Yucca Mountain Deep Repository Michael Hynd

Yucca Mountain Repository Proposed Deep Geological Repository Storage facility for spent fuel and high-level radioactve waste (nuclear power and defense) Would be the USA’s first long term repository of this type Aim is to provide storage for waste currently stored at 126 temporary individual sites providing a capacity of 70,000 metric tons

Location Yucca Mountain is a ridge line in the south-central part of Nevada, composed of volcanic material ejected from a now-extinct caldera-forming supervolcano It is in a remote desert within the secure Nevada Test Site in Nye County Approximately 100miles northwest of Las Vegas

The Exploratory Studies Facility A US-Department of Energy underground laboratory at Yucca mountain Constructed between , to allow scientist and engineers to study the rock properties and water behaviour near the proposed repository area Data is collected to verify models and predictions about the geology and hydrology surrounding the area. The purpose of these studies at Yucca Mountain was to determine whether the site is suitable for a high-level radioactive waste and spent nuclear fuel repository

The studies known as site characterisation were divided into 3 parts: –Surface-based testing, which includes analyzing rock, soil samples, and water movement –Underground testing, which includes examining rock at deep levels –Laboratory analyses, which encompass analyzing liquid and gas from rock samples collected from surface-based and underground test activities The Exploratory Studies Facility

Proposed Repository Engineering and Design 1: Canisters of waste, sealed in special casks, are shipped to the site by truck or train 2: Shipping casks are removed, and the inner tube with the waste is placed in a steel, multilayered storage container. 3: An automated system sends storage containers underground to the tunnels 4: Containers are stored along the tunnels, on their side

Design Factors The main safety concerns were: –preventing water from reaching the waste canisters –limiting the rate that canisters and waste could be dissolved by water –slowing or filtering out radioactive particles as they move away from the repository

Multi-Barrier Therefore a ‘Multi-barrier’ approach was used to isolate the waste, located around 1000 feet below ground level and about 1000 feet above water table: –Natural Barriers: The mountain, soil, rock, and other natural features of the mountain that prevent/limit water from reaching waste packages deep underground in the repository. Natural barriers also prevent or limit the amount of dissolved waste that could reach the environment where people live. –Engineered Barriers: man-made components of the repository designed to help the site’s natural features protect the waste packages from water i.e waste containers, the design of the repository and additional equipment to cover and protect the waste package from damage.

Natural Barrier Yucca Mountain was created by several large eruptions from a caldera volcano and is composed of alternating layers of ignimbrite (welded tuff), non-welded tuff, and semi-welded tuff Tuff has special physical, chemical and thermal characteristics that some experts believe make it a suitable material to entomb radioactive waste for the hundreds of thousands of years required for the waste to become safe through radioactive decay

Natural Barrier Some critics have expressed concern over the possibility of fault lines and fractures in the rock providing a route for the movement of radioactive waste to be dissolved in water flowing downward from the surface However the waste containers have been designed to be stored in such a way as to effectively eliminate this possibility

Engineered Barrier Spent fuel rods will be placed in a canister called a Transportation, Aging and Disposal (TAD) canister Prior to leaving a facility for Yucca Mountain, the TAD would be placed in a transportation cask, which is radiation-shielded, sturdy, and impact-resistant. The packages would be shipped primarily by train At the Yucca Mountain site, the TADs would be removed from the transportation cask and placed in aging or emplacement packages. The TAD canister transfer takes place inside surface facilities using remote-controlled equipment. Disposal canisters

TAD canisters that need to cool off, or age, before going into the repository will be placed in aging canisters and stored on aging pads located near the waste handling facilities TAD canisters ready to go directly into the repository will be placed in an additional, corrosion- resistant disposal package.

Emplacement Tunnels The specially constructed horizontal openings where the waste will be placed for disposal Lined with perforated steel plates held in place by rock bolts to prevent rock from falling on the engineered features The tunnels would be 18 feet in diameter and about 250 feet apart the tunnels are designed so that any water that enters them will drain, by gravity, downward and away from the repository

The results of extensive underground tests indicate that very little water could seep into the repository tunnels. Instead, most water flows around the openings.

Self-propelled emplacement robot An electric transporter called a Transport and Emplacement Vehicle (TEV) will transport the waste package to the emplacement tunnels. The TEV travels from the surface facility, enters the main tunnel and moves each loaded waste package to an emplacement tunnel

Surface Facilities Receipt Facility – waste canisters are removed from the transportation casks and prepared for transfer to the appropriate waste handling facility. This facility also prepares unloaded transportation casks and railcars for return to the National Transportation System for continued use. Initial Handling Facility – would prepare high-level radioactive waste from government facilities and spent nuclear fuel from the U.S. Navy for disposal. Canister Receipt and Closure Facilities – would receive all disposable canisters, and prepare them for disposal. Wet Handling Facility – A small percentage of spent nuclear fuel will not arrive at the repository in TADs, but will be shipped in transportation casks designed to handle individual assemblies of spent fuel rods. The Wet Handling Facility includes a pool of water in which spent fuel rods are removed from transportation casks, placed into TAD canisters and prepared for disposal or aging.

Future Generations The repository design allows for future generations to close and seal the repository or to keep it open and monitor it for up to 300 years before decommissioning and closing the site. The design allows for removal of the waste from the repository in case future technologies provide a better disposal solution or a use for the nuclear materials Post-closure activities would include controlling the land and its boundaries, monitoring and testing the surrounding environment, and implementing safeguard and security measures for future generations The environment at the site would also be returned to as close to its original state as possible

Opposition The project is widely opposed in Nevada and is a hotly debated national topic Nevada Senator Harry Reid has been a long time opponent of the repository and has stated his intention to work to block completion of the project According to Native Americans, the Yucca Mountain area is part of their holy lands and there has been a lawsuit filed, challenging the United States' right to store nuclear waste in Yucca Mountain Due to these factors the repoisitory is not expected to open before 2017, and The U.S. Department of Energy does not anticipate submitting a repository license application to the Nuclear Regulatory Commission until mid-2008