Intro Lesson 1 Lesson 2 Lesson 3 Unit Test
Unit 4   header
Unit 1 Header

Lesson 3 Plan

How will the Yucca Mountain Repository Work?

Purpose:

This lesson will familiarize students with the planned design of the nuclear waste repository at Yucca Mountain, which includes both surface and underground facilities, and how it will be designed to protect people and the environment. Students will also learn of the operational steps for receiving the waste at the repository, preparing it for disposal, and placing it underground; and of the measures for protecting workers and the public during this phase.

Concepts:

  1. The repository at Yucca Mountain is designed to isolate nuclear waste deep underground for tens of thousands of years..

  2. The repository will include a system of specially designed underground tunnels for containing the waste.


  3. The repository design includes both natural and engineered features to restrict water from reaching the waste, breaking it down, and moving radioactive particles into the accessible environment.

  4. The repository will include aboveground facilities for preparing the waste to go underground. These facilities will have special features and controls to protect workers from the waste’s radiation.

  5. Repository facilities are designed to withstand earthquake damage and to provide safety for the work force.

  6. Workers will use remotely operated and/or shielded equipment to prepare the waste and to emplace it underground.

  7. Underground mining and engineering skills are necessary to provide adequate and safe construction of tunnels.

  8. The Department of Energy will monitor the repository for decades, and possibly centuries, to assure that it is safely isolating the waste.

Duration of Lesson:

Two 50-minute class periods

Objectives:

As a result of participation in this lesson, the student will be able to

  1. Describe and/or define the various aspects of the repository’s design, construction, and operation

  2. Explain why a repository must keep water away from the waste as long as practicable

  3. Describe the repository’s engineered features and how they will work with the natural system to isolate the waste for thousands of years

  4. Discuss plans for marking the repository, once it is closed

  5. Explain the radioactive waste handling process and the order of operations at the surface facilities

  6. List the order of operations for placing the waste packages into the underground tunnels

  7. Identify the safety and security processes that will be in place at the site

  8. Discuss plans for monitoring the repository

Skills:

Listing, describing, discussing, explaining, matching, reading, summarizing

Vocabulary:

Accessible environment, alloy, backfill, contamination, corrosion, drift, drip shield, emplacement, engineered features, invert, shielding, water table.

Materials:

Day 1:

Reading Lesson: "How Will a Repository Work?"

Activity Sheet: "The Repository Concept"

Day 2:

Activity Sheet: "Operations Flow Chart"

Activity Sheet: "Prework Hazard Survey"

DAY 1: The Repository Concept

Suggested Procedure:

  1. Allow 15 to 20 minutes for reading the lesson, How Will a Repository Work?

    Note: If students have access to the Internet, you may supplement the reading lesson by having students browse through the pages in the “About the Project” section on the Yucca Mountain Project web site at: http://www.ocrwm.doe.gov/ym_repository/about_project/index.shtml

  2. Go over the instructions for the activity sheet titled The Repository Concept and give students about 10 minutes to complete the exercise.

  3. Engage students in a discussion about the reading lesson and their answers on the activity sheet (see discussion points below).

  4. You may conclude this lesson with a discussion about the need for markers that would warn future generations of the location and hazards of the sealed geologic repository. Because the waste will remain radioactive for many tens of thousands of years, we need to assume that the types of controls we rely on today may not exist or be effective in the future. Our type of government could change, our language could become extinct, a use for the volcanic rock at Yucca Mountain could be found, etc. Therefore, the markers must communicate to future generations not to mine, drill, or dig in the area.


For class discussion:

  1. What is the purpose of a geologic repository?

    (The purpose of a geologic repository is to keep nuclear waste away from people and the environment for thousands of years by isolating it deep underground.)

  2. Why is it important to keep water away from the nuclear waste in the repository?

    (Water permits corrosion to occur and initiates transportation of radioactive particles. Over time, it could eventually break down the solid waste into tiny radioactive particles and then carry the particles into the environment.)

  3. What is the Exploratory Studies Facility? Why was it built?

    (The Exploratory Studies Facility is an 8-kilometer U-shaped tunnel under Yucca Mountain. It was built to provide scientists direct access for studying the underground area where the repository would be located. It will be used in the future to provide access to the underground emplacement tunnels.)

  4. What is the purpose of the emplacement tunnels?

    (The emplacement tunnels are where the waste will be permanently stored, about 300 meters below the surface of Yucca Mountain and 300 meters above the water table.)

  5. What are the basic considerations in selecting the layout and location of the underground emplacement tunnels?

    (The underground location of the emplacement tunnels is based on:

    • the thickness of the overlying rock and soil
    • the characteristics of the rock [such as porosity and rock strength]
    • the location of the fractures in the rock
    • the distance from possible earthquake faults
    • the depth to the water table
    • the heat output of the waste)

  6. What are the three main engineered features of the repository and how will they help isolate the waste?

    (The main engineered features are waste packages, drip shields, and inverts. The waste packages have corrosion resistant outer layers and are very durable, the drip shields will protect the waste packages from dripping water and rock fall, and the inverts will support the waste packages and may help restrict the movement of radioactive particles into the rock below.)

Note: Using the background notes titled: Waste Packages, you may describe the properties and importance of the waste packages in further detail.

Teacher Evaluation of Student Performance:

Completion of activity sheet and participation in class discussion will indicate understanding.

DAY 2: Repository Operations

  1. Divide students into small groups and give them a copy of the Operations Flow Chart activity sheet. Based on the reading lesson How Will a Repository Work?, give them about 15 minutes to create a flow chart showing the order of the steps required to place the waste in the underground repository— starting with receiving the waste and ending with final emplacement.

  2. Review the operations steps.

    (Repository operations include:
    1. Receiving truck and train shipments of nuclear waste.
    2. Transferring the waste from transportation casks to waste packages
    3. Sealing the waste packages
    4. Moving the waste packages underground
    5. Moving the waste packages into an emplacement tunnel
    6. Monitoring the repository’s safety)

  3. Engage students in a discussion about the different ways in which worker safety will be protected in each operational step.

    (In any step where the waste is not in a shielded container, such as a transportation cask, workers will be in separate rooms that shield radiation. They will use remotely operated equipment to perform the different waste-handling operations.)

  4. Describe to students the importance of protecting worker safety in hazardous environments. In addition to designing systems to protect safety, there are several other aspects of worker safety: training, safety practices, and hazard awareness. All workers at the repository receive many hours of safety training, depending on their specialty. Workers are required to follow strict procedures in every aspect of their job. Safety processes are more stringent as one gets closer to the core handling operations.

    The Yucca Mountain Project also fosters a culture called a safetyconscious work environment — one where every employee is encouraged to identify and raise safety-related concerns and issues. This requires a culture of open communication, where conflicts are identified, resolved quickly at the lowest possible level, or escalated promptly, if that becomes necessary. In this environment, all employees are free to identify and raise concerns and issues without fear of harassment, intimidation, retaliation, or discrimination.

    In addition, all working groups practice hazard recognition. That is, before starting a job, workers are expected to determine any potential hazards and ways to mitigate the hazards. In the safetyconscious work environment, a worker has the right to suspend work until the hazard is mitigated. Management must respond quickly to solve the problem.

  5. Go over the instructions for the activity sheet titled: Hazard Survey and give students about 10 minutes to complete the exercise. Explain that this activity is the same as that required of repository workers before performing their daily work or special tasks at the repository.

  6. Discuss the students’ answers on the activity sheet. Point out the importance of the workers themselves identifying hazards, rather than someone outside of the work process.

    Note: You may extend this activity to identifying potential safety hazards in your classroom or school and ways in which to mitigate the hazard. For example

    • Tripping hazards (electrical cords, boxes, desks, etc.)
    • Fire hazards (stacked papers, overloaded outlets, electrical equipment, etc.)
    • Health hazards (fumes, loud noise, bad lighting, etc.)

  7. Ask students why its important to public health and safety to monitor the repository.

    (The monitoring program will focus on the processes that are most important to repository safety [e.g., seepage and corrosion]. The program would include testing the repository environment [rock properties, chemistry, etc.] and verifying the data with the results predicted by computer models. If a problem is found, prompt action would be taken to mitigate the circumstances before they could become a larger hazard to public health and safety.)

Teacher Evaluation of Student Performance:

Participation in class discussion and completion of student activities will indicate understanding.

Enrichment Activities:

Model a Repository

Using Robotics in a Repository
The Waste Management System
The Waste Management System