ML20010E303
| ML20010E303 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 08/14/1981 |
| From: | Stolz J Office of Nuclear Reactor Regulation |
| To: | Bauer E PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| References | |
| REF-GTECI-A-10, REF-GTECI-RV, TASK-A-10, TASK-OR NUDOCS 8109030307 | |
| Download: ML20010E303 (2) | |
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DISTRIBUTTON Docket No. 50-277/278 yet F1 e3 NFairtile n w run RIngram L PDR TNovak y
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Mr. Edward G. Bauer, Jr.
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Vice President and General Counsel DEisenhut Philadelphia Electric Company 0 ELD f
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Dear Mr. Bauer:
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SUBJECT:
IMPLEf1ENTATION OF UNRESOLVED SAFETY ISSUE A-10, BWR N0ZZLE CRACKING By letter dated July 10, 1981 you responded to our letter of June 10, 1981 regarding the above subject. The particular concern addressed in our Jun 10 letter was your proposed installation of filters in the control roc drive (CRD) hydraulic system flow stabilizer loop as an alternative to the replacement of carbon steel piping with stainless steel.
The statements in Appendix 0 of NUREG-0619 with regard to filters were based upon a General Electric letter (MFN-269-79) of November 2,1979 i
to the NRC. Attachment No. 3 to that letter provided detailed responses to questions raised by the NRC staff during its review of the proposed CRD hydraulic system modifications.
The applicable question and answer are reproduced here:
"In reference to the May 22, 1979 submittal on CRD Hydraulic Control System Return Line Modifications for Operatina Plants, provide the following:
a.
Should a licensee choose to retain the existing carbon steel piping rather than replacing it with stainless steel, describe and discuss the circumstances under which it would be acceptable to permit power operation without installing the 50 micron particulate filters in the cooling water line, i
Response
i The original GE recommendation for the installation of the subject filters in the cooling water header was primarily based on the expectation that, with the return iine eliminated, there would be flow from the exhaust water header to the cooling water header r
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is typically a 200 foot length of 1" or lh" carbon steel pipe.
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~ (1109030307 810si4" this relatively long length of carbon steel piping, it was PDR ADOCK 05000277 i
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p the judgpent of GE Fagineering that the subjpct filtersAphould be g
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added to filter the flow from the exhaust water header.
Subsequent testing at an operating plant, however, revealed that the flow to the exhaust water header from drive movenents was not discharged into the cooling water header.
Instead, the flow exhausted from the moving drive was observed to discharge directly back up to the reactor pressure vessel (RPV) via a reverse flow path through the insert exhaust directional control valves, (i.e., the HCU-121 valves),
of adjacent Hydraulic Control Units (HCUs). With the recommended installation of the pressure equalizing valves between the cooling water and exhaust water headers, the stabilizer loop flow is consequently the sole source of flow to the cooling water header which goes through carbon steel pipe and is not subsequently filtered.
The potential for carbon steel corrosion particles to be generated in this short run of piping is addressed in detail in the response to question #3. As concluded in that response, the contribution of carbon steel corrosion particles to the cooling water flow from the carbon steel piping of the stabilizer loop is comparatively small in elation to the carbon steel corrosion particles which are already in the flow.
Therefore, although the GE recommendation is still directed toward a more absolute solution through the replacement of the carbon steel piping in the flow stabilizer loop with stainless steel or the installation of the subject 50u filters in the cooling water header, the alternative action of "do nothing" is considered to be acceptable."
You should note that the stabilizer loop does provide flow to the cooling water header and therefore the potential exists for contamination of the header with carbon steel corrosion products and subsequent deleterious ef fects upon CRD operability. This fact plus the staff's basic mistrust of unmonitored filter systems weighed heavily in our initial decision not to accept filter systems in lieu of removal of the carbon steel pipe end its replacement by stainless steel.
However, your proposed system for Peach Botto$ Units 2 and 3 does incorporcte differential pressure alarms for the filters.
Such alarms, in the control room, will aftert the operators to potential contanination of the cooling water header.
Therefore, although the proposed filter installation deviates from the guidance of i;UREG-0619, we find it acceptable based on the protection afforded by the installed alarms.
This completes our review of your proposed implementation plars for the guidance contained in fiUREG-0619.
We anticipate receiving your post-modification reports in accordance with the guidance of i4UREG-0619.
SiG6ffdbiL simE:D BT T J01CiF. STOLT&T John F. Stolz, Chief Operating Reactors Branch #4 Division of Licensi l
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