Information Notice 1997-02, Cracks Found in Jet Pump Riser Assembly Elbows at Boiling Water Reactors

Cracks Found in Jet Pump Riser Assembly Elbows at Boiling Water Reactors

ML031050391
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:	02/06/1997
From:	Martin T Office of Nuclear Reactor Regulation
To:
References
IN-97-002, NUDOCS 9702050049
Download: ML031050391 (10)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555-0001 February 6, 1997 NRC INFORMATION NOTICE 97-02: CRACKS FOUND IN JET PUMP RISER ASSEMBLY

ELBOWS AT BOILING WATER REACTORS

Addressees

All holders of operating licenses or construction permits for boiling water nuclear power

reactors (BWR) models 3, 4, 5 and 6 (BWRI3-6), except those licenses that have been

amended to possession-only status.

Purpose

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

addressees that cracking has been detected in a jet pump riser assembly at a location not

previously known to have cracks. It is expected that recipients will review the information for

applicability to their facilities and consider actions, as appropriate, to detect or 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

On November 26, 1996, General Electric Nuclear Energy (GENE) notified the NRC staff

about cracking recently discovered in jet pump riser assembly elbows at a foreign BWR plant.

The plant is approximately 25 years old. Cracks were discovered in 2 of the 10 jet pump

riser assembly elbows while plant personnel were performing a visual examination (VT-1)

using a remote underwater camera. The cracks were circumferential cracks in the 10-inch

piping and were approximately 83 mm 13.27 in] and 112 mm [4.41 in] in length. No depth

measurements were obtained because techniques for volumetric examination of this location

do not currently exist.

As a result of the cracking found in the foreign BWR, GENE issued Service Information Letter

(SIL) 605, "Jet Pump Riser Pipe Cracking," dated December 6, 1996, that provides

recommendations for inspection and detection of jet pump riser pipe cracking [Accession

No. 9612190076].

On January 15, 1997, the licensee for LaSalle Unit 2 notified the NRC staff about cracking

found during its inspection of jet pump riser assembly elbows. The licensee, in performing

visual inspections (enhanced VT-1) as recommended in GENE's SIL 605, found three

970 00 I01 P DE0PS AJOTICE q7-o0o2 17026co

IN 97-02 February 6, 1997 indications in 2 of the 10 jet pump riser assembly elbows. Preliminary information provided

to the NRC staff suggests that the indications ranged in length from approximately 20 mm to

150 mm [0.75 to 6 inches]. No depth measurements were taken. The smallest indication

had an axial orientation; the other two indications were circumferential.

Discussion

Jet pumps are part of the reactor coolant recirculation system in BWR/3-6 plants. They are

installed in the annulus between the core shroud and the reactor pressure vessel (RPV), and

each vessel contains between 12 and 24 jet pumps. Most BWRs have 20 jet pumps. There

are several BWR jet pump designs; however, the basic jet pump configuration is the same for

all plants. Figure 1 is a schematic that shows the configuration of a typical jet pump and

identifies the major components.

Each jet pump consists of a riser assembly, two inlet-mixer assemblies, two diffuser

assemblies, and a riser brace. The riser assembly elbow is a 10-inch, 90 degree short radius

elbow, fabricated from Type 304 stainless steel. It is welded to the recirculation inlet nozzle

thermal sleeve. The riser assembly is supported near the top by the riser brace, which is

welded to the riser pipe and to pads on the RPV wall (some plants have two riser braces for

each riser). Lateral support is also provided by the jet pump restrainer brackets which attach

the adjacent jet pump inlet mixers to the riser. The entrance end of each inlet-mixer

assembly is clamped to the top of the riser transition piece by the beam-bolt assembly. The

exit end of the inlet-mixer forms a slip joint with the entrance end of the diffuser. This

interface between the inlet mixers and the diffusers provides some additional lateral support

to the riser. The top of the slip joint is located near the bottom of the fuel; the exact elevation

of the slip joint is plant specific.

The cracking in both the foreign BWR and the LaSalle Unit 2 occurred in the heat-affected

zone of the weld connecting the jet pump riser elbow to a thermal sleeve. The

characteristics of the cracking are indicative of intergranular stress corrosion cracking

(IGSCC).

Separation of the jet pump riser piping could have a potential safety impact on some BWR

plants under certain accident conditions. If the jet pump riser piping were to separate under

normal operating conditions, there does not appear to be a safety concern in that the loss of

a jet pump assembly would not cause a plant to lose its capability to safely shut down.

According to GENE, a loss of one jet pump assembly would be detected by plant operators.

The BWR Owners Group Vessel and Intemals Project (BWRVIP) is working closely with

GENE and has provided a safety assessment, "Assessment of BWR Jet Pump Riser Elbow to

---

IN 97-02 February 6, 1997 Thermal Sleeve Weld Cracking (BWRVIP-28)," dated December 1996, to the NRC staff

[Accession No. 9701030009].

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.

signed by D.B. Matthews

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: C. E. Carpenter, Jr., NRR

(301) 415-2169 E-mail: cecenrc.gov

Kerri A. Kavanagh, NRR

(301) 415-3743 E-mail: kakenrc.gov

Attachments:

1. Jet Pump Assembly Schematic

2. List of Recently Issued NRC Information Notices

II d I -

IN 97-02 February 6, 1997 Thermal Sleeve Weld Cracking (BWRVIP-28)," dated December 1996, to the NRC staff

[Accession No. 9701030009].

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.

original signed by D.B. Matthews

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: C. E. Carpenter, Jr., NRR

(301) 415-2169 E-mail: cecenrc.gov

Kerri A. Kavanagh, NRR

(301) 415-3743 E-mail: kakenrc.gov

Attachments:

1. Jet Pump Assembly Schematic

2. List of Recently Issued NRC Information Notices

Tech Editor has reviewed and concurred on 01/08/97

97-02.IN

• See Previous Concurrence

DOCUMENT NAME:

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OFFICE TECH CONTS PECB:BC DRPM:D

NAME CECarpenter* AEChaffee* TTiMartin

KAKavanagh* l

DATE 01/09/97 01/27/97 02/04/97

01/10/97 _______

OFFICIAL RECORD COPY

I.

Attachment 2 IN 97-02 February 6, 1997 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

97-01 Improper Electrical Ground- 01/08/97 All holders of OLs

ing Results in Simultaneous or CPs for nuclear

Fires in the Control Room power reactors

and the Safe-Shutdown Equip- ment Room

96-72 Undetected Failure that 12/24/96 All teletherapy

May Occur During Patient licensees

Treatments with Teletherapy

Devices

96-71 Licensee Response to Indi- 12/27/96 All holders of OLs

cations of Tampering, Van- or CPs for nuclear

dalism, or Malicious Mis- power reactors

chief

96-70 Year 2000 Effect on Computer 12/24/96 All U.S. Nuclear

System Software Regulatory Commission

licensees, certificate

holders, and registrants

96-69 Operator Actions Affecting 12/20/96 All holders of OLs

Reactivity or CPs for nuclear

power reactors

96-68 Incorrect Effective Diaphragm 12/19/96 All holders of OLs

Area Values in Vendor Manual or CPs for nuclear

Result in Potential Failure power reactors

of Pneumatic Diaphragm

Actuators

96-67 Vulnerability of Emergency 12/19/96 All holders of OLs

Diesel Generators to Fuel or CPs for nuclear

Oil/Lubricating Oil Incom- power reactors

patibility

OL = Operating License

CP = Construction Permit

• . IN 97-02 February 6, 1997 December 1996, to the NRC staff

Thermal Sleeve Weld Cracking (BWRVIP-28)," dated

[Accession No. 9701030009].

written response. If you have any

This information notice requires no specific action or

contact one of the technical contacts

questions about the information in this notice, please Regulation (NRR) project manager.

listed below or the appropriate Office of Nuclear Reactor

original signed by D.B. Matthews

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: C. E. Carpenter, Jr., NRR

(301) 415-2169 E-mail: cec@nrc.gov

Kerri A. Kavanagh, NRR

(301) 415-3743 E-mail: kak@nrc.gov

Attachments:

1. Jet Pump Assembly Schematic

2. List of Recently Issued NRC Information Notices

Tech Editor has reviewed and concurred on 01/08197 * See Previous Concurrence

DOCUMENT NAME: 97-02.IN

box: 'C' - Copy w/o

To receliv a copy of this document. Indicate hI the

copy

attachment/enclosure 'E' - Copy w/sttachment/encloswSe 'N - No

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OFFICE TECH CONTS BCDRPM:

IIAM IrI-rarnantPr* IAEChaffee* ITTMarg F11/

8 s - /IN 97- January , 1997 Page 3 of/

Thermal Sleeve Weld Cracking (BWRVIP-28)," dated December 1996, to NRC staff

[Accession No. 9701030009].

This information notice requires no specific action or written re nse. If you have any

questions about the information in this notice, please conta one of the technical -contacts

listed below or the appropriate Office of Nuclear Reacto egulation (NRR) project manager.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: C. E. C nter, Jr., NRR

(31 415-2169

-mail: cec@nrc.gov

Kerri A. Kavanagh, NRR

(301) 415-3743 E-mail: kak@nrc.gov

Attachme s:

1. Jet ump Assembly Schematic

2. Li of Recently Issued NRC Information Notices

DOCUMENT NAME: G:\BWRVIP\RISER.IN

• See Previous Concurrence

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attachment/enclosure "E" - Copy with attachment/enclosure "N" - No copy

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Thermal Sleeve Weld Cracking (BWRVIP-28)," dated December 1996, to the NRC

[Accession No. 9701030009]. GOE-avei -ealuated b, the

NRG-"f

have any

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

questions about the information in this notice, please contact one of the technical contacts

manager.

listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: C. E. Carpenter, Jr., NRR

(301) 415-2169 E-mail: cecenrc.gov

Kerri A. Kavanagh, NRR

(301) 415-3743 E-mail: kak@nrc.gov

Attachments:

1. Jet Pump Assembly Schematic

2. List of Recently Issued NRC Information Notices

• See Previous Concurrence

DOCUMENT NAME: G:\BWRVIP\RISER.IN "C" * Copy without

of this document, indicate in the box:

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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.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: C. E. Carpenter, Jr.

(301) 415-2169 e-mail: cec@nrc.gov

Kerr1 A. Kavanagh, SRXB

(301) 415-3743 e-mail: kak~nrc.gov

DISTRIBUTION: see next page

G:\BWRVIP\RISER.IN

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plants have two riser braces for each riser). Lateral support is also

provided by the Jet pump restrainer brackets which attach the adjacent jet

pump inlet mixers to the riser. The entrance end of each inlet-mixer assembly

is clamped to the top of the riser transition piece by the beam-bolt assembly.

The exit end of the inlet-mixer forms a slip Joint with the entrance end of

the diffuser. This interface between the inlet mixers and Pe diffusers

provid s some additional lateral support to the riser. Th top of the slip

joint I located near the bottom of the fuel;,the exact evation of the slip

joint is lant specific.

The crackin occurred in the heat-affected zone of e weld connecting the jet

pump riser e ow to a thermal sleeve. The charac ristics of the cracking are

indicative of tergranular stress corrosion cr king (IGSCC).

GE has issued Serv e Information Letter (SI 605, 'Jet Pump Riser Pipe

Cracking," dated Dec ber 6, 1996, that pr ides recommendations for

inspection and detecti of Jet pump ris pipe cracking.

The BWR Owners Group Vess and Inter ls Project (BWRVIP) is working closely

with GENE and has provided ropri ary safety assessment, "Assessment of BWR

Jet Pump Riser Elbow to Therma S1 eve Weld Cracking (BWRVIP-28),' dated

December 23, 1996, to the NRC st f.

The NRC staff is evaluating B VIP-28 d GENE SIL 605 to determine whether

additional generic actions a e necessar

This information notice r uires no specific ction or written response. If

you have any questions a out the information I this notice, please contact

one of the technical c tacts listed below or th ppropriate Office of

Nuclear Reactor Regul ion (NRR) project manager.

Thomas T. Martin, Dire or

Division of Reactor Pro am Management

Office of Nuclear Reactor egulation

Technical ntacts: C. E. Carpenter, Jr. Kerrl A. Kavanag SRXB

(301) 415-2169 (301) 415-3743 e-mail: cec~nrc.gov e-mail: kak4nrc.gov

see next page

DOCUMENT AME: Gs\BWRVIP\RISER.IN

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