BOSTON (CBS) – Officers at Tufts Medical Center say that the hospital is operating smoothly even though the hospital stopped the nurses from returning Thursday morning at the end of their 24-hour strike.

At an afternoon press briefing, Tufts Cardiologist Dr. Andrew Weintraub says that the replacement nurses are professionals.

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“They performed superbly. The experience and expertise is evident the moment they stepped in. They performed in lock-step in taking care of these patients,” Weintraub said.

As for security issues, Tufts Director of Emergency Operations Rob Osgood says the biggest problem so far has been the noise.

“This is more particularly along that Washington Street corridor. Working with our city partners, especially the Boston Police, they’ve been extraordinarily helpful in helping us mitigate that noise,” Osgood said.

The replacement nurses are working on a 5-day contract, and Tufts says striking nurses can come back to work on Monday when that expires.

The hospital says that 13 nurses crossed the picket line Wednesday and were allowed to work Thursday. The hospital also reports that it’s business as usual, with 54 surgeries scheduled Thursday.

Many of the striking nurses continued to walk the picket line, holding signs and chanting “We want to work” and “Shame on you!” after the hospital didn’t allow the nurses to return to work.

About 1,200 nurses went on strike Wednesday at 7 a.m. as members of the Massachusetts Nurses Association (MNA) seek competitive wages, retirement benefits and better staffing.

They planned to return to the job Thursday at 7 a.m., but the hospital had already brought in more than 320 replacement nurses to fill the void.

Striking nurse and Co-Chair of the Massachusetts Nurse’s Association Bargaining Unit Barbara Tiller says she’s concerned about reports of unsafe conditions.

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“I’m really frustrated, we’ve heard about a lot of unsafe situations going on in there and they’re choosing to continue that,” Tiller said.

Tufts Medical Center spokesman Rhonda Mann says that the nurses knew before the strike that they would not be allowed to return to work Thursday.

“Part of the MNA playbook is staging a dramatic scene the morning after a strike. This is a stunt orchestrated for the media. The union was aware – well before it issued a strike notice – that a strike would force us to bring in expert nurses for a contractually-required five day period. We communicated this to our nurses through emails, meetings and letters sent to their homes. Nurses who came to work today may continue to work during the five day period. Those who chose not to work today know they can return Monday. If the MNA was so concerned about our nurses returning to the bedside, it should never have taken them out on strike and away from their patients.”

Nurses, however, disagree with the hospital’s position and claim they didn’t  receive proper notice about a lock-out.

“We haven’t gotten official notification of a 4-day lockout. So all of our peers are coming in for 7 a.m., hoping that cooler heads prevail and everyone get back to our patients and do what we love to do best – provide safe, skilled care,” striking nurse Denise Clements said.

However, the nurse’s union anticipated the lock-out as WBZ reported July 1.

The strike took place after last-minute negotiations between the hospital and union broke down.

Chief Nursing Officer Terry Hudson-Jinks said the hospital’s “best and final offer” added back $2.5 million to salaries and ensured that an additional number of nurses remained in the final proposal.

Hudson-Jinks said that pension remains the sticking point.

Tufts Medical Center Chief Nursing Officer Terry Hudson-Jinks. (WBZ-TV)

“Our philosophy has been simply stated. We respect decision our employees make. I respect the decision nurses made to walk out on their patients. I respect the decision some nurses made to work,” Hudson-Jinks said. “We’re going to respect everybody when they come back in and we’re going to welcome them back here. I have complete confidence we’re going to be able to do it.”

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WBZ NewsRadio 1030’s Ben Parker reports