As late as 1976, after the activities of the acknowledged world uranium cartel supposedly had ended, a U.S. sales representative for Nufcor, the South African members of the cartel, was soliciting business under the Carter's rules, douments made public here today suggest.

Letters sent out on Jan. 12, 1976 by the Philipp Brothers Division of Engelhard Minerals and Chemicals Corp., Nufcor's agent, notified other cartel members in mining operations that Westinghouse Electric Corp. would not get any uranium if Philipp Brothers was their sales agent.

"It is our view that contract negotiations for sale of (uranium) be entertained only with end users, e.g., to avoid sales to reactor vendors and/or manufactures of fuel components," John F. Lee, Philipp Brothers vice president wrote them. "Our experience in sales to other than end users has usually resulted in creating additional unnecessary competition."

The documents were submitted in U.S. District Court here as part of Westinghouse's defense for its announcement two years ago that it was no longer able to fulfill its long-term uranium supply contracts with more than two dozen utilities.

Westinghouse, which sold the uranium along with nuclear reactors, said it was excused from fulfilling the contracts under a section of the Uniform Commercial Code because unforeseen events had occurred making fulfillment "commerically impracticable."

Among other things, Westinghouse cited the activities of the cartel as one of the unforeseen events that pushed the price of uranium from $8 to $12 called for in the contracts to $26 a pound at the time of its announcement. This case pits a dozen utilities agaist Westinghouse.

Although cartel members claim that their activities excluded the United States, Westinghouse is attempting to show that their activities did have an impact on domestic prices and on Westinghouse's ability to secure the uranium it needed to meet its contracts.

In documents presented to the court today, Lee, operating in New York on behalf of Nufcor, appears to know about the "club" as the cartel was often called, and its rules at least since June 8, 1972.