Question

You are given a soil sample taken from the environment. Give examples of any Uranium isotopes that may be present. What other long-lived isotopes may also be present in the sample? Briefly discuss what you understand by the term “decay chain”, giving some examples of the type of decay processes involved

Answer 1

Serbia was bombarded by NATO. One of the cities most affected by the consequences of bombardment with uranium is the city of Vranje, where the consequences are felt even today. Due to the influence of uranium, the mortality rate has increased. This paper presents the effects of some of the radionuclides that have contaminated the soil, as well as the connection between soil and plants that grow on that soil. The performed measurements of radionuclides (226Ra, 40K, 232Th, 238U, and 235U). The results show that the content of each of these radionuclides has different concentrations, but what is important is that some values are even below the detection limit

Uranium (92U) is a naturally occurring radioactive element that has no stable isotope. It has two primordial isotopes, uranium-238 and uranium-235, that have long half-lives and are found in appreciable quantity in the Earth's crust. The decay product uranium-234 is also found. Other isotopes such as uranium-233 have been produced in breeder reactors. In addition to isotopes found in nature or nuclear reactors, many isotopes with far shorter half-lives have been produced, ranging from 215U to 242U (with the exception of 220U and 241U). The standard atomic weight of natural uranium is 238.02891(3).

Naturally occurring uranium is composed of three major isotopes, uranium-238 (99.2739–99.2752% natural abundance), uranium-235 (0.7198–0.7202%), and uranium-234 (0.0050–0.0059%).[2] All three isotopes are radioactive, creating radioisotopes, with the most abundant and stable being uranium-238 with a half-life of 4.4683×109 years (close to the age of the Earth).

Uranium-238 is an alpha emitter, decaying through the 18-member uranium series into lead-206. The decay series of uranium-235 (historically called actino-uranium) has 15 members and ends in lead-207. The constant rates of decay in these series makes comparison of the ratios of parent-to-daughter elements useful in radiometric dating. Uranium-233 is made from thorium-232 by neutron bombardment.

In nuclear science, the decay chain refers to a series of radioactive decays of different radioactive decay products as a sequential series of transformations. It is also known as a "radioactive cascade". Most radioisotopes do not decay directly to a stable state, but rather undergo a series of decays until eventually a stable isotope is reached.

Decay stages are referred to by their relationship to previous or subsequent stages. A parent isotope is one that undergoes decay to form a daughter isotope. One example of this is uranium (atomic number 92) decaying into thorium (atomic number 90). The daughter isotope may be stable or it may decay to form a daughter isotope of its own. The daughter of a daughter isotope is sometimes called a granddaughter isotope.

Information scientists can use known decay chains to infer the age of undated nuclear materials, such as smuggled nuclear materials that are interdicted by authorities. We chose a handful of isotopes, based on their significance to nuclear forensics, and we display the decay chain of those isotopes below. The selected isotopes are isotopes of elements in the Actinide Series on the Periodic Table of Elements. The element numbers range from 90 to 96 - Thorium (no. 90), Proactinium (no. 91), Uranium (no. 92), Neptunium (no. 93), Plutonium (no. 94), Americium (no. 95), and Curium (no. 96).

This table summarizes the relationship between the selected isotopes, their elements, and the isotopes' decay chains.

Selected Isotope	Element	Element No.	Decay Chain Description
Th-232	Thorium	90	The Thorium Series
Pa-231	Proactinium	91	A child in the Actinium Series
U-235	Uranium	92	The Actinium Series
U-238	Uranium	92	The Radium, or Uranium, Series
Np-237	Neptunium	93	The Neptunium Series
Pu-239	Plutonium	94	A parent of the Actinium Series
Am-241	Americium	95	A parent of the Neptunium Series
Cm-241	Curium	96	A (distant) parent of the Actinium Series

Decay chain description source: Modified from Wikipedia's "decay chain" entry.

Decay Chain of Isotope Th-232

The 4n chain of Th-232 is commonly called the Thorium Series. Beginning with naturally occurring thorium-232, this series includes the following elements: actinium, bismuth, lead, polonium, radium and radon. All are present, at least transiently, in any natural thorium-containing sample, whether metal, compound, or mineral. The series terminates with lead-208.

The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wikipedia.

Image source: Thorium SVG image by Wikipedia contributor BatesIsBack.

Decay Chain of Isotope Pa-231

Pa-231 is a child in the Actinium Series. Beginning with the naturally-occurring isotope U-235, this decay series includes the following elements: Actinium, astatine, bismuth, francium, lead, polonium, protactinium, radium, radon, thallium, and thorium. All are present, at least transiently, in any sample containing uranium-235, whether metal, compound, ore, or mineral. This series terminates with the stable isotope lead-207.



The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wikipedia.

Image source: Modified by Chloe Reynolds based on the Thorium SVG image by Wikipedia contributor BatesIsBack.

Decay Chain of Isotope U-235

The 4n+3 chain of uranium-235 is commonly called the "actinium series". Beginning with the naturally-occurring isotope U-235, this decay series includes the following elements: Actinium, astatine, bismuth, francium, lead, polonium, protactinium, radium, radon, thallium, and thorium. All are present, at least transiently, in any sample containing uranium-235, whether metal, compound, ore, or mineral. This series terminates with the stable isotope lead-207.

The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wikipedia.

Image source: Modified by Chloe Reynolds based on the Thorium SVG image by Wikipedia contributor BatesIsBack.

Decay Chain of Isotope U-238

The 4n+2 chain of U-238 is commonly called the Radium Series (sometimes Uranium Series). Beginning with naturally occurring uranium-238, this series includes the following elements: astatine, bismuth, lead, polonium, protactinium, radium, radon, thallium and thorium. All are present, at least transiently, in any natural uranium-containing sample, whether metal, compound, or mineral. The series terminates with lead-206.

The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wikipedia contributor Tosaka.

Modified by Chloe Reynolds based on the Thorium SVG image by Wikipedia contributor BatesIsBack and the Radium Series png image by Wikipedia contributor Tosaka.

Decay Chain of Isotope Np-237

The 4n + 1 chain of Np-237 is commonly called the Neptunium Series. In this series, only two of the elements are found naturally, bismuth and thallium. A smoke detector containing an americium-241 ionization chamber accumulates a significant amount of neptunium-237 as its americium decays; the following elements are also present in it, at least transiently, as decay products of the neptunium: actinium, astatine, bismuth, francium, lead, polonium, protactinium, radium, thallium, thorium and uranium. Since this series was only studied more recently, its nuclides do not have historic names.

The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wikipedia.

Modified by Chloe Reynolds based on the Neptunium SVG image by Wikipedia contributor BatesIsBack.

Decay Chain of Isotope Pu-239

Pu-239 decays into U-235, which is the start of the Actinium Series. Beginning with the isotope U-235, this decay series includes the following elements: Actinium, astatine, bismuth, francium, lead, polonium, protactinium, radium, radon, thallium, and thorium. All are present, at least transiently, in any sample containing uranium-235, whether metal, compound, ore, or mineral. This series terminates with the stable isotope lead-207.

The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wikipedia.

Image source: Modified by Chloe Reynolds based on the Thorium SVG image by Wikipedia contributor BatesIsBack.

Decay Chain of Isotope Am-241

Am-241 decays into Np-237 and then follows the Neptunium Series decay chain. The following elements are also present, at least transiently, as decay products of the neptunium: actinium, astatine, bismuth, francium, lead, polonium, protactinium, radium, thallium, thorium, and uranium.

The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wikipedia.

Modified by Chloe Reynolds based on the Neptunium SVG image by Wikipedia contributor BatesIsBack.