In the first-ever gubernatorial veto of a presidential decision, Nevada Gov. Kenny Guinn (R) yesterday rejected George Bush’s proposal to build a nuclear waste repository at Yucca Mountain, 100 miles northwest of Las Vegas. Federal lawmakers granted the state veto power over any presidential decision related to Yucca Mountain in 1982; now, two decades later, Congress has 90 working days to override or sustain Guinn’s veto via majority vote. The outcome will determine whether the Bush administration can proceed with a plan to transport 77,000 tons of spent nuclear fuel and other highly radioactive waste to Yucca Mountain. Guinn and other opponents of the plan contend that the area is geologically unstable and that Nevada already stores more than its fair share of radioactive waste. But they are expected to have a tough go of it in Congress. It seems certain that the House will back the Bush plan, and the last time the Senate voted on a Yucca Mountain measure, only 32 Democrats sided with Nevada.