Van Luik and other DOE scientists conceded that there are many gaps in the scientific knowledge of how Yucca Mountain will perform as a repository over the long haul. Sufficient information could take 125 or more years to gather, van Luik said. Between sessions in the hallways, van Luik, board members and others conceded that currently the evidence for building a repository at Yucca Mountain is thin. Scientists still don't know what happens over time to Yucca's rock when heated as it would be by radioactive waste buried inside. Nor do they know where the small amount of ground water that flows through the mountain goes and whether water deep within the mountain could rise to the repository's level.
Ground water poses a danger of corroding containers holding the radioactive waste.
The DOE will have to prove to the Nuclear Regulatory Commission that radiation will not escape in ground water or the air for 10,000 years. If a repository is built, the DOE wants Congress to fund studies for up to 125 years to monitor the buried wastes. Whether Congress provides that money is a great concern, van Luik said. No one knows what the final design of a Yucca repository would look like, since studies still have not identified all of the potential problems. The DOE presented little more than sketches of the enormous gaps scientists face in explaining how Yucca will keep radiation from commercial reactor and nuclear weapons wastes away from people and the environment.