Information Notice 2003-08, Potential Flooding Through Unsealed Concrete Floor Cracks
| ML031750847 | |
| Person / Time | |
|---|---|
| Issue date: | 06/25/2003 |
| From: | Beckner W NRC/NRR/DRIP/RORP |
| To: | |
| Replogle, George, RIV, 509-377-2627 | |
| References | |
| IN-03-008 | |
| Download: ML031750847 (5) | |
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555 June 25, 2003 NRC INFORMATION NOTICE 2003-08: POTENTIAL FLOODING THROUGH UNSEALED
CONCRETE FLOOR CRACKS
Addressees
All holders of operating licenses or construction permits for nuclear power reactors.
Purpose
The Nuclear Regulatory Commission (NRC) is issuing this information notice to inform
addressees of observed flooding in a room containing safety-related panels and equipment as
a result of fire water seepage through unsealed concrete floor cracks. It is expected that
recipients will review the information for applicability to their facilities and consider actions as
appropriate to avoid similar problems. However, suggestions contained in this NRC information
notice are not NRC requirements; therefore, no specific action or written response is required.
Description of Circumstances
On May 3, 2002, at Energy Northwests Columbia Generating Station, 15 to 20 gallons of water
spilled from a firewater drain line onto the floor of the radwaste building 484' elevation cable
spreading room. A small amount of this water leaked down into the remote shutdown room and
the Division II switchgear room, which is located below the cable spreading room floor. The
licensee determined that the pathway for the leakage was through cracks in the concrete floor.
Discussion
During the performance of a fire protection system surveillance test, 15 to 20 gallons of water
spilled on the cable spreading room floor. The water leaked through the concrete floor through
a small crack and a spalled area of the concrete floor. The rooms below the cable spreading
room floor housed the remote shutdown panel and safety-related switchgear. It was estimated
that only a small amount of the 15-20 gallons actually passed through the floor. No damage
occurred to the switchgear or the remote shutdown panel. However, thousands of similar small
cracks were present on the cable spreading room floor. The room also housed a deluge fire
system. Actuation or inadvertent rupture of the deluge system would likely result in additional
floor leaks that could impact the Division I and II switchgear, Division I and II batteries, the
remote shutdown panel and the alternate remote shutdown panel.
10 CFR 50, Appendix A, Criterion 3 requires licensees to design fire protection systems so that
their rupture or inadvertent operation does not significantly impair safety systems.
NRC Branch Technical Position 9.5.1, Appendix A, Guidelines for Fire Protection for Nuclear
Power Plants, references guidance contained in National Fire Protection Association (NFPA)
92M for maintaining concrete floors. NFPA 92M states that, Concrete floors should be
inspected frequently for cracks. Damaged floors may be repaired by use of special
compounds. Fine hairline cracks may, in most cases, be sealed with an application of floor
paint. As corrective measures, the licensee performed additional inspections and sealed all
appropriate unsealed concrete floors with an approved flexible epoxy coating.
The licensee determined that the cracks in the concrete floor resulted from flexing and
shrinkage of the floor. In the case of the spalled concrete around a penetration seal, the
material was degraded to the point that cracks provided a pathway for water to bypass the
penetration seal and enter the remote shutdown room. The degradation was caused by
cracking of the concrete during installation of the concrete anchors adjacent to the seal. The
cracking occurred due to insufficient distance between the concrete anchors which allowed the
formation of tensile shear cracks.
Neither the water that entered the remote shutdown room nor the water that entered the safety- related switchgear room caused safety-related equipment to become inoperable. In order for
the water entry to have become significant, the water would have had to collect in an area
where electrical contacts or terminals are located or enter into the cables. A related information
notice, IN 2002-12, Submerged Safety-Related Electrical Cables addresses cable failure
caused by water intrusion into the cable with subsequent drying and degradation of the
insulation.
This information notice requires no specific action or written response. If you have any
questions about the information notice in this notice, please contact the technical contact listed
below or the appropriate project manager from the NRCs Office of Nuclear Reactor Regulation.
/RA/
William D. Beckner, Program Director
Operating Reactor Improvements Program
Division of Regulatory Improvement Programs
Office of Nuclear Reactor Regulation
Technical contact: George Replogle, RIV
509-377-2627 E-mail: gdr@nrc.gov
Attachment: List of Recently Issued NRC Information Notices inspected frequently for cracks. Damaged floors may be repaired by use of special
compounds. Fine hairline cracks may, in most cases, be sealed with an application of floor
paint. As corrective measures, the licensee performed additional inspections and sealed all
appropriate unsealed concrete floors with an approved flexible epoxy coating.
The licensee determined that the cracks in the concrete floor resulted from flexing and
shrinkage of the floor. In the case of the spalled concrete around a penetration seal, the
material was degraded to the point that cracks provided a pathway for water to bypass the
penetration seal and enter the remote shutdown room. The degradation was caused by
cracking of the concrete during installation of the concrete anchors adjacent to the seal. The
cracking occurred due to insufficient distance between the concrete anchors which allowed the
formation of tensile shear cracks.
Neither the water that entered the remote shutdown room nor the water that entered the safety- related switchgear room caused safety-related equipment to become inoperable. In order for
the water entry to have become significant, the water would have had to collect in an area
where electrical contacts or terminals are located or enter into the cables. A related information
notice, IN 2002-12, Submerged Safety-Related Electrical Cables addresses cable failure
caused by water intrusion into the cable with subsequent drying and degradation of the
insulation.
This information notice requires no specific action or written response. If you have any
questions about the information notice in this notice, please contact the technical contact listed
below or the appropriate project manager from the NRCs Office of Nuclear Reactor Regulation.
/RA/
William D. Beckner, Program Director
Operating Reactor Improvements Program
Division of Regulatory Improvement Programs
Office of Nuclear Reactor Regulation
Technical contact: George Replogle, RIV
817-860-8147 E-mail: gdr@nrc.gov
Attachment: List of Recently Issued NRC Information Notices
DISTRIBUTION:
IN File
DOCUMENT NAME: C:\ORPCheckout\FileNET\ML031750847.wpd
Adams Accession No.:ML031750847 *See previous concurrence
OFFICE OES:RORP:DRIP Tech Editor* RIV (per email) RIV (per email)
NAME CDPetrone GDReplogle WBJones
DATE / /2003 06/09/2003 06/14/2003 06/14/2003 OFFICE RIV BC:SPLB:DSSA SC:RORP:DRIP PD:RORP:DRIP
NAME ATHowell JHannon TReis WDBeckner
DATE 06/23/2003 06/17/2003 06/24/2003 06/25/2003 OFFICIAL RECORD COPY
Attachment 1 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
_____________________________________________________________________________________
Information Date of
Notice No. Subject Issuance Issued to
_____________________________________________________________________________________
2003-07 Water in the Vent Header/vent 06/24/2003 All holders of operating licenses
Line Spherical Junctions for boiling water reactors (BWRs)
with a Mark I containment.
2003-06 Failure of Safety-related 06/19/2003 All holders of operating licenses
Linestarter Relays at San or construction permits for
Onofre Nuclear Generating nuclear power reactors, except
Station those that have permanently
ceased operations and have
certified that fuel has been
permanently removed from the
reactor.
2003-05 Failure to Detect Freespan 06/05/2003 All holders of operating licenses
Cracks in PWR Steam or construction permits for
Generator Tubes pressurized-water reactors
(PWRs).
2002-15, Sup 1 Potential Hydrogen 05/06/2003 All holders of operating licenses
Combustion Events in BWR for light water reactors, except
Piping those who have permanently
ceased operations and have
certified that fuel has been
permanently removed from the
reactor.
2002-21, Sup 1 Axial Outside-diameter 04/01/2003 All holders of operating licensees
Cracking Affecting Thermally for nuclear power reactors, Treated Alloy 600 Steam except those who have
Generator Tubing permanently ceased operations
and have certified that fuel has
been permanently removed from
the reactor vessel.
Note: NRC generic communications may be received in electronic format shortly after they are
issued by subscribing to the NRC listserver as follows:
To subscribe send an e-mail to <listproc@nrc.gov >, no subject, and the following
command in the message portion:
subscribe gc-nrr firstname lastname
______________________________________________________________________________________
OL = Operating License
CP = Construction Permit