ML19207B984
| ML19207B984 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 08/30/1979 |
| From: | Parker W DUKE POWER CO. |
| To: | Baer R, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7909060276 | |
| Download: ML19207B984 (7) | |
Text
DUKE POWER COSIPANY Powen Scrx.ntxo 422 SocTu Caracu SrazzT, Crunt.oTTE, N. C. 28242 WI LLI AM O.PARMER,JR.
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c, Mr. Harold R. Denton, Director U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, DC 20555 Attention:
Mr. Robert L. Baer, Chief Light-Water Reactor Project Branch No. 2 Re: McGuire Nuclear Station Units 1 and 2 Docket Nos. 50-369, 50-370
Dear Mr. Denton:
Due to floor elevation changes in the vicinity of the McGuire containment sump, it was necessary to modify the sump screen design presented in Figures 16 and 24 of Alden Research Laboratory Report No. 29-78/M208JF which was transmitted to you on June 30, 1978 as part of Amendment 53 to the McGuire license application. Attachments 1 and 2 are marked up figures from this report showing the changes. We have reviewed these changes and have con-cluded that they would not adversely affect sump performance. Attachment 3 is a letter from Alden Research Laboratory to Duke Power Company which supports this conclusion. is a discussion of the net positive suction head (NPSH) avail-able to the containment spray (CS) and residual heat removal pumps under the most limiting conditions. Attachment 5 is the data obtained from measurements taken during preoperational tests.
This data was the basis for the information supplied in Attachment 4.
If you have any questions regarding any of the attached information, do not hesitate to contact us.
Very truly yours,
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ALDEN RESEARCH LABORATORY 7
WORCESTER POLYTECHNIC INSTITUTE May 3,
- 1979l, Duke Power Company 422 South Church Street Charlotte, MC 28242 Attention:
Mr.
S.K. Blackley, Jr.
Chief Engineer Mechanical and Nuclear Division McGUIRE MUCLEAR PCWER STATICS CC:I~AISME';T SUMP MCCEL TESTS MGLC/BESOS-ARL-238F
Dear Mr. Blackley:
This is in response to your letter dated April 27, 1979 requesting us to review the changes in the screen design of the McGuire Containment Sump.
The reduction of screen area of 164 square feet to 135 scuare feet will in-crease the approach velocities to the screen by about 201, from 0.193 to 0.24 ft/sec. As the submergence of the pipe (pipe centerline still at EL 726) and the overall sump orientation are not changed, no ma:Or changes in the flow pattern to the sump and to the pipe are expected with the new changes in screen ar
. Hence, the position of the vortices would be more or less the same as previously observed in the model tests.
Earlier tests have showed that even with prototype velocities in the model suction pipes, the most severe vortices were of weak dye core type, and these were dis-rupted by the vortex suppressor gratings provided in the reccamended design (F.igures 15, 16, and 24 of ARL Report No. 29-78/M208JF).
Separate studies on vortex suppression gratings conducted for Duke Ecwer at ARL and reported in ARL Report No. 62-78/M2080F (submitted tc Ocke Power) have indicated that the vortex suppressor gratings recommended for the McGuire sump are capable of suppressing air-core vertices (generatcd cy lowering the sub-mergences f ar below design values), under the same discharge conditions.
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even if the proposed change in the scraen design increases the vortex strength, the suppressor would act in climinating the existence of any ccherent core and as such no air-entraining vortices are possible.
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May 3, 1979 As no major changes in the flow pattern in the sump vicinity and at the pipe entrance are likely with the proposed screen area changes, no practical in-creases in the swirl or entrance losses are anticipated. However, due to the increase in approach velocity, the screen losses would be somewhat in-creased. The expected screen losses with the proposed screen area raducrion would be about 0.6 inches of water, which is small compared to the total in-take losses.
Based on the above factors, the proposed changes in the screen area will not contribute to any adverse changes in flow conditions in terms of vortexing, swirl, or inlet losses in the sump behavior relative to those predicted by ARL hydraulic model tests, reported in ARL Report No. 29-73/M208JF.
If you have any questions, please feel free to contact us.
Sincerely, O 's
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ATTACHMENT 4 Net Positive Suction Head (NPSH) Preoperational Verification Test For Containment Spray Pumps To demonstrate that adequate NPSH is provided for the Containment Spray pumps, a preoperational test was performed simulating the injection mode (suction from the Refueling Water Storage Tank) and the test results were extrapolated to the recir-culation mode which is the most limiting alignment for NPSH requirements. Actual NPSH available was determined from the following operation:
(h) RWST
- (h) vapor
+ (h)* suction + (h) pressure + (h) fluid NPSH
=
actual or pressure pressure gauge velocity containment elevation correction pressure correction To extrapolate available NPSH from the containment sump instead of the RNST, several conservatisms were applied:
a.
No increase in RWST (Containment) pressure from that present prior to the test (accident) is assumed.
b.
The RWST (Sump) temperature during the test was approximately 700F, however, 0
a Containment sump fluid temperature of 190 F was assumed.
c.
The suction pressure was extrapolated to the Containment sump floor elevation (elevation 725' + 0") instead of using the actual suction pressure due to RWST water level during the test.
Also, the piping losses from the RWST which are included here are higher since the sump suction alignment utilizes shorter piping lengths. No credit is taken for the decrease in piping losses when aligned to the Containment sumo. Piping losses were extracolated from 3450 gpm (test flow) to 4000 gpm (runout flow).
d.
Corrections were made for pressure gauge elevation and fluid velocity.
Using these conservative assumptions, the actual NPSH available was 32.6 feet.
Since the Residual Heat Removal pumps are identical to the Containment Soray pumps and are located at the same plant elevation, the actual NPSH available from this preoperational test will apply for the RHR and CS pumps.
NOTE: *This infomation was obtained during the test and therefore accounts for both static head and suction piping losses.
31.2iB
ATTACHMENT 5 Preoperational NPSH Verification Test Data, For Containment Spray Pumos Pump flow rate, gpm 3450 Pump suction pressure, psig 34 Pressure gauge wrt pump suction centerline, ft
-0.9 Storage tank level, ft 25 Storage tank bottom elevation, ft 760 Sump bottom elevation, ft 725 Pump suction centerline elevation, ft 701 Storage tank water temperature, OF approx 70
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