Pepco Vote Gives River Terrace Hope

River Terrace residents said they were cautiously optimistic about approvals granted Monday for Potomac Electric Power Co. to build four new generators at its Chalk Point plant in Prince George's County. They said they hope it will mean the utility company will be less interested in expanding its Banning Road NE facility, although the company has not withdrawn its license request.

"People are very worried," said George Gurley, a River Terrace Advisory Neighborhood Commission member. He said residents want Pepco to withdraw its application because they feel the generators will damage the environment and their health.

The Maryland Public Service Commission Monday approved the expansion of the Chalk Point plant on the Patuxent River.

Pepco spokeswoman Nancy Moses said the utility will continue its pursuit of a license to expand the Benning Road plant in case something dramatic happens to require even greater energy production. Restricted Library Access

The west entrances on both levels of the Library of Congress's Thomas Jefferson Building at 10 First St. SE will close at 9:30 p.m. tomorrow and stay closed until late 1992 or early 1993 to permit restoration of the building's Great Hall.

For the next 18 or more months, access to the Jefferson Building will be restricted to the northeast rear door, and will be for research and official business only.

Visitors and first-time library users will be directed to the library's James Madison Memorial Building, across the street at 101 Independence Ave. SE. The Gutenberg Bible and the Giant Bible of Mainz exhibits will be moved from the great hall and be on view in the Madison Memorial Hall.

The social science reading room on the top floor of the John Adams Building at 110 Second St. SE will continue to serve as the primary reading room for researchers until the main reading room reopens. Marrow Donor Drive

The Prince Goerge's County family of Jocelyn Green has issued a plea to black people to step forward from 11 a.m. to 6 p.m. Sunday and get their blood tested on behalf of an ailing local 5-year-old. An all-day "Jazzathon for Jocelyn" featuring live entertainment will be held at Takoma Station tavern at 6914 Fourth St. NW to benefit the Help Jocelyn Fund.

Jocelyn Green's illness has been diagnosed as chronic myelogenous leukemia, a disease only a bone marrow transplant can cure. Without the transplant, doctors say, Jocelyn may live only another three years.

A family match is not available because she is adopted. Thus far, a search of 8,300 prospective donors has found no match.

A simple blood test can determine if an individual could be a possible donor. Each blood test costs $60, although prospective doners will only be asked to donate to that fee if they can.

For information, call Gwen Redding at 829-1999.