scholarly journals An improved method of lifetime measurement of nuclei in radioactive decay chain

2017 ◽  
Vol 850 ◽  
pp. 68-71 ◽  
Author(s):  
J.M. Puzović ◽  
D. Manić ◽  
L.J. Nađđerđ
Keyword(s):  
Radioactive Decay ◽  
Decay Chain ◽  
Lifetime Measurement ◽  
Improved Method

scholarly journals Radon content in Danish till deposits: relationship with redox conditions and age

1969 ◽  
Vol 20 ◽  
pp. 39-42
Author(s):  
Peter Gravesen ◽  
Peter Roll Jakobsen
Keyword(s):  
Water Content ◽  
Clay Minerals ◽  
Organic Material ◽  
Half Life ◽  
Radioactive Decay ◽  
Decay Chain ◽  
Redox Conditions ◽  
Transport Rate ◽  
Radon Content

Radon (222Rn) is a radioactive, noble insoluble gas with a half-life of 3.8 days. It belongs to the uranium (238U) decay chain where radon is formed from radium (226Ra). Uranium and radium are built into mineral structures or are, for example, adsorbed on the surface of clay minerals, limonite or organic material. When radon is formed by radioactive decay from radium, parts of it enter the pores of rocks and soils and are transported by diffusive or advective forces in the pores. The transport rate depends on the permeability and water content in the pores (Nazaroff 1992).

scholarly journals DEVELOPMENT OF DECAY HEAT MODEL FOR RAST-K

2021 ◽  
Vol 247 ◽  
pp. 07009
Author(s):  
Siarhei Dzianisau ◽  
Jinsu Park ◽  
Sooyoung Choi ◽  
Alexey Cherezov ◽  
Xianan Du ◽  
...  
Keyword(s):  
Radioactive Decay ◽  
Fission Products ◽  
Reactor Power ◽  
Total Power ◽  
Improved Method ◽  
Reactor Operation ◽  
Decay Heat ◽  
Individual Contributions ◽  
Computation Speed

Decay heat (DH) is the heat produced through a radioactive decay of fission products during or after a reactor operation. It is known as the second largest source of power in the core after fission. Being such a strong contributor to reactor power, it should be accurately determined at any time of reactor operation. Currently, there are two main approaches for DH estimation used in reactor simulation codes. One approach is based on careful inventorying of all produced target nuclides and their individual contributions to total power. Alternatively, the other popular approach is based on collapsing all target fission products into a small number of groups similar to delayed neutron estimation techniques. However, the last (multigroup) method currently has limitations when used in some transient scenarios such as transients occurred in fresh fuel. In this study, the multigroup method was further developed for reducing limitations while retaining the advantage in computation speed. Then, it was implemented into Reactor Analysis code for Steady state and Transient (RAST-K) and tested against other codes. As a result, the improved method was found capable of determining DH power at all tested stages of reactor operation under any tested operation scenario. In particular, the test simulations using the improved method showed better results in those scenarios that were under accuracy limitations of the original multigroup method. Overall, the quality of transient calculations in RAST-K was improved when using the newly implemented DH module.

Direct alpha-recoil as a process to generate U-234/U-238 disequilibrium in groundwater

2006 ◽  
Vol 932 ◽  
Author(s):  
Kari Rasilainen ◽  
Henrik Nordman ◽  
Juhani Suksi ◽  
Nuria Marcos
Keyword(s):  
Input Data ◽  
Activity Ratio ◽  
Radioactive Decay ◽  
Decay Chain ◽  
The Novel ◽  
Slow Process ◽  
Site Specific ◽  
Coupled Equations ◽  
Radioactive Disequilibrium ◽  
Modelling Approach

ABSTRACTWe discuss quantitatively the capability of direct α-recoil to create observable radioactive disequilibrium (U-234/U-238 activity ratio > 1) in flowing groundwater. Coupled equations for radioactive decay chain are formulated for the solid U source and for the corresponding groundwater receiving the recoiling U-234 atoms. U-rich fracture coating material and the water flowing in the fracture are discussed in detail.The novel modelling approach worked well and provides a useful tool for more detailed site-specific studies with more detailed input data. The approach appears feasible because the equations are based on straightforward mass balance considerations.α-recoil -induced enrichment of U-234 in groundwater is a slow process: the increase of U-234/U-238 activity ratio to notable values above unity will take hundreds to thousands of years. Strong groundwater flow prevents any local recoil-induced U-234 enrichment in the water.

Comparison of 222Rn measurement methods in caves

2021 ◽  
Author(s):  
Sara Gil-Oncina ◽  
Concepción Pla ◽  
Javier Valdes-Abellan ◽  
Noé Garcia-Martinez ◽  
David Benavente
Keyword(s):  
Activity Concentration ◽  
Radioactive Decay ◽  
Environmental Parameters ◽  
Decay Chain ◽  
Air Samples ◽  
Radon Activity ◽  
222Rn Concentration ◽  
Different Types ◽  
The One ◽  
Ionizing Radiation Exposure

<p>Radon (222Rn) is a naturally inert radioactive gas, originating from the radioactive decay of 226Ra in the 238U radioactive decay chain. 222Rn has a variety of geoscientific applications. 222Rn, however, represents the most significant source of ionizing radiation exposure and can be critical in underground working and living spaces with little or no ventilation. Particularly, caves are recognized as special indoor occupational environments where extremely elevated concentrations of 222Rn may occur during, at least, half-year during its recharged stage.</p><p>The measurement of radon activity concentration in air can be performed using different types of equipment and methodologies. However, it is characterized by the dispersion for relatively short exposition times and depends on the radon activity concentration and environmental parameters. This investigation aims to compare different types of equipment and methodologies to measure 222Rn under real cave conditions.</p><p>Rull Cave is located in Vall d’Ebo, in the south-east of Spain (Alicante province). The host rock of the cave is composed of Miocene conglomerates lying on Cretaceous limestones. Above the cave, the soil has a discontinuous thickness of approximately 1 m. The investigation is performed in winter where the cave remains discharged. During this period, the gas concentration reaches minimum values and presents low fluctuation of radon activity concentration. Temperatures in Rull Cave range between 17 and 20°C, the mean relative humidity reaches about 87%, and the constant pressure of 975 mBar. 222Rn measurements have been taken continually since 2016, ranging from 645 to 3959 Bq/m3.</p><p>We compare, firstly, cave air radon with three devices: AlphaGUARD DF2000, Radim 5WP, and RadonScout Plus. The second method involves the measurement of air radon samples after collecting them in sampling bags. We perform two types of measures: (i) in-situ measures of air samples and (ii) measure of the collected sampling bags 24-hours later (in the laboratory). For this purpose, we use opaque and transparent 1L-gas sampling bags (GSB), and we also evaluate the influence of the air volume (2 or 4 L) on radon activity concentration measurement using AlphaGUARD DF2000 at 0.3 L/min pump flow.</p><p>These findings reveal that i) all devices have similar values of radon activity concentration, with a difference between AlphaGUARD DF2000 with Radim 5WP, and RadonScout Plus of -32% and +19 %, respectively; ii) the use of transparent or opaque GSB provide similar 222Rn concentration; iii) 222Rn concentration after 24-hours is nearly the same than samples tested immediately after collecting; and iv) direct data and the one collected in GSB are equivalent, although 4L GSB often register higher values than 2L. Both methodologies highlight the known problem of radon fluctuations at a short scale. We do recommend collecting air samples in 4L-GSB. It presents practical advantages for cave studies. Thus, 222Rn can be measured in cave areas that are nor not easily accessible areas. In addition, this methodology allows increasing the number of measurements, as well as to safety keep the devices at the lab.</p>

Radioactive Decay Chain Truncation Rules for Emergency Response Radiological Assessments.

2017 ◽  
Author(s):  
Lainy Dromgoole Cochran ◽  
Terrence D. Kraus ◽  
Brian D. Hunt ◽  
Lainy Dromgoole Cochran
Keyword(s):  
Emergency Response ◽  
Radioactive Decay ◽  
Decay Chain

15.—Natural Radioactive Decay Series Elements in the Oceans and Sediments

1972 ◽  
Vol 72 (1) ◽  
pp. 167-182 ◽  
Author(s):  
J Thomson ◽  
A. Walton
Keyword(s):  
Radioactive Decay ◽  
Decay Chain ◽  
Secular Equilibrium ◽  
Marine Geochemistry ◽  
Daughter Nuclide ◽  
Decay Products ◽  
Naturally Occurring ◽  
Decay Series ◽  
Time Required ◽  
Radio Isotopes

The parents of the three naturally occurring radioactive decay series (text-fig. 1),232Th, 238U and 235U, have existed since the time of formation of the earth and through the process of radioactive decay have continuously generated their shorterlived daughter radio-isotopes. Under conditions where these decay products are not separated from the parents the situation referred to as secular equilibrium may be attained at which the activity ratio of any two daughters in the same decay chain is unity. The time required for the attainment of this situation corresponds to several half-lives of the longest lived daughter nuclide. In a great many instances, however, secular equilibrium is not achieved. Excellent examples of disequilibrium are to be found in the distribution of natural radioactive decay series elements in the oceans and sediments. These situations can be used to advantage in marine geochemistry to obtain information on residence times of elements in the oceans and rates of sedimentation occurring under a variety of conditions.

The radioactive decay series 138Nd → 138Pr → 138Ce

1970 ◽  
Vol 48 (14) ◽  
pp. 2151-2157 ◽  
Author(s):  
James J. Hogan
Keyword(s):  
Direct Measurement ◽  
Gamma Rays ◽  
Radioactive Decay ◽  
Excited Level ◽  
Branching Ratio ◽  
Decay Chain ◽  
Decay Series

Measurements of the energies and intensities of gamma rays associated with decay of 138Nd, 138Prm, and 138Prg have been performed using a Ge(Li) detector. The branching ratio to a previously unreported excited level of 138Pr (328.1 keV) has been measured, thus allowing for direct measurement of the decay of 138Nd. Half-lives of 2.20 ± 0.07 and 5.04 ± 0.09 h have been measured for 138Prm and 138Nd, respectively. Decay schemes for 138Prm → 138Ce and for the decay chain 138Nd → 138Prg → 138Ce are proposed.

scholarly journals DECSERVIS: a tool for radioactive decay series visualisation

2006 ◽  
Vol 4 (4) ◽  
pp. 822-834 ◽  
Author(s):  
Saad Azzam ◽  
Juhani Suksi
Keyword(s):  
Initial Conditions ◽  
Radioactive Decay ◽  
Decay Chain ◽  
Decay Series ◽  
Closed Systems ◽  
Natural Decay ◽  
User Friendly ◽  
Interactive Visualisation ◽  
Flexible Operation ◽  
Chain Decay

AbstractWe have developed an interactive visualisation tool, decay series visualisation (DECSERVIS), for exploring the three natural radioactive decay chains. Through DECSERVIS, one can investigate the full decay scheme of any natural decay chain radionuclide to obtain the number of nuclides, their masses, activities, and activity ratios, accounting for all the daughters, starting from initial conditions freely chosen by the user. The tool has been developed particularly for user friendly and flexible operation. Chain decay in closed systems can be explored as a function of time with various graphical presentations such as solid curve and column diagrams or animation. We present several exploration examples related to geological dating. DECSERVIS will be freely available on request.

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