ML20117F726

Provides Info on Actions Taken During McGuire Unit 2 Current Refueling Outage (2EOC10) in Response to NRC Bulletin 96-001.Facility Control Rod Drive Line Performance Evaluation Analysis Encl

ML20117F726
Person / Time
Site:	Mcguire
Issue date:	05/13/1996
From:	Mcmeekin T DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
IEB-96-001, IEB-96-1, NUDOCS 9605200096
Download: ML20117F726 (8)

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' DukcibwerCompany T. C klctitim

- hicGuire Nuclear Generation Department Vice President 12700Hagers FerryRoad(AIG01W) (704)8754800 Huntersville, NC280784985 (704)8754809 Fax 7-~5 -

DUKEPOWER (v ~ )

May_13, 1996 U. S. Nuclear Regulatory Commission Attention: Documen*. Control Desk washington, D.C. 20555

SUBJECT:

Duke Power Company McGuire Nuclear Station - Unit 2 Docket No. 50-370 NRC Bulletin 96 Outage Test Data The purpose of this letter is to provice information on McGuire Unit 2 actions taken during the current refueling outage (2EOC10) in response to NRC Bulletin 96-01.

NRC Bulletin 96-01, dated March 8, 1996, requested holders of operating licenses for Westinghouse designed plants to take actions and supply 4 information to the NRC regarding recent control rod insertion problems. l The initial Duke Power response to this bulletin was provided by letter dated April 4, 1996 and supplemented with additional information by letter dated April 30, 1996.

Restated below are pertinent sections of NRC Bulletin 96-01 requiring actions during the current McGuire Unit 2 refueling outage:

Requested Action (3):

(3) Measure and evaluate at each outage of sufficient duration during calendar year 1996 (end of cycle, maintenance, etc.), the control rod drop times and rod recoil data for all control rods. If appropriate plant conditions exist where the vessel head is removed, measure and evaluate drag forces for all rodded fuel assemblies,

a. Rods failing to meet the rod drop time in technical specifications shall be deened inoperable,

b. Rods failing to bottom or exhibiting high drag forces shall require prompt corrective action in accordance with Appendix B to Part 50 of Title 10 of the Code of Federal Regulations (10 CFR Part 50).

Required Response Item (3):

(3) Within 30 days after completing Requested Action (3) for each outage, a report that summarizes the data and that documents the results obtained; this is also applicable to Requested Action (4)when any abnormal rod behavior is observed.

1 000GM ,

9605200096 960513 PDR ADOCK 05000370 G PDR (

1 U. S.' Nuclear Regulatory Commission.

Document' Control Desk '

Hay 13, 1996' .

I Page 2/3 McGuire Response to Item (3):

i Included as. Attachment 1 and 2 to this letter is a summary report of the l McGuire Unit 2 data for Requested Action (3) obtained during testing 1 performed in conjunction with the Unit 2 End-of-Cycle.10 refueling ,

outage. This testing was completed on April 12, 1996.

Further testing will.be performed _in'accordance with the requested information within the NRC Bulletin. i

.Please direct questions on this matter to James E. Snyder at

(704) 875-4447.  ;

Very truly yours,  ;

I T. C. McHeekin i l

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U. S. Nuclear Rrgulatory Commission Document Cont'.ol Desk May 13, 1996 Page 3/3 l

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! Attachzrent 1 1

McGuire Unit 2 Control Rod Drive Line Performance Evaluation Analysis Attachment 2 McGuire Unit 2 RCCA Drag Test Before Fuel Unload cc: Mr. S D. Ebneter, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta St., NW, Suite 2900 Atlanta, GA 30323 l Mr. Victor Nerses U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, D.C. 20555 i

Mr. George Maxwell NRC Resident Inspector McGuire Nuclear Station l

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c McGuire Nuclear Station

, NRC Bulletin 96-01 l

' Attachment 1 Unit 2 Control Rod Drive Line l Performance Evaluation Analysis l

• i on April 5, 1996 Control Rod Drop Timing was performed in accordance with requirements of NRC Bulletin 96-01. The following is a summary of the data analysis of the Control Rod Drive Line Performance Evaluation for McGuire Nuclear Station Unit 2.

During the Unit 2 EOC10(End of Cycle) outage, Rod Drop Testing was performed on the Drive Lines. This included a detailed analysis of Control Rod Drop Times (see attached data tables). .

McGuire Nuclear Station has trended control rod drop times from initial plant startup in 1983. The data has been consistent during all testing r on Unit 1 and 2.

The analysis method used consisted of a detailed review of each control rod's time based profile. Four rods, F-10, H-08,.H-10 and N-09, were flagged as having slightly longer drop times. All four of these control rods were still well within their required time. The profiles of eight rods were then superimposed on each other and compared. The mean '

profile was used to compare an additional seven rods. This process was repeated until all of the rods were analyzed. Again the same four -

control rods exhibited a slight variance in their profiles.

McGuire traces did not reveal any change at the top of the fuel  !

assembly. However, four of the McGuire traces indicated a very slight j change at the center of the fuel assembly. Duke Power's analysis of [

industry data indicates that this is typical of the majority of rods  !

throughout the industry that use Westinghouse fuel. This typical >

category is a deceleration prior to the Dashpot Region. ,

Duke Power has detailed information on the testing and analysis I methodology and is willing to share with the NRC upon request.

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! McGuire Nuclear Station NRC Bulletin 96-01 Attachment 2 Unit 2 EOC-10 RCCA Drag Test Before Fuel Unload April 18, 1996 The McGuire Unit 2 RCCA (Rod Cluster Control Assembly or control rod) drag test was conducted in conjunction with heavy drive rod >

unlatching. Drive rod unlatching takes place before the initial ,

removal of the upper internals. The Unit 2 control rod drag test before fuel unload was performed in response to McGuire L Evaluation of NRC Bulletin 96-01, Control Rod Insertion Problems The purpose of the drag test is to address an industry issue of some control rods not fully inserting into the dashpot region during a reactor scram. The dashpot is the lower l one and a half feet of a fuel assembly guide thimbles. A control rod is connected to a drive rod which is then lifted, lowered, or released by a CRDM (Control Rod Drive Mechanism).  !

l The control rod drag test took place April 11- 12, 1996.

During a control rod drag test, the weight will gradually increase or decrease as the control rod is raised or lowered.

The reference weight of 923 pounds is the average load cell reading with the control rod raised six (6) inches and at rest.

Because of buoyancy effects, the gradual weight change during a normal drag test is from 923 pounds to 965 pounds after 10 feet of travel.

The control rod drag test arrangement consists.of a digital load cell attached to the manipulator crane auxiliary hoist. The l load cell is attached to the. lifting bail of the unlatching tool. The unlatching tool is then attached to each drive rod.

The recorded weights in Tables 1 and 2 are from visual observations of a digital load cell. Table 3 is a summary of the dashpot drag loads during withdrawal and insertion.

During control rod withdrawal drag tests, all control rods were within the Westinghouse F-Spec No. 7.1 tolerance of plus or minus 100 pounds (Table 1). The greatest weight delta of 71 I pounds occurred on core locations H-8 and N-9 followed by H-10 l l at 69 pounds and C-9 at 59 pounds. Three of these locations  !

l correspond to those locations with the longest drop times noted j in Attachment #1. Both the rod drop times and the drag test data were within acceptable criteria.

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4 McGuire Nuclear Station NRC 13ulletin 96-01 Attachment 2 Page 2/4 Table 1 - Maximum Dash Pot Withdrawal Weights During Control Rod Drag Test Reference weight: 923 pounds Control Maximum Control Maximum Control Maximum Rod Core Dashpot Rod Core Dashpot Rod Core Dashpot Location Weight Location Weight Location Weight Reading Reading Reading (Pounds) (Pounds) (Pounds)

B-4 932 F-8 962 K-14 930 B-6 922 F-10 974 L-3 944 B-8 930 F-14 944 L-13 932 B-10 930 G-3 966 M-2 936 B-12 960 G-13 962 M-4 934 C-5 942 H-2 938 M-8 940 C-7 944 H-4 960 M-12 935 C-9 982 H-6 958 M14 935 C-11 956 H-8 994 N-5 934 D-2 930 H-10 992 N-7 944 D-4 948 H-2 950 N-9 994 D-8 938 H-14 924 N-11 950 D-12 972 J-3 956 P-4 946 D-14 936 J-13 936 P-6 930 E-3 946 K-2 938 P-8 942 E-13 970 K-6 964 P-10 934 F-2 930 K-8 948 P-12 942 F-6 962 K-10 974 Average 948 Wt.

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. e McGuire Nuclear Station NRC Bulletin 96-01 Attachment 2 Page 3/4 Table 2 - Minimum Dash Pot Insertion Weight During Control Rod Drag Test Reference Weight: 923 pounds Control Minimum Control Minimum Control Minimum Rod Core Dashpot Rod Core Dashpot Rod Core Dashpot Location Weight Location Weight Location Weight Reading Reading Reading (Pounds) (Pounds) (Pounds)

B-4 900 F-8 874 K-14 900 B-6 904 F-10 858 L-3 886 B-8 902 F-14 882 L-13 900 B-10 894 G-3

• M-2 894 B-12 868 G-13 870 M-4 892 C-5 892 H-2 850 M-8 890 C-7 886 H-4 882 M-12 900 C-9 850 H-6 874 M14 886 C-11 874 H-8 844 N-5 898 D-2 900 H-10 842 N-7 894 D-4 888 H-12 842 N-9 840 D-8 896 H-14 884 N-11 884 D-12 864 J-3 890 P-4 898 D-14 896 J-13 896 P-6 898 ,

E-3 880 K-2 884 P-8 888 l E-13 862 K-6 886 P-10 888 I F-2 856 K-8 886 P-12 890 F-6 872 K-10 862 Average 880 Wt. i

• Invalid data was obtained for position G-3 due to a recording l error. Location G-3 showed no drop time anomaly.

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McGuire Nuclear Station

• NRC Bulletin 96-01 s Attachment 2 -

Page 4/4 Table 3 - Withdrawal and Insertion rashpot Weight Differences from the Reference Weight I

Control Withdra Insertion Control lWithdra Insertion Control Withdra Insertion Rod Core wal Weight Rod Core  ;;al Weight Rod Core wal Weight Location Weight Delta Location Weight Delta Location Weight Delta Delta (Pounds) Delta (Pounds) Delta (Pounds)

(Pounds (Pounds (Pounds

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B-4 9 23 P-8 39 49 K-14 7 23 B-6 0 19 F-10 51 65 L-3 21 37 B-8 7 21 F-14 21 41 L-13 9 23 B-10 7 25 G-3 43

• M-2 13 29 B-12 37 55 G-13 39 53 M-4 11 31 C-5 19 31 H-2 15 73 M-8 17 33 C-7 21 37 H-4 37 41 M-12 12 23 C-9 59 73 H-6 35 49 M14 12 37 C-11 33 49 H-8 71 79 N-5 11 25 D-2 7 23 H-10 69 81 N-7 21 29 D-4 25 35 H-12 27 81 N-9 71 83 D-8 15 27 H-14 1 39 N-ll 27 39 D-12 49 59 J-3 33 33 P-4 23 25 D-14 13 27 J-13 13 27 P-6 7 25 E-3 23 43 K-2 15 39 P-8 19 35 E-13 47 61 K-6 41 37 P-10 11 35 F-2 7 67 K-8 25 37 P-12 19 33 F-6 39 51 K-10 51 61

• Invalid data was obtained for position G-3 due to a recording error. Location G-3 showed no drop time anomaly.

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