SAFETY OF RADIATION SOURCES

To illustrate this challenge, let me begin by citing the US operational experi-ence with licensed nuclear power plants and radioactive sources. In the USA there are 103 licensed operating nuclear power plants. Resident inspectors are present at all of these sites, and their inspection activities are routinely supplemented by inspections performed by regional and headquarters offices. The worst US nuclear power plant accident, at Three Mile Island Unit 2, resulted in the release of radioactive materials to the environment. However, no member of the public was exposed to radiation even in excess of the radiation dose limits for members of the public in normal situations from this accident nor from accidents or routine operations at any other US licensed nuclear power plant. This statement, however, cannot be made with respect to US operational experience with licensed radioactive sources.

In comparison to the 103 licensed nuclear power plants, about 190 000 licensees use radioactive materials subject to the US Atomic Energy Act, as amended either in accordance with a specific licence or in the form of devices containing radioactive sources authorized by a general licence. Over two million devices containing radioactive sources have been distributed to US licensees. It is important to note that the US Nuclear Regulatory Commission (NRC) does not license all

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radioactive sources — radium sources being the predominant category of unlicensed sources — and does not regulate radioactive sources used by the US Department of Energy.

US operational experience with radioactive materials includes serious acci-dents, some of them resulting in radiation injuries and death and others in radioactive contamination. The major applications in which most major accidents have occurred are irradiation, industrial radiography, brachytherapy and teletherapy. Accidents with radiation sources are also a worldwide problem. During this Conference, we will learn more about some of these individual accidents and about IAEA summary reports on them.

Another area of concern is lost, stolen and abandoned radioactive sources. Each year, the NRC receives about 200 reports of lost, stolen or abandoned radioactive sources and devices. It is important to note that such reports are received only when licensees recall that they have a source, know that is lost or stolen, know that there is a requirement to report the loss or theft and make that report. Therefore, the volume of reports received probably represents but the tip of the iceberg. In some of these cases, the loss of control of radioactive sources has resulted in radiation overexpo-sures of unsuspecting members of the public or in radioactive contamination.

The US metal recycling industry has been particularly affected by losses and thefts of radioactive sources which subsequently became mixed with metal scrap des-tined for recycling. Since 1983, US steel mills accidentally melted radioactive sources on 20 occasions, and radioactive sources have been accidentally melted at other metal mills on 10 other occasions. While radiation exposures of mill workers and the public have, thus far, been low, the financial consequences have been large. US steel mills have incurred costs averaging US $8-10 million as a result of these events, and in one case the cost was US $23 million.

Lost, stolen and abandoned sources appearing in recycled metals also constitute a worldwide problem. Thirty other, similar events are reported to have occurred in at least 18 other countries (Table I [1]). Others may have occurred but have not come to our attention or cannot be confirmed. These events have the potential for international consequences as well, because of the transboundary transport of radioactive effluents from a mill that has accidentally melted a source, such as occurred recently in Spain, or as the result of international marketing of mill products and by-products that have become contaminated, such as ^Co contaminated steel products. Radioactively contaminated products imported into the USA have been found on ten occasions (Table II). The sources of contamination in most of these cases are probably radio-active sources that became mixed with the raw materials used to make the products.

Although none of these cases resulted in significant exposures of the public in the USA, another result of their unexpected appearance in the marketplace is to raise con-cerns about the effectiveness of regulatory programmes intended to ensure the safety of radiation sources.

TABLE I. MELTINGS OF RADIOACTIVE MATERIALS [1]

US Pipe & Foundry, AL Brazilb

KEYNOTE ADDRESS 23 US Pipe & Foundry, CA Bulgariab

a Multiple cases reported, earliest circa 1910.

b Contaminated product exported to USA.

c Contaminated vanadium slag exported to Austria; detected in Italy.

d Contaminated by-product (electric furnace dust) exported to USA.

To again cite from US experience, the NRC has a well developed regulatory programme for radioactive sources. Nonetheless, the data that have been collected on lost and stolen radioactive sources and on discoveries of uncontrolled sources in the public domain, such as in recycled metals, showed a clear need for modifications of that programme. In response, in 1998, the Commission directed that changes be made to provide more routine contacts with licensees using radioactive sources to remind them that they are responsible for the accounting, control and proper disposal of licensed material. The point of this example is that the Commission could not have

TABLE II. RADIOACTIVELY CONTAMINATED PRODUCTS IMPORTED INTO THE UNITED STATES OF AMERICA [2]

Item

justified making this decision — which has resource implications — without the collection and analysis of operational data to support it. Equally important is the need to share this kind of information.

The IAEA has taken a leadership role in this regard. For example, with respect to operational experience with radiation sources, the IAEA has prepared nine reports on individual accidents, six of them published, as well as reports on lessons learned from approximately 140 accidents that occurred in irradiation, industrial radiography and radiation therapy. The IAEA has assisted in national efforts to 'condition' unused, surplus radium sources to prevent their entering the public domain in an uncontrolled manner. In another initiative the IAEA is working with individual competent author-ities to strengthen national regulatory programmes to oversee the safety of radio-active sources.

When serious radiation accidents occur, the demands upon the responding national authorities can become overwhelming. In such cases, arrangements for interagency and intergovernmental assistance are essential. The IAEA has provided assistance in investigating and dealing with accidents involving radiation safety and security on ten occasions.

There are many lessons to be learned from these operational safety experiences.

The most important of these is the need for strong, effective national regulatory pro-grammes to oversee the use of radiation sources. This will be a recurrent theme in the papers to be presented this week. It is equally important that there be in place a pro-gramme to review and evaluate the effectiveness of regulatory propro-grammes and, when appropriate, the will and the flexibility to enact changes to improve the effectiveness

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of those programmes. Considering the rather large number of radiation sources in use worldwide, the safety record is reasonably good. When used properly by trained per-sonnel with effective regulatory oversight, radioactive sources are safe and their many uses provide a net benefit to society. It is only when proper procedures are not followed or when effective radiation control programmes are lacking or control of radiation sources is lost that our problems begin.

3. SECURITY AND ILLICIT TRAFFICKING OF