Ю. Посудін. Моніторинг довкілля з основами метрології

Лекція 16 aРАДІОЕКОЛОГІЧНИЙ МОНІТОРИНГ

Yuriy PosudinEnvironmental Monitoring with Fundamentals of

MetrologyLecture 16a

RADIOECOLOGICAL MONITORING

IONIZING RADIATION

• Radiation of sufficiently high energy to cause ionization in the medium through which it passes. • It may consist of a stream of high-energy particles (e.g. electrons, protons, alpha-particles) or short-wavelength electromagnetic radiation (ultraviolet, X-rays, gamma-rays).

CLASSIFICATION OF IONIZING RADIATION

• Alpha (α) radiation consists of a fast moving Helium nuclei and is stopped by a sheet of paper.

• Beta (β) radiation, consisting of are high-energy, high-speed electrons or positrons, is halted by an aluminium plate.

• Gamma (γ) radiation, turned

out to be the electromagnetic radiation having the wavelength shorter than 10-11 metres, is eventually absorbed as it penetrates a dense material.

Radiation Dosimetry

• Radiation dosimetry is the calculation of the absorbed dose in matter and tissue resulting from the exposure to indirectly and directly ionizing radiation.

Exposure Dose

• A measurement of radiation, at a given point, in relation to its ability to produce ionization. The unit of measurement of the exposure dose is the roentgen.

• Roentgen unit of X-radiation or gamma-radiation, the amount that will produce, under normal conditions of pressure, temperature, and humidity, in

1 kg of air, an amount Q of positive or negative ionization equal to 2.58 × 10−4 coulomb

X = dQ/dm[C/kg]

1 Roentgen = 2.58×10−4 C/kg

Absorbed Dose

Absorbed dose is a measure of the energy deposited in a medium by ionizing radiation. It is equal to the energy deposited per unit mass of medium, and so has the unit J/kg, which is given the special name Gray (Gy).

DA = dE/dm

The unit of dose is the gray (Gy) where

1 Gy = 1 J/kg

of tissue

1 rad = 0.01 Gy (rad – “Radiation Absoirbed Dose”)

dE

dm

Equivalent Dose

• Equivalent dose relates the absorbed dose in human tissue to the effective biological damage of the radiation. Not all radiation has the same biological effect, even for the same amount of absorbed dose. Equivalent dose is measured in an SI unit called the Sievert (Sv).

The Dose Equivalent The dose equivalent is determined as:

Н = DAWR WT,

• where DA is the absorbed dose; WR radiation weighting factor; WT tissue weighting factor .

• For x-rays and gamma rays and electrons absorbed by human tissue, WR is 1; WR is 10 for neutrons; for alpha particles it is 20.

• For bones, lung, stomach WT = 0.12; brain, kidney – 0.05; skin – 0.01.

The Dose Equivalent

The unit of dose equivalent is called the Sievert (Sv):

1 Sv = 1 J/kg tissue × constant

1 rem = 0.01 Sv

(rem – “Radiation Equivalent in Man”)

Radioactivity

Radioactivity - the radiation, including alpha particles, nucleons, electrons, and gamma rays, emitted by a radioactive substance.

Units of Radioactivity

• The becquerel (symbol Bq) is the SI derived unit of radioactivity.

• One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second.

1 Bq = s-1.

• The Bq unit is therefore equivalent to a decay rate of s−1.• The curie (symbol Ci) is a unit of radioactivity, defined

as

1 Ci = 3.7×1010 Bq

MEASUREMENT OF IONIZING RADIATION

СРП-68-01

Gas-Filled Detectors• The central electrode, or anode, collects negative charges. The

anode is insulated from the chamber walls and the cathode, which collects positive charges. A voltage is applied to the anode and the chamber walls.

• As a charged particle passes through the gas-filled chamber, it ionizes some of the gas (air) along its path of travel.The positive anode attracts the electrons, or negative particles. The detector wall, or cathode, attracts the positive charges.

• The collection of these charges reduces the voltage across the capacitor, causing a pulse across the resistor that is recorded by an electronic circuit. The voltage applied to the anode and cathode determines the electric field and its strength.

Gas-Filled Detectors

Ionizing Chamber

Geiger Counter Proportional

Counter

Voltage, V

Number of ions

Geiger-Muller Counter

Geiger-Muller Counter

Scintillation detector

• Scintillators are usually solids that give off light when radiation interacts with them.

• The light is converted to electrical pulses that are processed by electronics and computers.

• Examples are sodium iodide (NaI) and bismuth germanate (BGO).

• These materials are used for radiation monitoring, in research, and in medical imaging equipment.

Scintillation Counter

Scintillation Counter

Radioecological Monitoring

This is complex informational and technical system of observation, investigation, estimation and forecasting of radiation state of biosphere, territories near nuclear stations, that were suffered from radiating incidents.

ENVIRONMENTAL RADIOACTIVITY FROM NATURAL SOURCES

• Background radiation is constantly present in the environment and is emitted from a variety of natural and artificial sources. Primary contributions come from:

• Sources in the Earth: Soils and Rock, Building materials;

• Sources from space, in the form of cosmic rays; • The radon gas that is released from the Earth's

crust.

Natural Radioactivity in Ukraine

Ukrainian Crystalline ShieldIt occupies about It occupies about 39,6% 39,6% of all territoryof all territory

Uranium Mines in Ukraine

http://www.reachingcriticalwill.org/about/pubs/Inventory/Ukraine.pdf

Radon is produced from decay of radium-226 in the ground, and seeps into the underfloor region of a house

The fan draws the radon out from the underfloor region, and allows it to pass harmlessly into outside air

Without the fan, radon enters the home through the floorboards and enters the indoor air.

The radon in indoor air decays to heavymetals lead and bismuth, which attach themselves to dust particles in air and are retained in the lungs, when breathed in.

RadonUkraine has high level of irradiation by radon – up to 3.8 mSv/year

Natural Background Radiation

• A number of radioactive materials occur naturally in the earth itself. These radioactive materials all have very long half lives, and have been present in the earth since its creation.

• It is considered that background radiation is not dangerous for people because of their adaptation during long period of time.

Background Radiation in Kiev

• According to the data of observation posts, which are situated in Kiev, gamma background in 2002 was within 9-16 microR/h and made on the average 12 microR/h.

Man-made Background Radiation

This is the radiation which is emitted from isotopes that have escaped into surroundings from:

• nuclear tests;

• industrial uses of atomic energy;

• accidents (Chernobyl).

ENVIRONMENTAL RADIOACTIVITY FROM MILITARY SOURCES

• During the final stages of World War II in 1945, the United States conducted two atomic bombings against Japan in the cities of Hiroshima and Nagasaki.

ENVIRONMENTAL RADIOACTIVITY FROM MILITARY SOURCES

• Within the first two to four months of the bombings, the acute effects killed 90,000–166,000 people in Hiroshima and 60,000–80,000 in Nagasaki.

Nuclear Tests

• The nuclear powers have conducted at least 2,000 nuclear test explosions (numbers are approximated, as some test results have been disputed).

Japan Sea Contamination http://www1.american.edu/TED/japansea.htm

• The former Soviet Union and Russia had dumped radioactive waste on many occasions in the Far East water area including the Sea of Japan since 1950s.

• Soviet Union/Russia had several dump sites in the Sea of Japan and the North Pacific Ocean off Kamchatka peninsula.

• In the face of strong resentment in Japan, the United States and other countries, the Russian government reluctantly announced that it would suspend the dumping.

Radioactive contamination

• Radioactive contamination, is the uncontrolled distribution of radioactive material in a given environment.

• Most anthropogenic radionuclides are short-lived, but some have half-lives of many years:

137Cs - 30 years;

90Sr - 28.1 years.

Nuclear Tests

• United States: 1,054 tests • Soviet Union: 715 tests • France: 210 tests • United Kingdom: 45 tests • China: 45 tests • India: 6 underground tests • Pakistan: 6 underground tests • North Korea: 2 tests

Atomic tests reached a peak in the early 1060s

Nuclear test by the United States at

Bikini Atoll in 1946

Nuclear Weapon in Ukraine

Upon the breakup of the Soviet Union, Ukraine inherited a considerable nuclear potential, in the form of 176 SS-19 and SS-24 intercontinental ballistic missiles (ICBMs; 1,240 warheads) and 44 strategic bombers.

Nuclear Weapon in Ukraine

• Following the collapse of the Soviet Union, Ukraine inherited a sizeable nuclear weapons infrastructure.

• Ukraine's sudden possession of the third largest nuclear arsenal in the world left the newly independent country with a strategic decision of whether or not to return these weapons to Russia or be considered a nuclear weapons state.

• In the end, Ukraine decided to return the weapons to Russia and to join the Nuclear Nonproliferation Treaty as non-nuclear weapons state

ENVIRONMENTAL RADIOACTIVITY FROM INDUSTRIAL SOURCES

• Radioactive waste is a waste product containing radioactive material.

• The uranium is fabricated ino fuel rods which are inserted into the nuclear reactor.

Radioactive waste

Once the fuel rods are removed from the reactor, they must be cooled at least for the first year or two in a spent-fuel storage bay.

Nuclear Power in Ukraine

• Ukraine is heavily dependent on nuclear energy - it has 15 reactors generating about half of its electricity.

• In terms of nuclear energy Ukraine occupies 8 place in the world and 5 – in Europe.

Nuclear Power in Ukraine

Rivne

Khmelnitsky

South Ukraine

Zaporizhzhia

Chernobyl

Radioactive waste

• Ukraine previously sent its spent fuel to Russia to be reprocessed, but this course became a contentious issue after Russia passed a law in 1992 prohibiting the import of radioactive material into Russia.

• This action resulted in storage crisis at Ukrainian power plants. In 6/93, however, Russia passed a new law that allows Ukrainian spent fuel to be reprocessed, but not stored, in Russia.

Radioactive Waste in Ukraine• Over the territory of Ukraine are

situated over 8 thousand different institutions and organisations whose operation generates radioactive waste:

• 1. NPPs;

• 2. Uranium mining and uranium processing industry – about 65.5 millions tons of radioactive wastes are accumulated in Ukraine;

• 3. Medical, scientific, industrial and other institutions and organisations;

• 4. Chornobyl NPP excluded zone – more than 1.1 billions m3 of radioactive wastes are accunulated.

SURFACE CONTAMINATION

• Surface contamination is usually expressed in units of radioactivity per unit of area.

Ci/km2 and kBq/km2.

Disposal of hazardous object Disposal of hazardous object in Ukrainein Ukraine

Distribution of exposure dose power in Distribution of exposure dose power in Ukraine 1993Ukraine 1993

Distribution of exposure dose power in Distribution of exposure dose power in Ukraine 2002Ukraine 2002

Distribution of exposure dose power in Distribution of exposure dose power in Ukraine 2008Ukraine 2008

Radiation Contamination of Territory of Ukraine

http://www.rri.kyoto-u.ac.jp/NSRG/reports/kr21/kr21pdf/Nasvit1.pdf

Contamination of Foods

• In many European countries levels of I-131, Cs-134/137, Sr-90, and other radionuclides in milk, dairy products, vegetables, grains, meat, and fish increased drastically (sometimes as much as 1,000-fold) immediately after the catastrophe.

• As of 2000, up to 90% of the wild berries and mushrooms exceeded permissible levels of Cs-137 in Rovno and Zhytomir provinces, Ukraine.

Standards of Radionuclides in FoodsЗначення допустимих рівнів вмісту радіонуклідів (Бк/кг, Бк/л)

(Горбунов та інш., 2005) № з/п

Назва продукту Cs-137 Sr-90

1. Хліб, хлібопродукти 20 5 2. Картопля 60 20 3. Овочі (листові, коренеплоди) 40 20 4. Фрукти 70 10 5. М'ясо і м'ясні продукти 200 20 6. Риба і рибні продукти 150 35 7. Молоко і молочні продукти 100 20 8. Яйця (шт.) 6 2 9. Вода питна 2 2 10. Молоко згущене і концентроване 300 60 11. Свіжі дикі ягоди і гриби 500 50 12. Сушені дикі ягоди і гриби 2500 250 13. Лікарські рослини 600 200 14. Інші продукти 600 200 15. Продукти дитячого харчування 40 5

MUSHROOMS

• Many people enjoy wild mushrooms as a tasty contribution to their menu.

• But even more than two decades after the reactor accident of Chernobyl, the Federal Office for Radiation Protection measures enhanced activities of the radionuclide Cs-137 in some mushroom species.

FISH

• Several species of fish (bottom fish) are able to accumulate radionuclides from sediments.

UTILIZATION OF RADIOACTIVE WASTES

• About 1.7 millions m3 of liquid radioactive waste are created during one year in NPP.

UTILIZATION OF RADIOACTIVE WASTES

• The main approaches to managing radioactive waste to date have been segregation and storage for short-lived wastes, near-surface disposal for low wastes, and deep and secure burial for the long-lived high-level wastes.

UTILIZATION OF RADIOACTIVE WASTES

UTILIZATION OF RADIOACTIVE WASTES Yucca Mountain, Nevada

Yucca Mountain, Nevada 457 м

457 m

457 м

Radioactive waste in USA

Alternative Methods of Utilization

Space disposal

• Space disposal is an attractive notion because it permanently removes nuclear waste from the environment.

• However, it has significant disadvantages, not least of which is the potential for catastrophic failure of a launch vehicle.

• Furthermore, the high number of launches that would be required makes the proposal impractical (for both economic and risk-based reasons).

The system of early prevention GAMMA 1

The system of early prevention about radioactive accident GAMMA 1 was created in Ukraine in 1994-1998. It includes two subsystems of radiation monitoring, information and analytical centers, and system of communication which are located in Kharkiv.

RADIATION AND NUCLEAR EMERGENCY INFORMATION

• The RODOS (Real-time On-line Decision Support) system for off-site emergency management.

• As a result of these collaborative actions, a comprehensive decision support system (RODOS) has been developed which can be applied within Europe

RODOS (Real-time On-line Decision Support)system

European decision support systems (RODOS)

Невирішеність питань ліквідації наслідків аварії, у тому числі безпосередньо на ЧАЕС, недієвість економічних важелів у підтримці належних рівнів радіаційної безпеки на неядерних підприємствах, недостатність фінансування протирадіаційних заходів, недосконалість ядерного законодавства в частині фінансового забезпечення національних програм поводження з радіоактивними відходами, відпрацьованим ядерним паливом, зняттям ядерних об'єктів з експлуатації посилюють негативне ставлення населення до радіації взагалі та атомної енергетики зокрема. В державі виникла нагальна потреба значних обсягів коштів та матеріальних ресурсів для приведення стану радіаційної безпеки і захисту персоналу, населення й навколишнього середовища у відповідність до вимог національного законодавства (Україна. Радіаційна безпека. Всеукраїнська Екологічна Ліга, 2004).

Radiation - in every house• Information was published in No122 (1220) "Po-Kievski

Newspaper" 2008, May, 31th.

• On these days special services of the country declared about exposure of the whole criminal group, which organized large-scale "business" on export from the "zone" of everything, for that it’s possible to gain money.

• During the last sortie thieves took out the steel pipes taken from a burial on utilization of wastes contaminated by radiation.

• When dosimeter was brought to a body of the car - the radiation background was in 30 times above normal.

• Arrested persons have already confessed that they took out not only pipes, but also parts of cars, wood and even the caught fish.

• It is hardly to believe, but thieves even tried to take out the whole helicopter of Mi-8 (!) from Chernobyl in order to resell it then, under arrangement of original cafe.

• Punishment – up to three years of prison.