Information Notice 1989-62, Malfunction of Borg-Warner Pressure Seal Bonnet Check Valves Caused by Vertical Misalignment of Disk

Malfunction of Borg-Warner Pressure Seal Bonnet Check Valves Caused by Vertical Misalignment of Disk
	ML031180730
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	08/31/1989
From:	Rossi C; Office of Nuclear Reactor Regulation
To:	;
References
	IN-89-062, NUDOCS 8908240375
	Download: ML031180730 (8)
	v • d • e

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 August 31, 1989 NRC INFORMATION NOTICE NO. 89-62: MALFUNCTION OF BORG-WARNER PRESSURE SEAL

BONNET CHECK VALVES CAUSED BY VERTICAL

MISALIGNMENT OF DISK

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

This information notice is intended to alert addressees of the potential mal- functioning of Borg-Warner pressure seal bonnet check valves caused by the

misalignment of the valve disk. 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 do not constitute NRC requirements; therefore, no specific action or written response is required.

Description of Circumstances

On April 23 and May 5, 1989, during hot functional testing at Comanche Peak

Unit 1, a combination of procedural errors and malfunctioning check valves

resulted in the backflow of high temperature water from the steam generators

through the auxiliary feedwater system to the condensate storage tank. This -

flow caused abnormally high temperatures, thermal stresses in excess of the

code allowable stresses, and damage to piping supports.

The procedural errors that occurred during testing on both dates involved simul- taneously opening both an auxiliary feedwater pump discharge valve connecting

the pump to the steam generators and an isolation valve in a test line leading

back to the condensate storage tank. During the time period covering both dates, each of the eight 4-inch Borg-Warner check valves in the auxiliary feedwater

supply lines leading to the steam generators :was Jammed partially open as a

result of improper assembly. This combination of circumstances allowed water

from the steam generators to flow back through the check valves, a pump dis- charge valve, and a test line isolation valve to the condensate storage tank.

In a separate incident on April 19, 1989, a 3-inch Borg-Warner check valve

located in the motor-driven auxiliary feedwater pump miniflow recirculation -

line was found to be inoperable. On examination, the two remaining 3-inch

miniflow recirculation valves in the auxiliary feedwater system also were

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8908240375 Z e Jya

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< IN 89-62 August 31, 1989 Investigation revealed that the valve disks of these three 3-inch valves, well as the eight inoperable 4-inch valves, were all positioned too low as

valve body relative to the valve seats. As a result, when the valve in the

disk moved

toward the seat, the outside upper edge of the disk was caught under the

upper edge of the seat causing the disk to be jammed open with the plane inside

disk at a large angle relative to the plane of the seat (Figure 1). of the

All

of the inoperable valves were of the 900 psi pressure seal bonnet type. eleven

Discussion:

During the two steam generator water backflow events, the operators

made almost

identical errors, although two different sets of valves were involved.

On

April 23 an auxiliary operator intended to realign valves associated

with the

turbine-driven auxiliary feedwater pump to permit recirculation flow

condensate storage tank. The procedure required closing the normally to the

turbine pump discharge valve (1AF-041) before opening the turbine pump open

lation test line isolation valve (1AF-042). However, the valves were recircu- simultaneously and the recirculation valve which could be opened rapidly,operated

fully open while the discharge valve which took a half hour to close, was

was still

open. In about 10 minutes the levels in steam generators 1, 2, and

noticed to be decreasing rapidly. At about 20 minutes into the event, 4 were

on the pipes in the turbine pump room was reported to be "bubbling and paint

peeling"

and the recirculation valve was closed, terminating the backflow.

On May 5 the operators were conducting an auxiliary feedwater system

ity test. The motor-driven auxiliary feedwater pump recirculation test operabil- isolation valve (1FA-055) was opened while the motor-driven pump discharge line

(lFA-054) was still open. Again, this was contrary to the procedure valve

which required closing the discharge valve prior to opening the test in use, isolation valve. During this event, only water from steam generator line

believed to have reached the auxiliary feedwater piping. The backflow1 is

initially stopped when the discharge valve (-054) was fully closed. was

However, when the operators attempted to restore the valves to the original position

to resume pumping to the steam generators, the test line isolation

was inadvertently left partially open, reestablishing the backflow valve

to

(-055)

densate storage tank. This backflow persisted for- the next hour and the con- being interrupted intermittently by the operation of the two auxiliary a half, water motor-driven pumps. The operators observing inconsistencies in feed- to the steam generators finally realized that the test line isolation the flow

valve

was open and closed it, terminating the backflow.

The reason that the disk assemblies of the malfunctioning check valves

positioned too low in the valve bodies was that an essential step was were

from the vendor's reassembly procedure. The disk assembly, as well missing

as

valve bonnet and seal, is suspended from and positioned vertically by the

a threaded

ring that is screwed into the top of the valve neck, called the retainer

ring

(Figure 1). The prescribed assembly procedure for the 3- and 4-inch valves

(Borg-Warner Operation and Maintenance Manual, OMM 1003) was to install

bottom out the retainer ring. This had the effect of locating the and

disk assembly

too low in the valve. The original factory assembly process included

the backing

IN 89-62 August 31, 1989 out of the retainer ring while observing the disk through the valve ports until

the disk had been raised to the correct height. However, the necessary step of

backing out the retainer ring to its original factory assembly height was not

included in the reassembly procedure provided with the 3- and 4-inch valves.

All of the auxiliary feedwater check valves had been disassembled and inspected

in 1983 because of a concern about the adequacy of the disk stud fillet welds.

During the following reassembly using the incorrect procedure, all of the 3- and

4-inch valve disks were positioned lower than the original factory adjusted

position. Larger Borg-Warner check valves (6, 8 and 10-inch) could also be

affected by this error.

The April 23 backflow of high temperature water caused a significant amount of

blistering and flaking of the paint on the auxiliary feedwater supply lines as

well as some unusual stressing of the auxiliary feedwater piping. However, the

May 5 backflow is believed to have caused the most damage. Several areas in the

piping are known to have experienced thermal stresses that exceeded the code

allowable stresses. In addition, one of the piping supports failed and had

to be replaced. As a result, an extensive analysis of the piping, the piping

supports, and the penetrations had to be made to ensure the continued reliabil- ity of the auxiliary feedwater system.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact one

of the technical contacts listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: H. H. Livermore, NRR

(817) 897-1500

M. F. Runyan, NRR

(817) 897-1500

Attachments:

1. Figure 1, Check Valve Shown with

Disk Jammed in Open Position

2. List of Recently Issued NRC Information Notices

Attachment 1 IN 89-62 August 31, 1989 RETAINER RING-

ADJUSTS HEIGHT OF

DISK ASSEMBLY

VALVE NECK

Figure 1. CHECK VALVE SHOWN WITH DISK

JAMMED IN OPEN POSITION

U4 v Attachment 2 IN 89-62 August 31,1989 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

89-61 Failure of Borg-Warner Gate 8/30/89 All holders of OLs

Valves to Close Against or CPs for nuclear

Differential Pressure power reactors.

88-48, Licensee Report of Defective 8/22/89 All holders of OLs

Supp. 2 Refurbished Valves or CPs for nuclear

power reactors.

89-60 Maintenance of Teletherapy 8/18/89 All NRC Medical

Units Teletherapy Licensees.

89-59 Suppliers of Potentially 8/16/89 All holders of OLs

Misrepresented Fasteners or CPs for nuclear

power reactors.

89-58 Disablement of Turbine-Driven 8/3/89 All holders of OLs

Auxiliary Feedwater Pump Due or CPs for PWRs.

to Closure of One of the

Parallel Steam Supply Valves

89-57 Unqualified Electrical 7/26/89 All holders of OLs

Splices in Vendor-Supplied or CPs for nuclear

Environmentally Qualified power reactors.

Equipment

89-56 Questionable Certification 7/20/89 All holders of OLs

of Material Supplied to the or CPs for nuclear

Defense Department by Nuclear power reactors.

Suppliers

89-45, Metalclad, Low-Voltage 7/6/89 All holders of OLs

Supp. 1 Power Circuit Breakers or CPs for nuclear

Refurbished With Substandard power reactors.

Parts

89-55 Degradation of Containment 6/30/89 All holders of OLs

Isolation Capability by a or CPs for nuclear

High-Energy Line Break power reactors.

89-54 Potential Overpressurization 6/23/89 All holders of OLs

of the Component Cooling or CPs for nuclear

Water System power reactors.

OL = Operating License

CP = Construction Permit

4, IN 89-62 August 31, 1989 out of the retainer ring while observing the disk through the valve ports until