Abstract
During reload startup of a nuclear power plant (NPP), physics tests are performed to verify the consistency of core neutronic characteristics with design expectations. Physics tests time during power ascension directly affects the power rise rate and economy of units operation. The paper studied the physics tests process during power ascension of reload startup in Sanmen NPP, and proposed an optimization scheme for Sanmen reload startup physics tests based on test data analysis and simulation. On the premise of meeting the requirements of current guidelines and standards, the scheme optimizes the current test method from the aspects of test contents andtest initial conditions, which can effectively reduce risk to core operation, shorten test time and improve economy of units operation. In terms of test content, it was demonstrated that the influence of detector leakage current on the power distribution measurement can be ignored, which can reduce the times of leakage current measurement in the process of power rise. In terms of the test initial conditions, the influence of xenon on the test process and results was analyzed, so as to relax the initial conditions of xenon equilibrium and shorten the total power rise time from about 4 days to about 2 days. Standard compliance was also evaluated, and the optimizations are in accordance with the requirements in current standards.
