President Reagan gave renewed hope Monday to civilians in Utah, Nevada and Arizona who were affected by radioactive fallout during atomic bomb testing, by signing a bill to help military veterans obtain compensation for alleged test-caused illnesses. A new bill to compensate downwind victims is being readied in the House and Senate and its sponsors, Sen. Orrin Hatch, R-Utah, and Rep. Wayne Owens, D-Utah, hope to introduce it soon.

Victims of the weapons tests more than 30 years ago won a court victory in Federal District Court in Salt Lake City but were rebuffed by the Court of Appeals in Denver. The U.S. Supreme Court refused, in January, to hear the case, citing the government's immunity from suit for "discretionary" functions.The veterans who participated in testing, or who were assigned to duty at Hiroshima or Nagasaki in 1945, were granted a presumption that certain types of illnesses, primarily cancers, were service-connected and thus eligible for Veterans Administration aid.

The Hatch-Owens bill would recognize a limited number of cancers as radiogenic and grant up to $300,000 in compensation to victims or heirs of those who lived in the area during the tests and later developed cancers. Others who lived in the area and became ill with what they believe to be fallout-caused illnesses would be given the right to sue the U.S. without permitting the U.S. to cite the "discretionary function" defense.

A new statute of limitations would be established for the fallout cases, giving those who felt they were hurt two years from the date of enactment of the legislation, or two years from the date they determined they were ill, whichever was later, to bring suit against the U.S.

Hatch and Owens were attempting this week to work out details of the bill, with Owens seeking to expand the types of cancer to be granted direct compensation, while reducing the cap on benefits to $150,000.

All administrations since the tests were halted in 1962 have opposed compensating test victims and Monday's signing of the veterans' bill indicated a change in that policy by the Reagan administration.

Congress voted this year to compensate interned Japanese civilians of World War II, as well as the veterans of atomic bomb tests.