Accumulation and discharge behavior of Cs-137 by zebra fish (Brachydanio rerio) in different aquatic environments

The uptake and release kinetics of137Cs from water by the tropical fishBrachydanio rerio has been studied under controlled laboratory condition. The accumulation of this radionuclide from food was avoided by feeding the fishes separately in an inactive environment. A steep inverse dependence of bioconcentration factor (BCF) with potassium concentration has been observed. This can formally be described by the equation BCF=5.2 · [K+]−0.44. The elimination rate constant K in fresh water conditions has been found to have a magnitude of 0.014±0.03 d−1 which corresponds to a biological half-life of 51±10 days. The uptake and release kinetics ofBrachydanio rerio has been compared with earlier stud…

Mass Yields in the Very Asymmetric Fission of 249Cf(nth,f)

Independent fission yields and fragment kinetic energies in the very asymmetric (A=87−72) fission of 249Cf have been measured using the mass separator LOHENGRIN at the Institut Laue-Langevin in Grenoble. The mass yields were found to be up to a factor of 100 higher than predicted in the US ENDF-V file. A preliminary evaluation of the isotopic yields shows a strong increase of the proton odd-even effect from 7 % to 15 %. This can be explained by a decreasing excitation energy in this very asymmetric region.

Odd-Even Effects in the Reaction 241Am(2n,f)

Fission yields of the light fission products in the reaction 241Am(2n,f) have been measured. The results indicate an odd-even proton effect in the yield distribution of this odd nucleus with Z=95.

Mass and charge distributions in the very asymmetric mass region of the neutron induced fission of

Abstract The mass-separator Lohengrin was used to measure the yields of the light fission products with A=74−85 and their nuclear charge and kinetic energy distributions from the odd- Z compound nucleus 239 Np ∗ formed by double capture of thermal neutrons. The mass yield distribution reveals an influence of the fragment shell with N=50 affecting also the nuclear charge and kinetic energy distributions. An odd–even effect for protons is found in the very asymmetric mass division, increasing from 4% to 35% with increasing fission asymmetry. This is in contrast to findings in normal asymmetric fission (region of high fission yields) where no odd–even effect for protons was observed. An odd–ev…

Isomeric Yield Ratios of 134I and 136I and Independent Fractional Yields of some Halogen Isotopes in the Fission of 232Th with Reactor Neutrons

Status of independent yield measurements

Recent progress in the measurement of independent yields in low energy nuclear fission is presented. Different experimental approaches are discussed and a survey of the most important experimental results obtained is given. Physical consequences for the understanding of the fission process are briefly referred.

Determination of elemental levels in medicinally important Indian leaves by instrumental neutron activation analysis

Levels of As, Ba, Br, Ca, Ce, Cl, Cr, Cs, Eu, Fe, Hg, I, K, La, Mg, Mn, Na, Ni, Rb, Sb, Sc, Sm, Sr, Th, Zn, and U have been determined in ten leaves widely used in ayurvedic medicine by instrumental neutron activation analysis (INAA). The neutron irradiations were performed with a 100 kW Triga nuclear reactor and the induced activity was counted with a gamma-ray spectrometer. Based on elemental levels obtained the utility of these leaves in medicine are discussed.

Chlorine loss from polyvinylchloride under neutron irradiation

PVC samples were irradiated for 1 hour with a thermal neutron flux of Φ th =4.71·1011n·cm−2·s−1 and the chlorine lost during irradiation was measured by γ-ray spectrometry. About 15% of loss of chlorine has been observed for untreated samples while samples heated to temperatures of 60 and 80°C for one minute before irradiation have been found to loose about 8% and 3%, respectively. The results indicate an influence of the polymer structure on the release of chlorine.

Determination of phosphorus by instrumental neutron activation and bremsstrahlung measurement in bone samples

A non destructive method based on the31P(n,γ)32P reaction for the assay of phosphorus in bone samples is described. This method involves a thermal neutron irradiation of 2 minutes in a reactor followed by the measurement of the bremsstrahlung produced by the β− of32P in a Ge-detector surrounded by an anti-Compton shield. Accuracy and precision were tested by analysing the certified NIST 1486 Bone Meal reference material and tri-calcium phosphate (Ca3(PO4)2) samples. The value obtained for the reference material was in good agreement with the certified value and with relative standard deviation of 4.1% the precision was acceptable. The value obtained for Ca3(PO4)2 shows a deviation of −6% fr…

The discovery of nuclear fission 50 years ago a few remarks

Abstract  A historical account on the details of the discovery of nuclear fission in 1939 is given.

Uptake and release kinetics of134Cs by Goldfish (Carassius auratus) and137Cs by Zebra Fish (Brachydanio rerio) in controlled aquatic environment

The uptake and release kinetics of134Cs by Goldfish (Carassius auratus) and137Cs by Zebra Fish (Brachydanio rerio) from aquatic media of different ionic compositions and temperature was studied in controlled laboratory conditions. The accumulation of radiocesium in the case ofBrachydanio rerio is observed to be strongly dependent on the potassium ion concentration of the aquatic medium, but in the case ofCarassius auratus this dependence is quite weak. The biological half-lives of the cesium isotopes incorporated into the fish investigated in the present work vary from 19 to 80 days and are influenced by the temperature and the ionic composition of the aquatic medium.

Determination of macro, micro nutrient and trace element concentrations in Indian medicinal and vegetable leaves using instrumental neutron activation analysis

Abstract Leafy samples often used as medicine in the Indian Ayurvedic system and vegetables were analyzed for 20 elements (As, Ba, Br, Ca, Ce, Cr, Cs, Co, Eu, Fe, K, La, Na, Rb, Sb, Sc, Sm, Sr, Th, Zn) by employing Instrumental Neutron Activation Analysis (INAA). The samples were irradiated at the 100 kW TRIGA-MAINZ nuclear reactor and the induced activities were counted by gamma ray spectrometry using an efficiency calibrated high resolution High Purity Germanium (HPGe) detector. The concentration of the elements in the medicinal and vegetable leaves and their biological effects on human beings are discussed.

Test of multielement analysis of bone samples using instrumental neutron activation analysis (INAA) and anti-Compton spectrometry

INAA and anti-Compton spectrometry has been employed in the analysis of test bone samples. Validity and accuracy of the method were checked by the use of two biological reference materials procured from the National Institute of Standards and Technology, USA (NIST) and the International Atomic Energy Agency, Austria (IAEA). NIST 1486 Bone Meal (ca. 200–800 mg) and A-11 Milk Powder (ca. 200–600 mg) samples were irradiated in the 100 kW TRIGA Mainz reactor. Concentrations of 13 elements in both biological reference materials have been determined and were found in good agreement with the certified and provisional values.

Mass and charge distributions in the very asymmetric thermal neutron induced fission of the odd-Z nucleus 242mAm

Yields of light fission products (A = 68, 70-84, 87, 88, 94, 96, 98, 102 and 106-108), their kinetic energies and nuclear charge distributions (A = 71-84, 87 and 88) in the thermal neutron induced fission of the odd-Z nucleus Am-242m(Z = 95) were measured using the mass-separator Lohengrin at the Institute Laue-Langevin in Grenoble (France). The mass yield curve shows a fine structure at A = 70, probably due to shell and/or odd-even effects affecting also the nuclear charge distribution. The analysis of isotopic chain yields gives evidence for a very low excitation energy of the lightest fission fragments observed. A preferential formation of fragments with even Z is found for this odd-Z co…