With lenders under pressure from the Obama administration and the Consumer Financial Protection Bureau to help prevent more graduate students and other private-student-loan borrowers from joining the 850,000 who are already in default, Citizens Bank, the UK-owned Rhode Island company that's one of Pennsylvania's largest lenders, says it's preparing to be one of the first banks to offer student-loan refinancing: variable-rate loans into fixed-rate loans, interest rates starting below 3%, no fees, and other perks.