Dynamic testing of pressure sensing lines in nuclear power plants

Commercial nuclear power plants are equipped with instrumentation designed to detect unsafe conditions and, if required, to initiate protective action. The time elapsed between the realization of an unsafe condition and the initiation of protective action is known as the response time of the instrumentation involved. The US Nuclear Regulatory Commission has issued guidelines that advise periodic in situ response-time testing of safety-related instrumentation. No method is currently available for in situ response-time testing of pressure sensing lines (fluid-filled tubes connecting process to pressure transducer). A proposed method of doing just that has been investigated. While the proposed test (the burp test) was found to be impractical, a theoretical description of the sensing line led to the realization that it is probably not necessary to test the response time of sensing lines. Experimental observations backed up this conclusion