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End of Life Decisions for Sealed Radioactive Sources

Pryor, Kathryn H.*

doi: 10.1097/HP.0000000000000398
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Sealed radioactive sources are encountered in a wide variety of settings—from household smoke detectors and instrument check sources through fixed industrial gauges, industrial radiography, and well logging sources, to irradiators and medical teletherapy devices. In general, the higher the level of activity in the sealed source, the stricter the regulatory control that is applied to its use, control, and ultimate disposition. Lower levels of attention and oversight can and do lead to sources ending up in the wrong place—as orphan sources in uncontrolled storage, disposed in a sanitary landfill, melted down in metal recycling operations and incorporated into consumer products, or handled by an unsuspecting member of the public. There is a range of issues that contribute to the problem of improper disposal of sealed sources and, in particular, to disused source disposal. Generally licensed sources and devices are particularly at risk of being disposed incorrectly. Higher activity generally licensed sources, although required to be registered with the U.S. Nuclear Regulatory Commission (NRC) or an Agreement State, receive limited regulatory oversight and are not tracked on a national scale. Users frequently do not consider the full life-cycle costs when procuring sources or devices and discover that they cannot afford and/or are unwilling to pay the associated costs to package, transport and dispose of their sources properly. The NRC requirements for decommissioning funding plans and financial assurance are not adequate to cover sealed source transport and disposal costs fully. While there are regulatory limits for storage of disused sources, enforcement is limited, and there are only limited financial incentives in a small number of states for owners to dispose of the sources. In some cases, the lack of availability of approved Type B shipping casks presents an additional barrier to sealed source disposal. The report of the Disused Sources Working Group does an excellent job of framing these issues (www.disusedsources.org/wp-content/uploads/2014/12/DSWG-Report-March-2014.pdf). This article reviews both the issues and the report’s recommendations, which are designed to improve sealed source control and encourage proper disposal of disused sources.

*Radiation Protection Division, Pacific Northwest National Laboratory, P.O. Box 999, MSIN J2-40, 902 Battelle Boulevard, Richland, WA 99352.

The author declares no conflicts of interest.

For correspondence contact the author at the above address, or email at kathy.pryor@pnnl.gov

(Manuscript accepted 9 September 2015)

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INTRODUCTION

SEALED RADIOACTIVE sources are encountered in a wide variety of settings, including the oil and gas industry, manufacturing, nuclear power, medicine, research, and academic institutions. They are fabricated into devices with a wide range of physical sizes and levels of activity—from household smoke detectors and instrument check sources through fixed industrial gauges, industrial radiography cameras, well logging sources, to irradiators and medical teletherapy devices. Sealed radioactive sources eventually decay to the point where they are no longer usable for their intended purpose, or the devices in which they reside may become old and inoperable. At some point, sealed radioactive sources come to the end of their useful life.

There are an estimated two million sealed radioactive sources in the United States today, and tens of thousands of these are believed to be disused or orphaned (DSWG 2014). Disused sources are those that cannot be used for the practice for which authorization was granted. Orphan sources are those that are not under regulatory control, either because they have never been under regulatory control or because they have been abandoned, lost, misplaced, stolen, or transferred without proper authorization.

When sealed radioactive sources arrive at the end of their useful life, they are often returned to the manufacturer for recycling and reuse. Ultimately, they must be legally disposed in a licensed radioactive waste site. Unfortunately, this does not always occur, and sealed sources can end up in the wrong place—stockpiled in storage, abandoned in place, or improperly disposed in landfills or the environment at large.

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CONSEQUENCES OF IMPROPER DISPOSAL

The loss of control and improper disposal of sealed sources can impact both workers and the public at large. There have been many well publicized events in which sealed sources were lost or stolen, both domestically and internationally, ultimately resulting in injuries and deaths to unsuspecting members of the public.

One consequence of the loss of control and improper disposal of sealed sources is the potential for inadvertent melting of the source and subsequent incorporation into metals. Lubenau and Yusko (1995, 1998) have prepared an extensive review of inadvertent meltings of sealed sources in two previous papers. There have been more than 100 instances of inadvertent meltings reported during the period from 1982–2011, with 36 of those occurring in the United States and 73 occurring internationally (Yusko 2015). There have been a number of near misses as well: cases in which sealed sources, devices containing sources, or discrete sources have been discovered in metal scrap before they could be melted down. It is estimated that many more instances go unreported.

Fig. 1 shows the distribution of industries that have been affected by inadvertent meltings as of 2012. The steel industry has been disproportionately affected with ~80% of the occurrences, followed by the aluminum recycling industry. Fig. 2 shows the predominant radioisotopes that have been involved in inadvertent meltings. Cobalt-60 (60Co) and 137Cs have been the most frequent types of sources involved in accidental meltings. In these cases, the 60Co ends up being alloyed into the ferrous products, while the 137Cs generally volatilizes and is entrained with the furnace dust. The furnace dust is typically collected and recycled to recover metals such as zinc, but if the dust is contaminated with radioactive material, recyclers will not accept it.

Fig. 1

Fig. 1

Fig. 2

Fig. 2

In response to this problem, scrap metal recycling facilities added sensitive radiation monitors to scan incoming feed material, outgoing products and byproducts/waste. This has proven to be quite successful in minimizing the potential for sealed sources to enter the facility undetected, as well as contaminated byproducts from exiting. The addition of radiation monitoring capability has been a significant financial commitment for the recyclers, including the cost of equipment, training of operators, and maintenance. However, cleanup costs for decontamination and disposal resulting from inadvertent meltings of sealed sources can run into the tens of millions of dollars, often requiring the facilities to be shut down during this time, resulting in additional revenue losses. Estimated costs associated with an inadvertent melting event have averaged $12M, up to a high of $23M (as of 1998) (Lubenau and Yusko 1995). Sealed sources can remain undetected, however, in very dense scrap metal or if deeply buried in the incoming scrap metal volume. Use of a radiation monitor on the grapple for the scrap metal can improve the likelihood of detecting sealed sources in the incoming recycling material (Turner 2006).

Inadvertent melting of sealed sources and subsequent byproducts has resulted in the production of contaminated consumer products. A number of examples have been documented in Lubenau and Yusko (1995, 1998) and include steel cookware and shovels fabricated from contaminated steel coils in Pennsylvania and Ohio in the late 1990s and contaminated steel rebar from Juarez, Mexico, and Taiwan in the 1980s. While domestic production of contaminated consumer products has not been discovered in recent years, the importation of contaminated products that were produced overseas has occurred. In 2011, 60Co-contaminated tissue-box holders and pet food bowls from India were discovered to have been distributed in the United States by a major retailer. These contaminated consumer products were primarily discovered through monitoring at the U.S. borders. However, monitoring was not 100% effective in preventing distribution and sales, since not every vehicle is monitored.

The consequences of inadvertent meltings and subsequent production and distribution of contaminated consumer products range from a lack of consumer confidence to financial losses. However, more significant health consequences can result from loss of control and improper disposal of sealed sources, including serious injuries or deaths to members of the public. Examples include a contamination incident in Ciudad Juarez, Mexico, in 1983, involving the disassembly of a 60Co teletherapy unit for scrap. Disassembly resulted in breaching the 60Co source and dispersing the approximately 6,000 pellets, each containing 2.6 GBq of activity. This incident resulted in high radiation exposures to scrapyard workers and residents in the adjoining neighborhood, ranging from 0.13–5.5 Gy, and severe local radiation injury to one of the workers’ hands (Lubenau and Yusko 1995). Another incident was documented in Goiânia, Brazil, in 1985, involving the breaching of a 137Cs source and subsequent dispersion of CsCl2 powder over a wide area of one district of the city (IAEA 1988). This incident resulted in four deaths and injuries significant enough to warrant admission to the hospital for 14 others. Sealed sources that are lost from positive control could also potentially end up diverted and used in a radiological exposure device or radiological dispersal device or contaminating the environment in the event of breach of the source’s confinement barrier.

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FACTORS CONTRIBUTING TO IMPROPER DISPOSAL

There are a range of issues that contribute to the problem of improper disposal of sealed sources and, in particular, to disused source disposal. A discussion of these factors follows.

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Sources and devices used under general licenses

Certain types of sealed sources are manufactured and distributed under a specific U.S. Nuclear Regulatory Commission (NRC) or Agreement State license, which authorizes distribution to persons “generally licensed” to use them. These generally licensed (GL) devices range from exit signs, static eliminators and in vitro testing kits to industrial gauges and measuring and controlling devices. The types of sources and applicable requirements for sources that can be used under a general license are contained in Title 10, Code of Federal Regulations, Part 31 (USNRC 2014a) or equivalent Agreement State regulations. The sources in GL devices are particularly at risk of loss of control and improper disposal due to the lack of regulatory control exercised over the devices.

There are no defined upper limits on the amount of activity that a GL device can contain. Fixed industrial gauges and devices, such as level and thickness gauges, typically contain significant quantities of radioactive material, up to and including IAEA Category 3 quantities (IAEA 2004). Activity in GL devices is limited in practice to less than Category 2 quantities due to the additional regulations that are imposed on Category 1 and 2 sources under 10 CFR Parts 20 and 37 (USNRC 2014a). The GL devices receive a sealed source and device evaluation by the NRC (or Agreement State) before they can be manufactured and distributed for use under a general license.

Measuring, gauging and controlling devices that exceed a certain activity threshold must be registered with the NRC or Agreement State under the requirements of 10 CFR 31.5 (or equivalent). However, registration is not equal to licensing and requires far less information to be submitted on behalf of the applicant than that of a specific license application. The primary information submitted includes details about the device (model, serial number, radioisotope, and activity), location of use, and certification by the “responsible representative” that they are aware of the requirements of the general license. The registration process does require an annual update (and payment of the annual registration fee), as well as verification of location through a physical inventory and checking of the label information. The NRC or Agreement State also imposes requirements for leak testing, recordkeeping, notification of transfer, loss or theft, and proper disposal of the device through 10 CFR 31.5 (or equivalent). These greater activity GL sources, although registered with the NRC or Agreement State, receive minimal to no regulatory oversight.

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Sealed source tracking systems

There is a lack of a comprehensive sealed source tracking system in the United States that includes all sources of concern from both security and public health hazard perspectives.

The National Source Tracking System (NSTS) is managed by the NRC and is designed to track certain sealed sources from manufacture (or importation) through their ultimate disposition. Currently, 10 CFR 20 requires only IAEA Category 1 and 2 sources to be entered into the NSTS; there is no requirement to track Category 3 sources or aggregates of sources that meet the threshold for Category 3 (USNRC 2014a). The NSTS sources are estimated to represent only ~4% of all sealed sources that are licensed in the United States (DSWG 2014).

U.S. Department of Energy (DOE) owned sealed sources are tracked under the DOE Radiological Source Registry and Tracking (RSRT) System in accordance with DOE Order 231.1B (USDOE 2011). DOE contractors are required to report all accountable sources under 10 CFR 835 into the RSRT on an annual basis (USDOE 2014). Those that meet Category 1 or 2 criteria are then reported into the NSTS by the DOE. In addition, DOE contractors must report any transactions involving Category 1 or 2 sources into the RSRT within five working days of the transaction, so that the DOE can update the NSTS in a timely manner.

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Financial issues

A number of financial issues contribute to the problem of long-term storage and failure to properly dispose of sealed sources. One underlying issue is the failure of buyers to consider the full life-cycle costs of acquiring a sealed source. It is relatively easy to purchase a sealed source, particularly a GL device. In contrast, it is much more difficult and expensive to dispose of a sealed source at the end of its useful life. Costs for packaging and transport of the source or device back to the manufacturer can be significant. Transport and disposal costs can run into the tens of thousands of dollars, far exceeding the purchase price of the source itself. Higher activity sources are required to be transported in a U.S. Department of Transportation Type B shipping container. Licensees have discovered that Type B shipping containers are in very short supply, and rental costs have risen sharply in recent years (e.g., $25K to $100K per shipment) (DSWG 2014).

There are no coordinated reuse or recycle programs where sealed sources can easily be transferred to new owners, and there is also a lack of financial incentives to encourage licensees to reuse, recycle or dispose of their sources. In most states, licensees do not pay an annual possession fee per source; owners of registered GL devices only need to pay a nominal annual registration fee, and nonregistered GL devices do not require any fee payment. As a result, sealed source owners tend to store sources that are no longer in use for extended periods of time. Even if the sealed sources are returned to the manufacturer, they frequently end up stockpiled in storage rather than recycled or sent for disposal. It is much less expensive to store disused sources than it is to package, transport and dispose of them. In some cases, the licensee goes out of business or files for bankruptcy and abandons the stockpiled sources in place.

Under 10 CFR 31.5, GL devices are subject to a 2 y storage limit when they are removed from use (USNRC 2014a). In practice, compliance with this requirement is neither inspected nor enforced by the regulatory agencies. There is also a provision exempting GL devices that are kept in standby for future use if the general licensee performs quarterly physical inventories (compliance with which is also neither inspected nor enforced). There is no similar regulatory limit on storage of disused sources by specific licensees; 10 CFR 36 only imposes decommissioning requirements in the event of license inactivity (USNRC 2014a).

The NRC requirements for licensee decommissioning funding plans and financial assurance are found in 10 CFR 30.35 (USNRC 2014a). The financial assurance requirements at the national level are applied to holders of specific licenses who possess very large quantities of radioactive material, and they do not apply to the majority of sealed source users (DSWG 2014). The amount of financial surety required for licensees holding sealed sources is currently $113K, which is not adequate to cover their packaging, transport, and disposal costs in many cases.

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POTENTIAL SOLUTIONS

The Low Level Radioactive Waste Forum Disused Sources Working Group (DSWG) published a comprehensive report in March 2014 on the issues associated with the management of disused sealed sources (DSWG 2014).§ This report also provides a number of recommendations designed to improve sealed source control and encourage proper disposal of disused sources. The DSWG began the implementation phase of its project in April 2014, with broad goals to educate regulators and stakeholders on the true life-cycle costs of sealed sources and potential reuse, recycling and disposal opportunities, and to open a dialogue with regulatory agencies and stakeholders regarding implementation of the report’s recommendations. A discussion of a number of the recommendations contained in the DSWG report follows.

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Increase regulatory control over sealed sources

There have been a number of proposals to increase regulatory control over higher activity sealed sources in recent years. At present, only Category 1 and 2 sources require specific licenses and entry into the NSTS. In 2005, the Organization of Agreement States petitioned the NRC to require specific licensing of higher activity GL devices to enhance control and accountability of these sources (USNRC 2005). In 2009, the NRC proposed to amend 10 CFR 31 to limit the amount of byproduct material contained in a GL device to less than one-tenth of the Category 3 thresholds and to require specific licensing of devices exceeding this quantity (USNRC 2009a). The NRC staff also recommended expanding the NSTS to track all transactions involving Category 3 sources (USNRC 2009b). None of these recommendations were approved by the Commission.

The DSWG report recommends that all Category 3 level sources should be specifically licensed. Specific licensing requires more comprehensive information to be submitted by the applicant (licensee), as well as more stringent oversight on the part of the regulatory authority. In addition, the DSWG report recommends extending the 2‐y limit on storage of disused sources to all Category 1 through 3 sources (GL as well as specifically licensed) and to strengthen enforcement in this area. Manufacturers and suppliers should be required to dispose of sources with no recycle or reuse value on an annual basis rather than stockpile them in long-term storage.

Some Agreement States have already taken steps to develop and implement more comprehensive regulations for sealed sources, including GL sources/devices. The State of Oregon imposes possession fees for each source that a licensee possesses (State of Oregon 2015). The State of Texas levies fees on licensees to fund a perpetual care account that covers the costs associated with abandoned sources and radioactive materials (State of Texas 2007). Florida has established a radiation protection trust fund to cover costs associated with recovery of abandoned sources and radioactive materials in the event of licensee bankruptcy (State of Florida 2014). The DSWG report recommends that the NRC and Agreement States require licensees to pay an annual possession fee for each source they own in order to encourage licensees to dispose of disused sources in a timely manner.

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Financial assurance requirements

The financial assurance requirements in 10 CFR 30.35 need to be updated to more accurately reflect the costs for packaging, transport and disposal of sealed sources. The requirement to provide adequate financial assurance should be applied to all Category 1 through 3 sources. This issue was previously identified in the 2006 Report of the Radiation Source Protection and Security Task Force (USNRC 2006) and was closed in the 2010 report (USNRC 2010), but no action was taken by the NRC to revise 10 CFR 30.35 at that time. The recommendation to require adequate financial assurance for Category 1 and 2 sources was included in the 2014 Report of the Radiation Source Protection and Security Task Force (USNRC 2014b).**

Some Agreement States have already imposed more stringent financial assurance requirements. The State of Illinois requires that licensees submit a reclamation plan and a cost estimate if they possess sealed sources in aggregate quantities greater than 37 GBq (State of Illinois 2005).

The Conference of Radiation Control Program Directors, Inc. (CRCPD) has established a working group that is in the process of developing revised criteria for financial surety requirements that provide cradle-to-grave accountability and proper disposal of all sealed sources, including aggregate quantities of sealed sources.††

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Waste disposal options

In previous years, the lack of access to low-level radioactive waste disposal sites was a barrier to disposing of sealed sources properly. Licensees in noncompact states had few (if any) options for disposal. The opening of the Waste Control Specialists Site in West Texas in 2012 provided a path for licensees in noncompact states to dispose of disused sources. The Waste Control Specialists Site accepts Class A, B, and C low-level wastes from generators outside of the Texas-Vermont compact. In addition, the EnergySolutions Site in Clive, Utah, was granted a 1‐y variance to accept Class A sources under the Source Collection and Threat Reduction (SCATR) Program from licensees/shippers outside of the Northwest compact (State of Utah 2014). EnergySolutions is seeking to permanently remove restrictions on the disposition of Class A sealed sources at the Clive Facility.

The NRC issued a revision to the Branch Technical Position (BTP) on Concentration Averaging and Encapsulation in February 2015 (USNRC 2015).‡‡ This revision describes acceptable methods to perform concentration averaging of low-level waste in order to determine the waste class for disposal and removes some of the constraints associated with disposal of higher activity sealed sources in licensed low-level waste disposal sites. The BTP increases the Class C limits for disposal of 137Cs sealed sources, which are commonly used in research, medicine, and industry, from 1.1–4.8 TBq. The DSWG report recommends adoption of the BTP and encourages states with Class B and C low-level waste disposal sites to implement the alternative approaches methodology to potentially allow disposal of higher activity sources.

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Recycling, reuse and alternative technologies

The DSWG and the Radiation Source Protection and Security Task Force reports recommend that technologies should be developed as an alternative to using Category 1 through 3 sealed sources. The National Nuclear Security Administration (NNSA) has taken a leading role in the development of alternative technologies. Further, incentives should be developed to encourage potential buyers to use alternative technologies instead of purchasing a new source where it is appropriate to do so. Opportunities for reuse and recycling of sealed sources should be expanded through establishment of a national source exchange program.

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Type B shipping containers

The limited availability of Type B shipping containers should be improved, as this is an obstacle to the transportation and disposal of high activity sources. The process for designing, developing, reviewing and approving new Type B package designs can take years to complete, and the process should be expedited. The 2014 Report of the Radiation Source Protection and Security Task Force notes that progress has been made by NNSA in the development of two new Type B packages recently, and projects that these containers will be certified in the next 2 y (USNRC 2014b). In this regard, in July 2014, NNSA’s Off-Site Source Recovery Project (OSRP) received a Certificate of Compliance from NRC for one of its Type B Containers, the 435B, which will be used to over-pack shielded devices containing radioactive sealed sources (such as blood irradiators).

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Sealed source recovery/disposal programs

Two programs, the OSRP and the SCATR Program, are currently operating to collect and dispose of disused or abandoned sealed sources.

The OSRP is sponsored by the NNSA Office of Radiological Security and is managed by the Los Alamos National Laboratory. The mission of the OSRP is to remove excess, unwanted, abandoned, or orphaned sealed sources that pose a potential risk to health, safety and national security. This program originated from early efforts by Los Alamos National Laboratory to recover and dispose of excess 239Pu sealed sources distributed under the “Atoms for Peace” Program (Whitworth et al. 2009). The initial scope of the OSRP was to recover and dispose of sealed sources that were classified as Greater than Class C low-level radioactive waste and primarily focused on transuranic sources. After 11 September 2001, the mission of OSRP was expanded to include public safety and national security considerations and includes recovery of high activity beta/gamma-emitting sources (OSRP 2015). The NNSA acquired responsibility for the OSRP in 2003. The OSRP also recovers disused foreign-owned sealed sources of U.S. origin.

Source recovery under OSRP is prioritized based on the activity of the source and the security threat that it poses. As of March 2015, the OSRP has recovered 30,840 sources in the United States and 2,866 international sources (OSRP 2015).

The SCATR Program is operated under a cooperative agreement between the CRCPD and the NNSA. It has been in existence since 2007 and provides a pathway for licensees to dispose of Class A, B and C disused or unwanted sources that are below the Category 2 threshold. The licensees must register their sealed sources with the OSRP to be considered for participation in the SCATR Program. The CRCPD then selects waste brokers to collect the sources from selected licensees, who then package, transport and dispose of the sources. The program is funded by a grant from the NNSA, which provides cost-sharing support for the licensees. Funding for cost sharing has decreased over the years in which the SCATR Program has operated and is expected to continue to decrease. Under the SCATR Program, nearly 14,000 sources have been collected and disposed.

The SCATR Program has been extremely successful in encouraging licensees to dispose of their inventories of disused sources, particularly due to the financial assistance from the NNSA grant for cost sharing. The DSWG report notes that while both the OSRP and SCATR Program have provided significant contributions to the disposition of unwanted and disused sources, licensees who use these programs are not bearing the full life-cycle costs of source ownership. They may choose to wait to dispose of their disused sources until the next round of the program underwrites some of their costs to do so. This may result in an unintended disincentive to promptly reuse, recycle or dispose of sealed sources in a timely manner. The report recommends that NNSA continue to fund the recovery of sources that do not meet the waste acceptance criteria for commercial low-level waste disposal sites, but it suggests that a portion of the funding be directed toward some type of educational outreach program for licensees on the life-cycle obligations associated with owning sealed sources.

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CONCLUSION

The loss of control and improper disposal of sealed sources continues to present challenges. While most licensees dispose of their sources in compliance with the regulations, there are still large numbers of disused sources that remain stockpiled rather than sent for disposal. Disposal options now exist for licensees in all 50 states to dispose of Class A, B, and C sealed sources, but the shortage of Type B shipping containers remains a barrier to the transport of high activity sources.

Increased regulatory control and NSTS tracking of Category 3 sources should be strongly considered. Requiring specific licensing of Category 3 sources could also aid in reducing the potential for GL devices to become lost or abandoned. Financial assurance requirements for sealed sources should be strengthened to reflect the true costs of packaging, transport and disposal. The availability of Type B shipping containers should be improved and expedited. Opportunities for reuse and recycling should be expanded through some type of national exchange program. Funding should continue for NNSA activities for recovery and collection of orphaned, abandoned and disused sources, including both the OSRP and the SCATR Program.

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REFERENCES

Disused Sources Working Group. Low-Level Radioactive Waste Forum, report of the Disused Sources Working Group. Ft. Lauderdale, FL: DSWG; 2014.
International Atomic Energy Agency. The radiological incident in Goiânia. Vienna: IAEA; STI/PUB/815; 1988.
International Atomic Energy Agency. Code of conduct on the safety and security of radioactive sources. Vienna: IAEA; 2004.
Lubenau JO, Yusko JG. Radioactive materials in recycled metals. Health Phys 68: 440–451; 1995.
Lubenau JO, Yusko JG. Radioactive materials in recycled metals—an update. Health Phys 74: 293–299; 1998.
Off-Site Source Recovery Project. Off-Site Source Recovery Project overview [online]. 2015. Available at http://osrp.lanl.gov/. Accessed 25 March 2015.
State of Florida. Florida Code, Title XXIX Public Health, Chapter 404, Radiation, 404.122, Radiation Protection Trust Fund. 2014. https://www.flsenate.gov/Laws/Statutes/2012/404.122. Accessed on 30 November 2015.
State of Illinois. Title 32: energy, chapter ii: Emergency Management Agency, subchapter B: radiation protection. 2005. ftp://www.ilga.gov/JCAR/AdminCode/032/03200330sections.html. Accessed on 30 November 2015.
State of Oregon. Oregon rules for the control of radiation in GL devices. OAR‐333‐102‐0115; 2015. http://arcweb.sos.state.or.us/pages/rules/oars_300/oar_333/333_102.html. Accessed on 30 November 2015.
State of Texas. Texas statutes, Title 5, Subtitle D, Chapter 401, Subchapter H; 2007. http://www.statutes.legis.state.tx.us/Docs/HS/htm/HS.401.htm. Accessed on 30 November 2015.
State of Utah. Utah Department of Environmental Quality. Letter dated 29 September 2014, from R. Lundberg to DB Shrum, “Response to request to extend the variance to receive and dispose of sealed sources, radioactive materials license #UT 2300249, license condition 16A” [online]. Available at www.deq.utah.gov/businesses/E/EnSolutions. Accessed 25 March 2015.
Turner R. Scrap metals industry perspective on radioactive materials. Health Phys 91: 489–493; 2006.
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U.S. Nuclear Regulatory Commission. Limiting the quantity of byproduct material in a generally licensed device. Washington, DC: USNRC; NRC‐2008‐0272‐0001; 2009a.
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U.S. Nuclear Regulatory Commission. The 2014 Radiation Source Protection and Security Task Force Report. Washington, DC: USNRC; 2014b.
U.S. Nuclear Regulatory Commission. Concentration Averaging and Encapsulation Branch Technical Position, revision 1 volume 1. Washington, DC: USNRC; 2015.
Whitworth J, Streeper C, Cuthbertson A. 10 years and 20,000 sources: the GTRI Offsite Source Recovery Project. Los Alamos, NM: Los Alamos National Laboratory; LA-UR‐09‐04134; 2009.

Personal Communication, J.G. Yusko. Melts (2012‐01). Excel spreadsheet, personal communication. 2015.
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As part of its National Level Exercise, Liberty RadEx, that occurred in Philadelphia in April 2010, a methodology was developed by the EPA to generate a first-order estimate of a waste inventory for the hypothetical radiological dispersal device from the exercise scenario. Determination of waste characteristics and whether the generated waste is construction and demolition debris, municipal solid waste, hazardous waste, mixed waste, or low level radioactive waste, and characterization of the wastewater that is generated from the incident or subsequent cleanup activities will all influence the cleanup costs and timelines. Decontamination techniques, whether they involve chemical treatment, abrasive removal, or aqueous washing, will also influence the waste generated and associated cleanup costs and timelines. For additional information, please contact Paul Lemieux of the EPA at lemieux.paul@epa.gov or at (919) 541-0962.
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§For a copy of the Disused Sources Working Group report, please go to: http://www.disusedsources.org/wp-content/uploads/2014/12/DSWG-Report-March-2014.pdf.
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**The 2014 Radiation Source Protection and Security Task Force report can be downloaded online at http://www.nrc.gov/security/byproduct/2014-task-force-report.pdf.
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††Personal communication, Conference of Radiation Control Program Directors, A. Grumbles, Chair, CRCPD Working Group SR-S. Frankfort, KY: CRCPD; 2015.
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‡‡The revised Concentration Averaging and Encapsulation BTP can be found online at http://www.gpo.gov/fdsys/pkg/FR-2015-02-25/pdf/2015-03913.pdf.
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Keywords:

National Council on Radiation Protection and Measurements; radioactive materials; waste management; waste storage

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