Nurses at Crozer-Chester Medical Center were out on the pickets lines Monday for the second day of a planned two-day walkout to protest their lack of a new contract with the Delaware County hospital. The 565 Crozer-Chester registered nurses, represented by the Pennsylvania Association of Staff Nurses and Allied Professionals, have spent more than three months working under the terms of their previous contract, which expired June 8. Earlier this month, the nurses voted to hold a two-day strike—…