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

2. Forms of ionizing radiation
Particulate radiation
Electromagnetic 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
Directly ionizing
Neutron radiation
in which energy is carried by
oscillating electrical and magnetic fields travelling through space at speed of light

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

4. Fission

5. Nuclear reaction and energy production

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

7. Radiation accidents 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

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

9. Where do radiation accidents occur?
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

10. Scale of radiation accidents
Small scale radiation accidents
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
usually involve a large source term and many people irradiated/contaminated
require specialist treatment in both primary and secondary medical facilities
can lead to widespread public health action to mitigate the effects of contamination.

11. Industrial radiography
Inspection of products (non-destructive testing).
Gamma radiation sources (Ir-192 or Co-60) are used to inspect a variety of materials.
The vast majority of radiography concerns the testing and grading of welds on pressurized piping, pressure vessels, high-capacity storage containers, pipelines.
Another application of radioisotopes in the manufacturing process is called gamma-radiography.  This process uses gamma-ray radioisotopes to test materials for flaws such as invisible cracks, defects and occlusions in welds, etc.  The advantage of gamma radiography compared to non-nuclear technologies is that gamma radiography can be done thoroughly and non-invasively (one does not have to cut the material open), as well as more rapidly and cheaply.  It can even be done continuously as objects pass by on a conveyor belt. The process is very similar to x-ray radiography in a hospital or x-ray screening of luggage at an airport.  The difference is that instead of using x-rays, gamma radiography uses a source that is more penetrating, such as cobalt-60, and that is portable and easy to use.  X-ray sets can only be used when electric power is available and when the object to be x-rayed can be taken to the x-ray source and radiographed.  Radioisotopes have the supreme advantage in that they can be taken to the site when an examination is required, and no electric power is needed.  All that is needed to produce effective gamma rays is a small pellet of radioactive material in a sealed titanium capsule.  The capsule is placed on one side of the object being screened, and some photographic film is placed on the other side.  The gamma rays, like x-rays, pass through the object and create an image on the film.  Just as x-rays show a break in a bone, gamma rays show flaws in metal castings or welded joints.  The technique allows critical components to be inspected for internal defects without damage and in place. Because isotopes can be transported easily, gamma radiography is particularly useful in remote areas where, for example, it has been used to check welds in pipelines that carry natural gas or oil.  Where a weld has been made, special film is taped over the weld around the outside of the pipe.  A machine called a "pipe crawler" carries a shielded radioactive source down the inside of the pipe to the position of the weld.  There, the radioactive source is remotely exposed and a radiographic image of the weld is produced on the film.  This film is later developed and examined for signs of flaws in the weld.

12. Gamma radiography 1.5 TBq Ir-192 At 1 m. from the source:
In gamma radiography, the radiation comes from a radioactive source, such as Iridium-192, for example. The radioactive source is placed in a portable protective container during storage and transport, as shown in the picture. When in use, the source can be pushed forward to the radiating position with the help of a mechanical crank. After use, the source is then returned to its shielded position. Industrial radiography usually has to be carried out outdoors or within shielded enclosures, as shown in the figure. The surrounding area must then be cordoned off and the dose rate outside the barred area should not exceed 7.5 µSv/hour. The dose rate is controlled by the operators through the use of a hand monitor. In order to meet the barrier requirements, it is essential that the primary beam from the radioactive source or x-ray machine is shielded, because of the high radiation intensity in the beam. There will be radiation also in the area immediately outside the primary beam, and this is known as scattered radiation or secondary radiation. However, the intensity of this radiation is much lower, on the order of 1/1000 the intensity of the primary beam. A radioactive source can never be turned off; hence, upon the completion of exposure, the source must be redrawn into its shielded container. The operator must them check with the hand monitor that the source is safely back in its shielded position. An x-ray machine on the other hand ceases to emit radiation once the power has been shut off, and hence does not need any kind of protective shielding
1.5 TBq Ir-192
At 1 m. from the source:
150 mGy/h = 2.5 mGy/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

13. 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
Skin burn from radiation in many ways is similar to a sunburn

14. INES International Nuclear and Radiological Event Scale

15. Examples of events at nuclear facilities
7 Chernobyl, 1986 — Widespread health and Environmental effects. External release of a significant fraction of reactor core inventory.
6 Kyshtym, Russia, 1957 — Significant release of radioactive material to the environment from explosion of a high activity waste tank.
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.
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.

16. Examples of events involving Radiation Sources and Transport
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.
4 Fleurus, Belgium, 2006 — Severe health effects for a worker at a commercial irradiation facility as a result of high doses of radiation.
3 Yanango, Peru, 1999 — Incident with radiography source resulting in severe radiation burns.
Ikitelli, Turkey, 1999 — Loss of a highly radioactive Co-60 source.
2 USA , 2005 — Overexposure of a radiographer exceeding
the annual limit for radiation workers.
France, 1995 — Failure of access control systems at accelerator facility.
1 Theft of a moisture-density gauge.

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

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

19. Accident description

20. (caesium chloride) 50.9 TBq (1375 Ci)
Source
137CsCl
(caesium chloride) TBq (1375 Ci)
main gamma: 0.66 MeV
main beta: 1.17 MeV
T 1/2=30 years

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

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

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

24. Decontamination

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

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

27. Contamination sources in nuclear accidents

28. Inhalation
Soluble particles (3H, 32P, 137Cs) absorbed directly into circulatory system
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

29. Ingestion All swallowed radioactive material enters digestive tract
primarily from contaminated food and water
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%)

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

31. Chernobyl reactor accident
Total contaminated surface (> 1 Ci/km2): km2
Near zone (<100 km): deposition of heavy particles ( Sr, Pu...
Far zone (up to 2000 km) : deposition of volatile elements (I, Cs)

32. Radionuclides released

33. Main radionuclides contributing to health effects
iodine - 131
volatile
T1/2: 8 day
disappears from environment in 2 months
inhalation and ingestion
concentrates in thyroid
caesium - 137
volatile
T1/2: 30 years
stays long in environment
body elimination in about 100 days
homogenous distribution in all organs and soft tissues

34. Thyroid cancer and ionizing radiation
Chernobyl accident shows that exposure to iodine isotopes may cause increase in prevalence of thyroid carcinoma
In 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 (children <15 years old at diagnosis)

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

36. Chernobyl conclusions
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
BMT –very limited indication
Some radiation burns did not re-epithelialize, required surgery
Severe multiple necrotic-ulcerative radiation burns in Chernobyl fireman on Day 40 after the accident

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

38. 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.

39. A boiling water reactor (BWR) splits atoms to release nuclear energy
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.

40. 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.

41. To vent some steam outside this vessel in order to reduce the pressure
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.

43. 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 18th.
As another dramatic consequence of the earthquake, the storage pools which contain the spent fuel of reactors lost some of their water.
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.

44. Protective actions Radiation monitoring
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)

45. 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 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 km from the plant.
Available results show contamination ranging from 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.

46. 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.