Orphan Source Search Training Basic Radiation Protection for

Orphan Source Search Training Basic Radiation Protection for Search Teams

Overview • Ionizing Radiation • Basic radiation protection – Biological effects – Significant doses • • • External radiological hazard and its control Internal radiological hazard and its control Basic radiological surveys Establishment of controlled areas Personal protection Basic Radiation Protection for Search Teams 2

Ionizing radiation and radioactive substances are all around us everyday Cosmic Rays Food & drink Radon Terrestrial gamma rays Basic Radiation Protection for Search Teams 3

Exposure to ionizing radiation cause injury in the short term and cancer in the long term Early or deterministic effects Late or stochastic effects • • • thyroid and other cancers • Higher radiation dose = higher risk of getting cancer • Although ionizing radiation cause mutations, no birth defects have been found among groups with the highest exposures – the Hiroshima. Nagasaki survivors Radiation burns Depressed blood count Hair loss Radiation sickness These ‘deterministic’ effects occur only above a certain (high) radiation dose Higher dose = worse effect Basic Radiation Protection for Search Teams 4

Ionizing radiation dose is measured in Sieverts 1 millisievert (m. Sv) = 1/1000 Sievert Basic Radiation Protection for Search Teams 5

Long Term Biological Effects of Ionizing Radiation • Increased cancer risk of about 5% per Sv (10 or more years after exposure) • Risk at lower doses is uncertain but probably lower Basic Radiation Protection for Search Teams 6

Penetration of Ionizing Radiation Basic Radiation Protection for Search Teams 7

Two types of Radiation Exposure: External and Internal Exposure from a radiation source outside the body (external hazard) Exposure due to inhaling or ingesting radioactive material (internal hazard) Basic Radiation Protection for Search Teams 8

How to control external exposure Basic Radiation Protection for Search Teams 9

External exposure: The ALARA Principle • While performing search activities keep radiation exposure As Low As Reasonably Achievable (ALARA) – Minimize time in the area – Maximize distance from the source – Use shielding if possible Basic Radiation Protection for Search Teams 10

Minimize Time • You will have to spend time in the area searching for the source – Move efficiently, but not faster than your meter can respond – Do not loiter in areas of elevated dose rates – Reduce the time in the area by one half and receive half the radiation exposure Basic Radiation Protection for Search Teams 11

Increase Distance • Even with sensitive search instruments you will have to be briefly in close proximity to sources to take radiation measurements. • When you don’t have to be close, move away • Double your distance from the source to reduce your exposure by a factor of four • Use long handled tools • Use an extended probe Basic Radiation Protection for Search Teams 12

Increase Distance 0. 25 m. Sv/hr @ 2 m 1 m. Sv/hr @ 1 m Basic Radiation Protection for Search Teams 13

Never pick up the source! (Use tools) Basic Radiation Protection for Search Teams 14

Use Shielding • Radiation exposures can be reduced by placing shielding around high activity sources • Denser materials make better shields • Improvise with materials available (steel, concrete) • Stand behind buildings, vehicles, rocks • NOTE that if an orphan source is shielded by surrounding materials like soil, sand, rock or concrete, it will be harder to detect Basic Radiation Protection for Search Teams 15

Internal exposures • You cannot apply time, distance and shielding once the radioactive material is inside the body • Inside the body, small quantities of radioactive material become more significant because they are incorporated into organs and tissues which they irradiate. • The radiation dose given to these organs and tissues is only gradually reduced by radioactive decay and by the body’s natural processes of elimination • Hence preventing loose radioactive material from getting inside the body is the most important means of control of internal exposures from contamination Basic Radiation Protection for Search Teams 16

How to control internal exposures • Therefore containment is the key: – Control access to potential sources of contamination – Wear proper protective clothing and equipment (PPE) Basic Radiation Protection for Search Teams 17

How to protect against internal exposure • Perform frequent surveys • No eating, drinking, smoking in potentially contaminated areas • Keep hands away from mouth • Cover any small cuts Basic Radiation Protection for Search Teams 18

Use appropriate protective clothing (PPE) • Appropriate clothing depends on the quantity and type of actual or suspected contamination – Shoe covers, lab coat, gloves – Boots, coveralls, gloves, masks – Disposable paper suit such as “Tyvec” and a respirator - for emergencies (this is outside the scope of routine orphan source search (OSS) training) Basic Radiation Protection for Search Teams 19

PPE and internal exposure • • • It is possible, but rare, that an orphan source might leak causing radioactive contamination and an internal radiation hazard. Therefore for the majority of orphan source searches, no respiratory protection is necessary Respirators are hard to properly fit and exhausting to work with in the heat Boots, gloves, coveralls and a hard hat are normally all that is needed If you encounter radioactive contamination, leave the area without spreading it and reconsider your search plan For most orphan source searches, trips and falls, jagged metal, holes in the ground and heat are the most common serious hazards Basic Radiation Protection for Search Teams 20

Dosimetry • Search team members need to wear: – Whole body dosimeters for recording dose of record – Alarming secondary dosimeters that provide real time indication of dose – Extremity dosimeters • Maintain records of the doses according to the search plan Basic Radiation Protection for Search Teams 21

Radiological surveys characterize the radiological environment around the source • Measure radiation dose rates • Always check gamma, then for other types of radiations if suspected (alpha, beta, neutron) • Assess contamination levels (surface or airborne) – Alpha, beta, gamma • NOTE that alpha is highly unlikely and not measurable except with very sensitive instruments on a hard surface Basic Radiation Protection for Search Teams 22

Gamma radiation surveys • Turn on and check the instrument: – Calibrated within the past 12 months? – Battery check OK? (Spare batteries available? ) – If not calibrated, do a response check with a known source and record of the value. Does it match previous values? • Ensure that the dose rate before starting to search is background or at an acceptable low level • Move towards the suspected radiation with the instrument on • ALWAYS TRUST YOUR INSTRUMENT! Basic Radiation Protection for Search Teams 23

Radioactive contamination surveys • Direct vs. Indirect • Direct: only in low background area • Direct: with instrument, measure count rate near the ground or surface of interest • Always protect the probe (put a glove on it) • Indirect: take swipe or small sample of surface material (dirt) and count it in a low background area • Use an indirect contamination check if the background is higher Basic Radiation Protection for Search Teams 24

If you find contamination, set up a controlled area • • Use hazard tape to mark the contaminated area. Try to assess the extent of the contaminated area Secure and control access to the area. Only persons with appropriate training should deal directly with a leaking source or with the contaminated area. • Seek help from the IAEA for leaking sources or for advice about how to deal with extensive contamination Basic Radiation Protection for Search Teams 25

Summary for Individuals • Wear proper dosimetry – Whole body dosimeter – Alarming secondary dosimeter – Extremity dosimeter • Use proper protective clothing and equipment (as needed) – Gloves – Coveralls – Boots (or easily decontaminated footwear) Basic Radiation Protection for Search Teams 26

Summary for Individuals • Carry appropriate radiation/contamination detectors – or be with someone who does • Observe appropriate controls in and out of the area • Know the radiation doses and dose rates (established in the physical search plan) that require action • Protect yourself from the environment (have water, sun cream, etc. ) Basic Radiation Protection for Search Teams 27

Video: Radiation and Health (6 min, 48 sec) (Canadian Nuclear Safety Commission) • http: //www. nuclearsafety. gc. ca/eng/resources/videos/player/i ndex. cfm? videoid=radiation_health Basic Radiation Protection for Search Teams 28

Thank you for your attention!