The Nuclear Regulatory Commission, in what it called an unprecedented action, yesterday proposed a $225,000 fine against the Niagara Mohawk Power Corp. and ordered the firm to remove an employe from all nuclear work. The NRC charged the company with lying about its failure to install safety equipment at the Nine Mile Point plant near Oswego, N.Y.

In a letter to Niagara President William J. Donlon, NRC Inspection and Enforcement Director Victor Stello ordered that former Nine Mile site superintendent T. J. Perkins be prohibited from further nuclear responsibilities beginning immediately. The order also directed the utility to show cause why Executive Vice President James Bartlett should not be similarly banned from nuclear power work.

NRC spokesman Karl Abraham said Perkins was supervisor of the 11-year-old plant on Jan. 22 when Bartlett affirmed in a letter that a new high-level radiation monitor had been installed in the plant's smokestack. "We alleged that Perkins provided the information, that he knew it was not correct and that Bartlett not only signed the letter, but formally affirmed its validity," Abraham said.

He added that the NRC had never before ordered a company to remove an employe from a particular job.

Niagara Mohawk spokesman Edward Kaish said the firm considered the charges "very serious" and would comply with the order but would have no comment on it until it had been studied.

The monitor was ordered installed at all nuclear power plants no later than last Jan. 31 as one of a number of changes required in the wake of the 1979 accident at Pennsylvania's Three Mile Island plant, where radiation monitors designed to measure low-level releases were pushed past their capacities and measurements of radiation emitted were uncertain.

However, in a health-physics inspection Oct. 8, the NRC found no trace of the monitor at Nine Mile Point. It was subsequently installed.

The company may protest the proposed fine and has the right to ask for a public hearing on the order.