Characterization of the Radiochemical Activity in CANDU Steam Generators

2009 ◽  
Author(s):  
Aamir Husain ◽  
Yury Verzilov ◽  
Sriram Suryanarayan ◽  
Armando B. Antoniazzi
Keyword(s):  
Dose Rate ◽  
Beta Activity ◽  
Steam Generators ◽  
Activity Data ◽  
Dose Rates ◽  
Detailed Assessment ◽  
Interim Storage ◽  
Secondary Side

The scope of mid-life refurbishment activities at some CANDU plants includes replacement of the existing steam generators. Shipment of the discarded steam generators for interim storage, intact disposal or for recycling via metal melting requires an assessment of dose rates and the inventory of radionuclides within the components. Kinectrics was contracted by CANDU utility owners to develop such data. This paper presents the detailed methodology employed to develop dose rate and radionuclide inventory data for radionuclides within both in-service and the out-of-service (in-storage) steam generators. The data were developed as follows: a) archived tube sections from various steam generators were characterized; scaling factors were derived using the detailed alpha and beta activity data obtained, b) in-situ gamma spectrometry (using germanium and cadmium zinc telluride detectors) and dose rate surveys were performed at various steam generators and c) a detailed assessment of the tritium inventory in various primary and secondary side components was performed.

Natural radioactivity measurements and external dose estimation by car-borne survey in Douala city, Cameroon

2018 ◽  
Vol 53 (4) ◽  
pp. 255-263 ◽  
Author(s):  
S.D. Takoukam Soh ◽  
Saïdou ◽  
M. Hosoda ◽  
J.E. Ndjana Nkoulou II ◽  
N. Akata ◽  
...  
Keyword(s):  
Dose Rate ◽  
Absorbed Dose ◽  
Distribution Map ◽  
Heterogeneous Distribution ◽  
World Average ◽  
Dose Rates ◽  
Average Value ◽  
Activity Concentrations ◽  
The World

A car-borne survey was carried out in Douala, the largest city in Cameroon to make a detailed distribution map of the absorbed dose rate in the city, to locate the high natural radiation areas useful later to carry out indoor radon, thoron, and thoron progeny measurements. Gamma-ray dose rates were measured using 3-in × 3-in NaI(Tl) detector. Activity concentrations of238U,232Th and40K in soil from Douala city were determined by two methods: the first, usingin situgamma spectrometry and the second, at the laboratory using a NaI(Tl) detector. A heterogeneous distribution of absorbed dose rates in air was observed on the dose rate distribution map, and varies from 29 to 86 nGy h−1with an average of 50 nGy h−1, lower than the world average value of 59 nGy h−1. The activity concentrations with NaI(Tl) detector varied from 18 to 47 Bq kg−1for238U, 21 to 54 Bq kg−1for232Th, and 10 to 410 Bq kg−1for40K with averages of 29, 38, and 202 Bq kg−1respectively, forin situmeasurements. They vary between 29–98 Bq kg−1for238U, 29–92 Bq kg−1for232Th, and 40 to 79 Bq kg−1for40K, with averages of 60, 57, and 56 Bq kg−1respectively for soil samples collected at Douala III subdivision. The highest value of the annual effective dose forin situmeasurements by car was observed at Ndogbong and was found to be 0.7 mSv y−1, higher than the world average value of 0.5 mSv y−1.

EFFECTS OF LOCAL BUILDING MATERIALS ON INDOOR GAMMA DOSES AND RELATED RADIOLOGICAL HEALTH RISKS, AYVACIK, ÇANAKKALE/TURKEY

2020 ◽  
Vol 190 (1) ◽  
pp. 108-117
Author(s):  
Gülcan Top ◽  
Yüksel Örgün ◽  
Gürsel Karahan ◽  
Mark Horvath ◽  
Györgyi Kampfl
Keyword(s):  
Dose Rate ◽  
Building Materials ◽  
Gamma Dose ◽  
Cancer Risks ◽  
Dose Rates ◽  
Gamma Dose Rates ◽  
Gamma Analysis ◽  
Local Soil ◽  
Radiological Health

Abstract In situ indoor gamma dose rate measurements were held in 79 dwellings by NaI(Tl) scintillation probe connected portable dose rate meter. For the building materials and impurities (nodules), spectrometric gamma analysis was applied by a high-resolution HpGe detector. For Ahmetçe and Nusratlı villages in Ayvacik/Çanakkale (Turkey), the measured in situ indoor gamma dose rates and related indoor annual effective dose equivalents (AEDEin) were 3 and 3.3 times, and indoor excess lifetime cancer risks (ELCRin) were 4.25 and 4.68 times higher than those of the world averages, respectively. The used local rocks were mostly ignimbrite and dacitic–rhyolitic tuffaceous (Arıklı tuff), and wall plasters were made of local soil. The highest in situ indoor gamma dose rates of the region belonged to Nusratlı village due to the intense impurities (nodules) and hydrothermal alterations in Arıklı tuff. Spectrometric gamma results revealed that 40K has an important effect on the indoor gamma doses.

Dose Rate Effects on the Accumulation of Radiation Damage

2007 ◽  
Author(s):  
V. V. Rondinella ◽  
T. Wiss ◽  
J.-P. Hiernaut ◽  
D. Staicu
Keyword(s):  
Dose Rate ◽  
Radiation Damage ◽  
Alpha Decay ◽  
Lattice Parameter ◽  
Time Interval ◽  
Spent Fuel ◽  
Dose Rates ◽  
Dose Rate Effects ◽  
Doped Materials ◽  
Interim Storage

During storage, spent fuel and other waste forms accumulate alpha-decay damage (and He). The dose rates and the temperatures experienced during storage are lower than during in-pile operation: however, the duration of the storage is much longer (of the order of up to a few hundred years if extended interim storage concepts are considered); if final disposal in the repository is considered, the time interval in which radiation damage accumulates is open-ended. In order to simulate within timeframes suitable for laboratory experiments long-term accumulation of alpha-decay damage, the so-called alpha-doped materials can be used, i.e. materials loaded with short-lived alpha-emitters (like e.g. Pu-238, U-233, etc.). The question is often posed if the accelerated accumulation of decay damage and He obtained using alpha-doped materials does cause some artefact related to the rate of accumulation rather than by the integrated dose. This work presents evidence that, at least within the range of alpha-activities considered, there is no dose rate effect. By comparing property evolution as a function of accumulated dpa for alpha-doped materials with activities of ∼1010 and ∼108 Bq/g, respectively, the same trends and levels of alteration are observed. In particular, macroscopic properties like hardness (measured by Vickers indentation) or swelling (evolution of lattice parameter derived from XRD), and microstructural formation and accumulation of defects in the lattice of the alpha-doped material are investigated, showing a remarkable similarity of behaviour vs. dpa independently not only from the dose rate, but also from the composition (namely, Pu and U are considered).

Dose Validation in the Dutch Interim Waste Storage Facility

2009 ◽  
Author(s):  
Jeroen Welbergen ◽  
Leo van Velzen
Keyword(s):  
Radioactive Waste ◽  
Neutron Flux ◽  
Thermal Neutron ◽  
Dose Rate ◽  
Thermal Neutron Flux ◽  
The Public ◽  
Dose Rates ◽  
Waste Storage ◽  
Flux Measurements ◽  
Interim Storage

All radioactive waste in the Netherlands is collected by COVRA (acronym for Central Organisation for Radioactive Waste) that operates a facility for treatment of waste including interim storage buildings for HLW, LILW and TENORM (Calcinate and U3O8). Like many other waste management organisations, COVRA developed and adopted different waste storage strategies for different types of waste. The basis of all strategies is Isolation, Control and Surveillance (ICS), a principle aimed at minimization of dose to operators and the public alike. The stacking of waste in the storage buildings directly follows from this principle. To minimize radiation exposure of employees, waste is stacked in blocks. In these block the packages with low dose rates are placed on the outside and are shielding packages with higher dose rates and neutron sources inside. The packages with the lowest dose rate are stacked against the outer walls to minimize radiation into the environment. In 2004, a novel Non-Destructive Assay (NDA) method was used to validate the applied waste storage strategies in terms of spatial dose rate distribution. With this method measurements were performed in one of the interim storage modules for LILW. The dose rate at a height of 6m, mainly responsible for the sky-shine at the site boundary, was somewhat higher then expected. Based on the experience and feedback, the NDA method was developed further, into the present INDSS-R (acronym for INDoor Survey System – Radiation) method. This new method was put to the test in 2006 with a second series of spatial radiological measurements. The main aim was now to verify the reproducibility of the method. In 2008, a third series of measurements was carried out and the following data was collected: • dose rate (using a pressurized ionisation chamber) • nuclide depended gamma photon flux (by means of a 3*3″ NaI detector ) • thermal neutron flux measurements (by means of LiI(Eu) detector) The results of the third serial of spatial radiological and thermal neutron flux measurements will be presented and compared to the 2004 and 2006 data on the operational dose for operators and for the public.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

A very rapid in situ Kikuchi technique to determine relative crystal misorientation

1988 ◽  
Vol 46 ◽  
pp. 830-831
Author(s):  
J. I. Bennetch
Keyword(s):  
Electron Beam ◽  
Analytical Techniques ◽  
Superplastic Forming ◽  
The Other ◽  
Kikuchi Pattern ◽  
Kikuchi Line ◽  
Line Analysis

In a recent study of the superplastic forming (SPF) behavior of certain Al-Li-X alloys, the relative misorientation between adjacent (sub)grains proved to be an important parameter. It is well established that the most accurate way to determine misorientation across boundaries is by Kikuchi line analysis. However, the SPF study required the characterization of a large number of (sub)grains in each sample to be statistically meaningful, a very time-consuming task even for comparatively rapid Kikuchi analytical techniques.In order to circumvent this problem, an alternate, even more rapid in-situ Kikuchi technique was devised, eliminating the need for the developing of negatives and any subsequent measurements on photographic plates. All that is required is a double tilt low backlash goniometer capable of tilting ± 45° in one axis and ± 30° in the other axis. The procedure is as follows. While viewing the microscope screen, one merely tilts the specimen until a standard recognizable reference Kikuchi pattern is centered, making sure, at the same time, that the focused electron beam remains on the (sub)grain in question.

Coherent electron nanodiffraction from clean silver nano particles in a UHV STEM

1993 ◽  
Vol 51 ◽  
pp. 1058-1059
Author(s):  
J. Liu ◽  
M. Pan ◽  
G. E. Spinnler
Keyword(s):  
Supported Catalysts ◽  
Imaging Techniques ◽  
Nano Particles ◽  
Metal Particles ◽  
Shape Structure ◽  
Dynamical Simulations ◽  
Small Metal Particles ◽  
Extract Information

Small metal particles have peculiar chemical and physical properties as compared to bulk materials. They are especially important in catalysis since metal particles are common constituents of supported catalysts. The structural characterization of small particles is of primary importance for the understanding of structure-catalytic activity relationships. The shape and size of metal particles larger than approximately 5 nm in diameter can be determined by several imaging techniques. It is difficult, however, to deduce the shape of smaller metal particles. Coherent electron nanodiffraction (CEND) patterns from nano particles contain information about the particle size, shape, structure and defects etc. As part of an on-going program of STEM characterization of supported catalysts we report some preliminary results of CEND study of Ag nano particles, deposited in situ in a UHV STEM instrument, and compare the experimental results with full dynamical simulations in order to extract information about the shape of Ag nano particles.

Characterization of the glycoconjugates of boar testis and epididymis

Reproduction ◽  
2000 ◽  
pp. 325-335 ◽  
Author(s):  
A Calvo ◽  
LM Pastor ◽  
S Bonet ◽  
E Pinart ◽  
M Ventura
Keyword(s):  
Ricinus Communis ◽  
Lectin Histochemistry ◽  
Apical Part ◽  
Seminiferous Tubules ◽  
In Situ Characterization ◽  
Intense Staining ◽  
Terminal Galactose ◽  
Boar Spermatozoa

Lectin histochemistry was used to perform in situ characterization of the glycoconjugates present in boar testis and epididymis. Thirteen horseradish peroxidase- or digoxigenin-labelled lectins were used in samples obtained from healthy fertile boars. The acrosomes of the spermatids were stained intensely by lectins with affinity for galactose and N-acetyl-galactosamine residues, these being soybean, peanut and Ricinus communis agglutinins. Sertoli cells were stained selectively by Maackia ammurensis agglutinin. The lamina propria of seminiferous tubules showed the most intense staining with fucose-binding lectins. The Golgi area and the apical part of the principal cells of the epididymis were stained intensely with many lectins and their distribution was similar in the three zones of the epididymis. On the basis of lectin affinity, both testis and epididymis appear to have N- and O-linked glycoconjugates. Spermatozoa from different epididymal regions showed different expression of terminal galactose and N-acetyl-galactosamine. Sialic acid (specifically alpha2,3 neuraminic-5 acid) was probably incorporated into spermatozoa along the extratesticular ducts. These findings indicate that the development and maturation of boar spermatozoa are accompanied by changes in glycoconjugates. As some lectins stain cellular or extracellular compartments specifically, these lectins could be useful markers in histopathological evaluation of diseases of boar testis and epididymis.

Spectro-mechanical Characterization of Aromaticity and Maturity of Kerogens in Oil Shale at 6 nm Spatial Resolution

2018 ◽  
Author(s):  
Devon Jakob ◽  
Le Wang ◽  
Haomin Wang ◽  
Xiaoji Xu
Keyword(s):  
Spatial Resolution ◽  
Oil Shale ◽  
Infrared Imaging ◽  
Mechanical Characterization ◽  
Optical Diffraction ◽  
Chemical Compositions ◽  
Valuable Insight ◽  
Eagle Ford Shale

<p>In situ measurements of the chemical compositions and mechanical properties of kerogen help understand the formation, transformation, and utilization of organic matter in the oil shale at the nanoscale. However, the optical diffraction limit prevents attainment of nanoscale resolution using conventional spectroscopy and microscopy. Here, we utilize peak force infrared (PFIR) microscopy for multimodal characterization of kerogen in oil shale. The PFIR provides correlative infrared imaging, mechanical mapping, and broadband infrared spectroscopy capability with 6 nm spatial resolution. We observed nanoscale heterogeneity in the chemical composition, aromaticity, and maturity of the kerogens from oil shales from Eagle Ford shale play in Texas. The kerogen aromaticity positively correlates with the local mechanical moduli of the surrounding inorganic matrix, manifesting the Le Chatelier’s principle. In situ spectro-mechanical characterization of oil shale will yield valuable insight for geochemical and geomechanical modeling on the origin and transformation of kerogen in the oil shale.</p>

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