It's a quiet Tuesday morning on punishment row, where misbehaving offenders at Stillwater Prison pull a little sack time before breakfast. But that changes in a minute when an inmate finishing an exercise break inside a wire cage refuses to "switch in" to his cell.

Seven corrections officers in white shirts -- the prison's quick response team -- charge into the cellhouse to confront the troublemaker. He decides he's not going to win and retreats to his cell.

This is life inside the segregation unit in Minnesota's largest prison, where 110 men on four tiers rattle and bang their way through the day, assaulting the senses with vulgarities and other rude remarks. They start fires, flood their sinks and toilets, pelt officers through the bars with spit, blood and human waste, attack with fists and knees. By afternoon the noise will rise to a deafening blend of shouts, name calling and political statements. This is a hell-on-earth place, a prison within a prison.

But today, the pandemonium will end. Offenders will be escorted out of the old unit in groups of four to the prison's spanking-new $19.6 million segregation building, a far safer place for the officers who manage them.

The old unit, built in 1914 and used for segregation since the 1970s, will be converted back to a regular cellhouse.

"We don't want it to be too comfortable," Warden John King said of the new unit where 150 new isolation cells with fresh clothing and clean floors await their occupants. "We don't want it to be draconian either, but we want them to correct their ways."

All of the offenders on the segregation unit broke prison rules to get there. Some tampered with security and defied rules of conduct. Others assaulted officers or other prisoners. They're an elite class of troublemakers in a 1,377-inmate prison that includes more than 500 men convicted of homicide and even more who committed aggravated assault and sex crimes.

Standing in the 1914 unit Tuesday was David Crist, a former warden at Stillwater and now assistant commissioner for facilities at the Minnesota Department of Corrections.

"It's very easy for people to get hurt if a struggle ensues up there," he said, pointing to narrow catwalks fronting rows of cells where some prisoners watched him through the bars. "If there's anything on the deck it gets really slippery."

For years, officers risked their safety when they had to navigate those catwalks to escort prisoners and deliver meals. Even chained, prisoners can't be securely restrained, and those locked in their cells often threw punches through the bars at passing officers.

The prison's Incident Command team -- the officers who respond to fights and other misbehavior -- was called to the old segregation unit 94 times from January through June. In addition to that, officers assigned to the unit handled possibly hundreds of lesser disciplinary cases by themselves.

Prison administrators hope that trend will change in the new unit, for which the Legislature appropriated money in 2006. Prisoners will be housed behind solid doors on wide, well-lit hallways. Four two-story wings are arranged like spokes, with the hub being a high-tech control room where officers have video surveillance. From that command post they can speak with inmates in their cells, lock and unlock doors, control water flows and even send sprays of chemical irritants into cells to subdue unruly behavior. Each of the wings will be segregated from the others because trouble can be contagious.

"Sometimes it's boredom, sometimes they're just mad about a decision that was made," said Lynn Dingle, who preceded King as warden. She now is the DOC's deputy commissioner for facilities and Crist's boss.

Prisoners have to earn their way back to Stillwater's main cellhouses -- and more privileges -- with good behavior. In some cases, they're awaiting legal action for assaults and other crimes they've committed in prison.

Segregation prisoners get no television or radio, but they'll be furnished 10 paperback books out of the prison library. For one hour, five days a week, each man will be allowed into an open room to exercise, take a shower and make phone calls. Their visiting privileges will be restricted to video conferences, reducing the danger of escorting them down long hallways.

All these modern security conveniences represent a huge change for corrections officers accustomed to insult-laden, ear-ringing shifts inside the 1914 segregation unit. But in the end, Crist said, the secret to keeping the peace in a prison lies in the hands of officers with good personal skills.

"What really makes the staff safe in here is not all the architecture, the handcuffs, the imminent force, it's the quality of their interaction with the offenders," he said.

Kevin Giles • 651-298-1554