Information Notice 2006-20, Foreign Material Found in the Emergency Core Cooling System
| ML062440467 | |
| Person / Time | |
|---|---|
| Issue date: | 10/16/2006 |
| From: | Ho Nieh NRC/NRR/ADRA/DPR |
| To: | |
| Carla P. Roquecruz, 301-415-1455 | |
| References | |
| IN-06-020 | |
| Download: ML062440467 (4) | |
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, DC 20555-0001
October 16, 2006
NRC INFORMATION NOTICE 2006-20:
FOREIGN MATERIAL FOUND IN THE
ADDRESSEES
All holders of operating licenses for nuclear power reactors, except those who have
permanently ceased operations and have certified that fuel has been permanently removed
from the reactor vessel.
PURPOSE
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to alert
addresses of the problem associated with foreign material in the emergency core cooling
system (ECCS) piping. This IN serves to reaffirm the importance of effective foreign material
exclusion (FME) controls. It is expected that addressees will review the information for
applicability to their facilities and consider actions, as appropriate, to avoid similar problems.
However, suggestions contained in this information notice are not NRC requirements; therefore, no specific action or written response is required.
DESCRIPTION OF CIRCUMSTANCES
On April 30 and May 1, 2006, with Oconee Unit 3 in Mode 5, the licensee conducted a foreign
object search and retrieval (FOSAR) of the A and B recirculation lines from the reactor building
emergency sump to the containment sump isolation valves prior to installing a new, larger
reactor building emergency sump (RBES) in support of resolution to Generic Safety
Issue (GSI) 191, Assessment of Debris Accumulation on PWR Sump Performance. These
lines provide the flowpath for the emergency sump recirculation for low pressure injection (LPI),
reactor building spray (RBS), and piggy back operation of high pressure injection (HPI).
The licensee discovered foreign material inside the LPI piping leading from the RBES to the 3B
LPI and RBS pumps. For this discovery in Oconee Unit 3, it was not possible to establish when
this debris was introduced to the sump lines.
Previously, on October 24 and 26, 2005, the licensee had discovered foreign material in
Oconee Unit 2 RBES piping while doing a FOSAR as part of GSI-191 post-modification
activities. (This discovery in Unit 2 is discussed in detail in Inspection Reports 05000269, 270,
287/2005005, and 2006002; ADAMS Accession Nos. ML060300467 and ML061180451 respectively).
As a result of the discovery of foreign material in the RBES recirculation piping in Oconee
Units 2 and 3, the licensee conducted a forced shutdown of Unit 1 to inspect the 1A and 1B
RBES recirculation piping. The licensee discovered foreign material inside the LPI piping
leading from the RBES to the 1B LPI and RBS pumps. (The discovery in Unit 1 and 3 is
discussed in detail in Inspection Report 05000269, 05000270, 05000287/2006003; ADAMS
Accession No. ML062090171).
DISCUSSION
The licensees investigation of foreign material found in the ECCS suction lines concluded that
the foreign material was the result of complacent FME awareness, training, and insufficient
procedural controls. During accident conditions, foreign material can be transported to
downstream ECCS components. This may impact the safety function of downstream ECCS
components during accident scenarios that require sump recirculation. The foreign material
could result in blockage and component damage.
The event described above illustrates the potential for adverse effects on the ECCS due to
foreign material and the importance of thorough inspections, FME controls when working on or
near ECCS, and consideration for inspections of some ECCS lines which may not have been
inspected for extended period.
Related Generic Communications
Generic Letter 2004-002, Potential Impact of Debris Blockage on Emergency Recirculation
during Design Basis Accidents at Pressurized-Water Reactors
Information Notice 96-10, Potential Blockage by Debris of Safety System Piping Which Is Not
Used During Normal Operation or Tested During Surveillances
Information Notice 94-57, Debris in Containment and the Residual Heat Removal System Information Notice 92-85, Potential Failures of Emergency Core Cooling Systems Caused by
Foreign Material Blockage
Information Notice 89-77, Debris in Containment Emergency Sumps and Incorrect Screen
Configurations
CONTACT
S
This information notice requires no specific action or written response. Please direct any
questions about this matter to the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
/RA/
Ho K. Nieh, Acting Director
Division of Policy and Rulemaking
Office of Nuclear Reactor Regulation
Technical Contacts: Carla P. Roquecruz, NRR
Steven M. Unikewicz, NRR
301-415-1455
301-415-3819 E-mail: cpr1@nrc.gov
E-mail: smu@nrc.gov
Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under the Electronic Reading Room/Document Collections. Information Notice 92-85, Potential Failures of Emergency Core Cooling Systems Caused by
Foreign Material Blockage
Information Notice 89-77, Debris in Containment Emergency Sumps and Incorrect Screen
Configurations
CONTACT
S
This information notice requires no specific action or written response. Please direct any
questions about this matter to the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
/RA/
Ho K. Nieh, Acting Director
Division of Policy and Rulemaking
Office of Nuclear Reactor Regulation
Technical Contacts: Carla P. Roquecruz, NRR
Steven M. Unikewicz, NRR
301-415-1455
301-415-3819 E-mail: cpr1@nrc.gov
E-mail: smu@nrc.gov
Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under the Electronic Reading Room/Document Collections.
Distribution:
IN Reading File
ADAMS Accession Number: ML062440467 OFFICE
IOEB:DIRS
CPTB:DCI
SSIB:DSS
BC:CPTB:DCI
TL:IOEB:DIRS
NAME
CPRoquecruz
SUnikewicz
MScott
TYLiu
ICJung
DATE
9/5/2006
9/5/2006
9/7/2006
9/8/2006
9/12/2006 OFFICE
ADRA:DPR
ADRA:DPR
BC:ADRA:DPR
D:DPR
NAME
CHawes CMH
DBeaulieu
CJackson
HNieh
DATE
09/14/2006
9/13/2006
9/14/2006
10/16/2006 OFFICIAL RECORD COPY