The Washington Hospital Center has more than quadrupled its security force in the face of a threatened strike by registered nurses called for this morning.

Hospital spokeswoman Jane Snyder said the additional 93 guards were hired to secure the 911-bed hospital's eight parking lots and almost 40 entrances.

The president of the nurses's union, however, expressed "shock and outrage" that "the Washington Hospital Center has seen fit to hire 93 additional guards. The Hospital Center's vicious attempt to intimidate and divide us should be protested by all responsible citizens," said nurse Dottie Hararas.

Snyder said the hospital's chief of security told the administration that he "could not handle the job with the staff he had."

"Everything is bigger here than everybody else's by about twice," she said, referring to the fact that the hospital Center is about double the size of any other private hospital in the metropolitan area.

Snyder said hospital officials were particularly concerned about the possibility of vandalism in the center's parking lots, and said that employees who would report to work in the event of a walkout had expressed concern about their cars.

Meanwhile, negotiations between the Hospital Center and the union representing its 425 registered nurses continued yesterday, following a Thursday session that lasted until after midnight. The two sides were reported to have made some progress, and the nurses presented a revised proposal to the hospital yesterday morning.

The two sides are not far apart on the question of salaries. But they still disagree on such questions as job schedules, vacation and sick leave, maternity leave, paid educational leave, the right of nurses to file grievances protesting performance ratings and the question of a closed union shop, which the nurses are demanding.

Nurses union officials predict that about 300 of the center's 425 nonsupervisory registered nurses would strike this morning if a settlement is not reached.

That would mean that 100 nursing supervisors and 125 other nurses would be on the job.

In preparation for possible walkout, the hospital has stopped elective admissions, discharged those patients it could and is taking only those urgent cases brought tothe center by ambulance.