Determination of alpha,beta, X-ray and gamma emitting radionuclides in reactor components and fuel assemblies from NPP V1 Jaslovske Bohunice

The radionuclides in reactor and fuel construction parts of the V1 Jaslovske Bohunice nuclear power plant (NPP V1) were identified and their activity was measured. Samples from reactor and fuel assemblies such as control rod connection rod, shielding/absorber parts of fuel rod, neutron in-core measurement channels, pressure vessel basic construction material and internal cladding, core barrel and protective tube unit were analyzed. Activity concentrations of ⁶⁰Co, ⁵⁵Fe, ^63,59Ni, ⁹⁰Sr, ⁹⁹Tc, ⁹³Mo, ⁹⁴Nb, transuranic elements were determined. Analytical and sampling methods are briefly described for the measured radionuclides. The presented results were used for characterization of the waste during the decommissioning of NPP V1 nuclear reactors.     

Radiochemical analysis of radionuclides difficult to measure for waste characterization in decommissioning of nuclear facilities

Some radiochemical analytical methods for the determination of important beta-radionuclides for decommissioning are presented. An analytical method is briefly described, which is used for the determination of ³H and ¹⁴C in steel and aluminum by combustion using commercial oxidizer. A leaching method was developed for the determination of ³H in the contaminated silica gel. A simple distillation method is presented for the determination of ¹⁴C in heavy water and wastewater sample. A method developed for the simultaneous determination of ³H, ¹⁴C, ³⁶Cl, ⁵⁵Fe, ⁶³Ni, ⁴¹Ca and ¹²⁹I in concrete, graphite, aluminium, lead, and steel is presented. The developed methods have been successfully used to analyse various materials for characterization of the waste during the decommissioning of Danish nuclear reactors.     

Determination of239, 240Pu in environmental samples from surroundings of the atomic power station Jaslovske Bohunice

The development of a rapid and reproducible method for the separation of plutonium from soil samples is described. Tetravalent plutonium is extracted from 8M HNO₃ into 30% Aliquat-336/toluene mixture. Uranium and thorium are removed with nitric and hydrochloric acid washes. Plutonium is backextracted with HCl–H₂C₂O₄ and HCl–HF solutions. Plutonium is coprecipitated with NdF₃ and filtrated onto a 0.1–0.2 m membrane filter to prepare a source for -spectrometry. The chemical yields of separation are about 50–60%.     

Intercomparison exercise on difficult to measure radionuclides in activated steel: statistical analysis of radioanalytical results and activation calculations

Journal of Radioanalytical and Nuclear Chemistry - This paper reports the results obtained during an intercomparison exercise for the determination of difficult to measure radionuclides in...     

Monitoring of the <Superscript>14</Superscript>C concentration in the stack air of the nuclear power plant VVER Jaslovske Bohunice

¹⁴C releases in the stack air of the NPPs V1 and V2, Jaslovske Bohunice was determined during the year 2004–2010. Radioactivity concentration of ¹⁴C in the stack air was determined in the forms of inorganic ¹⁴CO₂ and ¹⁴C _n H _m . The annual average activity concentration in the stacks air samples varies between 12 and 121 Bq m⁻³. NPP V1, starting with 45 Bq m⁻³ in 2005 is decreasing due to the shutting down of the reactors (the first reactor was shut down in December 2006 and the second reactor in December 2008). The average value of radioactivity concentration for power unit V2 was 32 Bq m⁻³ in 2004 and reached the value of 102 Bq m⁻³ in the first-quarter of the 2010. The average normalized yearly discharge rates were between 0.39 and 0.64 TBq GW_e⁻¹ year⁻¹ (2005–2008), NPP V1 and 0.19–0.61 TBq GW_e⁻¹ year⁻¹ (2004–first-quarter 2010) for NPP V2, Jaslovske Bohunice. Most of the discharged ¹⁴C is in a hydrocarbon form, (95% for Jaslovske Bohunice NPP V2), but the CO₂ fraction may reach 37% in the air stack for Jaslovske Bohunice V1.     

Concentrations and activity ratios of radionuclides around the nuclear facilities in Korea

The concentrations and activity ratios of the radionuclides aroundthe nuclear facilities located in Taejon were determined. The concentrationsand activity ratios of uranium isotopes in the downstream decreased with increasingdistances from the point of discharge and reached the reference value after4 km. The concentrations of uranium isotopes in the brook around LWR fuelfabrication facilities were lower than those in the downstream around HWRand LWR fuel fabrication facilities, while the activity ratios of ²³⁴U/²³⁸U in the brook were higher than those in the downstream.The concentrations of uranium isotopes in the ground water measured quarterlywere variable depending on the sampling time. The concentrations of the grossalpha of airborne particulates collected around the nuclear facilities werefound to be in the narrow range of 0.02 to 0.10 mBq/m³ with a meanvalue of 0.05 mBq/m 3 . Both the concentrations and activity ratios of ¹³⁷Cs, ^239,240Pu and ⁹⁰ Sr around the nuclearfacilities were not very different from the worldwide fallout. The concentrationsof uranium isotopes in the soil samples around the nuclear facilities werevery close to natural background levels.     

Monitoring of environmental radiation and radionuclides around nuclear fuel cycle facilities from 1989 to 1995

Aomori Prefectural Govemment and Japan Nuclear Fuel Limited started environmental radiation monitoring around Nuclear Fuel Cycle Facilities in April 1989. External radiation is measured by NaI(TI) scintillator and Themoluminescence dosimeter. The level of external radiation is relatively low in the winter due to snow. We have collected terrestrial samples of drinking water, soil, agricultural products and marine samples of seawater, sea sediment, seafood, etc. periodically. We have measured many radionuclides and fluoride in these samples. In soil sample,^239+240Pu ratio to¹³⁷Cs was almost constant at all sampling points. A correlation was observed between salinity and concentration of tritium, uranium and fluoride in lake water of Lake Obuchinuma. The correlation between¹³⁷Cs and^239+240Pu in lake sediment was observed in each lake.     

Determination of radioactive cobalt in mixtures of radionuclides

A detailed procedure for the separation of radioeobalt from other active material is described. Precipitation as the mercurithiocyanate and as the anthranilate have been compared, and the latter has been shown to be somewhat preferable.     

Determination of radionuclides in the environment using gamma-spectrometry

Summary Seventy nine samples, including soil and rock, were collected from the agrestic region of the State of Pernambuco, Brazil. The activity concentrations of ²³⁸U and ²²⁶Ra in the samples were determined by gamma-spectrometry using an HPGe detector. The concentrations of ²³⁸U were 22 Bq ^. kg^-1 to 22 kBq ^. kg^-1. The concentrations of ²²⁶Ra were 14 Bq ^. kg^-1 to 17 kBq ^. kg^-1. The ²³⁸U/²²⁶Ra ratios in the soil were 0.7 to 3.4 (arithmetic mean 1.7). The radiometric data were evaluated to explain ²³⁸U and ²²⁶Ra migration in the soil and the possible consequences to the environment.     

Determination of long-lived radionuclides in radioactive wastes from the IEA-R1 nuclear research reactor

Ion-exchange resins and activated charcoal beds are employed for purification of the cooling water that is pumped through the core of pool type nuclear research reactors. Once expended, these media are replaced and become radioactive wastes that contain low concentrations of long-lived fission and activation products, uranium isotopes and transuranium elements. Determination of the radioactive inventory is of paramount importance in the management of such radioactive wastes, which, besides high-energy photon emitters that can be identified and quantified directly by gamma-ray spectrometry, also contain pure alpha, pure beta and low-energy photon emitters whose quantitative determination require radiochemical separation. These later are collectively known as difficult to measure (DTM) radionuclides. A characterization program embracing the DTM radionuclides is currently in progress for spent ion-exchange resins and activated charcoal beds that were definitively withdrawn from the water cleanup system of the IEA-R1 nuclear research reactor. Radiochemical methods used in the characterization program include separations with specific anionic resins, chromatographic extractions and co-precipitation, which enabled the measurement of the activity concentrations of ⁹⁰Sr, ²³⁴U, ²³⁵U, ²³⁸U, ²³⁸Pu, ^239+240Pu, ²⁴¹Pu, ²⁴¹Am and ²⁴⁴Cm. An enhanced retention of uranium and transuranium elements was observed in the activated charcoal compared to the ion-exchange resins as a result of the tendency of actinides to undergo hydrolysis in aqueous solutions.     

Determination of plutonium-239,240 in environmental samples from surroundings of the Atomic Power Station Jaslovské Bohunice

Specific activity of^239,240Pu in contaminated soils from the bank of Manivier channel was determined to be in the range of 5–40 Bq·kg^?1 and for soils from the bank of Dudvah river 0.6–8 Bq·kg^?1. The ratio of^239,240Pu/¹³⁷Cs found in the samples is about 1·10^?4, which is very close to the ratio found in the pulp of high activity concentrate in the collecting tank of nuclear power plants (NPP).     

Evaluation of synthesis conditions for plastic scintillation foils used to measure alpha- and beta-emitting radionuclides

Plastic scintillation foils of polystyrene and polycarbonate with a thickness between 45 and 200 μm, have been produced using the solvent evaporation method. PSfoils presented a reproducible thickness (10–20%). PSfoils were characterized by the measurement of ³⁶Cl or ²⁴¹Am. For ³⁶Cl spectrum is located at medium energies since not all energy is deposited in the scintillator and not all betas interact with the foils. For ²⁴¹Am the efficiency values are very high and spectrum is a sharp peak located at high energies. ²²²Rn absorption (L_D and K) and desorption capacities of the PSfoils have been also evaluated.

     

Determination of naturally occurring radionuclides in ultrapure organic liquids

For the determination of trace elements in organic liquids radiochemical neutron activation analysis has been combined with counting methods geared to various decay modes of indicator radionuclides leading to a high sensitivity required for ultrapure samples. The activation parameters such as irradiation time, sample mass and neutron flux have been enlarged to the maximum possible in the available irradiation facility. Separation yields and adsorption losses have been studied in detail for a set of elements in order to rule out losses during the separation process. The attainable limits of detection are 2 · 10^–16g/g for U and Lu, in the 5 · 10^–15g/g range for Th and Sm, in the 1 · 10^–14g/g region for La, 5 · 10^–13g/g for Rb, Cd and 2 · 10^–12g/g for K and In. Although the analysis focused on traces of naturally occurring radioisotopes, results for Cr, Fe, W and Zn are presented as well.     

Determination of naturally occurring radionuclides in ultrapure organic liquids

For the determination of trace elements in organic liquids radiochemical neutron activation analysis has been combined with counting methods geared to various decay modes of indicator radionuclides leading to a high sensitivity required for ultrapure samples. The activation parameters such as irradiation time, sample mass and neutron flux have been enlarged to the maximum possible in the available irradiation facility. Separation yields and adsorption losses have been studied in detail for a set of elements in order to rule out losses during the separation process. The attainable limits of detection are 2 · 10^–16g/g for U and Lu, in the 5 · 10^–15g/g range for Th and Sm, in the 1 · 10^–14g/g region for La, 5 · 10^–13g/g for Rb, Cd and 2 · 10^–12g/g for K and In. Although the analysis focused on traces of naturally occurring radioisotopes, results for Cr, Fe, W and Zn are presented as well. Received: 14 May 1997 / Revised: 28 August 1997 / Accepted: 9 September 1997     

Determination of short-lived radionuclides in neutron-activated human head-hair samples

The Al, Na, Mn, Cl and Mg contents of human head-hair samples were determined by irradiating the samples in a thermal reactor and measuring their γ-activity by scintillation techniques. The concentration variations of these elements in hair samples originating from the same and different persons were studied.     

Determination of actinide nuclides in water samples from the primary circuit of a research reactor

Primary coolant samples from a research have been analyzed for^239,240Pu,²³⁸Pu,²³⁸U,²³⁷Np and²³⁹Np. The determination of²³⁷Np and²³⁸U was carried out with the help of isotope dilution neutron activation analysis with²³⁹Np or²³⁸Np as tracer. For determination of^239,240Pu and²³⁸Pu alpha spectroscopic isotope dilution analysis with²³⁸Pu as tracer was used.²³⁹Np was determined with the help of isotope dilution analysis using²³⁸Np as tracer. Nuclides were isolated by chemical separation on anionite resin. Before measurement, Pu isotopes were electrolytically deposited on stainless steel plates. Activity ratios referred to²³⁸U were reported. They are helpful for identification of the sources of actinide activity in reactor effluents.     

Determination of gamma-emitting radionuclides in the Sava river deposits

The concentrations of radionuclides in deposits from the Sava River were determined by gamma-ray spectrometry. Thirteen nuclear reactor radionuclides and eight naturally occurring radionuclides were determined. The site specific activity levels of the Sava River deposits were assessed. The results of measurements show that the radioactivity of the Sava River deposits is due to naturally occurring radionuclides and an elevated concentration of artificial radionuclides such as radiocesium and radioruthenium.     

Transfer of radionuclides to fruit

A study has been carried out to determine soil-plant transfer factors relevant to fruit crops. The current default values for¹³⁷Cs, Pu and Am used in the NRPB food-chain model FARMLAND were generally higher than the TFs observed. Lower values would be more appropriate for general assessments. For the United Kingdom, the current approach in which TF values for apples are applied to all domestically produced fruit is considered reasonable. This study also indicates that the assumption that TFs for fruit are the same as those for green vegetables is reasonable for¹³⁷Cs, Pu and Am, but, for⁹⁰Sr, data specific to apples would be preferable.