Panorama des sources utilisées pour la radiographie industrielle et accidents Jour 5 – Présentation 3.

Panorama des sources utilisées pour la radiographie industrielle et accidents
Jour 5 – Présentation 3

Objectifs Comprendre :
Les différentes applications de la radiographie industrielle Risques d’accidents associés à l’utilisation de sources de rayonnements pour la radiographie industrielle. Mention each topic above placing emphasis on the point that industrial radiography can be a hazardous practice because there is always a potential for serious injury.

Contenu Les avantages liés à l’utilisation de sources de rayonnements en radiographie industrielle; Les risques potentiels dus à l’absence ou au manque d’efficacité d’un programme de protection et de sûreté satisfaisant et approprié; Les conséquences d’accidents radiologiques. Mention each topic above placing emphasis on the point that industrial radiography can be a hazardous practice because there is always a potential for serious injury.

Qu’est-ce que la radiographie industrielle ?
La radiographie industrielle est : Un processus de tests non destructifs pour évaluer la qualité d’un composant ou bien d’un produit; Très souvent employé pour le contrôle qualité de fabrication des métaux utilisés dans le secteur de l’énergie; Également utilisée pour le contrôle de nombreux autres produits. Explain the purpose of industrial radiography (Why do the companies carry out industrial radiography ? – What is the benefit ?). Explain some of the common applications but also note that its application is very diverse. Give examples of the common uses and some of the diverse applications (eg underwater radiography, radiography of electronic circuit boards, plus other examples).

Principes d’imagerie Explain that industrial radiography involves the use of penetrating gamma or X-radiation to examine materials and parts for imperfections. Using the diagram explain that an x-ray generator or radioactive isotope is used as a source of radiation. Radiation is directed through a part and onto film or other detector. The resulting image or radiograph shows both internal and external features of the part. Possible imperfections are indicated as density changes in the film in the same manner as an medical X-ray can reveal broken bones.

Appareils utilisés en radiographie industrielle.
Des connaissances particulières sont requises à propos :- Des dispositifs émettant des rayonnements à partir de sources (substances radioactives et appareils à rayons X); Du type et de l’activité de chaque radionucléide utilisé; Du cadre dans lequel sont utilisées ces sources : laboratoires, unités de fabrication, mines…; Du dimensionnement de l’installation en fonction des caractéristiques du dispositif et des procédures d’utilisation, essentielles pour la protection des travailleurs et du public. Go through the topics above mentioning there is a wide range of equipment types and locations where it may be used. Give examples of the range of isotopes used (Ir-192, Co-60, Se-75 etc). Again highlight the potential for serious injury because industrial radiography relies heavily on the radiographer being vigilant with safety and use of safe working procedures.

Histoire Roentgen a découvert les rayons X en 1895;
Très vite, les tubes à rayons X furent fiables; Coolidge invente le tube à rayons X à cathode chaude en 1913; 200kVp mis au point dès 1922. Discuss briefly the early times, changes in equipment and standards or protection. In his discovery in 1895, Roentgen found that the x-rays would pass through the tissue of humans leaving the bones and metals visible. One of Roentgen's first experiments late in 1895 was to x-ray the hand of his wife, Bertha. However, it can be argued that the first use of x-rays was for an industrial (not medical) application as Roentgen produced a radiograph of a set of weights in a box to show his colleagues. Prior to 1912, x-rays were used little outside the realms of medicine, and dentistry, though some x-ray images of metals were produced. The main reason that were not used in industrial application before this date was because the x-ray tubes (the source of the X-rays) of that period broke down under the voltages required to produce x-rays of satisfactory penetrating power for industrial purposes. However, that changed in 1913 when high vacuum x-ray tubes with a heated filament as the source of electrons, designed by Coolidge, became available. The high vacuum tubes were an intense and reliable X-ray sources, operating at energies up to 100,000 volts. In 1922, industrial radiography took another step forward with the advent of the 200,000-volt x-ray tube that allowed radiographs of 7-8 cm thick steel parts to be produced in a reasonable amount of time. In 1931, the General Electric Company developed 1,000,000 volt x-ray generators.

Histoire (suite) Dans les années 30 et 40, le 226Ra était utilisé.
Après la 2ème guerre mondiale, le 60Co et l’192Ir furent utilisés Discuss briefly the early times, changes in equipment and standards or protection. Industrial radiography sources used in the 1930s and 1940s were Ra because no other radionuclides were then available of sufficient strength. The capsules used contained approximately 3.7 GBq (0.1 Ci). After World War II, Ir-192 and Co-60 replaced radium. When used, the radioactive source would be placed on one side of the weld or metal casting being "x-rayed," while a sheet of photographic film was placed on the other side. Exposure times were quite long, e.g., one hour to as much as four days. The source was either handled with a long pole ("fish pole") or tied to a cord. The latter method, for example, would allow it to be pulled through a long pipe. In the picture on the left, the source is being removed from its shield ("pig"). The photo on the right shows the source being held at the end of a fish pole. The long exposure time and an unsteady hand often resulted in a blurry x-ray image.

Appareils utilisés en radiographie industrielle
Les plus répandus Les projecteurs de source gamma; Générateurs de rayons X directionnel; Générateurs de rayons X panoramiques; Analyseurs utilisant des rayons X; Analyseurs utilisant des rayons gamma; Sources de contrôle; Et aussi … Bêtatron; Accélérateur linéaire, Radiographie neutron; Fluorescence… Explain that the a range of equipment types used for industrial radiography has grown, each with there own advantages and disadvantages that influence what equipment the radiographer may use for any particular application. Discus some of the different potential radiation hazards that they present. Discuss briefly the primary types used and that they may never encounter some types of equipment but they should nevertheless be aware of their existence and application.

Appareils émettant des rayons X
Les 3 composants principaux sont : Le tube à rayons X; L’interface de réglage des rayons; Les câbles haute tension. Discuss the main components of the equipment Discuss application of the different types of equipment presented in the slide (directional, panoramic and CP x-ray devices). The potential for serious injury when using x-ray equipment is very apparent when one considers the dose rate that x-ray equipment can produce. As an a Rigaku 250EGS2 250 kVp directional x-ray unit operating at 250 kVp and 5 mA produced a dose rate in air of approximately 1.2 Gy/min at 30 cm (with 2 mm Al filter). With only the 1mm Be window the dose rate was approximately 10.6 Gy/min at 30 cm. [Source: Radiation Health Branch, Department of Health Western Australia]

Bêtatron Caractéristiques particulières
Compteurs de mesures avec une réponse appropriée; Formation de l’utilisateur; Protection; Discuss that application to import and use uncommon equipment may be encountered for a special project that requires the particular advantages it has to offer. Discuss the proposal to use the betatron and the special considerations that it warrants (who would operate it, additional shielding , distance, calibrated survey meter ?).

Analyseurs utilisant des rayons gamma
Applications spéciales : Canalisations externes; Canalisations off-shore (sur une barge); Contrôlé à distance avec une source séparée “de contrôle”, par ex. 137Cs. Discus the main elements and purpose of the crawler equipment and where they may typically be used (onshore and offshore). Briefly discuss the potential accidents with this type of equipment and how vigilant operation is required.

Radioactive Sources and some properties
The range of HVLs and TVLs demonstrates the range of radiation energies emitted by the listed nuclides. The highest energy gamma radiation in this table is emitted by Co-60. Ideally, the choice of nuclide for industrial radiography depends on the nature of the material being radiographed. However, practical issues of cost, half life, containment (weight) and shielding make Ir-192 the most commonly used source.

Projecteur de source type
Boîtier de commande Câble de commande et gaine(s) Porte-source Source gamma en position de stockage sûre et sécurisée Source gamma en cours d’utilisation, source en dehors du projecteur Collimateur Gaine d’éjection de la source Enceinte protégée de stockage de la source Discuss briefly the principle of operation. Survey, connection, checking connection, set up item to be radiographed, crank out to expose, survey, crank in to shield, survey , lock off between exposures, diss-assembly and stowage, survey etc. Discuss briefly why this is the main type of design used throughout the world. Discuss briefly the main problems with this type of equipment if adequate procedures are not in place and followed.

Après une exposition au feu
Dispositifs contenant des sources Les dispositifs contenant des sources doivent être conformes aux normes pour que l’exposition des utilisateurs et du public soit maintenue aussi basse qu’il est raisonnablement possible (ALARA) Après une exposition au feu Discuss briefly that equipment design standards play a major role in limiting accidents that may cause serious harm. Highlight that poor operational procedures and safety programs are probably the major contributor to accidents involving industrial radiography equipment. Discuss briefly the incident involving the gamma projector in the slide. The gamma projector came from a industrial radiography practice that experienced a severe fire. Despite the whole building being destroyed by the fire, the container remained intact and did not loose any shielding. It can no longer be used for radiography. L’enceinte protégée de stockage de la source doit être dimensionnée pour différents types d’incidents et d’accidents. Le blindage de ce conteneur (à droite) est resté intact après un grave incendie dans les locaux autorisés

Fluoroscopie Écran de visionnage de l’image
Ordinateur et logiciel pour la capture de l’image, son traitement et l’enregistrement Enceinte d’irradiation Real-time radiography is a well-established method of NDT having applications in automotive, aerospace, pressure vessel, electronic, and munition industries, among others. The use of RTR is increasing due to a reduction in the cost of the equipment and resolution of issues such as the protecting and storing digital images. Perhaps the main advantage of RTR is the increased inspection speed. There are however, disadvantages such as set up costs and image resolution that make the method unlikely to replace film radiography just yet. In the above picture, RTR is used inside a shielded and interlocked cabinet. The radiation safety advantages of this configuration are very clear. Perhaps in the not to distance future it will become an affordable widespread method but radiography will still be required in field locations where the advantages of shielded and interlocked cabinets can not be put to use. Panneau de contrôle du générateur de rayons X

Accidents de radiographie industrielle
48 accidents de radiographie industrielle1 ont été déclarés à l’autorité de sûreté nucléaire américaine, the Nuclear Regulatory Commission, entre 1971 et 1980. Depuis de nombreuses expositions graves ainsi que des cas de décès ont été déclarés et ont fait l’objet d’une enquête approfondie. Discuss the above material. Footnote 1 - involving overexposure greater than 5 rems to the whole body or 75 rems to a part of the body. (Ref: NUREG/BR-0024). Many accidents may go unreported because those responsible fear the legal consequences. Highlight some of the more well known recent industrial radiography accidents. February 1999 Peru a 192Ir industrial radiography source was picked up by a welder resulting in sever burns to his buttock. July 2000 Cairo a 192Ir industrial radiography source was stolen resulting in the death of a man and his son. Eight people face up to life in prison. Highlight that it is likely a large number of less severe accidents go unreported. 1impliquant des doses corps entier supérieures à 50 mGy ou à 750 mGy pour une partie du corps. (Réf: NUREG/BR-0024). Plusieurs accidents ont pu ne pas être déclarés par les responsables des activités en raison des conséquences.

Rapport de sûreté de l’AIEA Séries n°7. Leçons tirées des accidents de radiographie industrielle. 43 cas; 9 impliquant des personnes du public ou bien des travailleurs non exposés.

Conséquences graves d’une exposition d’un travailleur non exposé. La personne utilisant un appareil de radiographie n’a pas vérifié avec un appareil de mesure que la source était rentrée dans son container de stockage. Day 15 Source de 185 GBq 192Ir transportée dans la poche d’une chemise pendant 90 min. Dose estimée à la peau : 30 Gy; Dose corps entier : 2-5 Gy The Radiological Incident in Gilan IAEA Report 2002 During the night of 23–24 July 1996, industrial radiography was undertaken at the Gilan combined cycle fossil fuel power plant, situated 600 km north of Tehran. Welds on a boiler and pipes located at a height of 6 m above the plant floor were radiographed with a 185 GBq 192Ir source. At the end of the shift, at around 03:00 on 24 July 1996, the iridium source became detached from its drive cable, reportedly due to failure of the lock on the radiography container. This resulted in the source falling 6 m into a trench which was surrounded by a 1 m high wall made of concrete blocks. As the source was shielded by the concrete, its loss was not detected by the radiography team when they finished work and they assumed that it had been safely returned to its container, as usual. K.Z. was climbing up a ladder carrying heat insulation material when he noticed a shiny metallic object (the 192Ir source) lying in the trench. Once down the ladder, he picked up the source and put it in the right breast pocket of his coveralls. Over the next 1.5 h, K.Z. reportedly removed the source from his pocket to inspect it and then returned it to the pocket on a number of occasions. At around 09:30 he started to experience dizziness, nausea, lethargy and a burning feeling in his chest. Believing that the object was a possible cause of his symptoms, he put it back in the trench and then went to the workers’ rest room. Relate this type of injury to actual accidents that have happened, primarily through poor operator training, failure to use survey meters and other warning devices.

De mauvaises dispositions pour assurer la sécurité des sources peuvent entraîner de sévères conséquences, jusqu’à la mort. Source de 137Cs utilisée en radiographie industrielle; Argentine 1968. A number of deaths have resulted from the radiation doses received following prolonged exposure to industrial radiography sources. The above picture follows an accident in 1968 (May 3 - 4) where a worker carries Cs-137 radiography source in his pockets; Buenos Aires (Argentina). The man latter had both legs amputated.

Source de 137Cs utilisée en radiographie industrielle; Argentine 1968. Doses 17000 Gy (localisée) 1 - 8 Gy (organes internes) 0.6 Gy (tête) A number of deaths have resulted from the radiation doses received following prolonged exposure to industrial radiography sources. The above picture follows an accident in 1968 (May 3 - 4) where a worker carries Cs-137 radiography source in his pockets; Buenos Aires (Argentina). The man latter had both legs amputated.

Yanango, Perou 1999 1.37 TBq 192Ir. 2 jours après l’accident, une cloque s’est formée sur le haut de la cuisse. The above picture follows an accident in Peru on 21 February The worker carries Ir-192 radiography source in his rear pocket for several hours. The source, in the man’s pocket, was taken on a bus to his home where his wife and children were also exposed. The wife sat on the man’s trousers with the source in it for between 5 to 10 minutes while breastfeeding a baby.

Source insuffisamment sécurisée, perdue pendant 6 heures. The above picture follows an accident in 1999 () where a welder carries Ir-192 radiography source in his rear trouser pocket; dose near contact leads to amputation of one leg; Yanango (Peru). IAEA A 1.37 TBq 192Ir was “lost” from its shielded container. The source was picked up by an employee at the site where radiography was taking place and carried in his pocket for several hours. Some 5 hours later he experienced pain in the back of his right thigh. His wife later noted reddening of the skin. She was also exposed when she sat on his jeans (which contained the source) for 5‑10 mins while breastfeeding. Two other children were within 2 – 3 metres of the source for around 2 hours. The loss of the source was not apparent to the industrial radiographer until some 6 hours after it was picked up by the employee when a series of routine exposures resulted in unexposed films. The skin dose (at 1 cm) to the employee’s leg was estimated at around 10 kGy. His right leg was later amputated at the hip and the anal sphincter and basal part of the scrotum were resected. His wife developed an ulcerative lesion on the lower back. Although the cause of the “loss” of the source remains unknown, it is clear that the industrial radiographer failed to ensure the security of the source container and failed to properly use the radiation survey devices available to him. This type of incident has been reported elsewhere and could occur in any country. Prevention depends solely on appropriate training and strict observance of prescribed safety procedures by the industrial radiographer. Also relate accidents in Iran 1996, Morocco 1984 Algeria and more recently in Egypt 2000 etc. Dose à la peau à 1 cm estimée à 10 kGy. La jambe droite a été amputée. La femme de ce travailleur et ses 2 enfants ont été exposés.

Conséquences des accidents
Des effets déterministes graves : Mort, perte de membres, érythèmes. Augmentation des risques stochastiques : Cancer. Contamination de l’environnement; Conséquences sociales et économiques. Discuss in summary the above points as have been illustrated in the previous slides.

Origines des accidents
Origines identifiées ayant contribué aux accidents : Cadre réglementaire non défini ou bien insuffisant : Autorisations; Inspection; Mesures de police, infractions et sanctions pénales; Culture de sûreté absente ou insuffisamment développée Encadrement et direction; Contrôle de qualité; Formation et qualifications des travailleurs.

Origines des accidents (suite)
Les appareils de mesure n’ont pas été utilisés Contrôles réglementaires absents ou mal adaptés Formation insuffisante ou inexistante Défaillance de l’équipement ACCIDENT Discuss the above typical causes of accidents. Each has the potential to result in dangerous situation. However, as will be learnt later during this week, some of the above factors can be managed while others are outside the scope of management because they are not necessarily recognised as a problem. Programme de protection et de sûreté insuffisant ou absent Les procédures n’ont pas été suivies

Origine des accidents (suite)
Contrôles réglementaires absents ou bien mal adaptés ACCIDENT L’autorité de réglementation possède :- Un système d’autorisation mal adapté; Un système d’inspection, incluant le champ couvert ainsi que leur suivi, insuffisant. Discuss the features that may be representative of a lack of regulatory control giving examples of the possible consequences.

Formation insuffisante ou inexistante ACCIDENT Le manque d’information, de formation, (et de formation en continu) a les conséquences suivantes :- les travailleurs ne sont pas qualifiés et n’ont pas connaissance des risques auxquels ils sont exposés ; les procédures d’urgences sont peu connues et mal comprises. Discuss that many accidents have been a result of poor or no training.

Programme de protection et de sûreté insuffisant ou absent L’absence de programme de protection et de sûreté provient: d’un encadrement et d’une direction peu impliqués; du manque de culture de sûreté. A lack of safety program within an industrial radiography company may also be associated with insufficient regulatory control.

Si les procédures de sûreté n’ont pas été appliquées, cela provient :- du manque de culture de sûreté; d’un système de contrôle défaillant; d’une formation peu adaptée. ACCIDENT One of the more serious factors that may lead to accidents is failing to follow safety procedures – particularly failing to make sufficient and proper radiation surveys. Accidents that result from this case can often result in serious injuries because there can often be a time lag before it is recognised that an accident has occurred. . Les procédures n’ont pas été suivies

Défaillance de l’équipement Une défaillance de l’équipement peut provenir :- d’une maintenance recommandée par le fabricant de l’équipement inadaptée ou bien non définie; d’une mauvaise utilisation de l’équipement; d’une utilisation de l’équipement au-delà de ses critères de dimensionnement. Equipment failure can lead to accidents but if properly managed they can be controlled before the accident becomes serious. Example, a common ‘equipment failure’ involves a source holder becoming detached from the control cable. This is often the result of wear of the couplings and can result in the source being unconnected in an exposed position. Source retrieval can be accomplished safely provided a safety plan is adopted and followed.

Les appareils de mesure n’ont pas été utilisés Si les appareils de mesure n’ont pas été utilisés, cela provient : ACCIDENT du mauvais état des appareils ou de leur inadéquation pour la mesure prévue ; Explain that accidents involving failure to use survey meters can have serious consequences because the operator is unaware whether the source is in a shielded condition or not and therefore, does not necessarily know where the source is located. d’une formation insuffisance des utilisateurs; du manque de temps pour réaliser la mesure (chantiers trop rapprochés dans le temps, pression sur les employés...) du manque de culture de sûreté.

Principes d’utilisation des sources de rayonnement
Les sources de rayonnement : Sont largement utilisées; Présentent des avantages pour certaines pratiques; mais Peuvent être à l’origine de conséquences graves. Leur utilisation demande la mise en place de dispositions pour : Culture de sûreté } La formation; La maintenance Le contrôle.

Les risques Les avantages
Principes d’utilisation des sources de rayonnement Principe de justification Les risques Les avantages Une activité nucléaire doit être justifiée par les avantages qu’elle procure, rapportés aux risques inhérents à son utilisation (exposition, contamination…)

Références Radioprotection et sûreté des sources de rayonnements : normes fondamentales internationales de sûreté. Prescriptions générales de sûreté Partie 3. (Normes de sûreté de l’AIEA N° GSR Part 3 (Interim), Vienne 2011. Emergency planning and preparedness for accidents involving radioactive materials used in medicine, industry, research and teaching. IAEA Safety Series No. 91, 1989. Contrôle réglementaire des sources de rayonnements , Normes de sûreté de l’AIEA Guide de sûreté No. GS-G-1.5, Vienna (2004). IAEA, Lessons learned from accidents in industrial radiography, (reports in) Safety Reports Series. IAEA, Accident reports. MODIFIED 35 35

Exercice Considérez les équipements de radiographie industrielle suivantes; portables à rayons X; fixes à rayons X; gamma fixe; gamma portable Qui a le plus grand potentiel de causer des dommages graves à l'utilisateur et au public? Pourquoi? Course participants should be able to recognise the higher risk in use of that portable gamma radiography equipment. The higher risk are associated with the field use of the equipment where public access may be possible, the design which often involves the source leaving a shielded position and the high reliance of operator following safe procedures.

Panorama des sources utilisées pour la radiographie industrielle et accidents Jour 5 – Présentation 3.

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Panorama des sources utilisées pour la radiographie industrielle et accidents Jour 5 – Présentation 3.

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