Radiation Processing Applications Research Articles

Metal–organic frameworks as optically stimulated luminescence dosimeter

Metal–organic frameworks (MOF) have been vigorously investigated as hybrid materials in recent decades due to their exceptional structural versatility and applications in diverse fields. The development of novel MOFs for radiation detection and luminescence-based dosimetry is the latest topic of interest. In this contribution, we have synthesized and characterized a Uranyl MOF, which shows an optically stimulated luminescence (OSL) phenomenon induced by ionizing radiation. OSL dosimetric studies were carried out on Uranyl MOF, which revealed that MOF has a linear dose–response up to 100 Gy with a 1.1 Gy minimum detection dose. It also shows good reusability, around 30% fading in one day, very low fading beyond one day to 30 days, and decent radiation stability (stable up to 10 kGy). Preliminary dosimetry results are promising and show that Uranyl MOF can be utilized in the field of low-dose radiation processing applications in the future.

Electron paramagnetic resonance signal in wheat seeds irradiated with low-energy electron beam

Radiation processing applications for food and agricultural products require to control the applied doses values. This investigation shows the potential of using electron paramagnetic resonance (EPR) spectrometry for dosimetric control of wheat seeds irradiated at the URT-0.5 (0.5 MeV) linear electron accelerator. The general view of the wheat EPR spectra in the dose range 0–20 kGy is presented. The temporal kinetics of the entire spectrum and separated peaks has been studied. The EPR signal integral intensity dependences on the absorbed dose were obtained.

Transit dose measurements using alanine and diode-based dosimeters

The growing interest in low-dose (< 100 Gy) radiation processing applications has raised concerns about accurately measuring the absorbed dose in irradiated materials. Depending on the irradiator design, the transit time due to the radioactive source movement (or the product itself) until the stable irradiation position might affect the predicted absorbed dose. This work aims to evaluate the transit dose in a 60Co Gammacell 220-Nordion irradiator, which has radioactive sources settled at the bottom of a lead shielding. When the facility is on, the product and the dosimeter are mechanically guided down to the irradiation position, and hereafter the selected exposure time starts to be counted. At the end of irradiation, both product and dosimeter rise to the initial position enabling them to be gathered by the operator. The product is continuously irradiated at different dose rates during its fall and rise movement, preventing the transit dose from being obtained straightforward. The experimental approach adopted is to assess the transit time, and thus the transit dose, using an online diode-based dosimetry system previously calibrated against reference standard alanine dosimeters. The agreement between the transit doses attained with the diode (0.41 ± 0.02) Gy and alanine ((0.38 ± 0.01) Gy validates the method herein proposed.

Determination of Quality Parameters and Sensory Attributes of ‘Jaffa’ Oranges Irradiated as Postharvest Quarantine Treatment Throughout Long-Term Cold Storage

The Mediterranean fruit fly (Ceratitis capitata) is one of the major problems in the citrus producing and trading countries including Turkey. Commercial application of radiation processing can be the alternative and effective solution to overcome this problem. The objective of the present study was the determination the sensory attributes, quality parameters and also cold storage shelf-life of ‘Jaffa’ oranges (Citrus sinensis (L) Osbeck) irradiated (0, 0.5, 1.0 and 1.5 kGy) as considering postharvest quarantine treatment for the Mediterranean fruit fly (Ceratitis capitata). The quality parameters of the control and irradiated oranges were determined in terms of weight loss, pH, titratable acidity, total soluble solids, reducing sugars, vitamin C content, total carotenoids, pectin, color of fruit during cold storage at 4 ± 0.1 oC and 85 - 90 % relative humidity (RH) on the 0, 15, 30 and 45 d of storage. Obtained results showed that, low dose irradiation is applicable regarding as other significant quality parameters of ‘Jaffa’ oranges such as vitamin C, total carotenoids, invert sugars, pectin, weight loss, pH, acidity and total soluble solids did not affect consumption and commercial value of ‘Jaffa’ sweet oranges up to 45 d of storage at 4 oC. According to overall sensory attributes, irradiated fruit were still acceptable as judged by panelists and ≤1.0 kGy irradiation dose more suitable for keeping important attributes of processed ‘Jaffa’ orange fruit.

Characterization of a thin photodiode as a routine dosimeter for low-dose radiation processing applications

The characterization of a dosimetry system based on a commercial PIN photodiode as a routine dosimeter in a 60Co industrial facility is reported. The main parameters of the dose rate response (repeatability, reproducibility, and angular dependence) and the dose response (dependence on both dose rate and accumulated dose) are investigated. The results obtained, within a dose rate range of 3.7–52.8 Gy/h and doses up to 200 Gy, fully adhere to the standard protocols established for radiation processing dosimetry. The diode performance as a routine dosimeter is validated by the good overall agreement with radiochromic films and alanine dosimetry.

High radiation dose studies of kappa-carrageenan in dilute aqueous solution

Crosslinking or degradation of polysaccharides is one of the most important applications of radiation processing. Kappa-carrageenan (κ-carrageenan), one of the most frequently studied polysaccharides, is known to undergo degradation when exposed to ionizing radiation. In this work, irradiation of 1% κ-carrageenan solution (Mw 1.14 × 106 Da) at high radiation doses of 100–300 kGy resulted in an increase in molecular weight. The average molecular weight (Mw) increased from 5600 to 60,000 Da and 7500 to 69,000 Da with gamma and electron-beam irradiation, respectively. UV analyses of irradiated 1% solution showed an increasing absorbance at 265 nm, while FT-IR spectra still displayed some important functional groups and showed an increasing carbonyl and double bond groups with doses up to 300 kGy. The antioxidant properties also increased with dose but leveled off at 100 kGy. Further irradiation to 500 kGy led to the formation of microgels with a size of <5 μm under SEM, indicating the presence of a crosslinked chain of κ-carrageenan. The lowering of solution pH due to the release of sulfate groups during irradiation and the radical formation on the alkyl group of the side chain may be responsible for the radiation crosslinking of κ-carrageenan. The results of this study would be beneficial in understanding the radiation-induced changes in the structure and properties at different irradiation conditions, which may pave the way for various applications of carrageenan-based materials.

Performance Characterization of Dosimeters Based on Radiation-Hard Silicon Diodes in Gamma Radiation Processing

The dosimetric response of silicon diodes produced with distinct engineering technologies, Magnetic Czochralski (MCz), and standard Float Zone (Fz), has been investigated, aiming at their use for online dosimeters in gamma radiation processing applications. The p+-n-n+ junction diodes, 300 µm thick with an active area of 25 mm2, are operated as online radiation dosimeters in the short-circuit current mode. In this case, the key dosimetric quantity is the dose rate, which is correlated with the output current from the diode subjected to radiation. Thus, the dose is obtained offline by the integration of the corresponding current signal. The irradiations are performed with an industrial Gammacell 60Co facility at 2.3–2.44 kGy/h covering doses up to 275 kGy. Under continuous irradiation, both diodes delivered current signals whose intensities decreased with accumulated doses. Mitigation of this decay has been accomplished by pre-irradiating the devices to 700 kGy. Polynomial functions best represent the dose responses for either pristine or preirradiated diodes. The relevant dosimetric parameters as response stability, charge sensitivity, and repeatability of current signals (&amp;lt;5%) reveal the better performance of the MCz diode. It is important to note that the whole dataset fully complies with the international standard protocols for routine dosimeters in radiation processing dosimetry. Regarding radiation damage, which in unbiased diodes manifests primarily in the decay of current sensitivity, the results also showed greater tolerance of the MCz diode. Based on these studies, large availability, and better cost-effectiveness, it is possible to endorse the potential use of MCz devices as online routine dosimeters in radiation processing applications. However, the data reproducibility with the accumulated dose, the dose lifespan, and the effect of the irradiation conditions (e.g., temperature, relative humidity, and dose fractionating) remain to be investigated. Works in this direction are currently in progress.

Development of fluorescein-based dosimeter for radiation processing applications

Dosimetry forms an inseparable part of radiation processing. Many dosimeters are available to cover wide range of doses used in radiation processing. These include the Fricke, ceric-cerous, alanine ESR Alanine (Electron Spin Resonance Technique), dichromate, and radiochromic films. Low-dose radiation processing applications (&lt;2 kGy) such as insect disinfestation, shelf-life extension, and sprout inhibition use imported dosimeters. At present, radiochromic films/waveguides are used for low-dose applications; however, the dosimeters are costly and subject to sanctions and supply restrictions from country of origin. The present work discusses the development of system that can be used as a routine dosimeter for radiation processing facilities in the dose range of 200–2500 Gy. Iodine is generated by the action of radiolysis products of water on iodide and iodate present. Generated iodine halogenates fluorescein to erythrosine with the help of bicarbonate. Increase in absorbance due to the formation of erythrosine can be related to the absorbed dose and used in routine dosimetric applications. As the change is radiochromic, it advantageously provides a visual indication of dose received.

Radiation Induced Decoloration of Reactive Dye in PVA Films for Film Dosimetry

The investigation of film dosimeters made from polyvinyl alcohol (PVA) films dyed with methyl orange (MO) to enable their use in high dose radiation processing applications was studied. The dosimetric change in these films at pre and post irradiation was studied spectrophotometrically. Radiolytic bleaching was observed in PVA aided films exposed with Cs137 γ-source in dose range of 100-200kGy. The effects of pH, dye concentration and film thickness on the radiation response of the film dosimeters were discussed. The stability of MO-PVA films before and after exposure of radiation was also examined at ambient temperature and was found to be higher for long times at pre and post irradiation stages.

Comparative evaluation of the performance of thin diodes used as on-line dosimeters in radiation processing applications

In this work, we report a comparison between the performance of two samples of commercial PIN photodiodes (SFH206K from Osram and S2506-04 from Hamamatsu) mainly addressing the variation of their current sensitivities with accumulated dose ranging from 0-15 kGy. All the results so far obtained have revealed that the radiation induced currents are linearly dependent on dose rates from 3.65 to 55.64 Gy/h. The current sensitivity of both unirradiated diodes (0.178 nA.h/Gy.mm3) slightly decreases with accumulated dose, namely 0.32%/kGy (SFH206K) and 1.4%/kGy (S2506-04). Although the SFH206K device compares favorably with the S2506-04, both diodes can be considered as a low budge alternative, good enough for on-line dosimetry applications in the field of radiation processing.

Practical aspects of the application of radiation processing of raw milk

The use of modern technology for food processing by ionizing radiation is due to their high efficiency to reduce microbiological contamination. The purpose of the research was to study the effect of different doses of ionizing radiation when processing raw (unpasteurized) cow’s milk of different fat content (2.5% and 3.2%) in various media (air, carbon dioxide) on milk freshness indicators. The studies have been carried out in accordance with the requirements of GOST R 52054-2003 and TR TS 033/2013. Raw (unpasteurized) cow’s milk treated with doses of up to 2.2 kGy and 2.4 kGy in air and carbon dioxide, respectively, refers to fresh milk with lower quantitative characteristics of titratable acidity, content of malon dialdehyde (MDA), and microbiological parameters when treated with ionizing radiation in carbon dioxide gas. No significant differences have been found for titratable acidity and malon dialdehyde content depending on milk fat content, however, titrated acidity and malon dialdehyde content in milk with 2.5% fat have lower quantitative indicators compared to milk with 3.2% fat content. The determination of rational doses of ionizing radiation is of practical importance to ensure that the freshness indicators of raw (unpasteurized) cow’s milk processed with ionizing radiation meet the requirements of regulatory documents. The following doses of ionizing radiation are recommended: for the milk of the highest and first grade when processed with radiation in the air medium—a dose of 1.2 kGy and for milk of the second grade—a dose of 2.0 kGy, for radiation processing in a carbon dioxide medium—1.4 kGy and 2.2 kGy, respectively.

Determination of a consensus scaling factor to convert a Co-60-based alanine dose reading to yield the dose delivered in a high energy electron beam

An analysis of the published literature has been carried out to determine a consensus value for the scaling factor required to convert a dose determination using alanine based on a Co-60 calibration to yield the dose delivered in a high energy electron beam (≥6 MeV incident). Published data from the last 15 years were reviewed and combined to give a single, average, scaling factor. In carrying out this analysis, no attempt was made to deconstruct each experiment. The final results of each investigation were used as a coherent ensemble of independent determinations, irrespective of method or alanine dosimeter supplier. Experimental and Monte Calculations were considered separately and only the experimental data was used to determine the scaling factor.The results from six investigations were found to be consistent within their uncertainties and an overall conversion factor of 1.014 (standard uncertainty = 0.5%) was obtained. To be explicit, alanine dose readings determined from a Co-60 alanine calibration should be multiplied by this factor to yield the dose delivered in an electron beam.This scaling factor represents the consensus recommendations of the National Research Council, the National Institute for Standards and Technology, the Technical University of Denmark and the National Physical Laboratory for electron beams (≥6 MeV incident) used in radiation processing applications. By adopting a common factor, it is hoped to improve the consistency of dosimetry at industrial dose levels using high-energy electron beams.

Current response stability of a commercial PIN photodiode for low dose radiation processing applications

This work investigates the on-line response of a thin diode, for monitoring low dose radiation processing, with respect to the linearity between current and dose-rate, the most interesting part being the variation of the current sensitivity with the accumulated dose. The results obtained indicate that the current response of this diode is linear and quite stable with repeatability better than 0.2% and a slight decay of 5% of the current sensitivity (0.28 nA h/Gy) for doses up to 15 kGy. In an attempt to give theoretical support to these results, the radiation induced current is calculated as a function of the dose rate assuming the diode to be thin as compared with the standard values of the minority carrier diffusion lengths in intrinsic silicon. Agreement within 2% is found between calculations and experimental data.

A comparison between rad-hard float zone silicon diodes as gamma dosimeter in radiation processing

In this work, we report on the results obtained with rad-hard Standard Float Zone (STFZ) and Diffused Oxygenated Float Zone (DOFZ) silicon diodes in radiation processing dosimetry. The dosimetric probes were designed to operate in the direct current mode, as on-line radiation dosimeter. The irradiation of the samples was performed using a 60Co source with a dose rate of almost 2.4 kGy/h. The current response of each diode was measured as a function of the exposure time in steps from 5 kGy up to 50 kGy to achieve a total absorbed dose of 275 kGy. In this dose range it is observed a significant decrease in the photocurrent generated in both devices due to gamma radiation defects produced in their active volumes. To mitigate this effect, the samples were pre-irradiated with Co-60 gamma rays at 700 kGy. Despite of being less sensitive, these devices presented stable and reproducible current signals with a relative sensitivity decrease of about 19% within the whole range of dose studied. The dose-response curves of the pre-irradiated diodes showed quadratic behavior with correlation coefficient higher than 0.9999 for total absorbed dose up to 275 kGy. The comparison of the FZ and DOFZ responses evidenced that the latter was slightly superior to the first. However, it is important to note that all pre-irradiated diodes can be used as gamma dosimeters in radiation processing applications.

Effects of the addition of MWCNT and ZrO2 nanoparticles on the dosimetric properties of PVDF

The industrial application of radiation processing involves high doses of gamma or electron radiation to cause structural changes in materials, such as rubber vulcanization and polymer degradation, among others. A reliable dosimetric system is necessary to guarantee the desired effects and also to avoid damages. Poly(vinylidene fluoride) [PVDF] homopolymer has been recently proposed for application in high gamma dose dosimetry. In this work, nanocomposites made of PVDF filled with zirconium oxide [ZrO2] nanoparticles and multiwalled carbon nanotubes [MWCNT] were studied for applications in high dose dosimetry, for doses ranging from 100.0 kG to 2.72 MGy. Pristine PVDF and PVDF/MWCNT-ZrO2 samples were exposed to a Co-60 source. FTIR spectra were collected 2 h, 30 and 60 days after exposure. The intensity of the radio-induced absorption bands centered at 1715 cm−1 and 1730 cm−1 were found to have an unambiguous relationship with the absorbed dose. The pristine PVDF samples show linear behavior in the dose range between 100 and 1000 kGy. However, the PVDF/MWCNT-ZrO2 samples show linearity in a larger range, i.e. between 500 and 2750 kGy interval. The melting latent heat, measured by Differential Scanning Calorimetry (DSC) and SEM micrographs revealed that PVDF/MWCNT-ZrO2 samples show increased resistance to the radio-induced damages, when compared to pure PVDF samples irradiated in the same conditions. The results indicate that the MWCNT-ZrO2 adds resistance to PVDF and improves its dosimetric properties.

Dimethyl phthalate (DMP) degradation in aqueous solution by gamma-irradiation/H2O2

This work includes the applications of radiation processing to decompose dimethyl phthalate (DMP) with gamma and gamma/H2O2 processes. Changes in amounts of DMP, dissolved oxygen, total acidity and formaldehyde with irradiation dose were followed. The qualitative analysis of the DMP and the intermediates were determined by using a gas chromatography combined to mass spectrometry and ion chromatography. The results indicated that degradation rate of DMP was affected by H2O2 concentration, irradiation dose and removal efficiency of 25 mg L−1 DMP can reach 100% for 1.42 kGy irradiation dose in the concentration of 4.8 mM H2O2, respectively.

Irradiation Preservation of Meat and Meat Products and its Effect-A Review

Radiation processing is one of the emerging technologies to ensure the safety of meat and meat products. Microbial contamination of meat is a serious concern for both meat products and consumers. Irradiation has emerged as an alternate technology to eliminate microbial contamination and several countries have approved it. Wide acceptability of radiation processed meat products will depend upon quality parameters such as oxidative changes and organoleptic attributes. Food irradiation can cause changes in both macro and micro nutrients, but these changes are small. Irradiation is not alone in its ability to produce nutritional changes. Many food processes, notably cooking and heating in general, also cause nutrient loss, often to a greater run. No significant effects on essential amino acids have been observed in beef, fish or many other food stuffs even at sterilizing doses. Irradiation affects flavour and texture of dairy products and eggs. On the whole irradiation of food does not cause nutrient losses to the extent that there could be an adverse effect on the nutritional status of the individuals consuming these foods. Development of shelf stable meat and meat products is a challenging task due to physico-chemical, microbiological and sensory alterations during storage. Lot of thrust is being given in the application of radiation processing in meat sector due to its microbial safety. Maintaining and delivering quality and safety products both in civilian and service sectors is the need of the hour. Even though irradiation can ensure complete microbial sterility it can lead to lipid and protein oxidation due to the formation of free radicals which can cause flavour changes. The adverse implications due to lipid and protein oxidation being observed in meat, poultry products can be suppressed by selecting proper natural antioxidant combinations. Irradiation can be employed as a critical control point in the meat, poultry chain and such an intervention is essential in ensuring the safety of products.

Ionizing radiation processing and its potential in advancing biorefining and nanocellulose composite materials manufacturing

Nanocellulose is a high value material that has gained increasing attention because of its high strength, stiffness, unique photonic and piezoelectric properties, high stability and uniform structure. Through utilization of a biorefinery concept, nanocellulose can be produced in large volumes from wood at relatively low cost via ionizing radiation processing. Ionizing radiation causes significant break down of the polysaccharide and leads to the production of potentially useful gaseous products such as H2 and CO. The application of radiation processing to the production of nanocellulose from woody and non-wood sources, such as field grasses, bio-refining by-products, industrial pulp waste, and agricultural surplus materials remains an open field, ripe for innovation and application. Elucidating the mechanisms of the radiolytic decomposition of cellulose and the mass generation of nanocellulose by radiation processing is key to tapping into this source of nanocelluose for the growth of nanocellulostic-product development. More importantly, understanding the structural break-up of the cell walls as a function of radiation exposure is a key goal and only through careful, detailed characterization and dimensional metrology can this be achieved at the level of detail that is needed to further the growth of large scale radiation processing of plant materials. This work is resulting from strong collaborations between NIST and its academic partners who are pursuing the unique demonstration of applied ionizing radiation processing to plant materials as well as the development of manufacturing metrology for novel nanomaterials.

International Nuclear Science and Technology Conference 2016

ConferenceNuclear technology has played an important role in many aspects of our lives, including agriculture, medicine and healthcare, materials, environment, forensics, energy, and frontier advancement. The International Nuclear Science and Technology Conference (INST) aims to bring together scientists, engineers, academics and students to share knowledge and experiences about all aspects of nuclear sciences.INST2016 was the second of the INST conference series organized by Thailand Institute of Nuclear Technology. INST has evolved from a national conference series on nuclear science and technology that was held every two years in Bangkok for over a twenty-year period.INST2016 was held from 4 - 6 August 2016 in Bangkok, Thailand, under the central theme “Nuclear for Better Life”. The conference working language was English. The oral and poster research presentations covered seven major topics:• Nuclear physics and engineering (PHY)• Nuclear and radiation safety (SAF)• Medical and nutritional applications (MED)• Environmental applications (ENV)• Radiation processing and industrial applications (IND)• Agriculture and food applications (AGR)• Instrumentation and other related topics (INS)The welcome addresses, committees, program of the conference and the list of presentations can be found in the PDF.

Radiation Processing: An Emerging Preservation Technique for Meat and Meat Products

&lt;p&gt;Development of shelf stable meat and meat products is a challenging task due to physico-chemical, microbiological and sensory alterations during storage. Lot of thrust is being given in the application of radiation processing in meat sector due to its microbial safety. Maintaining and delivering quality and safety products both in civilian and service sectors is the need of the hour. Even though irradiation can ensure complete microbial sterility it can lead to lipid and protein oxidation due to the formation of free radicals which can cause flavour changes. Several studies on the usage of natural antioxidants which can arrest these changes have been reported. Irradiation can find excellent applications in the extension of shelf life of chilled and non chilled carcasses and birds in service sectors. There are several radiation processing plants in India commissioned in the private sector which can also be utilized by Armed forces for extending the shelf life of whole carcass and birds with an extension of shelf life. This will be of great&lt;strong&gt; &lt;/strong&gt;significance to the defence forces.&lt;/p&gt;&lt;p&gt;&lt;strong&gt; &lt;/strong&gt;&lt;/p&gt;