Press Release-IV-15-028, - NRC to Begin Special Inspection at Callaway Nuclear Station

Press Release-IV-15-028 - NRC to Begin Special Inspection at Callaway Nuclear Station

ML15264A753
Person / Time
Site:	Callaway
Issue date:	09/21/2015
From:	Office of Public Affairs Region IV
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Category:Press Release
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Press Release-IV-15-028
Download: ML15264A753 (1)

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No: IV-15-028 September 21, 2015 CONTACT: Victor Dricks (817) 200-1128 Lara Uselding (817) 200-1519 NRC to Begin Special Inspection at Callaway Nuclear Station The Nuclear Regulatory Commission has begun a special inspection at the Callaway nuclear plant to review circumstances following a reactor shutdown involving the failure of three of four control valves that regulate water flow to the steam generators. The plant, operated by Ameren Missouri, is located near Fulton, Mo.

Following a reactor trip on Aug. 11, all systems performed as expected, including the automatic start of a system that controls water flow to the steam generators. However, when operators tried to switch to the motor-driven water pumps, a control valve failed to operate. Internal circuitry in the control valve system had been previously modified in late 2014, apparently introducing a flaw in the design that resulted in the failure.

The NRC learned that another control valve in the system had been similarly modified and also experienced a failure in December 2014. The affected valves were repaired and tested prior to the plant being restarted on Aug. 12. Additionally, the NRC is aware of a third unrelated control valve failure in the same system earlier this year that had already been corrected.

The purpose of this special inspection is to better understand the circumstances surrounding the valve failures, determine if the licensees extent of condition review was sufficiently comprehensive, and review the licensees corrective actions to ensure that the causes of the failures have been effectively addressed, NRC Region IV Administrator Marc Dapas said.

The NRC staff determined that a special inspection is warranted because the valves provide an important function in the mitigation of selected plant events. NRC inspectors will spend about a week on site looking into outstanding questions with respect to the licensees testing, maintenance, design change, and corrective action processes specific to these valves and the associated system. They will also evaluate the licensees root cause analysis and extent of condition review, and the adequacy of corrective actions.

An inspection report documenting the teams findings will be publicly available within 45 days of the end of the inspection.