Lecture 16: Nuclear Energy and Radioactive Waste.

Control Rods?

( How is the Fission Reaction Controlled?) - materials that absorb neutrons.

Nuclear Fission?

(How do nuclear plants produce energy?) - Splits heavy atoms to make lighter atoms.

Neutron Bombardment?

(How does fission Occur). - U-235 fissions by neutron bombardment. - Neutron bombardment converts Uranium-238 (not fissionable) to Plutonium-239 (fissionable)

Yucca Mountain?

- Federal lands in southern Nevada. - DOE to study only Yucca Mountain Nevada to determine if suitable for radioactive waste repository

Waste Isolation Pilot Plant?

- Geologic repository for HLRW in SE New Mexico. - Waste stored in deep underground salt beds. Salt flow under pressure will seal off fractures and cavities from waste cask emplacement making them impermeable. - Began receiving waste in 1999 from military nuclear programs. •Continue to accept waste for several more decades before closure.

High level radioactive waste?

- High-level waste: spent nuclear fuel, fission products • Federal government retains responsibility for high-level waste. - Fission fragments of U-235decay to stable isotopes relatively quickly.

What is the Yucca Mountain Project? What characteristics make the Yucca Mountain site a good location for the federal radioactive waste repository? What characteristics make it a poor location?

- In 1983 The US Department of Energy initiated the Yucca Mountain Project to determine if the location is suitable for the amount of high level of waste repository.. - The location is sparsely populated, it is owed federally owned, the climate is favorable because it is dry, it is in a closed drainage basin, and low contamination flow in groundwater. - The fractures in the host rock may enable a fast groundwater flow, recent earthquakes, and volcanic activity, the problem of the unresolved Native American land claims, there are endangered species, and the local opposition by Nevadans.

Low level radioactive waste?

- Low-level waste: materials that have contacted nuclear fuel (clothing, equipment), uranium mine tailings. •licensed by states under authority delegated by Congress in 1985 •States responsible for low level radioactive waste

Is nuclear fuel reprocessing a better option than disposal? Explain why or why not?

- Nuclear fuel reprocessing is better than disposal. The nuclear fuel reprocessing is the recovery of remaining fissionable materials for use as fuel. Nuclear fuel reprocessing allows different nuclear materials to be managed differently. Conserves supply of fissionable material and is used to recover plutonium for nuclear weapons.

Describe the process of nuclear fission, and be sure to explain how the energy released by nuclear fission is harnessed to produce electricity. How is the fission reaction controlled in a nuclear reactor?

- Splits heavy atoms to make lighter atoms. U-235 Fission by neutron bombardment. The free neutron strikes U-235 Nuclear causing fission, releasing energy. - Fission converts the small amounts of mass into large amounts of energy. - The energy (heat) is used to boil water and it makes steam, the turbines turn and generate electricity. -controlled by limiting free neutrons in the reactor, control rods used to absorb neutrons and slow reactions.

Fissionable Material?

- The elements uranium-235 and plutonium, whose atoms split apart and release energy via a chain reaction when an atomic bomb explodes.

What is the WIPP and how is it different from Yucca Mountain?

- WIPP is Waste Isolation Pilot Plant, geologic repository for HLRW in SE New Mexico. WIPP stores waste in deep underground salt beds. Once emplaced cannot be retrieved.

Breeder Reactor?

- contain fertile material such as U-238 that can be converted to fissionable material.

Burner Reactor?

- use more fissionable material than they produce.

How does a breeder reactor differ from a burner reactor?

-Breeder reactors: contain fertile material such as U-238 that can be converted to fissionable material. Makes more nuclear fuels than it burns. Burner reactors: use more fissionable material than they produce.

Renewable Energy?

A resource that has a theoretically unlimited supply and is not depleted when used by humans.

Alternative Energy?

Any source of energy other than fossil fuels that is used for constructive purposes.

Uranium Enrichment?

Increase Uranium-235 to 3%. Minimum needed to sustain fission reaction. - Only naturally occurring fissionable isotope is U-235. - Uranium-238 not fissionable

What is the current status of the Yucca Mountain Project? What went wrong and why?

The Yucca Mountain Project is currently on hold and may never happen. The Obama administration withdrew project funding for it in 2010. It mostly went wrong because the selection of nuclear waste for the disposal site is highly contentious. The local support for the project is critical, especially since the project has been going on for decades. - In 2010, the Obama administration withdrew project funding. The selection of the nuclear waste disposal site is highly contentious.