Decommissioning is a controlled process used to safely retire a facility that is no longer needed. During decommissioning, radioactive and hazardous materials, equipment, and structures are decontaminated, isolated, sealed, enclosed, or removed so that the facility does not pose a risk to public health or the environment.
To facilitate decommissioning planning for the BGRR, the project team gathered input on community and stakeholder values during a series of roundtable meetings in the summer of 1999. The results of these meetings are available in a document entitled Summary of Roundtable Discussions on Decommissioning of the BGRR (BNL, 1999i). This input has been considered during the evaluation and screening of decommissioning alternatives. Additional opportunities for public input will arise as the project proceeds.
Along with public input, the following broad categories of evaluation criteria were considered in assembling decommissioning alternatives:
In keeping with the CERCLA process for removal actions (EPA, 1988b), the standard approach used to develop the removal alternatives evaluated in this document are:
It should be noted that because there are a limited number of accepted methods available for decommissioning of the BGRR (e.g., leave in place, remove, isolate, seal or enclose), Steps 6 and 7 are redundant (i.e., technology = removal, process option = removal). Therefore, for the purposes of assembling BGRR decommissioning alternatives in accordance with both CERCLA and DOE long-term planning and budget allocations, steps 6 and 7 will be combined, and referred to as development of representative process options.
To identify appropriate RAOs, the future land use must be considered. Roundtable meetings with the public, stakeholders, and the project team discussed future land uses. Additional future land use options will be considered after the nature and extent of contamination has been determined at the BGRR facility.
The BGRR facility is located within a developed area of the BNL property. Ranging from 100 to 120 feet above sea level, the BGRR facility was constructed on the highest point of land within the BNL complex. The structures that were constructed to support or be supported by the BGRR include the Reactor Building (Building 701), the Reactor Pile (Building 702), the Reactor Laboratory (Building 703), the Fan House (Building 704), the Reactor Pile Stack (Building 705), the Instrument House (Building 708), the Canal House (Building 709), the Water Treatment Facility (Building 709A), the Hot Laboratory (Building 801), and the Pile Fan Sump.
Future-use options for the BGRR facility may include but are not limited to the following:
Without a complete characterization and risk assessment, assumptions about potential exposure pathways will be based on existing information and thus will be more qualitative than quantitative. The rural residential family-farm scenario recommended as default (ANL, 1993) includes all environmental pathways. A farmer may receive doses from direct external exposure to radiation, inhalation of resuspended dust from surface contamination, inhalation of radon, ingestion of contaminated soil, ingestion of plant foods, ingestion of meat from livestock, ingestion of milk from this livestock, ingestion of water, and ingestion of aquatic animals from a nearby pond that has been contaminated. Since contamination of a nearby pond is unlikely, the exposure pathway "ingestion of aquatic animals" may be eliminated. Figure 2-1 illustrates this scenario.
Further refinements to the scenario should be made based on site conditions. This includes future land use and the nature of the contamination. Other scenarios such as residential without subsistence farming or industrial may be more applicable after these considerations. Figure 2-2 illustrates all the potential pathways to potential human exposure after decommissioning is complete. All the pathways in Figure 2-2 apply to both radioactive and non-radioactive contaminants except for direct external radiation (see Subsection 2.2.1.3).
2.2.1 General Assumptions of the Conceptual Model
This conceptual model will form part of the basis for conducting a qualitative risk analysis of the alternatives under evaluation. The evaluation will include risks to workers, the general public, and the environment. The conceptual model along with site-specific data will be used to develop preliminary remediation goals based on relative dose or risk (see Subsection 2.6). Both the period during and after remediation will be considered. While the risks include both industrial hazards and hazardous substances, only exposure to hazardous radiological and non-radiological substances is considered for exposure pathways.
2.2.1.1 Industrial Hazards
Industrial hazards include falls, electrical shock, confined spaces, hoisting and lifting, heat, noise, transportation accidents, seismic events, high winds, and fire. Some of these possibilities may also lead to release of hazardous substances.
2.2.1.2 Hazardous Substances
Hazardous substances include both radiological and non-radiological contaminants. Subsection 2.3 lists the contaminants of potential concern. Appropriate DCGL values must be derived based on potential short-term doses as well as long-term exposure. While a detailed characterization is not available, the range of radiological contaminant activities shown in the Hazard Classification and Auditable Safety Analysis for Brookhaven Graphite Research Reactor (BGRR) Decommissioning Project, Brookhaven National Laboratory, September 8, 1999 (BNL, 1999f) varies by at least six orders of magnitude from radionuclide to radionuclide. This suggests the list of contaminants of potential concern may be narrowed. Fifty (50) year institutional controls will allow radionuclides with shorter half-lives to decay. Thus, while Co-60 may be a significant contaminant of concern during remediation with its contribution to direct external exposure, in 50 years, due to its five-year half life, only 0.1 % of its present day activity will exist (see Subsection 2.2.1.5). Both Sr-90 and Cs-137 have half-lives around 30 years. These too will disappear quicker than the longer lived isotopes of concern such as C-14 with a 5,700-year half-life, plutonium-239 (Pu-239) with a 24,000-year half-life, and plutonium-240 (Pu-240) with a 6,600-year half-life. For long-term environmental effects, (e.g., chronic human health effects such as cancer, or genetic environmental effects, etc.) long-lived radioisotopes and their progeny need to be addressed.
2.2.1.3 Internal and External Exposure for Radioactive Contaminants
A main difference between radioactive contaminants and other contaminants is that some radioisotopes are a health concern from the direct external effects of radiation emitted from the contaminant as well as the internal effects after an uptake of the contaminant. External effects are primarily from gamma radiation. While many radionuclides emit gamma radiation, the energy of gamma radiation from different radioisotopes varies by many orders of magnitude. Thus, even modest amounts of shielding materials such as soil can eliminate the external effects from isotopes that emit low energy gamma radiation such as plutonium-241 (Pu-241). Internal exposure occurs from the inhalation or ingestion of contamination, and by direct absorption through the skin. Internal effects are primarily from beta and alpha radiation. Internal exposures are from sources such as contamination in drinking water and radon inhalation, or from ingestion of plants and animals that have themselves had an internal deposition. The effects in the body depend on target organs, body retention, radioactive decay, and the radioisotopeâs daughter products.
There are different means for minimizing the effect from external and internal hazards. Shielding by materials such as soil, concrete, lead, steel, etc., can help eliminate the external radiation risks from those radioisotopes such as Co-60 and Cs-137 that present an external hazard. Increasing the distance from a source or decreasing the time spent around a source will also reduce external effects. Preventing the route of entry of a contaminant into the body prevents internal exposure. During remediation, protective clothing, HEPA filtration, and good work practices will be some of the means used to minimize internal exposure.
2.2.1.4 Radioactive Contamination
Materials in a nuclear reactor may contain radioactivity from both activation and contamination processes. Activation is a process by which a material such as steel is made radioactive from the bombardment with neutrons. The neutrons are produced by the fissioning of uranium fuel. Radioactivity is induced throughout the material such that the entire material may be considered radioactive. While activated steel can not be cleaned of its radioactive content, the radioactive content can not be transported unless the steel itself is degraded (e.g., through cutting or abrasion) and transported.
Radioactive contamination generally refers to loose or fixed radioactive material that is transported and deposited onto surfaces. This contamination may result from processes such as abrasion, oxidation or erosion of fission and activation products. Radioactive surface contamination may be easily transported from surface to surface with direct contact. Loose surface contamination such as dust can become airborne contamination and be deposited in other locations. In this document, contamination refers to both activated materials and the material that is transferable or can become transferable. It is important, however, for the alternatives under consideration to make the distinction that activated materials are a greater external exposure concern while contaminated materials are a greater internal exposure concern. Furthermore, during remediation activities such as cutting, jack hammering, and other intrusive techniques, the potential for internal exposure is increased.
2.2.1.5 Radioactive Decay
Radioisotopes naturally decay causing a decrease in their activities or concentrations. Each radioisotope has a unique half-life that is a measure of how long it will take for the half of the radioactive isotope to decay. This can be expressed by the equation:
Where: Ct = Concentration of the radioisotope at time t
Co = The original concentration of the radioisotope at time 0
t = the amount of time that has passed
T1/2 = the half life of the radioisotope in the same units as t (months, years, etc.)
For example, for a radioisotope with a half-life of 5 years, after 50 years, the fraction of concentration left is:
2.2.2 Conceptual Model of Environmental Fate, Transport, and Exposure
This qualitative conceptual model is intended to evaluate the potential human health and environmental hazards associated with the known and suspected contaminants at the BGRR facility. The focus is on the potential contaminant release mechanisms, the pathways, and the associated risks if contamination is released to the environment. The potential exposure pathways are described below.
2.2.2.1 Direct Radiation Exposure
Direct radiation exposure may occur if there are sufficient quantities of one or more radionuclides capable of delivering an external exposure both close enough to a human receptor and without sufficient shielding. Direct exposure is a concern during remediation efforts. Sources of external exposure after remediation may include elements not removed during remediation and from soil contamination. Radiation that is energetic enough to be an external concern is still not capable of activating other materials or causing contamination. Thus, there are no transport mechanisms to other media.
2.2.2.2 Air
Airborne contamination is a pathway that could pose a potential exposure risk to a worker or member of the public during remediation. Methods employed to decontaminate equipment and building surfaces may result in concentrations of airborne radioactive contamination within the BGRR facility. The transport of contaminants from the BGRR facility to the atmosphere could occur by means of fugitive dust emissions and vapor transport. The exposure pathway is the inhalation of airborne contaminants.
Soil contaminated with radium (Ra-226) may lead to exposure from radon (Rn-222). Radon is a gas that may be released from soil. However, unless there is a closed structure, radon and its daughters can not become concentrated and pose a potential hazard.
2.2.2.3 Surface Soil
Contamination of surface soil can occur through the deposition of airborne contamination and surface spills. Subsurface contamination has occurred from underground piping and ducts. During remediation, the failure of the HEPA filters may allow airborne contamination within the BGRR facility to be released and deposited on the ground. Human intrusion, such as digging a well, may bring contaminated material to the surface after remediation. The exposure pathways for surface soil are inhalation of fugitive dust, ingestion of soil and biota (see Subsection 2.2), and direct contact with soil contaminants. External exposure from radionuclides in soil was also discussed in Subsection 2.2. Hazardous substances in surface soil can be transported through the vadose zone and leached into groundwater.
2.2.2.4 Vadose Zone
One of the primary mechanisms for contaminant transport is vertical contaminant migration downward to the groundwater. Contaminants generally move as a dissolved phase in water, and their rates of migration are controlled both by water migration rates and by adsorption and desorption reactions involving the surrounding soils. Some contaminants are strongly sorbed on soils, and their downward movement through the stratigraphic column is greatly retarded. The equilibrium distribution coefficient, Kd, is the amount of radionuclide sorbed on sediment divided by the amount of radionuclide left in solution. It is a measure of the transport of radionuclides through porous geology. Radionuclides with low values of Kd are more easily transported.
Table 2-1 lists the equilibrium distribution coefficients (Kd) for several radioisotopes of concern as reported in the PFS Sampling and Analysis Plan (SAP) (BNL, 1999m). As seen from the table, there are both contaminants that tend not to leach, such as cesium and plutonium, as well as contaminants that may readily be transported to groundwater, such as strontium and radium. Groundwater in the Upper Glacial aquifer generally exists in unconfined conditions. This will allow contaminants in the vadose zone to leach to groundwater.
Exposure pathways from the vadose zone include direct external exposure and inhalation of radon gas. After remediation, the potential for vadose zone migration of contaminants could result from compromising engineering barriers of contaminated elements left after remediation.
2.2.2.5 Groundwater
Humans (workers and the public) can be exposed to groundwater contaminants either from groundwater obtained from wells or surface water. Exposure pathways include ingestion of water and biota (see Subsection 2.2), direct contact through bathing, and inhalation of radon gas.
During remediation, these contaminant pathways will not be of concern. After remediation and during the period of active institutional control, (50 years) the use of groundwater in the BGRR Area may be restricted. After the period of institutional control of the BGRR facility and areas downgradient of the BGRR facility, the groundwater may be a source of these exposures. However, while models have been used to predict groundwater flow and transport at BNL, modeling can not predict exact concentrations in groundwater downgradient of the BGRR due to the assumptions and simplifications inherent in groundwater models as stated in the Operable Unit III Remedial Investigation (IT, 1999).
2.2.2.6 Biota
Uptake of hazardous substances from air, surface soil, vadose zone, and groundwater by biota can result in the transport of contaminants through the food chain and eventually to humans. A farm scenario may lead to ingestion by animals. For example, while grazing, domestic animals and wildlife can ingest soil or plants containing hazardous substances. Surface water may directly impact biota subsequently consumed by human receptors. Human ingestion of soil and groundwater was discussed in Subsections 2.2.2.3 and 2.2.2.5 respectively. Biota can also receive external radiation exposure. However, as mentioned previously, the effects of external sources of radiation can not induce radioactivity (in biota). Consequently, there is no transport mechanism to a human receptor through external exposure of the biota.
After remediation, exposure to biota in the BGRR Area could occur if compromised engineering barriers exposed contamination. Plant pathways include irrigation of crops and root uptake from soil. Animal pathways include plant ingestion, groundwater ingestion, and soil ingestion. However, the limited available habitat around the BGRR would minimize the pathways to non-domestic terrestrial wildlife.
2.3 CONTAMINANTS OF POTENTIAL CONCERN
In the context of this report, contaminants of potential concern (COPCs) are the contaminants present that may have to be addressed by decommissioning actions. As mentioned in the Pile Fan Sump/Above-Ground Duct and Balance of Plant (BOP) Sampling and Analysis Plans (SAPs) (BNL, 1999k and BNL, 1999m), COPCs are not fully defined at this point. Consequently, actual contaminants of concern (COC) for the BGRR will be identified in future CERCLA documentation since a significant amount of quantitative radiological data is not available at the present time.
COPCs are those contaminants associated with the previous operation of the BGRR. Because either no data or limited data are available regarding contaminant concentrations, the historical and operational data, and process knowledge are the major sources of COPCs for this facility. Potential COPCs which may remain within the BGRR include:
In addition to COPCs within the BGRR and associated systems, there were a number of known or suspected spills outside the confines of the facility resulting in surface and possibly subsurface contamination near the facility. These included leakage from the fuel canal (sub-AOC 9A), water in-leakage and subsequent out-leakage from the underground air cooling ducts (sub-AOC 9B), spill sites in the west yard and in the east yard around the Canal House and Water Treatment Facility (sub-AOC 9C), and the pile fan sump for the air cooling discharge system (sub-AOC 9D). Detailed information is not available regarding the complete identification and concentration of contaminants associated with these spill areas.
There are several sources of radiological COPCs associated with prior operation of the BGRR: 1) the formerly used uranium fuel and associated fission and activation products; 2) historic activation of the reactor pile and structural material and equipment within and around the reactor pile; 3) historic activation of experiments introduced to the reactor pile; and 4) entrained particulate material.
2.3.1 Uranium Fuel & Daughters, Fission & Activation Products
Although the fuel has been removed from the reactor pile and the storage canal and shipped offsite, fuel residues, its radioactive decay progeny, and fission and activation products remain in the reactor and associated systems. Originally, the BGRR fuel consisted of natural uranium metal slugs in aluminum tubes. This fuel had a tendency to fail, which resulted in the gross release of fission and activation products within the fuel channels and reactor pile. In 1958, the BGRR was retrofitted with enriched uranium fuel, replacing the natural uranium metal fuel altogether. The new fuel elements were stable and did not fail with the exception of one or two occasions when the fuel plates overheated due to channel blockage (B&R, 1989).
Both types of fuel also released contamination as a result of leaks in fuel element cladding or through fission and activation of trace amounts of uranium contamination on the outer surfaces of the elements. Larger amounts were released when actual breaks in the tube, can, or cladding occurred.
Contamination due to these fission and activation products was transported from the fuel channels into the primary air cooling system, where it was deposited in the plenums, underground ducts, exhaust air filters, and even downstream of the filters in the above ground ducts, fans, and stack. The exhaust air filters were designed to be 95% efficient for particulate matter, which resulted in downstream contamination during the 18 years of BGRR operation.
During routine operation, penetrations in the biological shield may also have been contaminated with these fission and activation products including fuel charging tubes, experimental holes, and control rod drive mechanisms. Since these penetrations are generally lined with steel, the biological shield has been protected from contamination via these avenues; however, the linings are likely contaminated.
When the BGRR was operating, spent fuel was removed from the reactor pile via the south plenum fuel chute, moved into the deep pit, and subsequently into the canal. Contamination on the fuel cladding was spread to these areas.
Over 2,414 spent fuel elements, generated in an 18-year period, were shipped from the canal. The contaminated water, filter media, and back flushing from the ion exchange columns were pumped to the storage tanks at the Waste Concentration Facility, Building 811.
Numerous radioactive isotopes exist of uranium fuel, its decay progeny, fission products and activation products. The half-lives of these radioisotopes vary from very short to very long. Since it has been over 31 years since the BGRR was shut down (June 1968), any isotope with a half-life of two years or less will have undergone over 15 half-lives. This would result in a reduction in the activity of these isotopes by a factor of approximately 50,000. Although trace amounts of these radioisotopes may still be present, their concentrations will be negligible compared to the longer-lived radioisotopes. Table 2-2 shows radioisotopes with half-lives greater than two years that are thermal neutron fission products, of Uranium-235 (U-235) or Pu-239 (GE, 1989). These isotopes must all be considered as COPCs. In addition, some of them have radioactive decay progeny that are also radioactive and must also be considered as COPCs in isolated areas of the facility.
Table 2-3 presents the transuranic radionuclides with half-lives greater than one year resulting from nuclear activation of U-235 and U-238 in fuel elements. These isotopes must all be considered as COPCs. In addition, some of them have radioactive decay progeny that are also radioactive and must also be considered as COPCs.
The radioisotopes that comprise uranium fuel are U-234, U-235 and U-238. U-236 is a neutron activation product of U-235 but is also present in fuel that has been manufactured from recycled uranium. These uranium radioisotopes must be considered as COPCs. All of these radioisotopes decay into a series of progeny that are also radioactive. However, only the immediate progeny will have an activity concentration similar to that of the parent and must be considered as COPCs. Other progeny will be present in much smaller concentrations and are considered negligible in comparison. The relationship between uranium radioisotopes and their decay progeny is shown in Table 2-4.
2.3.2 Activation of Reactor Pile and Structural Material & Equipment
Within
and Around Reactor Pile
In addition to graphite, construction of the reactor pile included substantial amounts of structural material, shielding, operational equipment, experimental equipment, monitoring devices, and cooling structures. This material was subject to activation from the high neutron flux associated with operation of the BGRR.
The biological shield surrounding the reactor pile contains steel reinforcing rods, steel punchings, and limonite ore. The inner side of the shield is covered with six inches of steel. A twelve-inch steel belt surrounds the gap in the core. The core is also surrounded by an airtight steel membrane. Various experimental and operating apparatus may remain in Building 701, in and around the reactor pile. With the exception of the biological shield, most of these components are constructed of various types of steel and other metals. The pneumatic tubes are constructed of aluminum, plastic, and copper.
Table 2-5 shows possible neutron activation products of air and reactor pile materials. Graphite contains trace amounts of beryllium (Be), copper (Cu), samarium (Sm), silicon (Si), sulfur (S), deuterium (D or H-2), silver (Ag), iron (Fe), chlorine (Cl) that may become activated. Steel may contain iron (Fe-55), cobalt (Co-60), nickel (Ni-59, Ni-63), and molybdenum (Mo-93) as activation products. Concrete may contain calcium (Ca-41) as an activation product. All of these radioisotopes are plausible activation products for the BGRR and should be considered as COPCs. Gaseous activation products are not likely to have been retained in the BGRR.
2.3.3 Activation Of Experiments Introduced To The Reactor Pile
Throughout its 18 years of operation, a number of different experiments were introduced into the reactor pile for activation. Various activated experiments or production radioisotopes may remain in the graphite, plenums, exhaust duct heels, or between the beams under the reactor pile. After the new type of fuel was loaded, one of the functions of the BGRR was to produce Co-60 sources. Some of the sources were dropped or otherwise misplaced and therefore remain in the reactor pile. However, the majority of the sources were processed through the deep pit and canal for off-site shipment. Possible activation products for experiments with half-lives greater than two years are the same as those for reactor pile materials and are shown in Table 2-5 as COPCs.
2.3.4 Activation Of Cooling Air And Entrained Particulate Material
Table 2-5 shows possible neutron activation products of air including C-14, chlorine (Cl-36), argon (Ar-39 and Ar-42), and krypton (Kr-81) as gaseous activation products. However, with the exception of C-14 they are relatively inert gases which would have passed through the air cooling system and exited the stack. The intake air system included roughing filters that would have removed much of the entrained particulate matter before it could be activated in the reactor pile. Particulate matter that entered the reactor pile would likely result in the activation products previously shown in Table 2-5.
2.3.5 Radioactive Material In Bldg. 701 Nuclear Material Storage Vault
Building 701âs Nuclear Material Storage Vault is a segmented and separate facility. The information in Table 2-6 represents the current inventory of the vault. This does not include materials present that are packaged in Department of Transportation (DOT) Type B containers or special forms (i.e., sealed sources) maintained as such.
Plans are underway to relocate the entire inventory of nuclear material from Building 701âs Nuclear Material Storage Vault to other accountable storage locations onsite or to transfer it offsite as waste for final disposition. This action is scheduled to be completed before any significant decommissioning work begins within Building 701 (BNL, 1999f).
2.3.6 BGRR Inventory
Subsections 2.3.1 though 2.3.5 above identify radiological COPCs that are likely to exist in the reactor pile. However, these sections do not attempt to quantify the amount of these contaminants or discuss the relative amounts of the different contaminants. The amount of each COPC present in the BGRR depends on a complex relationship between its manner of production, the mass lost in the system, the mass of material available for activation, and the half-life of the radioisotope. The absolute and relative amount of most COPCs and their progeny will continue to change over time because of their different half-lives.
A conservative bounding estimate was made for the BGRR Balance-of-Plant (BOP) radiological inventory (BNL, 1999f). This estimate was developed from the calculated burn-up of the maximum number of natural uranium fuel slugs that are unaccounted. A balance of 14.62 kilograms (Kg, approximately 12.5 slugs) are unaccounted for as shown in Table 2-7 (BNL, 1999f). While portions of the inventory were released to the air cooling system as airborne material, the entire inventory is assumed to be present as BOP material for the sake of conservatism. No BGRR enriched uranium fuel was considered as adding to the inventory because it was not cut, lost, nor dispersed in the BGRR canal.
The BGRR natural uranium fuel-cycle and burn-up estimates of mixed fission products, and uranium fuel, activation, and progeny were calculated based on a conservative model (BNL, 1999f). The calculated BOP inventory is shown in Table 2-8.
With all fuel elements removed and all fuel channels rodded to remove any slugs, a rough bounding estimate was made of the total activity remaining in the BGRR reactor pile (BNL, 1999f). Activation of the graphite was estimated at 2.5E-06 Ci/g for Type A graphite, and 2.0E-06 Ci/g for Type B graphite, combined gamma and beta activities. The principal gamma activation contaminant for Type A graphite comes from Co-60, Eu-154, and Ag-108m. Type B gamma activation is primarily from Co-60 and Eu-154. Beta activation contamination for both types is due to C-14 and H-3. These results assumed the BGRR was running at full power 100% of the time for its 18-years of operation. The actual operating history included periods when the BGRR was not operating at full power or during scheduled shutdowns, so these estimates are very conservative.
The final COPC list, shown in Table 2-9, has been submitted to the regulators for review as part of the pile fan sump SAP (BNL, 1999m). These COPCs will be confirmed at the end of the review stage.
2.3.7 Non-Radiological Contaminants of Concern
At present, no specific quantitative data are available for the non-radionuclide potential inorganic and organic contaminants of concern. However, there is a sampling and analysis program presently in progress for the pile fan sump, process piping, above ground ductwork, and associated soils. At this point, the sludge located in the pile fan sump is believed to contain the "worst-case" concentrations of heavy metals (Hg, Cd, etc.). Heavy organics, such as PCBs, would also be likely to concentrate in the sludge. Chemical analysis of the pile fan sump sludge is currently being performed. The pile fan sump SAP (BNL, 1999m) states that until these data are available, the regulators concur that the non-radionuclide COPCs will be based on the compounds published in the inorganic and organic Contract Laboratory Program (CLP).
Non-radiological contamination at the site is likely the result of historical practices (mercury-containing instruments, PCB or lead-based paint, leaded solder joints, etc.), residual process chemicals (experimental tubes, mechanical systems, etc.), housekeeping (spills, leaks, etc.), and building materials (asbestos, etc.).
Though the full extent of non-radiological contamination can not be determined until characterization sample results are received, the potential for non-radiological contamination of some of the areas presently under investigation has been considered. The potential non-radiological contaminants of concern were outlined in the pile fan sump SAP (BNL, 1999m) and the WBS. These areas are:
Further sampling/confirmation will be required prior to removal activities in order to fully assess the effort and financial requirements of decommissioning the BGRR.
2.4 POTENTIAL APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS, and TO BE CONSIDERED REQUIREMENTS
The National Contingency Plan (NCP), 40 CFR 300, and Section 121(d) of CERCLA, as amended by SARA, require that primary consideration be given to alternatives implemented at a federal facility that attain or exceed promulgated Federal and State applicable or relevant and appropriate requirements (ARARs) to the extent practicable, or that a waiver of an ARAR is obtained. State requirements must be attained under Section 121 of SARA, if they are legally enforceable and consistently applied statewide. The EPA has indicated that ARARs must be identified for each site on the National Priority List (NPL).
This section presents a preliminary determination of the potential ARARs for the BGRR Decommissioning Project/removal action. This removal action will meet the ARARs referenced below and discussed further in Subsection 4.1.2 and Appendix D to the fullest extent practicable. This section also presents an identification of federal, state, and local non-enforceable criteria, advisories, and guidance that could be used for evaluating alternatives, defined as To Be Considered (TBC) requirements.
"For the purposes of identification and notification of promulgated state standards, the term promulgated means that the standards are of general applicability and are legally enforceable" (NCP, 300.400(g)(4)). The most stringent promulgated standards are applied as ARARs (Preamble to the NCP, 55 FR 8741, 8 March 1990).
Applicable requirements, as defined in 40 CFR 300.5, are those clean-up standards, standards of control, and other substantive requirements, criteria, or limitations promulgated under federal environmental or state environmental or facility siting laws that specifically address a hazardous substance, pollutant, contaminant, remedial action, location, or other circumstance found at a CERCLA site. Only those state standards that are identified by a state in a timely manner and that are more stringent than federal requirements may be applicable.
Actions must comply with state ARARs that are more stringent than the corresponding federal ARARs. State ARARs are also used in the absence of a federal ARAR, or where a state ARAR is broader in scope than the federal ARAR.
Relevant and appropriate requirements, also defined in 40 CFR 300.5, are those clean-up standards, standards of control, and other substantive requirements, criteria, or limitations promulgated under federal environmental or state environmental or facility siting laws, that, while not 'applicable' to a hazardous substance, pollutant, contaminant, remedial action, location, or other circumstance at a CERCLA site, address problems or situations sufficiently similar to those encountered at the CERCLA site that their use is well suited to the particular site. Only those state standards that are identified in a timely manner and are more stringent than federal requirements may be relevant and appropriate.
Relevant and appropriate requirements are intended to have the same weight as applicable requirements.
As defined in 40 CFR 300.400(g)(3), the TBC category "consists of advisories, criteria, or guidance developed by the U.S. Environmental Protection Agency, other federal agencies, or states that may be useful in developing CERCLA remedies." Use of TBCs is discretionary rather than mandatory, as opposed to the use of ARARs, which is mandatory. TBCs are not promulgated regulatory standards or requirements, and, therefore, are not under the definition of ARARs.
The ARARs Tables, shown in Appendix D, present a complete listing of the identified potential ARARs and TBCs for the BGRR Decommissioning Project, as well as their primary requirements and a preliminary determination of their applicability to the project. There are numerous ARARs related to groundwater quality shown in the tables that are noted to be "Not Applicable." The BGRR decommissioning should indirectly benefit groundwater quality beneath the site by removing soils that represent a potential source of contamination to groundwater. However, currently groundwater is not addressed under this Removal Action. Therefore, these regulations have been determined to not be applicable for the present project. These regulations may in fact be applicable in the future if groundwater remediation is conducted at the BGRR site as part of a separate action. For a similar reason, regulations pertaining to effluent discharge limits may be applicable in the future if groundwater treatment with discharge to the Peconic River or a Privately-Owned Treatment Works (POTW) is implemented at the BGRR site as part of a separate action.
Some ARARs may only apply in certain cases, such as if asbestos-containing building materials are encountered and must be removed as part of various alternatives (Federal asbestos regulations), or if specific temporary, on-site treatment processes are employed, such as air treatment and off gassing (Federal and State stationary emission source regulations). Therefore, these such regulations have been identified as only "Potentially Applicable." Other regulations pertain to discharge or other permits in effect at off-site waste disposal facilities that will receive, treat, and/or dispose of wastes generated during the decommissioning project. These regulations have been considered TBCs. The selection process for off-site disposal facilities will ensure that wastes are disposed at appropriately licensed and permitted facilities. However, these regulations do not apply directly to the BGRR project site, and therefore are TBCs.
2.4.1 ARAR Categories
In general, there are three categories of ARARs:
A description of these three categories and the preliminary chemical-specific, location-specific and action-specific ARARs for the BGRR site are discussed in the following subsections.
2.4.2 Chemical-Specific ARARs
Chemical-specific ARARs are usually health- or risk-based numerical values used to establish the acceptable limits of a chemical or radiological contaminant that may be found in, or discharged to, various environmental media. Chemical-specific ARARs are based on human health, ecological risks, and exposure pathways. The ARARs may influence the selection of the removal alternative by setting objectives that the alternative must meet to reduce risks to health and the environment. If a chemical or radiological contaminant has more than one such requirement that is an ARAR, the most stringent generally should be applied.
A summary of potential chemical-specific ARARs for the contaminants at the BGRR site is presented in the Tables D-1 and D-4. The health-based, chemical-specific ARARs are primarily derived from federal and state health and environmental statutes and regulations. As discussed below and in the referenced tables, in some instances these standards are classified as items "To Be Considered". Table D-1 presents the potential federal chemical-specific ARARs that are applicable to the BGRR site, and Table D-4 presents the potential State of New York chemical-specific ARARs.
2.4.3 Location-Specific ARARs
Location-specific ARARs are statutes or regulations which set restrictions on the concentration of hazardous substances or the conduct of activities solely because they are in specific locations. Some examples of special locations include floodplains, wetlands, and sensitive ecosystems or habitats. The potential location-specific ARARs are presented in Table D-2 (potential federal ARARs), and Table D-5 (potential State of New York ARARs).
2.4.4 Action-Specific ARARs
Action-specific ARARs are usually technology- or activity-based requirements or limitations on actions taken with respect to the various removal alternatives. Performance, design, and other action-specific requirements set controls or restrictions on particular kinds of activities related to management of hazardous or radiological contaminants. These requirements are triggered by the particular remediation activities that are selected to accomplish a remedy. Very different requirements can come into play depending on these activities. These action-specific requirements do not in themselves define the removal alternative; rather, they indicate how a selected alternative must be achieved.
Potential action-specific ARARs are the Resource Conservation and Recovery Act (RCRA) standards for transport and disposal of hazardous materials. The potential action-specific ARARs for the BGRR Decommissioning Project are presented in Table D-3 (potential federal ARARs), and Table D-6 (potential State of New York and local (Suffolk County Department of Health Services [SCDHS]) ARARs.
2.4.5 To Be Considered (TBC) Requirements
TBCs consist of non-enforceable advisories, criteria, or guidance developed by federal, state, or local agencies that may be useful in developing CERCLA remedies. TBCs are not promulgated regulatory standards or requirements, and, therefore, are not under the definition of ARARs. Potential TBCs are included in Tables D-1 through D-6.
The following important TBC guidance will be considered as part of the BGRR Decommissioning Project:
2.4.6 Identification And Evaluation Of ARARs
Development of a preliminary list of potential chemical-specific ARARs allows the establishment of a list of preliminary remediation goals (PRGs) in the decommissioning process, described in more detail in Subsection 2.6. The PRGs are essentially a tentative listing of contaminants together with initially anticipated clean-up concentrations or risk-based levels for each medium. PRGs serve to focus the development of alternatives on remedial technologies that can achieve the remediation goals, thereby limiting the number of alternatives to be considered in the detailed analysis conducted later in the removal alternatives analysis process.
At the beginning of the removal alternatives analysis process, a preliminary consideration of location- and action-specific ARARs is commonly conducted. As alternatives are screened, action-specific ARARs are identified. When the detailed analysis of the removal alternatives is conducted, all action-specific ARARs are refined to a much more detailed form with respect to each alternative. The ARARs will be finalized based on the review and recommendations of BNL, DOE, and other members participating in the IAG. These final ARARs (with some modification based on background levels) in conjunction with the risk based concentrations will be used to establish media-specific cleanup objectives for the BGRR site.
Once a preferred removal action alternative is formally selected, all chemical, location, and action-specific ARARs are identified. If it is found that the most suitable removal action alternative does not meet an ARAR, the NCP provides for waivers of ARARs under certain circumstances. According to 40 CFR 300.430(f)(1)(ii)(C).
An alternative that does not meet an ARAR under federal environmental or state environmental or facility siting laws may be selected under the following circumstances:
Accordingly, if any of the alternatives selected for the BGRR site are expected to not attain an ARAR, this expectation must be expressed together with an appropriate justification that relates to at least one of the ARAR waiver circumstances identified above. An evaluation of compliance of the various removal alternatives for the BGRR site with ARARs is presented in Table D-7 in Appendix D.
2.5 REMEDIAL ACTION OBJECTIVES
This section describes the elements used to develop the Remedial Action Objectives (RAOs), and presents the RAOs used to evaluate alternatives. RAOs are media-specific or operable unit-specific objectives for protecting human health and the environment. RAOs are developed considering land use, COPCs, potential ARARs, and exposure pathways (as in the conceptual model). Specific remediation goals are also identified so that an appropriate range of decommissioning options can be developed for evaluation.
The RAOs were evaluated by the BGRR project team with respect to public and stakeholder values. The RAO process begins by identifying potential future land use and the COPC for the BGRR facility. This information ensures that removal alternatives being considered can adequately address the types of contaminants present, and facilitate the refinement of potential ARARs. The RAOs also provide the basis for developing the general response actions that will satisfy the objectives of protecting human health and the environment. The RAOs are defined as specifically as possible without limiting the range of general response actions that can be applied.
The RAOs for decommissioning the BGRR facility are based on discussions previously presented in this report. The objectives reflect community and stakeholder values as discussed with the project team during roundtable meetings. The RAOs for the BGRR Decommissioning Project are stated below. The RAOs are not presented in any particular order.
2.6 PRELIMINARY REMEDIATION GOALS
Preliminary remediation goals (PRGs) have already been developed for several operable units (OUs) at BNL. PRGs for the BGRR will be similar to these other OUs if factors such as land use, exposure pathways, contaminated soil zone parameters, hydrology data and external gamma parameters are comparable. The Sampling and Analysis Program for the Disposal of Debris from Decommissioning Activities at the BGRR Reactor Complex (BNL, 1999k) summarized PRGs from those developed for these other OUs as well as lists the PRGs developed for that document. These have been submitted to the regulatory agencies for review. The PRGs listed in this document have not yet been approved for BGRR decommissioning activities.
2.6.1 Radiological Constituents in Soils and Groundwater
As stated in the Record of Decision (ROD) for Operable Unit I and Radiologically Contaminated Soils (BNL, 1999g), the cleanup goal for radionuclides is based on a total dose limit of 15 mrem/yr above background. Soil PRGs are calculated using the DOE Residual Radioactive Material Guidelines (RESRAD) computer code or are based on regulatory documents. Fifty (50) years of institutional control were assumed when running the RESRAD code and this time period is critical when developing PRGs for radionuclides with half lives less than this 50 year time period. Contaminants such as Cs-137, Sr-90, Co-60, and H-3 (tritium), will all decay to less than half their present day concentration during this period of control. The choice of residential or industrial land use also influences the soil PRGs. The potential for contamination in soil to leach into groundwater is also considered to be more significant for those radionuclides including strontium, radium and uranium with low Kd values (See Figure 2-1). Cleanup goals for Ra-226 are based on DOE Order 5400.5 (DOE, 1993). The OUI ROD lists the cleanup goals for Cs-137 and Sr-90. PRGs for other radionuclides should be similar to those listed in the pile fan sump SAP (BNL, 1999m). Table 2-10 summarizes the radionuclide PRGs. These values have not yet been approved for the BGRR Decommissioning Project.
Final DCGLs may reflect these preliminary dose-based goals, they may be risk-based (pending results of additional characterization or full risk analysis), or they may be a combination of both dose-based preliminary goals and risk-based goals.
2.6.2 Radiological Constituents for the BGRR Facility
It is anticipated that the ongoing characterization effort will address data gaps in this area. However, based on the expected mix of radionuclides and yearly allowable dose release criteria, surface contamination concentration guidelines may be derived. Values for the release of building surfaces exist in DOE Order 5400.5 (DOE, 1993). However, DOE, EPA and Nuclear Regulatory Commission (NRC) accept the decommissioning strategies in the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM, NUREG 1997) and site-specific values may be generated. Computer codes that can be utilized to calculate realistic site-specific surface contamination release levels include the DOEâs RESRAD-Build and the NRCâs Decontamination and Decommissioning (D & D) code. One or more of these codes (or other codes) is applied to the appropriate scenarios with the dose limit of 15 mrem per year that has already been determined for this project. Establishment of total and removable surface contamination release levels in disintegrations per minute (dpm)/100 cm2 will be important for alternatives that leave buildings, equipment, or other structures in place.
The use of very conservative assumptions may result in unwarranted costs or inefficient remediation requirements. For this reason, site-specific parameters have been developed and are to be used instead of generic default parameters in these codes. This provides realistic dose estimates instead of over-estimating potential dose. Exposure scenarios based on site-specific parameters include the extent of potential future exposure to residual radioactivity.
2.6.3 Non Radiological Constituents
PRGs for nonradiological constituents in soils, groundwater, and BGRR facility structures and equipment are discussed below. The primary focus of removal actions is on the radiological constituents of concern. Considering the history of the BGRR (discussed in detail in Section 1), any nonradiological constituents of concern, if present, would be expected to be more localized in distribution and found in smaller volumes than the radiological constituents. The nonradiological constituents will be addressed and remediated in conjunction with the radiological constituents, due to their anticipated smaller volumes and close association with radiologically contamination at the BGRR facility.
2.6.3.1 Soils and Groundwater
Preliminary remediation goals for nonradiological COCs in soils developed previously for other OUs at BNL may be applied at the BGRR site. For example, a PRG was calculated for mercury in soils as part of the Chemical/Animal Pits and Glass Holes project. The development of this PRG is summarized in Appendix E of the Final Feasibility Study Report Operable Unit I and Radiologically-Contaminated Soils (CDM, 1999). These PRGs have been developed based on background levels in soils at BNL, NYSDEC soil cleanup objectives (TAGM #4046, Determination of Soil Remediation Objectives and Remediation Levels, January 1994), and other federal soils cleanup guidance. The specific nonradiological constituents involved will be determined as decommissioning work proceeds. Soils PRGs are generally set at levels that are protective of groundwater. Groundwater is not the objective of BGRR removal actions. Groundwater PRGs may be determined at a future date as part of potential groundwater remediation activities handled under a separate phase of the BNL Environmental Restoration Project.
2.6.3.2 BGRR Facility Structures and Equipment
Other constituents may exist in or on (such as painted surfaces) BGRR facility structures or equipment that will be dismantled and removed, including lead, asbestos, mercury, etc. These constituents will be characterized, removed, and disposed and/or treated at appropriately licensed and permitted off-site waste disposal facilities in conjunction with removal of the structures or equipment. For this reason, the application of PRGs is not directly appropriate. Instead, all of the constituents associated with structures or equipment to be removed will also be removed and disposed of properly. The applicable requirements to be followed include the requirements of RCRA, OSHA, Toxic Substance Control Act (TSCA), and pertinent State regulations.
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