Except as otherwise provided in this chapter, the transfer pursuant to this subchapter of full-time personnel (except special Government employees) and part-time personnel holding permanent positions pursuant to this subchapter shall not cause any such employee to be separated or reduced in grade or compensation for one year after August 4, 1977, except that full-time temporary personnel employed at the Energy Research Centers of the Energy Research and Development Administration upon the establishment of the Department who are determined by the Department to be performing continuing functions may at the employee’s option be converted to permanent full-time status within one hundred and twenty days following their transfer to the Department. The employment levels of full-time permanent personnel authorized for the Department by other law or administrative action shall be increased by the number of employees who exercise the option to be so converted.