ML19095A302
| ML19095A302 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 09/29/1978 |
| From: | Stallings C Virginia Electric & Power Co (VEPCO) |
| To: | Harold Denton, Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| Download: ML19095A302 (6) | |
Text
{{#Wiki_filter:e REGULATORY ooctr FILE COP! VIRGINIA ELECTRIC ~ND POWER COMPANY RJ:CHMOND,VJ:BGJ:N.IA 23261 {=:> C) ~ September 29, 1978 ~-i~ r-:;?~
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--1C Mr. Harold R. Denton; Director Nuclear Reactor Regulation
- u. S. Nuclear Regulatory Commission Wash1:rigton, D. c.*
20555 Attn: Mr. Albert Schwencer, Chief* Operating Reactors Branch 1
Dear Mr. Denton:
.....,) --t Cl a Serial ~o. 296ffv030578= PO&M/RWC: scj *' V Docket.Nos.* 50..;280 50-281 License Nos. DPR-32. DPR-37 LaSalle Hydraulic Laboratory of Montreal, Canada has completed a hydraulic model study of the suction piping and pump-can configuration for the* outside recirculation spray (ORS) pumps and low head safety* injection (LHSI) pumps at Surry Power Station Units Nos. 1 and 2. The observed flow conditions were judged.by the.respective pump manufacturers to be entirely satisfactory with rio reduction in pump performanceor excessive bearing wear anticipated*.
- However~ in acknowledgement of the NRC concern for pump operability, LaSalle was requested to develop a device to improve the suc-tion flow conditions.
As a result of these efforts an. extension to the pump bell is pro-posed* for both pump-can des.igns. This device minimizes head losses and pro-vides stable radial flow into the pump suction. These modifications will be :inade to*Unit No. 1 and 2 ORS and LHSI pumps during the respective outages for steam generator replacement. Unit No. 1 and 2 modifications should be incorporated by June and.December, 1979 respectively. ORS Pump A hydraulic model test of the existing design revealed small ran-dom air-core vortices originating at the can wall and floor. Vortices of this nature were riot observed*during testing of the North Anna ORS pumps. The inlet.piping arrangement is similar for both plants, however the* Surry pump is located*10 inches rather thari 4 inches off the can floor creating a turbulent.region. For ease of installation a modification to the pump rather than to the can was requested. Various designs were tested* and a final modifi-cation was developed which ensured a smooth radial approach to the pump bell for the full range of flow rates. Aoof f s
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L e VIRGINIA ELECTRIC AND PowER CoMPA.'IT To
- Mr. Harold R~ Denton Figure 1 provides a sketch of the modification.
The upper*half of the* cross--vane
- cage is enclosed~.. The lower* eight *apertures*. are open*
to* the flow between the cross--vanes. *. The* flow entering each aperture is confined between* the cross-vanes* and di:i::ed:ed* vertically upward to- . ward the* bellmouth. This region is 4 1/211° high corresponding to 0.25 of the bell diameter. Figure 2 shows a cross section of the hydraulic model* including pressure tappings used* for headless measurements.* Figure 3 shows the relative headlosses~
- The original and modified*.design had the same rela-tive headlosses between* the' suction line (tapping:1) and the bellmouth lip (tapping :2).
However the*.relative headlosses* through the discharge line (tapping :4).were reduced by the* inodification. LHSI Pump* A hydraulic model test of the existing des.ign revealed a gentle counter clockwise swirl in the pump--cail annulus r_egion and numerous small air-cote vortices*o~iginating at the can wall and floor. As expected~ the* annulus swirl was*muchless pronounced than for the North Anna test due to thEf *45° rather than 90° pipe.bend prior to entry into the* can. The proposed* modification is a design similar to*: that developed for the**oRS pumps.* Figure 4 shows* the relative*headlosses~ There was no appreciable change in headless measurement~l_af ter attachment of the modification. A final copy of the.LaSalle Hydraulic Laboratory.report.concern-ing thei.:t moder tests wi.11 be submi.tted* as it becomes available.* You wi.11 be noti.fied*when all the*inodifications*are installed~ .Very truly yours, C. M. Stallings / Vice President-Power Supply and Production Operations cc:
- Mr. James* P ; 0 'Reilly
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