Summary

The National Academies of Sciences, Engineering, and Medicine (the National Academies) were tasked by Sandia National Laboratories with assessing the status of medical, research, sterilization, and other commercial applications of radioactive sources and alternative (nonradioisotopic) technologies in the United States and internationally. The purpose of the study was to support existing and future activities under the National Nuclear Security Administration Office of Radiological Security program to reduce the current use of high-risk radiological materials in these applications and promote alternative technologies. The study examined Category 1, 2, and 3 sources, which are the three most hazardous source categories in the five-category system developed by the International Atomic Energy Agency (IAEA). The system ranks the sources primarily in terms of their potential to cause deterministic¹ health effects to people handling or otherwise coming in contact with them if these sources are not safely managed or securely protected. National regulatory agencies, including the U.S. Nuclear Regulatory Commission (U.S. NRC) have adopted IAEA’s source categorization system to regulate the safety and security of radioactive sources.

The National Academies appointed an expert committee to carry out the study and prepare a technical report. This summary contains the complete list of the committee’s findings and recommendations, as listed below.

Finding 1: Radioactive sources continue to be used broadly, both nationally and internationally, for medical, research, sterilization, and other commercial applications. No new applications of high-risk (Category 1 and Category 2) and moderate-risk (Category 3) radioactive sources have emerged during the past 10–15 years. One application of Category 1 sources, the use of radioisotope thermoelectric generators for land-based power, has been phased out.

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¹ A deterministic effect is one for which a threshold level of dose exists, and above it, severity of the health effect increases as the dose increases.

Finding 2: The U.S. government and the international community have taken actions to strengthen the security and accountability of radioactive sources. These actions focus primarily on high-risk (Category 1 and Category 2) sources because of their higher potential to cause deterministic effects in persons handling or coming in contact with them. Security and accountability for Category 3 sources have a lower priority because of their lower potential to cause deterministic effects.

Finding 3: In the United States, Category 1 and Category 2 sources are tracked by the National Source Tracking System, a nonpublic centralized database maintained by the U.S. NRC since 2008. The number of Category 1 and Category 2 sources has increased over the past 12 years by about 30 percent.

Finding 4: The less stringent security measures and lack of national and international tracking of Category 3 sources make them vulnerable to unauthorized transactions and theft.

Finding 5: Recent modeling analyses of radiological events concluded that small radiation releases and small radiation exposures of populations below the levels that can cause deterministic effects may have serious and long-term socioeconomic consequences. Various real-life radiological events are supportive of this conclusion. A safety system that is based solely on deterministic effects of radioactive sources may provide an inadequate level of protection to society.

Recommendation A: The International Atomic Energy Agency, the U.S. Nuclear Regulatory Commission, and other organizations should consider reframing their source categorization schemes to account for both (a) probabilistic health impacts such as development of cancer later in life and (b) economic and social impacts. This reframing would lead to a more holistic description of overall risk, including potential consequences if the sources are not safely managed or securely protected.

Recommendation B: The International Atomic Energy Agency, the U.S. Nuclear Regulatory Commission, and other organizations should make changes to their security and source tracking guidance and regulations based on the outcome of the reframing in Recommendation A.

Recommendation C: In parallel, the U.S. Nuclear Regulatory Commission should phase in tracking of Category 3 sources in the existing National Source Tracking System. Such tracking would provide a more accurate accounting in the national inventory of Category 3 sources and would increase accountability for owning these sources and regulating their use. The U.S. government should make informed decisions about potential security enhancements for Category 3 sources at the facilities where these sources are located.

Finding 6: The U.S. government’s risk reduction goal of replacement of radioactive sources with nonradioisotopic alternatives will not be realized until disused sources are properly removed and disposed of. The high costs of disposal and the limited options, resources, and guidance for disposal domestically and internationally may be prohibitive both for adoption of alternatives and for appropriate end-of-life disposal of radioactive sources.

Recommendation D: The U.S. Nuclear Regulatory Commission should expand its current requirements for financial guarantees to ensure that they adequately cover the end-of-life management for newly licensed radioactive sources. The U.S. government should also develop and implement a national strategy for end-of-life management of currently owned and orphan Category 1 and Category 2 radioactive sources and should consider it for Category 3 sources.

Finding 7: Many national and international government and nongovernmental organizations have contributed to the increasing visibility of alternative technologies as a way to reduce security risks from radioactive sources. However, no organization is currently equipped to promote the broad range of alternative technologies and address adoption issues in a global context. Such an organization or network of organizations could unite technical, regulatory, financial, policy, and country-specific resource information to influence decisions about adopting alternative technologies and facilitate the transition to alternative technologies for medical, research, and commercial applications, where appropriate.

Finding 8: Progress with developing alternative technologies has been uneven across different applications and radionuclides (see Table S.1). Except for blood irradiation, where x-ray technology is considered equivalent to cesium-137 irradiation, and external beam therapy, where linear accelerator technology is considered superior to cobalt-60 teletherapy, there are no broadly accepted replacement technologies for other applications. In some applications, no suitable replacement technology has been developed.

As described in Finding 12, despite technological advancements for medical applications, challenges exist in adopting alternative technologies in low- and middle-income countries.

Finding 9: Several large companies are investing in research and development to provide solutions to specific challenges associated with adoption of alternative technologies. The transition of a creative idea to a commercial product, if successful, can take years (often more than a decade) and requires substantial investments.

Finding 10: Several smaller companies have alternative technology development projects under way with financial support from the Small Business Innovation Research and Small Business Technology Transfer programs administered by the National Nuclear Security Administration.

Recommendation E: The National Nuclear Security Administration should prioritize funding of research and development projects that aim to develop alternatives to use of radioactive sources in applications where there are currently no acceptable nonradioisotopic alternative technologies.

Finding 11: The most notable progress in adopting alternative technologies is the worldwide adoption of x-ray technologies for blood and research irradiation. In the United States, the financial incentives provided by the government through the Cesium Irradiator Replacement Project are a major contributor to the transition from cesium irradiators to x-ray technologies and the gradual phasing out of cesium-137 in the form of cesium chloride from medical and research applications. Additional progress could be made with replacement of cesium irradiators used in research by assisting the research community with designing and funding equivalency studies.

Recommendation F: The National Nuclear Security Administration should engage with federal partners such as the Department of Health and Human Services, the National Science Foundation, and the Food and Drug Administration to support equivalency studies for researchers who are considering replacing their cesium or cobalt research irradiators with alternative technologies. The findings of these studies should be made broadly available.

Finding 12: Alternative technologies do not provide a “one-size-fits-all solution,” and this is particularly evident in medical applications across high- and low- and middle-income countries because of the stark disparities in access to health care and resources. Adoption of alternative technologies for cancer therapy in some low- and middle-income countries has had unintended negative impacts on patient care because of lack of trained workforce, required resources, and infrastructure to make these alternatives viable options.

Recommendation G: Efforts by the U.S. government and other national and international organizations to reduce use of high-activity radioactive sources globally and in low- and middle-income countries should be driven by examination of the local resources, infrastructure, and needs. In situations in which local resources and infrastructure cannot support alternatives, efforts should focus on enhancing radiological security for existing radioactive sources, assisting with building the infrastructure, and supporting research and development projects to adjust the technologies to operate effectively in resource-constrained environments, for example, when there is unreliable electricity supply.

Finding 13: A progressive transition to alternative technologies is taking place in sterilization applications. Utilization of electron-beam (e-beam) technologies in medical device sterilization has increased during the past 10–15 years both domestically and internationally, and it is expected to continue to increase to meet growing demand for this application. Several companies have also announced plans to open new x-ray sterilization facilities. Alternative technologies for other sterilization applications, including food irradiation for safety and phytosanitary treatments and insect sterilization are also increasingly accepted as viable replacements for radioactive sources in many countries.

Finding 14: Little progress has been made domestically with adopting alternative technologies for some other commercial applications, particularly in some nondestructive testing applications and well logging. This is because there are currently no viable or cost-effective alternatives, the alternatives either compromise or do not offer enhancements in performance, or they produce data on material and structures that are not directly comparable to those produced by radioactive sources.

Recommendation H: The National Nuclear Security Administration should engage with other offices within the Department of Energy, the National Science Foundation, and professional societies to support equivalency studies for well logging and industrial radiography service providers that are considering replacing their radioactive sources and adopting an alternative technology. The findings of these studies should be made broadly available.

Finding 15: No progress has been made domestically and internationally with adopting alternative technologies for calibration systems to replace cesium-137 and cobalt-60 sources. No obvious nonradioisotope alternatives exist for replacing the cesium chloride sources used in these applications, and no research and development is currently dedicated to exploring alternatives. The lack of alternatives poses an obstacle in global efforts to eliminate cesium-137 in the form of cesium chloride.

Recommendation I: The National Institute of Standards and Technology should engage with the research community as well as federal, industry, and international partners to initiate research on alternatives to cesium chloride for calibration applications. This engagement should start immediately to prepare for the possible future elimination of the use of cesium-137 in the form of cesium chloride.

TABLE S.1 Progress in Adopting Alternative Technologies in Different Applications

NOTE: CIRP = Cesium Irradiator Replacement Project; e-beam = electron beam; EtO = ethylene oxide; HDR = high dose rate; keV = kiloelectron volts; linac = linear accelerator; LMIC = low- and middle-income country.

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