Liquid scintillation waste

Commonly, in vitro determination of HDAC activity is a manual assay utilizing a coupled two-step process, including enzymatic deacetylation of a substrate followed by reaction termination and readout [10]. Assays utilize nuclear extracts and substrates containing labeled (radioactive or fluorescent) acetylated histones. For the isotope-based assays, the enzymes are incubated with acetate-radiolabled histones prepared from chicken reticulocytes or chemically [ Hjacetylated peptide substrates, and the enzymatic activity is determined by liquid scintillation counting [11]. Alternatively, histones may be obtained from cells following treatment with [ H]acetyl-CoA [12]. The caveats of these approaches include the variability of prelabeled acetylated core histones within preparations, potential high costs, their labor-intensive nature and the presence of radioactive waste. 

The examples for radioactive labeling by phosphorus-32 ( P) and iodine-125 ( 1) in this chapter were chosen for two reasons on one hand, they are relatively easy to do, and on the other hand, the measurement of radioactivity is simple. is counted in water in a liquid scintillation counter by measuring the Cerenkov radiation and is measured in a gamma counter. Both isotopes may be detected also by autoradiography. A further advantage of both isotopes is their short half-life, which eases the disposal of nuclear waste. 

Low-Level Waste Low-level waste (LLW) consists of contaminated dry trash, paper, plastics, protective clothing, organic liquids such as liquid scintillation samples, and the like. LLW is produced by any facility that handles radioactive materials such as nuclear power plants, medical facilities, colleges, and so forth. In the United States, commercial LLW is sent to one of three disposal sites (Barnwell, South Carolina, Richland, Washington, and Clive, Utah). Due to the limited size of these sites (and similar disposal sites through the world) and steeply escalating costs for waste disposal, the primary goal of LLW treatment prior to disposal is volume reduction, either by incineration or compaction, followed... 

Aliquat 336 TEVA-Resin "Tc determination in SI system using stopped-flow detection for nuclear waste On-line liquid scintillation 44... 

Exempt Radioactive Wastes. The radioactive waste classification system in the United States does not include a general class of exempt waste (see Table 1.1). Rather, many products and materials that contain small amounts of radionuclides (e.g., specified consumer products, liquid scintillation counters containing 3H and 14C) have been exempted from requirements for use or disposal as radioactive material on a case-by-case basis. The various exemption levels are intended to correspond to low doses to the public, especially compared with dose limits in radiation protection standards for the public or doses due to natural background radiation. However, the exemption levels are not based on a particular dose, and potential doses to the public resulting from use or disposal of the exempt products and materials vary widely. 

Saarinen, L. and J. Suksi. 1992. Determination of uranium series radionuclides Pa-231 and Ra-226 using liquid scintillation counting (LSC). In Report on the Nuclear Waste Commission of Finnish Power Companies. Technical Report YJT-92-20, Helsinki, Finland. 

Cell harvesters were developed to capture multiple samples of cells on membrane filters, wash away unincorporated isotopes, and prepare samples for liquid scintillation counting on special equipment developed to process and count multiple samples. Despite miniaturization and improvements in efficiency of this technique, the disadvantages of multiple liquid handling steps and increasing costs for disposal of radioactive waste materials severely limit its usefulness. Although specific applications require measuring DNA synthesis as a marker for cell proliferation, much better choices are available for detecting viable cell number for HTS. 

Calcium-41 Ca-41 is produced by neutron activation of natural Ca-40. It has been found to exceed the GQ by a factor of 2 in both graphite fuel struts and desiccant from HNA (3 streams). The reported desiccant value is an upper limit probably based on trace contamination by graphite dust. In decommissioning wastes, activation of the concrete bioshield would also be expected to produce Ca-41 but these wastes streams are regarded as low level wastes in the NIREX inventory and hence GQ values do not apply. Measurements of Ca-41 can be obtained after chemical separation of Ca, which is done routinely for Ca-45 measurements. After any Ca-45 (t 14 =163 days) has decayed away, it can be measured by liquid scintillation counting. Procurement of direct standards from NPL would be required. In fresh samples, if the Ca-45 has been measured, then the Ca-41 could be estimated by comparison of activation... 

Other methods currently in use for Ca determination in concretes are based entirely on precipitations for purification of the Ca. Suarez et al (2000) utilise a chromate precipitation for removal of Ba and Ra from the solution. This is a pH dependant precipitation, and the chromate solution resulting from this requires a separate waste stream. The method has a total of 9 steps after sample dissolution, and has decontamination factors of >10" for Ba and Co, >10 for Sr and >10 for Eu. The minimum detectable activity by liquid scintillation counting is 0.29 Bq/g for Ca (0.034 Bq/g Ca). 

EASY METHOD OF CONCENTRATION OF STRONTIUM ISOTOPES FROM RADIOACTIVE AQUEOUS WASTES FOR THE DETERMINATION OF SR BY LIQUID SCINTILLATION COUNTING. APPLICATION OF STRONTIUM EMPORE RAD DISKS... 

This study emphasizes the measurement procedure of Sr activity in radioactive aqueous waste produced by the nuclear industry. Considering radioecological and radioprotective elements, there is a need for systematic measurements of Sr activity in rejected wastes. The classical methods for this determination are gas flow proportional counting, liquid scintillation counting or Cherenkov counting.These techniques require efficient concentration and purification steps before the measurement of radiostrontium itself. 

The accreditation in accordance with Belgian standard NBN EN ISO/IEC 17025 is now obtained for the determination of the activity of Sr in radioactive wastes by liquid scintillation. It s based on the conclusive results of the different tests carried out to validate the procedure. 

Homogeneous. The eluate is mixed with liquid scintillant before passing through the flow cell. The sample is passed to waste after counting. 

The tritium measurement protocol Is relatively simplistic and consists of neutralization of the sample, single plate distillation, removal of an appropriate size aliquot (usually eight mL.) via reproducible automatic pipets and the addition of 15 mL. of dark adapted scintillation cocktail under Incandescent lighting conditions. After shaking to ensure a uniform gel, the sample is allowed to settle and dark adapt for up to twenty but no more than sixty minutes. The liquid scintillation unit efficiency Is determined dally on a previously prepared standard and background measurements are determined at least dally. Quench corrections are not applied to the system due to the lack of an external standards ratio capability and an effort to minimize the amount of hazardous waste which would be generated if an Internal standards approach were adopted. 

Minimize the waste s hazards. Waste minimization methods specific to chemical, radioactive, or biological waste can be applied to multihazardous waste to mitigate or eliminate one hazard, which wOl then allow it to be managed as a single-hazard waste. For example, the substitution of nonignitable liquid scintillation fluid (LSF) for toluene-based LSF reduces a chemical-radioactive waste to a radioactive waste. 

Increasing costs of radioactive waste and solvents have made it necessary to apply new approaches in LSC sample preparation. New liquid scintillators are capable of incubating twice as much or even more of aqueous samples than the classical colloidal scintillator systems with a stable and smaller and uniform size micelle formation and without formation of viscous liquid crystals. Counting efficiency remains at the same level as before when using small vials fitting inside of the standard classical ones. 

A liquid scintillation instrument does not only produce counts, but also radioactive waste. If we consider that an average instrument counts 20.000 samples per year using 200 liters of liquid scintillator, it produces more than this as waste. If the instrument uses 10 ml scintillator with 1 ml active sample and processes 20.000 experiments per year, it creates 220 liters of liquid and about 1.500 liters of solid waste from disposable plastic vials. Now the radioactive waste is usually destroyed by combustion, while earlier a considerable part of such aqueous - organic waste was poured into the regular sewage system. 

Today the handling of waste is covered in varying extent by governmental regulations in all countries, and is causing considerable waste treatment bills. The costs of disposal of the solid and liquid radioactive waste vary, but in many countries the disposal costs are close to the costs of scintillators. Also controversially today the disposable type of vial represents the majority of costs in the waste treatment. 

The disposal of radioactive waste continues to be a problem. The additional complications created by the chemical toxicity of toluene, dioxane and other LSC solvents impose a problem of waste disposal which may soon place severe restrictions on research involving radioactive tracers, especially where radioactivity is measured by means of liquid scintillation counting. There is need for intelligent, decisive action on the part of regulatory agencies reflecting perspective, relevance and objectivity with regard to waste disposal. Such action must be taken soon. 

The most extensive use of RIA has been in the clinical laboratory for the diagnosis of metabolic malfunction and disease and for the management of therapy. For clinical applications an RIA must meet certain requirements. Accuracy, for example, should normally be +/- 10% or better. Owing to the great number of assays that must be performed, simplicity of methodology and economy are important considerations. It is desirable to use the same tube for both the reaction and for counting to reduce cost and to reduce the number of necessary operations. The use of small tubes and vials helps achieve an economic utilization of reagents and, in the case of liquid scintillator, also helps to reduce the problem of radioactive and chemically hazardous waste. 

The utility of bead injection SIA for separation and preconcentration has been well demonstrated by the selective determination of strontium-90, americium-241, and technetium-99 along with various isotopes of plutonium and curium whose radionuclide activity was determined in nuclear waste samples using liquid scintillation counting. 

Separate solid and liquid wastes. Radioactive wastes must be separated into solids (absolutely no liquids are permitted) and liquids. Liquid wastes must be kept separate according to chemical reactivity. For example, do not mix wastes containing acids with liquids containing bases, and do not mix aqueous liquids with organic liquids. Keep flammable organic solvent radioactive wastes in safety cans. Animal carcasses and liquid scintillation vials are also kept separate. 

Claycamp, H.G., H. Cember, E.A. Port. 1977. Volume reduction of liquid scintillation counting wastes. Health Phys. 34 716-718. 

The first method for sampling liquid waste involved a serial dilution with liquid scintillant before liquid scintillation (LS) coimting to determine total B activity. The second method for sampling solid waste involved pyrolysis of a sample contained within a polypropylene bottle, approximately 2 g total wei t 0.5 g sample weight (Figure 1). A sample of this size was considered the maximmn allowable in order to ensure a controlled and safe combustion using the Carbolite Combustion Tube Furnace MTT 12/38/850 (Figure 2). 

In medical installations, the use of radioactive isotopes for diagnosis and therapy has significantly increased in the past years. Nonencapsulated radioactive elements are used for different purposes such as in diagnosis by tracers, treatment of thyroid or blood disorder, and in medical research. These activities produce some solid radioactive wastes like cotton, rubber gloves, syringes, etc., as well as liquid wastes, mainly scintillation liquids. Another type of waste is the encapsulated sources that are used for cancer treatment these elements must be changed when their activity decays below a certain level. 

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