ML20101Q295

Forwards 30-day Response to NRC Bulletin 96-001, Control Rod Insertion Problems

ML20101Q295
Person / Time
Site:	Farley
Issue date:	04/04/1996
From:	Dennis Morey SOUTHERN NUCLEAR OPERATING CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
IEB-96-001, IEB-96-1, NUDOCS 9604110107
Download: ML20101Q295 (11)

Text

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Southrrn Nucl:ar Op; rating Company Post Offica Box 1295 Birmingham. Alabama 35201 T& phons (205) 868 5131 k

L Southern Nudear Operating Company Dave Morey Vice President Farley Project April 4,1996 The Southern eleCfDC System Docket Nos.: 50-348 10 CFR 50.54 50-364 U. S. Nuclear Regulatory Commission ATTN: Document Contro.' Desk Washington, D. C. 20555-0001 Joseph M. Farley Nuclear Plant 30-Day Response to NRC Bulletin 96-01 Control Rod Insertion Problems Ladies and Gentlemen:

By letter dated March 8,1996, the NRC issued Bulletin 96-01, " Control Rod Insertion Problems," requiring actions to be taken by utilities regarding the susceptibility and evaluation of the Rod Control System to the phenomena of control rod failure to completely insert. The Bulletin was issued to accomplish two goals; first, to alert addressees to problems encountered during recent events in which control rods failed to completely insert upon the scram signal, and second, to assess the operability of control rods, particularly in high burnup fuel assemblies. The Bulletin requested licensees provide a 30-day response which assesses the operability of the control rods.

Provided in Attachments 1 and 2 is the Southern Nuclear Operating Company (SNC) 30-day response for the Farley Nuclear Plant (FNP). Southern Nuclear Operating Company considers that the control rods for both units are operable based on a review of plant specific data and current industry data as noted in our enclosed response. Should you have any questions, please advise.

9604110107 960404 PDR ADOCK 05000348 Respectfully submitted, O

PDR 110023 f f ?/ h Dave Morey' Sworn to andsubscribedb fore me this hday of 0Y 1996

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My Commission i s WAS/ cit:bul_,9601. doc Attachments l

cc:

Mr. S. D. Ebneter, Region II Administrator Mr. B. L. Siegel, NRR Senior Project Manager 7

l Mr. T. M. Ross, FNP Sr. Resident Inspector I

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ATTACHMENT 1 i

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SNC RESPONSE l

NRC Reauired Resnonse (1)

Within 30 days of the date of this bulletin, a report certifying that control rods are determined to be operable; actions taken for Requested Actions (1) and (2); and the plans l

for implementing Requested Action (3) and (4).

SNC Response:

l Requested Action (1) l Promptly inform operators of recent events (reactor trips and testing) in which control rods did not fully insert and subsequently provide necessary training, including simulator drills, uti'izing the required procedures for responding to an event in which l

the control rods do not fully insert upon reactor trip (e.g., boration of a pre-specified amount).

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SNC Response:

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All licensed personnel assigned to on-shift duties have been notified of the recent l

industry events, the potential impact to FNP should such an event occur there, and the proper compensatory actions to take in the event of such an event. Simulator time is being provided for the operating crews during the requalification cycle now in progress.

i During this session the crews will observe an event similar to that addressed by the j

bulletin and training on procedures to be used for addressing the event will be re-i emphasized. This trainind as been incorporated in the 1996 License Requalification h

Program and will be competed by May 1,1996, for appropriate individuals.

Requested Action (2)

Promptly determine the continued operability of control rods based on current information. As new information becomes available from plant rod drop tests and trips, licensees should consider this new information together with data already available from Wolf Creek, South Texas, North Anna, and other industry experience, and make a prompt determination of control rod operability.

SNC Responst The FNP control rods are operable. Proper rod movement has been verified by periodic rod stepping during power operation as required by Technical Specifications.

There have been no instances of rods failing to fully insert after a trip for FNP Units 1 or 2. In addition, recorded rod drop times and rod stepping tests show no indications l

of control rod sticking.

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i SNC Response At FNP, a standard 12-foot active fuel lcrgth core design is used on both units which consists ofLOPAR and/or Vantage 5 fuel. A review of burnup data for FNP rodded assemblies was performed to determine the highest burnup in a rodded assembly during l

near end of cycle reactor trips since Vantage 5 fael has been in the core. Burnups in excess of 41,800 MWD /MTU in Vantage 5 tuel and 52,300 MWD /MTU in LOPAR fuel were present during the trips with no instances of a failure of a control rod to insert.

l A review of drag testing performed on rodded fuel assemblies since Vantage 5 fuel has been used at FNP indicated no instances of abnormal or excessive drag.

l As ofFebruary 29,19N, all fuel assemblies which house control rod assemblies on both FNP units had burnups which were le s than 43,000 MWD /MTU. The maximum j

l estimated burnup at EOL of any assembly currently in service which houses a control rod assembly is less than 49,000 MWD /MTU.

Both Farley Unit 1, Cycle 14 and Unit 2, Cycle 11 have shutdown margin in excess of I

the minimum required by Technical Specification 3.1.1.1 (which accounts for the most j

reactive control rod stuck fully withdrawn from the core).

Additional industry data has been compiled by the WOG. This information indicates that for data on 24 plants received thus far, 501 rodded assemblies had accumulated burnup greater than 40 MWD /MTU and 106 rodded assemblies had accumulated burnup greater than 45 MWD /MTU (the large numbers of fuel assemblies are based upon receiving data from multiple cycles over up to a five year period). None of these plants reported problems with control rod insertion. FNP will continue to follow this issue with the industry.

i Rgquested Action (3) l Measure and evaluate at each outage of sufficient duration during calendar year 1996 l

(end of cycle, maintenance, etc.), the control rod drop times and rod recoil data for all i

control rods. If appropriate plant conditions exist where the vessel head is removed, l

measure and evaluate drag forces for all rodded fuel assemblies,

a. Rods failing to meet the rod drop time in the technical specifications shall be deemed 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).

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SNC Response 1

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SNC Response:

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For FNP Units 1 and 2, the following actions will be performed:

If a planned or unplanned shutdown of sufficient length occurs in 1996, the unit e

i will be tripped prior to completely driving the rods in. Rod insertion will be observed and hot rod drop time testing with rod recoil measurement will be performed for the first shutdown on a unit only, unless timely complete rod insertion does not occur.

If the unit trips in 1996, timely rod insertion will be confirmed. If timely rod l

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insertion is not observed, hot rod drop testing with rod recoil measurement will be performed.

For the Unit 2, Fall 1996 Refueling Outage:

e The unit will be ramped down and tripped prior to completely driving the rods in. Rod insertion will be observed.

l Hot rod drop time testing with rod recoil measurement will be performed prior

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i to cooling down.

Control rod drag testing will be performed in either the reactor vessel prior to core offload or in the spent fuel pool after offload.

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Rod drop time testing with rod recoil measurement will be performed when coming out of the outage.

l No further testing is planned to be performed on the unit after the scheduled l

outage due to low burnup.

Reauested Action (4)

For each reactor trip during calendar year 1996, verify that all control rods have promptly fully insened (bottomed) and obtain other available information to assess the operability and any performance trend of the rods. In the event that all rods do not fully insert promptly, conduct tests to measure and evaluate rod drop times and rod recoil.

SNC Resoonse:

If either unit trips in 1996, timely rod insertion will be confirmed. If timely rod insertion is not observed, hot rod drop time testing with rod recoil measurement will be performed.

NRC Reauired Response (2)

I Within 30 days of the date of this bulletin, a core map of rodded fuel assemblies indicating i

fuel type (materials, grids, spacers, guide tube inner diameter) and current and projected end of cycle burnup of each rodded assembly for the current cycle; when available, proside the same information for the next cycle.

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SNC Response SNC Response:

The requested information is provided for the current fuel cycles in Attaciunent 2. The information in Attachment 2 is organized as follows for each unit: a core map indicating for each rodded location the control rod bank identification, the assembly identification number, the burnup as of February 29,1996, and the projected end of cycle burnup. In addition, a table of the physical assembly characteristics of the regions of fuel which contain control rods.

i The requested information for the next cycle for each unit is not currently available, as those designs are not finalized and are still subject to change. The requested information l

will be provided for the next cycle on each unit within 30 days following the initial enticality of that cycle.

NRC Reauired Response (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.

SNC Response:

To be submitted when required by the above evaluations performed in 1996.

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4 ATTACHMENT 2

PHYSICAL CHARACTERISTICS OF RODDED ASSEMBLIES PLANT FARLEY UNIT 1 CYCLE 14 REGION 2E REGION 2F Assembly Type Vantage-5*

Vantage-5*

Clad Material Ziro 4 Zirc-4 Grid Matedal Mid-span grids Zirc4 Zirc-4 Bottom / Top grid inconel-718 inconel-718 Guide Tube Material Zirc-4 Zirc-4 Guide Tube O.D. (inches)

Above dashpot 0.4740 0.4740 At dashpot 0.4300 0.4300 Guide Tube I.D. (inches)

Above dashpot 0.4420 0.4420 At dashpot 0.3970 0.3970

• 17x17 assemblies with optimized fuel rod O.D. of 0.360 in, and with intermediate flow mixing (lFM) grids

PHYSICAL CHARACTERISTICS OF RODDED ASSEMBLIES PLANT FARLEY UNIT 2 CYCLE 11 REGION W REGION 2M REGION 2N Assembly Type LOPARW Vantage-5W Vantage-5W Clad Material Zirc-4 Zirc-4 Zirc-4W Grid Material Mid-span grids Inconel-718 Ziro-4 Zirc.4 Bottom / Top grid Inconel-718 Inconel-718 Inconel-718 Guide Tube Material Zirc-4 Ziro-4 Zirc-4 Guide Tube O.D. (inches)

Above dashpot 0.4820 0.4740 0.4740 At dashpot 0.4300 0.4300 0.4300 i

Guide Tube 1.D. (inches)

Above dashpot 0.4500 0.4420 0.4420 At dashpot 0.3970 0.3970 0.3970 (1) 17x17 assemblies with standard fuel rod O.D. of 0.374 in without intermediate flow mixing (IFM) grids.

(2) 17x17 assemblies with optimized fuel rod O.D. of 0.360 in. and with intermediate flow mixing (IFM) grids.

(3)

Two assemblies (2N41 and 2N52) each contain 12 ZlRLO clad fuel rods for demonstration.

Farley Unit 1 Cycle 14 R

P N

M L

K J

H G

F E

D C

B A

1 1

A U

A 2E08 2F22 2E03 24243 4609 24390 i

l 33559 21707 33600 bk bk 2F02 2F04 5799 5803 25818 25840 b

b b

b 2E50 2ES$

2E59 2E49 i

25393 30660 30882 25032 38365 48368 48398 31365 SB 5t$

2E20 2E26 32665 32645

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48792 48792

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k 5

U b

b D

k 2E06 2E55 2E25 2F36 2E32 2E57 2E05 24496 31100 31782 5940 31661 30925 24096 33500 48398 47241 26564 47241 48366 33559 l

5A 5tS 35 5A 2F05 2F53 2F54 2F06

$958 5801 5704 5823 25840 258N 25894 25818 D

G U

U 2F21 2F46 2F43 2F32 I

4484 6050

$N5 4806 21707 26564 26564 21707 SA su su 5A 2F07 2F55 2F56 2F01 5973 5825 5765 5869 25818 258M 258N 25648 A

R$

U U

O ES A

2E01 2EG1 2E18 2F39 2E33 2E54 2E07 24631 38619 31909 403s 31844 3.053 24392 33559 48388 47241 26564 47241 48398 33800 bb 35 2E28 2E30 32722 32932 48792 48792 b

U b

U b

2E51 2E40 2E54 2E46 25222 31186 31232 25070 38365 4 398 4:368 38345 14 5A 5A 2F08 2F03 6000 8040 25640 25818 1

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LEGEND 4E

- ROD BANK 241 o 24481

-ASSY. NUMBER 33800 21797 335st

-CURR.BURNUP'

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Farley Unit 2 Cycle 11 R

P N

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H G

F E

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B A

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A U

A W48 2N44

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42444 12469 42339 47103 24280 47086 3

2M56 2M57 32139 32381 42662 42883 b

b b

b 2N01 2M33 2M10 2N02 1146g 35523 35308 11408 21889 45263 45358 21871 55 35 2M12 2M24 35344 35430 44900 44933 A

u U

b U

n A

W33 2M3s 2M07 2M34 2M02 2M26 W40 42139 35663 34650 36083 33975 35115 42204 47081 45378 44158 45871 44121 45271 47087 5A su du 5A 2M42 2M45 2M44 2MGO 32657 31143 31909 32296 42849 41698 42048 42765 D

G G

U 2N41 2M15 2M09 2N52 12541 35600 35712 12278 24211 45820 45800 24210 SA sB sB sA 2M49 2M47 2M50 2M41 i

32171 31589 31826 32249 42764 42007 42072 42060 A

5 U

U U

U A

Wei 2M25 2M03 2M13 2M06 2M14 W34 42187 35531 34317 35406 33721 35231 41901 47075 45270 44128 45924 44145 4g374 47090 35 55 2M29 2M32 35214 35301 44931 44938 U

U D

b 2NO3 2M38 2N21 2N04 11454 35294 35029 11421 21871 45342 46212 21876 14 sa sa 2M55 2M48 32314 32570 1

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155 M

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-ASSY. NUMBER 47093 24247 47081

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