A FEASIBILITY STUDY FOR A SEISMIC EARLY WARNING SYSTEM FOR NUCLEAR POWER PLANT SHUTDOWN

A FEASIBILITY STUDY WILL BE CONDUCTED OF A SEISMIC SCRAM-PROCESSING SYSTEM IN WHICH P WAVES FROM LARGE EARTHQUAKES ARE DETECTED AND ANALYZED IN TIME TO INITIATE A NUCLEAR POWER PLANT CORE SHUTDOWN BEFORE THE ARRIVAL OF LARGE, DAMAGING SHEAR WAVE PHASES. A PROTOTYPE SEISMIC SCRAM-MONITORING SYSTEM WILL BE DESIGNED AND IMPLEMENTED ON A SUN 3/160 ENGINEERING WORKSTATION. IN THE PROPOSED SYSTEM, SEISMIC DATA WILL BE RECORDED BY SMALL SEISMIC ARRAYS (< 3-KM APERTURE) LOCATED NEAR THE EXPECTED SEISMOGENIC ZONES. PROCESSING STEPS WILL INCLUDE P PHASE DETECTION; ESTIMATION OF ARRIVAL TIME, AMPLITUDE, AND FREQUENCY; FREQUENCY WAVE NUMBER ANALYSIS TO DETERMINE APPARENT VELOCITY AND AZIMUTH; AND A SCRIPT-MATCHING PROCEDURE TO PREDICT THE AMPLITUDES OF LATER ARRIVING SHEAR PHASES. FREQUENCY WAVE-NUMBER (FK) MEASUREMENTS OF VELOCITYMAY BE USED TO IDENTIFY P PHASES. AZIMUTH AND FREQUENCY ESTIMATES WILL BE USED TO LOCATE THE SOURCE AND DISCRIMINATE BETWEEN EARTHQUAKES AND ARTIFICIAL SOURCES SUCH AS MINE BLASTS. IF THE EXPECTED GROUND MOTIONS FOR LATER-ARRIVING SHEAR PHASES EXCEED A THRESHOLD DEEMED UNSAFE, A SEISMIC SCRAM ALERT WILL BE GIVEN. THIS PROCESSING SCENARIO WILL BE TESTED USING REAL DATA FROM THE NORESS (NORWEGIAN REGIONAL SEISMIC SYSTEM) ARRAY IN NORWAY. SIMULATIONS WILL BE RUN TO DETERMINE IF SEISMIC SCRAM PROCESSING CAN BE ACCOMPLISHED BEFORE THE ARRIVAL OF LARGE DAMAGING SHEAR PHASES AT THE REACTOR SITE.