Improved conditions at the Prince George's County Detention Center have reduced, but not eliminated, the number of rapes and sexual assaults that occur in the jail, according to interviews with guards and inmates.

Rapes and sexual assaults are occurring at a rate of about four times a week at the jail in Upper Marlboro, according to guards and inmates, a decrease from previously published estimates of about a dozen times a week. (Jail director Arnett Gaston called those original estimates an exaggeration, saying the actual number was closer to four a month.)

The improved conditions include the installation of fluorescent lights outside some cellblock areas; installation of an intercom system between some cells and guard posts; more frequent patrols by guards of cellblock areas; the separation of inmates charged with violent crimes from those charged with nonviolent crimes, and the removal of blankets or trash bags that guards said prevented them from seeing inside cells.

The improvements were made after a series of articles in The Washington Post in September revealed that men were raping other men, violently and frequently, in the jail, which holds men and women awaiting trial or sentencing.

The articles, based on interviews with assailants, victims and jail personnel, reported that the rapes and sexual assaults occurred in cells beyond the vision of the guards; that jail rapists frequently put trash bags and blankets over the cells before the rapes; that inmates charged with violent crimes often raped inmates charged with nonviolent crimes, and that even when inmates screamed for help, the guards were unwilling--or unable--to respond.

After the articles were published, Gaston and then-county executive Lawrence J. Hogan promised to improve conditions at the jail to stop rapes, and a special grand jury was empaneled to investigate the incidents.

Gaston and jail spokesman Jim O'Neill have refused to speak to a reporter about changes at the jail or about alleged sexual assaults that have occurred since the articles were published. Gaston also ordered jail guards and employes not to talk to a reporter, citing the grand jury investigation. In addition, a longstanding departmental policy prohibits guards from talking to reporters.

Despite improvements at the jail, male inmates still sexually assault or rape other male inmates on a regular basis, according to guards and inmates. Two incidents during the past six weeks serve as examples:

On Nov. 27, James Anderson, a 25-year-old janitor from Pennsylvania who was in jail section 3B awaiting trial on a murder charge, said he was beaten by two men who stuck pencils into his rectum.

Anderson said the inmates began punching him and demanded that he give them oral sex. When he refused, one of the inmates grabbed him around the neck while the other grabbed him around the legs and the two undressed him and stuck pencils into his rectum.

The attack was confirmed by Dr. Dennis Frank of Prince George's General Hospital, who found "trauma" to Anderson's anus and abrasions in the back of his scalp, according to medical records.

Anderson told police the men who attacked him were Ronald Garnett, 24, of Northeast Washington, who is awaiting trial on a charge of assault with intent to murder, and Kirk Williams, 22, of Beltsville, who is serving a 10-year sentence for housebreaking. Anderson said a third man, Tony Majette, 22, of Southeast Washington, was a witness.

Anderson said he did not press his charges against them because he was afraid of retaliation. "That's suicide," he said.

During separate interviews with a reporter, Garnett and Williams denied assaulting Anderson; Williams said that he was not even in the cellblock at the time of the alleged attack. But Majette said that he saw Williams "body-punching" Anderson in the cell. Majette said, however, that Garnett was not in the cell at the time. There are no police or court records indicating that Garnett or Williams have been charged.

Four days after he was jailed last month, David Simms, 29, of Northwest Washington, said two men beat him and tried to rape him while he was asleep in jail section 3A.

According to an internal jail incident report, Simms suffered cuts and bruises on his face as a result of the beating.

The inmates Simms identified as his attackers, Eddie Morris Shackleford and Horacio Sails, said Simms suffered cuts and bruises on his face in a fight that occurred because Simms stole cigarettes from Shackleford. Shackleford, who was awaiting trial on an armed robbery charge on which he subsequently was acquitted, recalled that, "I told him, 'you going to pay me for my stuff or I'm going to take it out in a--.' "

After the beating, Simms said he ran from the cell to the guard post a few yards away, where, according to internal jail records, Theodore Durbin was on duty, sitting in a glass booth. Simms said he told Durbin that he wanted to speak to Durbin's superior. Simms then reported the incident and signed a statement that he wanted to press charges, according to internal jail records. But police were not called to investigate the incident, according to sources, and court records indicate that no charges were brought against the men.

Durbin declined to discuss the incident, citing the policy against speaking to reporters.

Simms, who also is known as Clarence Small, had been arrested by two security guards Nov. 6 for allegedly stealing 10 sweatsuits from the J.C. Penney store in Laurel. Simms then allegedly struck one of the security guards and stabbed the other one with a knife, according to court documents. Simms was charged with assault with intent to murder and was taken to the detention center in lieu of $75,000 bail.

While some reforms have been carried out at the jail, problems still exist:

* The jail remains overcrowded. During the past few weeks, according to internal jail records, the population of the old wing has been between 170 and 200 inmates, in a space designed for 100 inmates, and about 175 inmates are housed in a new wing, opened in 1977 to accommodate 75. After the newspaper series ran, Gaston said that the "fundamental problem" leading to sexual assaults was crowding in the jail. Since then, the overcrowding has been partially reduced with the purchase and installation of a 100-bed, prefabricated annex.

* There are a few additional guards assigned to each shift, but sources said there still are not enough to see what is happening in the cells that are not within view of the glass booths were most guards are stationed.

In September, on any one shift there were about 10 guards assigned to posts scattered throughout the detention center, plus one walking each of the five floors. Today, the same number remain at the posts, but the number walking patrol has increased, with one or two on each floor.

* Guards in the old wing do not walk into the cellblocks on a routine basis to check on inmates in the cells. Guards in the new wing enter the cellblocks every hour or so.

* Alleged sexual assaults are not always investigated or brought to the attention of the state's attorney's office. Simms' case is an example.

* Guards still read newspapers and magazines while they are supposed to be watching inmates, according to guards and inmates.