ML19309E940
| ML19309E940 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/21/1980 |
| From: | Hovey G METROPOLITAN EDISON CO. |
| To: | Jay Collins Office of Nuclear Reactor Regulation |
| References | |
| TLL-175, NUDOCS 8004250356 | |
| Download: ML19309E940 (2) | |
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'* iter's Direct :.a8 Leber April 21, 1930 TLL 175 TMI Progran Office ATTN:
J. T. Collins, Deputy Manager U. S. Nuclear Regulatory Commission c/o Three Mile Island Nuclear Station Middle town, Pa.
17037
Dear Sir:
Three Mile Island Nuclear Station, Unit II (NI-2)
Operating License No.~DPR-73 Docket No. 50-320 MDHS Filter The MDHS filter, located upstream of the MDHS pumps and heat exchangers, is a 24 element 30 micron absolute filter having 84 f t2 of surface area.
The housing of the original filter procured for MDHS service was cade of carbon steel.
This filter housing is currently being changed to stainless steel. The stainless filter vill.be located in a shielded cask on the east side of the MDHS pump cubicle (in its current location).
The cask is shielded with 3\\" (minimum) lead shielding.
Space exists for additional shielding should it be necessarr. Assuming 80% of the filter housing volume contains Reactor Coolant (at current RCS activity level) and that all radioactive species in the entire RCS envelope light enough to be entrained yet not plated out, decayed to April S0, are loaded as the filter media (i.e. Zr95, Nb95m, Xb95) the radiati:n level above background at the surface of the lead brick cask will not, be greatei than 100 mr/hr.
We conclude, as a result of our fur der study of the " shielded cask filter", that the design is satisfacto y.
This assucption is considered to be conservative on the basis that RCS samples over the past months have contained no visible solids, and on the basis that the fluid must flow through several partitianing paths which will reduce, if not eliminate, the presence of solids in the flow stream. Should solids not be blocked by the partitionia; paths or by the filter a cyclone separator is installed to preven.t hizh densi:y particulate from reaching the pump seal annulus.
The filter is " flanged into 2" stainless schedule 40 piping hence f acilitating its removal. The filter is able to be re otely by-passed using remotely operated valves.
The filter is being ' instrumented with Ap instru=entation to indicate the filters' loading status.
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.j-J. T. Collins TLL 175 To' f acilitate recoval of the cask should. filter removal become absolutely necessary to-perait systen operation, the handuheel (currently bolted to the floor blocking free access to the filter location) is being moved.
A second' cask with a second filter is bei.ng fabricated to ensure that a replacement filter cask is available.
We believe that these changes fulfill the requirement to protect the MDHS in a reasonable, realistic nanner. These changes are our response to the nectings held on March 21, 1980 at the NRC trailer, and the. March 28, -
1980 ceeting in trailer 110.
Sincerely,
/s/ G. K. Hovey G. K.'Hovey Director, TMI-II GKH:GRS: hah cc:
B. Snyder b'
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