Radiation Emergency Situations Anna Maria Motoc National Research

Radiation Emergency Situations Anna Maria Motoc National Research Institute for Radiobiology and Radiohygiene

Forms of ionizing radiation Directly ionizing Particulate radiation consisting of atomic or subatomic particles (electrons, protons, etc. ) which carry energy in the form of kinetic energy of mass in motion Indirectly ionizing Neutron radiation Electromagnetic radiation in which energy is carried by oscillating electrical and magnetic fields travelling through space at speed of light

Origin of radiation Radioactive decay Modes of Radioactive Decay Ø alpha decay producing alpha particles, Ø beta minus decay producing electrons, Ø beta plus decay producing positrons, Ø electron capture, Ø gamma decay producing gamma rays, Ø internal conversion producing energetic electrons, Ø spontaneous fission producing neutrons and fission fragments.

Fission

Nuclear reaction and energy production

What is a radiation accident? n A situation in which there is an unintentional exposure to ionizing radiation or radioactive contamination n Exposure may be real or suspected

Radiation accidents n Ø Ø • Radiation accidents include radiological and nuclear accidents It is more appropriate and practical to use the term “nuclear and radiological emergency” for purposes of planning, preparedness and response

Main types of radiation accidents: involved groups n n n Accidents during work - workers n radiography n irradiators (sealed sources and accelerators) Accidents due to loss of control over radiation sources - public exposure n radiotherapy n orphan sources Accidents in medical applications - patients n misadministration of radiopharmaceuticals n miscalculation of the dose for radiotherapy

Where do radiation accidents occur? n n n n Irradiation facilities Material testing (sealed sources) Material testing (X-ray devices) X-ray and radiotherapy devices (medicine, research) Isotope production facilities Unsealed radionuclides (medicine, research) Nuclear reactors Transportation

Scale of radiation accidents n Small scale radiation accidents n usually involve a small source term and few people often come to light from observations by primary care physicians (mainly GPs) Large scale radiation accidents n usually involve a large source term and many people irradiated/contaminated n n n require specialist treatment in both primary and secondary medical facilities n can lead to widespread public health action to mitigate the effects of contamination.

Industrial radiography n. Inspection of products (non-destructive testing). n Gamma radiation sources (Ir-192 or Co-60) are used to inspect a variety of materials. n The vast majority of radiography concerns the testing and grading of welds on pressurized piping, pressure vessels, high-capacity storage containers, pipelines.

Gamma radiography 1. 5 TBq Ir-192 At 1 m. from the source: 150 m. Gy/h = 2. 5 m. Gy/min At 1 cm. : 25 Gy/min At 3 mm. : 250 Gy/min ≈ 4 Gy/s Threshold dose for radiation skin burns: 3 -4 Gy

The acute dose-dependent effects of beta radiation on skin 0– 6 Gy no acute effect 6– 20 Gy moderate early erythema 20– 40 Gy early erythema in 24 hours, skin breakdown in 2 weeks 40– 100 Gy severe erythema in less than 24 hours 100– 150 Gy severe erythema in less than 4 hours, skin breakdown in 1– 2 weeks 150– 1000 Gy blistering immediate or up to 1 day

INES International Nuclear and Radiological Event Scale

Examples of events at nuclear facilities Ø 7 Chernobyl, 1986 — Widespread health and Environmental effects. External release of a significant fraction of reactor core inventory. Ø 6 Kyshtym, Russia, 1957 — Significant release of radioactive material to the environment from explosion of a high activity waste tank. Ø 5 Windscale Pile, UK, 1957 — Release of radioactive material to the environment following a fire in a reactor core. Three Mile Island, USA, 1979 —Severe damage to the reactor core. Ø 4 Tokaimura, Japan, 1999 — Fatal overexposures of workers following a criticality event at a nuclear facility. Saint Laurent des Eaux, France, 1980 — Melting of one channel of fuel in the reactor with no release outside the site.

Examples of events involving Radiation Sources and Transport n 5 Goiânia, Brazil, 1987 — Four people died and six received doses of a few Gy from an abandoned and ruptured highly radioactive Cs-137 source. n 4 Fleurus, Belgium, 2006 — Severe health effects for a worker at a commercial irradiation facility as a result of high doses of radiation. n 3 Yanango, Peru, 1999 — Incident with radiography source resulting in severe radiation burns. Ikitelli, Turkey, 1999 — Loss of a highly radioactive Co-60 source. n 2 USA , 2005 — Overexposure of a radiographer exceeding the annual limit for radiation workers. France, 1995 — Failure of access control systems at accelerator facility. n 1 Theft of a moisture-density gauge.

Radiation accidents by cause n Radiation accidents with unknown origin and late recognition: (e. g. Goiania, 1987; Estonia, 1994; Georgia, 1997 & 2001; Turkey, 1998/99; Thailand, 2000; Egypt, 2000 ) n Accidents with initially known radiation origin: (e. g. Iran, 1996; Peru, 1999 ) n Accidental exposure in medical applications: (e. g. Spain, 1990; Costa Rica, 1996, Panama, 2001) n Criticality accidents: (e. g. Sarov, Russia, 1997; Tokaimura, Japan, 1999) n Major nuclear accident: Chernobyl, USSR (1986)

Radiological accident in Goiania 137 Cs-accident, Goiânia, Brazil September 13, 1987 Goiânia Rio de Janeiro Angra NPP Sao Paulo

Accident description

Source 137 Cs. Cl (caesium chloride) 50. 9 TBq (1375 Ci) main gamma: 0. 66 Me. V main beta: 1. 17 Me. V T 1/2=30 years

Contamination risk n External contamination: radioactive material, as dust, solid particles, aerosols or liquid, becomes attached to victim’s skin or clothes n Internal contamination: occurs when people ingest, inhale, or are injured by radioactive material Metabolism of non-radioactive analogue determines radionuclide’s metabolic pathway n

External contamination measurement n n n Proper monitoring of patient can detect and measure alpha, beta or gamma emitters; radiation type depends on isotope in contaminant Alpha Monitor

Radiological triage 112 000 persons monitored 249 identified contaminated 120 only clothing and shoe contamination 129 internal contamination 50 subjected to direct medical surveillance

Decontamination

Technical management of accident 85 residences (houses) had significant level of contamination, 41 evacuated, 4 demolished

Medical aspects 250 persons exposed 50 persons WB exposure or local radiation injury 14 bone marrow depression 8 ARS 4 died 28 local radiation injury

Contamination sources in nuclear accidents

Inhalation n Soluble particles (3 H, 32 P, 137 Cs) absorbed directly into circulatory system n Insoluble particles (Co, U, Ru, Pu, Am) are cleared by lymphatic system or by mucociliary apparatus above alveolar level. Most secretions reaching pharynx swallowed, enter gastrointestinal system

Ingestion §All swallowed radioactive material enters digestive tract Ø primarily from contaminated food and water Ø secondarily from respiratory tract §Absorption from the gastrointestinal tract depends on chemical make-up and solubility of contaminant • Elements of high absorption: • radium (20%) • strontium (30%) • tritium (100%) • iodine (100%) • caesium (100%)

Internal contamination measurement : direct methods Whole body counters Thyroid uptake system

Chernobyl reactor accident Total contaminated surface (> 1 Ci/km 2): 1 000 km 2 Near zone (<100 km): deposition of heavy particles ( Sr, Pu. . . Far zone (up to 2000 km) : deposition of volatile elements (I, Cs)

Radionuclides released

Main radionuclides contributing to health effects n iodine - 131 n n n volatile T 1/2: 8 day disappears from environment in 2 months inhalation and ingestion concentrates in thyroid n caesium - 137 n n n volatile T 1/2: 30 years stays long in environment body elimination in about 100 days homogenous distribution in all organs and soft tissues

Thyroid cancer and ionizing radiation n n Chernobyl accident shows that exposure to iodine isotopes may cause increase in prevalence of thyroid carcinoma In 1990 -2000 about 1800 thyroid cancers observed in 18 million children and adolescents, i. e. under 18 years old, living in the most contaminated areas of Belarus, Ukraine and Russia Childhood thyroid cancer around Chernobyl in 1986 -1998 (children <15 years old at diagnosis) diagnosis

Leukemia and other cancer n No significant increase in leukemia or cancer other than thyroid; solid tumor observed in Chernobyl cleanup workers n Tendency for elevated leukemia rates, however, among those who received significant doses while working on site in 1986 and 1987. So far statistically significant leukemia excess reported for Russian cleanup workers only

Chernobyl conclusions n n n Radiation burns frequent Burns over 50% of body surface led to death in 19 of 28 cases Internal contamination present in most patients but was significant in few Sepsis was uniform cause of death Severe multiple necrotic. BMT –very limited indication Some radiation burns did not re- ulcerative radiation burns in Chernobyl fireman on Day 40 epithelialize, required surgery after the accident

Japanese Nuclear Accident (March 11/2011) n n Sendai earthquake and tsunami Fukushima nuclear accident.

n n The Fukushima I Nuclear Power Plant (Dai-ichi), is a nuclear power plant located in the town of Okuma, Japan. The plant consists of six boiling water reactors. These light water reactors have a combined power of 4. 7 GW, making Fukushima I one of the 25 largest nuclear power stations in the world. Among the 6 reactors at Tokyo Electric Power Company's (Tepco's) East coast Fukushima Daiichi NPP, reactors 1, 2 and 3 were in operation when the magnitude 9. 0 earthquake struck.

A boiling water reactor (BWR) splits atoms to release nuclear energy. This energy is removed from the reactor core during normal operation and used to spin turbine blades connected to a generator that produces electricity. A nuclear power plant has entire systems designed to match the energy produced by the reactor core with the energy removed. This balance is extremely important because the reactor core can overheat and release large amounts of radioactivity when more energy is produced than removed.

Tsunami - the 7 to 10 meter wave hit the coast in the plant area after the earthquake - have caused the failure of the cooling system (heat sink). The cooling of the reactors then depended on the vaporisation of the water available in the reactor vessel and in the other reservoirs in the plant. The steam produced inside the reactor vessel was condensed in the condensation vessel, whose temperature and pressure began to rise slowly.

To vent some steam outside this vessel in order to reduce the pressure. Unfortunately, the steam appeared to contain some hydrogen, produced by the oxidation of the overheated fuel cladding. This hydrogen, vented in the top part of the reactors buildings, exploded when it came into contact with air. The presence of hydrogen and of volatile fission products like iodine and caesium in the released steam suggested that the temperature of the fuel was such that severe damage of the fuel claddings might have taken place inside the reactor vessel.

n Pumping seawater into the reactors was decided as an ultimate measure to cool the reactors, to maintain the integrity of the reactor and containment vessels, and to confine the radioactivity. This procedure seems to have succeeded so far in reactors 1 and 3. A confinement leak in reactor 2 containment structure has been dreaded, but was not confirmed as of March 18 th. n As another dramatic consequence of the earthquake, the storage pools which contain the spent fuel of reactors lost some of their water. n The spent fuel rods might have been insufficiently cooled and exposed to air. This might have resulted in heating of the spent fuel, with severe degradation of the fuel zirconium alloy cladding and subsequent release of part of the volatile fission products it contains into the atmosphere. A high level of radioactivity was measured around reactor 4. n

Protective actions n Radiation monitoring Ø Ø Dose rate and beta-gamma contamination Radioactive releases (concetration in air) Control of the external and internal contamination of the population Control of the contamination of the environment (foods and drinking water, see water)

Status after the accident Results of the measurements : -Measurement of gamma dose rate and beta-gamma contamination were taken at more locations. The dose-rate results ranged from 2 -160 microsieverts per hour, which compares to a typical natural background level of around 0. 1 microsieverts per hour. -High levels of beta-gamma contamination have been measured between 16 -58 km from the plant. -Available results show contamination ranging from 0. 2 -0. 9 MBq per square metre. - Presence of Iodine-131 in milk samples, -Cesium-137 have been detected in leaf vegetables (spring onions and spinach), -distribution of food from the areas affected has been restricted.

Sheltering, evacuation of the population - the evacuation of the population from the 20 kilometre zone around Fukushima Daiichi has been successfully completed. Japanese authorities have also advised people living within 30 kilometres of the plant to remain inside. Administration of the iodine tablets - Recommandation for evacuees leaving the 20 kilometre area to ingest stable (not radioactive) iodine. The pills and syrup (for children) had been prepositioned at evacuation centers.