Information Notice 1995-34, Air Actuator and Supply Air Regulator Problems in Copes-Vulcan Pressurizer Power-Operated Relief Valves

Air Actuator and Supply Air Regulator Problems in Copes-Vulcan Pressurizer Power-Operated Relief Valves

ML031060298
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, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	08/25/1995
From:	Crutchfield D Office of Nuclear Reactor Regulation
To:
References
IN-95-034, NUDOCS 9508210169
Download: ML031060298 (8)

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UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 August 25, 1995 NRC INFORMATION NOTICE 95-34: AIR ACTUATOR AND SUPPLY AIR REGULATOR PROBLEMS

IN COPES-VULCAN PRESSURIZER POWER-OPERATED

RELIEF VALVES

Addressees

All holders of operating license or construction permits for nuclear power

reactors.

PurDose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information in

notice to alert addressees to problems caused by actuator degradation It is expected

Copes-Vulcan pressurizer power-operated relief valves (PORVs).

that recipients will review the information for applicability to their problems.

facilities and consider actions, as appropriate, to avoid similar constitute

However, suggestions contained in this information notice do not

NRC requirements; therefore, no specific action or written response is

required.

Description of Circumstances

During an inservice testing surveillance at the Haddam Neck nuclear power

plant on February 19, 1994, both pressurizer PORVs failed to open fully on

demand. At the time of the event, the plant was in cold shutdown and the

valves were not required to be operable. The cause was leaks in thecontrol air

actuator assemblies of both PORVs. Reduced pressure output of the air

regulators compounded the problem.

Discussion

The Haddam Neck PORYs are 2-inch nominal size, air-operated plug valves

manufactured by Copes-Vulcan (Model D-100-160). The portion of the control

air system that supplies air to the PORVs serves a safety-related function.

It is isolated from the remainder of the control air system by twoemergency safety- also includes a 405 liter (107-gallon] air

related check valves. It normal

accumulator to support PORV operation in the event of a loss of the PORVs (see

control air supply. Each of the air supply lines leading to the

Attachment 1) is equipped with a pressure regulator that reducespsig]. the air

pressure being supplied from 931 kPa [120 psig] to 690 kPa [85 An air

if

relief valve on each PORV actuator will protect it from overpressurization to open at

the supply line regulator fails open. These relief valves are set

793 kPa [100 psig], which is the maximum design pressure of the PORV

diaphragms.

9508210169 \ , /

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IN 95-34 August 25, 1995 The licensee determined that the primary cause of the unacceptable valve

stroke performance was air leakage from the PORV air actuators caused by

improper installation of the diaphragms. Both PORV diaphragms had been

replaced by a new style during a 1993 refueling outage. The principal

difference in the replacement diaphragms was a change in the material

composition. The replacement diaphragm was made of EPDM (Part #264331); the

old style diaphragm was made of BUNA-N (Part #080815). The licensee switched

to the EPDM diaphragms because of a vendor recommendation that EPDM would

provide enhanced performance under the temperature and radiation conditions

experienced by the PORV. In addition, the EPDM diaphragms have a 24-bolt-hole

configuration while the old style BUNA-N diaphragms only have a 12-bolt-hole

configuration. The diaphragms also have slightly different shapes.

The licensee apparently had some difficulty installing the EPDM diaphragms

because of the bolt hole pattern and shape differences between the EPDM and

BUNA-N style diaphragms. The licensee believes that the sealing surfaces of

the diaphragms were damaged as a consequence of the installation difficulties.

Extrusion of the diaphragm from between the base and cover and away from the

bolt holes led to small tears at several diaphragm bolt holes locations which

ultimately resulted in the air leakage. The licensee has chosen to use the

BUNA-N diaphragms to avoid the installation difficulties encountered with the

EPDM diaphragms. A Copes-Vulcan representative indicated that they have no

reports from other users on installation difficulties of either type of

diaphragm.

A search of the Nuclear Plant Reliability Data System (NPRDS) in regard to the

historical performance of the type of PORVs used at Haddam Neck revealed

numerous air-actuator related problems affecting this model of Copes-Vulcan

valves. The problems can be grouped into three categories:

(1) Actuator air leaks resulting from in-place diaphragm failures (e.g.,

holes, rips, and tears)

The plant-specific historical failure rates of these diaphragms should

be readily ascertainable from an empirical analysis of the maintenance

records. Recent failures of installed diaphragms may have implications

for the preventive maintenance or refurbishment program for these valves

at a particular licensee. Discussions with the Copes-Vulcan

representative indicate that replacement frequency depends on service

conditions such as temperature and valve usage. Diaphragm lifespan can

range from 1 year to more than 10 years.

Regarding the specific diaphragm failure which occurred at Haddam Neck, no data was available to support any correlation between diaphragm

failure and the type of diaphragm in use (EPDM versus BUNA-N).

s-' IN 95-34 August 25, 1995 (2) Actuator air leaks resulting from loose actuator cover bolts

Air leakage because of the loosening of air actuator cover bolts may

reflect the effect of environmental conditions on the valves.

Temperature variations can result in the thermal loosening of bolts.

Routine maintenance can also contribute to this problem if the cover

bolts are not tightened to manufacturer specifications whenever the

valve actuators are serviced.

(3) Valve stroke malfunctions resulting from improper supply of air pressure

from the air regulating valves

The air pressure regulators used at Haddam Neck are ITT Conoflow (Model

GFH25XT2365G) and have contributed to the PORV problems on three

separate occasions over the last several years. In 1993, one of the air

pressure regulators failed high, subjecting one of the PORY diaphragms

to the full air supply line pressure of 931 kPa [120 psig] which is

greater than the diaphragm design pressure of 793 kPa [100 psig].

Although the PORY actuators are equipped with relief valves to protect

the diaphragms from overpressurization, it is believed that the high

pressure contributed to or caused premature failure of the diaphragm.

In the other two instances, the air supply regulators had drifted low, resulting in inadequate stroke performance of the valves. The air

pressure regulator setpoints for the Haddam Neck configuration are 690

kPa [85 psig]. The PORVs need 552 kPa [65 psig] to start opening and

690 kPa [85 psig] to open fully. An engineering evaluation by the

licensee showed that the valves will come to the full open position with

control air pressure reduced to 586 kPa [70 psig] and reactor coolant

system pressure as low as 5895 kPa [840 psig].

Several causes of the air pressure regulator setpoint drift have been

postulated: one is that moisture intrusion from the control air system

can cause corrosion of the regulating mechanism, and the other is that

the drift may be configuration related. At Haddam Neck, the air

regulating valve is upstream of the (normally closed) solenoid operated

valve, meaning that the air regulating valve is constantly subjected to

system pressure: The air regulating valve vendor has indicated that

this configuration may cause setpoint drift.

Related Generic Communications

The issue of pressurizer PORY reliability has been addressed in Generic Letter 90-06, "Resolution of Generic Issue 70, 'Power-Operated Relief Valve and Block

Valve Reliability,' and Generic Issue 94, 'Additional Low-Temperature

Overpressure Protection for Light-Water Reactors,"' in which the staff

requested licensees to include the PORVs and PORV control air system in their

American Society of Mechanical EngineersSection XI inservice testing program.

/ V IN 95-34 August 25, 1995 written response. If

This information notice requires no specific action ornotice, please contact

you have any questions about the information in this of

one of the technical contacts listed below or the appropriate Office

Nuclear Reactor Regulation (NRR) project manager.

D 4e tchfeldDirctor

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: William C. Huffman, NRR Eric J. Benner, NRR

(301) 415-2766 (301) 415-1171 Charles G. Hammer, NRR

(301) 415-2791 Attachments:

1. PORV Actuation System

2. List of Recently Issued NRC Information Notices

PORV Actuation System

Alarm Set

@ 100 psig

Accumulator

120 psig 'I

Relief CA-V-834

Valve Similar for

PR-AOV-570

,A-RV-838A

,1 CA-SOV-754 CA-V-833A

From Containment

Pressure Reg. Control Air Compressors

Solenoid CA-PRV-836A (D CD \°

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F" in I

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PORV %D

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PR-AOV-568

<>Aachment 2 IN 95-34 August 25, 1995 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

Potential Loss of Spent 08/24/95 All holders of OLs or CPs

93-83, for nuclear power reactors.

Supp. 1 Fuel Pool Cooling After a

Loss-of-Coolant Accident

or a Loss of Offsite Power

Switchgear Fire and 08/23/95 All holders of OLs or CPs

95-33 for nuclear power reactors.

Partial Loss of Offsite

Power at Waterford

Generating Station, Unit 3 Potential for Loss of 08/11/95 All holders of OLs or CPs

95-10, for nuclear power reactors.

Supp. 2 Automatic Engineered

Safety Features Actuation

Thermo-Lag 330-1 Flame 08/10/95 All holders of OLs or CPs

95-32 for nuclear power reactors.

Spread Test Results

Motor-Operated Valve 08/09/95 All holders of OLs or CPs

95-31 for nuclear power reactors.

Failure Caused by Stem

Protector Pipe Inter- ference

Susceptibility of Low- 08/03/95 All holders of OLs or CPs

95-30 for nuclear power reactors.

Pressure Coolant Injection

and Core Spray Injection

Valves to Pressure Locking

Overspeed of Turbine- 06/16/95 All holders of OLs or CPs

94-66, for nuclear power reactors.

Supp. 1 Driven Pumps Caused by

Binding in Stems of

Governor Valves

Oversight of Design and 06/07/95 All holders of OLs or CPs

95-29 for nuclear power reactors.

Fabrication Activities

for Metal Components Used

in Spent Fuel Dry Storage

Systems

OL = Operating License

CP - Construction Permit

- ~IN 95-34 August 25, 1995 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 Office of

Nuclear Reactor Regulation (NRR) project manager.

orig /s/'d by DMCrutchfield

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: William C. Huffman, NRR Eric J. Benner, NRR

(301) 415-2766 (301) 415-1171 Charles G. Hammer, NRR

(301) 415-2791 Attachments:

1. PORV Actuation System

2. List of Recently Issued NRC Information Notices

DOCUMENT NAME: 95-34.IN

To caIva a

• nn y of this document. Indicate In the box: 'C' = CODv without attachmentienclosure 'E' = Copv with attachmentienclosure 'N' - No copy

OFFICE PECB/DRPM TECH ED E EMEB/DE BC:EMEB/DE ]

NAME EJBenner* MMejac* WHuffman* CHammer* RWessman* I

DATE 03/14/95 03/15/95 03/20/95 03/21/95 03/22/95 OFFICE SC:PECB/DRPM OECB/DRPM C:PECB/DRPM [Dt M INRRill

NAME EFGoodwin* RJKiessel* AEChaffee* DCF &f1-ed

DATE 08/03/95 07/28/95 08/03/95 08/4 95 _ __/

OFFICIAL RECORD COPY

"b - b-V'/

0

IN 95-xx

March xx, 1995 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 Office of

Nuclear Reactor Regulation project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: William C. Huffman, NRR Eric C. Benner, NRR

(301) 415-2766 (301) 415-1171 Charles G. Hammer, NRR

(301) 415-2791 Attachments:

1. PORV Actuation System

2. List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:\EJB1\COPES-VL.IN

To receive a copy of this document, Indicate Inthe box: 'C - Copy without attachment/enclosure 'E' - Copy with attachmentlenclosure

N' - No copy

i1, j BC:Hm

OFFICE

NAME

DATE

1 OECB/DOPS

EJBenner

03//1J/95 I 03//s-/95 TECH ED

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Id EMEB/DE

WHuffma

03A2o/95 EMEB/DE

03/Al/95 _3___95 an

OFFICE SC:OECB/DOPS CB/DOPS C:OECB/DOPS _DGPS/NRR

NAME lEFGoodwin RJKessel feeffltM _ O ehe5e AAEChaf

DATE 103/ /95 7 7/4¢95 co k l0i/3 /95 A03L /95 ROPPt

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