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A massive steam generator finished its slow crawl through California, Nevada and Utah this week, arriving at a low-level nuclear waste site 70 miles west of Salt Lake City.

It took 15 days to make the 852-mile trek from Southern California's San Onofre nuclear power plant. The 400-ton generator was hauled a trailer longer than a football field, driving no faster than 25 miles per hour.

The trailer took up two-plus lanes of traffic and was followed by a convoy of law enforcement vehicles. It traveled by night in California and by day in Nevada and Utah.

Officials said the slightly radioactive steam posed no health hazard, and that someone standing next to it for an hour would get a dose of radioactivity about the same as a dental X-ray.