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INTRODUCTION
The National Research Council Committee on the Impact of Low-Level Radioactive Waste Management Policy on Biomedical Research in the United States was asked to assess the effects of the current management policy for LLRW, and resulting consequences, such as higher LLRW disposal costs and onsite storage of LLRW, on the current and future activities of biomedical research. The committee heard from researchers, state and institutional officials, and radiation safety officers regarding the effects of the existing LLRW disposal situation, including the effects of the lack of access to disposal facilities on institutions that conduct biomedical research and on hospitals where radionuclides are crucial for the diagnosis and treatment of disease.
Background of this Report
For the last 20 years, many groups—including generators of LLRW, environmental groups, elected state officials, radiation-safety officers, and private citizens—have been engaged in the difficult and often contentious problem of what to do with LLRW. Efforts to site and open new disposal sites for LLRW are deadlocked. Although there has been concern among stakeholders about the continuation of access to reasonably priced disposal capacity, the current system, which uses the existing capacity has posed no health or safety issue.
Currently, three facilities accept LLRW for disposal in the United States. They are in Barnwell, South Carolina, Richland, Washington, and Clive, Utah. If access to disposal facilities were to be interrupted, LLRW targeted for disposal would add to the waste that has already accumulated in temporary storage facilities in numerous hospitals and universities across the United States. Research organizations would probably continue to find ways to reduce, treat, and store their LLRW for the near term, but with some unknown level of added costs and management challenges. Interruption of access to disposal sites would necessitate the expansion of temporary storage facilities that are in common use today for decay of short-lived materials.
These practices have been followed and improved since the 1980s when costs of managing LLRW increased dramatically and disposal sites began to close. Biomedical researchers in particular are facing increasing disposal charges. In addition, LLRW wastes are sometimes mixed with chemicals, such as volatile solvents or exhibit the characteristics of hazardous materials as defined under federal law, Resource Conservation and Recovery Act (RCRA) (40 CFR 261, subpart C) (USEPA, 2000). Although the biomedical community does not generate a large amount of mixed waste, it nevertheless, presents unique and difficult challenges.
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The increasing costs of biomedical research LLRW management, including concern for continued disposal facility access to storage and disposal sites, costs of developing or expanding storage and treatment, and costs of disposal should be expected to continue to have effects on the use of radioactive materials for diagnosis and treatment of disease and for research. Alternatives to using radioactive material will most likely be selected more often, and longer-lived radioactive materials could become less desirable to use.
The waste-disposal plan set in motion in 1980 by Congress in the Low-Level Radioactive Waste Policy Act (LLRWPA, Public Law 96-573) and the Low-Level Radioactive Waste Policy Amendments Act of 1985 (LLRWPAA, Public Law 99-240) charged the states with the responsibility for LLRW disposal and gave them the right to form regional compacts with other states to share a disposal facility. By 1998, 42 states had formed 10 compacts. Seven unaffiliated states, the District of Columbia, and Puerto Rico remained individually responsible for their radioactive waste (LLW Forum Summary Report, 1998). However, no state or compact is actively developing a site, and it is not clear whether a new site will open soon. Nonetheless, all generators currently have access to disposal. Long-term access to disposal facilities, however, is uncertain. The development of future disposal capacity poses complex problems of public education and acceptance, financial costs, and the need for the capacity. Capacity (available disposal space in licensed disposal sites) has never been at issue with respect to LLRW, but access to existing capacity at manageable costs has been.
This report of the Committee on the Impact of Low-Level Radioactive Waste Management Policy on Biomedical Research in the United States, was commissioned to assess impacts of future access to the current LLRW-disposal capacity on biomedical research. In assessing the current LLRW management policy, one needs to recognize that the LLRW controversy is overwhelmingly focused on the nuclear-power industry. The amount of biomedical LLRW, measured in volume, is less than 5-10% of the total LLRW disposed, and the quantity of radioactive materials disposed is no more than a few percent of the total disposed and generated in the US (OTA, 1989; Fuchs, 1999). Public policy regarding LLRW tends to focus on the nuclear-power aspect of the question, so biomedical research is likely to continue to struggle to find ways to adapt to the policy and regulatory environment dictated by the nuclear-power debate.
The current policy of biomedical-LLRW disposal creates several burdens. One is on regulators, who must oversee a widely distributed system. Storage-for-decay facilities have been successfully operated in conformance with regulations in many states and at many institutions; but as they become more numerous and the types and quantities of wastes managed become more varied and larger, the challenge for regulators to inspect and to ensure conformance with requirements will increase.
Another burden is on research institutions, which have to fund and maintain facilities for storage and disposal of LLRW. Most academic institutions pass some or all of the direct costs for LLRW disposal to investigators via recharges. When this is the case, these costs compete directly with other research activities of the investigator.
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Furthermore, the administrative infrastructure to support waste disposal programs (oversight committees, administrative staff, etc.) is generally supported by the administrative overhead component of indirect costs charged to grants. This component is within the capped portion of federal indirect cost calculations (OMB Circular A-21, 2000), thus limiting the institutional capacity to find additional resources to build these programs.
It is crucial to understand that the process of LLRW-disposal management policy must make financial sense. The current economic model evolved on the bases of the use of short-lived radionuclides except 14C (carbon-14) and 3H (tritium). If use of radionuclides increases substantially because of the larger national commitment to biomedical research or because of the introduction of new radionuclide-dependent assays or methods, or if the use of longer-lived radionuclides increases for any reason, the current system will be challenged. Policy and regulatory bodies need to understand the economic basis of LLRW-disposal policy if they are to modify the system in the event of major new needs.
Although disposal capacity appears to be sufficient for the biomedical needs of the next several decades, the future of commercial-LLRW management policy in the United States is by no means guaranteed. Considering the costs and the political and technical processes necessary to license a facility, new capacity is unlikely to develop quickly. However, research trends are not predictable, and some unforeseen technology might require the introduction of new radioactive materials or increased use of such materials. That possibility is worrisome because our nation is unprepared for a substantial change in the current situation.
Background to LLRW-Management Policy
Radioactive materials contribute in important ways to biomedical research, medical diagnosis and therapy, and industrial and academic activities. For example, radioactive materials are used in biomedical research for the analysis of physiologic and biochemical processes, gene sequencing, enzyme reactions, and pharmacokinetic and cellular process studies. The most commonly used radionuclides for the above example are 32P (phosphorus-32), 33P (phosphorus-33), 3H, 14C, 35S (sulfur-35), and 45Ca (calcium-45). 125I (iodine-125) is used for radioimmunoassay, protein metabolism, hormone, and anatomical imaging studies. Microspheres labeled with 46Sc (scandium-46), 57Co (cobalt-57), 85Sr (strontium-85), 95Nb (niobium-95), 113Sn (tin-113), 153Gd (gadolinium-153), and 141Ce (cerium-141) are used for regional blood-flow studies. 60Co (cobalt-60), 67Ga (gallium-67), 99mTc (technetium-99m), 125I, 123I (iodine-123), 131I (iodine-131), 192Ir (iridium-192), and 201Tl (thallium-201) are used in medical diagnosis and therapy (Miller, 2000, CORAR, 1993). Diagnosis of primary tumors, early detection of metastasis, and studies of metabolic functions such as thyroid function are a few examples (Miller, 2000). New technologies for diagnosis and therapy are being developed, such as more sophisticated imaging techniques and monoclonal-antibody therapies that combine radioactive materials with molecules that target specific diseases. LLRW produced in
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those biomedical uses of radioactive materials, although smaller in volume and radioactivity than reactor-produced LLRW, requires treatment, transportation, and disposal.
LLRW is defined by exclusion. It is radioactive waste that is not high-level radioactive waste (HLRW), not spent nuclear fuel, and not transuranic waste (TRU). Nor does LLRW include uranium-mill tailings waste, naturally occurring radioactive material (NORM), or technologically enhanced NORM (TENORM). LLRW does include everything from very short-lived to very long-lived radionuclides. It includes any radioactive wastes generated from the use of source, byproduct, or special nuclear material that is not in one of the categories listed above. Biomedical LLRW includes residual unused radioactive materials, laboratory solutions containing radioactive materials, counting vials, and animal carcasses containing injected materials; gloves, swipes, and other items that are used during injection in a hospital or clinic; and filters, centrifuge tubes, pipettes, and laboratory trash used during research involving radioactive materials.
LLRW generated in biomedical research is typically of small volume and low radioactive content compared with that generated in the nuclear-power industry, but there are exceptions. Some wastes generated in nuclear power plants, such as housekeeping wastes, contain small quantities of radioactive material in large volumes; and some medical wastes, such as that from manufacturing facilities used to generate medical radionuclides, can contain higher quantities of radioactive material in smaller volumes. Overall, the biomedical-research and medical communities generate small volumes of LLRW containing small quantities of radioactive materials, compared with the nuclear-power industry materials that must be managed under the same regulations.
Because of the increasing costs associated with LLRW disposal and interruption of access for disposal, some generators and researchers have faced difficulties in disposing of their radioactive waste. As a result, effective steps have been taken to decrease volumes of LLRW. The reduction in disposed volumes of LLRW and activities from biomedical institutions in the last 15 years is shown in Table 1. Biomedical-research institutions have made provisions to manage their LLRW in a manner that will assure no disruption to research. Their methods include:
-
Reevaluation of research needs and techniques.
-
Selection, where possible, of short-lived radioactive materials and avoidance of long half-life radionuclides so that wastes generated can be managed by storage for decay.
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A combination of waste-generation avoidance, compaction, and incineration.
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|
Year |
Medical Generators |
Academic Generators |
||
|
Volume, ft3 |
Activity, Ci |
Volume, ft3 |
Activity, Ci |
|
|
1986 |
27,698.03 |
23.21 |
41,799.84 |
107.23 |
|
1987 |
33,963.24 |
24.31 |
58,565.76 |
68.46 |
|
1988 |
24,170.63 |
86.56 |
49,372.54 |
2,282.73 |
|
1989 |
34,730.20 |
149.32 |
66,101.42 |
1,946.44 |
|
1990 |
22,792.13 |
59.45 |
48,555.10 |
1,096.04 |
|
1991 |
28,622.20 |
70.03 |
48,047.94 |
472.13 |
|
1992 |
26,341.24 |
397.77 |
44,248.45 |
1,724.27 |
|
1993 |
4,953.30 |
21.08 |
11,850.83 |
110.25 |
|
1994 |
5,011.77 |
454.93 |
17,793.55 |
420.97 |
|
1995 |
1,923.78 |
6.13 |
7,537.68 |
47.72 |
|
1996 |
2,192.43 |
11.22 |
14,191.24 |
60.80 |
|
1997 |
1,280.56 |
10.40 |
7,446.45 |
61.04 |
|
1998 |
1,456.31 |
9.98 |
4,904.79 |
132.12 |
|
1999 |
970.01 |
4.93 |
10,110.92 |
43.42 |
|
2000 |
147.14 |
2.79 |
5,440.70 |
46.06 |
a Data from http://mims.inel.gov/web/owa/gentype.report. Time period: January 1, 1985 through September 30, 2000.
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Compaction by the generators is encouraged by disposal rates that are based on volume of material. There is no apparent fast-approaching limit on capacity for burial of LLRW that is driving prices. However, there is a physical limit to how much compaction can be accomplished, and further development of this approach must await significant advances in technology. It cannot be determined how this situation might change if a disposal site were closed, although it seems likely that the cost of disposal at remaining open sites would encourage further use of compaction.
This situation is an example of a number of potential problems in disposal that cannot be analyzed at present because too many variables are unknown. Other such potential issues include the possible loss of public confidence if there should be a fire or other untoward event at a disposal site, public reaction to a large increase in radioactive materials that are being stored for decay in research institutions, changes in reimbursement rates for medical procedures that use radioactive materials, or upper limits on the cost for disposal of LLRW that makes either research or medical use of these materials economically impractical. The committee was interested in these questions, but could only speculate on answers to the questions. The committee did note the efforts of radiation safety officers to provide plans for dealing with major problems such as natural disasters in order to minimize health and safety risks under such circumstances.
Over the last 2 decades, there has been success in minimization and improvement in the management of LLRW disposal at several biomedical institutions (Castronovo, 2000, Miller, 2000, Osborne, 2000), and LLRW volumes have been reduced. For example, volumes of 32P and 33P, 35S, 125I, 3H, and 14C waste generated at NEN Life Science Products, Inc., were reduced by 50% from 1989 to 1994; and generation of radioactive waste per unit of radiopharmaceutical product has decreased by about 15% per year (Todisco and Smith, 1995).
Storage for decay is one of the methods used to minimize the volume of waste that will require disposal. There is a financial incentive to minimize waste volume: every dollar spent on disposal is a dollar that cannot be spent on research. The US Nuclear Regulatory Commission allows decay in storage of radioactive materials that have a half-life less than 120 days (USNRC 1999a; Ring et al., 1993; Emery et al., 1992; Edwards et al., 1996; Party and Gershey 1989). Volume reduction by filtration, ion-exchange reverse osmosis, and evaporation are used for aqueous wastes (Bohner et al., 1983; Edwards et al., 1996) and adsorbers or scrubbers are used to retain radioactive gases to optimize for storage of those materials for decay (Miller et al., 1979). Solidification is sometimes used, but it increases the volume of LLRW that must be disposed of.
Animal carcasses pose a particular problem because freezing them until radioactivity decays is acceptable only for carcasses that contain short-lived radionuclides (King et al., 1988; Tries et al., 1996). For those with longer-lived radionuclides, incineration at a licensed offsite disposal facility is the only solution; again, this adds to the cost of dealing with the waste. Other techniques have been developed, including chemical digestion (Kaye et al., 1993), dry distillation (Saito et al., 1995), and freeze-drying (Hamawy, 1995). 14C and 3H in liquid scintillation fluids and animal carcasses can be considered
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nonradioactive if their concentration is less than 0.05 μCi per gram [10CFR20.2005 (USNRC 1999a)].
It is convenient to divide LLRW into categories, as set forth below.
A. Medicine
Diagnosis
In nuclear medicine and imaging procedures, radionuclides that have half-lives of 6-73 hours, such as 99mTc and 201Tl, are used because of their imaging characteristics, and because they are short-lived and do not result in a high dose to the patient compared to the diagnostic benefit of the test. They do not contribute to the volumes of LLRW needing permanent disposal. They are stored for decay typically at the point of generation and then disposed in accordance with the requirements for nonradioactive constituents of the waste.
Positron-Emission Tomography (PET) is an important diagnostic tool. PET scans permit assessment of metabolic functions and are useful in various medical situations, including brain and heart disorders and the need to detect early metastases. Procedures involving PET scans use radionuclides with half-lives of less than 2 hours, such as 15O (oxygen-15), 18F (fluorine-18), and 13N (nitrogen-13). Because of the short half-lives, PET does not pose problems in LLRW management.
Treatment
Many of the radionuclides, such as 131I, 90Sr (strontium-90), 153Sm (samarium153), and 90Y (yttrium-90), used in the treatment of cancer and other diseases do not result in waste that has to be sent to LLRW disposal sites. Monoclonal antibodies tagged with various radionuclides are coming into wider use. 131I-tagged monoclonal antibodies are currently being used in clinical trials for the treatment of non-Hodgkin's lymphoma and other malignant diseases. For inpatient treatment of thyroid diseases, small amounts of 131I wastes are generated and patient excreta may enter into the sanitary sewer as well. These wastes are generally stored for decay.
Wastes are generated at medical radiopharmaceutical-manufacturing facilities, such as those that make the 125I seeds used in cancer treatment and the manufacturers of radionuclides used in basic and applied medical research. These manufacturer wastes do need to be managed, often with treatment and disposal as LLRW. If disposal costs result in a decreased usage of certain radionuclides and products, the continued manufacture of these materials could be at risk.
Sealed sources, such as 60Co, used in cancer therapy may be recycled and do not often go directly to disposal sites. Recycling or disposal decisions, managed by the manufacturers, are generally based on comparative economics for the cost or remanufacturing and later the market value of the sealed source. Although still in use in
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some facilities, 60Co is not as popular as large electron accelerators for primary cancer radiotherapy in the United States.
B. Biomedical Research
Radioactive waste from biomedical research is dominated by comparatively short-lived radionuclides, but some long-lived radionuclides, mainly 3H and 14C, are commonly used in laboratories. A substantial portion of 3H and 14C is managed with direct disposal, incineration, or disposal into sanitary sewers according to 10 CFR 20.2003. The radiopharmaceutical companies that supply the materials for biomedical research generate some LLRW. Specific data on generation rates in the radiopharmaceutical industry were not available to the LLRW committee. However, it is probably safe to assume that this component of the LLRW stream will retain its current proportional relationship to the amount of LLRW generated by research and medical uses. If, for example, there is a great increase in the use of radioactive materials attached to anti-cancer pharmaceuticals, then the industrial, research, and medical generations of LLRW will all increase concordantly.
C. Nuclear Power Plants
Wastes from nuclear power plants differ substantially from the biomedical-research, medical, and industrial waste in the radioactive materials produced and the amounts (in volume and radioactive material quantity) to be managed. Nuclear power facilities generate all three classes of LLRW as defined in 10 CFR 61, which are termed Class A, Class B, and Class C. Each successive class has larger concentration limits for long- and short-lived radionuclides. Class B and Class C are subject to stability requirements for waste form and waste packages that must be met by disposal-site operators. Wastes associated with routine maintenance are typically Class A wastes, which are treated by compaction, supercompaction, or incineration. Consolidated wastes from those processes are disposed of at licensed LLRW facilities. Water-processing operations, such as coolant-water cleanup, tend to generate higher concentrations of radioactive materials in wastes, including ion-exchange resin and other solid wastes. Irradiated hardware removed from reactor cores is typically highly radioactive and contains, for example, 60Co, 63Ni (nickle-63), and 55Fe (iron-55). These are almost always Class C wastes.
