ML20137X413

Summary of 970110 Meeting W/W in Rockville,Md to Discuss Incomplete Rod Cluster Control Assemblies Insertions.List of Attendees & Matl Used in Presentation Encl

ML20137X413
Person / Time
Issue date:	04/16/1997
From:	Craig C NRC (Affiliation Not Assigned)
To:	Matthews D NRC (Affiliation Not Assigned)
References
NUDOCS 9704220022
Download: ML20137X413 (42)

Text

April 16, 1997' MEMORANDUM TO: David B. Matthews, Chief

' Generic Issues and Environmental Projects Branch Division of Reactor Program Management Office of Nuclear Reactor Regulation FROM:

Claudia M. Craig, Senior Project Manager Original Signed By:

Generic Issues and Environmental Projects Branch.

Division of Reactor Program Management Office of Nuclear Reactor Regulation

SUMMARY

OF MEETING WITH WESTINGHOUSE TO DISCUSS INCOMPLETE ROD CLUSTER CONTROL ASSEMBLIES (RCCA) INSERTIONS The' subject meeting was held at the Nuclear Regulatory Commission (NRC) offices in Rockville, Maryland on January 10, 1997, between representatives of Westinghouse and the NRC staff. The purpose of the meeting was for Westinghouse to provide an update of the RCCA insertion test data, provide a comparison of 14 foot fuel versus 12 foot fuel and their susceptibility to incomplete RCCA insertions, discuss the impact of intermediate flow mixing grids (IFMs) and ZIRLO, provide.burnup guidance developed by. Westinghouse, and provide preliminary design changes. Attachment 1 is a list of meeting participants.

By letter dated January 16,.1997, the proprietary and non-proprietary versions of the presentation daterial were submitted. ~ Attachment 2 is a copy of the non-proprietary version of the presentation material.

Westinghouse provided a summary of the testing performed to date and the different parameters that were examined, in addition to testing results which led them to develop-the root cause. Westinghouse discussed their short term-corrective action, but recognizes that long-term solutions are needed.

Westinghouse outlined their draft process to address acceptability when plants exceed the recommended values. The process includes a two prong approach:

first, a safety evaluation needs to be performed to determine shutdown margin

.and second, a prediction of the acceptability of the future fuel assembly bowing needs to be determined.

This will-be accomplished using the mechanical model which has been developed. Westinghouse requested a meeting be set up in the future to discuss the mechanical model and the acceptability process.

The final RCCA insertion issue root ~ cause report is scheduled to be submitted to the staff in mid to late February 1997.

Attachments: As stated cc w/atts: See next page DISTRIBUTION:See attached page DOCUMENT NAME:

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NUCLEAR REGULATORY COMMISSION j

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'I WASHINGTON, D.C. Snaan anni April 16, 1997 4

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MEMORANDUM TO: David B. Matthews, Chief Generic Issues and Environmental s

i Projects Branch Division of Reactor Program Management 1

Office of Nuclear Reactor Regulation FROM:

Claudia M. Craig, Senior Project Manager h

AIUC Generic Issues and Environmental Projects Branch b

i i

Division of Reactor Program Management-Office of Nuclear Reactor Regulation

SUMMARY

OF MEETING WITH WESTINGHOUSE TO DISCUSS INCOMPLETE ROD CLUSTER CONTROL ASSEMBLIES (RCCA) INSERTIONS l

The subject meeting was held at the Nuclear Regulatory Commission (NRC) offices in Rockville, Maryland on January 10, 1997, between representatives of Westinghouse and the NRC staff. The purpose of the meeting was for Westinghouse to provide an~ update of the RCCA insertion test data, provide a comparison.of 14 foot fuel versus,12 foot fuel and their susceptibility to incomplete RCCA insertions, discuss the impact of intermediate flow mixing grids (IFMs) and ZIRLO, provide burnup guidance developed by Westinghouse, and provide preliminary design changes. Attachment 1 is a list of meeting participants.

By letter dated January 16, 1997, the proprietary and non-proprietary versions of the presentation material were submitted. Attachment 2 is a copy of the non-proprietary version of the presentation material.

Westinghouse provided a summary of the testing performed to date and the different parameters that were examined, in addition to testing results which led them to develop the root cause. Westinghouse discussed their short term corrective action,'but recrgnizes_ that long-term solutions are needed.

Westinghouse cutlined their draft process to address acceptability when plants i

exceed the recommended values. The process includes a two prong approach:

first, a safety evaluation needs to be performed to determine shutdown margin and second, a prediction of the acceptability of the future fuel assembly bewing needs to be determined. This will be accomplished using the mechanical model which has been developed. Westinghouse requested a meeting be set up in the future to discuss the mechanical model and the acceptability process.

The final RCCA insertion issue root cause report is scheduled to be submitted to the staff in mid to late February 1997.

Attachments: As stated l

cc w/atts: See next page

WESTINGHOUSE / NRC MEETING INCOMPLETE RCCA INSERTION UPDATE JANUARY 10, 1997 MEETING PARTICIPANTS HaME ORGANIZATION Claudia Craig NRC/NRR/PGEB Harold H. Scott NRC/RES Kenneth Turnage Southern Nuclear l

Ernie Kee HL&P - South Texas i

Satoshi Azumi Kansai Electric Power i

Lynn Connor for STS J. Rajan NRC/NRR/EMEB Robert Hinkle Northeast Utilities Gerald Canavan

'New York Power Authority H. Oley Nelson Northern States Power Kris Thomas NRC/NRR PDIV-2 Vance VanderBurg AEP and WOG Roger Newton WEPCo/WOG Jim Sparrow Westinghouse CNFD Howard Menke Westinghouse CNFD j

Sumit Ray Westinghouse CNFD j

Nick Liparulo Westinghouse NFD 1

Brian Sheron NRC/NRR/ADT 5

Jim Lyons NRC/NRR/SRXB Muffet Chatterton NRC/NRR/SRXB Dick Wessman NRC/NRR/EMEB Henry Sepp Westinghouse Vincent J. Esposito Westinghouse CNFD a

ATTACHMENT 1

I DISTf:It10 TION w/ attachments: Sumnery of January 1016. 1997, 1997, with Westinghouse dated April

' Central File PljBLIC

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PGEB R/F RArchitzel CCraig 1

E-Mail I

Sco111ns/FMiraglia TMartin RZDimerman

'GHolahan BSharon EWeiss MChatterton i'3cott

. JRa.ian C.h sman Kihomas 1H0rnstein JLyons

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L Incomplete RCCA Insertion Summary Update i

NRC Meeting 1/10/97 1

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Incomplete RCCA Insertion i

Purpose of Meeting l

r Provide update of recent data, focus on why 14 ft. fuel behaves differently than 12 ft. fuel, impact ofIFM/ZIRLO, burnup guideline and design changes to increase margins for extended burnup i

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i Incomplete RCCA Insertion Agenda t

Accumulated Test Data 1

Summary of Wolf Creek Root Cause 14 Ft. Fuel versus 12 Ft. Fuel

)

Special Featured Fuel Assemblies Safety Significance Core Loading Pattern Process j

Potential Design Changes.

Conclusions / Summary j

i i

i Accumulated Test Data - Significant Amount of Data Obtained in 1996 s

96-01 Testing Root Cause

1. FA Inspections - 174 i

1. FA Rod Drop Tests (Total)- 2175

1. Plant Sites - 10 l

1. FA Rod Drop Tests (IFM)- 1031

1. FA Growth Measurements - 137

1. Drag Tests (Total)-- 1356

1. Drag Tests - 147 i

1. Drag Tests (IFM)- 586 i

1. Single Tube Probe Tests - 37

1. FA in Hot Cell - 2 i

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SUMMARY

OF PLANT TRIP INFORMATION 1

i Data From 50 Plants (Westinghouse & Non-Westinghouse Fuel) l j

Burnup of Assemblies Under RCCAs Full and Incomplete Insertion Comparison

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1800 3 ullInsenion F

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l Number FAs Showing i

BU (GWD/MTU) Range Number FAs Showing incomplete Insertion Under RCCAs Full insertion Wolf Creek So. Texas 1 27.5 - 32.5 1878 0

1 32.5 - 37.5 1444 0

1 37.5 - 42.5 1199 0

0 i

42.5 47.5 575 0

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47.5 - 52.5 123 5

2 52.5 - 57.5 18 0

0 57.5 - 62.5 1

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TOTAL 5238 5

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O Summary of 96-01 Rod Drop Testing (Westinghouse Fuel) 450 3M 400 u)

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6-t ROOT CAUSE INVESTIGATION i

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i Accumulated Test Data:

Key Observations t

No unusual FA growth for 12 ft. W fuel except Wolf Creek Normal FA growth noted for 14 ft. W fuel No incomplete insertion without unusual growth in 12 ft. fuel Incomplete insertion for 12 ft. W fuel shows high drag in both dashpot and thimble tube Many FAs operating at high burnup levels without insertion problems acta esp &ac ppt 8/6N7

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'I Accumulated Test Data Major Parameters FA Parameters

- Holddown spring force j

- Skeleton material j

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- Dashpot design

- IFMs Operational Parameters

- Burnup i

- Core temperature l

- Power history j

- Residence time i

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i, ROOT CAUSE DETERMINATION PROCESS i

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l Summary of Wolf Creek Root l

Cause Incomplete RCCA insertion caused by high

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compressive loads on FA thimble tubes i

Unusual FA growth contributed to high j

l compressive loads Growth due to corrosion and accelerated growth j

of thimb3e tubes (temperature sensitive) j Unusual growth requires high temperature, high burnup with 3 cycle residence time / power histories l

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14 Ft. vs 12 Ft. Core Differences

• Dashpot Design: Double vs Single Key Critical Features:

Assembly Weight Length Holddown Force Hydraulic Lift Force Typical Span Length Dashpot Length Number of Transitions (1 vs 3)

Compressive loads in dashpot region approximately twice those of 12 ft. core

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14 Ft. vs 12 Ft. Core Differences i

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I 14 ft. Behavior 1

- Dashpot bow is [

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- Field data for incomplete insertion shows FA growth is l

not excessive or unusual

- Distortion in dashpot region can be [

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14 Ft. Core vs 12 Ft. Core Differences (continued)

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1 Basic reasons why 14 ft. fuel is more susceptible than 12 ft. core-i

- Dashpot design enhances distortion due to [.

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- Higher compressive loads in dashpot Root cause: High compressive loads and dashpot design i

Exceeding F-spec criteria and tie to unusual growth j

does not hold for 14 ft. due to dashpot design

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-l Special W Fuel Assembly Features IFMs i

- Data shows lower drag in upper guide tube which ensures entry of control rod into dashpot (no safety l

issue)

- Some data shows high dashpot drag but insertion still achieved i

- In no case are both F-spec criteria exceeded, no insertion problem esta up&ac ppe inv97

Figure 1 - Summary of RCCA insertion information - lFM Fuel

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Special W Fuel Assembly Features IFMs

- IFM FAs are less susceptible than non-IFM FAs Reduced drag in upper guide tube region due to increased stiffness t

Reduced compressive loads due to increased AP from IFM grids j

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Special W Fuel Assembly Features IFM Conclusions i

No reported incomplete insertion for IFMs 1

Drag tests with IFM do not exceed F-Spec Mechanical model predicts lower thimble tube bow for IFM FA than Wolf Creek H50 i

No Restrictions on IFMs up to Current i

Burnup Limit

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I Special W Fuel Assembly Features ZlRLO

- Basic material property differences between ZIRLO and Zirc-4 are significant relative to RCCAs Growth rate vs burnup Fuel rod growth vs burnup Creep rate [

]*6c Oxide data

- Comparison of Wolf Creek 50H FA with and w/o ZIRLO Span bow [

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i Special W Fuel Assembly Features: IFMs and ZIRLO (continued) i

- ZIRLO skeletons are significantly less susceptible than Zirc-4 skeletons due to material properties such as [

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- Additional high burnup data will be available from demos j

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- ZIRLO skeletons require no burnup restrictions l

given current burnup license limit

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f Recommendation for Current Operating W Cores j

= No restriction for IFM or ZIRLO skeleton FAs No restriction for low temperature plant or 2 cycle FAs i

Temperature > 615'F and 3 cycle FA (18 months) 12 Foot - 40,000 MWD /MWT 14 Foot - 30,000 MWD /MWT

= Temperature < 615'F 12 Foot - no restrictions

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= Process to assess acceptability should the above values be exceeded l

Process to Address Acceptability for Operating Plant above W Recommended Values abe i

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• a Potential Design Changes to Provide Additional Margin for Extended Burnup I

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I Conclusions Significant amount of data obtained and used to i

understand behavior A~ mechanical model has been developed to 1

predict span bow / growth A process under development to assess incomplete insertion No restrictions required for IFM and /or ZIRLO FAs based on current burnup licensing limit Design changes being pursued to eliminate issue and provide additional margin for the future

SUMMARY

i Bottom Line i

We will make this issue go away.

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Schedule ofNear-Term Actions i

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• Response to NRC Questions 1/17

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IFM Report to NRC 1/18 i

Final Root Cause Report 2/17.

Detail Technical Meeting TBD Identify Design Changes for 17 XL 4/97 Ship Modified 17 XL Assernblies 8/97 ru:a ign&se pre Iaww7

S cc:

0 Mr. Nicholas J. Liparulo Westinghouse Electric Corporation Mail Stop ECE 4-15 P.O. Box 355 Pittsburgh, PA 15230-0355 Mr. Henry A. Sepp Westinghouse Electric Corporation Mail Stop ECE 4-07A P.O. Box 355 Pittsburgh, PA 15230-0355 Mr. Andrew Drake, Project Manager Westinghouse Owners Group Mail Stop ECE 5-16 P.O. Box 355 Pittsburgh, PA 15230-0355 l