Radionuclide sources

During the last years ionizing radiation radionuclide sources were repeatedly withdrawn from illegal circulation in Dnepropetrovsk,... 

In 2000 the law-enforcement organs arrested an inhabitant of small towns Carichanka when he was trying to sell a defensive block with a radionuclide source. After that, his house was inspected thoroughly and three similar blocks were discovered hidden at different places. 

Khodakovsky, I. K. 1994. Radionuclide sources of arctic contamination. Arctic Research United States, 8, 262—265. 

As a simple example of how one would use Tables 1—5 for design of a 7-ray transmission gauge, let us select the best available radionuclide source to measure density changes in a cylinder of Comp B, 6cm in thickness. From eq (2), the 7-ray absorption coefficient for maximum sensitivity is 1/px or 1/1.67(6) - 0.0998. 

Table 7-14. Ranges of soil-to-plant transfer factors for selected radionuclides (source IUR, 1989).

Among common radionuclide sources are the natural environment, fallout from nuclear weapon tests, effluents from nuclear research laboratories, the nuclear power fuel cycle, radiopharmaceutical development, manufacturing, and various application, teaching and research uses. Decontamination and decommissioning activities at former nuclear facilities and the potential of terrorist radionuclide uses are current topics of interest for radioanalytical chemistry laboratories. Simplified information on the numerous radionuclides is conveniently found in Charts of the Nuclides such as Nuclides and Isotopes (revised by J. R. Parrington, H. D. Knox, S. L. Breneman, E. M. Baum, and F. Feiner, 15th Edition, 1996, distributed by GE Nuclear Energy). 

The detection systems first must be calibrated for counting efficiency to permit conversion of the sample count rate to the disintegration rate. These systems are monitored periodically for their stability and performance by measuring the count rates of reliable radionuclide sources and the radiation background. Records are maintained for each instrument to comply with quality assurance specifications. Graphs of count rates recorded at frequent intervals for periods of months or years provide a visual record of detector and background stability and indicate deviations from the norm. 

The detection limits obtained by excitation with radionuclides are of the order of several pg/g. Appreciably higher intensities and lower detection limits are, in general, achieved by X-ray tubes. Monoenergetic radiation may also be obtained with X-ray tubes in combination with a secondary target, and the intensity of the secondary radiation is of the same order as that obtained with radionuclide sources. 

Radionuclide / Source p/y Probe Alpha Probe X-ray Probe Pancake Probe Pj PM Wipe Test... 

Hoffmann, P., 1986. Application of radionuclide sources for excitation in energy-dispersive X-ray lluorescence... 

Specitications in purchasing detectors and tests of the received instrument systems can limit the contamination in detector materials and associated nearby components such as the sample holder, preamplifier, and radiation shield to acceptable levels. The background due to cross-contamination from other samples and placing highly radioactive sources near the detector can be prevented by careful laboratory practices. For example, solid and liquid radionuclide sources should be enclosed as thoroughly as is feasible when brought to the counting room. 

The QA officer and staff procure, store, and dispense QC samples, report QC results, and evaluate the implication of these results for the analytical program. The QA officer and staff prepare radionuclide sources for counting and solutions for spiking, i.e., tracing the radionuclide of interest. 

AR193 Radionuclide source terms from severe accidents to nuclear power plants with light water reactors, No. 2, 18 March 1987. 

FAW, R.E., Absorbed doses to skin from radionuclide sources on the body surface. Health Phys. 63 (1992) 443 48. 

The first photonuclear activation for analytical purposes was performed with radionuclides as the activating radiation source. These applications were reported in the early 1950s, although apparently the first beryllium determinations by photodisintegration were performed in the late 1930s in the Soviet Union. The analytical detection power of photon activation analysis using radionuclide sources is poor and restricted to the analysis of deuterium, beryllium, several fissile nuclides, and a few nuclides that have low-lying isomeric states. Nonetheless, nuclide excitation is still in use. 

In isotope power sources (actually radionuclide sources), energy of radioactive decay of nuclei is used. The radionuclides themselves are products of fission or activation due to irradiation by neutrons. 

Recent probabilistic risk assessments [In-5-9] establish that there is room for accident management to influence the consequences of reactor accidents. These risk assessments show there to be orders of magnitude uncertainty in the radionuclide releases as a result of accidents at nuclear power plants. A very significant portion of this uncertainty comes from uncertainty in the details of radionuclide behavior that can be influenced by accident management measures. The accident management measures taken to affect the radionuclide source term are not necessarily distinct from those taken to arrest or... 

This report examines the severe accident sequences and radionuclide source terms at the Sizewell pressurised water reactor with a prestressed concrete containment, the Konvoi pressurized water reactor with a steel primary containment, the European Pressurised water Reactor (EPR) and a boiling water reactor with a Mark 2 containment. 

This dociunent describes a representative radionuclide source term to the containments of reactors for use in the traditional design basis accident analysis. The source term is based on the more mechanistic studies of radionuclide behaviour conducted since the accident at Three Mile Island. Although the source is representative of the magnitude and timing of severe accident source terms, it is not intended to represent any specific severe accident sequence nor is it intended to be a boimding source term. 

This report examines the severe accident sequences and radionuclide source terms at the Sizewell pressurised water reactor with a piestressed concrete containment, the Konvoi pressurized water reactor with a steel primary contaimnent, the European Pressurised water Reactor (EPR) and a boiling water reactor with a Mark 2 containment. The report concludes that the key accident sequences for European plant designs are transient events and small loss-of-coolant accidents, loss of cooling during shutdown, and containment bypass sequences. The most important chemical and transport phenomena are found to be revaporisation of volatile radionuclides from the reactor coolant system, iodine chemistry, and release paths through the plant. Additional research is recommended on release of fission products from the fuel, release of fission products from the reactor coolant system, ehemistry of iodine, and transport of radionuclide through plants. 

Since both reactions are induced by fast neutrons having energies >10MeV, the total amount of Co released from the materials to the primary coolant of a 1300MWe PWR was calculated to be only on the order of 10" Bq per year (Sie-mens/KWU, unpublished). In this calculation, the essential radionuclide sources were assumed to be corrosion product deposits on the fuel rods as well as corrosion and/or wear from in-core materials. This low production rate raises the question of whether the y rays at 122 and 136 keV occasionally detected in waste water really belong to Co or whether they are caused by side-peaks originating from the decay of other radionuclides present in the samples. 

The current technical basis for predicting the near field performance for HLW repositories has bera reviewed and discussed in May 1993 in Cadarache, (F) at an international workshop [11]. As an outcome of this workshop, it seems that still various critical issues need further investigations such as the near field geochemical environment for various host rock formations, release of radionuclides from waste forms, transport and retardation mechanism of released radionuclides, source-term modelling and integration of the near field performance assessment with the far field. 

Commonly used commercial sources are the QCY and QCYK Mixed Nuclide sources provided in the UK by AEA Technology QSA and, in the USA, the calibrated mixture of Sb, Eu and Eu available from the National Institute of Standards and Technology (NIST). In Germany the PTB (PhysikaUsch-Techniche Bundesanstalt) supply another suitable mixed radionuclide source. (The QCYK source, and its spectrum is examined in Chapter 8, Section 8.5.1.)... 

Analyses are performed with the MAAP4 code to study the progression of severe accident sequences and to define the radionuclide source terms. The severe accident analysis is discussed in subsection 5.5. 

INSAG-2 Radionuclide source terms from severe accidents to 1987... 

A short overview of radionuclide sources, decay paths, ingestion pathways and behaviors in soils and plants follows Brady et al. (1999) and others as cited. 

---