EDITORIAL QUESTIONS ABOUT YUCCA REPLACING ONE RISK WITH ANOTHER.

YUCCA Mountain, Nev., which is remote, arid and virtually impenetrable, seems like a good place to store highly radioactive and dangerous nuclear waste.

The San Fernando Valley and Ventura County, on the other hand, which are covered with densely populated housing tracts, are perhaps the worst possible areas through which to transport it.

And therein lies the problem with the Yucca Mountain Project, which the U.S. Senate endorsed last week.

The product of 20 years of study and $4 billion in research, the project is supposed to be the solution to the ongoing threat to public safety and national security resulting from the accumulation of spent nuclear fuel and high-level radioactive waste at various facilities throughout the country. Hazardous materials would be shipped to the Yucca Mountain facility, where they would be stowed in sealed containers beneath thousands of feet of rock.

The idea is, in theory, a good one. Because the United States has never had a long-term repository for nuclear waste, materials have been allowed to pile up at facilities across the country, where they could either leak or get into the hands of terrorists looking to create a dirty bomb. By putting them in one secure location, government officials would be better able to minimize the potential risks.

The danger is getting the waste there.

Under the current plan, most of the material would pass through highly populated areas - like the Valley and Ventura County.

Not to worry, the feds say. Nuclear waste is carted around all the time, and there have never been any serious incidents. The lead-lined steel containers used to transport the waste won't crack, even when dropped or burned, they assure us.

But local residents need only look at the contaminated site that once was the Rocketdyne facility in the Simi Hills for a reminder that when it comes to matters of local environmental safety, Washington's word isn't always a guarantee.

And it only takes one accident to make a good idea in theory turn into a nightmare in reality.

In June, the Environmental Working Group released a study of what could happen if there were a ``moderate'' nuclear-waste accident in some 20 major American metropolitan areas, including Los Angeles. Assuming a train traveling between 30 and 60 mph crashed and released cesium in the Northridge area, EWG predicted that some 223,942 local residents would be exposed to radiation, and as many as 896 would die. Cleanup costs, according to the study, could run between $10 billion and $150 billion.

Statistics like those give us pause.

There's an undeniable need to move the nation's nuclear waste to a safer location. But isn't there a better a way to get it there?