Information Notice 2001-14, Problems with Incorrectly-Installed Swing-Check Valves

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

ML012710212

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

Overexposures

______________________________________________________________________________________

OL = Operating License

CP = Construction Permit