Sen. Edward Zorinsky (D-Neb.), chairman of the senate hemisphere affairs subcommittee, announced yesterday that he will visit Nicaragua Sunday for a brief fact-finding tour of conditions in the wake of the recent Sandinista victory there.

Zorinsky, who tentatively expects to return here Tuesday, said he has assurances of a meeting with the revolutionary, five-member Nicaraguan junta and plans to assure them of U. S. desire to work with them "if they are willing to work with us."

In June, Zorinsky publicly called for the United States to force the ouster of President Anastasio Somoza, Nicaragua's longtime dictator, on the grounds he had lost the support of the Nicaraguan people. The Carter administration subsequently took the leading role in pressuring Somoza to resign.

Elsewhere yesterday, the State Department denied that Viron P. Vaky, assistant secretary for inter-American affairs, has said or implied that the El Salvador government of President Carlos Humberto Romero is unwilling to make reforms aimed at heading off a civil war in that Central American county.

In an article published yesterday The Washington Post said Vaky, who visited El Salvador last week, had concluded that the polarization between Romero's rightist government and leftist guerrillas could produce a replay of the Nicaraguan situation.

However, department spokesman Tom Reston said Vaky had not concluded that the Romero government is unwilling "to make concessions toward liberalization." Although Reston said he could not go into specifics, he added that Vaky had "significant discussions" in El Salvador and had been assured of the Romero government's willingness to make "real reforms."

The Post also reported that there is a debate underway within the administration about whether the United States should resume military aid to El Salvador and Guatemala.