The Nuclear Regulatory Commission hosted an open public meeting Sept. 29-30, 2008 to discuss the security and continued use of cesium-137 chloride sources.
The workshop opened with remarks from Peter B. Lyons, commissioner of the NRC. He presented his views on the safety and security of sealed cesium-137 sources, which has been — and continues to be — a top priority for the NRC. Lyons reiterated that NRC has not made any decisions regarding the suspension of licensing of new cesium-137 chloride sources and emphasized that the information gathered at the meeting would be combined with other studies and vetted with the Interagency Radiation Source Protection and Security Task Force. The commissioner noted that the NRC and its federal partners need input on the potential impacts of actions and the range of alternatives that could potentially address issues associated with the removal or increased controls of cesium chloride sources. In addition, views on economic and societal costs associated with replacing these sources or how research would be impacted if they were not available need to be presented.
Cesium has a half-life in excess of 30 years. The focus on cesium is due to its chemical formulation, reactivity and widespread use in nonsecured locations. Specifically, it is largely distributed as a water soluble, chemically reactive salt used in numerous applications, including blood irradiation. Currently, all cesium chloride used in the U.S. comes from a single source in Russia. It is produced in the form of a highly dispersible radioactive salt that can be compressed and loaded into cylinders, often referred to as “pencils.”
Prior to panel discussions by users and experts in the applications of cesium chloride irradiation, a historical perspective of events that led to the heightened security awareness was presented. The impact of dispersion of this radioactive source material has been demonstrated in several incidents in the 1980s. The nuclear reactor explosion in Chernobyl left that region contaminated in large part due to the cesium present at the site, as it is impossible to decontaminate such a large and extensive area when the source of contamination is so dispersible. The immediate area around Chernobyl will be off-limits for more than a century. An incident in Goiania, Brazil, involved a decommissioned, self-standing irradiation device with a cesium source that was sold to a salvage yard. Individuals trying to scavenge the metal pierced the source. Seeing the blue glow, they removed the radioactive source and distributed it to friends and family. The material eventually was spread over a 1 square kilometer area and required the removal of more than 70 tons of dirt to minimize community exposure. In contrast, a similar incident with a cobalt source in Ciudad Juarez, Mexico, yielded a relatively controlled clean-up of pellets that had been released from a source broken into by salvage yard scavengers. Neither the Brazil nor Mexico case involved a large number of casualties as a direct result of radiation poisoning, but both required authorities to deal with the rapid dissemination of the radioactive sources, causing significant economic disruption.
After the terrorist attacks in 2001, safety and security requirements in the U.S. were enhanced through the use of increased security controls. Concerns about safety and security of radiation sources and devices have grown partly in response to fears that radiation sources could be used to make radiological dispersal devices, more commonly known as “dirty bombs.” The NRC issued requirements for increased controls (fingerprinting, and trustworthy and reliability verification) related to access to cesium chloride blood irradiators. In addition, the U.S. Congress directed the NRC to take several actions through the Energy Policy Act of 2005. One such action item called for the National Academy of Sciences to undertake a study identifying the uses of high-risk radiation sources and exploring the feasibility of replacing them with lower-risk alternatives.
In a 2008 report, the National Academy of Sciences recommended stopping the licensing of new cesium-137 chloride irradiator sources, prohibiting the export of such sources, providing incentives for decommissioning of existing sources, and replacing existing sources with possibly a less dispersible form of radioactive cesium, cobalt-60 or nonradioactive alternatives. While the report clearly recognizes the prolonged period needed to change technologies, it did not address all possible uses nor was it able to address all costs of conversion.
After the report was issued, several members of Congress proposed legislation promoting a more rapid conversion. Recognizing the need for data to support recommendations that would be sent back to Congress detailing what conversions and timelines were feasible, the NRC organized this public meeting of cesium chloride users to solicit input to a series of formal questions.
An account of the four major issues addressed at the meeting — 1) alternatives to the use of CsCl sources in compressed powder form; 2) use of alternative technologies; 3) possible phaseout of CsCl sources; and 4) additional requirements for enhanced security of CsCl sources — is detailed below. In addition, highlights of an AABB survey of non-blood center users of blood irradiation are included at the end of this document.
Issue 1 – Alternatives to the Use of CsCl Sources in Compressed Powder Form
The technology to manufacture a nondispersible form of cesium exists, but the activity of the source would be approximately half of the current cesium chloride. This could equate to blood products requiring twice the exposure time or re-engineering of the free-standing irradiators to hold double the number of sources. The only manufacturer of cesium sources is Mayak of Russia. It is estimated that an economic and feasibility study for producing cesium in a nondispersable glass or ceramic formulation would take at least one year, and if a specific path forward can be identified and agreed upon, it may take perhaps another three to five years for retooling the production lines or building a new facility. Furthermore, if the facility did make these investments, it was implied that there may need to be some type of economic agreement providing assurance of a market for the remanufactured source materials.
Blood organization representatives stated that prohibition or elimination of cesium chloride irradiators could result in a decrease in the standard of medical care if alternatives were not readily available. Additionally, limiting source material would have a significant impact on research, and any transition to another technology would have severe impacts on the medical industry. As with any change, there are specific issues to be resolved with replacement technologies. While there may be alternatives for certain applications, such as blood irradiation using X-rays, these alternatives are not considered to be suitable for many research applications, and any change in protocols would have to be revalidated. Given the numerous types of research performed today, there does not appear to be a “one-size-fits-all approach” to addressing these issues.
The blood organizations also emphasized that there needs to be a requirement for considering risk-benefit and cost-benefit in the decision-making processes and to balance the scientific facts and economic issues as well. Several factors that must be considered in any decision are the costs of alternatives, including replacement, installation, downtime, calibration and maintenance.
While replacement of cesium-137 irradiators with cobalt-60 as an alternative radionuclide source is an option, it has two very significant drawbacks: 1) the need to change the source more frequently (every five-10 years versus 25-30 years for cesium-137); and 2) the sheer weight of the device (due to the corresponding requirement to increase shielding for the source). The need to replace the cobalt-60 source more frequently than cesium-137 raised concerns regarding transportation. With 99 percent of transport containers no longer approved for use with irradiation sources, it greatly limits the number of devices that can be changed out during a finite period of time. In addition, the increased possibility for transportation or reloading accidents, and issues with disposal of cesium in general, become heightened since there is no current disposal pathway for these sources. To compensate for the much shorter half-life of cobalt-60, self-standing irradiators must have a much larger initial load, thereby mandating higher shielding requirements. Both of these factors greatly increase the weight of the irradiator. This often means that such devices need to be on ground floor or basement levels due to structural requirements. It also can make it impossible to replace a device on a higher floor because an elevator may not be rated to support that weight.
Issue 2 – Use of Alternative Technologies
The Advisory Committee on the Medical Uses of Isotopes presented information that the cost of a new X-ray device is approximately $250,000 with an annual maintenance contract costing about $33,000. However, the relatively low annual maintenance cost does not include the cost to replace the X-ray tube or power source, which requires replacement approximately every two years, depending on usage, at a cost of more than $50,000. This information is consistent with the results of an AABB survey in which 80 percent reported an annual maintenance contract cost of less than $25,000. Similarly, the AABB survey found that 85 percent of the annual maintenance contracts did not include the replacement of the X-ray tube or power source, which has an average cost of $40,000. To avoid downtime, a facility must schedule replacement of the X-ray tube before the end of its life expectancy.
Several of the organizations represented at the workshop expressed concern over the reliability of the current X-ray technology that is available. It was suggested that improved nonradioisotope devices (i.e., X-ray) with good reliability are at least three to four years away. The Department of Agriculture shared its experience with the devices, which demonstrated that they were not as reliable as the cesium chloride source irradiators. The agency purchased three X-ray devices and ultimately ended up purchasing a cobalt-60 device due to the excessive downtime of the X-ray devices. The devices also were in remote locations, making service issues particularly problematic. While linear accelerators have been used in the past, the potential to interrupt patient care, requirements for 24-hour availability, and challenges in dosimetry and quality control all make them an unattractive substitute for large-scale applications.
Issue 3 – Possible Phaseout of CsCl Sources
There was significant discussion about the impact on the medical and research communities of discontinuing the use of cesium chloride source irradiators. Inadequate availability of irradiation capability in hospitals and blood centers would have a dramatic impact on the standard of care that is provided to the most seriously ill patients. Specific medical concerns were raised at the meeting about ensuring the availability of irradiated blood for immunocompromised patients; maintaining the effectiveness of any new technology to prevent transfusion-associated graft-versus-host disease; ensuring easy access to free-standing devices within centers of care as opposed to geographically centralized irradiation facilities so that neonates can be transfused as soon as possible, minimizing any increase in the potassium level of the blood unit that comes after irradiation; and having the capability to irradiate blood products promptly.
In addition to the medical concerns, the phaseout of cesium chloride sources would negatively impact research efforts. Some historical research would have to be repeated due to the properties of the alternate technologies on the research materials. This would present an enormous cost to the research community. However, as of now, there is no alternative to the cesium chloride source for many research applications.
Concerns over the possible phaseout of cesium chloride sources were raised for all industries represented at the meeting. A recurring concern addressed reimbursement for the conversion to an alternative technology. Most hospitals and blood centers are not-for-profit entities and do not have a mechanism to receive specific reimbursement for the additional costs associated with converting to a new technology (i.e., equipment purchase, installation, decommissioning of old cesium irradiators, training, facility modifications). It was proposed that the government provide reimbursement and incentives to facilities to encourage conversion.
However, the rate at which conversion to an alternative technology could occur is limited by the ability to decommission the existing cesium chloride source irradiators. Decommission is a misnomer because there is no disposal area for the source material, only a limited number of long-term storage facilities. The federal government recently closed one of the few areas that agreed to store decommissioned radionuclides of this magnitude. Two of the largest manufacturers of irradiators commented that they have a limited capacity (i.e., small number of trained staff, only a few approved trucks, very limited number of shipping containers and storage facilities) for decommissioning irradiators. This limited capacity equates to the impracticability of replacing the current inventory in use (approximately 700) in a short time period. A blood center in New York detailed its costs for a recent decommissioning of a cesium-137 irradiator, which included $35,000 for the pickup and $70,000 to rent the shipping container, for a total of more than $105,000. Further limiting the potential rate for decommissioning is the lack of approved shipping containers. Specifically, as of Oct. 1, 2008, 99 percent of the approved shipping containers were retired. This will result in far fewer cesium source shipping containers available, potentially increasing the cost of decommissioning a device to as high as $1 million, according to one manufacturer.
Historically, an alternative to incurring the cost for decommissioning an irradiator is to register with the Off-Site Source Recovery Project (OSRP) — an option that was discussed at the meeting. OSRP is a U.S. government activity sponsored by the National Nuclear Security Administration's (NNSA) Office of Global Threat Reduction and is managed at Los Alamos National Laboratory through the Nuclear Nonproliferation Division. OSRP has an NNSA-sponsored mission to remove excess, unwanted, abandoned or orphan radioactive sealed sources that pose a potential risk to health, safety, and national security.
Since there are few acceptable alternative technologies except for X-rays used to irradiate blood, one of the suggestions made at the meeting was to provide incentives to manufacturers for research and development. Until this can be achieved, implementation of increased security measures would reduce homeland security risks.
Issue 4 – Additional Requirements for Enhanced Security of CsCl Sources
It was noted during the workshop that the NRC has mandated increased security measures to reduce homeland security risk. The increased security measures include, but are not limited to, performing a trustworthy and reliability review and fingerprinting for unescorted access to secure areas. In addition, information technology personnel must undergo the same security measures because they are the staff that controls access to secure areas. The NRC has been collaborating with several manufacturers on hardening efforts that would increase the amount of time for unauthorized access to the source material; a pilot program to achieve a goal of greater than 60 minutes is currently under way. A representative from FDA/CDRH indicated that the proposed device hardening efforts would not impact the device’s 510(k) status.
Many in attendance agreed that the increased security measures and the proposed hardening efforts would reduce homeland security risk. The scenario of requiring the decommissioning of all cesium chloride sources (no true disposal of source — only long-term storage) might create an unintended consequence of a greater risk. There would be a high concentration of cesium chloride source material in a confined area, which would require storage facilities to increase their security measures. When cost-effective alternative technologies are available, it may defer the acquisition of new cesium chloride devices, eliminating the need for facilities to heighten security measures.
Closing Remarks by NRC Representatives
The NRC concluded the meeting by stating that if cesium chloride sources are to be phased out, it should be done over time, taking into consideration the availability and practicability of alternative sources or technologies. The agency expects to publish recommendations developed from the workshop and written comments received to the NRC Commissioner within the next few months.
Summary Results of AABB Blood Irradiator Survey
AABB surveyed more than 1,200 member company transfusion services and blood banks, yielding 345 responses. The list was specifically culled so it would not replicate surveys by the American Red Cross and America’s Blood Centers, which independently surveyed their centers concerning irradiator use. Therefore, the AABB survey disproportionately represents hospital users and likely accounted for more that 50 percent of the free-standing cesium devices currently licensed. These facilities either maintain an irradiator within their department or elsewhere in the facility.
Of the respondents, 195 irradiate blood products in-house with 147 (79.5 percent) using cesium-137 and 25 (13.5 percent) using X-ray technology, while 118 (74.2 percent) use another facility as their backup and 23 (14.5 percent) do not have a backup mechanism. This correlates well with the response that 75.4 percent of the respondents provide backup irradiator services for other facilities; the majority of the backup service is accomplished through cesium-137 irradiators.
Of the responses from centers with a cesium-137 irradiator, 99 (76.2 percent) do not have plans to replace their current irradiator. Among those that plan to replace their irradiator 81.3 percent plan to do it within the next five years, with replacement split between cesium-137 and X-ray. The majority (62.5 percent) cited regulatory/compliance concerns as the reason for replacing the current irradiator with source degradation and upgrade of equipment as secondary reasons.
Operationally, the cesium-137 irradiator appears to be more cost-effective and reliable than the alternative, X-ray. An annual service contract for cesium irradiators costs less than $10,000 for 74.6 percent of the respondents, and 23 percent pay between $10,000 and $25,000. The downtime of the cesium irradiator is lower, with 92.4 percent down less than two days and only 5 percent nonoperational for greater than 30 days. Those facilities that have decommissioned or moved an irradiator experienced a cost of less than $25,000 (73.6 percent) and a time period of less than one month (70.6 percent) but it was reported to take longer than three months in some instances (13.7 percent).
In contrast, X-ray irradiators on the average cost more to maintain. An annual service contract for an X-ray irradiator costs less than $10,000 for 61.5 percent of the respondents, but 38.5 percent pay $10,000 to $25,000. However, the vast majority (84.6 percent) of the service contracts do not include the replacement of the X-ray tube and/or power source, which are the parts that are most prone to require frequent replacement. The cost to replace the X-ray tube and/or power source ranged from less than $10,000 to $40,000 (83.3 percent) with 16.7 percent reporting costs of greater than $40,000. X-ray irradiators are nonoperational more often than cesium-137 irradiators — 78.6 percent responded that their irradiator was nonoperational from zero to two days annually, with 21.4 percent nonoperational for greater than 30 days.