Information Notice 2013-04, Concrete Subsurface Laminar Cracking Caused By Moisture Intrusion and Freezing

Concrete Subsurface Laminar Cracking Caused By Moisture Intrusion and Freezing

ML12352A052
Person / Time
Issue date:	03/07/2013
Revision:	0
From:	Dudes L A, Kokajko L E Division of Policy and Rulemaking, Division of Construction Inspection and Operational Programs
To:
Klos L J, NRR/DPR, 415-5136
References
IN-13-004
Download: ML12352A052 (7)

March 7, 2013

NRC INFORMATION NOTICE 2013-04: SHIELD BUILDING CONCRETE SUBSURFACE LAMINAR CRACKING CAUSED BY MOISTURE INTRUSION AND FREEZING

ADDRESSEES

All holders of an operating license or construction permit for a nuclear power reactor under Title 10 of the Code of Federal Regulations (10 CFR) Part 50, "Domestic Licensing of Production and Utilization Facilities," except those who have permanently ceased operations and have certified that fuel has been permanently removed from the reactor vesse All holders of an operating license for a non-power reactor (research, test reactor, or critical assembly) under 10 CFR Part 50, "Domestic Licensing of Production and Utilization Facilities," except those who have permanently ceased operations. All holders of and applicants for a power reactor early site permit, combined license, standard design certification, standard design approval, or manufacturing license under 10 CFR Part 52, "Licenses, Certifications, and Approvals for Nuclear Power Plants."

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform addressees of the occurrence of laminar subsurface cracks in the reinforced concrete shield building (SB) of the containment system at the Davis-Besse Nuclear Power Station caused by moisture intrusion and freezin The NRC expects that recipients will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problem However, suggestions contained in this IN are not NRC requirements; therefore, no specific action or written response is required. DESCRIPTION OF CIRCUMSTANCES On October, 10 2011, the shield building (SB) of Davis-Besse's containment was cut open to permit removal of the old reactor vessel head and installation of the replacement vessel hea At that time, the licensee discovered subsurface cracking located near the outer rebar mat, which extended to adjacent areas of the SB that have not been modified since original constructio A manual chipping process was applied to the cracked area in an initial attempt to determine the extent of the crack Using this method, crack indications along the vertical edge of the containment access opening essentially disappeared, but a crack at the top horizontal cut for the opening did not disappea The licensee investigated and confirmed, through the use of impulse response (IR) mapping and core boring samples (CBS), that subsurface laminar cracking had occurred along the outer rebar mat in the SB flute shoulder areas and at the top of the SB near the junction with the ML12352A052 IN 2013-04