ML20215B132

Informs of Mods to Several knock-out Canisters for Use as deep-bed Filters in Defueling Water Cleanup Sys.Use of deep-bed Filters Intended to Improve Clarity of Reactor Vessel Water.Conceptual Drawing of Mod Encl

ML20215B132
Person / Time
Site:	Crane
Issue date:	09/26/1986
From:	Standerfer F GENERAL PUBLIC UTILITIES CORP.
To:	Travers W Office of Nuclear Reactor Regulation
References
0113P, 113P, 4410-86-L-0173, 4410-86-L-173, NUDOCS 8610060376
Download: ML20215B132 (3)

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GPU Nuclear Corporation g

gf Post Office Box 480 Route 441 South Middletown, Pennsylvania 17057-0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:

(717) 948-8461 4410-86-L-0173 Document ID Oll3P September 26, 1986 TMI-2 Cleanup Project Directorate Attn: Dr. W. D. Travers Director US Nuclear Regulatory Commission c/o Three Mile Island Nuclear Station Middletown, PA 17057

Dear Dr. Travers:

Three Mile Island Nuclear Station, Unit 2 (TMI-2)

Operating License No. DPR-73 Docket No. 50-320 Deep-Bed Filters In The DWCS The purpose of this letter is to inform you of modifications being made to several knock-out canisters.

These canisters are being modified for use as

" deep-bed" filters in the Defueling Water Cleanup System (DWCS).

The use of these " deep-bed" filters in the DWCS is intended to improve the clarity of the reactor vessel water.

The modifications being incorporated into the knock-out canisters include:

Cutting the existing inlet tube below the support ring, o

Adding a 2" 0.D. stainless steel pipe as an outlet tube, o

Routing the outlet tube through the gap between two legs of the o

support spiders, Sizing the support ring to accommodate the outlet tube, and o

Extending t.he cutlet tube down to within 1" of the bottom plate.

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1 8610060376 860926 OY j

PDR ADDCK 05000320 13f P

pon GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation

Dr. Travers September 26, 1986 4410-86-L-0173 The bottom 12" of the extended outlet tube will have multiple 1/4" to 3/8" holes and will be covered with a 100 mesh stainless steel screen. The outlet tube will be attached to one (1) or more support spiders to prevent significant motion of the outlet tube during canister handling. These minor modifications are expected to have no adverse impact on the previous structural evaluations performed on the knock-out canisters. The canister designer is currently reviewing these modifications to confirm this.

GPU Nuclear will inform you if any significant deviations to the previous structural evaluations are discovered.

Additionally, the filter media to be used in the modified knock-out canisters is diatomaceous earth (d.e.) and sand. The use of d.e. in the filter and knock-out canisters has been previously addressed in GPU Nuclear letters 4410-86-L-0063 dated April 14,1986 and 4410-86-L-0104 dated June 30, 1986, which have been reviewed and approved by the NRC. The use of sand, which is coarser than d.e. is bounded by the analyses in the referenced documents.

Further, the differential pressure across the modified knock-out canisters will be limited to 100 psi. The DWCS and the defueling canisters are designed for operating pressures of 150 psig.

A conceptual drawing of this modification is attached for your information.

The DWCS TER and the Defueling Canister TER will be updated if the " deep-bed" filters prove to be an effective means of reactor vessel water cleanup.

Sincerely, F. R. Standerfer

[

Vice President / Director, TMI-2 FRS/RDW/eml

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CONCEPTUAL ARRANGEMENT FOR CONVERSION OF " KNOCK-OUT" CANISTER TO A D.E. FILTER WHICH CAN BE USED TO CLEAN UP POOLS & RV taPft aS$0Clait$

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