Liquid Radioactive Waste Storage Research Articles

Total Radiological Dose and Safety Assessment of Workers in Radioactive Liquid Waste Storage Location in Al Tuwaitha Site

This study aims to determine the total effective dose (external and internal) in the radioactive liquid Waste Hall (WH) in the Radiochemistry Laboratories building (RCL) in Al- Tuwaitha site in order to estimate the radiation risk for workers in this place. The external effective dose was calculated by an indirect method using ThermoLuminescent Dosimeters (LiF: Mg, Ti (TLD-100)) by placing them in the waste hall for one month. The internal effective dose was estimated by collecting eight air samples (environmental samples) from different locations in WH using an air sampler pump (Sniffer) to collect air samples loaded with particles or dust which are deposited on cellulose filter papers (φ 125mm). This was done for two flow rates the lowest and the highest values of the air sampler pump of 5CFM and 20CFM, respectively.The filter papers were chemically treated using the digestion method. The radionuclides in these samples were measured using a gamma spectrometry system equipped with a high-purity germanium detector (HPGe), and the radioactivity concentration was measured using a gross alpha beta gamma system. The results showed 137Cs of low concentration was deposited on the filter paper. The total annual effective dose rate (external and internal) results showed that the highest in WH was (6358.97μSv/year) for the low probability scenario and (1589.74 μSv/year) for the realistic scenario.

Nitrate-induced cancrinite precipitation in alkaline solution at low temperature and relevance to the Bayer alumina process

Cancrinite-type zeolites were proposed as functional materials which exhibits promising photocatalytic properties, enables carbon capture and can even be used in the storage of liquid radioactive waste. Conventional cancrinite is precipitated by reacting Na2CO3 or CaCO3 with Al- and Si- rich alkaline solutions at an elevated temperature of 150 °C in Bayer Alumina process. Here we report the effect of nitrate on cancrinite formation at 90 °C. At low alkalinity, nitrate accelerates transformation of zeolite LTA to sodalite, followed by minor cancrinite precipitation at a later stage. In highly alkaline solution, nitrate addition shortens the induction time required for homogenous cancrinite precipitation. In highly alkaline solutions with nitrate, it was also found that zeolite LTN precipitates as an intermediate phase which transforms into sodalite/cancrinite. Raman spectroscopy and thermogravimetric analysis confirmed the incorporation of nitrate into the structure of cancrinite and its thermal stability, at room temperature. These findings may help to optimize the Bayer process, mitigate the potential environmental risks of bauxite residue, and aid in the capture of the greenhouse gases from the air.

Retrieval and processing of radioactive muck settled in the bottom of radioactive liquid waste storage tanks

Alkaline radioactive liquid waste storage tanks contain huge quantity of chemical muck settled at the bottom of the tank. This muck contains fission products, corrosion products, actinides and other chemicals. As the precipitate remain settled for decades, the elements get converted from hydroxides to oxy-hydroxides and oxides which are difficult to dissolve in mineral acids. Treatment feasibility of this legacy muck was studied by simulating muck using acidic radioactive liquid waste followed by its dissolution and conditioning in borosilicate glass matrix. Dissolution was better in a mixture of nitric acid and oxalic acid medium. Immobilization studies of the muck dissolved solution in borosilicate glass showed that 25% waste oxide could be immobilized in glass matrix whereas when mixed with High Level liquid Waste (HLW), 34% waste oxide could be immobilized in glass matrix. Chemical durability and thermal stability of the glass samples were evaluated and are within the appropriate limit.

Риск заболеваемости солидными злокачественными новообразованиями у облученного на территории Восточно‑Уральского радиоактивного следа населения за 1957–2014 гг.

Purpose: Assessment of solid cancer incidence risk in the cohort of exposed population on the territory of the East Urals radioactive trace over the period of follow-up from 1957 to 2014 with the use of the individual doses provided by the latest TRDS dosimetry system.
 Material and methods: The explosion of the liquid radioactive waste storage tank at the «Mayak» Production Association on 29 September 1957 led to the pollution of the territories of the Chelyabinsk and Sverdlovsk Regions and the formation of the EURT, and the population residing on its territory was subjected to protracted chronic external and internal exposure. The analyzed cohort includes 21,384 people, 2,055 of whom received additional radiation before the 1957 accident due to residing in one of the Techa River settlements. The mean dose to the stomach for the members of the EURT cohort was 36 mGy, the maximum — 1.13 Gy. The analysis was performed using the DATAB and AMFIT programs (statistical software package EPICURE). A simple parametric model of excess relative risk (ERR) was used. Statistical significance and confidence intervals were obtained using the maximum likelihood method.
 Results: As a result of the analysis of the solid cancer incidence risk in the EURT cohort during the 57-year follow-up period using the linear model and the 5-year latent period, a statistically significant ERR was obtained which equals to 0.052 / 100 mGy (95 % CI 0.01–0.10, p = 0.02) in the entire EURT cohort. When the group of people additionally exposed on the Techa River before the 1957 accident was excluded from the cohort, the risk became insignificant. No significant modification of the dose dependence by non-radiation factors was revealed. The obtained results are compared well with the previous studies of the exposed population in the Southern Urals which were conducted in the Urals Research Center for Radiation Medicine, as well as in the world, devoted to the study of the effects of radiation exposure on population.

Растворение алюмосиликатных осадков в хранилищах жидких РАО

The article deals with the extraction of insoluble sediments formed in storage tanks during long-term storage of liquid radioactive waste from spent nuclear fuel reprocessing. Results of a thermodynamic analysis are presented enabling to assess the structure of the precipitation formed and to select most effective modes for thermal and hydrodynamic effects (cavitation technology) produced by liquid medium on eroded sediments. The paper presents the results of studies on the extraction of poorly soluble pulp components from storage tanks using cavitation technology.

Arguments for tightness testing of nuclear system pipeline parts, attached to pressureless tanks

Actual standard, namely Rules for design and safe operation of equipment and pipelines of nuclear power installations (2015) does not regulate strength and tightness testing of pipeline parts, located between valves and pressureless tanks of nuclear systems at nuclear power plants. This paper introduces arguments for strength and tightness test conduction of such areas of nuclear power plant pipelines, designed in accordance with Russian standards. It was also proposed some amendments for the norm aimed to improve safety and reliability of nuclear power plant systems with radioactive contamination. It was suggested to apply the result of current study to Leningradskaya-2 in order to improve safety and decrease the number of failures of the liquid radioactive waste storage system.

Risk analysis of high level radioactive waste storage tank based on HAZOP

High-level radioactive liquid waste tanks have the possibility of releasing radioactivity, and thus it is of great importance to identify hazards in such storage tanks and take measures to improve their safety. In this paper, a hazard and operability (HAZOP) methodology is used to identify the hazards in a double-shell stainless-steel tank for high-level radioactive liquid waste storage for which a risk matrix was implemented to assess the risks posed by the hazard. First, during the HAZOP process, appropriate process parameters and guidewords were selected to describe the deviation of the storage tank, and the causes and possible consequences of deviations as well as existing protection measures were analyzed. The risk matrix then was used to evaluate the risk level of the deviation identified, combined with the consequences of the deviation as well as the associated likelihood of its occurrence. Results showed that primary tank leaks and hydrogen combustion or explosion in tanks are undesirable risks, and thus corresponding countermeasures were put forward. The analysis results could be used to provide guidance for safe operation of, and rectification of hidden dangers in, high-level radioactive liquid waste storage tanks.

Радиологические аспекты обращения с жидкими радиоактивными отходами атомных станций

Purpose: The prospects and scale of the further development of nuclear energy depend to a large extent on the solution of the radioactive waste management (RW) problem. Special attention is given to management of the liquid radioactive waste (LRW), which poses the main potential hazard to the public and the environment, since LRW storage can lead to leaks into the environment.
 The purpose of the paper is to examine the radiological aspects of LRW management from nuclear power plants (NPPs) operation and to study the influence of the list of radionuclides controlled in RW on the evaluation of the efficiency of LRW treatment technology and on the validity of radioactive waste characterization and classification.
 Material and methods: The work is based on analysis of public materials (scientific publications, legal documents, international standards, recommendations of international organizations) in the area of LRW treatment and conditioning technologies, and methods of radioactive waste characterization, including information about accepted lists of controlled radionuclides.
 Results: It is shown that an unreasonable reduction of the list of controlled radionuclides can lead to a significant underestimation of the radiological hazard of RW packages transferred for disposal. In order to optimize the volume of RW radiation control, the radionuclide vector technology was proposed. It is stated that the technology is not universal and its application in each specific case requires additional justification. It is shown that the correctness of accounting for the radiological characteristics of radioactive waste can significantly influence the evaluation of the efficiency of the radioactive waste treatment technology. A possible approach to determining the acceptability of LRW treatment technology based on the characteristics of the final products formed is suggested.
 Conclusions: There is no universal approach to solve the problems of LRW treatment at the moment. A survey of the characteristics of LRW (chemical, physical, radiation) accumulated and formed during the operation of NPP with various types of reactors (VVER, RBMK, BN) should be performed to determine the initial requirements for LRW treatment technologies. A comprehensive analysis of the efficiency of LRW treatment technologies at all Russian NPPs is of interest with taking into account radionuclides that determine the radiological hazard of radioactive waste after the final disposal.

Development of a technology for protecting groundwater from 137Cs on the territory of the BN-350 reactor facility

The ability of clinoptilolite from the Chankanai deposit to take up 137Cs from groundwater and liquid radioactive waste from the BN-350 reactor facility on the territory of TOO MAEK-Kazatomprom in Kazakhstan was studied. The results of semicommercial tests demonstrate the efficiency of using clinoptilolite as a reagent material of the geochemical barrier for preventing the radionuclide migration into groundwater in case of leakage of tanks for storage of liquid radioactive waste. A design of the geochemical barrier was suggested.

The effectiveness of wastewater treatment in nuclear medicine: Performance data and radioecological considerations

For planned and ongoing storage of liquid radioactive waste in a designated plant for a nuclear medicine therapy ward (decontamination system/decay system), detailed knowledge of basic parameters such as the amount of radioactivity and the necessary decay time in the plant is required. The design of the plant at the Department of Nuclear Medicine of the University of Cologne, built in 2001, was based on assumptions about the individual discharge of activity from patients, which we can now retrospectively validate. The decontamination factor of the plant is at present in the order of 10−9 for 131I. The annual discharges have been continuously reduced over the period of operation and are now in the region of a few kilobecquerels. This work emphasizes the high efficacy of the decontamination plant to reduce the amount of radioactivity released from the nuclear medicine ward into the environment to almost negligible levels.

Research of Possibility of Sludge Complex Recycling in Low Radioactive LRW Storage Pools

In this article process of complex plasma utilization of sludge in low radioactive liquid radioactive waste (LRW) storage pools is investigated. It was also shown the possibility of effective air plasma utilization of such wastes in the form of optimal water-organic compositions with the adiabatic temperature of combustion higher than 1200 °C.

Calculation and Optimization of Plasma Processes of Utilization and Immobilization of Silts in Low Radioactive LRW Storage Pools

This work demonstrates the results of the research of plasma utilization and immobilization process using model silts of liquid radioactive waste (LRW) storage pools. The silts have the form of optimal water organic inflammable compositions. Also, the possibility of the application of magnetic separation for the effective extraction of solid utilization products from water suspension is shown.

Comparison of Experiments to Computational Fluid Dynamics Models for Mixing Using Dual Opposing Jets in Tanks With and Without Internal Obstructions

This paper documents testing methods, statistical data analysis, and a comparison of experimental results to computational fluid dynamics (CFD) models for blending of fluids, which were blended using a single pump designed with dual opposing nozzles in an 8-foot-diameter tank. Overall, this research presents new findings in the field of mixing research. Specifically, blending processes were clearly shown to have random, chaotic effects, where possible causal factors, such as turbulence, pump fluctuations, and eddies, required future evaluation. CFD models were shown to provide reasonable estimates for the average blending times, but large variations—or scatter—occurred for blending times during similar tests. Using this experimental blending time data, the chaotic nature of blending was demonstrated and the variability of blending times with respect to average blending times was shown to increase with system complexity. Prior to this research, the variation in blending times caused discrepancies between CFD models and experiments. This research addressed this discrepancy and determined statistical correction factors that can be applied to CFD models and thereby quantified techniques to permit the application of CFD models to complex systems, such as blending. These blending time correction factors for CFD models are comparable to safety factors used in structural design and compensate variability that cannot be theoretically calculated. To determine these correction factors, research was performed to investigate blending using a pump with dual opposing jets, which recirculate fluids in the tank to promote blending when fluids are added to the tank. In all, 85 tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of vertical cooling coils below the liquid surface for a full-scale, liquid radioactive waste storage tank. Also, different jet diameters and different horizontal orientations of the jets were investigated with respect to blending. Two types of blending tests were performed. The first set of 81 tests blended small quantities of tracer fluids into solution. Data from these tests were statistically evaluated to determine blending times for the addition of tracer solution to tanks, and blending times were successfully compared to computational fluid dynamics (CFD) models. The second set of four tests blended bulk quantities of solutions of different density and viscosity. For example, in one test, a quarter tank of water was added to three quarters of a tank of a more viscous salt solution. In this case, the blending process was noted to significantly change due to stratification of fluids and blending times increased substantially. However, CFD models for stratification and the variability of blending times for different density fluids were not pursued, and further research is recommended in the area of blending bulk quantities of fluids. All in all, testing showed that CFD models can be effectively applied if statistically validated through experimental testing, but, in the absence of experimental validation, CFD models can be extremely misleading as a basis for design and operation decisions.

Modern state of underground storage of liquid radioactive waste

Underground storage of liquid radioactive waste (LRW) has been successfully carried out in Russia over the past 40 years. Stages of development of the technology, its realization and chemical transformations of LRW components are considered and discussed, as well as the modern approach to underground storage. Control of the state of waste products and migration radionuclides and toxic compounds remains the key issue of providing safety of LRW storage. Radiation thermal and biochemical transformations of components of waste form new chemical compounds and, first of all, gases. The formation of gases is one of the important factors determining the safety of underground LRW storage.

Normal axial skeleton structure in common roach Rutilus rutilus (Actinopterygii: Cyprinidae) and malformations due to radiation contamination in the area of the Mayak (Chelyabinsk Province, Russia) nuclear plant

This study was designed to describe normal axial skeletal structure in common roach Rutilus rutilus from putative unaffected environmental conditions, and the occurrence of skeletal malformations in the fish from an area under radiation contamination. Specimens were collected from water bodies of the Techa Cascade Reservoirs located near the Mayak atomic industry plant in the River Ob' drainage, Chelyabinsk Province, Russia. One sample was collected from Lake Irtyash, a reservoir of drinkable water, supplying the town of Ozersk, and the other one from a technical reservoir which is a storage of liquid radioactive waste from Mayak and characterized by high radioactive contamination (mostly (90)Sr and (137)Cs). A comparison was made with historical material collected from the River Ob' before the middle of the 20th century, i.e. before the environment became affected by radioactive contamination. A high number of abnormalities of the axial skeleton were detected in both Mayak samples, in 94 and 97% of examined specimens, in contrast to about 20% in the historical specimens. The abnormalities were in both the unpaired fins and the vertebral column, including the caudal complex and included supernumerary elements, fusions, deformities and displacement of the elements. Most axial skeleton abnormalities, however, were minor, such as splitting, shortening or deformation of spines. Severe defects, such as extensive scolioses, lordoses and kyphoses, were not found. The causes of the abnormalities were not identified in this study, but the high incidence of malformations may be attributed to genetically determined imbalance during development. The almost equal distribution of abnormalities among the fish from non-contaminated and radioactive contaminated reservoirs may be explained by either recent gene flow within the population of R. rutilus in the River Techa system or the effect of unknown unfavourable environmental factors such as chemical pollution.

Legal Aspects of the Safety of the Techa Cascade of Reservoirs—Liquid Radioactive Waste Storage Facilities

In Russia in 1950–1960 solutions for the localization and storage of large volumes of liquid radioactive waste produced during defensive tasks were accomplished using natural and man-made water objects. At present, they are non-isolated from the environment and radioactive waste storage facilities constitute a serious potential menace. These objects are not allowed by the current legislation of the Russian Federation on environmental protection and safety. However, they do exist and there are no definite and approved engineering solutions regarding their removal. One of these objects is the Techa Cascade of Reservoirs (TCR) of the Mayak plant. In this article, TCR protection requirements are based on and formalized taking into account the legislation of the Russian Federation and the biospheric approach to the radiation protection of humans and the environment. Special safety requirements are needed because the standard argument “from human exposure to discharge standards” is invalid owing to the fact that the possibility of using water objects that have had contact with the TCR is restricted by law.

Analysis of reconstruction of the composition of liquid radioactive waste released into the Techa River in 1949 1956

An analysis of archival data of liquid radioactive waste samples and Techa River bottom sediments was made, taking into consideration the radiochemical methods for extraction and beta-emitting radionuclide activity measurements existing in the early 1950s. It was stated that the radionuclide composition of the routine and accidental liquid radioactive waste releases in 19491951 corresponded to the radionuclide composition of the fission products accumulated in the nuclear reactor fuel and in the liquid radioactive waste storage tank, with operating modes typical for that time period in reactor and radiochemical plants. It was stated that the data obtained by Ilyin (1956) for the assessment of radionuclide composition and liquid radioactive-waste release rate in the Techa River were not correct, and for retrospective assessment of the population exposure dose for near-stream residents, this could result in substantial underassessment of the data obtained.

Physicochemical Processes Occurring in Long-Term Storage of Liquid Radioactive Waste in Deep Underground Collector Beds

Interaction under hydrothermal conditions (pressure 3 MPa; temperature 80-170°C; contact time up to 2500 h) of intermediate-level acidic waste with bed rock of the underground repository for liquid radioactive waste is studied. Transformation of rock-forming minerals under these conditions is accompanied by increasing absorption of 137Cs, 90Sr, 239Pu, 241Am, and 238U.

Movements and Radionuclide Concentrations of Sage Grouse in Southeastern Idaho

Movements and radionuclide concentrations of sage grouse (Centrocercus urophasianus) summering near nuclear facilities on the Idaho National Engineering Laboratory in southeastern Idaho were studied from 1977 through 1980. From 10 July through 7 September, 95% of all locations (N = 131) of radiomarked grouse were within 2 km of their feeding areas on lawns surrounding the facilities. During October and November, 82% of all radiolocations (N = 22) were greater than 2 km from these areas. The maximum 1-way movement to winter range was 81 km. Radionuclide concentrations (primarily radiocesium) were higher (P = 0.05) in sage grouse summering near a facility with liquid radioactive waste storage than in grouse summering near a solid radioactive waste disposal area or in control areas. The short biological halflife of the ingested radionuclides and the timing of sage grouse movements from summering areas reduced any potential radiation dose to a person consuming 1 of these birds. J. WILDL. MANAGE. 47(1):169-177 Radionuclides are similar to other environmental pollutants because they can enter biological cycles and may pose a danger to components of these cycles, including wildlife and man (Woodwell 1967). The transport of radionuclides from disposal sites by wildlife has been investigated (Brisbin et al. 1974, Straney et al. 1975, Cadwell et al. 1979, Springer 1979, Halford et al. 1981); however, much of this research has dealt with waterfowl or mammals. Sage grouse are attracted to nuclear facilities on the Idaho National Engineering Laboratory (INEL) in southeastern Idaho (Connelly 1982) by an abundance of forbs and free water during the summer. Some birds move off-site just prior to or during the hunting season. The objectives of our study were to: (1) document the number of sage grouse and their residence time at INEL facilities, (2) define sage grouse movement patterns away from INEL facilities, (3) document the kinds and amounts of radionuclides accumulated by grouse summering near INEL facilities, and (4) calculate the potential dose commitment to a person consuming a sage grouse shortly after it left the vicinity of an INEL nuclear facility. This study was supported by the Office of Health and Environmental Research, U.S. Department of Energy. Technical assistance was supplied by the Idaho Department of Fish and Game. We thank all of the individuals from the above agencies who contributed to this study. We are especially grateful to W. J. Arthur and I. J. Ball for administrative guidance, advice, and field assistance. I. J. Ball, R. J. Jonas, J. M. Peek, and V. Schultz reviewed earlier drafts of this paper. C. Braun and 2 anonymous referees also provided helpful comments on this manuscript.