CE 3231 - Introduction to Environmental Engineering and Science

Readings for Next Class:

Ohio Northern University

Introduction Chemistry, Microbiology & Material Balance Water & Air Pollution Env Risk Management

Nuclear Chemistry

Radiation occurs naturally all around us. In this class we will cover the three types of radiation along with nuclear fission (used to make power). We will take a look at calculating half-lives and also the most common units to describe radiation dosing.

Lecture 9Nuclear Chemistry

(Chemistry VI)

Arsenic in Bangladesh Review

Radiation Three types released from unstable nucleus

alpha

beta

gamma

2 protons, 2 neutrons

electron or positron

electromagnetic radiation

Ionizing Radiation

a, b and g carry enough kinetic energy to liberate an e- from an impacted particle…

A note about x-rays:

X-rays are ionizing radiation (really like gamma rays), but they are generated by electron transitions rather than from an unstable nucleus

..therefore shielding is important!

Radiation Units

• curie (Ci)decay

• becquerel (Bq)decay

• roentgen (R)ionizations

• rad (radiation absorbed dose)dose

• rem (roentgen equivalent man) equivalent dose

Nuclear Fission

Reaction gives off particles with kinetic energy. The KE builds within the uranium fuel pellet resulting in heat gain within the pellet. The heat is transferred to water through the fuel rod (metal tube)

Include: Ce-137

Sr-90

I-131

Making Uranium Pellets

Uranium Mining and Milling

Making Power

How a Nuclear Power Plant Works

Managing Radioactive Waste

Wastes

Radioactive Decay – The challenge

Radiation fragments in waste (Ce-137, Sr-90, I-131) will continue to give off ionizing radiation and must be safely shielded and stored for a very long time.

N = Noe-0.693t/t

Estimated by:

where:

N = final number of atoms or curiesNo = initial number of atoms or curiest = timet = half-life of atom

Radioactive Decay – The challenge

ElementHalf Life

Ce-137

30.17 years

Sr-90

28.79 years

I-131

8.01 days