Information Notice 1992-60, Valve Stem Failure Caused by Embrittlement

Valve Stem Failure Caused by Embrittlement

ML031200041
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:	08/20/1992
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-92-060, NUDOCS 9208140032
Download: ML031200041 (8)

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UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 August 20, 1992 NRC INFORMATION NOTICE 92-60: VALVE STEM FAILURE CAUSED BY EMBRITTLEMENT

Addressees

All holders of operating licenses or construction permits for pressurized

water reactors (PWRs).

Purpose

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

notice to alert addressees to problems in which valve stems manufactured from

American Society of Mechanical Engineers (ASME) SA 564, Type 630, H900 through

H1150 age treatment condition (17-4 PH) stainless steel could become brittle

and fail if used in environments that exceed 600 'F. It is expected that

recipients will review this 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.

Backqround

Power-operated relief valves (PORVs) connected to the pressurizer are designed

for the valve stems to operate at saturated steam temperatures. The valve

stem thermal history is affected by thermal conduction through the valve disk

and by direct contact to the fluid discharge as a result of valve actuation.

The normal operating saturation temperature in a PWR is approximately 650 'F.

The maximum design temperatures are higher.

Data obtained by the Duke Power Company from testing on 17-4 PH material in

the age treated condition indicate that this material will, after several

thousand hours at 600 'F, exhibit an increase in tensile strength with an

accompanying large decrease in ductility (secondary aging). The secondary

aging mechanisms are the continued precipitation of the intermetallic

compounds and the precipitation of chromium in ferrite (885 'F embrittlement).

After secondary aging occurs, the material with low ductility will have an

increased susceptibility for fracture, especially when subjected to high

torque from a power actuator.

Description of Circumstances

On December 9, 1991, the Catawba Nuclear Station, Unit 2, was in Mode 5 (hot

shutdown) in the final stages of a refueling outage. The pressure in the

reactor coolant system was approximately 177 psig.

f9208140032) Z _

42\ A

III

IN 92-60

--/August 20, 1992 Operations personnel had noted some unexpected

pressurizer relief tank earlier during perturbations in the

the normal reactor coolant system fill- and-vent process which led them to suspect

2NC-32B or its associated block valve 2NC-31B that either pressurizer PORV

Both valves appeared to stroke when observed may not be opening properly.

valves were functioning properly, operations locally. To verify that the

depressurize the reactor coolant system personnel attempted to

room. When the PORV was opened, and the by opening the PORV from the control

block valve 2NC-31B indicated an open

condition, the reactor coolant system pressure

personnel suspected that the PORV block remained stable. Operations

position. valve was stuck in the closed

The PORV block valve is a motor operated

Edward Valve Company) Equiwedge gate valve. 3-inch Rockwell International (now

on a test performed on the block valve The licensee reviewed the data

suggested that the stem of the valve had actuator on November 25, 1991, which

because the stem pullout force was much separated from the gate assembly

replaced the PORV block valve and verified lower than normal. The licensee

failure occurred in an area where the valve that the stem had failed. The

assembly. The licensee replaced the valve stem attached to the gate

radiographically tested the other PORV with a different type of valve, and

that they were intact and open. block valves on both units to verify

Discussion

____The licensee performed_a metallurgical

analysis of the fractured stem and

found that the material had lost ductility

Apparently, the stem end attached to the at the point of fracture.

disk

temperatures above 600 OF for several thousand was exposed to pressurizer

by the power operator was sufficient to hours. The high torque applied

shear the stem.

The Edward Valve Company indicated that

ASME SA 564, Type 630 (17-4 PH, with an valve stems made of this material, embrittled in as little as 5,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> aging treatment of H1100), can become

when exposed to temperatures greater

than 600 'F. Preliminary information indicates

used in the stems of PORVs and PORV block that this material is widely

valves.

It is important to note that a valve with

surveillance test. For example, if the a severed stem may pass a

safety

close, and the valve is tested in the closed function of the valve is to

force can be obtained even with a severed direction, an acceptable closing

with the 2NC-31B valve. Determining the stem. This was, in fact, the case

concern for those systems with valves thatvalve disk position is an operability

operations but are closed during accident are normally opened during

conditions.

II

K... IN 92-60

August 20, 19921 I 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 project manager

in the Office of Nuclear Reactor Regulation (NRR).

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contacts: William Orders

(803) 831-2963 Donald Naujock

(301) 504-2767 Attachment: List of Recently Issued NRC Information Notices

Attachment

IN 92-60

August 20, 1992 Page I of 1 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

92-59 Horizontally-Installed 08/18/92 All holders of OLs or CPs

Motor-Operated Gate for nuclear power reactors.

Valves

92-58 Uranium Hexafluoride 08/12/92 All Fuel Cycle Licensees.

Cylinders - Deviations

in Coupling Welds

92-57 Radial Cracking of 08/11/92 All holders of OLs or CPs

Shroud Support Access for boiling water reactors

Hole Cover Welds (BWRs).

92-56 Counterfeit Valves in 08/06/92 All holders of OLs or CPs

the Commercial Grade for nuclear power reactors.

Supply System

92-55 Current Fire Endurance 07/27/92 All holders of OLs or CPs

Test Results for for nuclear power reactors.

Thermo-Lag Fire Barrier

Material

92-54 Level Instrumentation 07/24/92 All holders of OLs or CPs

Inaccuracies Caused by for nuclear power reactors.

Rapid Depressurization

92-53 Potential Failure of 07/29/92 All holders of OLs or CPs

Emergency Diesel Gen- for nuclear power reactors.

erators due to Ex- cessive Rate of Loading

91-52, Nonconservative Errors 07/16/92 All holders of OLs or CPs

Supp. I in Overtemperature Delta- for Westinghouse (W)-

Temperature (OTAT) Set- designed nuclear power

point Caused by Improper reactors.

Gain Settings

92-52 Barriers and Seals 07/15/92 All holders of OLs or CPs

Between Mild and for nuclear power reactors.

Harsh Environments

OL - Operating License

CP - Construction Permit

3/4 This informa ion notice requires no specific action or written respon If

you have any uestions about the information in this notice, please ontact

one of the tec nical contacts listed below or the appropriate pro .ct manager

in the Office o Nuclear Reactor Regulation (NRR).

Charles E. Rossi, Director

Division of Operational Ey nts Assessment

Office of Nuclear React Regulation

Technical contacts: William Orders

803) 831-2963 Do ald Naujock

(30 ) 504-2767 Attachment: List of Recentl Issued NRC nformation Notices

\

DISTRIBUTION:

Central Files RAHermar

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7/3 /92 7/i3/ 9 2 I / 7 /13/92 / /92 / /92 / /92 OFFICIAL RECORD COPY P FILENAME: g:\ED WARDS

IN 92-60

August 20, 1992 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 project manager

in the Office of Nuclear Reactor Regulation (NRR).

Original Signfd by

Charles E. Roti

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contacts: William Orders

(803) 831-2963 Donald Naujock

(301) 504-2767 Attachment: List of Recently Issued NRC Information Notices

Document Name: 92-60.IN

• See previous concurrence

• OGCB:DOEA:NRR *C/OGCB:DOEA:NRR

AJKugler GHMarcus

08/03/92 08/05/92 O8//~49

• EMCB:DET:NRR *EMCB:DET:NRR *AC/EMCB:DET:NRR *RPB:ADM *D/DET:NRR

DGNaujock RAHermann WBateman JMain JERichardson

07/13/92 07/13/92 07/17/92 07/13/92 07/21/92

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IN 92-XX

August XX, 1992 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 project manager

in the Office of Nuclear Reactor Regulation (NRR).

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contacts: William Orders

(803) 831-2963 Donald Naujock

(301) 504-2767 Attachment: List of Recently Issued NRC Information Notices

• See previous concurrence

OGCB:DOEA:NRR C/OG KRR i D/DOEA:NOD

AJKugler g K CHBerl ger CERossi '

08/ 3 /92 08/3/92 08/ /92

• EMCB:DET:NRR *EMCB:DET:NRR *AC/EMCB:DET:NRR *RPB:ADM *D/DET:NRR

DGNaujock RAHermann WBateman JMain JERichardson

07/13/92 07/13/92 07/17/92 07/13/92 07/21/92

-3 -

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 project manager

in the Office of Nuclear Reactor Regulation (NRR).

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contacts: William Orders

(803) 831-2963 Donald Naujock

(301) 504-2767 Attachment: List of Recently Issued NRC Information Notices

DISTRIBUTION:

Central Files RAHermann

DET RF CBerlinger

EMCB RF CRossi

DGNaujock

WFOrders

• See previous concurrence

• DET:EMCB *DET:EMCB *AC:EMCB *TechEd

DGNaujock:dn RAHermann WBateman JMain

07/13/92 07/13/J9t, 07/17/92 07/13/92 DOEA: D

CRossi

/ /92 OFFICIAL RECORD COPY WP FILENAME: g:\EDWARDS

- I -

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- 1 -

This information notice requires no specific action or writter/

response. If you have any questions about the information iy

this notice, please contact one of the technical contacts Tasted

below the appropriate project manager in the Office of uclear

Reactor egulation (NRR).

Charles E. Rossi, Director

Division of Operational Even s Assessment

Office of Nuclear Reactor gulation

Technical contact\: William Orders

(803) 831-2963 onald Naujock

( 1 504-2767 Attachment: List of Rece .d NRC Information Notices

DISTRIBUTION:

Central Files RAHerman

DET RF CBerling

EMCB

uv\au:RF_O_. CRossi

DuNau] ock/

WFOrders

• See Previous Concurren s

• DET:EMCB *DET: B AC:EMC / 2 I *TECHEM

DGNaujock:dn RAHer ann WBatema WV JMain

07/13/92 07/1 /92 07/17/9 07/13/S12 DOEA:OGCB ET:D DOEA:D

CBerlinger JERichardson CRossi

07/ /92 07/ /92 07/ /92 WP Filen  : g:\EDWARDS