Basis for plant-specific low temperature overpressure protection system enable temperature

摘要

As older pressurized water reactors (PWRs) with high copper welds approach the end of their operating licenses and make the transition to a license renewal period, the Low Temperature Overpressure Protection (LTOP) System effective or enable temperature (T_emable) must take into account: centre dot increased RT_NDT values due to radiation induced embrittlement of reactor vessel material; centre dot temperature differences between the coolant and the 1/4 reactor vessel location; and centre dot additional margins imposed or regulatory requirements, such as instrument uncertainty.