Advanced Nuclear Power April2002



	Gaining new core operating margins provides many possible benefits: power gain, fuel cycle cost reduction and kWh cost reduction. Enhanced margins can be obtained by improving the core instrumentation associated with the system for monitoring the core operating limits. To increase or restore margins related to core operating limits, one approach is to improve the core instrumentation associated with the system for monitoring the limiting conditions of operations (LCO). The operating margin gains can then be used by the utilities for higher power, longer fuel cycles or enhanced flexibility. A combination of a fixed in-core instrumentation and an on-line three-dimensional neutronic calculation will be installed in September 2003 on the French 1300 MWe Cattenom Unit 1. Although developed for French plants and being tested in France, the system can benefit US plants as well. The purpose of the tests that will extend for one cycle plus the start of the following cycle, is to qualify the accuracy of the new margin evaluation system. A summary of the test results is expected in 2005 and the expected gain in power level is estimated to be as high as 8% on a French 1300 MWe reactor. An on-line 3D Core Monitoring System to Increase the Margins The on-line 3D Core Monitoring System uses proven technology and calculates the margins with respect to the core operating limits. This calculation is based on continuous knowledge of the three-dimensional power distribution in the core that is evaluated by combining measured information coming from neutron sensors at fixed locations in the core with theoretical information coming from a three-dimensional neutronic calculation carried out on-line. Framatome ANP is confident that the results of the Cattenom testing will verify that this new system really improves core margins. On-line Core Margins Monitoring System Architecture [click on image to enlarge] Anticipated Benefits Operating margin gain of a potential 8% can be used in one of several ways: Nuclear power can be increased by the same percentage Cycle lifetime increase can be converted into Equivalent Full Power Days (EFPD) to increase cycle length up to about 16 EFPD Flexibility can be increased Reduction of physical or periodic testing Replacement of moveable instrumentation

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