What New Hampshire really wants, said Leni Sitnick of the governor's task force on nuclear trash, is pretty much what most states want: that it should go somewhere else.

But a decision on which states get stuck with America's low-level radioactive waste is being forced on the nation's voters and state legislators right now, before most of them are ready.

Like toxic chemicals and prisons, low-level nuclear waste is a distasteful but inevitable part of modern life.

Federal rules establish three categories of nuclear waste and spell out how it must be treated:

Low-radiation items like rags, gloves, tools and bootees used in research facilities or reactor sites can be buried in trenches.

Middle-level junk like research animal carcasses and used tracer chemicals require monitoring in lined and closed pits.

Highly radioactive material containing cobalt and Cesium 137--such as worn-out reactor parts, used water filters and sludges from reactor cooling systems--must be isolated in glass and held in clay-lined pits for 300 years.

There now are only three disposal sites--in Hanford, Wash., Beatty, Nev., and Barnwell, S.C.--and they cannot handle the growing piles of radioactive trash forever. Three earlier sites in Illinois, New York and Kentucky were closed permanently because of water infiltration and erosion.

The states have a federal deadline, Jan. 1, 1986, for dealing with nuclear low-level junk.

Under the Low Level Nuclear Waste Policy Act of 1980, states that organize themselves into regional nuclear-dump compacts can bar shipments from outside states after that date. Any state not in a compact will have to build its own disposal site to have somewhere to put its nuclear trash after 1986.

Five of the six compacts are expected to be ratified by the required three state legislatures by the end of this month and sent to Congress for approval this summer. Senate Judiciary Committee hearings on the compact process begin today.

Three of those five compacts--Northwest, Southeast and Rocky Mountain--are organized around the three existing sites. The other two potential compacts--Central and Midwest--have no sites and must build them.

The laggard region is the Northeast--Maryland and 10 other states--which produces 35 percent of the nation's low-level radioactive trash.

After 18 months of talks the states managed to come up with a proposed compact at a meeting in Boston on Feb. 18. But the region has a long way to go, and is more likely to founder than to meet the deadline.

One problem is that some states produce a lot of nuclear trash, while others, such as New Hampshire, produce very little. Even counting future waste from the controversial Seabrook nuclear power plant, still under construction, New Hampshire will produce only enough hot garbage every year to fill two-thirds of a boxcar.

But by joining the Northeast compact it could someday be the host for the region's yearly 31,000 cubic meters of waste, enough to fill 225 boxcars.

"The fundamental principle of a compact is that every state volunteers to be a host state someday," said Wayne Kerr of the Nuclear Regulatory Commission's office of state programs.

Realistically, many assume that the states with major waste production, central locations and experience in handling and regulating the stuff are the most likely to wind up with a major site.

That means Pennsylvania and New York, as their officials acknowledge. But for political reasons it cannot be spelled out in the compact, and that makes everyone nervous.

"It's a calculated risk," said Mark Candon, a Vermont state representative, at the Boston meeting. "You join hoping that by the time it's Vermont's turn in 20 or 40 years maybe they'll have figured out some other way to do it."

But if New Hampshire opts to build its own site, new federal regulations mean that even a small one will cost several million dollars. The state's small waste volume could not possibly generate enough users' fees to underwrite such a price.

Further, if New Hampshire did build a dump, the law is unclear on whether it could bar other orphan states from using it.

"They've got us going and coming," said social science teacher Madelyn Barber of Walpole, at a citizens meeting here. Like many others, she said she remains worried about the leaky history of waste dumps, even though technical experts say all the old problems have been solved. "All the previous promises have been broken," Barber said.

Even New Hampshire Gov. John Sununu--a pro-nuclear Republican who looks wistfully at the industries and jobs that a convenient nuclear trash site might attract--says granite subsoil, heavy rainfall and high tourist trade make New Hampshire a bad site.

"Tourists depend on the perception of this state . . . and there might be a perception that a site is a negative factor," he said in an interview.

Some states look for tradeoffs: Pennsylvania delegates hinted that if another state promised to open a hazardous chemical waste site Pennsylvania might take the nuclear trash.

The Northeast pact is also shaky because federal law requires that all states in a compact must agree to identical terms. Yet negotiators for New York, Massachusetts and Pennsylvania expect their legislatures to amend the pact, forcing it to be renegotiated.

In addition, Massachusetts voters approved a law in November that requires any pact and any waste site to pass a statewide referendum at a general election. But officials don't see that as a problem.

Maine tried to win a guaranteed exemption from a site for low-volume states, and its officials now indicate that they would seriously consider joining New Hampshire in a mini-pact, possibly with Vermont.

To work all this out will take awhile. Asked if a Northeast dump can be set up by the 1986 deadline, New Hampshire negotiator Arnie Wight said, "Oh, no. Add five years to that."

Other delegates agreed, saying they hoped Congress or a state with a site, like South Carolina, would take pity on the Northeast if it has at least made some progress.

Environmentalists and other observers at the Boston hearing, including Leni Sitnick of New Hampshire, said they worried about the rush to get it all decided.

"This has been like a game show where people have to quickly push a button and vote," she said. "There ought to be more time to do it right."