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Category:NRC Preliminary Notification of Event/Occurrence
MONTHYEARPNO-III-18-002, Beaver Valley, Davis-Besse, Perry Notification of Bankruptcy Filing by Firstenergy Solutions2018-04-0404 April 2018
PNO-III-18-002: Beaver Valley, Davis-Besse, Perry Notification of Bankruptcy Filing by Firstenergy Solutions
PNO-III-16-004, A - Unplanned Shutdown of Davis-Besse Nuclear Power Station for Greater than 72 Hours - Update2016-09-23023 September 2016
PNO-III-16-004A - Unplanned Shutdown of Davis-Besse Nuclear Power Station for Greater than 72 Hours - Update
ML16257A2032016-09-13013 September 2016
PNO-III-16-004, Davis-Besse Nuclear Power Station, Unplanned Shutdown for Greater than 72 Hours
PNO-III-15-006, Davis-Besse Shutdown Due to Secondary Side Steam Line Rupture2015-05-13013 May 2015
PNO-III-15-006: Davis-Besse Shutdown Due to Secondary Side Steam Line Rupture
PNO-III-14-003, A - Update to Davis-Besse Shield Building Restoration2014-04-28028 April 2014
PNO-III-14-003A - Update to Davis-Besse Shield Building Restoration
ML14050A0262014-02-19019 February 2014
PNO-III-14-003: Davis-Besse Shield Building Voids
PNO-III-13-007, Davis-Besse Shield Building Laminar Cracks2013-09-20020 September 2013
PNO-III-13-007 Davis-Besse Shield Building Laminar Cracks
PNO-III-13-006, A: Davis Besse Preliminary Notification Update Unplanned Shutdown Greater than 72 Hours on June 29, 2013, Due to Trip of Reactor Coolant Pump and Subsequent Discovery of Reactor Pressure Boundary Leakage2013-07-15015 July 2013
PNO-III-13-006A: Davis Besse Preliminary Notification Update Unplanned Shutdown Greater than 72 Hours on June 29, 2013, Due to Trip of Reactor Coolant Pump and Subsequent Discovery of Reactor Pressure Boundary Leakage
ML13184A1762013-07-0202 July 2013
PNO-III-13-006 - Davis Besse Unplanned Shutdown Greater than 72 Hours on June 26, 2013, Due to Trip of Reactor Coolant Pump and Subsequent Discovery of Reactor Pressure Boundary Leakage
PNO-III-11-014, Davis-Besse Shield Building Indications2011-10-20020 October 2011
PNO-III-11-014, Davis-Besse Shield Building Indications
PNO-III-10-011, DAVIS-BESSE Start-Up of Following Repairs of Control Rod Drive Mechanism Nozzle Flaw Indications2010-06-29029 June 2010
PNO-III-10-011 - DAVIS-BESSE Start-Up of Following Repairs of Control Rod Drive Mechanism Nozzle Flaw Indications
PNO-III-10-008, Davis-Besse, Public Availability of Two NRC Employee Differing Professional Opinions Concerning Past Issues at Davis-Besse2010-05-20020 May 2010
PNO-III-10-008: Davis-Besse, Public Availability of Two NRC Employee Differing Professional Opinions Concerning Past Issues at Davis-Besse
PNO-III-10-003, A - Davis-Besse Nuclear Power Station - Update - Davis-Besse Control Rod Drive Mechanism Nozzle Indications2010-04-12012 April 2010
PNO-III-10-003A - Davis-Besse Nuclear Power Station - Update - Davis-Besse Control Rod Drive Mechanism Nozzle Indications
ML1007503172010-03-16016 March 2010
PNO-III-10-003 - Davis-Besse Nuclear Power Station - Davis-Besse Control Rod Drive Mechanism Nozzle Indications
PNO-III-09-005, A: Davis-Besse, Transitory Alert Due to Electric Device Failure (Update)2009-06-29029 June 2009
PNO-III-09-005A: Davis-Besse, Transitory Alert Due to Electric Device Failure (Update)
ML0917706352009-06-26026 June 2009
PNO-III-09-005: Davis-Besse, Transitory Alert Due to Electric Device Failure
PNO-III-06-002, Security Event at Davis-Besse2006-01-23023 January 2006
PNO-III-06-002-Security Event at Davis-Besse
PNO-III-04-008, Davis Besse Issued 08/04/2004 Re Automatic Reactor Shutdown2004-08-0404 August 2004
PNO-III-04-008: Davis Besse Issued 08/04/2004 Re Automatic Reactor Shutdown
PNO-III-04-003, Shutdown of the Davis-Besse Nuclear Power Station Plant for Greater than 72 Hours2004-03-17017 March 2004
PNO-III-04-003: Shutdown of the Davis-Besse Nuclear Power Station Plant for Greater than 72 Hours
PNO-III-03-010, Davis Besse: Fuel Loading2003-02-21021 February 2003
PNO-III-03-010, Davis Besse: Fuel Loading
PNO-III-02-036, Crack Identified in Vessel Head Stainless Steel Liner2002-09-10010 September 2002
PNO-III-02-036: Crack Identified in Vessel Head Stainless Steel Liner
ML0308703762002-09-10010 September 2002
Preliminary Notification of Event or Unusual Occurrence -- PNO-III-02-036
PNO-III-02-016, A; Discrete Radioactive Particles Found Outside the Radiologically Restricted Area, Davis-Besse Update2002-04-24024 April 2002
PNO-III-02-016A; Discrete Radioactive Particles Found Outside the Radiologically Restricted Area, Davis-Besse Update
PNO-III-02-006, B, Davis Besse - Reactor Vessel Head Degradation (Second Update)2002-04-0505 April 2002
PNO-III-02-006B, Davis Besse - Reactor Vessel Head Degradation (Second Update)
ML0235800962002-03-11011 March 2002
E-mail from PN1 to Events, Front, PN1, PN302006, Davis-Besse - Update - Significant Metal Loss Observed in Reactor Vessel Head
2018-04-04
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October 20, 2011 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-III-11-014 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region III staff on this date.
Facility Licensee Emergency Classification Davis-Besse Nuclear Power Station Notification of Unusual Event FirstEnergy Nuclear Operating Company Alert Oak Harbor, OH Site Area Emergency Docket: 50-346 General Emergency License: NPF-3 X Not Applicable
SUBJECT:
DAVIS-BESSE SHIELD BUILDING INDICATIONS DESCRIPTION:
On October 1, 2011, Davis-Besse shut down for a planned maintenance outage to replace the reactor vessel closure head. The reactor vessel closure head is bolted on top of the reactor vessel which is located inside a 1.5 inch thick steel containment vessel surrounded by a 2.5 foot thick free-standing, reinforced concrete, shield building. The majority of the shield building vertical exterior has additional non-structural, architectural concrete up to 1.5 foot thick separated by grooves. The containment vessel and shield building are separated by a 4.5 foot annulus/hollow space (see attachments). In order to remove the old reactor vessel closure head and install the new one, workers planned to create an opening in the reinforced concrete shield building and the steel containment vessel. The method used for the removal of concrete to create the temporary construction opening was hydro-demolition. Hydro-demolition is a method of concrete removal that utilizes high pressure water.
On October 10, 2011, during hydro-demolition operations, the licensee identified indications of potential fracture lines in various sections of the opening in the non-structural, architectural concrete of the shield building. The licensee is currently involved in activities to characterize these indications and determine what further actions need to be taken to address this issue.
Due to the annulus/hollow space that separates the reinforced shield building and the steel containment vessel, these indications do not affect the containment vessel. There are no indications present in the containment vessel.
The discovery of the indications in the concrete of the shield building does not represent an immediate safety concern because the plant is currently shutdown and the reactor vessel is defueled. If there are any challenges identified to the design function of the shield building they will have to be resolved before the plant restarts.
NRC inspectors were immediately notified of the indications of potential fracture lines in the concrete on October 10, 2011, and have been closely monitoring the plants actions and analysis. Currently, NRC inspectors are on-site reviewing and conducting their own independent inspection activities associated with the licensees replacement of the reactor vessel closure head. The identification of potential fracture lines in the shield building was not considered a reportable event according to the NRC regulations because there was no immediate safety concern identified and the reactor is shutdown.
This preliminary notification is issued for information only. State officials have been informed.
The information presented herein has been discussed with the licensee and is current as of October 19, 2011 at 4:30 p.m. (EDT).
ADAMS Accession Number: ML11293A092.
CONTACT:
David Hills, DRS 630/829-9733
Free-standing Steel Containment Vessel (1.5 inches)
Annulus/
Free-standing Hollow Reinforced Space Concrete Shield (4.5 feet)
Building (2.5 feet)
Note: This is a picture of the opening that was performed to replace the reactor vessel closure head in 2002, and is representative of what the current opening will eventually look like. The architectural concrete is not visible in this picture.
Annulus /
Hollow Free-standing Space Steel Containment Vessel Free-standing Reinforced Concrete Shield Building Simplified Davis-Besse Shield Building and Steel Containment Vessel Drawing
