Information Notice 1995-43, Failure of Bolt-Locking Device on Reactor Coolant Pump Turning Vane

Failure of Bolt-Locking Device on Reactor Coolant Pump Turning Vane
	ML031060185
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:	09/28/1995
From:	Crutchfield D; Office of Nuclear Reactor Regulation
To:	;
References
	IN-95-043, NUDOCS 9509220300
	Download: ML031060185 (8)
	v • d • e

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UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555-0001 September 28, 1995 NRC INFORMATION NOTICE 95-43: FAILURE OF THE BOLT-LOCKING DEVICE ON THE

REACTOR COOLANT PUMP TURNING VANE

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors designed by Westinghouse Electric Corporation (W).

PurDose

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

that have

notice to alert addressees to a recent event involving in the turning vane

resulted in the loss of integrity of bolt-locking devices

coolant pumps (RCPs). It is

diffuser attachment of Westinghouse reactor for applicability to

expected that recipients will review the information to avoid similar

their facilities and consider actions, as appropriate, notice are not

problems. However, suggestions contained in this information response is

NRC requirements; therefore, no specific action or written

required.

Description of Circumstances

On June 3, 1994, the licensee for the Seabrook Nuclear Power Station conducted

internals. Foreign material was

an underwater examination of reactor vessel In a subsequent video

found on the reactor vessel internals lower core plate.

of the reactor vessel and two bolt- inspection, a bolt was found on the bottom locking device was

locking devices were found on the lower core plate. One

The licensee

intact, and the other was deformed and had portions missing. and locking cups that

identified the bolt and locking devices as a cap screw

the turning vane diffuser to the

are used in the RCPs to attach and secure

thermal barrier flange.

Discussion

reactor plant

The Seabrook Plant is a four-loop Westinghouse pressurized-water

section consists.

with Westinghouse Model 93A-1 RCPs. The RCP hydraulic

and a turning

of a casing, an impeller, a diffuser adapter, a thermal barrier, and is attached to the

vane diffuser. The turning vane diffuser is stationary

thermal barrier flange by 23 bolts. The bolts are 3.8 centimeters

The ends of the

[1.5 inches] in diameter and 25 centimeters (10 inches]thelong. turning vane

bolts are threaded. The bolts are designed to secure

a preload of 2,712 newton meters

diffuser to the thermal barrier flange with device is to

[2,000 ft-lbs] of torque. The function of the bolt locking

bolt preload. The locking

prevent bolt rotation and subsequent loss of members

devices are fabricated from 304 stainless steel and are cylindrical

9509220300 at OA

°

PDR ItE 1aiowL.. 95--oqaSoo

v-" IN 95-43 September 28, 1995 with a single longitudinal split. The locking devices are inserted into the

and the counterbore for

annulus formed by the outer diameter of the bolt headThe spring action of the

the bolt head machined in the turning vane flange. on the cylinder into

locking device cylinder is designed to snap two bossesfunction of the locking

mating holes in the counterbore. The anti-rotation

of the cylinder at two

device is accomplished by staking the top edge and locking devices are

locations into slots in the bolt head. The boltspump but are not part of the

exposed to the reactor coolant fluid within the

reactor coolant system pressure boundary.

four RCPs were inspected to

During the 1994 Seabrook refueling outage, all bolt one of the locking

determine the origin of the loose parts. The 1B,3 and and the other locking

devices found in the vessel were traced to RCP were detected on some

device was from RCP *D." Various degrees of degradation

postulated that the bolt and

locking devices in all four RCPs. The licensee as a result of

the locking devices dropped into the turning vaneofdiffuser

preload torque on the

degradation of the locking devices and the loss by thethe cold-leg flow stream

bolt. The bolt and locking devices were carried core support plate. The

into the reactor vessel lower head and to the lower four RCPs with a new

licensee replaced the bolts and locking devices on all

design.

of the bolt was

The degradation of the locking device and the release The evaluation

evaluated by the licensee with assistance from Westinghouse.

dated January 16, 1995.

is documented in Licensee Event Report No. 94-010-01, screw and locking cups

The root cause of the release of the turning vane cap considering the affects

was attributed to the original design not adequately turning vane cap screw.

of flow-induced vibration on the locking cup and the caused the locking cups to

The licensee postulated that flow-induced vibration subsequently backed

erode and release from the turning vane. The cap screw the effects of vibration

out as a result of the loss of the preload torque and

and gravity.

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

notice, please contact

you have any questions about the information in this Office of Nuclear

the technical contact listed below or the appropriate

Reactor Regulation (NRR) project manager.

nnWM. Crutch rector

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contact: Francis Grubelich, NRR

(301) 415-2784 Attachment:

List of Recently Issued NRC Information Notices

Hi A

')ciachment

IN 95-43 September 28, 1995 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

95-42 Commission Decision on the 09/22/95 All holders of OLs or CPs

Resolution of Generic for nuclear power reactors.

Issue 23, 'Reactor Coolant

Pump Seal Failure'

95-41 Degradation of Ventilation 09/22/95 All holders of OLs or CPs

System Charcoal Resulting for nuclear power reactors.

from Chemical Cleaning of

Steam Generators

95-40 Supplemental Information 09/20/95 All holders of OLs or CPs

to Generic Letter 95-03, for nuclear power reactors.

OCircumferential Cracking

of Steam Generator Tubes"

95-39 Brachytherapy Incidents 09/19/95 All U.S. Nuclear Regulatory

Involving Treatment Commission Medical

Planning Errors Licensees.

95-38 Degradation of Boraflex 09/08/95 All holders of OLs or CPs

Neutron Absorber in for nuclear power reactors.

Spent Fuel Storage Racks

95-37 Inadequate Offsite Power 09/07/95 All holders of OLs or CPs

System Voltages during for nuclear power reactors.

Design-Basis Events

95-36 Potential Problems with 08/29/95 All holders of OLs or CPs

Post-Fire Emergency for nuclear power reactors.

Lighting

95-35 Degraded Ability of 08/28/95 All holders of OLs or CPs

Steam Generators to for pressurized water

Remove Decay Heat by reactors (PWRs).

Natural Circulation

95-34 Air Actuator and Supply 08/25/95 All holders of OLs or CPs

Air Regulator Problems in for nuclear power reactors.

Copes-Vulcan Pressurizer

Power-Operated Relief Valves

OL - Operating License

CP - Construction Permit

IN 95-43 s'-' September 28, 1995 annulus formed by the outer diameter of the bolt head and the counterbore for

the bolt head machined in the turning vane flange. The spring action of the

locking device cylinder is designed to snap two bosses on the cylinder into

mating holes in the counterbore. The anti-rotation function of the locking

device is accomplished by staking the top edge of the cylinder at two

locations into slots in the bolt head. The bolts and locking devices are

exposed to the reactor coolant fluid within the pump but are not part of the

reactor coolant system pressure boundary.

During the 1994 Seabrook refueling outage, all four RCPs were inspected to

determine the origin of the loose parts. The bolt and one of the locking

devices found in the vessel were traced to RCP "B." and the other locking

device was from RCP "D." Various degrees of degradation were detected on some

locking devices in all four RCPs. The licensee postulated that the bolt and

the locking devices dropped into the turning vane diffuser as a result of

degradation of the locking devices and the loss of the preload torque on the

bolt. The bolt and locking devices were carried by the cold-leg flow stream

into the reactor vessel lower head and to the lower core support plate. The

licensee replaced the bolts and locking devices on all four RCPs with a new

design.

The degradation of the locking device and the release of the bolt was

evaluated by the licensee with assistance from Westinghouse. The evaluation

is documented in Licensee Event Report No. 94-010-01, dated January 16, 1995.

The root cause of the release of the turning vane cap screw and locking cups

was attributed to the original design not adequately considering the affects

of flow-induced vibration on the locking cup and the turning vane cap screw.

The licensee postulated that flow-induced vibration caused the locking cups to

erode and release from the turning vane. The cap screw subsequently backed

out as a result of the loss of the preload torque and the effects of vibration

and gravity.

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

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

the technical contact 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 contact: Francis Grubelich, NRR

(301) 415-2784 Attachment: List of Recently Issued NRC Information Notices

DOCUMENT NAME: 95-43.IN *See previous concurrence 'N" = No copy

To receive a copy of this document, Indlcate In the box: TC = Copy without attachment/enclosure wEt = Copy with attachment/enclosure

Di

OFFICE PECB:DRPM EMEB:DE E EMEB:DE I E ADM:PUB IN SC/PECB:DRPM N

NAME NFields* FGrubelich* KManoly* Tech Editor* EGoodwin*

LATE 08/15/95 08/15/95 08/15/95 08/02/95 08/22/95 OFFICE C/EMEB:DE IE DD/DE E IiE PECB:DRPM IE C/PECB:DRPM I

NAME RWessman* jGLainas* BSheron* RKiessel* AChaffee*

DATE 08/22/95 08/23/95 08/23/95 09/12/95 09/14/95 OFFICE ID/DFifl4 / I I

NAME lDC ruf eld

DATE lQf /95 I

OFFICIAL RECORD COPY

IN 95-xx

K-' -September xx, 1995 annulus formed by the outer diameter of the bolt head and the counterbore for

the bolt head machined in the turning vane flange. The spring action of the

locking device cylinder is designed to snap two bosses on the cylinder into

mating holes in the counterbore. The anti-rotation function of the locking

device is accomplished by staking the top edge of the cylinder at two

locations into slots in the bolt head. The bolts and locking devices are

exposed to the reactor coolant fluid within the pump but are not part of the

reactor coolant system pressure boundary.

During the 1994 Seabrook refueling outage, all four RCPs were inspected to

determine the origin of the loose parts. The bolt and one of the locking

devices found in the vessel were traced to RCP "B," and the other locking