WASHINGTON -- The top Yucca Mountain manager on Wednesday defended the Energy Department's spending of more than $25 million to restore the project in the wake of scientists' e-mails that raised questions about research quality at the nuclear waste site.

"An objective individual taking a look at this should, if nothing else, see that DOE spent a heck of a lot of effort" on corrective action, including searches to determine whether similar problems lurked elsewhere in the program, said Ward Sproat, director of the Office of Civilian Radioactive Waste Management.

Sproat confirmed a $25.6 million price tag reported by the Government Accountability Office in a study released this week. He said the numbers were generated by DOE and given to the auditors as "a best estimate of the work."

Much of the money already has been spent on investigations and corrective actions that began in 2005. About $5 million is scheduled to be spent this year to complete the tasks, the GAO said.

On Wednesday, Yucca opponent Rep. Jon Porter, R-Nev., said the Energy Department was "throwing good money after bad" in trying to fix problems at the proposed waste repository that has been chronically delayed.

Rep. Shelley Berkley, D-Nev., circulated a letter to other House members calling attention to new criticism of the repository leveled last week by Edward McGaffigan, a departing member of the Nuclear Regulatory Commission.

Sproat, appointed by President Bush last year to manage the repository site, said his charge was to fix the project and move it forward.

"I can't make excuses or really talk about what went on in the past and the problems that occurred," he said. "I can talk about what I am doing now and that I am aware of the quality problems that existed."

The Energy Department launched a multipronged investigation after the discovery of e-mail messages in which several U.S. Geological Survey hydrologists assigned to Yucca indicated they may not have followed quality assurance requirements for a water infiltration computer model they were building.

The messages were written between 1998 and 2000 but not discovered until 2004 and not disclosed until March 2005.

The GAO report detailed costs to sample and review more than 14 million e-mails, to provide quality assurance training, and to replace the infiltration model that had been called into question.

After reviewing that model and others the hydrologists had helped build, Energy Department officials declared scientific data had not been compromised but quality assurance standards had not been met.

Engineers from Sandia National Laboratories were brought onto the Yucca program to reconstruct the model, a key piece of research of how water might seep into the mountain and over thousands of years rust canisters of highly radioactive spent nuclear fuel.