Low-level Radioactive Waste Management Research Articles

An approach towards enhancing the role of microwave heating in low-level radioactive waste management

Nuclear industries, medical industries, and nuclear research establishments generate a considerable amount of low-level radioactive waste (LLW). The paper presents the application of microwave energy for the processing of low-level radioactive wastes (volume reduction). A temperature-based study of these kinds of wastes has been performed using the COMSOL multiphysics software package. The simulated results agree well with experiments performed on a commercially available microwave oven at a frequency of 2.450 GHz. The main focus of this paper involves a detailed study of the effectiveness of microwave heating for treatment of LLW based on their dielectric loss tangent data. The study is carried out by recording the temperature rise in the corresponding waste materials, which is basically representation of the conversion of the applied electromagnetic energy into heat. Various shapes such as cubical, cylindrical, and cuboid of low-level radioactive test objects have been incorporated in the treating environment (Oven). Further, measurement of electromagnetic and heat transfer properties of the test objects has been performed to improve the accuracy of the simulation and experimental results. Many combinations of test objects with different shapes and dielectric properties have been studied for microwave heat treatment. The study suggests that radioactive waste treatment using microwave heating will be more effective after categorizing the wastes concerning their dielectric loss tangent.

Low-level radioactive waste management using microwave technology

Low-level radioactive waste is the inevitable outcome of many industrial, medical applications and nuclear power plants. This type of low-level waste is, however, also very hazardous, and its proper disposal is necessary as it may leak and contaminate soil and water, leading to both the environment and human health issues. The disposition and storage of the radioactive waste in its original form is very much critical and expensive, hence the pre-processing, including the proper procedure for the storage allocation is necessary for effective handling of this waste disposal. Most common approaches of preprocessing are “replace,” “reduce,” “reuse,” and “recycle.” The “reduce” approach is explored in this study using the novel microwave technology to handle the low-level radioactive waste. This approach has never been used before for this purpose. The applicability of the proposed method is validated using medical waste such as tissue papers, plastic carry bags, etc., and industrial waste such as Teflon tubing, concrete, glass, wood, etc., as test objects. These test objects (waste materials) are first categorized here based on their dielectric loss in order to explore the possibility of heating them using either the microwave or the conventional heating process. The heating process can effectively reduce total waste volume in a short span of time. The categorization of these materials is carried out by placing them into the prototype concealed environment to avoid any radioactive leakage. Finally, microwave technology is actually applied for the first time to monitor the online reduction in the volume of waste during the treatment processes.

Review of Waste Acceptance Criteria in USA for Establishing Very Low Level Radioactive Waste Acceptance Criteria in the 3rd Step Landfill Disposal Site

According to the Korea Radioactive Waste Agency’s (KORAD’s) medium and low level radioactive waste management implementation plan, the Domestic 3rd Step Landfill Disposal Facility has planned to accept a total of 104,000 drums (2 trenches) of very low level radioactive waste (VLLW), from the decommissioning site from April 2019 - February 2026 (total budget: 224.6 billion Won). Subsequently, 260,000 drums (5 trenches) will be disposed in a 34,076 m2. Accordingly, KORAD is preparing a waste acceptance criteria (WAC) for this facility. Every disposal facility for VLLW in other countries such as France and Spain, operate their WAC for each VLLW facility with a reasonable application approach, This, paper focuses on analyzing the WAC conditions in VLLW sites in the USA and discusses whether these can be met in domestic VLLW WAC. It also helps in the preparation of WAC for the 3rd Step Landfill Disposal Site in Gyeongju, since the USA has prior experience on decommissioning nuclear waste.

Position Statement of the Health Physics Society PS009-3: Low-level Radioactive Waste Management

*Health Physics Society, 1313 Dolley Madison Blvd., Suite 402, McLean, VA 22101. The authors declare no conflicts of interest. (Manuscript accepted 18 January 2018)

Vermiculite as a potential component of the engineered barriers in low- and medium-level radioactive waste repositories

Abstract Vermiculite (VMT) was tested as a low-cost, eco-friendly adsorbent for the removal of cesium(I), strontium(II), europium(III), americium(III), and technetium(VII) radionuclides from aqueous solutions. The raw material was characterized and checked as potential adsorbent. The removal efficiency (Er, %) was studied as a function of the main factors important for the management of radioactive liquid wastes. It was found that the uptake from the aqueous solutions simulating the radioactive liquid wastes was in the order: Cs(I) Sr(II) (both about 95%) > Am(III) (about 90%) > Eu(III) (about 80%). When a reducing agent is added to the solution technetium-99 may also be completely removed. The usefulness of VMT in liquid low level radioactive waste management has also been confirmed by checking its radiation stability. Vermiculite can be considered as a promising material for sorption of the radionuclides from radioactive waste solutions and as a potential additive to the engineered barriers in LLRW repositories.

Neutron Deep Penetration Calculations in Light Water with Monte Carlo TRIPOLI-4® Variance Reduction Techniques

Nuclear decommissioning takes place in several stages due to the radioactivity in the reactor structure materials. A good estimation of the neutron activation products distributed in the reactor structure materials impacts obviously on the decommissioning planning and the low-level radioactive waste management. Continuous energy Monte-Carlo radiation transport code TRIPOLI-4 has been applied on radiation protection and shielding analyses. To enhance the TRIPOLI-4 application in nuclear decommissioning activities, both experimental and computational benchmarks are being performed. To calculate the neutron activation of the shielding and structure materials of nuclear facilities, the knowledge of 3D neutron flux map and energy spectra must be first investigated. To perform this type of neutron deep penetration calculations with the Monte Carlo transport code, variance reduction techniques are necessary in order to reduce the uncertainty of the neutron activation estimation. In this study, variance reduction options of the TRIPOLI-4 code were used on the NAIADE 1 light water shielding benchmark. This benchmark document is available from the OECD/NEA SINBAD shielding benchmark database. From this benchmark database, a simplified NAIADE 1 water shielding model was first proposed in this work in order to make the code validation easier. Determination of the fission neutron transport was performed in light water for penetration up to 50 cm for fast neutrons and up to about 180 cm for thermal neutrons. Measurement and calculation results were benchmarked. Variance reduction options and their performance were discussed and compared.

Comparison of low-pressure reverse osmosis filtration and polyelectrolyte-enhanced ultrafiltration for the removal of Co and Sr from nuclear plant wastewater

Abstract Volume reduction and the concentration of long-lived radioactive species are critical issues for the management of liquid low-level radioactive waste. This study investigated and compared the performances of low-pressure reverse osmosis (LPRO) and polyelectrolyte-enhanced ultrafiltration (PEUF) for the removal of target metals (Co and Sr) from simulated low-level radioactive waste. The effects of dosage and types of chelating polymers, such as polyacrylic acid (PAA) and polyethylenimine (PEI), were evaluated at acidic and neutral pH levels. The metal removal efficiencies by precipitation at acidic pH (4.5) and neutral pH (6.5) were marginal. The addition of PAA to LPRO had no effect on metal removal, but had a negative impact on membrane permeability, particularly at acidic pH levels. The LPRO itself already achieved sufficient metal rejection; therefore, the addition of PAA only caused fouling. In contrast, the PAA dosage and solution pH governed the metal rejection in PEUF. Deprotonated PAA molecules bound to metal ions, but the distribution of PAA species had no significant impact on flux decline. The PEUF with PEI exhibited almost no pH dependency in metal removal, but showed metal-specific removal behaviors. The PEUF with PAA achieved metal removal as high as LPRO, with relatively high water permeability.

Synergistic combination of metal oxide adsorbents for enhanced fouling control and metal removal in a submerged membrane adsorber

Selective contaminant removal and concentration methods are essential for low level radioactive waste management. Herein, the synergy achieved by dosing a mixture of metal oxide adsorbents (crystalline silicotitanate (CST) and ferrihydrite (FH)) into a submerged membrane adsorber for the removal of key metal species (Co2+, Sr2+, and Cs+), and the degree of membrane fouling control in nuclear plant laundry wastewater treatment were investigated. Substantial and stable removal of metal ions (>90%) was achieved when the concentration of CST in the reactor was maintained at levels as high as 0.3g/L, whereas the effect of FH varied significantly depending on the target metals. High and constant metal removal by CST was attributed to the ion exchange based sorption reaction in the CST cavities. CST itself did not mitigate membrane fouling, whereas the use of FH prevented fouling even at high dosages. Interestingly, the combination of CST and FH effectively eliminated fouling, which could not be achieved with CST alone. Combination of even small amounts of FH (0.1g/L as Fe) with CST effectively reduced fouling. Thus, the synergistic effect of the CST and FH mixed adsorbent system on fouling control can be ascribed to the contribution of FH particles. FH exhibited high capacity for sorption of a key foulant in the feedwater constituents, i.e., the nonionic surfactant Tween 80. FH had a much greater sorption capacity for Tween 80 than CST. Possible binding of multivalent metal ions to the surfactant anchored on FH could furnish further repulsive forces between the FH particles, thereby making the cake layer looser. Dosing of the CST and FH adsorbent mixture into the membrane adsorber enabled enhanced metal removal with simultaneous fouling control.

Use of poly(methyl methacrylate) in radioactive waste management: II. Monte Carlo simulations

Radioactive waste is generated from the nuclear applications and it should properly be managed in a radioactive waste management system. Different methods are available for treatment and conditioning of radioactive waste. Polymers can be used in the radioactive waste management as an embedding matrix. Poly(methyl methacrylate (PMMA) is a possible candidate material that can be used in the low level radioactive waste management. In this study, based on total resistible dose for PMMA, maximum waste activity that can be embedded into a waste drum was found via Monte Carlo simulations. In addition, Monte Carlo simulations for radioactive waste embedded into above mentioned polymer was performed and the dose rate distribution in the polymer matrix was determined for the initial and different periods of 15.1, 30.2 and 302 years after embedding of waste. Changes of mechanical properties in the polymer embedded waste drum was simulated for PMMA embedded waste matrices based on experimental data.

Reconsidering the law and economics of low-level radioactive waste management

Several countries are striving to ensure adequate long-run disposal space for low-level radioactive waste (LLRW). In the United States, the Low-Level Radioactive Waste Policy Act of 1980 and its 1985 amendments comprise a menu of incentives and penalties designed to motivate the construction of regional LLRW disposal facilities—the operating premise. Congress wished to intervene in the marketplace to bring about a more equitable solution to the LLRW management problem. Some investigators forewarned years ago that the federal law was both inefficient and inequitable. Additionally, however, the law has proved ineffectual, as only one new disposal facility has emerged and that one (at Clive, UT) was created outside of the federal incentive structure. This article (1) provides an argument as to why the LLRW Act of 1980 and its subsequent amendments failed to elicit the regional system of LLRW facilities it envisioned, and (2) complements this argument with a comprehensive model of LLRW management.

Canada's Low-level Radioactive Waste Disposal Problem: Voluntarism Reconsidered

Voluntary siting methods are no more successful than conventional regulatory or market-based methods in siting new low-level radioactive waste (LLRW) disposal facilities. The promise of voluntarism, I argue, is diminished by the excessively local conception of public participation that typically informs voluntary siting attempts. This is evident in Canada's search for an LLRW disposal facility in Ontario. Placing strong boundaries around municipalities for purposes of public participation violates two key conditions of democratic siting policy - maximising social inclusiveness and ensuring a large unit of review. Selecting a larger unit of public deliberation would have permitted a more socially inclusive participatory analysis of the political, economic and social implications of managing radioactive wastes. A regional approach to LLRW management can therefore provide a more just and democratic framework for resolving siting disputes that jointly involve neighbouring communities.

Évaluation de l'impact radiologique de différentes voies de gestion des déchets TFA

Radiological impact assessment of very low-level radioactive waste management pathways. Two approaches are currently being adopted for the management of very low-level waste (VLLW): disposal in surface facilities and, for some categories of VLL waste, the implementation of treatment and utilisation channels. In this paper, the orders of magnitude of the radiological consequences which may result from these two options are discussed, in a matter of a description rather than a comparison. As regards disposal, radiological impact is presented through a generic case, along with the uncertainties stemming from the variability of the parameters associated with its design, as well as those associated with the geosphere and the biosphere. In the case of treatment and utilisation channels, such as disposal or recycling of VLL waste oils or VLL wastes containing asbestos, the assessment of radiological consequences deals with the public exposure and with the occupational exposure on the basis of a stage-by-stage breakdown of the industrial process.

Studies of sorbent/ion-exchange materials for the removal of radioactive strontium from liquid radioactive waste and high hardness groundwaters

Different sorbents were studied in terms of their full-scale applicability for radioactive strontium removal in low-level liquid radioactive waste (LLRW) management. The following types of sorbent/ion-exchange materials were investigated: natural zeolite–clinoptilolite, modified natural clinoptilolite, synthetic zeolites, new synthetic crystalline materials selective to strontium, ion-exchange resins, and modified fiber sorbents. Simulated solutions for experimental tests were prepared according to the composition of one of the facilities at the Hanford nuclear site (Richland, WA, USA). The following experiments were performed at different concentrations of strontium and competing elements (calcium, on the first hand): batch tests for determination of strontium distribution coefficients, sorbent/ion-exchanger selectivity to strontium in the presence of calcium, and kinetic measurements of strontium uptake. Modifications of Amberlite and Duolite ion-exchange resins (Rohm and Haas, USA) and new synthetic crystalline materials — silicotitanate IE-911 (UOP, USA) and sodium titanate (Allied Signal, USA) — showed the highest distribution coefficients of strontium ( K d∼ 2×10 4–4×10 5 ml/g). For all materials, the K d decreased significantly with increased calcium concentration. On the other hand, each of these sorbents showed poor selectivity to strontium in the presence of calcium. Newly developed sorbents (Institute of Chemistry, Vladivostok, Russia) based on a fiber matrix (FM and FP) showed the best relative selectivity to strontium followed by the natural zeolite (clinoptilolite extracted and produced in the USA). Synthetic zeolites (IE-96, TIE-96) had moderate values of both parameters (distribution coefficient and selectivity). Fiber sorption materials were also absolute leaders in kinetic measurements removing 40% to 60% of the strontium from solution within a few minutes.

A large-scale laboratory experiment to determine the mass transfer of CO 2 from a sandy soil to moving groundwater

Gaseous 14CO 2 originating from low-level radioactive wastes, buried in the unsaturated zone, can be released to the environment via two major routes: gas-phase diffusion through soils to the atmosphere, and by dissolution in groundwaters followed by aqueous migration. The fate of this gas is important for the safety of waste management areas and for waste disposal, because the exposure to humans depends upon the aqueous versus atmospheric path. One key parameter that influences the relative importance of these paths is the transfer to groundwaters, expressed as the mass transfer coefficient K L. Due to the nature of the capillary fringe, located just above the water table, the K L can not be calculated and it has to be obtained experimentally. In this study, a large sand bin (3.5×2×1 m) that featured a flowing aquifer was used to determine K L. The means of the experimental values of K L ranged from 1.9 to 3.1×10 −4 m/h, depending upon the pH interface condition. These K L-values are ∼15 to 25 times lower than the mass transfer to a quiescent liquid (4.7×10 −3 m/h). This suggests that the capillary fringe offers a significant resistance to mass transfer, and this should be accounted for in the calculations of the fate of 14CO 2 near waste management areas. This mass transfer coefficient was used to determine the fluxes and the fate of both CO 2 and 14CO 2 gases originating from a low-level radioactive waste management area. The fate of these gases was calculated using a simple box model applied to a hypothetical 1 m 2 plot extending from groundwater to the soil surface. Two values of K L were used to calculate the fluxes from groundwater: the experimental K L, and a `theoretical' K L calculated from the mass transfer to a quiescent liquid, corrected for porosity and tortuosity. Box model calculations predicted that most of the CO 2 emitted to the atmosphere originated from the soil column, regardless of the K L used (experimental or calculated). The same box model using site 14CO 2 data, however, predicted that radiocarbon emissions originated from the contaminated aquifer. In this case, the box model was sensitive to K L. If a calculated rather than experimental K L-value was used, the amount of 14CO 2 loss from groundwater was substantially overestimated.

Evaluation of uranium and arsenic retention by soil from a low level radioactive waste management site using sequential extraction

The European Communities Bureau of Reference (BCR) and Chunguo sequential extraction procedures were employed to evaluate the retention of U and As by a soil contaminated with low level radioactive waste. Modifications were made to both procedures to optimize the measurement of soil and extractant samples using epithermal neutron activation analysis. Based on the BCR procedure, approximately 20% of the U appeared to be bound to the carbonate fraction, 10% to the mineral oxide fraction and 20% to the organic fraction. In the case of As, the majority was strongly bound in the residue fraction. The results obtained with the Chunguo procedure supported these conclusions to some extent, in that the majority of the U and As was found to be strongly bound to the soil in a manner consistent with its presence in the residue fraction.

Environmental monitoring for a low-level radioactive waste management facility: incinerator operations.

An environmental monitoring program has been developed for Harvard University, Southborough campus, to assess the local environmental concentrations of radionuclides released in incinerator effluents. The campus is host to the University's low-level radioactive waste management facility, which consists of 6,000 drum capacity decay-storage buildings; a 250 drum capacity decay-storage freezer; and a controlled-air incinerator. Developmental considerations were based on the characteristics and use of the incinerator, which has a capacity of 8 tons per day and is operated 5% of the time for the volume reduction of Type 0 and Type 4 wastes contaminated with a variety of radionuclides used in biomedical research-some in microsphere form. Monitoring was established for air, leafy vegetation, leaf-litter, and surface soil media. Field sampling was optimized regarding location and time based on the action of atmospheric, terrestrial, and biotic transport mechanisms. Preliminary results indicate transient concentrations of 3H and 125I in vegetation directly exposed to the dispersing plume. Measurable particulate depositions have not been observed.

Radioactive waste management in developing and newly industrialized countries

Radioactive wastes are mostly produced in countries with military nuclear programmes. However, non-nuclear weapon countries, with solely commercial nuclear industries, also produce radioactive wastes. Moreover, uranium and thorium mining and milling wastes, as well as other kinds of low-level radioactive wastes like those resulting from radiological accidents, can also be found in developing and newly industrialized countries. The paper discusses the principal forms of low-level radioactive waste management in the latter countries. In addition, other aspects will be included into the discussion because social, economical and political implications cannot be ignored by responsible decision makers either in the nuclear industry or in the regulatory bodies.

95/00828 CRC handbook of management of radiation protection programs - Second Edition

Organization and Management of a Radiation Safety Office (Steven H. King and Rodger W. Granlund). Organization and Management of a Nonionizing Radiation Safety Program (Zorach R. Glaser). Organization and Management of a Laser Safety Program (Kelly L. Classic). Management of Low-Level Radioactive Waste (John R. Vincenti). Management of Monitoring Programs (R. Craig Yoder). Management of Radiation Therapy Patients (Donald E. Velkley). Management of Emergency Care for Radiation Accident Victims (Mary Ellen Berger and Robert C. Ricks). Evaluation and Control of Internal Radiation Exposures on the Basis of Committed Dose Equivalent (Kenneth W. Skrable). Properly Relating Radiation Protection Requirements to Relative Radiotoxicity and Risk (Allen Brodsky). Radiation Emergency Planning - Damage, Evaluation, and Control Procedures (Robert G. Gallaghar). Planning for and Management of Radiation Accidents (Sydney W. Porter, Jr.). Emergency Response Decisions in the Planning Process - Predetermined Conditions for Predetermined Actions (James A. Martin, Jr.). Accident Consequence Projection (Thomas J. McKenna and Joseph G. Giitter). Education and Training in Radiation Protection (Allen Brodsky, Phyllis L. Brodsky, and Kenneth L. Mossman). Education and Training for Radiation Protection in Nuclear Power Plants (Charles A. Willis). Requirements and Preparation for Passing the American Board of Health Physics Certification Examinations (Charles A. Willis). Education and Training of Radiologic Technologists (Dolores A. Thomas). Summary of Experience in Radiation Litigation (Vincent P. Collins). Legal Aspects of Health Physics Record Keeping (Donald E. Jose). Preparing for Court Appearances (Donald E. Jose). Radiological Controls Documentation in Radiation Injury Litigation (Gordon M. Lodde).

Electoral Support and the Capture of Legislators: Evidence from North Carolina's Vote on Radioactive Waste Disposal

Empirical tests of Stigler's (1971) theory of economic regulation using roll-call voting of legislators have ignored Stigler's hypothesis that secure legislators behave differently from insecure legislators. In this study of legislator voting on the Southeast Low-Level Radioactive Waste Management Compact in North Carolina, the extent to which legislators' votes represent the economic interests of their geographic constituencies is significantly influenced by the support they expect to receive in reelection campaigns. Moreover, there is weak evidence in favor of Stigler's supposition that more secure legislators are more likely to vote the general interest than are their less secure colleagues.

Design of a temporary radioactive waste storage facility

The impact of radioactive waste in King Abdulaziz University has given rise to the need for a temporary radioactive waste storage made of reinforced concrete (R.C.). In the framework of more recent ICRP recommendations and IAEA technical guidelines, the radiation protection requirements and the applicability of low level radioactive waste management have been suggested. The design and performance have been analyzed through civil engineering inspections and shielding calculations for any corrective actions. This paper specifies the radiation protection criteria for a storage facility and for the management of low level radioactive waste (LLRW).