Information Notice 2001-14, Problems with Incorrectly-Installed Swing-Check Valves
| ML012710212 | |
| Person / Time | |
|---|---|
| Issue date: | 10/03/2001 |
| From: | Imbro E Operational Experience and Non-Power Reactors Branch |
| To: | |
| vsb | |
| References | |
| TAC MA2314 IN-01-014 | |
| Download: ML012710212 (6) | |
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001 October 3, 2001 NRC INFORMATION NOTICE NO. 2001-14: PROBLEMS WITH INCORRECTLY-INSTALLED
SWING-CHECK VALVES
Addressees
All holders of operating licenses for nuclear power reactors, except those who have 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 to alert
addressees to swing-check valve problems caused by incorrect installation. 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 information
notice are not NRC requirements; therefore, no specific action or written response is required.
Description of Circumstances
Cooper Nuclear Station
While trouble-shooting a leaking check valve between the reactor core isolation cooling
barometric condenser and the suppression pool, the licensee determined that a check valve
had been installed rotated 90 degrees away from the orientation recommended by the valve
vendor. According to the vendors technical manual, the valve should have been installed either
in a horizontal line with the hinge pin centerline vertical or in a vertical line with flow upward.
The staff documents this problem with certain Anderson-Greenwood check valves in Inspection
Report 50-298/98-05 (NUDOCS Accession Number 9809240061).1*
The check valves of concern are designed so that, when installed in a horizontal run of piping, the axis of the hinge is vertical and the check valve disc pivots in the horizontal plane, like a
door. The licensee incorrectly installed the valves with the hinge pin horizontal, so the disc did
not pivot in the horizontal plane as required. The disc face pivoted from a horizontal plane, on
forward flow, to a vertical plane on flow reversal. Therefore, the disc tended to hang open on
reversal and cessation of flow. This effect can be visualized from attached Figure 1, which
shows the relationship of the center of gravity of the disc to the axis of the hinge pin. The
spring shown wound around the hinge pin is intended to close the valve against only the design
frictional and drag forces expected to exist with the hinge pin vertical or with the valve in a
1
- NUDOCS documents can be accessed at the NRC Public Document Rooms vertical run of pipe; it was not designed to overcome the gravitational force that would tend to
hold the valve open when the hinge pin axis is horizontal and the valve is in a horizontal run of
pipe.
As part of its actions to correct this problem, the licensee identified several other check valves
of this type installed with this incorrect orientation.
Palo Verde Nuclear Station
The licensee experienced excessive leakage through some Borg-Warner swing-check valves in
the high-pressure safety injection (HPSI) system. The root cause of the problem was
determined to be an error in valve assembly during the original installation. As a result, the disc
assembly was suspended too low inside the body of the valve. With the disc assembly
suspended too low, the valve might have seated acceptably at first but remained partially open
after forward flow exercised the valve.
The improper assembly occurred during plant construction. The licensee removed the internals
of these valves so the valve bodies could be welded into the piping. During reassembly of the
internals, the bonnet retaining ring was threaded into the body until it bottomed. The original
factory assembly process included a step that involved backing out the bonnet retaining ring, after it bottomed in the valve body, until the correct disc height was obtained, as visually
observed through the open ends of the valve body. At Palo Verde, however, the valve had
been installed in the piping and the valve internals could not be observed. Therefore, the disc
height adjustment could not be made during valve reassembly, and the disc remained too low in
the body to engage the seat properly.
The NRC staff had addressed this problem in Information Notice IN 89-62, Malfunction of
Borg-Warner Pressure Seal Bonnet Check Valves Caused by Vertical Misalignment of Disk, dated August 31, 1989 (NUDOCS Accession Number 8908240375). After IN 89-62 was
issued, the valve vendor issued maintenance guidance to recommend that measurements of an
internal critical dimension be done to ensure that the disc is in the correct position following
maintenance.
Until November 1994, the licensees maintenance procedure for these check valves did not
include adequate instructions for ensuring correct vertical positioning of the disc. Once the
problem was diagnosed in 1998, the licensee implemented a plan to identify and correct the
error on all of the HPSI discharge check valves. The NRC staff described the licensees
actions on this problem in Inspection Report 50-528/529/530 98-14 (NUDOCS Accession
Number 9809090298).
Discussion
As a result of the installation and maintenance errors discussed in this information notice, some
check valves did not seat properly. Furthermore, the problems at Cooper and Palo Verde
reveal the importance of timely incorporation of vendor recommendations into work instructions
to ensure that check valves are installed and maintained properly. Specifically, the problems highlight the need to install Anderson Greenwood check valves in accordance with vendor
guidance and to ensure that the Borg-Warner check valve disc is in its correct vertical position.
This information notice requires no specific action or written response. However, recipients are
reminded that they are required to consider industry-wide operating experience (including NRC
information notices), where practical, when setting goals and performing periodic evaluations
under 10 CFR 50.65, Requirement for Monitoring the Effectiveness of Maintenance at Nuclear
Power Plants. If you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of Nuclear Reactor
Regulation (NRR) project manager.
/RA Patrick M. Madden Acting for/
Eugene V. Imbro, Acting Chief
Operational Experience
and Non-Power Reactors Branch
Division of Regulatory Improvement Programs
Office of Nuclear Reactor Regulation
Technical Contacts: Charles Marschall, Region IV Robert Benedict, NRR
(817) 860-8185 (301) 415-1157 E-mail: csm@nrc.gov E-mail: rab1@nrc.gov
Attachments:
1. Figure 1. Anderson Greenwood Check Valve
2. Figure 2. Borg-Warner Check Valve With Disk Jammed in Open Position
3. List of Recently Issued NRC Information Notices
ML012710212 TEMPLATE NO.=NRR-052
- See previous concurrence
OFFICE REXB Tech Editor RIV C:EMEB REXB AC:REXB
NAME RBenedict* PKleene* CMarschall PKuo* JTappert EVImbro
DATE 09/06/2001 09/ 04 /2001 / /2001 09/26/2001 / /2001 / /2001
Attachment 1
Attachment 2 Attachment 3 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
_____________________________________________________________________________________
Information Date of
Notice No. Subject Issuance Issued to
______________________________________________________________________________________
2001-13 Inadequate Standby Liquid 10/03/01 All holders of operating licenses
Control System Relief Valve for boiling water reactors
Margin
2001-12 Hydrogen Fire at Nuclear 8/08/01 All holders of operating licenses
(ERRATA) Power Stations or construction permits for
nuclear power reactors except
those who have ceased
operations and have certified that
fuel has been permanently
removed from the reactor vessel
2001-12 Hydrogen Fire at Nuclear 7/13/01 All holders of operating licenses
Power Stations or construction permits for
nuclear power reactors except
those who have ceased
operations and have certified that
fuel has been permanently
removed from the reactor vessel
2001-11 Thefts of Portable Gauges 07/13/01 All portable gauge licensees
2001-10 Failure of Central Sprinkler 06/28/01 All holders of licenses for nuclear
Company Model GB Series power, research, and test
Fire Sprinkler Heads reactors and fuel cycle facilities
2001-09 Main Feedwater System 06/12/01 All holders of operating licenses
Degradation in Safety-Related for pressurized water nuclear
ASME Code Class 2 Piping power reactors, except those who
Inside the Containment of a have permanently ceased
Pressurized Water Reactor operations and have certified that
fuel has been permanently
removed from the reactor vessel
2001-08 Update on the Investigation of 06/06/01 All Medical Licensees
Supplement 1 Patient Deaths in Panama, Following Radiation Therapy
______________________________________________________________________________________
OL = Operating License
CP = Construction Permit