JUST HOURS into his tenure as a member of the Nuclear Regulatory Commission, James K. Asselstine provided a nice lesson in public service. Standing up to intense pressure from the administration and the nuclear industry, Mr. Asselstine cast a key vote in which he placed his own "independence and objectivity, and that of the commission" above what he had clearly been appointed to accomplish.

Hanging in the balance was an ill-advised administration attempt to secure a special exemption from the NRC's licensing requirements for the troubled Clinch River Breeder Reactor. The case against wasting more money on this breeder demonstration program was becoming harder and harder to ignore, and the Department of Energy feared that unless it could show that construction was actually under way, Congress would finally kill the program this summer.

But there was a problem: the breeder had not yet passed the NRC's licensing examination, which meant that construction could not begin. So DOE asked for the exemption. In March, the NRC denied the request by a vote of 3 to 2. There was still hope though, since one commissioner who had voted "no" was about to leave. Administration officials and Chairman Nunzio Palladino vowed to find a right- minded replacement.

Under the NRC's rules, the decision could be reconsidered without new evidence until Monday, May 16. Mr. Asselstine's nomination was rushed through the Senate. He was confirmed last Thursday. On Friday, DOE formally requested reconsideration. Mr. Asselstine was sworn in Monday at 11 a.m., and Chairman Palladino called a meeting to reconsider the exemption request for 3 o'clock.

But here Mr. Asselstine's clear sense of how an ostensibly independent regulatory agency should operate upset the plan. Noting that DOE was requesting "extraordinary relief," he pointed out that his vote to approve could give "at least the appearance of a hasty and ill-considered judgment," and he voted "no."

DOE can still try to come up with new evidence and ask the commission to start the whole process over. Mr. Asselstine might then vote in favor-- though we believe that is unlikely if he brings the same objectivity to consideration of the merits as he has to proper process. However it turns out, we salute his first move.