Thermal neutron cross section and resonance integral of the reaction of135Cs(n,γ)136Cs: Fundamental data for the transmutation of nuclear waste

To determine the cross sections of the¹³⁵Cs(n,γ)¹³⁶Cs reaction, a sample of¹³⁵Cs included in a “standardized solution” of¹³⁷Cs was used as a target and irradiated in a reactor. The ratio of the atom number of¹³⁵Cs to that of¹³⁷Cs was determined to be 0.89±0.03 with a quadrupole mass spectrometer. The thermal cross section and the resonance integral measured in this study were determined to be 8.3±0.3 and 38.1±2.6 b respectively.     

Determination of 135Cs in nuclear power plant wastes by ICP-MS and k 0-NAA

A radiochemical method for the determination of ¹³⁵Cs in radioactive wastes has been adopted/developed. For the separation of cesium from other elements ammonium-molybdophosphate precipitation and cation exchange chromatography were used. The chemical yield of the method was about 60–100 %. ¹³⁵Cs was measured by two methods. In neutron activation analysis (NAA), Cs was irradiated with reactor neutrons. ¹³⁶Cs was detected by gamma spectrometry, wherefrom the activity/mass of ¹³⁵Cs was calculated according to the k ₀-standardization technique. The Cs containing fractions were measured by inductive coupled plasma mass spectrometry, as well. NAA and ICP-MS techniques were comparatively evaluated and a good agreement between the results was found. The activity concentration of ¹³⁵Cs in a couple of waste samples originating from VVER-440 type nuclear reactors was in the range of 1–5 Bq L^?1 (20–120 ng L^?1) while ¹³⁷Cs activity concentrations varied between 0.1 and 1 MBq L^?1.     

The development of radioactive glass surrogates for fallout debris

The production of glass that emulates fallout is desired by the nuclear forensics community for training and measurement exercises. The composition of nuclear fallout is complex, with widely varying isotopic compositions (Fahey et al., Proc Natl Acad Sci USA 107(47):20207–20212, 2010; Bellucci et al., Anal Chem 85:7588–7593, 2013; Wallace et al., J Radioanal Nucl Chem, 2013; Belloni et al., J Environ Radioact 102:852–862, 2011; Freiling, Science 139:1058–1059, 1963; Science 133:1991–1999, 1961; Bunney and Sam Government Report: Naval Ordinance Laboratory, White Oak, 1971). As the gaseous cloud traverses from hotter to cooler regions of the atmosphere, the processes of condensation and nucleation entrain environmental materials, vaporized nuclear materials and fission products. The elemental and isotopic composition of the fission products is altered due to chemical fractionation (i.e. the fission product composition that would be expected from fission of the original nuclear material is altered by differences in condensation rates of the elements); the fallout may be enriched or depleted in volatile or refractory fission products. This paper describes preliminary work to synthesize, irradiate and fractionate the fission product content of irradiated particulate glass using a thermal distillation 2 h after irradiation. The glass was synthesized using a solution-based polymerization of tetraethyl orthosilicate. (Izrael, Radioactive fallout after nuclear explosions and accidents, 2002) Uranium was incorporated into the glass particulate at trace concentrations during polymerization. The particulate was subjected to a short thermal neutron irradiation then heated to 1,273 K approximately 2 h after the end of irradiation. Fission products of ^{133, 134, 135}I, ^{132, 134}Te, ¹³⁵Xe, ¹³⁸Cs and ^{91, 92}Sr were observed to be distilled from the particulate. The results of these preliminary studies are discussed.     

Gas phase thermolysis of allylphosphines,kinetic study

Diallylphenyl, allylbenzylphenyl and allylmethylphenyl phosphines were pyrolized in a stirred-flow reactor at 380–429°C/7-20 torr, using toluene as carrier gas. The reaction products were propene, 1-phospha-1,3-butadiene, 1-phospha-1,2-diphenylethylene and 1-phosphaethylene. The phospha-alkenes formed evolve into cyclo addition products. The propene elimination reaction showed first-order kinetics with rate coefficients following the Arrhenius equations: Diallylphenylphosphine: k(s⁻¹) = 10^{10.57 ± 0.31} exp(-143 ± 4 kJ/mol.RT) Allylbenzylphenylphosphine: k(s⁻¹) = 10^{9.71 ± 0.47} exp(-135 ± 6 kJ/mol.RT) Allylbenzylphenylphosphine: k(s⁻¹) = 10^{9.61 ± 0.61} exp(-144 ± 9 kJ/mol.RT) A six-center cyclic transition state unimolecular reaction mechanism, consistent with the above Arrhenius parameters, is proposed for the propene elimination reaction.     

The neutron activation determination of lithium in the presence of alkali metals and magnesium

A neutron activation method for lithium in the presence of alkali metals or magnesium has been developed, utilizing the ⁶Li(n,α)³H and ¹⁶O(t,n)¹⁸F nuclear reactions. After a short thermal neutron irradiation with a. lithium standard, 112-min fluorine-18 is separated by a lead chlorofluoridc precipitation. The annihilation photons from the separated fluorine-18 are counted using 2 sodium iodide detectors, a fast-slow coincidence system and a multichannel analyzer. Precision in a synthetic l% lithium-in-sodium matrix was found to be ± 2.0% standard deviation, whereas the accuracy of the method is estimated to be ± 3% or better. The ultimate sensitivity in pure solution is estimated to be about 0.2 p.p.b. and in a sodium matrix about 0.5 p.p.m. The only interferences are several positron emitters, easily discriminated from by chemical separation, decay or by means of other nuclear parameters. Three hours are required for a duplicate determination, following initial sample preparation and dilution. To use the method, the lithium isotopic abundance must be known or determined by mass spectrometry because of the prevalence of depleted litliium in metal and salts.     

Industrial production and purification of <Superscript>32</Superscript>P by sulfur irradiation with partially moderated neutron fluxes and target melting

Target purification of S_α is carried out by distillation at 444±2 °C under N atmosphere and diluting the vapors in CS₂. The solution is filtered through fiberglass, Teflon and cellulose to obtain S_α by CS₂ evaporation. Once 30 g of this target are irradiated with fast neutron fluxes from 4.5 to 7.4·10¹² n·cm⁻²s⁻¹ from 6 to 12 hours, the nuclear reaction ³²S(n,p)³²P takes place. So, the irradiated S_α sample is placed in a Pyrex container situated inside a furnace as the most important piece of equipment in one aluminum and Lucite glove box. The distillation of irradiated sulfur takes place at 444±2 °C under N atmosphere during 1–2 hours. The vapors are connected to a sulfur diluter containing 20% CS₂ aqueous solution, followed by an activated carbon filter and the two similar additional sulfur diluters. Once cooled, the distillation chamber keeps the radioactive, carrier-free ³²P stuck to the wall. Then 25–50 ml of 0.1N HCl acid was injected by suction and heated again at 110±2 °C during 1 hour. The corresponding chemical reaction takes place and the labeled H₃ ³²PO₄ solution is produced. In such a way, industrial production of ³²P labeled molecules has started in Mexico, with an initial production of 3700–5550 MBq per week.     

Preparation and evaluation of two 188Re-radiopharmaceuticals for endovascular irradiation

Procedures for complexing DTPA with ¹⁸⁸Re from a ready kit and by conventional manipulation were elaborated and the study of the stability and biodistribution of ¹⁸⁸Re perrhenate and ¹⁸⁸Re-DTPA were performed. Best labeling was achieved using DTPA (38 mM) with 2 mg/ml of SnCl₂ ·2H₂O. The radiochemical purity was 95.9±2.9%. The complex was stable for 24 hours when ascorbic acid was used. Greatest uptake of ¹⁸⁸Re-DTPA was by kidneys (19.3±2.1%ID/g) and for ¹⁸⁸Re-perrhenate by stomach (21.3±2.8%ID/g). In conclusion a kit of freeze-dried DTPA was developed. Organ damage is unlikely by virtue of its rapid urinary excretion. This revised version was published online in July 2006 with corrections to the Cover Date.     

Application of instrumental radioanalytical techniques to nuclear waste testing and characterization

This paper describes the validation of a multi-technique analytical methodology that uses inductively coupled plasma-mass spectrometry, α-spectrometry, and γ-spectrometry for the routine analysis of samples containing transuranic radionuclides. This methodology is capable of the determination of concentrations of both²³⁸Pu and²⁴¹Pu in the presence of²³⁸U and²⁴¹Am without the need for chemical separations. The relative merits of these three techniques were evaluated as they are applied in a nuclear waste material and spent nuclear fuel testing program by analytical (1) standards and (2) solutions prepared from the dissolution of glasses doped with²³⁷Np,²³⁹Pu, and²⁴¹Am. The uncertainty associated with technique was within ±4% for standards and ±10% for doped nuclear waste glasses. The methodology was then used to analyze three fully radioactive waste glasses.     

Reactions of the fluorobromocarbene radical studied by laser-induced fluorescence

CFBr radicals produced by the reaction of atomic oxygen with F₂CCFBr were monitored in a discharge flow system by fluorescence excited at 424 nm. The rate coefficients for reactions of the CFBr radicals were measured between 298 and 358 K, and the following values were obtained in units of cm³/molec·s: O₂ < 2 × 10^?16 at 353 K; NO < 10^?14 at 298 K; F₂CCFBr < 10^?15 at 298 K; Cl₂ (1.9 ± 0.6) × 10^?12 exp(?762 ± 92/T) Br₂ (1.4 ± 0.3) × 10^?12 exp(?533 ± 62/T).     

Distribution of 131I, 134Cs, 137Cs and 239,240Pu concentrations in Korean rainwater after the Fukushima nuclear power plant accident

Radionuclides such as ¹³¹I, ¹³⁴Cs, ¹³⁷Cs, and ^239,240Pu in Korean rainwater have been analyzed by Korea Research Institute of Standards and Science (KRISS) since the Fukushima nuclear power plant accident in March 2011 to investigate the activity level, distribution pattern, and temporal variation and to assess the radiation dose the public is exposed to. The concentration of ¹³¹I in the Korean rainwater samples varied between 0.033 (minimum detectable activity; MDA) and 1.30 Bq kg^?1 and the concentrations tended to decrease exponentially with time. The concentrations of ¹³⁴Cs and ¹³⁷Cs in rainwater ranged from 0.01 to 334 ± 74 and 0.29 ± 0.01 to 276 ± 1 mBq kg^?1, respectively. The mean activity ratio of ¹³⁷Cs/¹³⁴Cs in the rainwater samples collected from April 18 to May 12 was estimated to be 0.44 ± 0.21, and this value is lower than that (ca. 1) observed in Fukushima, Japan, when there was an escape from the nuclear reactors. When an attempt was made to analyze Pu isotopes in rainwater samples, no Pu isotopes were detected above the MDA in any of the rainwater samples. Although the locations investigated were different from Asia to Europe, the concentrations of ¹³¹I, ¹³⁴Cs and ¹³⁷Cs in the rainwater are comparable, which suggests a global contamination of ¹³¹I, ¹³⁴Cs, and ¹³⁷Cs occurred because of the Fukushima nuclear power plant accident.     

The isotopic composition and atomic weight of molybdenum

The isotopic composition of molybdenum in a shelf reagent standard (MoO₃, 99.99%), 13 molybdenites, and three iron meteorites has been determined with a thermal ionization mass spectrometer. No especially-evident variations of molybdenum isotopes among these samples have been found. The mass fractionation of molybdenum occurring in isotopes during the measurements is discussed and our preferred natural abundances of molybdenum isotopes are:⁹²Mo, 14.7287 ± 0.0010;⁹⁴Mo, 9.2118 ± 0.0006;⁹⁵Mo, 15.8935 ± 0.0011;⁹⁶Mo, 16.6731 ± 0.0011;⁹⁷Mo, 9.5692 ± 0.0007;⁹⁸Mo, 24.2289 ± 0.0017;¹⁰⁰Mo, 9.6950 ± 0.0007. Thus, the atomic weight of molybdenum is 95.9415 ± 0.0001 (the value currently accepted by IUPAC [IUPAC Inorganic Chemistry Division, Pure Appl. Chem., 63 (1991) 991] is 95.94 ± 0.01). The uncertainties correspond to the 95% confidence limit calculated from all the terrestrial and meteoritic samples.     

Development of a SIMS Method for Isotopic Measurements in Nuclear Forensic Applications

 Methodologies based on secondary ion mass spectrometry (SIMS) for isotopic measurements in nuclear forensic applications relevant to the age determination of Pu particles and isotopic composition of oxygen for geolocation assignment are described. For the age determination of Pu particles, a relative sensitivity factor (RSF) to correct for the different ionisation efficiencies of U and Pu, was obtained by analysing standard Pu materials with known ages. An RSF of 2.41±0.05 was obtained for PuO₂ from measurements on samples with different Pu/U ratios. In a sample of known origin, using this RSF value, the age calculated from the ²³⁸Pu/²³⁴U and ²⁴⁰Pu/²³⁶U ratios agreed well with the reported age of 2.3 years. For geolocation assignment, a new approach based on the measurement of differences in the natural abundance of ¹⁸O and ¹⁶O isotopes and their ratio was developed. The instrumental mass discrimination of the ¹⁸O/¹⁶O ratio was determined using three O-isotope samples of different chemical composition. The measured precision (the standard error of 100 cycles/analysis) obtained for the oxygen isotopic measurement on the samples was typically ±1.1‰.     

Conformational enthalpy and volume changes in bromocyclohoexane determined by Raman spectroscopy

Raman spectra of bromocyclohexane have been recorded as a function of temperature between 22 and 135°C and as a function of pressure from 1 bar to 7.0 kbar. The integrated intensities of the bands at 657 and 687 cm⁻¹ have been used to monitor the relative populations of the axialand equatorial forms respectively. From these data, enthalpy and volume differences of 1.1 ± 0.3 kJ mol⁻¹ and −2.2 ± 0.3 cm³ mol⁻¹ respectively were determined for the equatorial—axial equilibrium.     

Effect of the natural radioactivity concentrations and 226Ra/238U disequilibrium on cancer diseases in Penang,Malaysia

Natural radioactivity measurements and assessment of radiological hazards in soil and sand samples obtained from Penang, Malaysia were carried out using the Exploranium GR-135 Plus “Identifier” Radioisotope Identification Device and high-resolution High Purity Germanium (HPGe) detector system. The activity concentrations of ²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K were found to be 184±11, 396±22, 165±14, and 835±28 Bq kg^?1 respectively, and the external gamma dose rate is 315±44 nGy h^?1 for soil samples. For sand samples, the activity concentrations of ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K were 31±8, 62±16, 36±6, and 369±17 Bq kg^?1, respectively, and the external gamma dose rate is 66±12 nGy h^?1. To assess the radiological hazard of radioactivity present in the samples, the radium equivalent activity, annual effective dose, annual gonadal dose equivalent, external hazard, and internal indices were calculated.The Ra_eq values of soil samples were higher than the limit of 370 Bq kg^?1, which is equivalent to a gamma dose of 1.5 mSv yr^?1, whereas the Ra_eq for sand samples was lower than 370 Bq kg^?1. The calculated concentrations by HPGe spectroscopy were compared with the measured concentrations detected by a GR-135 spectrometer. The calculated and measured gamma dose rates had an ideal correlation coefficient R of 0.72. The gamma dose rates in Penang increased with the average annual age-standardized rates (ASR) for all cancers between 1994 and 2010. The effects of the pH value of soil and sand samples on natural radionuclides concentrations were investigated. The high concentration of ²²⁶Ra/²³⁸U ratio disequilibrium (²²⁶Ra/²³⁸U of 1.76–2.33) was observed in the sampling sites. Moreover, a portable continuous radon monitor (SNC, model 1029, Sun Nuclear Corporation) was used to measure the radon concentration of the soil surface. The radon concentrations were found to vary from 7 to 50 Bq m^?3. A positive correlation was observed between the radon and radium concentrations in samples measured by the SNC continuous radon monitor and HPGe detector.     

A 15N nuclear magnetic resonance study of the base-catalyzed NH2 exchange reactions of acetamide and thioacetamide

The base-catalyzed ? NH₂ exchange reactions of acetamide and thioacetamide were studied by ¹⁵N nuclear magnetic resonance spectroscopy by the use of line-shape analysis. The ¹⁵N NMR spectra of these primary amides at intermediate exchange rates were broad doublets, which indicated that the two amide protons were exchanging at different rates. The line-shape analysis indicated that the ratio of exchange rates was 6±1 for acetamide and 3±1 for thioacetamide.     

Cross section measurements for 141Pr(n,γ)142Pr reaction at neutron energies from 13.5 to 14.8?MeV

Activation cross-sections were measured for the ¹⁴¹Pr(n,??)¹⁴²Pr reaction at three different neutron energies from 13.5 to 14.8?MeV. The fast neutrons were produced via the ³H(d,n)⁴He reaction on Pd-300 neutron generator. The natural high-purity Pr₂O₃ powder was used as target material. Induced gamma activities were measured by a high-resolution gamma-ray spectrometer with high-purity germanium detector. Measurements were corrected for gamma-ray attenuations, random coincidence (pile-up), dead time and fluctuation of neutron flux. The neutron fluences were determined by the cross section of ²⁷Al(n,??)²⁴Na reaction. The neutron energy in the measurement were by the cross section ratios of ⁹⁰Zr(n,2n)^89m+gZr and ⁹³Nb(n,2n)^92mNb reactions. The data for ¹⁴¹Pr(n,??)¹⁴²Pr reaction cross sections are reported to be 3.3?±?0.2, 2.7?±?0.2 and 2.2?±?0.2 mb at 13.5?±?0.2, 14.1?±?0.2, and 14.8?±?0.2?MeV incident neutron energies, respectively. Results were discussed and compared with some corresponding values found in the literature.     

Degradation of chlorpyrifos by ionizing radiation

Summary A survey was carried out to determine radioactivity concentrations and associated dose rates from the naturally occurring nuclides ²³² Th, ²³⁸U and ⁴⁰K in various surface soil formations of Alhkraje city. Samples were collected from different areas of the study, sieved through a fine mesh, sealed in 0.5-liter plastic Marinelli beaker, and measured in the laboratory for 24 hours each. From the measured g-ray spectra, radioactivity concentrations were determined for ²³² Th ranging from 5.32±2.59 to 16.40±2.04 Bq ^. kg^-1, ²³⁸U (2.87±0.18 to 18.83±0.81 Bq ^. kg^-1), ⁴⁰K (211.33±55.04 to 378.97±36.46 Bq ^. kg^-1) and ¹³⁷Cs (0 to 3.19±1.02 Bq ^. kg^-1). Absorbed dose rates in air doors were calculated to be in the range of 15.29±2.65 to 30.00±3.24 nGy ^. h^-1, the corresponding effective dose rates per person outdoors were estimated to be between 21.00±0.95 to 36.83±2.11 mSν^. y^-1, assuming a 20% occupancy factor.     

Rate constants for the gas‐phase reactions of a series of C3?C6 aldehydes with OH and NO3 radicals

By using relative rate methods, rate constants for the gas‐phase reactions of OH and NO₃ radicals with propanal, butanal, pentanal, and hexanal have been measured at 296 ± 2 K and atmospheric pressure of air. By using methyl vinyl ketone as the reference compound, the rate constants obtained for the OH radical reactions (in units of 10⁻¹² cm³ molecule⁻¹ s⁻¹) were propanal, 20.2 ± 1.4; butanal, 24.7 ± 1.5; pentanal, 29.9 ± 1.9; and hexanal, 31.7 ± 1.5. By using methacrolein and 1‐butene as the reference compounds, the rate constants obtained for the NO₃ radical reactions (in units of 10⁻¹⁵ cm³ molecule⁻¹ s⁻¹) were propanal, 7.1 ± 0.4; butanal, 11.2 ± 1.5; pentanal, 14.1 ± 1.6; and hexanal, 14.9 ± 1.3. The dominant tropospheric loss process for the aldehydes studied here is calculated to be by reaction with the OH radical, with calculated lifetimes of a few hours during daytime. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 79–84, 2000     

Reactions of CFBr studied by laser-induced fluorescence

Laser-induced fluorescence has been used to study reactions of CFBr radicals in a discharge-flow system. Arrhenius expressions of (1.9 ± 0.6) ξ 10^?12 exp(?762± 92/T) and (1.4 ± 0.3) ξ 10^?12 exp(?533 ± 62/T) cm³ molecule ^?1s^?1 for their reactions with Cl₂ and Br₂ respectively. Upper limits were obtained for the rate of reaction of CFBr with O₂ and F₂CCFBr.     

Marine natural products: Deodactol,antineoplastic sesquiterpenoid from the sea hare aplysia dactylomela

Deodactol, a halogenated bisabolene-type sesquiterpene alcohol, has been isolated from the sea hare Aplysia dactylomela, and its structure and absolute configuration have been determined by X-ray diffraction. The compound crystallizes in the monoclinic system with the following crystal data: a=6.723(2), b = 11.838(1), c= 10.962(2) Å, β=99.41(2)°, V= 860.7; ?x= 1.669 g cm^?3 at ?135±2°C; space group P2₁. The structure was solved by the heavy-atom method from 3-dimensional diffractometer data collected at ?135±2°C using CuK_α radiation. The final R factor for 1854 reflections is 0.029. The absolute configuration of the molecule was determined by the “R Method” of Hamilton. Deodactol has a strong intramolecular OHO hydrogen bond bridging its tetrahydropyranyl and cyclohexanol rings. The alcohol shows moderate cytotoxic activity. The absolute configuration of deodactol corresponds to that of several halogenated chamigrenes and supports the proposed biogenetic hypothesis linking halogenated bisabolenes and chamigrenes.