea and lens onto the retina where it is more concentrated and produces a heating effect. The severity of the damage depends on the wavelength, duration and angle of exposure. In more severe cases it can cause blindness.
(c) control measures include:
• Carry out risk assessment
• Eliminate as far as possible-by means of alternative technologies
• Use of a protective shielding for the lasers, controlled by interlock systems;
• Layout of the workplace to reduce exposure
• Use by only competent or trained operators
• Prevention of unauthorised access to hazardous areas.
• Limit duration and intensity of exposure whilst ensuring lasers are within the maximum
permissible exposures (MPE) set down in standards
• Making on-site measurements to confirm the MPE is complied with.
• Introduce Safe System of Work (SSW)
• Use of eye protectionUse of warning signs
• Provision of appropriate information and training
• Provision and use of specialist advice- person appointed with responsibility for radiation safety
Jan 19
Glass blowers use furnaces to produce molten glass that they then blow into shapes to make glasses and vases. During their work they are exposed to different types of non-ionising optical radiation.
(a) Identify the possible ill-health effects to the glass blowers from exposure to the non-ionising optical radiation. (3)
(b) Describe the specific requirements of the personal protective equipment that would be required to protect the glass blowers from the non-ionising optical radiation. (3)
(c) Other than ill-health effects and control measures, outline what should be considered in a radiation risk assessment. (4)
(a) Exposure would be to both infra-red a ultraviolet. Ill health effects include:
• skin reddening
• skin cancer
• cataracts
• Whole body heating or thermal discomfort
(b) PPE would include:
• Leather gauntlets or long heat resistant gloves that would protect against the infrared radiation.
• Goggles, glasses or a visor with a UV and IR filter to protect the eyes from both these types of
radiation.
• Long-sleeved clothing and leather apron would also afford protection from UV and IR radiation
respectively.
(c) The risk assessment should also consider:
• The assessment or measurement of the actual levels of exposure to the radiation
• Comparison of these to the exposure limits and exposure values
• Duration of exposure
• Proximity or closeness to the source
• Results of health surveillance in order to give an indication of any over-exposure that may be occurring
Jan 18 Jan 11 Jul 07
(a) Outline the properties of:
(i) alpha particles (4)
(ii) x- rays (4)
(b) Staff working in a dental practice are exposed to x-rays.
(i) Outline the legal requirements for monitoring staff exposure to x-rays. (6)
(ii) Outline how the dental practice can monitor the staff exposure. (6)
(a) (i) Alpha particles are particulate (= Helium nuclei He 2+ ions - having a relatively large mass and size); they are emitted during the radioactive decay of radio-nuclides and are highly ionising with the potential for seriously harmful health effects if ingested or inhaled or otherwise absorbed into the body; however alpha particles are only weakly penetrating - pass through the skin but not tissues / organs.
(ii) X-rays are a form of high energy electromagnetic radiation (“waves”),(non-particulate) which are generated artificially by the deceleration of electrons in a solid medium; as such they have no physical mass. X-rays are highly penetrating but less ionising than alpha particles.
(b) (i) The legal requirements for monitoring staff are set out in IRR 99; exposure not to exceed specified dose limits (IRR reg 11) - dose limitation requirements apply for YPs / N&EMs / parts of body ; duty to monitor exposure of dental nurses etc; need to use an approved dosimetry service; need to appoint an RPS to oversee monitoring programme / management of dose badges etc in accordance with local rules; keep records of monitoring / dose for 50 years or up to age 75; any person receiving / likely to receive a dose of > 6mSv / year or >3/10ths of any relevant dose limit must be monitored as a “classified worker” (to be notified in writing); carry out checks / maintenance on x-ray equipment
(ii) Exposure of dental practice staff (dentists / dental nurses and hygienists) to X-rays can be monitored by means of a radiation film badge (or thermo-luminescent badge - LiF / MgSO4); the badge is attached to the clothing of the exposed worker (lapel / hip); the film badge is film in a plastic holder; the TLD is in a metallic holder; the badge detects incident radiation and is sent away periodically to an approved dosimetry service where the radiation dose can be measured; the film badge “develops” (darkens) on exposure to radiation - thelevel of darkness indicating the level of exposure (dose); for TLD the badge is heated (thermo) and re-emits light (luminesces) - the amount of light emitted indicates the level of exposure.
Radiation monitoring is relevant to ensuring compliance in that the results can be used to ensure that the requirements of IRR 99 are being met - in particular that local rules for the control of radiation hazards in any supervised and controlled areas are being complied with and that the dose limits specified in regulation 11 IRR 1999 in relation to employees, YPs, women of child-bearing capacity, classified workers and specific organs / tissues are not being exceeded. Records of radiation exposures must be kept for at least 50 years (or until age 75).
Key principles of control include:
reducing duration of exposure - this reduces dose (effects are dose dependent)
increasing distance from source - inverse square law applies (x2 distance = 1/4 dose)
shielding - barriers, screens, PPE (eg lead aprons) can reduce exposure by blocking radiation
ICRP / NRPB / HPA principles include: justification (benefit must outweigh potential harm); dose limitation, dose optimisation = using minimum intensity and dose necessary
Jul 16
An employer is concerned about employee exposure to radon and related ill-health. The workplace is a building with a basement and a ground floor. Measurements show that levels of radon in the basement
are in excess of 400 Bq/m3.
(a) Explain how radon could be present in the basement. (3)
(b) Explain the mechanism by which radon could cause harm to the lungs. (3)
(c) Comment on the significance of the radon level measured in this workplace. (1)
(d) Outline measures that could be put in place to help reduce employee exposure to radon. (3)
(a) Radon is a gas that naturally occurs in some rocks as a decay product of uranium. Since it is heavier than air it can accumulate in basements
(b) Radon particles attach themselves to dust particles and water droplets which means they are not readily exhaled. Also, there is significant risks of the further decay of radon once it is inside the body, as it continues to emit alpha particles. This is in contrast to the risks posed by alpha particles outside the body as they can easily be stopped by skin.
(c) This level of exposure falls within the scope of the Ionising Radiations Regulations 1999 and are therefore subject to the required arrangements for the management of radiation protection.
(d) Measures that could be put in place include:
• Installing a ‘radon proof membrane’ within the floor structure to stop movement to ground floor
• Improving ventilation
• Sealing gaps between floor and subfloor
• Use of a “Radon sump” with extraction pipework to remove Radon from area
Jan 14
Construction workers often spend much of their time working outdoors where they are exposed to naturally occurring ultra-violet (UV) radiation.
(a) (i) Identify the acute adverse effects that could result from exposure to UV radiation. (2)
(ii) Identify the chronic effects that could result from exposure to UV radiation. (2)
(b) Explain measures that the workers can take to reduce the risks associated with UV exposure. (6)
(a) (i) heat rash, itchy, reddened, dry peeling skin, blisters (ii) skin cancer – squamous cell / basal cell / melanoma; premature aging
(b) Carry out work in shaded areas; PPE: loose-fitting clothing, hardhat + neck protection, sunglassess (high factor), sunscreen SPF>15, self- checking / skin inspection – early signs of skin changes, active moles, spots, discolouration
An employer is concerned that the building where a number of employees work may have high levels of the ionising radiation radon.
(a) Identify the possible effects this may have on the employees’ health. (2)
(b) Identify the route by which employees can be exposed to radon. (2)
The level of radon in the ground floor and basement store rooms exceeds 400Bq/m3.
(c) Outline the steps that the employer must take to reduce the employees’ exposure to radon. (4)
(a) radon is an alpha emitter - alpha particles are highly ionising over a short distance; once inside the body the high intensity ionisation causes localised cell abnormalities - damage to DNA / uncontrolled cell replication / tumour formation commonly resulting in lung (and other) cancer. [“causes cancer” not insufficient]
(b) employees can be exposed both externally and internally - where the radon occurs naturally in rock as a decay product of uranium and continues through to when the decay products of radon can become lodged in the lungs. [“by inhalation” not sufficient].
(c) Reference to the general principles of time, distance and shielding alone is not sufficient; need to fully address the range of control measures that are typically applied to buildings in geographic areas with high radon levels. Significance of 400Bq/m3 in relation IRR.
ul 12 Jan 11 Jan 09 Jan 06
Display lasers are used in a night club. Outline control measures to minimise the risk to club goers and staff. (10)
Design features:
• should be limited to lowest Class possible (likely to be Class 3 or 4 in this context)
• meets approved design standard / British Standard / CE
• laser should be “embedded” (not readily accessible)
• shielding / protective housing
• restricted angle
• beam enclosure, masking and stops
• avoid reflective surfaces / mirrors etc
• key control access with interlock to power supply
• warning signs displayed on equipment
• exposure not to exceed not to exceed MPE limit (even under fault conditions)
Procedural controls:
• assess the risks to employees and the public (especially audiences)
• only used approved installers
• staff training (+details)
• SSW / PTW for maintenance / repair
• manufacturer’s guidance followed
• appointment of competent person to oversee laser safety
• controlled access for maintenance / repair - via key system
• protective eyewear for people who may be exposed eg during alignment and setting up
• suitable defect reporting procedure in place
Comment: See HSG 95
Jan 10
(a) Outline the nature and properties of alpha particles. (4)
(b) Outline the principles that could be used to control exposure to alpha particles. (6)
(a) Alpha particles are a type of ionising radiation generated by radioactive decay of the nucleus of a radio-nuclide. Alpha particle consists of 2 protons + 2 neutrons and carries a 2+ charge (=Helium nucleus); highly ionising therefore very dangerous if absorbed via inhalation, ingestion etc; weak penetrating power - stopped by a few cm of air, skin, water etc so little danger outside the body.
(b) Control exposure by:
• shielding / containment - alpha sources should be contained in a sealed unit glove boxes etc
• reducing duration of exposure - job rotation - ensure dose limits not exceeded
• increase distance - as above low penetrating power
• decontaminate surfaces / areas etc
• no eating, drinking, smoking, application of cosmetics etc in restricted area cover cuts, wounds
Jul 09
A new leisure centre is planning to install ultra-violet (UV) tanning equipment. The equipment uses UV sources with a higher intensity than normal sunlight to accelerate tanning.
(a) Outline control measures that should be put in place for BOTH employees and customers for the safe operation of this facility. (12)
(b) Identify BOTH the acute and chronic effects that could result from exposure to UV radiation. (4) (c) Outline TWO other examples of occupational exposure to UV radiation. (4)
(a) See Jan 07(a) & (b)
(b) Potential health effects from the use of UV tanning equipment include:
Acute: skin burns (erythema) (heat rash); photo-keratitis (“arc-eye”)
Chronic: skin cancer (melanoma); eye damage (cataracts); premature ageing of skin
(c) Outdoor working - road repair; beach lifeguard; agricultural workers; welders; dentists / dental assistants; printers - users of lasers.
Comment: UVR is not ionising – so no lead shielding and no IRR 99! No marks for covering skin with sun block cream and/or clothing, or closing the facility because it is `too risky’.
Jan 09 Jan 06
(a) Identify the way in which lasers are classified according to their hazard. (6)
(b) Low power lasers are widely used to read bar-code labelled products at checkouts in retail
premises. Outline the design features that should be incorporated into these laser products to ensure their safe operation and maintenance. (4)
a) EN 60825-1 sets out the criteria for the classification of lasers as follows:
Laser class. Hazard
Class 1
Least hazardous = “eye safe”
Class 1M
Safe for viewing directly with the naked eye, but may be hazardous to view with the aid of optical instruments
Class 2
Visible lasers - safe for accidental viewing under all operating conditions but may not be safe for a person who deliberately stares into the laser beam for longer than 0.25 s by overcoming natural “blink response”
Class 2M
Same as for Class 2 above, but may be hazardous (even for accidental viewing) when viewed with the aid of optical instruments, as with class 1M.
Class 3R
Considered low risk, but potentially hazardous. The class limit for 3R is 5x the accessible emission limit (AEL) for Class 1 (for invisible radiation) or class 2 (for visible radiation). Hence visible lasers emitting between 1 and 5 mW are normally Class 3R.
Class 3M
Very likely to be dangerous. For a continuous wave laser the maximum output into the eye must not exceed 500mW. The radiation can be a hazard to the eye or skin. However, viewing of the diffuse reflection is safe.
Class 4
Very dangerous and viewing of the diffuse reflection may be dangerous. Class 4 laser beams are capable of setting fire to materials onto which they are projected.
Laser Class is determined by reference to their accessible emissions – maximum permissible exposure in mW (continuous wave lasers) or J m-2 (if pulsed)
(b) Design features:
• should be limited to lowest Class possible (Class 1 or 2 in this context)
• shielding / protective housing
• trigger operation for hand-held versions
• laser should be “embedded” (not readily accessible)
• avoid reflective surfaces / mirrors etc
• key control access with interlock to power supply
• warning signs displayed on equipment
Jan 07
A new sports and leisure centre that provides facilities for the general public is planning to install a range of UV tanning equipment. The equipment uses UV sources with a higher intensity than normal sunlight to accelerate tanning.
(a) Describe what should be included in the training given to employees who will operate this facility to ensure both their safety and that of the customers. (6)
(b) Suggest other control measures that should be put in place for the safe operation of this facility.(4)
(a) Training for operators should cover: the nature of uv radiation; health hazards; vulnerable skin types; providing advice on control measures for users - time restrictions / PPE (uv goggles), sun block creams etc; how tanning machinery operates - pre-user check procedures; safety controls - shut off devices / alarms etc; potential failure modes; importance of cleaning between users; emergency procedures - raising alarm / first-aid.
(b) Other control measures include: user-induction session to include assessment of skin type, family history, medication, pregnancy etc; safety features of equipment (as above); application of age restrictions - U18; siting staff workstations away from tanning equipment; separation of tanning equipment from staff areas - barriers / screens; ensuring plentiful supply of goggles; supervision of users - use of PPE / compliance with time restrictions etc.; automatic timer / shut off; warning signs & information posters displayed; keeping records of use / exposure.
Jan 06
Low Power lasers are widely used to read bar-code labelled products at checkouts in retail premises. There is no specific regulatory legislation relating to the use of these laser products.
(i) Identify statutory legislation that should be considered by retailers in relation to the use of these laser products. (2)
(ii) Outline the design features and the procedural controls that should be in place to ensure safe operation and maintenance of this equipment. (8)
(i) No specific “laser regs” [Note: IRR 99 does not apply - lasers are NON-IONISING] HSWA s2 - safe plant and equipment etc
HSWA s3 - customers
MHSWR reg 3 - risk assessment
PUWER reg 5 - maintenance etc
EAWR - electrical safety
EN 60825-1 sets out requirements for the classification of lasers - but this is not legislation
(ii) Design features:
• should be limited to lowest Class possible (likely to be Class 3 or 4 in this context)
• meets approved design standard / British Standard / CE
• laser should be “embedded” (not readily accessible)
• shielding / protective housing
• restricted angle
• beam enclosure, masking and stops
• avoid reflective surfaces / mirrors etc
• key control access with interlock to power supply
• warning signs displayed on equipment
• exposure not to exceed not to exceed MPE limit (even under fault conditions)
Procedural controls:
• assess the risks to employees and the public
• only used approved installers
• staff training (+details)
• SSW / PTW for maintenance / repair
• manufacturer’s guidance followed
• appointment of competent person to oversee laser safety
• controlled access for maintenance / repair - via key system
• protective eyewear for people who may be exposed eg during alignment and setting up
• suitable defect reporting procedure in place
Comment: See HSG 95
Jul 05
A research company is proposing to use small amounts of unsealed radioactive chemicals to act as tracers in the monitoring of the uptake and progress of chemical substances in micro-organisms. Outline the key risk control measures that should be considered, and describe the specific legal requirements that would apply, with respect to the risk from radiation. (20)
In these circumstances all risk control measures should follow a hierarchy of control in order to meet the requirements of the Ionising Radiations Regulations 1999. The risk control measures that should be considered
include:
• elimination of the risk - since under IRR 1999 the use of radioactive material must be justifiable.
Consequently, if the use cannot be justified (ie if there is another equally effective and suitable alternative technique) then radioactive material should not be used. The risk could possibly be eliminated by use of alternative methods of monitoring uptake eg non-radioactive chemical tracers or possibly by contracting the work out.
• substitution - use less hazardous radioactive material with lower radiation risks and a shorter half-life
• carrying out the work in a segregated and secure area
• ensuring containment (by carrying out the activity in a glove box or fume cupboard)
• the use of PPE (eg. gloves, aprons, face shields)
• providing appropriate information, instruction and training
• maintenance and testing of control measures eg measurement of the effectiveness of containment
equipment
• the cleaning/ disposal of PPE
• providing good hygiene facilities, changing areas etc.
• restricting access to the area
• using low volatility chemicals
• using hand-held monitors
• having emergency arrangements in place to contain and deal with any spillages of the radioactive
chemicals
• having a procedure for waste disposal
IRR 99 requires radiation employers to:
• appoint a radiation protection adviser (RPA) and radiation protection supervisors (RPSs)
• notify the enforcing authorities (HSE) of the work activities
• conduct a risk assessment
• apply a hierarchy of control as described above
• apply “local rules”
• designate “controlled areas ” and “supervised areas” (signage)
• conduct personal dose monitoring using a validated monitoring service
• ensure dose limits (reg 11 IRR 99) in relation to employees, YPs, women of child-bearing capacity,
classified workers and specific organs / tissues are not being exceeded
• keep dosimetry records for at least 50 years (or until age 75)
• designate and appoint “classified persons”
• provide health / medical surveillance
• monitor work areas
• calibrate monitoring equipment
• display radiation hazard warning signs
Comment: The question identified two issues - control measures and legal requirements - both need to be dealt with in detail. If you don’t know anything about IRR 99 or radiation protection measures choose a different question!
Jul 05
A research company is proposing to use small amounts of unsealed radioactive chemicals to act as tracers in the monitoring of the uptake and progress of chemical substances in micro-organisms. Outline the key risk control measures that should be considered, and describe the specific legal requirements that would apply, with respect to the risk from radiation. (20)
In these circumstances all risk control measures should follow a hierarchy of control in order to meet the requirements of the Ionising Radiations Regulations 1999. The risk control measures that should be considered
include:
• elimination of the risk - since under IRR 1999 the use of radioactive material must be justifiable.
Consequently, if the use cannot be justified (ie if there is another equally effective and suitable alternative technique) then radioactive material should not be used. The risk could possibly be eliminated by use of alternative methods of monitoring uptake eg non-radioactive chemical tracers or possibly by contracting the work out.
• substitution - use less hazardous radioactive material with lower radiation risks and a shorter half-life
• carrying out the work in a segregated and secure area
• ensuring containment (by carrying out the activity in a glove box or fume cupboard)
• the use of PPE (eg. gloves, aprons, face shields)
• providing appropriate information, instruction and training
• maintenance and testing of control measures eg measurement of the effectiveness of containment
equipment
• the cleaning/ disposal of PPE
• providing good hygiene facilities, changing areas etc.
• restricting access to the area
• using low volatility chemicals
• using hand-held monitors
• having emergency arrangements in place to contain and deal with any spillages of the radioactive
chemicals
• having a procedure for waste disposal
IRR 99 requires radiation employers to:
• appoint a radiation protection adviser (RPA) and radiation protection supervisors (RPSs)
• notify the enforcing authorities (HSE) of the work activities
• conduct a risk assessment
• apply a hierarchy of control as described above
• apply “local rules”
• designate “controlled areas ” and “supervised areas” (signage)
• conduct personal dose monitoring using a validated monitoring service
• ensure dose limits (reg 11 IRR 99) in relation to employees, YPs, women of child-bearing capacity,
classified workers and specific organs / tissues are not being exceeded
• keep dosimetry records for at least 50 years (or until age 75)
• designate and appoint “classified persons”
• provide health / medical surveillance
• monitor work areas
• calibrate monitoring equipment
• display radiation hazard warning signs
Comment: The question identified two issues - control measures and legal requirements - both need to be dealt with in detail. If you don’t know anything about IRR 99 or radiation protection measures choose a different question!
