The chairman of the Senate Judiciary Committee, citing new evidence of a U.S.-Canadian coverup, yesterday announced plans to file suit in an effort to force the Justice Department to surrender internal documents in the investigation of a worldwide uranium cartel.

Sen. Edward M. Kennedy (D-Mass.), along with Sen. Howard Metzenbaum (D-Ohio), chairman of the Senate antitrust subcommittee, are seeking information behind Justice Department's decision not to seek felony indictments against five U.S. companies allegedly involved in the cartel.

Specifically, Kennedy and Metzenbaum want the information behind the decision by John Shenefield to override the recommendations of his staff attorneys to seek an indictment.

At subcommittee hearings in March, Shenefield acknowledged that he overturned his staff recommendation, but refused to turn over the documents, contending they were protected as grand jury workproducts.

Justice had presented the cartel case before a grand jury for two years. But the grand jury was disbanded in June 1978, and the department filed only a misdemeanor charge against Gulf Oil Co., which paid a $40,000 fine.

Kennedy staffers say, however, that their investigation has revealed overcharges of at least $3 billion.

And, the staffers say, they have new evidence that the State Department and the Canadian government applied pressure on the Justice Department not to seek felony indictments against the companies involved. The Australian, Canadian and French governments were said to be part of the cartel.

The price of uranium jumped from $4.50 a pound in 1972 to $40 a pound in 1976, the time period allegedly covered by the cartel.

Despite Justice receiving extra funds and subpoenaing a dozen firms, Gulf was charged only with a misdemeanor because its Canadian subpoenaing a dozen firms, Gulf was charged only with a misdemeanor because its Canadian subsidiary got out of the cartel the day before price-fixing became a felony.