1801 R0 XI.M9

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XI.M9 BWR VESSEL INTERNALS

Program Description

The program includes (a) inspection and flaw evaluation in conformance with the guidelines of applicable and staff-approved boiling water reactor vessel and internals project (BWRVIP) documents and (b) monitoring and control of reactor coolant water chemistry in accordance with the guidelines of BWRVIP-29 (Electric Power Research Institute [EPRI] TR-103515)(Archived) to ensure the long-term integrity and safe operation of boiling water reactor (BWR) vessel internal components.

Evaluation and Technical Basis

1. Scope of Program: The program is focused on managing the effects of crack initiation and growth due to stress corrosion cracking (SCC), intergranular stress corrosion cracking (IGSCC), or irradiation assisted stress corrosion cracking (IASCC). The program contains preventive measures to mitigate SCC, IGSCC, or IASCC; inservice inspection (ISI) to monitor the effects of cracking on the intended function of the components; and repair and/or replacement as needed to maintain the ability to perform the intended function.

The BWRVIP documents provide generic guidelines intended to present the applicable inspection recommendations to assure safety function integrity of the subject safety-related reactor pressure vessel internal components. The guidelines include information on component description and function; evaluate susceptible locations and safety consequences of failure; provide recommendations for methods, extent, and frequency of inspection; discuss acceptable methods for evaluating the structural integrity significance of flaws detected during these examinations; and recommend repair and replacement procedures.

The various applicable BWRVIP guidelines are as follows:

Core shroud: BWRVIPs-07(Archived), -63(Archived), and -76(Archived) provide guidelines for inspection and evaluation; BWRVIP-02(Archived), Rev. 2, provides guidelines for repair design criteria.

Core plate: BWRVIP-25(Archived) provides guidelines for inspection and evaluation; BWRVIP-50(Archived) provides guidelines for repair design criteria.

Shroud support: BWRVIP-38, provides guidelines for inspection and evaluation; BWRVIP-52(Archived) provides guidelines for repair design criteria.

Low-pressure coolant injection (LPCI) coupling: BWRVIP-42(Archived) provides guidelines for inspection and evaluation; BWRVIP-56(Archived) provides guidelines for repair design criteria.

Top guide: BWRVIP-26(Archived) provides guidelines for inspection and evaluation; BWRVIP-50(Archived) provides guidelines for repair design criteria.

Core spray: BWRVIP-18(Archived) provides guidelines for inspection and evaluation; BWRVIP-16(Archived) and 19(Archived) provides guidelines for replacement and repair design criteria, respectively.

Jet pump assembly: BWRVIP-41(Archived) provides guidelines for inspection and evaluation; BWRVIP-51(Archived) provides guidelines for repair design criteria.

Control rod drive (CRD) housing: BWRVIP-47(Archived) provides guidelines for inspection and evaluation; BWRVIP-58(Archived) provides guidelines for repair design criteria.

Lower plenum: BWRVIP-47(Archived) provides guidelines for inspection and evaluation; BWRVIP-57(Archived) provides guidelines for repair design criteria for instrument penetrations.

In addition, BWRVIP-44(Archived) provides guidelines for weld repair of nickel alloys; BWRVIP-45 provides guidelines for weldability of irradiated structural components.

2. Preventive Actions: Maintaining high water purity reduces susceptibility to cracking due to SCC or IGSCC. Reactor coolant water chemistry is monitored and maintained in accordance with the guidelines in BWRVIP-29 (EPRI TR-103515)(Archived). The program description and evaluation, and technical basis of monitoring and maintaining reactor water chemistry are presented in Chapter XI.M2, "Water Chemistry."

3. Parameters Monitored/Inspected: The program monitors the effects of cracking on the intended function of the component by detection and sizing of cracks by inspection in accordance with the guidelines of applicable and approved BWRVIP documents and the requirements of the American Society of Mechanical Engineers (ASME) Code, Section XI, Table IWB 2500-1 (1995 edition through the 1996 addenda). An applicant may use the guidelines of BWRVIP-62(Archived) for inspection relief for vessel internal components with hydrogen water chemistry.

4. Detection of Aging Effects: The extent and schedule of the inspection and test techniques prescribed by the applicable and approved BWRVIP guidelines are designed to maintain structural integrity and ensure that aging effects will be discovered and repaired before the loss of intended function. Inspection can reveal crack initiation and growth. Vessel internal components are inspected in accordance with the requirements of ASME Section Xl, Subsection IWB, examination category B-N-2. The ASME Section XI inspection specifies visual VT-1 examination to detect discontinuities and imperfections, such as cracks, corrosion, wear, or erosion, on the surfaces of components. This inspection also specifies visual VT-3 examination to determine the general mechanical and structural condition of the component supports by (a) verifying parameters, such as clearances, settings, and physical displacements, and (b) detecting discontinuities and imperfections, such as loss of integrity at bolted or welded connections, loose or missing parts, debris, corrosion, wear, or erosion.

The applicable and approved BWRVIP guidelines recommend more stringent inspections, such as enhanced visual VT-I examinations or ultrasonic methods of volumetric inspection, for certain selected components and locations. The nondestructive examination (NDE) techniques appropriate for inspection of BWR vessel internals and their implementation needs, including the uncertainties inherent in delivering and executing NDE techniques in a BWR, are included in BWRVIP-03(Archived).

5. Monitoring and Trending: Inspections scheduled in accordance with the applicable and approved BWRVIP guidelines provide timely detection of cracks. The scope of examination expansion and reinspection beyond the baseline inspection are required if flaws are detected.

6. Acceptance Criteria: Any indication detected is evaluated in accordance with ASME Section XI or the applicable staff-approved BWRVIP guidelines. Approved BWRVIP-14(Archived), BWRVIP-59(Archived), and BWRVIP-60(Archived) documents provide guidelines for evaluation of crack growth in stainless steels (SSs), nickel alloys, and low-alloy steels, respectively.

7. Corrective Actions: Repair and replacement procedures are equivalent to those requirements in ASME Section Xl. Repair and replacement is in conformance with the applicable and approved BWRVIP guidelines listed above. As discussed in the appendix to this report, the staff finds that licensee implementation of the guidelines in the staff-approved BWRVIP reports will provide an acceptable level of quality for inspection and flaw evaluation of the safety-related components addressed in accordance with 10 CFR Part 50, Appendix B.

8. Confirmation Process: Site quality assurance (QA) procedures, review and approval processes, and administrative controls are implemented in accordance with the requirements of 10 CFR Part 50, Appendix B. As discussed in the appendix to this report, the staff finds that licensee implementation of the guidelines in the staff-approved BWRVIP reports will provide an acceptable level of quality for inspection and flaw evaluation of the safety-related components addressed in accordance with the 10 CFR Part 50, Appendix B, confirmation process and administrative controls.

9. Administrative Controls: See Item 8, above.

10. Operating Experience: Extensive cracking has been observed in core shrouds at both horizontal (US Nuclear Regulatory Commission (US NRC) Generic Letter (GL) 94-03) and vertical (US NRC Information Notice (IN) 97-17) welds. It has affected shrouds fabricated from Type 304 and Type 304L SS, which is generally considered to be more resistant to SCC. Weld regions are most susceptible, although it is not clear whether this is due to sensitization and/or impurities associated with the welds or the high residual stresses in the weld regions. This experience is reviewed in US NRC GL 94-03 and NUREG-1544; some experiences with visual inspections are discussed in US NRC IN 94-42.

Both circumferential (US NRC IN 88-03) and radial cracking (US NRC IN 92-57) has been observed in the shroud support access hole cover made from Alloy 600. Instances of cracking in core spray spargers have been reviewed in US NRC IE Bulletin 80-13.

Cracking of the core plate has not been reported, but the creviced regions beneath the plate are difficult to inspect. The US NRC IN 95-17 discusses cracking in top guides of United States and overseas BWRs. Related experience in other components is reviewed in US NRC GL 94-03 and NUREG-1544. Cracking has also been observed in the top guide of a Swedish BWR.

Instances of cracking have occurred in the jet pump assembly (US NRC IE Bulletin 80-07), hold-down beam (US NRC IN 93-101), and jet pump riser pipe elbows (US NRC IN 97-02).

Cracking of dry tubes has been observed at 14 or more BWRs. The cracking is intergranular and has been observed in dry tubes without apparent sensitization, suggesting that IASCC may also play a role in the cracking.

The program guidelines outlined in applicable and approved BWRVIP documents are based on evaluation of available information, including BWR inspection data and information on the elements that cause SCC, IGSCC, or IASCC, to determine which components may be susceptible to cracking. Implementation of the program provides reasonable assurance that crack initiation and growth will be adequately managed so the intended functions of the vessel internal components will be maintained consistent with the current licensing basis (CLB) for the period of extended operation.

References

10 CFR 50.55a, Codes and Standards, Office of the Federal Register, National Archives and Records Administration, 2000.

ASME Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, ASME Boiler and Pressure Vessel Code, 1995 edition through the 1996 addenda, American Society of Mechanical Engineers, New York, NY.

BWRVIP-02, BWR Vessel and Internals Project, BWR Core Shroud Repair Design Criteria, Rev. 2,(Archived) BWRVIP and Electric Power Research Institute, Palo Alto, CA, March 7, 2000.

BWRVIP-03, BWR Vessel and Internals Project, Reactor Pressure Vessel and Internals Examination Guidelines, (EPRI TR-105696 R1, March 30, 1999)(Archived), Final Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-03(Archived), July 15, 1999.

BWRVIP-07, BWR Vessel and Internals Project, Guidelines for Reinspection of BWR Core Shrouds, (EPRI TR-105747, Feb. 29, 1996)(Archived), Final Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-07(Archived), April 27, 1998.

BWRVIP-14, Evaluation of Crack Growth in BWR Stainless Steel RPV Internals, (EPRI TR-105873, July 11, 2000)(Archived), Final Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-14(Archived), December 3, 1999.

BWRVIP-16, Internal Core Spray Piping and Sparger Replacement Design Criteria, (EPRI TR-106708)(Archived), BWRVIP and Electric Power Research Institute, Palo Alto, CA, March 7, 2000.

BWRVIP-18, BWR Vessel and Internals Project, BWR Core Spray Internals Inspection and Flaw Evaluation Guidelines, (EPRI TR-106740, July 1996)(Archived), Final License Renewal Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-18(Archived) for Compliance with the License Renewal Rule (10 CFR Part 54), December 7, 2000.

BWRVIP-19, Internal Core Spray Piping and Sparger Repair Design Criteria, (EPRI TR-106893)(Archived), BWRVIP and Electric Power Research Institute, Palo Alto, CA, March 7, 2000.

BWRVIP-25, BWR Vessel and Internals Project, BWR Core Plate Inspection and Flaw Evaluation Guidelines, (EPRI TR-107284, Dec. 1996)(Archived), Final License Renewal Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-25(Archived) for Compliance with the License Renewal Rule (10 CFR Part 54), December 7, 2000.

BWRVIP-26, BWR Vessel and Internals Project, Top Guide Inspection and Flaw Evaluation Guidelines, (EPRI TR-107285, Dec. 1996)(Archived), Final License Renewal Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-26(Archived) for Compliance with the License Renewal Rule (10 CFR Part 54), December 7, 2000.

BWRVIP-29, BWR Vessel and Internals Project, BWR Water Chemistry Guidelines-1993 Revision, Normal and Hydrogen Water Chemistry, (EPRI TR-103515)(Archived), Electric Power Research Institute, Palo Alto, CA, February 1994.

BWRVIP-38, BWR Vessel and Internals Project, BWR Shroud Support Inspection and Flaw Evaluation Guidelines, (EPRI TR-108823, September 1997), Final License Renewal Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-38 for Compliance with the License Renewal Rule (10 CFR Part 54), March 1, 2001.

BWRVIP-41, BWR Vessel and Internals Project, BWR Jet Pump Assembly Inspection and Flaw Evaluation Guidelines, (EPRI TR-108728, October 1997)(Archived), Final License Renewal Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-41(Archived) for Compliance with the License Renewal Rule (10 CFR Part 54), June 15, 2001.

BWRVIP-42, BWR Vessel and Internals Project, BWR LPCI Coupling Inspection and Flaw Evaluation Guidelines, (EPRI TR-108726, December 1997)(Archived), Final License Renewal Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-42(Archived) for Compliance with the License Renewal Rule (10 CFR Part 54), January 9, 2001.

BWRVIP-44, Underwater Weld Repair of Nickel Alloy Reactor Vessel Internals, (EPRI TR-108708, April 3, 2000)(Archived), Final Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-44(Archived), June 9, 1999.

BWRVIP-45, Weldability of Irradiated L WR Structural Components, (EPRI TR-108707), BWRVIP and Electric Power Research Institute, Palo Alto, CA, June 14, 2000.

BWRVIP-47, BWR Vessel and Internals Project, BWR Lower Plenum Inspection and Flaw Evaluation Guidelines, (EPRI TR-108727, December 1997)(Archived), Final License Renewal Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-47(Archived) for Compliance with the License Renewal Rule (10 CFR Part 54), December 7, 2000.

BWRVIP-50, Top Guide/Core Plate Repair Design Criteria, (EPRI TR-108722)(Archived), BWRVIP and Electric Power Research Institute, Palo Alto, CA, April 3, 2000.

BWRVIP-51, Jet Pump Repair Design Criteria, (EPRI TR-108718, March 7, 2000)(Archived), Initial Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-51(Archived), October 28, 2000.

BWRVIP-52, Shroud Support and Vessel Bracket Repair Design Criteria, (EPRI TR-108720, June 26, 1998)(Archived), Initial Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-52(Archived), November 2, 2000.

BWRVIP-56, LPCI Coupling Repair Design Criteria, (EPRI TR-108717)(Archived), BWRVIP and Electric Power Research Institute, Palo Alto, CA, March 24, 2000.

BWRVIP-57, Instrument Penetration Repair Design Criteria, (EPRI TR-108721)(Archived), BWRVIP and Electric Power Research Institute, Palo Alto, CA, March 24, 2000.

BWRVIP-58, CRD Internal Access Weld Repair, (EPRI TR-108703)(Archived), BWRVIP and Electric Power Research Institute, Palo Alto, CA, March 7, 2000.

BWRVIP-59, Evaluation of Crack Growth in BWR Nickel-Base Austenitic Alloys in RPV Internals, (EPRI TR-108710)(Archived), BWRVIP and Electric Power Research Institute, Palo Alto, CA, March 24, 2000.

BWRVIP-60, BWR Vessel and Internals Project, Evaluation of Crack Growth in BWR Low Alloy Steel RPV Internals, (EPRI TR-108709, April 14, 2000)(Archived), Final Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-60(Archived), July 8, 1999.

BWRVIP-62, BWR Vessel and Internals Project, Technical Basis for Inspection Relief for BWR Internal Components with Hydrogen Injection, (EPRI TR-108705)(Archived), BWRVIP and Electric Power Research Institute, Palo Alto, CA, March 7, 2000.

BWRVIP-63, BWR Vessel and Internals Project, Shroud Vertical Weld Inspection and Evaluation Guidelines, (EPRI TR-113117, Feb. 29, 2000)(Archived), Initial Safety Evaluation Report by the Office of Nuclear Reactor Regulation for BWRVIP-63(Archived), April 18, 2000.

BWRVIP-76, BWR Vessel and Internals Project, BWR Core Shroud Inspection and Flaw Evaluation Guidelines, (EPRI TR-114232, November 1999)(Archived).

US NRC Generic Letter 94-03, Intergranular Stress Corrosion Cracking of Core Shrouds in Boiling Water Reactors, U.S. Nuclear Regulatory Commission, July 25, 1994.

US NRC IE Bulletin No. 80-07, BWR Jet Pump Assembly Failure, U.S. Nuclear Regulatory Commission, April 4, 1980.

US NRC IE Bulletin No. 80-13, Cracking in Core Spray Spargers, U.S. Nuclear Regulatory Commission, May 12, 1980.

US NRC IE Bulletin No. 80-07, Supplement 1, BWR Jet Pump Assembly Failure, U.S. Nuclear Regulatory Commission, May 13, 1980.

US NRC Information Notice 88-03, Cracks in Shroud Support Access Hole Cover Welds, U.S. Nuclear Regulatory Commission, February 2, 1988.

US NRC Information Notice 92-57, Radial Cracking of Shroud Support Access Hole Cover Welds, U.S. Nuclear Regulatory Commission, August 11, 1992.

US NRC Information Notice 93-101, Jet Pump Hold-Down Beam Failure, U.S. Nuclear Regulatory Commission, December 17, 1993.

US NRC Information Notice 94-42, Cracking in the Lower Region of the Core Shroud in Boiling Water Reactors, U.S. Nuclear Regulatory Commission, June 7, 1994.

US NRC Information Notice 95-17, Reactor Vessel Top Guide and Core Plate Cracking, U.S. Nuclear Regulatory Commission, March 10, 1995.

US NRC Information Notice 97-02, Cracks Found in Jet Pump Riser Assembly Elbows at Boiling Water Reactors, U.S. Nuclear Regulatory Commission, February 6, 1997.

US NRC Information Notice 97-17, Cracking of Vertical Welds in the Core Shroud and Degraded Repair, U.S. Nuclear Regulatory Commission, April 4,1997.

NUREG-1544, Status Report: Intergranular Stress Corrosion Cracking of BWR Core Shrouds and Other Internal Components, U.S. Nuclear Regulatory Commission, March 1996.

Boiling Water Reactor

Boiling Water Reactor Vessel Internals Program - The BWRVIP is an industry program for General Electric boiling water reactors that has developed procedures for performing inspections of reactor vessel internals.

Electric Power Research Institute

Stress Corrosion Cracking

American Society of Mechanical Engineers

Non Destructive Examination

Quality Assurance

United States of America

Nuclear Regulatory Commission - The US federal government agency that regulates nuclear power plants

US NRC regulatory guide

Current Licensing Basis - 10 CFR 54.3 under references

Reactor Pressure Vessel