## How long to reach secular equilibrium?

There is a rule of thumb regarding how long it takes to reach equilibrium: Transient equilibrium is reached in ~4 daughter half-lives. For Tc-99m, predicted length of time is 24 hours; actual time to equilibrium is 23 hr. Secular equilibrium is reached in ~6 half-lives of daughter.

What is meant by transient equilibrium?

In nuclear physics, transient equilibrium is a situation in which equilibrium is reached by a parent-daughter radioactive isotope pair where the half-life of the daughter is shorter than the half-life of the parent.

Definition of radioactive equilibrium : the condition in which a radioactive species and its successive radioactive products have attained such relative proportions that they all disintegrate at the same numerical rate and therefore maintain their proportions constant.

When a daughter radionuclide has a half-life longer than that of a parent there is equilibrium?

secular equilibrium generator
Another type of generator is called the “secular equilibrium generator”; where the half-life of the parent is much longer than the half-live of the daughter. The parent will not decay noticeably during many daughter half-lives. This situation is called “secular equilibrium” (See Figure 2).

## What is the half-life of Mo-99?

66 hours
Because of its relatively short half-life (66 hours), Mo-99 cannot be stockpiled for use. It must be made on a weekly or more frequent basis to ensure continuous availability. The processes for producing Mo-99 and technetium generators and delivering them to customers are tightly scheduled and highly time dependent.

What is the half-life and energy of technetium 99m?

The metastable technetium-99m (99mTc) is a short-lived (half-life about 6 hours) nuclear isomer used in nuclear medicine, produced from molybdenum-99….Technetium-99.

General
Natural abundance trace
Half-life (t1/2) 211100±1200 years
Spin 9/2+
Excess energy −87327.9±0.9 keV

### What is transient and secular equilibrium?

Transient: impermanent, transitory, short-lived, momentary, ephemeral. Secular: of or relating to a long enduring process; requiring or taking ages. In the context of radioactivity, equilibrium defines a bal- ance between the rate of formation of a radioactive product, and its rate of decay.

What is the importance of radioactive equilibrium?

In this case the production rate and decay rate of certain member of decay chain cannot be equal. Secular radioactive equilibrium exists when the parent nucleus has an extremely long half-life. This type of equilibrium is particularly important in nature.

## How does radioactive equilibrium differ from chemical equilibrium?

In radioactive equilibrium, the rate of decay of nuclei is equal to rate of integration of nuclei. In chemical equilibrium, the rate of decomposition of molecules is equal to the rate of combination of molecules.

What is the half-life of Mo 99?

### How does technetium-99 work?

Technetium-99m decays by a process called isomeric transition, a process in which 99mTc decays to 99Tc via the release of gamma rays and low energy electrons. Since there is no high energy beta emission the radiation dose to the patient is low.

What is the difference between technetium-99m and technetium-99?

Technetium-99 is produced during nuclear reactor operation, and is a byproduct of nuclear weapons explosions. Technetium-99 can be found as a component of nuclear waste. Technetium-99m is a short-lived form of Tc-99 that is used as a medical diagnostic tool.