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12.2% 171000 190M TOP 1% 154 6300

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The mutual reactions of the radiolysis products of water proceed in the bulk of the solution as homogeneous ones (see Table 6), thus competing with their reactions with a solute. However, in the absence of dissolved oxygen, complete decomposition of organic compounds also occurs, while the yield of the process is much lower.

Table 2 shows the ranges of microbial contamination of surface and groundwater.
Table 2 shows the ranges of microbial contamination of surface and groundwater.

Ionizing radiation sources for radiation technologies of aqueous system treatment

In radiation sources, isotope Cs-137 is used in the form of cesium chloride salt encapsulated in a metal shell. In radiation sources, radioisotope Co-60 is used in the form of metal slag or pellets.

Table 9. Parameters of generated electromagnetic radiation depending on electron beam energy (the data from [55]).
Table 9. Parameters of generated electromagnetic radiation depending on electron beam energy (the data from [55]).

Under-beam and other support equipment

1 - the Cockcroft-Walton and its improvements by Nissin-High Voltage, 2 - the insulated core transformer, 3 - the Dynamitron, 4 - a magnetically coupled DC system, and 5 - high current pulsating beams. In addition to an accelerator and a reactor, other equipment is required to operate the water/waste water radiation treatment facility.

Figure 2. Natural flow reactor with vertical (a) and horizontal (b) direction of electron-beam irradiation.
Figure 2. Natural flow reactor with vertical (a) and horizontal (b) direction of electron-beam irradiation.

Conclusion

Critical assessment of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals (∙OH/O ∙) in aqueous solution. Effect of oxidant addition on the elimination of 2-naphthalene sulfonate in aqueous solutions by electron beam irradiation. Gamma irradiation-induced complete degradation and mineralization of phenol in aqueous solution: effects of reagent.

Formation and decay of biphenyl during sequential radiolytic dechlorination of pentachlorobiphenyl in aqueous solution. Lead removal from aqueous solutions by electron beam treatment in the presence of a scavenger of OH radicals.

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Ionizing Radiation-Induced Polymerization

Introduction

Ionizing radiation is a promising technology for the preparation of cost-effective, efficient, safe and high-quality polymers. Energetic radicals resulting from ionizing radiation strike molecules causing electrons to be ejected from a certain orbit, then the atom becomes ionized [6]. To approach polymerization induced by ionizing radiation in high yield, the solvent selected must be ready for radiation radiolysis and of a high solubility order for the desired monomers.

Water radiolysis is the ionization of water molecules by absorbing the energy of ionizing radiation. The physical phase of primary interaction of ionizing radiation with water molecules results in excitation and ionization as expressed by Eqs.

Photo-initiated induced by UV irradiation

The role of the polymerization reaction initiation induced by UV irradiation "photoinitiator" is delayed with the conversion of the photon energy into a chemical energy in the form of a "reactive. The cross-linked density is high in the deeper level rather than the surface level depending on the oxygen concentration. While in free oxygen system, the cross-linked density is expected to be higher in the surface level rather than in the deeper level due to additional yield of radicals on the side exposed to UV radiation.

This process undergoes faster polymerization, for example, during the curing process of epoxy resins, the ring opens and initiates both radical and cationic polymerization mechanism. Further research is needed to cover undiscovered areas in the field of photoinduced polymerization [34].

Figure 2 shows water ionization by the UV rays that are capable to generate an active center (energetic radicals)
Figure 2 shows water ionization by the UV rays that are capable to generate an active center (energetic radicals)

Electron beam

It is evident that the cationic polymerization of epoxies is very quantitative and very fast, with a low activation energy [29]. First, poly(ethylene oxide-co-ethoxyl vinyl glycidyl ether) was synthesized by copolymerizing the corresponding anionic ring-opening monomers using radiation to initiate the reaction. A ring-opening random anionic copolymerization of a mixture of gaseous EO (boiling point 11 C) and the respective co-monomer in a suitable solvent can be initiated by an alkali metal alkoxide [33].

Radicals promote cationic photopolymerization, as it has been demonstrated to be a very effective method for the preparation of well-defined high molecular weight epoxy resin [35]. It is well known that ionizing and exciting species are, in fact, non-homogeneous and occur in groups called "spurs." The electron is similar to a "rock" hitting the surface of a pool of water, by the time the resulting "splashes" caused by the "rock hit" will expand and eventually overlap with their neighbors to result in a homogeneous distribution (Figure 6).

X-ray

In particular, the chemical reactions (radiolysis) occur when the reactive species of ions and radicals are non-homogeneously distributed in "clusters" of excitations/ionization (i.e. spores), and homogeneously after the reactive species are diffused and thermalized [38]. However, this simple picture is not true in some cases; the irradiation of non-aqueous systems does not give as clear a picture of outgrowths as is the case in water.

Gamma radiation

Details are shown in Figure 9 for polyethylene oxide only, all hydrogen atoms are equivalent in the polymer molecule, so the only type of macroradicals C• can be. As illustrated in the figure, hydrogen bond formation between chains increases the possibility of the polymerization mechanism to undergo intra-molecular "recombination" cross-linking rather than inter-molecular "disproportionation." However, in the case of oxygen gas, "disproportionation" reactions will lead mainly to the formation of carbonyl groups. The rate of polymerization by the cationic mechanism depends on the stability of the carbon ions in the macromolecules.

Also, in the polymerization of styrene in methylene chloride, Tsuda [64] has suggested that hydrogen chloride produced by the irradiation of chlorinated hydrocarbons causes the initiation of cationic polymerization of styrene. The transfer of positive charge in the phenyl ring gives a chance of addition onto the phenyl ring causing the formation of 3D cross-linked polymer.

Figure 8. The close system of water radiolysis induced by gamma rays.
Figure 8. The close system of water radiolysis induced by gamma rays.

Advantages of ionizing radiation-induced polymerization

As shown in Figure 12, initiation begins with the formation of Cl due to radiolysis of the solvent which is released as HCl giving a carbon cation at the styrene junctions. The propagation step is formed by head-to-tail addition in the carbocation polymerization. The β-hydrogen atoms of the spreading carbon cation are quite acidic, due to the delocalization of the positive charge [66] belonging to the phenyl ring. The final structure as seen in an ideal form (head to tail), sometimes, the propagation chain can be randomly rearranged.

Concluding remarks

Image gently advocates on the safety of radiation uses

Chemical modification of nano polyacrylonitrile prepared by gamma radiation induced emulsion polymerization and their use for removal of some metal ions. OH-radical induced cross-linking and strand breakage of poly(vinyl alcohol) in aqueous solution in the absence and presence of oxygen. High-dose radiolysis of aqueous solutions of chloromethanes: importance in radioactive organic waste storage.

Selection of our books indexed in the Web of Science™ Core Collection Book Citation Index (BKCI).

Recent Developments in Count Rate Processing Associated with Radiation Monitoring Systems

Nuclear counting model

Nuclear decay can occur through different processes depending on the A/Z ratio of the isotope in question. A probability of 1 p.k can be associated, respectively, with each branch of the test at any moment, as illustrated in figure 2. In a radioactive source containing a population of unstable nuclei, the decay of an individual nucleus does not affect the decay of others .

The number of countsN measured before observation time t is obtained by Eq. 9) with the detection efficiencyεand the probabilityηof the detected particle to be released during decay. At each timeti, sampled as ast0= 0 & ∀i≥1,ti=ti 1+∆t, the raw estimate of the counting rate ρ(ti) =ρi is provided by measuring Ni, which is a time-dependent random variable taking its values ​​in a Poisson distribution such as: . 11) A challenge in radiation monitoring is to provide count rate estimate ρi at each time ti.

Figure 2. Illustration of the Bernoulli trail applied to an individual nucleus disintegration.
Figure 2. Illustration of the Bernoulli trail applied to an individual nucleus disintegration.

Count rate smoothing

The algorithm translation of mi's update is to build infinite impulse response (IIR) dedicated to nuclear counting [9]. In the remainder of the discussion, we will conventionally use the notation ρbki to denote both the underlying random variable and its actual values. As illustrated in Figure 4, DT can be calculated thanks to the weighting of the standard deviation by Q1 α as: .

As illustrated in Figure 4, DL can be calculated thanks to the weighting of the associated standard deviation by the quantile Q1 β of the error function erf as: . At higher count rates (Figure 6), non-linear filtering allows the detection of the rate change ∆bρki >DLki.

Figure 4. Illustration of distributions D H
Figure 4. Illustration of distributions D H

Compensation measurement

This algorithmic building block plays a key role in the core counting methods studied in the following sections, namely compensation measurements and sensor network processing. Values ​​of ρA,i∆tandρB,i∆t the duration are described by Poisson processes, as already stated in the third section of this chapter. It is therefore necessary to reduce this variance by using a suitable smoothing filter, such as the CSTa non-linear filter described in the previous section (eq. 42).

In [19, 20], an approach is proposed in which a database is built from measurements obtained in representative areas and in the absence of the signal particle of interest: ρC= 0. The approach described in this section has been successfully implemented in various applications such as α/β contamination meters or gadolinium-based neutron detectors [20, 21].

Figure 7 synthetizes the principle, inputs, and outputs of the compensation technique.
Figure 7 synthetizes the principle, inputs, and outputs of the compensation technique.

Moving source detection

Many works have been done to recover the baseline (ω!1) and all use a database recorded when a representative sample of an empty vehicle passed through RPM [22, 23]. An alternative method based on time series analysis was developed to recover the baseline without using any prior knowledge of the vehicle and experimental conditions in the hope of increasing flexibility [24]. The state of the Si signal is indicated by a number between 1 and 8, defined as shown in Figure 9.

The first row describes the passage of the vehicle with the source without the shadow effect; the second line corresponds to the passage of a dense vehicle without a source; and the third to the passage of a dense vehicle containing a radioactive source (shadow protection). The states of Si can be determined by knowing Di and Si 1 using a sequential logic algorithm detailed in the form of a state diagram in Figure 10.

Figure 9. Schematic view of possible states of the system.
Figure 9. Schematic view of possible states of the system.

In particular, it has been established that the spectral analysis of the signal, even for unresolved detectors, enables a gain in detection performance [25]. The use of the empirical varianceσ2(Rϕ) ensures a significant gain in detection capability under challenging signal-to-noise ratios [27, 28]. This has been proven in [27-29], the largely significant added value in terms of detection capability- permits through the implementation of the correlation based detection.

Photography of the RPM prototype (Katrina) developed by the CEA in the framework of the SECUR-ED project funded by the European Commission [30]. Benchmark of the non-parametric Bayesian deconvolution method implemented in the SINBAD code for X-ray/γ-ray spectra processing.

Figure 12. Schematic of a system based on correlation detection.
Figure 12. Schematic of a system based on correlation detection.

Hình ảnh

Table 2. Examples of high detectable concentrations (per liter) of enteric pathogens and fecal indicators in different types of source waters.
Table 4. Wastewater characteristics in some industries (compiled from data of [17]).
Table 5. G-values of water radiolysis products at the end of “spur ” processes.
Table 8. Reactivity of radicals from water to some specific functional groups in organic compounds (high ++, medium +, low – , and very low – – ).
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