ML20210H627

Summary of 990622 Meeting with EOI Re NRC Briefing by RBS on Issues Associated with Root Cause Investigation Into Fuel Cladding Failures That Occurred During Recent Cycle 8 Operation.List of Attendees Provided

ML20210H627
Person / Time
Site:	River Bend
Issue date:	07/29/1999
From:	Robert Fretz NRC (Affiliation Not Assigned)
To:	NRC (Affiliation Not Assigned)
References
NUDOCS 9908040061
Download: ML20210H627 (14)

Text

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s, rs UNITED STATES j

,j NUCLEAR REGULATORY COMMISSION g

f WASHINGTON, D.C. 20066-0001 g,**.***/

July 29,1999 LICENSEE:

Entergy Operations, Inc.

FACILITY:

River Bend Station, Unit 1

SUMMARY

OF MEETING BETWEEN THE NUCLEAR REGULATORY COMMISSION (NRC) STAFF AND ENTERGY OPERATIONS, INC. (EOI),

RIVER BEND STATION MANAGEMENT, JUNE 22,1999 On Tuesday, June 22,1999, a meeting was held between members of the NRC staff and representatives of EOl, the licensee for the River Bend Station (RBS). The purpose of the meeting was to permit representatives from RBS to brief the NRC staff on, and to discuss issues associated with, the root cause investigation into fuel cladding failures that occurred during the recent cycle 8 operation. A portion of the meeting involved discussions pertaining to proprietary information and was closed to the public. The meeting lasted approximately 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.

The meeting began at 9:00 a.m. In the Commissioners' Hearing Room located at NRC Headquarters, Rockville, Maryland. A list of meeting attendees is provided as Enclosure 1 to this summary. EOl presented a nonproprietary information overview of their root cause investigation. Topics during this session included:

Background

Inspection Findings Licensee's Response Evaluation Approach Core Design a

Conclusions EOl opened by characterizing the issue as (1) a higher than-expected and non-uniform deposition of corrosion products on the fuel pins, and (2) the occurrence of fuel cladding f

perforations in several once-burned, higher heat flux fuel rod locations. A total of seven fuel j

bundles were discovered with cladding perforations, which correlated to the number of

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suspected failures suspected prior to the plant shutting down in April 1999. All seven bundles were "first burned" fuel coming from the "HGE" batch. The cladding perforations observed in these fuel bundles were attributed to an insulating thermal barrier failure mechanism.

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Following an exchange of background information and initial inspection findings, EOl reviewed 5) its organizational response, causal investigation approach, and various core design issues, y

EOl formed a root cause investigation team, comprising of members from EOi, General Electric (GE), Electric Power Research institute (EPRI), and other independent consultants. The investigation was headed by Mr. Dan Pace, Director, Engineering (RBS).

M 9900040061 990729 PDR ADOCK 05000458 P

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2 EOl continued with a discussion on the various differences between Cycle 7 and Cycle 8 operations. Some of the differences included the removal of low cross-linked resins from the demineralizers, initiation of zine injection into the primary water, use of the extended operating domain-Maximum Extended Load Line Limit Analysis (MELLA)-operating strategy, extended control blade sequence exchange intervals, and higher iron and copper concentrations in the reactor water than in previous cycles. This discussion was followed by an overview of various chemistry issues.

Based upon the information uncovered to date, as well as the conclusions drawn by EOl and outside consultants, EOl has determined that the most probable cause of the fuel cladding perforations was a result of " thermally-induced accelerated corrosion, due to the combined effects of elevated iron and copper deposits with a chemistry excursion early in the operating cycle." Consequently, EOl has decided to undertake the following actions:

1.

Remove all once-burned fuel assemblies from the HGE batch; 2.

Redesign the reactor core to accommodate a new reload batch for Cycle 9; 3.

Change the RBS chemistry program to (a) reduce metals transport to the reactor, (b) improve chemistry monitoring capability, and (c) increase chemistry monitoring; 4.

Cycle 9 will operate as a "short cycle"(approximately half of the normal 18-month operating cycle); and 5.

RBS will perform confirmatory inspection during the ninth refueling outage.

The public portion of the meeting was concluded and members of the pubiic were given the opportunity to provide comments to the NRC staff. A copy of the slides used during the public, nonproprietary session are provided as Enclosure 2. The meeting reconvened with a briefing on additional details, including information requested by EOl to be considered proprietary under Title 10 of the Code of Federal Reaulations. Section 2.790. The briefing included presentations by EOl and GE.

( // o obert J. Fretz, Proje anager, Section 1 Project Directorate IV & Decommissioning Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-458

Enclosures:

1. List of Meeting Attendees

2. EOl Slide Presentation cc w/encis: See next page

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+

e River Bend Station cc:

Winston & Strawn Executive Vice President and 1400 L Street, N.W.

Chief Operating Officer Washington, DC 20005-3502 Entergy Operations, Inc.

P. O. Box 31995 Manager - Licensing Jackson, MS 39286 Entergy Operations, Inc.

River Bend Station General Manager - Plant Operations P. O. Box 220 Entergy Operations, Inc.

St. Francisville, LA 70775 River Bend Station P. O. Box 220 Senior Resident inspector St. Francisville, LA 70775 P. O. Box 1050 St. Francisville, LA 70775 Director - Nuclear Safety Entergy Operations, Inc.

President of West Feliciana River Bend Station Police Jury P. O. Box 220 P. O. Box 1921 St. Francisville, LA 70775 St. Francisville, LA 70775 Vice President - Operations Support Regional Administrator, Region IV Entergy Operations, Inc.

l U.S. Nuclear Regulatory Commission P. O. Box 31995 j

611 Ryan Plaza Drive, Suite 1000 Jackson, MS 39286-1995 j

Arlington,TX 76011 Attorney General Ms. H. Anne Plettinger State of Louisiana 3456 Villa Rose Drive P. O. Box 94095 Baton Rouge, LA 70806 Baton Rouge, LA 70804-9095 Administrator Mr. Randall K. Edington Louisiana Radiation Protection Division Vice President - Operations P. O. Box 82135 Entergy Operations, Inc.

Baton Rouge, LA 70884 2135 River Bend Station P. O. Box 220 Wise, Carter, Child & Caraway St. Francisville, LA 70775 P. O. Box 651 Jackson, MS 39205 May 1999

7,

'4

't 1

LIST OF ATTENDEES NRC - EOl MEETING ON FUEL INTEGRITY ISSUES JUNE 22,1999 i

NRC Staff Stuart Richards Project Director, Project Directorate IV & Decommissioning Dale Powers -

Chief, Engineering and-Maintenance Branch, Region IV Robert Gramm L Section Chief, Project Directorate IV, Section 1 Ralph Caruso Section Chief, Reactor Systems Branch Robert Fretz RBS Project Manager, Project Directorate IV, Section 1 Muffet Chatterton Nuclear Engineer, Reactor Systems Branch Shih-Lang Wu Nuclear Engineer, Reactor Systems Branch Joseph Donoghue Reactor Engineer, Reactor Systems Branch Anthony Ulses Nuclear Engineer, Reactor Systems Branch Edward Kendrick Reactor Engineer, Reactor Systems Branch Ronald Framm Reactor Engineer, Reactor Systems Branch H. F. Conrad Senior Materials Engineer, Materials and Chemical Engineering Branch K. Parczewski Senior Chemical Engineer, Materials and Chemical Engineering Branch Edward Goodwin Senior Reactor Engineer, Events Assessment Branch Robert Spence Reactor Systems EnD neer, Office of Nuclear Regulatory Research i

Carl Beyer NRC Consultant, Pacific Nothwest Laboratory Enterav Ooerations. Inc.

Fred Titus VP, Engineering (Corporate)

Dan Pace Director, Engineering (RBS)

Dwight Mims RBS Plant Manager Rick King Director, Nuclear Safety and Regulatory Affairs Brian Thumm Licensing Engineer David Smith Senior Engineer Jerome Holmes Manager, Radiation Protection / Chemistry C. B. Franklin Manager, Nuclear Engineering (Corporate)

Dean Burnett Chemistry Specialist General Electric Corooration G. A. Watford Manager, Nuclear Fuel Engineering G. A. Potts Fuel Performance Robert Cowan Chief Technologist Public Observers David Stellfox McGraw-Hill ENCLOSURE 1

ENCLOSURE 2 ENTERGY OPERATIONS, INC.

SLIDE PRESENTATION

i River Bend Station

)

Fuel Recovery Overview June 22,1999 Overview

- Background

- Contingency Planning Prior to the Eighth Refueling Outage (RF-8)

-Inspection Findings

- Response to Inspection Findings

- Evaluation Approach

- Core Design

- Conclusions 2

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Fuel Performance Summary Good past fuel performance prior to Cycle 8 No fuel clad perforation in over 1400 days of operation No previous corrosion-related clad perforations

• First fuel clad perfbration identified Sept.18, 1998, during Cycle 8 Seven fuel bundles total suspected before end of cycle (EOC) l

RF-8 InitialInspection Findings 1

Shutdown unit for RF-8 on 4/3/99 Performed 100% core sipping

• 7 bundles with clad perforations - all identified during Cycle 8 All were "first burned" fuel (HGE batch)

Heavier-than-expected non-uniform crud patterns

• Result : clad perforation mechanism observed was attributed to an insulating thermal barrier i

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. An industry term for corrosion and wear products

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Activated particles are referred to as " crud"

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. Crud is present in all nuclear plants 1

In a boiling water reactor (BWR), corrosion products plate out in the core because they do not carry over in the steam f

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Independent Reviews / Oversight

• EPRI-Fuel Corrosion NWT Corporation - Radiochemistry

• G. Sossi-Core Design and Licensing

• Independent Lab - Materials

• Corrective Action Review Board

• Facility Review Committee Safety Review Committee S. Levy - Entergy Nuclear Committee of the Board of Directors

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Fuel Operating Experience Review Foreign and domestic Various fuel types Search for similar conditions Parallel effort by General Electric Perspective

- Foreign and domestic occurrences

- Multiple causes

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Fuel Operating Experience Review Results

- Good team insights No fuel performance experience parallels the River Bend condition

- Fuel clad perforations typically caused by the combination of several factors Broad response treats symptoms effectively Aoot cause conclusions typically longer term i.

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Chemistry Program

= Based on BWR Water Chemistry Guidelines

• Monitors iron and copper parameters

- Reactor water

- Feedwater / condensate chemistry Identified an increase in feedwater metals average

- Higher than in previous cycles

- Within guidelines

- Related to resin usage 2t Chemistry Review

. October 15-17,1997 (during refueling outage 7 (RF-7))

- Conductivity excurrion (6.1 pS/cm peak)

- Associated with chendcals introduced by residual heat removal (RHR) heat exchanger cleaning October 24-26,1997 (startup from RF-7)

- Conductivity excursion (0.946 S/cm peak)

- Contaminants in extraction / drain piping n

1 Cause ofFuel Clad Perforations Thermally-induced accelerated corrosion, due to the combined effects of elevated iron and copper deposits with a chemistry excursion early in the operating cycle j

29 Cause ofFuel Clad Perforations cw s yFli<

Cu c-Cycle 6 f.

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$Fe7 Cu Cycle 8 EM!T6I)3 Cu BOC Excursion >

Cycle 9 g.*.?pfi'h Cu Improved feedwater treatment improved cleanup / monitoring 1s i

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Conclusions

. Quickly and accurately identified and suppressed perforated fuel rods during Cycle 8

. Extensively investigated to determine the cause and to prevent recurrence

. Determined that an insulating thermal barrier of crud caused accelerated fuel rod corrosion

. Ultimately bounded the cause in order to attsin reasonable assurance that no similar fuel clad perforations will occur

. Concluded that River Bend is safe to startto and operate a

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I

..W f@f July 29,1999 filP EOl continued with a discussion on the various differences between Cycle 7 and Cycle 8 operations. Some of the differences included the removal of low cross-linked resins from the

' demineralizers, initiation of zinc injection into the primary water, use of the extended operating

- domain-Maximum Extended Load Line Limit Analysis (MELLA)-operating strategy, extended control blade sequence exchange intervals, and higher iron and copper concentrations in the reactor water than in previous cycles. This discussion was followed by an overview of various -

chemistry issues.

Based upon the information uncovered to date, as well as the conclusions drawn by EOl and

. outside consultants, EOl has determined that the most probable cause of the fuel cladding perforations was a result of " thermally-induced accelerated corrosion, due to the combined effects of elevated iron and copper deposits with a chemistry excursion early in the operating cycle." ' Consequently, EOl has decided to undertake the following actions:

1.

Remove all once-burned fuel assemblies from the HGE batch; 2.

Redesign the reactor core to accommodate a new reload batch for Cycle 9; 3.

Change the RBS chemistry program to (a) reduce metals transport to the reactor, (b) improve chemistry monitoring capability, and (c) increase chemistry monitoring; 4.

Cycle 9 will operate as a "short cycle" (approximately half of the normal 18-month operating cycle); and

5. ' RBS will perform confirmatory inspection during the ninth refueling outage.

The public portion of the meeting was concluded and members of the public were given the opportunity to provide comments to the NRC staff. A copy of the slides used during the public, nonproprietary session are provided as Enclosure 2. The meeting reconvened with a briefing on additional details, including information requested by EOl to be considered proprietary under Title 10 of the Code of Federal Reaulations, Section 2.790. The briefing included presentations by EOl and GE.

ORIG. SIGNED BY Robert Ji Fretz, Project Manager, Section 1 Project Directorate IV & Decommissioning Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-458 DISTRIBUTION

~ Docket File OGC

Enclosures:

PUBLIC ACRS

1. List of Meeting Attendees PDIV-1 RF -

G. Hill (4)

2. EOl Slide Presentation S. Richards K. Brockman, RIV R. Gramm J. Zwolinski/S. Black cc w/encis: See next page R.Fretz Meeting Attendees Document Name: G:\\PDIV-1\\RiverBend\\MtgSummary NRC-EOl 062299,wpd j

To receive co y of document indicate - E = copy w/onci c = copy w/o enci N = no copy l

OFFICE PM/PDIV 1 ' nE LA/PDIV 'i

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NAME RFretz:db LBerry hh krkm DATE 7 / 7], /99 h/

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OFFICIAL RECORD COPY