Part 21 Report - 1998-330

LICENSEE: SIEMENS POWER CORP-NUCLEAR DIVISION SITE: SIEMENS POWER CORP-NUCLEAR DIV EN NUMBER:34119 DOCKET: EVENT DATE: 04-21-98 RX TYPE: EVENT TIME: 12:00 VENDORS: NOTIFY DATE: 04-22-98 EMERGENCY CLASS: N/A REGION: 4 STATE: WA TIME: 12:40 OPS OFFICER: DICK JOLLIFFE 10 CFR SECTION: CCCC 21.21 UNSPECIFIED PARAGRAPH 10 CFR PART 21 REPORT - NONCONSERVATIVE PREDICTION OF MONITORED CORE MCPR - SIEMENS POWER CORPORATION (SPC) PERSONNEL DETERMINED THAT ADDITIVE CONSTANTS USED IN THE MINIMUM CRITICAL POWER RATIO (MCPR) DETERMINATION FOR SIEMENS ATRIUM-9B FUEL BY THE CORE MONITORING SYSTEM WERE FOUND TO BE NON-CONSERVATIVE (UP TO 7.6% BASED ON THE ORIGINAL ADDITIVE CONSTANTS). IN ADDITION, SPC PERSONNEL DETERMINED THAT THE UNCERTAINLY IN THE ADDITIVE CONSTANT FOR THIS FUEL DESIGN WAS LARGER THAN PREVIOUSLY ESTIMATED. THE REVISED UNCERTAINTY HAS THE POTENTIAL TO AFFECT THE MCPR SAFETY LIMIT. SPC PERSONNEL NOTIFIED ALL SPC CUSTOMERS WITH ATRIUM-9B LEAD TEST ASSEMBLIES OR RELOAD QUANTITIES OF THE FUEL OF THE POSSIBLE NONCONSERVATIVE PREDICTION OF THE MONITORED MCPR AT CONDITIONS WHERE A SEVERELY UP-SKEWED AXIAL POWER SHAPE COULD OCCUR. PLANTS AFFECTED ARE DRESDEN UNIT 3 (CYCLE 15), QUAD CITIES UNIT 2 (CYCLE 15), AND KUOSHENG UNITS 1 AND 2.

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