ML20214U897
| ML20214U897 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 09/19/1986 |
| From: | Allen C COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20214U898 | List: |
| References | |
| 1875K, NUDOCS 8610020009 | |
| Download: ML20214U897 (5) | |
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Commonwealth Edison A: 72 West Adams Street, Chicago, Illinois Address Reply to: Post Office Box 767-Chicago, Illinois 60690 0767 September 19, 1986 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
LaSalle County Station Unit 2 Proposed Amendments to Technical Specification for Facility Operating License NPF-18 High Density Spent Fucl Racks NRC Docket No. 50-374
' References (a): UFSAR Section 9.1, Fuel Storage and Handling.
(b): Federal Register Vol. 51 No. 44 dated Thursday, March 6, 1986.
(c): Commonwealth Edison LaSalle Station Unit 2 Spent Fuel Storage Capacity Modification Safety Analysis Report.
(d): Sargent & Lundy's Specification T-3758.
(e): NRC's Position Paper "OT Position for Review and Acceptance of Spent Fuel Storage and Spent Fuel Storage and Handling Applications."
Dear Mr. Denton:
Pursuant to 10 CFR 50.90, Commonwealth Edison proposes to amend Appendix A, Technical Specification, to Facility Operating License NPF-18.
This amendment change is being submitted for your staff's review and approval and is in accordance with References (a) and (b).
This proposed amendment revises the Unit 2 Technical Specifications
.to allow installation of High Density Spent Fuel Racks. The installation of these racks will extend full core discharge capability beyond the year 1990 time frame. The safety analysis provided in this proposal is similar to that preliminary analysis transmittal May 20, 1986 for your review. This will allow a large savings in radiation exposure, disposal of radioactive material and financial cost.
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Mr. H. R. Denton SIptember 19, 1986 This modification is scheduled to be installed in Unit 2 prior to the outage in January 1987. To accomplish the modification prior to core unloading, we will need to start removal of the old racks in October. This will allow approximately six weeks for removal of the old racks, two weeks for installation of the new racks and 4 weeks for cleaning, filling, and flushing of the spent fuel pool.
Attachment A provides background and discussion. The proposed change is enclosed in Attachment B.
The attached change has received both on-Site and Off-Site review and approval. We have reviewed this amendment request and have included an analysis using the standards in Section 50.92 about the issue of no significant hazards consideration. Our review is documented in Attachment C.
Also included with this letter is a safety Analysis Report in Attachment D.
Commonwealth Edison is notifying the State of Illinois of our request for this amendment by transmitting a copy of this letter and its attachments to the designated State Official.
In accordance with the requirements of 10 CFR 170, a fee remittance in the amount of $150.00 is enclosed.
Please direct any questions you may have concerning this matter to this office.
Three (3) signed originals and thirty-seven (37) copies of this transmittal and its attachments are provided for your use per 10 CFR 30.(c).
Very truly rs, C. M. Allen Nuclear Licensing Administrator im Attachments A: Background and Discussion B: Technical Specification Change to NPF-18 C: Evaluation of Significant Hazards Consideration D: Safety Analysis Report cc: Region III Inspector - LSCS A. Bournia - NRR M. C. Parker - IDNS SUBSCRIBED AND SWOR to before[methis,/'/' day of A [n/inl/th,1986 OlW
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Notary Public j
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ATTACISBNT A BACKGROUND AND DISCUSSION There are two spent fuel storage pools at LaSalle County Station.
The existing racks in each of these pools have 1080 fuel storage cells.
In the 1989 to 1990 time frame the station will no longer have full core discharge reserve. Consequently, Commonwealth Edison proposes to replace the existing spent fuel racks for LaSalle Unit 2 with racks of a high density design. These free standing racks *:111 have capacity for the storage of 4073 fuel assemblies and 43 special storage cells. The special storage racks consist of 35 control rod storage cells, five (5) defective fuel storage cells and three (3) control rod guide tube storage cells. The existing channel storage rack will remain intact.
I DISCUSSION i
These spent fuel storage racks provide smooth full length square storage cells of stainless steel in a welded honeycomb structure.
Each storage cell, except on the perJphery of the complete array, is bordered on all four sides by Boraflex neutron absorbing poison sheets sandwiched between adjacent cell walls.
Each rack is supported on the pool floor by five pedestal structures welded to the bottom of the rack. A screw adjustable pad is provided in this structure to be used for rack leveling.
U.S. Tool and Die provides the appropriate tool to make these adjustments from the surface through the cells over the pedestals. The height of the bottom of the rack above the pool floor, resulting from the necessary vertical dimension of the pedestal structure, provides adequate underneath space for cooling water flow.
U.S. Tool and Die was contracted by Commonwealth Edison to perform the seismic-Mechanical, Thermal-Hydraulic, and Nuclear analyses which were necessary to meet the licensing requirements outlined in References (d) and (e). These analyses are documented in Reference (c) and included as Attachment D.
The contractor addressed normal, abnormal and accident conditions in the analyses and concludes that concerns, intent and design basis of References (d) and (e) have been met.
Attachment C addresses four (4) items which indicate that this reracking modification is not likely to involve a significant hazards consideration as defined in Reference (b).
The same failure mechanisms postulated for the existing racks supplied by the NSSS supplier are appropriate and were addressed for the high density racks. The contractor concluded the design is safe for full pool storage of spent fuel assemblies and will maintain a subcritical array k
. during all credible storage conditions. Administrati'ce Controls will be established as appropriate to ensure that the fuel pool remains within design limits for its design lifetime. The design will also maintain a suberitical array for specified external loading conditions, including a fuel drop array for specified external loading conditions, including a fuel drop accident since deformations resulting from the dropping of heavy objects into the spent fuel pool or from effects of natural disasters will not produce a criticality accident. Thermal-hydraulic calculations for various cases were performed to determine the heat-up rate and time until pool boiling following the loss of all spent fuel pool cooling. The conclusion was that sufficient time exists for an alternate cooling source to become operational following abnormal / accident conditions.
The Station Nuclear Engineering Department (SNED) has reviewed Attachment D and determined that it complies with the Updated FSAR. SNED also concurs with the station that the reracking modification is not likely to involve a significant hazards consideration.
Revisions to the Updated FSAR (Reference (a)) will be controlled as part of the modification process. The revised Technical Specification page
.is provided as Attachment B.
The changes effect the fuel storage capacity and the cell pitch and are for Unit 2 only.
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O ATTACHMENT B TECIINICAL SPECIPICATION CHANGE TO NPP-18 1875K L-____
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