Préparation aux urgences Incidents nucléaires et radiologiques - Introduction Jour 10 – Présentation 1

Introduction - Objectifs Les sources de rayonnement sont une partie intégrante de notre vie axée sur la technologie Le risque d'accident est là et il n'est pas en voie de disparition Le potentiel pour les accidents qui pourraient conduire à des conséquences radiologiques sera examinée Lecture notes: Radiation sources are now an integral part of our technology-based life. As we will see later, they are used in industry, medical applications, educational institutions, etc. Although safety precautions and safety programmes are getting better all the time, the fact that more and more organisations and countries are using radiation for peaceful purposes also means that the potential for accidents is there and it is not disappearing. This potential is not limited to nuclear power stations. Indeed, there have been more accidents involving non-nuclear power practices than in the nuclear power industry itself. The potential hazard associated with nuclear power plant accidents is quite large because of the large amount of radioactive fission products “stored” in a reactor. By contrast, radiological accidents involve much smaller amounts of radioactive material, and the potential hazard is fairly limited, both in terms of geographic extent and number of people that could be affected. However, it would be a mistake to underestimate the seriousness of radiological accidents. Such accidents can lead, and have led, to serious deterministic effects, including severe injuries and death. We will examine the potential for accidents that could lead to radiological consequences. Our aim is to show that nuclear and radiological accidents can happen and that they are in fact an unavoidable consequence of advances in technology, not only in the nuclear sector, but in all industrial areas. We will also try to highlight the main features of such accidents.

Contenu Types d'accidents radiologiques Où ils peuvent se produire Conséquences des accidents Statistiques des accidents radiologiques Récapitulatif Lecture notes: In this lesson we will discuss types of radiation accidents and where they can occur. Then we will present possible consequences and some statistics regarding nuclear and radiological accidents. We will conclude with short summary of the subjects covered in the lesson.

Qu'est-ce qu'un accident de radiologique Une situation dans laquelle il ya une exposition accidentelle à des rayonnements ionisants ou une contamination radioactive L'exposition peut être réelle ou soupçonnée Lecture notes: Thousands of devices containing potentially dangerous amounts of radioactive material are used in the world. However, the safety record for the use of radioactive materials is incredibly good. There are only about two deaths or serious injuries worldwide each year from accidental radiological exposure. This is because most countries have rules requiring that dangerous amounts of radioactive material (and chemicals) be carefully controlled at all times. Emergencies involving radiological material are very similar to those involving hazardous materials. In both cases, serious health effects can result. In both cases, that hazard comes from living tissue being damaged when it is exposed to either hazardous chemicals or radiation, and the danger increases with increasing amount of material and time of exposure. There are both chemicals and radioactive materials that can be very hazardous in very small amounts and there are facilities containing large amounts of chemicals and radioactive material that could result in hazardous exposures at 100 to thousands of metres from the source. Some radiological emergencies may pose no health risk, however it may cause a major emergency because of the public’s fear of any amount of radiation and officials may be forced to respond as if there would be a true radiological hazard. This demonstrates one of the unique characteristics of events involving radioactive materials. Emergency responses may be needed not because of the radiological risk but because of the perceived risk on the part of the public, media, or officials.

Classement Général La gamme de situations d'urgence potentielles impliquant des rayonnements ionisants est énorme D'un grave accident de réacteur à des accidents impliquant de petites quantités de matières radioactives En général, les urgences peuvent être classés en deux grandes catégories: Les accidents nucléaires Les accidents radiologiques Lecture notes: The range of potential emergencies involving ionizing radiations is enormous, ranging from a major reactor accident to accidents involving small amounts of radioactive material. In general, emergencies may be classified into two broad categories: nuclear and radiological having in common the radiological nature of the threat. The arbitrary distinction made between a radiological and a nuclear emergency is explained in next slides.

Accidents Nucléaires Le terme accident nucléaire (d'urgence) s'applique à Accident du réacteur Accident dans les usines de retraitement Accidents à d'autres grandes installations nucléaires Accident impliquant la détonation avec un rendement nucléaire partielle d'une arme nucléaire Accident impliquant le cycle du combustible nucléaire et le potentiel de criticité Lecture notes: The term nuclear accident (emergency) applies to reactor accident, accident at reprocessing plants or other large nuclear facilities. It is one that involves the nuclear fuel cycle (e.g. uranium, plutonium, thorium) and the potential for criticality. An accident involving the detonation with partial nuclear yield of a nuclear weapon is also considered a nuclear accident. Typically, the potential for a health hazards is greatest for nuclear emergencies because the affected area can extend over hundreds of square kilometers and the number of people affected by stochastic impacts can be in the thousands. However, this should not undermine the importance and severity of radiological accidents, which historically have proven to be more frequent and can cause serious deterministic effects including fatalities.

Lecture notes: Examples of nuclear emergencies include Three Mile Island accident, in 1979 and Chernobyl accident, in 1986. The nuclear fuel damage that occurred during both of these events caused the release to the environment of fission products consisting of noble gases, iodine, and particulates and in the case of Chernobyl, actinides. Photo The photo shows the sarcophagus built around destroyed Chernobyl reactor unit. The photo was taken 14 years after the accident.

Où peuvent-ils se produire Le plus grand risque d'effets graves pour la santé résultant d'un rejet radioactif provient de centrales nucléaires ou des installations de stockage de grandes quantités de déchets nucléaires à partir du combustible nucléaire retraité L'installation la plus courante contenant de grandes quantités de matières radioactives est la centrale nucléaire Il ya 437 centrales nucléaires commerciales (NPP) opérant dans le monde (à partir de Janvier 2013) Lecture notes: The Chernobyl nuclear power accident resulted in the release of immense amounts of radioactive material into the environment. However the release was carried high into the atmosphere by the heat generated by the accident. This prevented very high doses close to the plant and thus prevented hundreds of early deaths or injuries off-site. As the release moved away from the reactor site, radioactive particles were deposited (on the ground, trees, people, etc.) exposing people at greater distances to significant amounts of ground contamination. Contamination levels in agricultural products more than a 1,000 km away exceeded national standards requiring restriction. The drinking of contaminated milk and eating contaminated food from family gardens has resulted in a significant increase in thyroid cancer rates among children more than 350 km from the site. Consequently, in many countries, emergency preparations have been made hundreds of km from NPPs to deal with potential food contamination resulting from a release. Nuclear power plant accidents can also result in very high doses of radiation onsite. The only early deaths resulting from nuclear power plant accidents have occurred among plant personnel or off-site fire fighters responding on-site. In the Chernobyl nuclear power plant accident 31 people responding on-site received lethal doses. This shows the importance of personnel who may respond on-site to a nuclear power plant accident having the appropriate training and equipment.

Accidents de réacteur NRX, Canada, 1952 Windscale, UK, 1957 NRU, Canada, 1957 Westing House test reactor, USA, 1960 SL-1, USA, 1961 Enrico Fermi, USA Lucens, Switzerland, 1976 Browns Ferry fire, USA TMI, USA, 1979 Chernobyl, USSR, 1986 Fukushima , Mars 2011 Lecture notes: Depending upon the criteria used there have been only 6 to 12 accidents involving research or power reactors, the most know being Windscale accident (1957), TMI accident (1979) and Chernobyl accident (1986).

Accidents radiologiques Un accident radiologique (urgence) est celui qui comporte Sources autres que le combustible nucléaire Dispersion de la matière d'une arme nucléaire sans réaction nucléaire Urgences radiologiques qui pourraient résulter d'actes délibérés, tels que les activités terroristes ou le trafic illicite Lecture notes: A radiological accident (emergency) is one that involves sources other than nuclear fuel. The most common type of radiological emergency is the dispersion and contamination of a single source (e.g. cesium) or the mishandling of a sealed source (e.g. iridium used in industrial gamma radiography). The dispersion of material from a nuclear weapon without a nuclear yield is also considered a radiological accident. Accidents with radioactive sources or material include found radioactive material or contaminated areas or items, lost or missing radioactive source, unshielded source, accidents in laboratory, transport accident involving radioactive sources or material and accidents with X-ray machines and accelerators. Radiological emergencies that could result from deliberate acts, such as terrorist activities or illicit trafficking also fall within this category.

Lecture notes: One of the worst radiological accidents occurred in Brazil in 1987. The radiological accident in Goiânia, Brazil is well documented. The IAEA published an extensive report on this accident: INTERNATIONAL ATOMIC ENERGY AGENCY, The Radiological Accident in Goiânia, IAEA Report, IAEA, Vienna (1988). Photo Demolition of a contaminated house. The photo shows the extent of the remedial work that had to be undertaken in case of the Goiânia accident. It illustrates the severity of the event.

Types d'accidents radiologiques Les accidents radiologiques peuvent être classés en trois grandes catégories: Accidents avec des sources de rayonnements ou de matières radioactives Accidents à l'extérieur du pays avec des effets transfrontaliers, et Rentrée dans l’atmosphère de satellites radioactifs. Lecture notes: One may classify radiological accidents in many different ways. The classification presented here is done from an emergency management prospective. It is consistent with the IAEA document Generic procedures for assessment and response during a radiological emergency (IAEA-TECDOC-1162, see cover page of this lesson). It is important to understand at the outset that the term “radiological accidents”, as opposed to “nuclear accidents” is used to described events that involve practices other than those associated with the fuel cycle.

Accidents avec des sources radioactives Découverte d'une source ou d’une contamination Sources dangereuses perdues ou volées Source endommagé ou perte de protection Incendie impliquant une source radioactive (s) Dispersion d'émetteur alpha Accident de transport avec des sources radioactives Accident impliquant des dispositifs nucléaires ou radiologiques (réacteur de recherche, générateur de neutrons, accélérateur…) Lecture notes: This is a broad category, which includes found source or contamination, missing source, unshielded source, accident in a laboratory or research facility, transport accident and dispersion of alpha emitters. However, initial precautions on approaching the source or contamination are the same. It may not be known a priori if there is contamination present (i.e. whether the source has been breached). Therefore, unless assurances are provided to the contrary, response to these types of accident should initially assume that contamination might be present. The extent of the hazard depends on the nature and activity of the source, which may not be known initially. Emergencies happen when there is a failure of the radiation safety controls in place (e.g. an industrial gamma radiography source left outside its shielded enclosure, or a radioactive package found in a public place). The greatest potential for serious injury arising from these sources comes principally from an unshielded high activity source. Consequences can be very serious, in some cases death, especially if the source is handled by persons who are not familiar with the hazard of radiation, or who do not know that the source is radioactive. Indeed, unshielded exposure at close quarters to the high activity sources and machines used for some industrial radiography, radiotherapy in medicine, and in sterilization units, could give rise to a lethal whole body dose in a matter of minutes. Accidents with such sources may also involve contamination if the source is damaged.

Où peuvent-ils se produire Institutions médicales Installations industrielles Institutions de recherche et d'enseignement Transport de matières radioactives Cycle du combustible nucléaire Applications sur le terrain avec la gammagraphie Lecture notes: One of the most common uses of radioactive materials is in medicine, where it has been used since about 1900. Radioactive material is used in most hospitals and in many small clinics for two basically different types of medical applications. The first is diagnosis during which a small amount of radioactive material is injected into a person. As the amount of radioactive material used does not cause harm to the person, these uses have not resulted in any serious emergencies. The second type of medical use is for treatment. During treatment, radioactive material is used, in most cases, to destroy cancer cells or tissue. If the sources can kill or destroy cancers or other organs, it can also cause injury or death if improperly controlled. Industrial radiography is another common use of potentially very hazardous amounts of radioactive material. Other portable devices containing potentially hazardous amounts of radioactive material are also used in oil exploration, mining, and construction. These portable devices are often stolen because they appear to be valuable construction equipment or are in or attached to a truck being stolen. There are also potentially hazardous radioactive devices (gauges) permanently installed in facilities to measure the thickness of steel, the levels in tanks, or flows through pipes. While several millions of packages containing radioactive material are safely transported every year, accidents do occur. There are approximately two emergency responses in the United States each day involving some type of radioactive material. Typically these involve a package carrying small quantities being punctured or crushed.

Institutions médicales Medical institutions use a great variety of radioactive sources for applications involving diagnosis and therapy. The amounts used are generally small, but emergencies can still happen, ranging from source misuse, to source misplacement of loss and to radioactive material dispersion and contamination. One of the most serious emergencies with a radioactive source used in medicine occurred in Goiánia, Brazil in 1987, one year after the worst reactor accident in Chernobyl. We will talk about the Goiánia accident later in part II of this module.

Installations industrielles The use of radioactive sources and radiation-producing machines is wide-spread in the industry. Radiation-producing machines, mainly X-ray machines and particle accelerators, produce ionizing radiation. The output, in terms of dose rate, from these machines, may be, and usually is, very much higher than that from all but the largest activity radioactive sources in use. Therefore, the potential for serious accidental exposures is normally much greater for these devices than for radioactive sources. On the other hand, the radiation output from these machines ceases when the devices are electrically switched off and discharged. Nevertheless, emergencies have occurred through faulty switches and warning signals or through activated machine parts.

Institutions de recherche et d'enseignement The use of radiation is also now quite common in the research and educational sectors. As for the applications discussed in the previous slides, the uses are varied, and the potential for emergencies covers a wide spectrum, from minor to very serious.

Transport Chaque année, environ 2,5 millions de colis de matières radioactives sont expédiées seulement aux Etats-Unis Les conséquences (surexposition grave) radiologiques graves sont rares Toutefois, la perte subséquente de sources a causé des blessures graves, par exemple, Algérie 1976 Throughout the world, many thousands of transport operations occur daily in connection with the use of radiation and radioactive materials. All forms of transport, e.g. road, rail, air and sea are involved to varying degrees. The spectrum of items transported is wide and includes nuclear industry products (including nuclear fuels and some radioactive waste materials), radiographic sources for industrial use, radiotherapy sources for medical use, equipment such as gauges, containing radioactive sources and some consumer products (e.g. smoke detectors) that are delivered in quantity and stored widely within the retail trade. By far the largest fraction of those operations is associated with the transport of radiopharmaceutical products for medical use, which are produced by a small number of manufacturers. There are also some special transportation activities, such as the movement by road, rail or air, of military-owned nuclear weapons normally incorporating plutonium; and similar movements of plutonium in specifically designed transport containers by the nuclear industry.

Transport (Exemples) These are examples of the types of transportation emergencies that could potentially occur. As seen on this slide, the consequences may vary significantly depending on the type and quantity of radioactive material being transported. For example, an accident with spent fuel can have consequences over a very wide area, with the main hazard coming from external exposure. The transport of sources such as those used in the pharmaceutical industry would have an impact over a fairly confined area, but the hazard would be both internal and external for the exposure people. The transport of plutonium is another example. Although the risk of emergencies is low, plutonium contamination could potentially be extensive (several hundreds of metres), and would present a major internal hazard. The transport of plutonium may be for peaceful or military purposes. Emergencies involving the transport of atomic weapons can lead, and have led, to the dispersal of the radioactive components of the weapon, including Pu, over a wide area. Two aircraft emergencies involving nuclear weapons have occurred: one in January 1966 in Spain and one in January 1968 near Thule Air Force Base in Greenland leading to the release of Pu oxide particles. No serious radiation exposure occurred, but the clean up process gave important lessons for decontamination and reclamation of agricultural land.

Où D'autre presque partout Sur le terrain(sources de gammagraphie) Les activités terroristes ou criminelles Le trafic illicite Dans les parcs à ferraille Sur des sites militaires Fondamentalement, dans de nombreux endroits où ils ne devraient pas être Lecture notes: There are other potential activities that could involve radiological accidents, as shown on this slide. Such accidents are complex because, in most cases, the accident could occur in totally unexpected places. Two IAEA publications are dealing with the aspects of the response to deliberate acts, such as terrorist activities: INTERNATIONAL ATOMIC ENERGY AGENCY, Preventing, Detecting and Responding to Illicit Trafficking in Radioactive Materials, Draft Safety Guide, Working Material, IAEA, Vienna (1998). INTERNATIONAL ATOMIC ENERGY AGENCY, Technical Manual on Response to Illicit Trafficking in Radiation Materials, IAEA-TECDOC-draft, IAEA, Vienna (1999).

Accidents transfrontières Impact d'un accident grave dans une installation nucléaire loin de la frontière du pays Menace plus importante: contamination de l'environnement suite au dépôt Le dépôt est plus élevé si la pluie est présente à l'heure de passage du panache Défi le plus important: la perception des médias Lecture notes: Although we said that we would not discuss nuclear power accidents, there is one aspect of such accidents that is of interest here: the transboundary, long-range impacts. When the nearest nuclear power plant is very far away (hundreds of km), the need for planning is not strongly perceived and emergency plans may not be considered important. An accident at a nuclear power plant, large fuel storage facility or at fuel reprocessing facility that results in very serious consequences off-site is unlikely, but remains possible. An accident at a such facilities located 100 to 1000 km outside a given country is unlikely to have consequences significant enough to warrant urgent protective actions such as evacuation or sheltering in that country. However, it can still have a significant direct impact on the food chain, in some cases requiring the control of national food and water supplies. It can also have an indirect impact through, for example food and supplies imported from affected countries, nationals living in affected countries or nationals wanting to visit affected countries and possibly contaminated transport vehicles entering the country. Trans-boundary effects also may result from an accident at a facility located on or near major bodies of water. Radioactive material released in such accident may be transported some distance from the accident site by water currents. Emergency plans in such cases must address the secondary impacts, such as the impacts on farming, trade and public perception.

Rentrée de satellite à propulsion nucléaire Sources d'énergie nucléaires sont utilisés dans des véhicules spatiaux tels que les satellites et sondes spatiales Les satellites peuvent transporter un petit réacteur nucléaire, générateurs thermoélectriques radio-isotopiques et unités de chauffage contiennent du plutonium Accidents de lancement ne sont pas une menace importante Rentrée accidentelle est une menace possible Accident sur le sol peut conduire à une large propagation de la contamination (e.g. COSMOS 954, Canada, 1979) Lecture notes: Nuclear power sources used in space can suffer several types of accident. For example, accidental re-entry would occur as a result of the loss of control of the space vehicle leading to the interaction of its trajectory with the earth’s atmosphere in such a way that the satellite suffers an unplanned and premature re-entry and impact on earth’s surface. A nuclear powered satellite re-entry is an accident that may normally be foreseen and even planned for several weeks or month in advance. However, some accident sequences could occur within hours. Although the exact location of impact cannot be determined, a general broad band of the earth’s surface where the impact is expected can be determined. Typically the impact area covers 100,000 km2. A satellite may contain radioactive materials in the form of a nuclear reactor or a thermal generator. The radiation risks from these materials will vary from very small to great. Surface radiation levels of up to 5000 mSv/h have been recorded from satellite debris. On 24 January 1978, COSMOS 954, a Soviet nuclear-powered surveillance satellite, crashed in the Northwest Territories. The crash scattered a large amount of radioactivity over a 124,000 square kilometre area in Canada's north, stretching southward from Great Slave Lake into northern Alberta and Saskatchewan. The clean-up operation was a coordinated event between the United States and Canada. In the estimated recovery of about 0.1 percent of COSMOS 954's power source. This incident a year later reinforced this need, and convinced officials that the time had come to set up a contingency plan to deal with peacetime nuclear accidents and events.

Risques radiologiques possibles Exposition externe Contamination interne par inhalation ou par ingestion Lecture notes: Exposure pathway is the term used to describe how the tissue in a person’s body is exposed to the radiation. The exposure pathway is important because it determines effective protective actions for the public and emergency workers and the methodology for assessing the potential radiological consequences of the material. A nuclear or radiological accident will involve the potential for exposure to radiation arising primarily from alpha or beta particles and gamma rays. In many cases, it would be a combination of those sources. Gamma radiation is penetrating and represents the most common external radiation hazard, often referred to as ‘external exposure’. Beta particles can only penetrate through small amounts of matter and thus the external dose is limited to the skin. Alpha particles are not an external radiation hazard, but can result in significant internal dose if inhaled or ingested. In addition, beta emitters can be major sources of dose to internal organs if inhaled or ingested. Once the material enters the body, different radionuclides will concentrate in different organs thus greatly increasing the dose to these organs. If the material is airborne it can be inhaled. Airborne radioactive materials can result from an accident at a facility (e.g., nuclear power plant), a fire containing radioactive material, or resuspension of material deposited on the ground. Resuspension in most case is not an important source of dose. Ingestion is often a very important source of dose, occurring when contaminated food is eaten or from contamination on the hands. Ingesting milk contaminated by the Chernobyl accident has caused many cases of thyroid cancer in Belarus and Ukraine. Very high, possibly fatal doses have resulted from ingestion of contamination from a ruptured source.

Conséquences possibles sur la santé Syndrome d'irradiation aiguë Brûlures locales Lésions associées Décès Risque accru d'effets tardifs (cancer par exemple) Lecture notes: Radiation-induced effects of concern in emergency response fall into two general categories, termed deterministic and stochastic effects. The function of most organs and tissues of the body is unaffected by the loss of a small or sometimes even a substantial number of cells. If enough cells are lost, however, and the cells are important, there will be observable harm, reflected in a loss of tissue function. The probability of causing such harm is zero at small doses of radiation, but above some level of dose (the threshold) it increases to unity (100%). Above the threshold, the severity of the harm increases with dose. This type of effect is called deterministic, because it is sure to occur if the dose is large enough and is higher than threshold. Examples of deterministic effects are temporary or permanent sterility in the testes and ovaries; depression of the effectiveness of the blood-forming system, leading to a decrease in the number of a blood cells; and cataracts. A special case of deterministic effect is the acute radiation sickness resulting from acute whole body irradiation. Sometimes irradiation will not kill the affected cells, but may only alter them. A viable but modified somatic cell may still retain its reproductive capacity and may give rise to a clone. If the clone is not eliminated by the body’s defence mechanisms, after a prolonged and variable period of delay termed the latent period, it may result in the development of malignant conditions, usually termed cancers, which are the principal late somatic effects of exposure to radiation. In contrast to deterministic effects, it is assumed that there is no threshold of dose below which stochastic effects (e.g., cancer) cannot occur. These effects do not occur in every exposed individual; the probability that an individual or one of his or her descendants may develop one of these effects increases with the dose received. Thus, even if the dose is very small, the person still has a chance, albeit a very small one, of incurring such an effect. Photo: Local burns due to handling the source by hand

Autres conséquences possibles Contamination de l'environnement Pertes économiques Psychologique Juridique Lecture notes: Even in the absence of a direct human health impact, radiological accidents could result in serious consequences. For example, environmental contamination could result in a significant cost impact through the need to (for example): decontaminate; provide alternate food supplies if food was contaminated; relocate people who live in or near the affected area; engage in an extensive public information program to reassure the public, minimize the psychosocial impacts and maintain confidence in the government authorities; and present the degeneration of the event into a crisis. Photo Checking the dose rate in the evacuated town of Pripyat located just 3 km from the damaged Chernobyl reactor. About 50.000 persons were evacuated and they never returned back to their homes.

Récapitulatif Les accidents radiologiques peuvent se produire Conséquences radiologiques graves sont rares, mais ils peuvent se produire Effets stochastiques Blessures graves Décès Par conséquent, les plans d'intervention d'urgence sont nécessaires Lecture notes: Let’s summarize the main subjects we did cover in this session. Despite considerable development in the techniques of radiation safety, accidents may happen, which might injure people and contaminate the environment. Following a high-level accidental exposure to radiation, injuries evolve over time in distinct phases. The length and time of the occurrence of the phase depend on the dose. Low doses do not produce observable effects. The importance of emergency response plans and effective introduction of protective actions in an accident cannot be overstated.

Où trouver plus d'informations Generic Procedures for Assessment and Response During a Radiological Emergency, IAEA-TECDOC-1162 (2000) Lessons learned from Accidents in Industrial Radiography, IAEA Safety Reports Series No.7 (1998)