IAEA Workshop about Radioactivity in Scrap Metal Module

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IAEA Workshop about Radioactivity in Scrap Metal Module 06 – MONITORING AND DETECTION IAEA

IAEA Workshop about Radioactivity in Scrap Metal Module 06 – MONITORING AND DETECTION IAEA International Atomic Energy Agency

This presentation describes radiation monitoring and detection techniques that may be useful when handling

This presentation describes radiation monitoring and detection techniques that may be useful when handling scrap metal IAEA 2

Places to perform radiation monitoring • Point of origin • scrap metal producers and

Places to perform radiation monitoring • Point of origin • scrap metal producers and • demolition sites) But these are (sadly) rare • Border crossings (land & sea) • Metal scrap yards, processing facilities and melting plants • Near the end of the supply chain IAEA 3

Agenda for Monitoring • Administrative monitoring • Visual monitoring • Radiation Monitoring: • •

Agenda for Monitoring • Administrative monitoring • Visual monitoring • Radiation Monitoring: • • Does it contain radioactivity? (But not always) Where in the consignment? What is the nature of the radioactivity? How much is there present ? (not so easy)! IAEA 4

Administrative monitoring • Scrap metal facilities should know • the place of origin of

Administrative monitoring • Scrap metal facilities should know • the place of origin of the scrap metal, • the scrap metal supplier • the history of previous supplier transactions • Review incoming shipments in relation to these factors. IAEA 5

Administrative monitoring • Beware of shipments that • arrive without evidence of radiation monitoring

Administrative monitoring • Beware of shipments that • arrive without evidence of radiation monitoring having been performed; • are from a supplier with a previous history of supplying radioactive scrap metal; and • are from a supplier not previously known to the recipient company or the regulatory authorities. IAEA 6

Visual monitoring • Persons handling scrap should be trained to recognize: • radioactivity warning

Visual monitoring • Persons handling scrap should be trained to recognize: • radioactivity warning signs. • the different types of radiation sources • the shapes of source housings • Guidance on the different types of radiation sources and source housings is contained in the IAEA’s International Catalogue of Sealed Radioactive Sources and Devices • (http: //www-pub. iaea. org/MTCD/publications/PDF/Pub 1278_web. pdf) IAEA 7

To help to identify sources and devices. . IAEA NOTE: You must be registered

To help to identify sources and devices. . IAEA NOTE: You must be registered to gain access! 8

Visual monitoring - what to look for. . IAEA 9

Visual monitoring - what to look for. . IAEA 9

Radiation Monitoring: Does it contain radioactivity? Where in the consignment? What is the nature

Radiation Monitoring: Does it contain radioactivity? Where in the consignment? What is the nature of the radioactivity? How much is there present ? IAEA 10

Radiation Monitoring: Does it contain radioactivity? Can often say, but not always Where in

Radiation Monitoring: Does it contain radioactivity? Can often say, but not always Where in the consignment? Can often localise What is the nature of the radioactivity? Often identify radioisotope How much is there present ? Not so easy! IAEA 11

Radiation Monitoring: Does it contain radioactivity? If it emits gamma radiation, it is likely

Radiation Monitoring: Does it contain radioactivity? If it emits gamma radiation, it is likely to be detectable • But the material it is within can shield out the radiation – reduce the “counts”, so • If time allowed to count is too short, it may not be detected by the electronics • If it emits alpha radiation – it will be undetectable in bulk – only detectable under laboratory conditions IAEA 12

Radiation Monitoring: Does it contain radioactivity? • It is really important to appreciate that

Radiation Monitoring: Does it contain radioactivity? • It is really important to appreciate that no radiation detection system is 100 per cent reliable • Some types of radiation are hard to detect and may get through the detectors Portal monitors are commonly used for checking vehicles (road and rail; sometimes, vehicles unloading ships alongside a quay) IAEA 13

Radiation source centered in load IAEA 14

Radiation source centered in load IAEA 14

Radiation source - vehicle geometry is important • Detectors may show different count rates

Radiation source - vehicle geometry is important • Detectors may show different count rates • Scrap metal in the load may shield the source • The vehicle steel will also shield the source • The presence of the metal vehicle and its load between the detectors will lower the background radiation count rate IAEA 15

Portal monitors – for bulk measurements A portal radiation monitor for train cars IAEA

Portal monitors – for bulk measurements A portal radiation monitor for train cars IAEA 16

An infrared sensor detects the vehicle IAEA 17

An infrared sensor detects the vehicle IAEA 17

Detector placement, configuration and vehicle speed are critical • Depends on the detector manufacturer

Detector placement, configuration and vehicle speed are critical • Depends on the detector manufacturer recommendations • Depends on standards Possible detector configurations: IAEA 18

Vehicle speed for effective monitoring • Note that the recommended vehicle speed varies from

Vehicle speed for effective monitoring • Note that the recommended vehicle speed varies from 5 km/hr to about 9 km/hr depending upon the standard that applies, the purpose of the monitoring (border or scrap facility) and the specifications and sensitivity of the detectors. • TOO FAST and low level or well-shielded sources may be missed • TOO SLOW and traffic is held up at busy locations IAEA 19

Portal radiation monitors need to be well shielded IAEA 3 cm of steel all

Portal radiation monitors need to be well shielded IAEA 3 cm of steel all around 20

Portal monitor characteristics • Usually large volume plastic scintillation detectors • Should be highly

Portal monitor characteristics • Usually large volume plastic scintillation detectors • Should be highly sensitive to detect small increases in • • • gamma radiation levels Are not sensitive at large distances (maximum distance of 6 metres between opposite portals) Not able to detect at large speed (> 10 km/hr) Usually an infrared sensor detects a vehicle and then starts a measurement Should have an audible and/or visual alarm Should be robust e. g. an anti-crash bar Should have a stop sign or barrier to control traffic IAEA 21

Crane (grapple) monitors IAEA 22

Crane (grapple) monitors IAEA 22

Crane monitor characteristics • Detector should be very robust and/or mounted so that the

Crane monitor characteristics • Detector should be very robust and/or mounted so that the detector can not be crushed • Should be mounted on top of a Grapple (distance) • Should be highly sensitive to detect small increases in gamma radiation levels • Should have an audible and/or visual alarm to alert the operator to a problem so that others may respond IAEA 23

Scrap handling IAEA 24

Scrap handling IAEA 24

Hand-held instruments: a radiation dose rate meter An instrument that is handheld can be

Hand-held instruments: a radiation dose rate meter An instrument that is handheld can be used to try to localise where the signal is coming from. It measures in microsieverts per hour If there is no focal point, it may indicate NORM IAEA 25

Hand-held instruments: A typical radiation contamination meter Measures in counts per second (cps) or

Hand-held instruments: A typical radiation contamination meter Measures in counts per second (cps) or may be able to approximate this to becquerels per cm 2 IAEA 26

Hand-held radiation dose rate meters IAEA 27

Hand-held radiation dose rate meters IAEA 27

Hand-held contamination meters IAEA 28

Hand-held contamination meters IAEA 28

Hand-held gamma spectrometers • Radiation monitors are also used to characterize the type of

Hand-held gamma spectrometers • Radiation monitors are also used to characterize the type of radioactive material (to identify the radionuclides!) • Gamma spectroscopy • We will now look at some of the science of this technique • The instruments are sometimes called “radionuclide identifiers” IAEA 29

A hand-held radionuclide identifier • Usually the instrument screen will display the gamma ray

A hand-held radionuclide identifier • Usually the instrument screen will display the gamma ray spectrum of the radionuclide and identify it automatically from its gamma ray spectrum Let’s look again at a gamma ray spectrum: IAEA 30

There are 103+ known elements Each of these has one or more unstable (radioactive)

There are 103+ known elements Each of these has one or more unstable (radioactive) forms known as radionuclides IAEA 31

Radionuclides are visually depicted in the Chart of the Nuclides (stable and unstable) •

Radionuclides are visually depicted in the Chart of the Nuclides (stable and unstable) • There are more than 3000 radionuclides, but only about a dozen of these are likely to find their way into the metal recycling stream IAEA 32

Gamma spectrum • Analogous to the way in which a prism will break up

Gamma spectrum • Analogous to the way in which a prism will break up visible light into a spectrum of colours, a radionuclide identification detector (RID) will use a crystal (often sodium iodide – Na. I) to produce a spectrum of gamma ray energies that are characteristic of a particular radionuclide – its gamma ray “fingerprint” so to speak’ IAEA 33

Gamma ray spectrum of IAEA 137 Cs 34

Gamma ray spectrum of IAEA 137 Cs 34

Gamma ray spectrum of IAEA 60 Co 35

Gamma ray spectrum of IAEA 60 Co 35

Gamma ray spectrum of 241 Am A typical household smoke detector IAEA 36

Gamma ray spectrum of 241 Am A typical household smoke detector IAEA 36

Gamma ray spectrum of NORM IAEA 37

Gamma ray spectrum of NORM IAEA 37

Radionuclides commonly encountered in metal recycling NAME HALF LIFE ALPHA BETA GAMMA ORIGINS Cobalt-60

Radionuclides commonly encountered in metal recycling NAME HALF LIFE ALPHA BETA GAMMA ORIGINS Cobalt-60 5. 27 years ✔ ✔ Medical, industrial Cesium-137 30 years ✔ ✔ Medical, industrial Americium-241 432 years ✔ ✔ Industrial, residential Thorium-232 14 billion years ✔ ✔ Industrial Strontium-90 29. 12 years Medical, industrial ✔ Technetium-99 m 66 hours ✔ ✔ Medical - unlikely Uranium-238 4. 47 billion years ✔ ✔ Depleted Uranium (DU), industrial Radium-226 1600 years ✔ ✔ Legacy, medical, consumer products Plutonium-238 87. 7 years ✔ ✔ Medical, industrial IAEA ✔ 38

Detectable activities of radionuclides Detectable activities depend on many factors such as: • The

Detectable activities of radionuclides Detectable activities depend on many factors such as: • The energy of the radiation being emitted • The position of the source(s) in the consignment • The quantity and density of the surrounding material - shielding IAEA 39

Standards and codes for Monitoring • Diverse standards by IAEA, ISO, ASTM, IEC, ANSI

Standards and codes for Monitoring • Diverse standards by IAEA, ISO, ASTM, IEC, ANSI • IAEA-TECDOC-1312 (2002), • IAEA Nuclear Security Series No. 1 Technical Guidance. Technical and Functional Specifications for Border Monitoring Equipment. • ISO 22188 – Monitoring for inadvertent movement and illicit trafficking of radioactive material • IEC 62244 Radiation protection instrumentation – Installed radiation monitors for the detection of radioactive and special nuclear materials at national borders IAEA 40

WARNING: portal monitors at borders will detect more than radioactive scrap! • • Patients

WARNING: portal monitors at borders will detect more than radioactive scrap! • • Patients who recently had nuclear medicine Consumer goods, commodities, class 7 (ADR) NORM material Proper transport of licensed consignments of radioactive sources, fe. g. for NDT, well-logging, medical uses etc. • Important at borders is the identification of SNM (enriched U-235, Pu-239) IAEA 41

Purposes of hand-held detectors 1. For small scrap yards and for specific materials, like

Purposes of hand-held detectors 1. For small scrap yards and for specific materials, like non-ferrous scrap or IBCs to scan incoming material. 2. Hand-held detectors are also used to verify that outgoing loads or consignments do not contain radioactive material. IAEA 42

Purposes of hand-held detectors 3. To verify an alarm of a portal or crane

Purposes of hand-held detectors 3. To verify an alarm of a portal or crane detector. • can be used for scanning a consignment in cps mode (the frequency and intensity of a sound increases when a higher radiation level is detected), or • Searching through an emptied consignment IAEA 43

Purposes of hand-held detectors 3. To locate the radioactive material in a consignment. The

Purposes of hand-held detectors 3. To locate the radioactive material in a consignment. The radioactive material (source) can be located at one or more spots or can be spread over a volume of the scrap (contaminated scrap) or combinations of these. IAEA 44

Purposes of hand-held detectors 4. To measure the radiation level caused by the radioactive

Purposes of hand-held detectors 4. To measure the radiation level caused by the radioactive material in n. Sv/hr, u. Sv/hr or m. Sv/hr • to check if direct measures are necessary to protect staff, the driver, and other people such as the public. IAEA 45

Purposes of hand-held detectors 5. To analyze the radio nuclides present • A portable

Purposes of hand-held detectors 5. To analyze the radio nuclides present • A portable gamma spectrometer or “radionuclide identification device” IAEA 46

Purposes of hand-held detectors 6) To assess if further transport of the consignment is

Purposes of hand-held detectors 6) To assess if further transport of the consignment is legally possible • Need to comply with national regulations for safe transport 7) To detect alpha- and/or beta-contaminated material • that will not be detected by portal monitors that are only gamma ray sensitive IAEA 47

Radiation alarm and investigation levels • It is not possible to provide general rules

Radiation alarm and investigation levels • It is not possible to provide general rules • The detection limit for gross-gamma counting is determined by level of local background • Expert advice and competence is required to work these out, and they must enable compliance with local safety legislation IAEA 48

How much radioactivity is there? • Despite high sensitivity and sophistication, none of •

How much radioactivity is there? • Despite high sensitivity and sophistication, none of • • these instruments indicate exactly how much radioactivity is present in a load in a vehicle (Though they can accurately assess the hazard) The only way to be sure exactly what is present, is to investigate and subject it to more careful, controlled testing, usually in a laboratory But this is time consuming and may block the facilities Careful judgements are required! IAEA 49

Pitfalls – what to watch out for • Is there NDT in the neighborhood

Pitfalls – what to watch out for • Is there NDT in the neighborhood (gamma • • radiography)? Was the driver examined or treated with radioactive material recently? NORM (bricks, gypsum, ceramics, minerals etc). Could there be enhanced background radiation, e. g. due to slag used in road building? The magnetism of pipes can interfere performance of hand-held radiation detectors IAEA 50

Pitfalls – what to watch out for • Pure beta or alpha emitting radionuclides

Pitfalls – what to watch out for • Pure beta or alpha emitting radionuclides cannot be detected at all by most portal monitors • Problems will also occur: • if different portal monitor systems are used by vendor (consignor) and buyer (consignee) • if the configuration of the load has changed during transport, thus altering the shielding and the position of activity in the load IAEA 51

Summary • • Types of monitoring and limitations Where to perform monitoring Vehicle speed

Summary • • Types of monitoring and limitations Where to perform monitoring Vehicle speed and source-vehicle geometry Portal monitors – characteristics Crane monitors – and characteristics Gamma spectrometry Hand-held detectors – purposes and characteristics • Limitations of monitoring and monitoring pitfalls IAEA 52