With the bulk of their Year 2000 computer fixes made, federal agencies are increasingly focused on developing emergency backup plans that will keep their doors open for business if they encounter any Y2K glitches that interfere with operations.

The importance of contingency planning was underscored Friday, when federal systems began a new fiscal year and four agencies discovered some bugs that were fixed the same day.

The National Science Foundation discovered three minor problems, including one system glitch that prevented the processing of cash advances requested by grantees. The Energy Department's procurement data system temporarily rejected about 30 of 800 transactions, primarily because of a technical error by Energy employees. The Justice Department and the Federal Aviation Administration also encountered glitches in their financial management systems.

But the true test for agencies will not come until Jan. 1, when computers using two-digit dates need to correctly recognize "00" as 2000, not 1900. To handle potential computer bugs in January, most Cabinet departments and large agencies have devised what they call "Day One" strategies.

At the Social Security Administration, for example, an elaborate Day One plan emphasizes quickly catching any glitches that would stop or slow monthly benefit checks to 44 million Americans. The benefit payments--33 million of which are electronic transfers to banks--are among the most politically sensitive Y2K issues at the White House and in Congress.

Social Security programmers have sifted through 35 million lines of mainframe code and tested data exchanges with the Treasury Department, Federal Reserve and banks. When finished, the effort will have cost the agency an estimated $50 million.

Under Social Security's Day One plan, agency computers will shut down earlier than usual on Thursday, Dec. 30. Taking the systems off-line will allow officials to collect all their 1999 computer transactions from nearly 14,000 offices, including those in the distant time zones of Guam and Hawaii.

During that night, Social Security computers will finish batch runs where the data entered during the day is moved into master files. With its 1999 transactions completed and files updated, Social Security offices will be ready to close on Friday, Dec. 31 to observe the New Year's holiday.

Just before midnight Friday, Social Security's main data center in Baltimore will switch to generators powered by jet fuel. The agency has stockpiled sufficient jet fuel to to operate for several days. It does not expect any disruptions to the region's power grid, but as a precaution wants to guard against any electrical surges that could damage its automated equipment.

"We don't know if there [are] going to be power surges. We don't know, at this point, what the public is going to do. Is everybody going to get up and turn everything on to see if it's working? We have some concerns that we could have a lot of pull on electricity, so we don't want to take any chances," Kathy Adams, the Y2K expert at Social Security, said in an interview.

When the power company "lets [the agency] know everything is fine," Social Security will turn off its generators and hook back into regular power lines, Adams said. The power switching will not require the agency to turn off its computers.

On Saturday morning, New Year's Day, groups of programmers will report to work throughout the day to run checks on the computer systems. Social Security's 14,000 facilities include field offices, toll-free telephone call-in centers, appeals offices, regional offices and the Baltimore headquarters.

Social Security managers will report to their offices "at prearranged times with a checklist . . . and make sure the computers are working, that they can turn them on and get connections," Adams said. The managers will report their findings to regional offices, which will forward data to a command center in Baltimore, scheduled to open in late December.

Perhaps more important, Social Security has selected approximately 100 sites to serve as "barometer offices." At these facilities, which include 55 offices that make disability determinations, the agency's technical staff will test software systems by conducting a series of typical transactions, such as processing applications for benefits.

The Baltimore command center will monitor the processing and check to see that the systems are working properly. If glitches are found, "business resumption teams" will be dispatched to make any repairs. The teams will have Saturday night and Sunday to fix problems.

On Jan. 3, Social Security will open for business. If past years are a guide, that Monday will be one of the busiest days of the year. Many Americans choose to retire and apply for Social Security benefits on the first business day of the year, and Social Security hot lines take more calls in the first week than most other weeks of the year.

Social Security will also transmit benefits to about 44 million Americans that day, pumping $33 billion into the economy.

"The staff is focused and working hard," Adams said. "We're ready."