Kapok fiber composites minimizing secondary waste and disposal costs for large-scale radioactive liquid treatment.

Conventional liquid treatments for large-scale, low-level radioactive wastewater, such as ion exchange and waste solidification, face challenges due to the large amounts of secondary waste and high disposal costs. A new large-scale decontamination method is proposed that uses kapok fiber composites for rapid radionuclide adsorption and high volume reduction to minimize secondary waste. The composite consists of natural zeolite and kapok holocellulose, which has high water-soaking ability and low-temperature pyrolysis. The kapok composites, fabricated using a commercial wet-laid nonwoven manufacturing process, absorbs 99% of low-level radioactive cesium in 20 min, reducing the volume by 98% and the weight by 47% at 300 °C. The low-temperature pyrolysis process below 300 °C prevents cesium desorption and gasification by avoiding zeolite destruction. The mass-producible kapok composites can be used for adsorbing various radionuclides in large-scale wastewater by attaching specific adsorbents for target isotopes to the composites.

Removal of cobalt and strontium by adsorption using Brewer's spent grain formed by pyrolysis.

One byproduct of brewing beer is Brewer's spent grain (BSG), which is reused in animal feed. However, BSG has valuable potential for other products such as biochar because of its high protein and fiber content. Radioactive waste is one of the biggest concerns in Korea because of the permanent shutdown of the Gori nuclear power plant. In this study, we aimed to use BSG-850, a biochar originating from BSG after pyrolysis at 850 °C, for the adsorption of cobalt (Co) and strontium (Sr), which are two radionuclides that contribute to radioactive waste. The adsorption capacity of Co and Sr was reinforced with increased temperature which are 3.304, 4.659, 5.516 mg/g (Co) and 1.462, 2.54, 3.036 mg/g (Sr) at 298, 308, and 318 K, respectively. The reusability of BSG-850 capacity was 75.3, 47.8, 43.6, 36.2% and 93.6, 84.2, 57.2, and 32.7% after 1, 2, 3, and 4 cycles, for Co and Sr, respectively. In the presence of other competitive ions, the adsorption capacity decreased. The adsorption capacity and properties of BSG-origin biochar for Co and Sr were confirmed and BSG can be a desirable option for solving radioactive waste issue.

SAFETY IMPROVEMENT OF THE RADIOACTIVE WASTE STORAGE FACILITY IN ALBANIA.

The Albanian National Radioactive Waste Storage Facility (NRWSF) constructed in 1999 consists of an interim waste storage facility for very low level waste, low level waste, intermediate level waste and disused sealed radioactive sources (DSRS) coming from research institutions, agriculture and industrial activities and from applications in nuclear medicine in Albania. The safety assessment of this facility is performed considering its impact to workers, public and environment. In 2018, Albania started a new National project Alb 9010 titled 'Upgrading the Radioactive Waste Storage Building According to International Standards'. The two fundamental objectives are to ensure the protection of the public, workers and the environment and to ensure retrievability of waste packages for final disposal. The project focuses on ensuring the safety of the treatment, conditioning and storage of radioactive waste and DSRS. Under this project has been done the improvement of the safety of the RWSF and upgrading of the existing building infrastructure. In the end of the project the objective is to improve the safety of the personnel in the RWSF, protection of public and environment, Upgrade the Equipment's used in the RW Management Activities, Upgrade the existing Infrastructure of the RWSF Building and also ensure retrievability of waste packages for final disposal.

Design of an IoT-based indoor tracking and condition monitoring system for the safe and transparent management of drums storing low- and intermediate-level radioactive waste.

Regulatory agencies and civil society organizations concerned with radioactive waste management are demanding maximized safety management of radioactive-waste-containing drums using advanced technology for more efficient and safe management. In the present paper, we propose a sensor system that can track and monitor drums containing low- and intermediate-level radioactive waste using advanced technology based on the Internet of Things (IoT). The proposed system consists of drum nodes, pallet nodes, and gateways. A drum node and magnetic sensor installed on a drum can be used to remotely check whether the drum lid is open or closed, and the location of the drum can be tracked using a near-field communication reader and an infrared module installed on the pallet node. Considering that radioactive waste is stored for a long time period, the proposed sensors are designed for low power consumption. Moreover, a pilot test involving 48 drums and 12 pallets was conducted to verify the system prototype. Accordingly, from the results of the pilot test, drawbacks were noted and solutions were proposed to improve the system in future work. Implications: We designed a test bed by fabricating a sensor-system prototype and used it in a simulation experiment. The results of this study will be used as basic data for establishing safety measures for radioactive waste management in the future through computer simulation of radioactive waste anomalies in a digital-twin system.

Advances in the management of radioactive wastes and radionuclide contamination in environmental compartments: a review.

Several anthropogenic activities produce radioactive materials into the environment. According to reports, exposure to high concentrations of radioactive elements such as potassium (40K), uranium (238U and 235U), and thorium (232Th) poses serious health concerns. The scarcity of reviews addressing the occurrence/sources, distribution, and remedial solutions of radioactive contamination in the ecosystems has fueled data collection for this bibliometric survey. In rivers and potable water, reports show that several parts of Europe and Asia have recorded radionuclide concentrations much higher than the permissible level of 1 Bq/L. According to various investigations, activity concentrations of gamma-emitting radioactive elements discovered in soils are higher than the global average crustal values, especially around mining activities. Adsorption technique is the most prevalent remedial method for decontaminating radiochemically polluted sites. However, there is a need to investigate integrated approaches/combination techniques. Although complete radionuclide decontamination utilizing the various technologies is feasible, future research should focus on cost-effectiveness, waste minimization, sustainability, and rapid radionuclide decontamination. Radioactive materials can be harnessed as fuel for nuclear power generation to meet worldwide energy demand. However, proper infrastructure must be put in place to prevent catastrophic disasters.

Self-cleaning and regenerable nano zero-valent iron modified PCN-224 heterojunction for photo-enhanced radioactive waste reduction.

The expansion of large-scale nuclear power causes a substantial volume of radioactive wastewater containing uranium to be released into the environment. Because of uranium's toxicity and bioaccumulation, it is critical to develop the efficient and sustainable materials for selective removal of uranium (VI). Herein, a regenerable anti-biofouling nano zero-valent iron doped porphyrinic zirconium metal-organic framework (NZVI@PCN-224) heterojunction system was successfully fabricated. Due to the Schottky-junction effect at the NZVI/MOF interface, the NZVI nanomaterial immobilized on PCN-224 could improve interfacial electron transfer and separation efficiency, and enhance entire reduction of highly soluble U(VI) to less soluble U(IV), involving photocatalytic reduction and chemical reduction. Meanwhile, the photocatalytic effect also prompts the NZVI@PCN-224 to produce more biotoxic reactive oxygen species (ROS), resulting in high anti-microbial and anti-algae activities. Under dark conditions, NZVI@PCN-224 with a large specific surface area could provide sufficient oxo atoms as the uranium binding sites and show the highest uranium-adsorbing capability of 57.94 mg/g at pH 4.0. After eight adsorption-desorption cycles, NZVI@PCN-224 still retained a high uranium adsorption capacity of 47.98 mg/g and elimination efficiency (91.72%). This sorption/reduction/anti-biofouling synergistic strategy of combining chelation, chemical reduction and photocatalytic performance inspires new insights for highly efficient treatment of liquid radioactive waste.

Using molybdenum carbiding to induce digestion of carbon in H2O2: A sustainable approach to eliminate radioactivity for hazardous graphite waste inherited from nuclear enterprise.

To properly manage nuclear wastes is critical to sustainable utilization of nuclear power and environment health. Here, we show an innovative carbiding strategy for sustainable management of radioactive graphite through digestion of carbon in H2O2. The combined action of intermolecular oxidation of graphite by MoO3 and molybdenum carbiding demonstrates success in gasifying graphite and sequestrating uranium for a simulated uranium-contaminated graphite waste. The carbiding process plays a triple role: (1) converting graphite into atomic carbon digestible in H2O2, (2) generating oxalic ligands in the presence of H2O2 to favor U-precipitation, and (3) delivering oxalic ligands to coordinate to MoVI-oxo anionic species to improve sample batching capacity. We demonstrate > 99% of uranium to be sequestrated for the simulated waste with graphite matrix completely gasifying while no detectable U-migration occurred during operation. This method has further been extended to removal of surface carbon layers for graphite monolith and thus can be used to decontaminate monolithic graphite waste with emission of a minimal amount of secondary waste. We believe this work not only provides a sustainable approach to tackle the managing issue of heavily metal contaminated graphite waste, but also indicates a promising methodology toward surface decontamination for irradiated graphite in general.

Capture of I131 from medical-based wastewater using the highly effective and recyclable adsorbent of g-C3N4 assembled with Mg-Co-Al-layered double hydroxide.

This paper reports a very high capacity and recyclable Mg-Co-Al-layered double hydroxide@ g-C3N4 nanocomposite as the new adsorbent for remediation of radioisotope-containing medical-based solutions. In this work, a convenient solvothermal method was employed to synthesize a new nano-adsorbent, whose features were determined by energy dispersive X-ray (EDS/EDX), XRD, FESEM, TEM, TGA, BET, and FT-IR spectroscopy. The as-prepared nano-adsorbent was applied to capture the radioisotope iodine-131 mainly from the medical-based wastewater under different conditions of main influential parameters, (i.e. adsorbent dose, initial I2 concentration, sonication time, and temperature). The process was evaluated by three models of RSM, CCD-ANFIS, and CCD-GRNN. Furthermore, comprehensive kinetic, isotherm, thermodynamic, reusability cycles and optimization (by GA and DF) studies were conducted to evaluate the behavior and adsorption mechanism of I2 on the surface of Mg-Co-Al-LDH@ g-C3N4 nanocomposite. High removal efficiency (95.25%) of 131I in only 30 min (i.e. during 1/384 its half-life), along with an excellent capacity that has ever been reported (2200.70 mg/g) and recyclability (seven times without breakthrough in the efficiency), turns the nanocomposite to a very promising option in remediation of 131I-containing solutions. Besides, from the models studied, ANFIS described the process with the highest accuracy and reliability with R2 > 0.999.

Synthesis of ZnO nanoparticle-anchored biochar composites for the selective removal of perrhenate, a surrogate for pertechnetate, from radioactive effluents.

Pertechnetate (TcO4-) is a component of low-activity waste (LAW) fractions of legacy nuclear waste, and the adsorption removal of TcO4- from LAW effluents would greatly benefit the site remediation process. However, available adsorbent materials lack the desired combination of low cost, radiolytic stability, and high selectivity. In this study, a ZnO nanoparticle-anchored biochar composite (ZBC) was fabricated and applied to potentially separate TcO4- from radioactive effluents. The as-synthesized material exhibited γ radiation resistance and superhydrophobicity, with a strong sorption capacity of 25,916 mg/kg for perrhenate (ReO4-), which was used in this study as a surrogate for radioactive pertechnetate (TcO4-). Additionally, the selectivity for ReO4- exceeded that for the competing ions I-, NO2-, NO3-, SO42-, PO43-, Cu2+, Fe3+, Al3+, and UO22+. These unique features show that ZBC is capable of selectively removing ReO4- from Hanford LAW melter off-gas scrubber simulant effluent. This selectivity stems from the synergistic effects of both the superhydrophobic surface of the sorbent and the inherent nature of sorbates. Furthermore, density functional theory (DFT) calculations indicated that ReO4- can form stable complexes on both the (100) and (002) planes of ZnO, of which, the (002) complexes have greater stability. Electron transfer from ReO4- on (002) was greater than that on (100). These phenomena may be because (002) has a lower surface energy than (100). Partial density of state (PDOS) analysis further confirms that ReO4- is chemisorbed on ZBC, which agrees with the findings of the Elovich kinetic model. This work provides a feasible pathway for scale-up to produce high-efficiency and cost-effective biosorbents for the removal of radionuclides.

Construction of hydrophobic interface on natural biomaterials for higher efficient and reversible radioactive iodine adsorption in water.

For the pollution of radioactive materials, it is of great importance to develop efficient adsorbents for radioactive iodine adsorption in aqueous solution. In this work, a simple and green strategy was developed to construct hydrophobic surface on natural cotton fibers (n-CF) based on organic-soluble carbon dots (OCDs) for the first time. The results demonstrated the successful constructed hydrophobic n-CF@OCDs expressed excellent stability and selectivity for iodine (I2) adsorption in water. The maximum adsorption capacity for I2 on n-CF@OCDs is calculated to be 190.1 mg g-1, which is about 6.8 times higher than that of n-CF (28.1 mg g-1), this highly I2 adsorption efficiency should be attributed to the hydrophobic properties of adsorbent. The adsorption mechanism was also discussed in this work. In addition, the adsorbed I2 could be desorbed easily with a simple reductive process at ambient conditions, which can lead to not only the restore of I2 but also the recycling of adsorbent, illustrating their good practicability. Furthermore, this universal strategy can also be used for construction of hydrophobic surface on various natural biomaterials, demonstrating its potential application in constructing of hydrophobic surface and used for the adsorption and removal of nonpolar pollutions or radioactive waste in aqueous solutions.

NCRP Program Area Committee 5: Environmental Radiation and Radioactive Waste Issues.

Program Area Committee 5 of the National Council on Radiation Protection and Measurements (NCRP) focuses its activities on environmental radiation and radioactive waste issues. Historically this Committee addressed emerging issues of the nation pertaining to radioactivity or radiation in the environment or radioactive waste issues due either to natural origins or to man-made activities. The Committee continues to identify such issues in the future.

Microbial fouling and corrosion of carbon steel in deep anoxic alkaline groundwater.

Understanding the corrosion of carbon steel materials of low and intermediate level radioactive waste under repository conditions is crucial to ensure the safe storage of radioactive contaminated materials. The waste will be in contact with the concrete of repository silos and storage containers, and eventually with groundwater. In this study, the corrosion of carbon steel under repository conditions as well as the microbial community forming biofilm on the carbon steel samples, consisting of bacteria, archaea, and fungi, was studied over a period of three years in a groundwater environment with and without inserted concrete. The number of biofilm forming bacteria and archaea was 1,000-fold lower, with corrosion rates 620-times lower in the presence of concrete compared to the natural groundwater environment. However, localized corrosion was detected in the concrete-groundwater environment indicating the presence of local microenvironments where the conditions for pitting corrosion were favorable.

An assessment of strontium sorption onto bentonite buffer material in waste repository.

In the present study, changes occurring in sorption characteristics of a representative bentonite (WIn-BT) exposed to SrCl2 (0.001-0.1 M) under the pH range of 1-13 were investigated. Such interaction revealed a significant variation in surface charge density and binding energy of ions with respect to bentonite, and alteration in their physicochemical properties viz., specific surface area, cation exchange capacity, thermal and mechanical behaviour were observed. The distribution coefficients (k d) calculated for sorption onto virgin (UCBT) and contaminated bentonite (CBT) indicated a greater influence of mineralogical changes occurred with variance of pH and strontium concentration. Notably, the sorption mechanism clearly elucidates the effect of structural negative charge and existence of anionic metal species onto CBT, and depicted the reason behind significant k d values at highly acidic and alkaline pH. The maximum k d of UCBT and CBT(0.001M SrCl2) were 8.99 and 2.92 L/kg, respectively, at the soil pH 8.5; whereas it was 2.37 and 1.23 L/kg at pH 1 for the CBT(0.1M SrCl2) and CBT(0.01M SrCl2), respectively. The findings of this study can be useful to identify the physicochemical parameters of candidate buffer material and sorption reversibility in waste repository.

Emerging Environmental Justice Issues in Nuclear Power and Radioactive Contamination.

Nuclear hazards, linked to both U.S. weapons programs and civilian nuclear power, pose substantial environment justice issues. Nuclear power plant (NPP) reactors produce low-level ionizing radiation, high level nuclear waste, and are subject to catastrophic contamination events. Justice concerns include plant locations and the large potentially exposed populations, as well as issues in siting, nuclear safety, and barriers to public participation. Other justice issues relate to extensive contamination in the U.S. nuclear weapons complex, and the mining and processing industries that have supported it. To approach the topic, first we discuss distributional justice issues of NPP sites in the U.S. and related procedural injustices in siting, operation, and emergency preparedness. Then we discuss justice concerns involving the U.S. nuclear weapons complex and the ways that uranium mining, processing, and weapons development have affected those living downwind, including a substantial American Indian population. Next we examine the problem of high-level nuclear waste and the risk implications of the lack of secure long-term storage. The handling and deposition of toxic nuclear wastes pose new transgenerational justice issues of unprecedented duration, in comparison to any other industry. Finally, we discuss the persistent risks of nuclear technologies and renewable energy alternatives.

Hydrophilic Clicked 2,6-Bis-triazolyl-pyridines Endowed with High Actinide Selectivity and Radiochemical Stability: Toward a Closed Nuclear Fuel Cycle.

There is still an evident need for selective and stable ligands able to separate actinide(III) from lanthanide(III) metal ions in view of the treatment of the accumulated radioactive waste and of the recycling of minor actinides. We have herein demonstrated that hydrophilic 2,6-bis-triazolyl-pyridines are able to strip all actinides in all the different oxidation states from a diglycolamide-containing kerosene solution into an acidic aqueous phase. The ascertained high actinide selectivity, efficiency, extraction kinetics, and chemical/radiolytic stability spotlight this hydrophilic class of ligands as exceptional candidates for advanced separation processes fundamental for closing the nuclear fuel cycle and solving the environmental issues related to the management of existing nuclear waste.

Investigation of an Accidental Radiological Release in an Underground Disposal Facility.

A radioactive release took place at the Waste Isolation Pilot Plant near Carlsbad, New Mexico, on 14 February 2014. An alarm from a Continuous Air Monitor caused a switch from unfiltered to filtered air exiting the facility through High-Efficiency Particulate Arrestance filters. The activity measured on the filters demonstrated first order decay, indicating that the release was a single release. The facility was reentered in April 2014 and photographic evidence pointed to a single breached 55-gallon drum that originated at Los Alamos as the source of the release. Data were collected and analyzed to verify the source and cause of the release.

Using Geographic Information Systems to Determine Site Suitability for a Low-Level Radioactive Waste Storage Facility.

Radioactive waste is an inevitable product of using radioactive material in education and research activities, medical applications, energy generation, and weapons production. Low-level radioactive waste (LLW) makes up a majority of the radioactive waste produced in the United States. In 2010, over two million cubic feet of LLW were shipped to disposal sites. Despite efforts from several states and compacts as well as from private industry, the options for proper disposal of LLW remain limited. New methods for quickly identifying potential storage locations could alleviate current challenges and eventually provide additional sites and allow for adequate regional disposal of LLW. Furthermore, these methods need to be designed so that they are easily communicated to the public. A Geographic Information Systems (GIS) based method was developed to determine suitability of potential LLW disposal (or storage) sites. Criteria and other parameters of suitability were based on the Code of Federal Regulation (CFR) requirements as well as supporting literature and reports. The resultant method was used to assess areas suitable for further evaluation as prospective disposal sites in Louisiana. Criteria were derived from the 10 minimum requirements in 10 CFR Part 61.50, the Nuclear Regulatory Commission's Regulatory Guide 0902, and studies at existing disposal sites. A suitability formula was developed permitting the use of weighting factors and normalization of all criteria. Data were compiled into GIS data sets and analyzed on a cell grid of approximately 14,000 cells (covering 181,300 square kilometers) using the suitability formula. Requirements were analyzed for each cell using multiple criteria/sub-criteria as well as surrogates for unavailable datasets. Additional criteria were also added when appropriate. The method designed in this project proved to be sufficient for initial screening tests in determining the most suitable areas for prospective disposal (or storage) sites. Cells above 90%, 95%, and 99% suitability include respectively 404, 88, and 4 cells suitable for further analysis. With these areas identified, the next step in siting a LLW storage facility would be on-site analysis using additional requirements as specified by relevant regulatory guidelines. The GIS based method provides an easy, economic, efficient and effective means in evaluating potential sites for LLW storage facilities where sufficient GIS data exist.

[RADIATION SAFETY DURING REMEDIATION OF THE "SEVRAO" FACILITIES].

Within a framework of national program on elimination of nuclear legacy, State Corporation "Rosatom" is working on rehabilitation at the temporary waste storage facility at Andreeva Bay (Northwest Center for radioactive waste "SEVRAO"--the branch of "RosRAO"), located in the North-West of Russia. In the article there is presented an analysis of the current state of supervision for radiation safety of personnel and population in the context of readiness of the regulator to the implementation of an effective oversight of radiation safety in the process of radiation-hazardous work. Presented in the article results of radiation-hygienic monitoring are an informative indicator of the effectiveness of realized rehabilitation measures and characterize the radiation environment in the surveillance zone as a normal, without the tendency to its deterioration.

[RADIATION HYGIENIC MONITORING AT THE AREA OF THE LOCATION OF THE FAR EASTERN CENTER FOR RADIOACTIVE WASTE MANAGEMENT (FEC "DALRAO"--BRANCH OF FSUE "ROSRAO")].

Intensification ofactivities in the field of spent nuclear fuel (SNF) and radioactive waste (RW) management in the Far East region of Russia assumes an increase of the environmental load on the territories adjacent to the enterprise and settlements. To ensure radiation safety during works on SNF and radioactive waste management in the standard mode of operation and during the rehabilitation works in the contaminated territories, there is need for the optimization of the existing system of radiation-hygienic monitoring, aimed at the implementation of complex dynamic observation of parameters of radiation-hygienic situation and radiation amount of the population living in the vicinity of the Far Eastern Center for Radioactive Waste Management (FEC "DALRAO"). To solve this problem there is required a significant amount of total and enough structured information on the character of the formation of the radiation situation, the potential ways of the spread of man-made pollution to the surrounding area, determining the radiation load on the population living in the vicinity of the object. In this paper there are presented the results of field studies of the radiation situation at the plant FEC "DALRAO", which were obtained during the course of expedition trips in 2009-2012.