By George Lobsenz
A National Academy of Sciences (NAS) panel has urged the U.S. government to develop policies to phase out radioactive cesium chloride sources now widely used for medical purposes, saying they pose unacceptably high “dirty bomb” risks and can be replaced with devices posing less danger to the public.
The expert panel also said the Nuclear Regulatory Commission (NRC) and other federal agencies should consider policies to speed the replacement of other high-risk radioactive sources without unduly hampering the wide range of industries that depend on them to perform essential medical, safety and energy exploration functions that benefit all Americans.
In particular, the panel called for a “cautious” government effort to replace a relative handful of radioactive sources–those containing cesium-137, americium-241, cobalt-60 and iridium-192–that account for more than 99 percent of the security risks posed by terrorists intent on detonating an explosive device designed to spew long-lasting radioactivity in U.S. cities.
The NAS study also suggested the NRC’s regulatory approach on radiation sources has been too narrowly focused on preventing deaths or serious exposures caused by a dirty bomb. It said NRC had to recalibrate its policies to also prevent the broader economic and social disruption that would result from a successful dirty bomb attack that effectively forced authorities to cordon off large contaminated areas in a city.
“A radiological incident (an accident or especially an attack) could have its most long-lasting and far-reaching effects as a result of contamination of land, buildings and infrastructure in densely populated regions, partially or completely disabling those assets for human use for long periods of time,” said the Committee on Radiation Source Use and Replacement of the NAS’ National Research Council. “The economic and social disruption caused by such incidents can be difficult to quantify, but they are critical to understanding the scope of the impact beyond the fatalities and severe bodily injuries caused by these events.
“Having taken an essential first step in considering…health effects from possible radiation exposure from an incident involving radiation sources, the U.S. NRC should now include economic and social disruption in its risk analyses of radiation sources.”
In response to those recommendations, NRC said it and other federal agencies already were reviewing many of the issues raised by the NAS study–including the replacement of cesium chloride–through an interagency task force on dirty bombs created by the Energy Policy Act of 2005 (EPACT).
NRC officials also said they had significantly strengthened security requirements for radioactive sources since the September 2001 terrorist attacks in New York and Washington, and they warned that the nation needed to move carefully in replacing sources that provide major societal benefits.
The NAS report touches on a sensitive area for NRC because the agency has been the focus of harsh criticism in recent years for alleged lapses in its regulation of radiation sources. In particular, the Government Accountability Office, the auditing arm of Congress, recently set up a bogus business that succeeded in getting an NRC license for radioactive sources, though the license only covered “Category 3” nuclear materials, which are much harder to fashion into effective dirty bombs than high-risk Category 1 and 2 sources.
Congressional concern about radiation sources led to provisions in EPACT ordering the NAS to evaluate dirty bomb risks facing the nation and make recommendation on additional security measures.
The NAS panel looked at threats posed by the approximately 5,000 devices containing 55,000 high-activity radiation sources currently licensed by the NRC or state authorities for such uses as cancer therapy, food safety, sterilization of medical instruments, irradiation of blood for transplant patients, safety assessments of buildings, bridges and industrial equipment and exploration of geologic formations to find oil and natural gas deposits.
Of all those devices, the NAS panel said some 1,300 devices containing cesium chloride in powder form clearly posed the most serious risks because they were used in hospitals and medical centers in virtually every U.S. city, and their high levels of long-lasting radiation could be easily spread in air and water with a dirty bomb.
“Because of its dispersibility, solubility, penetrating radiation, source activity and presence across the United States in facilities such as hospitals, blood banks and universities, many of which are located in large population centers, radioactive cesium chloride is a greater concern than other Category 1 and 2 sources for some attack scenarios,” the study said.
“This concern is exacerbated by the lack of an avenue for permanent disposal of high-activity cesium radiation sources, which can result in disused cesium sources sitting in licensees’ storage facilities. As such, these sources pose unique risks.”
The NAS panel acknowledged that developing replacement devices for high-risk radiation sources would impose higher costs on many industries and that some new devices might not perform as well as those they replaced.
However, the study added: “Non-radioactive replacements exist for nearly all applications of Category 1 and 2 radionuclide sources (not just radioactive cesium chloride). At this time, these replacements may not be as practical or economically attractive, but most of them are improving.”
The NAS study examined a range of possible government policies to require or encourage industry to replace cesium chloride and other high-risk radiation sources, saying action was needed to spur replacement.
A key problem at present, the study says, is that industries using cesium and americium-241 sources are not responsible for all costs of using them. For example, companies are not required to get insurance to cover accident risks, and disposal is handled essentially free of charge by the Energy Department’s National Nuclear Security Administration (NNSA), DoE’s semi-autonomous nuclear weapons agency, because NNSA has the only available disposal facilities for high-risk sources.
As for its recommendations for near-term steps by policymakers, the NAS panel said: “Beyond a reconsideration of security requirements by the U.S. NRC using a more comprehensive set of potential consequences, the committee views a ban on new licenses for cesium chloride irradiators as the policy most worthy of immediate consideration by policymakers.
The committee also sees enabling the [NNSA] to recover cesium chloride irradiators more quickly as worthy of immediate consideration (as long as the old devices are not replaced with cesium chloride irradiators and the recovered devices and sources are not recycled). Buying back irradiators at a positive price to speed their replacement with alternative sources should also be considered, especially if supported by a more comprehensive assessment of risks by the U.S. NRC.
“Requiring that Category 1 and 2 source users establish decommissioning funds that reflect the full social costs of disposal should be considered as part of a long-term strategy for reducing the uses of radiation sources that involve net social costs.”