ML12279A364

EDATS: Region I-2012-0309 - Response Letter to Maryland Senator Reilly Regarding Calvert Cliffs Dropped Control Rod

ML12279A364
Person / Time
Site:	Calvert Cliffs
Issue date:	10/04/2012
From:	Darrell Roberts Division Reactor Projects I
To:	Reilly E US SEN (Senate)
Dentel G
References
EDATS: RegionI-2012-0309
Download: ML12279A364 (3)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION REGION I 2100 RENAISSANCE BOULEVARD, SUITE 100 KING OF PRUSSIA, PENNSYLVANIA 19406-2713 October 4, 2012 The Honorable Edward R. Reilly The Senate of Maryland 11 Bladen Street, Room 321 Annapolis, MD 21401

Dear Mr. Reilly:

I am responding to your letter to Neil Sheehan of this office, dated September 20, 2012, expressing concerns regarding a control rod dropped into the core at the Calvert Cliffs Nuclear Power Plant on August 12, 2012.

On August 12, 2012, a single control rod dropped into the reactor core at Calvert Cliffs Unit 1, and the unit was subsequently shut down by plant operators. The safety function of the units 77 control rods is to drop into the reactor core to promptly stop the nuclear chain reaction when necessary. While the reactor is operating, a gripping system holds each control rod out of the core. In the event of a loss of power or failure of the gripping system, the control rods will drop into the core by gravity, fulfilling their safety function. The control rod drop that occurred on August 12, was caused by the failure of the portion of the gripping system that holds the individual control rod out of the core. Calvert Cliffs Unit 1 was shut down shortly after the control rod dropped to retrieve the rod and repair the gripping system on that rod.

The NRC reviewed this incident and determined that the failure of the portion of the gripping system, that held the dropped control rod, did not interfere with the ability of that rod to perform its safety function. When that portion of the gripping system failed, the control rod dropped into the core, as designed. While an inadvertent drop of a control rod into the core is undesirable, it does not represent a significant safety issue. In fact, Calvert Cliffs has procedures specifically detailing how to respond if a control rod drop occurs. NRC inspectors verified that Calvert Cliffs followed those procedures in response to the August 12 incident. Prior to restarting Unit 1, Calvert Cliffs replaced the gripping mechanism for the control rod that dropped. NRC inspectors reviewed the replacement plans and observed start-up activities. The NRC will review the long-term corrective actions that Calvert Cliffs develops and publish those results in a future inspection report that will be available at the following location:

http://www.nrc.gov/NRR/OVERSIGHT/ASSESS/CALV1/calv1_chart.html If you have additional questions related to this incident, please do not hesitate to contact Glenn Dentel of my staff at (610) 337-5233.

Sincerely,

/RA/

Darrell J. Roberts, Director Division of Reactor Projects

ML12279A364 Non-Sensitive Publicly Available SUNSI Review Sensitive Non-Publicly Available OFFICE RI/DRP RI/DRP RI/DRP NAME RBarkley/RSB GDentel/GTD DRoberts/DJR DATE 10/02/12 10/02/12 10/03/12 2

Distribution:

W. Dean, RA, Region I D. Lew, DRA, Region I D. Roberts, DRP D. Screnci, PAO N. Sheehan, PAO N. McNamara, ORA D. Tifft, ORA G. Dentel, DRP R. Barkley, DRP