Updated

Chronic electrical surges at the massive new data-storage facility central to the National Security Agency's spying operation have destroyed hundreds of thousands of dollars worth of machinery and delayed the center's opening for a year, according to project documents and current and former officials.

There have been 10 meltdowns in the past 13 months that have prevented the NSA from using computers at its new Utah data-storage center, slated to be the spy agency's largest, according to project documents reviewed by The Wall Street Journal.

One project official described the electrical troubles—so-called arc fault failures—as "a flash of lightning inside a 2-foot box." These failures create fiery explosions, melt metal and cause circuits to fail, the official said.

The causes remain under investigation, and there is disagreement whether proposed fixes will work, according to officials and project documents. One Utah project official said the NSA planned this week to turn on some of its computers there.

NSA spokeswoman Vanee Vines acknowledged problems but said "the failures that occurred during testing have been mitigated. A project of this magnitude requires stringent management, oversight, and testing before the government accepts any building."

More On This...

Read more at The Wall Street Journal.