ML20092A563

Forwards Addl Info Re Spent Fuel Pool Rerack Mods,In Response to 840530 Telcon Request

ML20092A563
Person / Time
Site:	McGuire, Mcguire
Issue date:	06/11/1984
From:	Tucker H DUKE POWER CO.
To:	Adensam E, Harold Denton Office of Nuclear Reactor Regulation
References
TAC-53531, TAC-53532, NUDOCS 8406190263
Download: ML20092A563 (5)

Text

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DUKE POWER GOMPANY P.O. ISOx 33180 CIIAHLOTTE, N.O. 28242 B.

R TELEPHONE (7 4) a7a-mi

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June 11, 1984 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S._ Nuclear Regulatory Commission Washington, D. C. 20555 Attention:

Ms. E. G. Adensam, Chief Licensing Branch No. 4 Re: McGuire Nuclear Station

. Docket Nos. 50-369, 50-370

Dear Mr. Denton:

i As requested in a May 30, 1984 telephone conversation between Bernard Turovlin, NRC/0NRR, and W. H. McDowell, Duke Power Company, attached is additional in-formation concerning the McGuire spent fuel pool rerack modifications. If there are further questions regarding this matter,please contact us.

Very truly yours, W

_f:

Hal B. Tucker WHM:glb cc: Mr. James P. O'Reilly, Regional Administrator Mr. W. T. Orders U. S. Nuclear Regulatory Commission Senior Resident Inspector Region II McGuire Nuclear Station 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 i

9406190263 840611 PDR ADOCK 05000369 P

PDR

DUKE POWER COMPANY McGUIRE NUCLEAR STATION SPENT FUEL POOL RERACK MODIFICATIONS ADDITIONAL INFORMATION.

1...The following is a list of materials used in the spent fuel pools.

a.

Leveling pads - 1.5"' thick, type 304 S.S.

b.1 Leveling-pad' screw - 3.5" dia and 4.0" dia, type 304 S.S., chrome plated c.

. Leveling pad support plate - 3.5" thick and 4.5" thick, type 304 S.S.

d..

Base plate - 1/2" thick, type 304 S.S.

_ Cells - 0.075" thick, type 304 S.S.

e.

f.: ' Poison wrapper - 0.02" thick,. type 304 S.S.

.g..' Cover plate and filler' plate - 0.0747" thick, 304 S.S.

h.

Reinforcement Plate - 3.0" thick, type 304 S.S.

i. Box Beam - 0.109" thick, type 304 S.S.

J. _ Side Plate - 0.625". thick, type 304 S.S.

k.

Frame bar - 0.625" thick, type 304 S.S.

1.

Mock _ fuel assembly - 0.375" thick,' type 304 S.S.

m.

Funnel segment - 0.25" thick, type 304 S.S.

n.

Coupon plate - 0.35" thick, type:304 S.S.

o.:. Gusset plate - 0.625" thick, type 304 S.S.

.p.

Channel 0.50" thick. type 304 S.S.

Lq., Filler wire'- 0.12"/0.25" dia., Grade 308 or 308L, SFA 5.9, Section'II

-Part'C,.ASME Code.

A sketch of the wrapper plate details Lis included as Attachment 1.

2.

Poison material ~ venting occurs through cutouts at corners of the wrapper

plate. 'The wrapper is spot welded to the cell wall along the vertical

' joint between the wrapper'and' cell.

3.

-There has been no change in the spent fuel pool water boron concentration.

The proposed technical specification changes include a surveillance re-quirement to verify baron concentration once. per 31 days. The boron con-centration in 'the spent fuel pool is to be maintained at greater' than or equal to 2000 ppm..

4. ' Details of the McGuire neutron poison surveillance program are as follows:

Two boraflex coupon stringers will be installed in each McGuire spent fuel pool. In Region 1 a stringer will be ~ attached to rack module 1 (ref.

figures 4.2-9 and 4.2-10) along the non-poison cell wall between modules

-1 and 2.

A Region 2 stringer will be attached to module 3 along the non-poison cell wall between modules 3 and 4.

Each. stringer will contain 24 coupons in 8 packets of 3.

Two coupons will be fabricated from each batch of poison material incorporated in the racks (12Jin Region 1 and 11 in Region'2-for each pool) and mounted on the appro-

~

1 priate stringer.. This will allow 100% representation of all poison batches

L to be maintained throughout the first fsw surveillance periods currently 1 scheduled at five ' year.intervalsa Beyond thia point chemical composition

. and fabrication consistency between batches can safely be assured thus al-lowing continued examinations utilizing the second set of coupons.

. As detailed in the attached sketch, each set of.3 coupons is to be mounted between two : 75 mil stainless steel plates. This arrangement closely re-sembles that of'the boraflex mounted on the rack cells. Wrapper and cell material is also 75 mil stainless.

It.is expected that-Region 1 will be utilized for only periodic short term

' storage of irradiated fuel assemblies.

Specifically, freshly discharged fue1' assemblies will be placed in Region 1 until their transfer to Region

2. following minimum burnup verification.

Plant refueling procedures will ensure that the stringers in each region receive a bounding cumulative gamma and neutron dose through placement of the " hottest" fuel assemblies-in cells adjacent to the stringers.

Calculations ofLnominal radiation exposure of poison material in high den-sity poison racks predict -cumulative gamma dose of % 1x1011R (which corre-sponds to the maximum test exposure of Boraflex) in.approximately 5 years.

. Cumulative exposure to each McGuire region.will be somewhat less than that since storage time.will'be divided between the 2 regions.

Nevertheless, 3 coupons from each stringer will be examined no later than 5 years af ter the s

first discharge of irradiated. fuel into the racks.

Additionally, some actual poison performance data will become available ap-proximately 2-3 years into the program from =the Oconee surveillance program currently-underway. The Oconee program is very similar to the proposed McGuire program in that it utilizes Boraflex as the poison material and re-quires,similar fuel loading procedures that insure maximum exposure to the coupons.

Results of the Oconee program will be used to determine the need for_ examinations sooner than 5 years at McGuire. Beyond the first 5 year surveillance period,'the necessity-for shortening a particular 5 year period will be determined by the results of the preceeding examination.

- Coupon testing with include a visual inspection for evidence of corrosion, cracking, or crumbling. The following physical and mechanical roperties will be measured: width, thickness, weight, specific' gravity, B 0 content, hardness (as an indicator of embrittlement), and tensile strength.

Addi-tionally, a measurement of neutron attenuation will be recorded for each specimen. All tests will be consistent with the original qualifying tests of each batch. A sketch of surveillance specimen details is included as.

ATTACHMENT 1 -

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2. SIDE FLANGES AND TIP OF END TABS TO BE COPLANAR IN.50 ZONE AT EACH END OF WRAPPER. XNIFE EDGE ON END TABS AND AS-SHEAREO INTERN AL EDGE CONDITIONS ACCEPTABLE.

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