Summary of Nuclear Reaction: Activity

Goals

1. Grasp the concept of activity of a radioactive sample.

2. Calculate the activity of various radioactive species.

3. Recognize the significance of nuclear reactions in industrial and healthcare settings.

Contextualization

Nuclear reactions are fundamental in numerous scientific and technological domains. From generating energy in nuclear power stations to medical applications like treatments and diagnostics, a solid understanding of nuclear activity is key. For instance, in a nuclear power station, managing radioactive activity is essential for safe and effective operation. In healthcare, radiation therapy employs radiation for cancer treatment, benefiting thousands annually. Ensuring safety and efficiency when dealing with radioactive materials hinges on understanding the behaviour and decay of atomic nuclei over time.

Subject Relevance

To Remember!

Concept of Radioactive Activity

The radioactive activity of a sample measures how rapidly its radioactive nuclei decay. It is defined by the number of nuclear disintegrations occurring per second. Activity directly reflects the intensity of radiation emitted by a radioactive sample.

• Activity is measured in Becquerels (Bq), with 1 Bq indicating one disintegration per second.

• Another unit is the Curie (Ci), where 1 Ci equals 3.7 x 10^10 disintegrations per second.

• As radioactive nuclei decay, the activity of a sample diminishes over time.

Units of Measure for Activity

The activity of a radioactive sample can be measured using two primary units: the Becquerel (Bq) and the Curie (Ci). Both units assess the decay rate of radioactive nuclei but on different scales.

• Becquerel (Bq): the standard unit in the International System (SI), correlating to one disintegration per second.

• Curie (Ci): a traditionally used measure, corresponding to 3.7 x 10^10 disintegrations per second.

• The choice of unit depends on the context and the magnitude of the activity being assessed.

Calculating the Activity of a Radioactive Sample

To calculate the activity of a radioactive sample, one must determine the decay rate of the existing nuclei, which involves using the half-life of the radioactive material alongside the initial number of nuclei.

• The fundamental formula for calculating activity (A) is A = λN, where λ signifies the decay constant and N represents the count of radioactive nuclei present.

• The decay constant (λ) can be computed from the half-life (T1/2) of the material using the formula λ = ln(2) / T1/2.

• Understanding the activity is key for practical applications like radiation therapy and ensuring nuclear safety.

Practical Applications

• In the healthcare field, radiation therapy adjusts the radiation dose according to the activity of radioactive material to treat cancer effectively.

• Nuclear power stations monitor the activity of radioactive substances to guarantee the safe and productive performance of reactors.

• In industry, assessing radioactive activity is critical for quality control and safety when handling radioactive materials.

Key Terms

• Radioactive Activity: Measure of the decay rate of radioactive nuclei in a sample.

• Becquerel (Bq): Unit of measure for radioactive activity, indicating one disintegration per second.

• Curie (Ci): Unit of measure for radioactive activity, corresponding to 3.7 x 10^10 disintegrations per second.

• Radioactive Decay: The process by which an unstable nucleus loses energy through radiation emission.

Questions for Reflections

• How does knowledge of radioactive activity contribute to advancements in technology and medicine?

• What challenges and responsibilities arise when working with radioactive materials?

• In which ways does an understanding of radioactive activity enhance safety and efficiency in nuclear power stations?

Simulation of Radioactive Decay

This mini-challenge aims to reinforce students' understanding of radioactive decay through a hands-on simulation using common materials.

Instructions

• Form groups of 3 to 4 members.

• Gather 100 glass or plastic beads and put them in a transparent container to represent the radioactive nuclei.

• Every 10 seconds, take out one bead from the container to simulate the decay of a nucleus.

• Keep track of the number of beads left in the container at each time interval.

• After 2 minutes, create a graph using the collected data (time vs. number of remaining nuclei).

• Examine the graph and discuss how the sample's activity diminishes over time.