ML19345B105

Forwards Addl Info Re Operability of 18-inch Containment mini-purge Valves,In Response to NRC 801107 Request.No Installations Are 90 Degrees Out of Plane of Piping.Duct Work Damage Is Unlikely Due to Elimination of Debris

ML19345B105
Person / Time
Site:	Farley
Issue date:	11/21/1980
From:	Clayton F ALABAMA POWER CO.
To:	Schwencer A Office of Nuclear Reactor Regulation
References
NUDOCS 8011260159
Download: ML19345B105 (3)

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d' Atb:ma Power Company 600 N;rth 18th street Post office Sox 2641 Birmingnam. Alabama 35291 Teleonone 205 250-1000 M 'il F. L CLAYTON, JR.

~I.%. h senior Vice President Alabama Power y *;.*"

,j, ' :s , .i '1 b i the southem electrc system November 21, 1980

. i.'.'.' ICES Docket No. 50-364 '

.. I Director, Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Phillips Building, Room 116 7920 Norfolk Avenue Bethesda, Maryland 20014 Attention: Mr. A. Schwencer JOSEPH M. FARLEY NUCLEAR PLANT - UNIT 2 CONTAINMENT PURGE VALVE OPE _RABILITY

- Gentlemen: - - - - - - - - - --

During a November 7, 1980, telephone conversation, the NRC Staff requested additional information concerning the operability of the Farley Nuclear Plant - Unit 218-inch containment mini-purge valves.

Alabama Power Company hereby submits the enclosed information in response to the Staff's request.

If you have any further questions, please advise.

Yours very truly,

. L RWS:rt Enclosure cc: Mr. R. A. Thomas Mr. G. F. Trowbridge Mr. L. L. Kintner Mr. W. H. Bradford Boo /

.s I) 8011200/59 . / . .- -. . - _ -

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"RC QUESTICil5 ON COMTAIMMEtlT PURGE VALVE OPERASILITY ,

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l Juring the ::cvember 7,1980, conference call the NRC requested confirmation l that none of :he 18-inch containment mini-purga valves were installed in the worst case configuration reported in the Als-Chalmers Report

'iER-0209 dated December 17, 1979. (flote that :1e specific concern is for an installation with an elbow immediately u , stream of the valve and the valve shaft 900 out of the plane of t're iping).

RESPONSE

l The installation of each mini-purge isolation valve has been reviewed with

respect to the worst case installation outlined in the Allis-Chalmers l Report, i.e. , elbow inmediately upstream of the valve and the valve shaft

! 900 out of the plane of the piping. It has been determined that none of the Unit 2 instLilations are 900 out of the plane of the piping and l that all the installed configurations on Unit 2 are less severe than j the Allis-Chalmers worst case configuration.

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2. QUESTICN:

l Provide an assessment of the structural capability of any ducting or piping of the purge system which is upstream or downstream of the valves and is exposed to the flow conditions associated with the LOCA and the seismic event. The Staff is particularly interested in the effects that loose debris from the pipe or duct system may have on the closure capability of these valves.

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RESPONSE

l l The mini-purge supply and exhaust system inlets inside the containment building are fabricated of ductwork. The duct caenings are located outside the primary shield wall and away fr:r rj lines whose rupture would initiate a LOCA. The duct openings are screened to prevent debris from entering or blocking the ducts. Since the duct openings

! are by design located away from potential debris sources, no significant debris would be expected in the vicinity of the duct openings during an i accident. A transport mechanism that would move debris to the inlet screen, even if debris were in the vicinity, would not exist due to rapid valve c?osure along with the relatively low velocities of approach that would exist several diameters away from the purge system

! inlet. The length of ductwork located inside containment was minimized so that flow developed pressure drop through the ductwork remains negligible. Due to the minimization of ducting, the elimination of potential debris, and the low appro- velocities, ductvtork damage is highly unlikely.  !

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2. REE?C1SE fCO.1TI UEDI Tne piping be: ween the inside and outside mini-purge containment isolation valves was fabricated wi.th a design pressure rating in excess of the peak LOCA pressure. This portion of the systen will, tnerefore, not be damaged by any postulated at ident peak pressure transients.

The portion of the mini-purge system located ou: side of containment, downstream of the containment isolation valves is fabricated of ductwork. In this region, the postulated flow and pressure conditions would tend to cause overpressurization failures c the ductwork, rather than ductuork collapse. These failures would be highly unlikely to interfere with valve operability.

The purge supply and exhaust mini-purge isolation valves, and the ductwork outside containment up to the purge systea filtration unit, have been designed to maintain their structural integrit/ under seismic conditions.

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