ML20198D615
| ML20198D615 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 01/05/1998 |
| From: | Ewing E ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-97-04, GL-97-4, W3F1-97-0287, W3F1-97-287, NUDOCS 9801080236 | |
| Download: ML20198D615 (7) | |
Text
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Ente gy perations, Inc.
Killona, LA 70006 Tel 504 739 0242 C. Ewing. hl go a newam em W3F1-97-0287 A4.05 PR January 5,1998 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555
Subject:
Waterford 3 SES Docket No. 50-382 License No. NPF-38 90-Day Response to NRC Generic Letter 97-04," Assurance of Sufficient Net Posit:ve Suction Head For Emergency Core Cooling and Containment Heat Removal Pumps" Gentlemen:
On October 7,1997, the NRC issued Generic Letter (GL) 97-04. The generic letter requested licensees to provide information to confirm the adequacy of the net positive suction head (NPSH) available for the identified systems within 90 days. By this letter, EOl is providinr the requested 90-day response for the Waterford-3 Steam Electric Facility.
As prescribed in the GL, the request applies to ECCS and containment heat removal pumps that meet the following criteria:
(1) pumps that take suction from the com.nment sump or suppression pool following a design-basis loss-of-coolant accident (LOCA) or secondary line break, or (2) pumps used in " piggyback" operation that are necessary for recirculation cooling
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of the reactor core and containment (that is, pumps that are supplied by pumps
. which take suction directly from the sump or suppression pool).
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9001080236 990105 P i
PDR ADOCK 05000382
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90-Day Response to NRC Generic Letter 97-04, " Assurance of Sufficient Net Positive Suction Head For Emergency Core Cooling and Containment Heat Removal Pumps"
- W3F1-97-0287 Page 2 January 5,1998 I
At Waterford-3, the High Pressure Safety lajection (HPSI) and Containment Spray
'(CS) pumps meet this criteria. These are the only two systems that are required for the mitigation of design basis events which take suction from the Safety injection
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System Sump. The Waterford-3 design does not include the use of piggyback type configurations.
This information is being submitted under oath and affirmation ta accordance with 10CFR50.54(f). Should you have any questions regarding this matter, please contact Mr. T.J. Gaudet at (504) 739-6666 or me at (504) 739-6242.
Very truly yours, 0
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_/' E.C. Lwing Director Nuclca Safety & Regulatory Affairs l
ECE/MKB/jmm Euclosurea:
Affidavit Response to Generic Letter 97-04 cc:
E.W. Merschoff, NRC Regior C.P Patel, NRC-NRR J. Smith N.S. Reynolds NRC Resident Inspectors Office l
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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION in the matter of
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Entergy Operations, Incorporated
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Docket No. 50-382 Waterford 3 Steam Electric Station
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AFFIDAVIT Early Cunningham Ewing, being duly sworn, hereby deposes and says that he is Director, Nuclear Safety and Regulator) Affairs-Waterford 3 of Entergy Operations, incorporated; that he is duly authorized to sign and file with the Nuciear Regulatory Commission the attached 90 Day Response to NRC Generic Letter 97-04; that he is familiar with the content thereof; and thnt the matters set forth therein are true and correct to the best of his knowledge, information and belief.
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'Earif CunninghMn EwinN h
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Director, Nuck.ar Safety & Regulatory Anairs -
Waterford 3 STATE OF LOUISIANA
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) ss PARISH OF ST. CHARLES
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Subscribed and sworn to before me, a}m _ary Public in and for the Parish and State ot above named this s% day of _
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,1998.
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e c Notary Public My Commission expires DAM.
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ATTACHMENT 1 to W3F1-97-0287 Page 1 of 4 RESPONSE TO GENERIC LETTER 97-04 i TEM 1 Specify the general methodology used to calculate the head loss associated with the ECCS suction strainers.
RESPONSE
NPSH Methodology The general methodology used for the Licensing of Waterford-3 to calculate available NPSH to the HPSI and CS pumps is as follows:
NPSHA = h, + h, - h, - hy, where; h, = atmospheric head (ft) h, = suction piping static head (ft) h, = friction head between the fluid source and the pump suction (ft) h, = vapor pressure head (ft) y The application of this methodology for the ca'culation of the available NPSH is provided in the Waterford-3 UFSAR sections 6.2.2.3.2.1 and 6.3.2.2.2.3 for the CS and HPSI pumps, respectively. The methodology utilized at Waterford-3 complies with NRC Regulatory Guide 1.1, " Net Positive Suction Head for Emergency Core Cooling and Containment Heat Removal Systems," with one exception. Regulatory Guide 1.1 states that containment heat removal systems should be designed so that adequate NPSH is provided to system pumps assuming maximum expected temperatures of pumped fluids and no increase in containment pressure from that present before postulated LOCAs. Instead, Waterford-3 has calculated NPSH available using a saturated sump model(that is, the containment atmosphere is conservatively assumed to be at the saturation pressure corresponding to the containment sump temperature). This methodology was found to be conservative (SRP 6.2.2.11.2) as documented in the Waterford-3 Safety Evaluation Report (NUREG 0787).
Since no credit is taken for elevated containment pressure in this saturated sump model, the NPSH calculation can be s!mplified to NPSHA = h,- hr.
Calculational Parameters Sump water levelis based on injection of approximately 64% (383,000 gal.)
of the Refueling Water Storage Pool (RWSP). Injection of tnis water volume
ATTACHMENT 1 3
to W3F1-97-0287 Page 2 of 4 RESPONSE TO GENERIC LETTER 97-04 is ensured by the Technical Specification RWSP volume requirements and the Recirculation Actuation Signal (RAS) setpoint.
Pump elevation is measured from the center of the pump volute.
Friction losses are calculated using the Hydraulic Institute Staridard and maximum pump operating flows.
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Actual piping layouts are used to determine pipe lengths and sizes.
Suction Strainers During the initial licensing of Waterford-3, LP&L performed extensive confirmatory evaluations to address the performance of the SIS sump under
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accident conditions. At that time, the head loss associated with the ECCS suction strainers was determined empirically utilizing a 1:1 scale model of the Safety injection Sump (SIS). The modelincluded the sump, intakes, screen cage, and the containment geometry significantly affecting the approach flow conditions. Screen losses were directly measured under various conditions (i.e.
1 flow, water level, blockage). Waterford-3 submitted a detailed report of the
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model testing by a letter dated June 28,1982. These tests of containment emergency sump hydraulic behavior were performed to study intake head losses and vortex control using a full scale simulation. Supplement 4 to the Waterford-3 SER concluded that the Waterford 3 emergency containment sump design was acceptable, f
Additionally, Waterford-3 performed in-depth evaluations to address the potential for debris plugging of the SIS sump in response to a License Condition included in the Waterford-3 Low Power Operating License (NPF-26, dated December 18, 1984). The fina! results of these evaluations were submitted to the NRC on April 25,1985 and mainly addressed the potential for SIS plugging from insulation and coating debris. The results indicated that there is no potential for SIS sump blockage from these sources. In supplement 10 to the Waterford-3 SER, the NRC provided concurrence with this conclusion.
ITEM 2 Identify the required NPSH and the available NPSH.
RESPONSE
A comparison of the limiting NPSH available and NPSH required is shown below.
These values were calculated using the methodology described above.
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ATTACHMENT 1 to W3F1-97-0287 Page 3 of 4 RESPONSE TO GENERIC LETTER 97-04
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I Flow NPSM NPSH Margin Elevation Friction Pump (gpm)
Available Required
(%)
Head Head (ft.)
(ft.)
(ft.)
(ft.)
HP51 890 25.35 18 40.8 26.95 1.60 CS 2250 27.27
_ 14 94.8 28.83 1.5C These values are the same values used during the Licensing of Waterford-3.
Some inconsistencies between the design basis calculations and other plant documents involving some of the parameters used in the NPSH calculations were documented in April 1997. These inconsistencies were identified as part of Waterford-3's ongoing design basis verification program and have been determined to not affect the operability of any plant equipment. Waterford-3 will revise the affected calculations and the FSAR, as appropriate, in accordance with the corrective action plan developed 'or this condition.
ITEM 3 Specify whether the current design-basis NPSH analysis differs from the most recent analysis reviewed and approved by the NRC for which a safety evaluation was issued.
RESPONSE
As discussed in item 2 above, the current design basis has not changed from that reviewed and approved by the NRC during the initial licensing of Waterford-
- 3. The recently identified inconsistencies will affect certain aspects of the design basis calculations. At this time, it is believed that any resulting changes can be satisfactorily evaluated under 10CFR50.59 with no unreviewed safety questions being identified.
ITEM 4 Specify whether containment overpressure (i.e., containment pressure above the vapor pressure of the sump or suppression pool fluiu) was credited in the calculation of available NPSH. Specify the amount of overpressure needed and the minimum overpressure available.
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ATTACHMENT 11 to W3F1-97-028/
Page 4 of 4 RESPONSE TO GENERIC LETTER 97-04
RESPONSE
The methodology described above assumes vapor pressure is equal to containment pressure (saturated sump). Therefore, the methodology does not rely on increased containment pressure.
ITEM 5 When containment overpressure is credited in the calculation of available NPSH, confirm that an appropriate containment pressure analysis was done to establish the minimum containment pressure.
RESPONSE
Containment overpressure is not credited in ti,e calculation of available NPSH at Waterford-3; therefore, this question is not applicable.
REFERENCES l
- 1. Waterford-3 Updated Final Safety Analysis Report, Sections 6.2 and 6.3
- 2. NUREG-0787, " Safety Evaluation Report related to the operation of Waterford Steam Electric Station Unit. No. 3," dated July 1931.
- 3. Calculation MN(Q)-6-4, " Water Level Inside Containment," Revision 0, dated 11/2/78.
Revision 2, dated 11/4/83.
' 5. LP&L letter W3P85-1149, " Confirmatory Evaluations of the Postulated Failure of Containment Coatings," dated April 25,1985.
- 6. - NUREG-0787, Suppiament 4, dated October 1982.
' 7. LP&L letter W3P82-1755, " Transmit'#.1 of Model Testing of the Safety _
. Injection System Sump Report," dated June 28,1982.
- 8. NUREG-0787, Supplemod 10, dated March 1985.
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