ML20214X223
| ML20214X223 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 06/10/1987 |
| From: | Standerfer F GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML20214X226 | List: |
| References | |
| 0193P, 193P, 4410-87-L-0092, 4410-87-L-92, NUDOCS 8706160385 | |
| Download: ML20214X223 (2) | |
Text
9 GPU Nuclear Corporation Nuclear
- eme:r8o o
s Middletown, Pennsylvania 17057 0191 717 944 7621 TELEX 84-2386 Writer's Direct Dial Nurnber:
(717) 948-8461 4410-87-L-0092 Document ID Ol93P June 10,1987 US Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
Dear Sirs:
Three Mile Island Nuclear Station, Unit 2 (TMI-2)
Operating License No. DPR-73 Docket No. 50-320 Filter Canister Media Modification In an effort to reduce the potential for clogging of the filter canister filter elements, the pore size of the filter bundle in some of the filter canisters has been increased from 0.5 microns nominal (2 microns absolute) to 16 microns nominal (25 microns absolute). The new filter elements will be installed in filter canisters and will be used in a manner identical to the previous design.
Attached for the information of the NRC TMICPD is an evaluation which demonstrates that the safety aspects of the canisters containing the new filter media are bounded by previous structure and criticality safety analyses.
l Sincerely, I706160385 870610 v
PDR ADOCK 05000320
".. Standerf r P
PDR Director, TMI-2 FRS/RDW/eml Attachment cc: Regional Administrator, Region 1 - W. T. Russell Director, TMI-2 Cleanup Project Directorate - Dr. W. D. Travers t
\\
GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation i
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ATTACFNENT 1 4410-87-L-0092 EVALUATION OF THE FILTER CANISTER MEDIA MODIFICATION In an effort to reduce the potential for clogging of the filter canister filter elements, the pore size of the filter bundle in some of the filter canisters has been increased from 0.5 microns nominal (2 microns absolute) to 16 microns nominal (25 microns absolute). The new media is similar to that previously utilized in that it is comprised of sintered stainless steel. The new media also is designed to allow backflushing at higher pressure differentials (a maximum of 25 psid). The new filter elements will be installed in the filter canisters and will be used in a manner identical to those currently in-service. As a result of the change in the design of the filter media, it was found that the overall filter bundle weight increased slightly. The below evaluation demonstrates that the safety aspects of canisters containing the new filter media are bounded by previous structural and criticality safety analyses.
To ensure that the structural analyses performed for the previous filter media are conservative when applied to the new media, a series of bench tests were performed by Babcock and Wilcox (B&W) (Attachment 2) to assess the load carrying capability of the new elements. In these tests, new production filter elements were subjected to a series of axial and lateral forces. The load carrying capability and overall element deflections resulting from these forces were then compared to similar tests performed on the original filter elements. This comparison showed that the axial and lateral load carrying capabilities of the new elements exceeded those of the earlier design. Additionally, the deflections resulting from the applied loads were less than those experienced earlier. Thus, GPU Nuclear concludes that the previous structural analyses are bounding when applied to the new filter elements.
Regarding previously performed criticality analyses, it is noteworthy that the only change to the internals of the filter canister is the change in the filter media design. As previously described, the filter bundle with the new media design is slightly heavier than the previous bundle. This increase, resulting from an increase in the quantity of stainless steel within the canister, should result in a greater neutron poisoning effect. This conclusion is based on previous canister evaluations which have shown that an increase in stainless steel within a canister will result in a lower neutron multiplication (kerr). Therefore, GPU Nuclear concludes that, in the normal configuration, canisters employing the new media will have a kerr less than that calculated for the original media design.
In the design accident configuration, the internals of the filter canister are deflected to one side as a result of the dropping of the canister. The increase in the canister k rr as a result of this deflection has been shown to increase with e
increasing deflection. Attachment 2 indicates that the new elements have greater load carrying capabilities; therefore, less deflection will result. Thus, the potential increase in kerr, resulting from the design accident, will be bounded by that expected for the original filter media design.
Based on the results reported in Attachment 2, GPU Nuclear has determined that the new filter media will have no adverse impact on existing analyses. Therefore, the normal and accident kerr's for the filter canisters as calculated for the original filter design (i.e., 0.839 and 0.892 respectively) are bounding for filter canisters containing the new filter media (i.e., 16 micron nominal). This modification will be addressed in the next annual update to the Defueling Canister Technical Evaluation Report.