Radionuclides Of Concern Research Articles

Nuclear Waste Management: A Mini Review on Waste Package Characterization Approaches

The characterization of nuclear wastes is the first step toward their efficient management, as the efficient identification of the chemical, physical, biological, mechanical, and/or radiological properties of these materials is crucial to optimize their management scheme. In particular, the radiological characterization of the nuclear waste packages is challenged by many factors that require the identification of integrated characterization schemes that rely on the use of both conventional and innovative techniques. In this work, the strategies and approaches adopted for nuclear waste characterization are discussed with special reference to innovative characterization techniques with respect to waste packages. In this regard, both nondestructive and destructive techniques that are conventionally used to analyze raw and processed nuclear waste packages are overviewed. The separation methods that are implemented to identify most of the radionuclides of concern are given, where the radiometric methods are outlined for those radionuclides. The implementation of scaling factor methodology to ensure reliable characterization will be highlighted.

Gamma Radioactivity Detection Limits and Associated Radionuclide Intakes Study in Artificial Human Urine Using Sodium-iodide and High-purity Germanium Detectors.

The performance of several gamma detectors was investigated for emergency urine bioassay screening of two radionuclides of concern: 131 I and 137 Cs. Unspiked artificial urine samples were measured for 10 min each on four different gamma detectors: 80% relative efficiency high-purity Ge detector in standard shielding, 102% low-background high-purity Ge detector equipped with top muon shield, 78% high-purity Ge well detector in standard shielding, and 4″ × 4″ NaI well detector in standard shielding. The measured gamma spectra were analyzed in two ways: (1) for the 364-keV peak region of 131 I and 662-keV peak region of 137 Cs and (2) for the total counts in the full energy spectrum (50-2,048 keV). The results were analyzed using the principles of signal detection theory according to the Currie's formalism extended by a complete uncertainty propagation. This enabled calculation of the detection capability in terms of detection limit (Bq L -1 ) of urine, the latter referred to as minimum detectable activity. The NaI well detector had the lowest minimum detectable activities for total spectra, whereas the high-purity Ge well detector had the lowest peak minimum detectable activity values. Minimum detectable inhalation and ingestion intakes from urine bioassay were calculated from the minimum detectable activity values for urine collection 1 d, 1 wk, and 1 mo past the initial intake. The calculated intakes were compared with annual limits on intake. The results are interpreted with respect to a large-scale radiological emergency response.

Modeling: Activity Concentration of Radon, Thoron, and Their Decay Products in Closed Systems

The article presents a model for simulating changes in the activity concentration of radon and thoron as well as their progeny in closed or poorly ventilated systems. A system can be considered closed when a stream of radon and thoron flows into a space, but nothing comes out. It was also assumed that there may be devices or installations with a filtering system that would reduce the concentration of radon and thoron decay products. These assumptions may, therefore, correspond to a situation in which, in an isolated chamber, the calibration of radon hazard-monitoring devices is carried out, and nuclides are supplied from an emanation or flow through sources or well-isolated spaces in an environment where the source of nuclides is, for example, radon and thoron exhalation. The differential equations were formulated on the basis of the assumption that the activity concentration of radionuclides of concern in the space is uniform. The equations do not consider possible losses due to diffusion or the inertial or gravitational deposition of aerosols. If these phenomena have a limited impact on changes in the activity concentration of nuclides, the solutions provided may be used to simulate the activity concentration of radon and thoron and their decay products in any confined space assuming different boundary conditions.

A Critical Review of the Removal of Radionuclides from Wastewater Employing Activated Carbon as an Adsorbent.

Radionuclide-contaminated water is carcinogenic and poses numerous severe health risks and environmental dangers. The activated carbon (AC)-based adsorption technique has great potential for treating radionuclide-contaminated water due to its simple design, high efficiency, wide pH range, quickness, low cost and environmental friendliness. This critical review first provides a brief overview of the concerned radionuclides with their associated health hazards as well as different removal techniques and their efficacy of removing them. Following this overview, this study summarizes the surface characteristics and adsorption capabilities of AC derived from different biomass precursors. It compares the adsorption performance of AC to other adsorbents, such as zeolite, graphene, carbon nano-tubes and metal-organic frameworks. Furthermore, this study highlights the different factors that influence the physical characteristics of AC and adsorption capacity, including contact time, solution pH, initial concentration of radionuclides, the initial dosage of the adsorbent, and adsorption temperature. The theoretical models of adsorption isotherm and kinetics, along with their fitting parameter values for AC/radionuclide pairs, are also reviewed. Finally, the modification procedures of pristine AC, factors determining AC characteristics and the impact of modifying agents on the adsorption ability of AC are elucidated in this study; therefore, further research and development can be promoted for designing a highly efficient and practical adsorption-based radionuclide removal system.

Binding mechanism of strontium to biopolymer hydrogel composite materials

Strontium-90 is a radionuclide of concern that is mobile in soil and groundwater and is a threat to life. Activated hydrogel biopolymer composites were fabricated for strontium remediation from groundwater. Batch uptake demonstrated a maximal stontium uptake capacity of 109 mg g−1, much higher than unactivated hydrogel controls. Activation also more than doubled the decontamination factor at environmentally relevant concentrations. EXAFS was used to investigate the binding mechanism, revealing inner sphere complexation of strontium for the first time. Biopolymer composities synthesized for these studies are sustainable and cheap remediation materials that exhibit good strontium uptake and inner sphere binding.

Quantification of a Facility Radiological Security Risk Index With a Graphical User Interface Tool.

Healthcare facilities around the world routinely use radioactive sources to diagnose and treat illness. To effectively manage the security of radioactive sources, these facilities need to understand the risk, which is comprised of threat, vulnerability, and consequences. The threat component of risk requires knowledge of potential adversaries and understanding their capabilities and intentions. To help articulate the multiple layers of threat and support better informed decisions, the research developed a risk-based methodology to evaluate radiological security at the facility level. The methodology is applied to a radiological dispersal device (RDD) incident from three radionuclides of concern: 137Cs, 60Co, and 192Ir. The results of the research have led to the creation of a potential facility risk index (PFRI). The PFRI is mathematically represented as the exponential product of the maximum expected utility among the threat groups, the sum of geographic vulnerability and cultural vulnerability, and net consequences. The PFRI is a novel risk index that quantifies the facility risk on a scale of 1 to 10, 1 being "very low risk" and 10 being "very high risk." A MATLAB-based graphical user interface (GUI) tool was also developed to enable the radiological facility (i.e., healthcare facility) staff to conduct self-assessments and manage their most valuable assets. The PFRI methodology is a useful starting point for any healthcare facility risk assessment and is a valuable input for decision makers considering potential investments in security upgrades.

Simultaneous total and speciation analysis of rhenium by capillary electrophoresis-inductively coupled plasma mass spectrometry

As one of the most concerned radionuclides, 99technetium (Tc) usually exists as pertechnetate (TcO4−) and low-valence Tc(IV) in the environment. The speciation analysis of 99Tc plays a crucial role in understanding its toxicity, bioavailability and mobility, and developing effective remediation strategies. However, conventional hyphenated techniques for 99Tc speciation analysis usually require a large sample volume and tedious operation process. In this work, a simple but highly effective system, coupling capillary electrophoresis to inductively coupled plasma mass spectrometry (CE-ICP-MS), was developed to analyze total rhenium (TRe), Re(IV), and Re(VII), known as the analogues of technetium. It is worth noting that by the use of a sprayer with a direct-injection nebulizer as the interface, the CE and ICP-MS were efficiently coupled as an entity that shares the advantages of both modules. In comparison to conventional techniques, the proposed CE-ICP-MS dominates in terms of less sample consumption and higher sample introduction efficiency, thus results in improved sensitivity, reduced radioactive waste, and more significantly, alleviated radiological exposure to operators. Under the optimized conditions, LODs of 0.02 μg L−1 and 0.01 μg L−1 were obtained for TRe and Re(VII), respectively, with relative standard deviations (RSDs) better than 3.0%. In addition, the accuracy and practicability of this hyphenated system were validated by analyzing simulated Hanford site groundwater samples with satisfactory recovery and separation of TRe, Re(IV), and Re(VII). The proposed method retains the great potential for the speciation analysis of 99Tc in various samples.

Rapid, competitive radium uptake in strontium, barium, and lead sulfates during sulfuric acid leaching

Uranium- and thorium-bearing base metal mineral deposits contain daughter radionuclides which must be monitored and preferably removed or reduced during the process of generating base metal sulfide concentrates. Understanding the behavior of these radionuclides (focusing on 226Ra in this study) is critical for minimizing their concentrations in final economic products. To this end, Ra uptake into Sr, Ba, and Pb sulfates was evaluated experimentally under various conditions, including those approximating processing plant environments. Lead activity was also monitored, as 210Pb is also a radionuclide of concern. To simplify experiments, synthetic crystals of celestine (SrSO4), baryte (BaSO4), and anglesite (PbSO4) were grown in silica gel and subsequently exposed to RaCl2 solution at both low and neutral pH, for both 40 and 210 h. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) transects were performed across the grains to determine uptake of Ra (as well as trace Sr, Ba, and Pb) in the sulfates. Results indicate that Ra uptake in celestine is efficient when Ba and Pb are absent but is reduced to nearly zero when competing with baryte and anglesite. High acid sulfate activity inhibits uptake. Baryte incorporates significant Ra under all conditions. Anglesite is affected by coupled dissolution-reprecipitation mechanisms, resulting in dissolution of PbSO4 followed by precipitation of a mixed (Pb,Ba,Sr,Ra)SO4 phase in its place. Again, high sulfate activity inhibits this reaction. With this knowledge, it may be possible for process engineers to purposefully stimulate precipitation of Ra (and possibly Pb) onto a sulfate matrix, given the right conditions. Precipitation of RaSO4 (and 210PbSO4) onto a removable phase during processing would result in sulfide concentrates with natural background concentrations of radionuclides. Results from this study, including semi-quantitative Ra concentration data obtained via in situ LA-ICP-MS analysis add to data pertinent to management of Ra in boiler scales, oil and gas pipelines, environmental remediation, nuclear medicine, nuclear fuel processing and waste storage, among other industrial and research applications.

Effects of sulfate on rhenium incorporation into low-activity waste glass

Technetium-99 (99Tc) is a major radionuclide of concern in the Hanford low-activity waste (LAW), which will be vitrified into borosilicate glass at the Waste Treatment and Immobilization Plant (WTP). Sulfate in LAW has been known to be a critical factor affecting the volatile loss of 99Tc. We investigated rhenium (a nonradioactive surrogate for 99Tc) incorporation by crucible melting tests of two representative simulated LAW glass feeds, each prepared with varied sulfur concentrations in glass. The slurry feeds were dried and heated to 400–1100 °C. Soluble and insoluble phases of heated feeds were analyzed to profile the partitioning of various components during the melting process. The mechanism of how sulfate affects rhenium incorporation during feed-to-glass conversion reactions, and so final retention of rhenium in glass, is proposed based on the two hypotheses that segregated sulfate-rich phase forms during feed conversion reactions and Re preferentially partitions to this sulfate-rich phase.

Effect of dose and dose rate on temporal \u03b3-H2AX kinetics in mouse blood and spleen mononuclear cells in vivo following Cesium-137 administration

BackgroundCesium-137 (137Cs) is one of the major and most clinically relevant radionuclides of concern in a radiological dispersal device, “dirty bomb” scenario as well as in nuclear accidents and detonations. In this exposure scenario, a significant amount of soluble radionuclide(s) may be dispersed into the atmosphere as a component of fallout. The objectives of the present study were to investigate the effect of protracted 137Cs radionuclide exposures on DNA damage in mouse blood and spleen mononuclear cells (MNCs) in vivo using the γ-H2AX biomarker, and to develop a mathematical formalism for these processes.ResultsC57BL/6 mice were injected with a range of 137CsCl activities (5.74, 6.66, 7.65 and 9.28 MBq) to achieve total-body committed doses of ~ 4 Gy at Days 3, 5, 7, and 14. Close to 50% of 137Cs was excreted by day 5, leading to a slower rate of decay for the remaining time of the study; 137Cs excretion kinetics were independent of activity level within the tested range, and the absorbed radiation dose was determined by injected activity and time after injection. Measurements of γ-H2AX fluorescence in blood and spleen MNCs at each time point were used to develop a new biodosimetric mathematical formalism to estimate injected activity based on γ-H2AX fluorescence and time after injection. The formalism performed reasonably well on blood data at 2–5 days after injection: Pearson and Spearman’s correlation coefficients between actual and predicted activity values were 0.857 (p = 0.00659) and 0.929 (p = 0.00223), respectively.ConclusionsDespite the complicated nature of the studied biological system and the time-dependent changes in radiation dose and dose rate due to radionuclide excretion and other processes, we have used the γ-H2AX repair kinetics to develop a mathematical formalism, which can relatively accurately predict injected 137Cs activity 2–5 days after initial exposure. To determine the assay’s usefulness to predict retrospective absorbed dose for medical triage, further studies are required to validate the sensitivity and accuracy of the γ-H2AX response after protracted exposures.

Estimation of radon release rate for an underground uranium mine ventilation shaft in China and radon distribution characteristics

Radon, known to be a human carcinogen, is one of the most concerned radionuclides in uranium mining which need to be monitored and controlled. A large amount of radon is discharged to the atmosphere mainly through underground ventilation shafts for underground uranium mining. There are many studies on radon release of uranium mine, but the differences of the measured radon results are very big. In this paper, a typical underground uranium mine in China is chosen as a case study. This study finds that distribution of radon concentration and airflow speed inside the ventilation shaft are extremely uneven, but the distributions are respectively stable and regular for a fixed cross-section at the wellhead depth of 0–1 m. There is also a stable numerical relationship between the radon release rate and the product of radon concentration and airflow speed at the center for any cross-section in the shaft. Based on this regulation, a multipoint interpolation-integration method and a one-point method for calculating radon release from underground ventilation shaft are proposed in this paper. The results show that the difference between these two methods is 2–10%, the one-point method is more suitable and convenient to be applied for the long-term monitoring radon release rate from uranium mine ventilation. The research results in this paper can be applied in the estimation of radon release rate for other underground uranium ventilation shafts.

Impact of produced water discharge on the gross alpha and gross beta activity concentrations and radiological health risk on drinking water sources in coastal areas of Nigeria

ABSTRACT Gross alpha and gross beta activity concentrations in drinking water samples from coastal areas of Nigeria has been investigated using an MPC-2000-DP model proportional counter. A total of 60 drinking water representative samples (four each from communities’ drinking water sources) were collected from the study area. The mean gross alpha activity concentrations values obtained ranged from 0.02 ± 0.00 Bq l–1 to 1.37 ± 0.01 Bq l–1 with an average value of 0.38 ± 0.03 Bq l–1 while the mean gross beta activity concentrations values ranged from 0.41 ± 0.04 Bq l–1 to 7.32 ± 0.33 Bq l–1 with an average value of 2.96 ± 0.41 Bq l–1. These revealed that the gross alpha and gross beta activity levels obtained in the drinking water were above the recommended permissible limit of 0.1 and 1.0 Bq l–1, respectively, and that of the control values. The annual effective dose equivalent, annual gonadal equivalent dose, excess lifetime cancer risk and committee effective dose due to drinking of these drinking water sources by infants, children and adults from gross alpha activity concentration when compared with their world average standards, were found to be higher than the world allowable average values. These high values obtained were attributed to anthropogenic activities (oil and gas activities) in the study area. This anthropogenic activities of discharging produced water into water bodies of these 15 communities studied has contaminated the drinking water radiologically, which might pose significant radiation health threat to both human system and the environment. Further study on the specific activity to identify the radionuclide of concern was recommended.

Adsorptive removal of 134Cs+, 60Co2 + and 152 + 154Eu3 + radionuclides from aqueous solutions using sepiolite: Single and multi-component systems

Single and multi-component adsorptive removal of 134Cs+, 60Co2+ and 152+154Eu3+ from aqueous solutions onto sepiolite are studied in the present study. Removal of these radionuclides in single systems is found to be strongly dependent on the initial pH on the solution. Removals >99% (for 60Co2+ and 152+154Eu3+) and of about 82% (for 134Cs+) are achieved at initial pH values higher than 4 and 5, respectively. The kinetic data and the equilibrium isotherms are modeled by two kinetic models, the pseudo-first-order and the pseudo-second-order, and two isotherm models, Langmuir and Freundlich, respectively. The effect of various coexisting cations, Na+, Ca2+ and Al3+, at different concentrations on the adsorption processes of the concerned radionuclides in single systems was evaluated. Desorption studies of radionuclide-loaded sepiolite are studied using different concentrations of organic, EDTA and HA (strong complexing agents for radionuclides), and inorganic, HCl, NaCl, CaCl2, Mg(NO3)2 and AlCl3, desorbing agents. Adsorption mechanisms of radionuclides onto sepiolite are deeply discussed. Multi-component adsorptive removal of 134Cs+, 60Co2+ and 152+154Eu3+ onto sepiolite as a function of adsorbent weight and time was also studied. The influence of the solution pH on co-removal efficiency of radionuclides was investigated in presence of EDTA. Furthermore, the present investigation evaluated the removal efficiency of radionuclides, in multi-systems, in presence of different concentrations either of NaCl or CaCl2.

Natural radioelement concentrations in the soil of the Mila region of Algeria

In this study, the levels of the natural and artificial radioactivity in soil samples collected at various depths from Algerian agricultural region El-Athmania Mila was measured. Activity concentrations of the concerned radionuclides were determined by gamma-ray spectrometry using a high-purity germanium detector. The activity concentrations of 226 Ra, 232 Th and 40 K were found unchanged as a function of depth and ranged from 23.72±2.37to 65.47±5.06 Bq.kg−1 for 226 Ra, from 26.45±0.78 to 27.10±0.80 Bq.kg−1 for 232 Th and from 220.80±10.01 to 260.70±8.24 Bq.kg−1 for 40 K respectively. To evaluate the radiological hazard of radioactivity in samples, the radium equivalent activity (Raeq), the absorbed dose rate (D), the annual effective dose and the external (Hex) and internal hazard indices (Hin) were calculated. The mean of the excess lifetime cancer risk observed in this study are under the world's mean values.

Silver-based getters for 129I removal from low-activity waste

Abstract A prominent radionuclide of concern in nuclear wastes, 129I, is present in low-activity wastes (LAW) at the Hanford site. Several Ag-containing materials were tested as immobilization agents, or “getters”, for I (as iodide, I−) removal from deionized (DI) water and a liquid LAW simulant: Ag impregnated activate carbon (Ag–C), Ag exchanged zeolite (Ag–Z), and argentite. In anoxic batch experiments with DI water, the Ag–C and argentite were most effective, with maximum Kd values of 6.2 × 105 mL/g for the Ag–C and 3.7 × 105 mL/g for the argentite after 15 days. Surface area and Ag content were found to influence the performance of the getters in DI water. In the anoxic batch experiments with LAW simulant, Ag–Z vastly outperformed the other getters with Kd values of 2.2 × 104 mL/g at 2 h, which held steady until 15 days, compared with 1.8 × 103 mL/g reached at 15 days by the argentite. All getters were stable over long periods of time (i.e. 40 days) in DI water, while the Ag–Z and argentite were also stable in the LAW simulant. Ag–Z was found to have consistent I removal upon crushing to a smaller particle size and in the presence of O2, making it a strong candidate for the treatment of LAW containing I.

Measurements of cesium in Arctic beluga and caribou before and after the Fukushima accident of 2011

Concern from northern communities following the Fukushima Daiichi nuclear accident of March 2011 has prompted a reassessment of the safety of their traditional foods with respect to radioactivity levels. To this end, a study was conducted to measure the levels of radionuclides in Arctic caribou (Rangifer tarandus) and beluga (Delphinapterus leucas). The main radionuclide of concern is cesium-137, which is easily transferred through the lichen-caribou food chain. Previous studies have been conducted on the cesium-137 levels in Canadian caribou herds from 1958 to 2000, allowing researchers to determine the amount of cesium-137 in caribou specifically attributable to atmospheric weapons testing and the Chernobyl nuclear accident in 1986. In this study, samples of lichens, mushrooms, caribou, beluga and beluga prey collected before and after the Fukushima accident were analyzed for radioactivity levels. Samples were processed and measured using gamma ray spectroscopy to identify the radionuclides present and determine the radioactivity concentration. Both calibration standards and Monte Carlo simulations were used to determine the efficiency of the detectors for the samples, taking into account differences in individual sample sizes as well as matrices. In particular, a careful analysis of the atomic composition of lichens and mushrooms was performed to ensure the efficiencies for these sample types were correct. A comparison of the concentrations from before and after the accident indicated that there was no increase in radioactivity as a result of the atmospheric plume from the Fukushima accident. Some cesium-137, likely attributable to fallout from atmospheric weapons testing of the 1950s and 1960s (since there was no cesium-134 measured in the samples), was measured in the post Fukushima caribou and beluga whale samples; however, this amount was determined to be insignificant for any radiological concern (9.1 ± 1.8 and 0.63 ± 0.23 Bq kg−1 ww respectively). The activity concentrations of cesium-137 was about 200 times smaller than that of natural radioactive potassium in the beluga samples. Both the caribou and beluga results showed that these foods continue to be a healthy food choice for northern Canadians with respect to radioactivity, and this result has been communicated to the nearby northern communities and stakeholders.

From early prophylaxis to delayed treatment: Establishing the plutonium decorporation activity window of hydroxypyridinonate chelating agents

The potential consequences of a major radiological event are not only large-scale external radiation exposure of the population, but also uncontrolled dissemination of, and internal contamination with, radionuclides. When planning an emergency response to radiological and nuclear incidents, one must consider the need for not only post-exposure treatment for contaminated individuals, but also prophylactic measures to protect the workforce facing contaminated areas and patients in the aftermath of such events. In addition to meeting the desired criteria for post-exposure treatments such as safety, ease of administration, and broad-spectrum efficacy against multiple radionuclides and levels of challenge, ideal prophylactic countermeasures must include rapid onset; induce minimal to no performance-decrementing side effects; be compatible with current military Chemical, Biological, Radiological, Nuclear, and Explosive countermeasures; and require minimal logistical burdens. Hydroxypyridinone-based actinide decorporation agents have shown the most promise as decorporation strategies for various radionuclides of concern, including the actinides plutonium and americium. The studies presented here probe the extent of plutonium decorporation efficacy for two chelating agents, 3,4,3-LI(1,2-HOPO) and 5-LIO(Me-3,2-HOPO), from early pre-exposure time points to a delay of up to 7 days in parenteral or oral treatment administration, i.e., well beyond the initial hours of emergency response. Despite delayed treatment after a contamination event, both ligands clearly enhanced plutonium elimination through the investigated 7-day post-treatment period. In addition, a remarkable prophylactic efficacy was revealed for 3,4,3-LI(1,2-HOPO) with treatment as early as 48 h before the plutonium challenge. This work provides new perspectives in the indication and use of experimental actinide decorporation treatments.

Ultra-trace determination of 90Sr, 137Cs, 238Pu, 239Pu, and 240Pu by triple quadruple collision/reaction cell-ICP-MS/MS: Establishing a baseline for global fallout in Qatar soil and sediments

The development of practical, fast, and reliable methods for the ultra-trace determination of anthropogenic radionuclides 90Sr, 137Cs, 238Pu, 239Pu, and 240Pu by triple quadruple collision/reaction cell inductively coupled plasma mass spectrometry (CRC-ICP-MS/MS) were investigated in term of its accuracy and precision for producing reliable results. The radionuclides were extracted from 1 kg of the environmental soil samples by concentrated nitric and hydrochloric acids. The leachate solutions were measured directly by triple quadrupole CRC-ICP-MS/MS. For quality assurance, a chemical separation of the concerned radionuclides was conducted and then measured by single quadrupole-ICP-MS. The developed methods were next applied to measure the anthropogenic radionuclides 90Sr, 137Cs, 238Pu, 239Pu, and 240Pu in soil samples collected throughout the State of Qatar. The average concentrations of 90Sr, 137Cs, 238Pu, 239Pu, and 240Pu were 0.606 fg/g (3.364 Bq/kg), 0.619 fg/g (2.038 Bq/kg), 0.034 fg/g (0.0195 Bq/kg), 65.59 fg/g (0.150 Bq/kg), and 12.06 fg/g (0.103 Bq/kg), respectively.

UO2 as New Filling Material for Cesium Retention in High-Level Nuclear Waste Repositories

Abstract Depleted uranium dioxide has been proposed as an inert material to fill spent nuclear fuel canisters in geological repositories. Sorption capacity of this material to retain radionuclides released from the fuel was determined. Radiocesium is one of the radionuclides of concern in case of a nuclear accident or in a high-level nuclear waste repository and is highly mobile in aquatic systems. Results obtained in this work show that sorption of cesium on UO2 is a fast process (the equilibrium is reached in less than 1 h at pH 9).

Comparison of U.S. Environmental Protection Agency’s CAP88 PC Versions 3.0 and 4.0

The Savannah River National Laboratory (SRNL) with the assistance of Georgia Regents University, completed a comparison of the U.S. Environmental Protection Agency's (U.S. EPA) environmental dosimetry code CAP88 PC V3.0 with the recently developed V4.0. CAP88 is a set of computer programs and databases used for estimation of dose and risk from radionuclide emissions to air. At the U.S. Department of Energy's Savannah River Site, CAP88 is used by SRNL for determining compliance with U.S. EPA's National Emission Standards for Hazardous Air Pollutants (40 CFR 61, Subpart H) regulations. Using standardized input parameters, individual runs were conducted for each radionuclide within its corresponding database. Some radioactive decay constants, human usage parameters, and dose coefficients changed between the two versions, directly causing a proportional change in the total effective dose. A detailed summary for select radionuclides of concern at the Savannah River Site (60Co, 137Cs, 3H, 129I, 239Pu, and 90Sr) is provided. In general, the total effective doses will decrease for alpha/beta emitters because of reduced inhalation and ingestion rates in V4.0. However, for gamma emitters, such as 60Co and 137Cs, the total effective doses will increase because of changes U.S. EPA made in the external ground shine calculations.