IVITMM r NATIONAL WORKSHOP ON RADIATION PROTECTION AND WASTE MANAGEMENT 17 - 21 MARCH, 1997 Organized By FEDERAL RADIATION PROTECTION SERVICE, IBADAN and NATIONAL AGENCY FOR FOOD AND DRUG ADMINISTRATION AND CONTROL (NAFDAC), ABUJA at the FEDERAL RADIATION PROTECTION SERVICE Department of Physics University of Ibadan, Nigeria TOPIC: BACKGROUND RADIATION AND MAN - MADE AND SOUCES OF RADIATION By Professor Ayo Babalola Federal Radiation Protection Service, Department of Physics, University of Ibadan, Nigeria 3 0-28 L 2. I. Introduction There is a history of up to 50 years of the development of man's use of the atom, and today this industry can be considered as matured technology. However the benefits that have resulted from the use of the atom are not without consequences which are of concern. For few topics have commanded as much attention from all quarters (scientists governments and the general public) as the management of the use of the atom. Ionizing radiation which results from the breaking of the atom is a form of energy, and on account of its ionisation effects, it constitutes hazard to all biological systems, hence the general concern. This concern is born-out of the fact that ionising radiation release (without control) is more potent than the hurricane or earthquake, whose passage is only known by the effects they leave behind. In our discussion of the sources of ionising radiation that are man made, we have to identify the human - needs that led to this peculiar venture which ironically is now viewed in same way as the opening of the pandora box. II. Human needs and Ionising Radiation Human needs continue to increase the use of many sources of ionising radiation. They turn out to be the most effective and reliable tool to solve specific human problems. In most, if not all these cases, the benefit derived outweighed either the level of damage, or the hazards involved in their applica­ tion. These will be summarised under four headlines. 1. Food and Agriculture The use of radiation (in form of control exposure to radioisotope and other nuclear techniques) has been to solve important agricultural problems which have defied known convectional methods. They are aimed to (i) produce high yielding, high - protein varieties of food crops. (ii) produce disease and weather - resistant crop vari 'lies (iii) make efficient use of water resources (iv) Determine fertilizer uptake efficiency and optimize nitrogen fixation. (v) Control or eliminate insect pests. 3. (vi) prevent losses of crops during storage (vii) improve productivity and health in domestic animals (viii) protect the agricultural environment and (ix) Extend the shelf-life of food through irradiation. The application of radioisotopes and radiation technique under strict regulation have proceed better than traditional methods. Nearly 1000 crops varieties derived from radiation induced mutations today are grown on several million hectares, yielding economic gains estimated in the billions of dollars. The use of radiation techniques in pest control has helped fight the lost of crops to insects and loss of livestock from diseases spread by insects. In most of these cases, the insects are sterilized by radiation in cases when the insects became resistant to chemical use or replace poisonous insecti­ cides which pollute the environment. 2. Industry Radioisotopes as tracers are used for many aspects of manufacturing. Radioisotope thickness gauges are used in the making of continuous sheets of materials (paper, plastic, film metal etc) when it is desirable to avoid contact between the gauge and material . Radiation processing, which involves the use of conven­ tionally produced X-rays, gamma-rays (Colbalt - 60) or high energy electrons, has grown at a steady rate of 10-15% per year. More than 135 industrial gamma irradiators and about 400 electron beam machines are operating in about 42 countries. The estimated total value of products processed using radiation is at more than two billion dollars. The radiation processed products include foodstuffs, hospital and medical supplies, various plastics, rubber products, and wire and cables. 3. Medicine and Health Care The impact of radiation X-rays and radioisotopes in medicine has grown rapidly. Screening, diagnosis , prognosis and therapy, to varying degrees, have benefitted from this development. More recently other important techniques such as nuclear magnetic resonance and the use of advanced X-ray technology in digital radiography involving computerised Tomography and Angiography have been introduced. In addition a field known as Nuclear Medicine now exists which includes 4. advanced techniques in nuclear cardiology. All these supplement the age-old isotopic methods which are still in use. For diagnostic purposes alone many million tests are made each year, such that a third of all hospitals patents benefit from the use of nuclear medicine. The use of radio­ isotopes in medical therapy are standard. Iodine is used in in the treatment of some types of thyroid cancers which cannot be moved by operation. Other cancers are often treated using gamma-rays from Cobalt - 60 sources, while sealed radioactive sources, such as radium - 226, irridum - 192, and cesrum - 137 and Cobalt-60 are used for brachyth. Sterilization of medical product such as surgical dressings, sutures, catheters and syringes are routine procedures. In summary an estimated 10,000 gamma-earneras-imaging instruments used in combination with radioisotopes in medical diagnosis are installed world-wide, supporting a range of nuclear medicine procedures. In many countries nuclear medicine has become routine in hospitals that up to one in every four patients use it. In the U.S. more than 10 million procedures are performed annually. Finally, we will like to identify the development of vaccines against parasitic infections affect more than 900 million people in the tropical zones. Nuclear techniques are for diagonosis of liver and thyroid diqeaseg, and human nutrition research of trace element deficiencies such as iodine deficiency- which in Asia alone affects more than 400 million people. The attendant problem will be examined later under waste disposal problems. 4. Energy - Environment and Research The energy production is perhaps tiu. most visible and controversial peaceful use of the atom. Nuclear power plants produced one-third or more of the total electricity in 11 3 countries in 1988 . Percentage of total electricity supplied by nuclear power ranged from 70% to 15% in 16 countries. There are 429 nuclear power reactors connected to electricity grids which accounted for 17% of the world's total electricity production. Less noticed in the energy field are other applications of nuclear energy in the oil and gas industries. Table 1 shows the national percentages of nuclear production for the year 1985-88 collected frpm IAEA sources^. 5. In operation are 326 nuclear research reactors used to support work in many science oriented disciplines. These are used in 55 industrialised and developing countries as a training tool, and produce radioisotopes used in industry, agriculture and medicine. Energy trends today are pointing towards an increase, in the installation of power reactors despite recent mounting campaigns. The issue of greenhouse effects arising from gases emitted from convecti'onal electricity plants has increased the environmental appeals to opt for cleaner power generators. In addition the comparative environmental costs of different energy sources has called for the use of nuclear power for electricity generation that do not emit carbon dioxide. The availability of fresh water has been national problems of many countries especially in sub-sahara Africa and Middle-East. Underground water reserves exist, but never reached the surface because not enough is known about their quantity, and development potential to make it economic to exploit them. Nuclear techniques using radioisotopes are precise modern tools for the study of water resources. They provide adequate information on the origin, distribution, age and properties of water in a given region. Human mining and milling of radioactive ores for various human needs:- example are to provide nuclear fuel - the raw materials - for nuclear power are Uranium and thorium; and in the mining for tin etc. highly radioactive waste materials like monazite and ziroon are stock piled in mining sites and 7 millings are tailing . There are records of wrong use and dispersal of these wastes which have become a major environ­ mental problem worldwide. Even the mining of gold and other unsuspected minerals add their little percentage of the environmental problems arising from human mining processes. This now brings us to the implications of the human uses of sources of ionising radiation. This is the issue of nuclear safety, and radioactive waste management; an issue which has beclouded man's successful uses of radioactive sources and nuclear energy for growth and development. Ill Nuclear Safety and Radioactive Waste Management There is a remarkable record of man's use of ionising radiation and the undisputable progressive contributions it has made to the development, survival and improved activities in all sectors over the past fifty years, However,few topics 6. have attracted world-wide discussion and critical review as nuclear safety and radioactive waste. In many countries today the future development of nuclear technology is dependent on acceptable solutions for nuclear waste management. The event at Chernobyl has