ML20197D596

Responds to 860214 Request for Addl Info Re 851216 Application for Amend to License SNM-1067,increasing Slab Thickness for Fuel Rods Stacked in Trays.Requests Approval of Rev to Encl Page I.4-14 of License

ML20197D596
Person / Time
Site:	07001100
Issue date:	03/18/1986
From:	Lichtenberger ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY
To:	Ketzlach N NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
References
26702, NUDOCS 8605140303
Download: ML20197D596 (5)

Text

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RETURN TO 396-SS License SNM-1067 O

Docket 70-1100 f)

.A March 18, 1986 RECBVED

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U. S. Nuclear Regulatory Commission O 31 1986 p U.S NUCLEAR RlGULATCRt (2

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Washington, DC 20555 Attention:

Mr. Norman Ketzlach Ma;Ik$a Uranium Process Licensing Section y

.,\\f Uranium Fuel Licensing Branch

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Division of Fuel Cycle and Material Safety, NMSS

Subject:

SNM-1067

Reference:

1) Memo from H.

V.

Lichtenberger, CE, to Thomas T.

Martin, NRC, Dated December 16, 1985

2) Memo from N.

Ketzlach, NRC, to H.

V.

Lichtenberger, CE, Dated February 14, 1986 Gentlemen:

Reference 1 requested approval to make certain changes to the subject license regarding an increase in slab thickness for fuel rods stacked in trays and stored in the covered storage array or held on pre-stacking carts.

Reference 2 commented on che Reference 1 submittal and requested additional information as noted below 1.

NRC COMMENT Provide justification for the nuclear criticality safety or arrays of 6-inch deep boxes of close-packed fuel rods at a water-to-fuci volume ratio of 0.48 (see Secticn 8.3.3).

An isolated, 6-inch thick water reflected infinite slab of closely packed fuel rods is safe under these conditions.

RESPONSE

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See comment 3 below.

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2.

NRC COMMENT

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Your request for approval of a 5.5-inch thick slab of 1 3 93 rods in storage boxes placed in the Double Shelf Rod S o gqj~' imp 3 l&

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1 v n' Power Systems 1000Prospndil Road (203) 688-1911 Combustion Engineenng. Inc.

Post Office Box 500 Telex: 99297 Windsor, Connecticut 06095-0500 8605140303 AAnm sa PDR ADOCK 6766iiOO C

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To:

U. S. Nucle 2r Regulatory Commission

-2 Lic:nso ^ SNM-1067 Attention Mr. Norman Katzlach

'Dockat 70-1100 Rack and for a 6-inch thick slab of fuel rods in the sama type storage boxes when positioned in the multi-tiered Fuel Rod Storage Rack is a poor practice.

The plant operator may not only be confused by the apparently conflicting criteria but the criteria can be very misleading.

No justification has been provided for the double standard.

RESPONSE

We agree that there may be confusion on the part of the operator.

Accordingly, we are requesting approval of the revision to Page I.4-14 of the license (copy attached).

The proposed revision allows us to post the double shelf rod storage racks with a 6.0" maximum slab height.

3.

NRC COMMENT In addition, Mr. Jerome Roth, Region I Fuel Facility Inspector, has informed me that he noted as many as 20 hollow tubes in a single storage box containing "close packed" rods.

It appears this arrangement not only violates the close packing criteria but also introduces the possibility of water-to-fuel volume ratios 0.48 in the box, under accident conditions.

RESPONSE

i The resulting water-to-fuel ratio with the 20 hollow tubes

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in the storage tray is still less than 0.48.

The original 0.48 water-to-fuel ratio was calculated assuming that the fuel pellet clad gap was full of water.

The resulting water-to-fuel ratio with the 20 fuel positions remcVed and their space occupied by water is 0.37.

This is still less than the 0.48 ratio referred to in your comment.

4.

NRC COMMENT i

The referenced Figure 1.E.16 of the UKAE Handbook, AHSB -1, does not provide the indicated information.

Extrapolation of the data is necessary. Although the staff believes your extrapolation may be non-conservative, a more conservative extrapolation confirms the nuclear criticality safety of a single, isolated slab of close-packed hexagonal 19 spaced fuel i

rods having a maximum water-to-fuel volume ratio of 0.48.

It appears you are misusing the safety factor of 1.2 for in-dividual slabs.

It applies to known critical ~ slab-thicknesses.

RESPONSE

The extrapolation was done in what was considered to be a conservative manner.

It has been shown by analysis that a

To:

U.

S. Nucitar Requistory Commission Licznsa SNM-1067 Attention Mr. Norman Ketzlach Docket 70-1100 the reactivity decreases very rapidly with reduced water-to-fuel ratios.

The noted extrapolation was done using the same curvature above 1.0 on the water-to-fuel volume ratio curve.

Even with this conservatism the 1.2 factor was applied to the 'results giving a safe factor well above the 6-inch slab limit which is being applied to the rod storage tray.

Very truly yours, L

D

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H.. V.

Lichtenberger Vice President, Nuclear Fuel Nuclear Power Systems Division HVL/RES/ sam

Attachment:

Page I.4-14, Rev. 4, Dated 12/16/85

avarago.

Rscordo of thsee inspsction shall be maintainsd.

4.3.7 For enrichments 43.5 wt.% U235, the 11" diameter x 40" long cylindrical press feed hoppers with conical tops shall be used.-

For enrichments between 3.5% and 4.1%, the'10.5" diameter x 17.7" long cylindrical hoppers with flat tops shall be used.

When enrichments 3.5% are being processed, the larger hoppers shall be stored under lock and key.

The key shall be controlled by the pellet shop supervisor.

4.3.8 In the Concrete Block Storage Area, all heterogeneous material shall be con *=inaa_in 3.-1/2_gallonsor smaller containers and all homogeneour mhteri~al shall 'be ' contained in 5-gallon or, smaller containers.

Each, storage position shall be limited to one container. __ m :

4.3.9 UO2 thickness on--each' of'ihe Pellet Storage Shelves shall be I

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less than 4 inches.

The shelve.Y shall be covered from above by a sheet metal top.

4.3.10 Storage of sintered pellets only at W.S.

P-15,P-19,P-21 shall be limited Eo a 5.'5 ilichslib"lliniti.

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4.3.11 Touching clad rods in horizor.tal storage shall be close packed in a hexagonal lattice..and shall be. limited to a 6.0 inch slab.

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cm 4.3.12 A maximum of 32 fuel rods slafl~Ee allowed in each Autoclave (W.S. 116-121).

4.3.13 The boxes on the Double Shelf Rod Storage Racks shall be covered with a tight fitting aluminum cover which overlaps the outside edge of the box by a minimum of one inch.

Fuels rods shall be close packed in a hexagonal lattice and shall be limited to a 6.0 inch slab within the individual rod boxes.

One box may License No. SNM-1067, Docket 70-1100 Rev. 4 Date: 12/16/85 Page:'I.4-14

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