ML20198D992
| ML20198D992 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 01/06/1998 |
| From: | Cross J DUQUESNE LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-97-04, GL-97-4, L-98-001, L-98-1, NUDOCS 9801080356 | |
| Download: ML20198D992 (16) | |
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January 6,1998 L 98-001 U. S. Nuclear Regulatory Commiesion Attention: Document Control Desk Washington, DC 20555-0001 Subjectt Heaver Valley Power Station, Unit No I and No. 2 HV 1 Docket No. 50-334, Lleense No. DPR 66 HV 2 Docket No. 50-412, License No. NPF-73 NRC Generic Letter No. 97-04 This letter forwards a response to Generic Letter No. 97-04, Assurance of' Sufficient Net Positive Suction Headfor Ernergency Core Cooling and Containment Heat Removal Pumps.
The infonnation requested in the generic letter is provided in the attachments to this letter. Attachment 1 provides the Unit 1 infonnation and Attachment 2 provides the Unit 2 infonnation.
If you have any questions concerning this response, please contact Mr. J. Arias, Director, Safety & Licensing Department at (412) 393 5203.
Sincerely,
[
J. E. Cross c:
Mr. D. S. Brinkman, Sr. Project Manager Mr. D. M. Kern, Sr. Resident inspector Mr.11. J, Miller, NRC Region 1 Administrator
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AFFIDAVIT COMMONWEALTil OF PENNSYLVANIA)
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COUNTY OF BEAVER
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Subject:
Beaver Valley Power Station, Unit No.1 and No. 2 BV-1 Docket No.59-334, License No. DPR-66 HV-2 Docket No. 50-412, License No. NPF-73
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NRC Generic Letter No. 97-04 Before me, the undersigned notary public, in and for the County and Commonwealth aforesaid, this day personally appeared James E. Cross, to me known, who being duly swom according to law, deposes and says that he is Senior Vice President and Chief Nuclear Officer, Nuclear Power Division, Duquesne Light Company, he is duly authorized to execute and file the foregoing submittal on behalf of said Company, and the statements set forth in the submittal are true and correct to the best of his knowledge, infonnation and belief.
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i ATTACllMENT 1 ileaver Valley linit i 1.
Specify the general methodology used to calculate the head loss associated with the ECCS suction strainers.
, uction Strainer.llcad Loss Methodology:
S The head loss associated with the suction strainers was calculated in the following manner:
The now resistance was calculated by using the pump maximum Cow (3,400 gpm for recirculation spray and 4,500 gpm for low head safety injection), a water depth of 1.75 feet for the recirculation spray pumps and of 2.79 feet for the low head safety injection pumps, and an effective screen width of three feet. (Each half of the sump has a total entrance screen width of approximately 18 feet or more. Since as many as three pumps could be drawing from each half of the smnp, half of the total length of entrance screen (9 feet) has been treated as blocked. This follows the guidance of Regulatory Guide 1.82, which directs that the Dow resistance be based on half of the surface area of the inner screen.)
The Dow resistance of the trash rack prior to the screen was calculated using a standard fonnula for bar reck resistance, using shape factors and velocity head (from Wastewagr Engineerinn by Metcalf & Eddy, Inc.,1972).
The Dow resistance of the large and small mesh screens were calculated using a standard method of calculating screen resistance based upon Dow area, velocity head, and Reynolds number (from 11andbook ofIlvdraulic Resistance, by
- 1. E. Idel'Chik,1960).
This woik is documented in calculation 11387.44 N-42-1.
Net Positivq1prdon llead (NPSii) Mell odolouv:
t Recireylation Spray and I.ow Ilead Safety inie tion Pumps:
s Pump suction pressure, Guid vapor pressure, and sump level were calculated in the containment analysis code (LOCTIC) based upon conditions selected to minimize NPSil for the respective pump. Inlet pumping head loss and sump screen head loss were calculsed based upon a high pump Dow.
liigh llead Safety injection Pumps:
The NPSil was calculated with a FLOMAP model of the safety injection system set up with one Low Ilead Pump feeding two running liigh llead Pumps. The
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, Attaclunent I, Unit I NRC Generic Letter No. 97-04 Page 2 containment pressure and sump temperature were set at representative values (11 psia and 180*F) Cases were analyzed at two Reactor Coolant System pressures. When appropriate, How was limited based upon the pressure conditions through the cavitating venturi on the Low Head Pump discharge, in the
" piggyback" mode, the low head pump output pressure is much more significant than the containment pressure.
Recirculation Sorav Pumns fRS P-1 A&H and RS-P 2A&BH 2.
Identify the required NPSil and the available NPSil.
Required NPSII: approximately 9.8 feet (see UFSAR Page 6.4 13)
Available NPSil: Inside Pumps (RS P lA&B):
12.8 feet Outside Pumps (RS P-2A&B):
12.I feet See UFSAR Figure 6.4-10 (attached) this figure was based on calculation 17781.10 US(B) 256 0 3.
Speelfy whether the current design basis NPSil analysis differs from the most recent analysis reviewed and approved by the NRC for whleh a safety evaluation was issued.
The current design basis analysis has been accepted by an NRC safety evaluation.
In August of 1980, for License Amendment 28, the NRC issued a safety evaluation on the " Proposed Pennanent Modifications to Correct LliS1 and Recirculation Spray Pump NPSil Inadequacies" submitted by Duquesne Light on November 17, 1977 (This data was slightly modified in the Duquesne Light letter of September j
l1,1978, " Corrections to Analysis Relating to Proposed Modifications for NPSil Adequacy".) The available NPSil indicated in the safety evaluation was as follows:
i loside Pumps (RS P 1 A&B):
12.7 feet Outside Pumps (RS-P-2A&B):
12.0 feet in April of 1989, the containment analysis was recalculated, including the NPSli information (calculation 1778110 US(B)-256 0). This resulted in some minor changes to the NPSil curve and the resulting limiting NPSH values:
Inside Pumps (RS-P-1A&B):
12.8 feet Outside Pumps (RS P 2A&B):
12.I feet
. Unit 1 NRC Generic Letter No. 97 04 Page 3 l
Recirculation Snray Pumps (RS P-1 A&H and RS-P-2A&H)(Continued)t These new curves were incorporated into UFSAR Revision 8 (1/90) and are attached (UFSAR Figure 6.410). They were past of the analyses changes done to raise the limiting river water temperatur: to 90'F, a change approved in the safety evaluation prepared for Operating License Amendment 143, transmitted in the 1
NRC (Peter S. Tam) letter of July 27,1989.
4.
Speelfy whether containment overpressure was credited in the calculation of available NPSil. Speelfy the amount of overpressure needed and the minimum overpressure available.
Containment overpressure was credited in the calculation of available NPSil. The contribution of containment pressure is included in the attached NPSil curves.
This calculation was done as part of the containment analysis perfonned with the
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LOCTIC code. The amount of overpressute needed and minimum overpressure available were back-calculated from the LOCTIC calculation as described below.
Values for NPSil, Guid vapor pressure, and containment pressure were extracted from the LOCTIC run supporting the calculttion of NPSil. Using these and the steam tables, containment overpressure (pressure in excess of saturation pressure) required to meet the pump NPSil requirement was calculated for several points.
The results of this work are shown on the attached graph titled "BVPS 1 Containment Overpressure Required."
5.
When containment overpressure is credited in the calculation of available NPSil, connrm that an appropriate containment pressure analysis was done to
- establish the minimum containment pressure.
The parameters used in the containment analysis used for the NPSil calculation weic carefully selected in detennining the minimum NPSil value. The Duquesne Light submittal dated November 17,1977 describes, in detail, the sensitivity studies done to choose the most limiting case for NPSil. These criteria are summarized on page 6.413 of the UFSAR as follows:
- 1. Break Duid Dashing modeled by pressure Dash (results in less sump water)
- 2. One hundred percent spray thennal efficiency (causes faster containment depressurization)
- 3. Maximum engineered safety features operable (faster depressurization)
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a Attachment I, Unit 1 NRC Generic Letter No. 97 04 Page 4 Recirculation Sprav Pumps (RS P l A&B and MS P-2 A&B)(Continued):
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l As is shown in Table 2.3 3 of the November 1977 submittal, the limiting single failure is the hot leg double ended rupture.
The methodology used to calculate the NPSif, including issues related to containment pressure, was submitted to the NRC on November 17,1977 and approved in the NRC safety evaluation for License Amendment 28, dated l
August 27,1980.
I,0w liced Safety inlection (SI P 1 A&H):
2.
Identify the required NPSil and the available NPSII, Required NPSil:
10.6 feet (see UFSAR page 6.3 30)
Available NPSil 11.1 feet See UFSAR Figure 6.310 (attached)
- this figure was based on ca'culation 8700 DMC 2339 2 3.
Speelfy whether the current design basis NPSil analysis differs from the most recent analysis reviewed and approved by the NRC for whleh a safety evaluation was issued, in August of 1980, for License Amendment 28, the NRC issued a safety evaluation on the " Proposed Pennanent Modifications to Correct LilSI and Recirculation Spray Pump NPSil Inadequacies" submitted by Duquesne Light on November 17, 1977. (This data was slightly modified in the Duquesne Light letter of September 11,1978, " Corrections to Analysis Relating to Proposed Modifications for NPSil Adequacy".) The available NPSilindicated in the safety evaluation was 12.1 feet.
In April of 1989, the containment analysis was recalculated, including the NPSil infonnation (calculation 1778110 US(B) 256-0). This resulted in some minoi changes to the NPSil curve and the resulting limiting NPSil value to 12.4 feet.
This new emTe was incorporated into UFSAR Revision 8 (1/90) and was part of the analyses changes done to raise the limiting river water temperature to 90'F.
This change was approved in the safety evaluation prepared for Operating License Amendment 143, transmitted in the NRC (Peter S. Tam) letter of July 27,1989.
a
' Unit 1 NRC Generic Letter No. 97 04 Page 5 Low ilead Safety inlection (SI.P-1 A&ll)(Continuedh In November of 1995, the Duquesne Light Safety System Functional Inspection of the safety injection system questioned some inconsistencies in the calculatans supporting the Low licad Safety injection NPSil calculation. This issue was resolved by recalculating the Low flead pump NPSli curve (in Revision 2 to j
calculation 8700 DMC4339). The new minim'ai NPSl! value (11.1 feet) and the new curve were evaluated in accordance with the guidance of 10 CFR 50.59 and included in UFSAR Revision 15 (1/97). This change has not yet been considered in an NRC SER, but it does not represent a change in methodology or approach, only a refinement for ar.alytical consistency. The new curve is attached (see UFSAR Figure 6.3 10).
4.
Specify whether containment overpressure was credited in the cultmlation of available NPSil. Specify the amount of overpressure needed and the minimum overpressure available.
As was the case for the recirculation spray pumps, containment overpressure was credited in the calculation of available NPSil. The contribution of containment pressure is included in the attached NPSil curve. As was done for the recirculation spray pumps, values for NPSil, fluid vapor pressure, and containment pressure were extracted from the LOCTIC run supporting the calculation of NPSil and from a nm using similar parameters. The containment overpressure required to meet the pump NPSil w.a.s calculated for several points and the results are shown on the attached graph titled "BVPS-1 Containment Overpressure Required."
5.
When containment overpressure is credited in the calculation of available NPSil, confirm that an appropriate containment pressure analysis was done to establish the minimum containment pressure, The parameters used in the containment analysis used for the NPSil calculation were carefully selected in detennining the minimum NPSil value. The Duquesne Light submittal of November 17,1977 describes, in detail, the parameter selection and the sensitivity studies done to choose the limiting NPSH case. The criteria are summarized on page 6.3 30 of the UFSAR, as follows:
- 1. Break fluid flashing modeled by pressure flash.
- 2. One hundred percent spray thennal efficiency.
.. Unit !
NRC Generic Letter No. 97 04 Page 6 1,0w Ilead Safety Inlection (Sl P-1 A&H)(Continued):
As is shown in Tables 2.3-3 and 2.3-4 of the November 1977 submittal, the limiting single failure differs from that of the recirculation spray systems and is the pump suction double-ended mpture. Also, the limiting case is minimum engineered safety features, where the recirculation spray case was maximum engineered safety features. This approach was accepted in the NRC safety evaluation for License Amendment 28, dated August 27,1980.
lilith llend Safety Inicellon (Cil P-1 A.H&C):
These pumps operate in a " piggyback" mode after the system transfers from injection ta recirculation.
2.
Identify the required NPSil and the available NPSil.
Required NPSil: approximately 22 feet (see UFSAR page 6.3 31)
Available NPSil: 58 feet (based on calculation 8700 DMC-2282 0, Add.1) 3.
Speelfy whether the current design-basis NPSil analysis differs from the most recent analysis reviewed and approved by the NRC for which a safety evaluation was issued.
The UFSAR, on page 6 3-31, states that the end of the injection phase operation gives the limiting NPSil requirement. Thus, the " piggyback" mode of operation is not limiting for NPSil. The above-listed calculation confinns this. The calculation was prepared to address concerns raised by NRC Infonnation Notice 88-74 and the addendum written to evaluate a valve change-out.
' Unit 1 NRC Generic Letter No. 97-04 Page 7 Illah llend Safety inlection (Cil P-1 A.B&C)(Continued):
4.
Specify whether containment overpressure was credited in the calculation of available NPSil. Specify the amount of overpressure needed and the minimum overpressure available.
While the above listed NPSU value (58 feet) includes a contribution from an assumed containment pressure of 11 psia and the effect of vapor pressure from 180 F water, the containment pressme is not needed to assure NPS11. Removing the containment pressure contribution (assuming saturated water) results in an NpSil of about 50 feet, still well above the limiting value.
5.
When containment overpressure is credited in the calculation of artilable NPSif, confirm that an appropriate containment pressure analysis was done to estahllah the minimum containment pressure.
No contaimnent overpressiire is required.
A'ITACllMENT 2 llenver Valley Unit 2 1.
Specify the general methodology used to calculate the head loss associated with the ECCS suction stralners.
Suction Strainer llend I oss Methodology:
The suction strainer head loss (trash rack & screens) used in the Net Positive Suction llead (NPSil) calculation is based on test data from a model of the containment sump. This data was presented as a graph of heid loss vs.
containment water level in the report of the containment sump model studies conducted by the Alden Research Laboratory, dated August 1983.
NPSil Methodology:
}<ecircultition Spray Pumps:
As presented in UFSAR Section 6.2.2.3.2, the Recalculation Spray Pump NPSil was calculated using the salmated sump assumption (no credit was taken for containment pressure). The containment sump level was calculated by LOCTIC for the Pump Suction Double Ended Rupture 1.OCA, with minimum engineered safety featmes (ESP)(only one quench spray pump running)in order to Gnd an appropriately conservative sump level. Inlet piping head losses were calculated for high pump Gow and the screen head loss was based upon containment water level as described above.
Low Ilead Safety iniection Pumps These pumps do not draw from the containment sump at Beaver Valley Unit 2.
[lighlica i Safety Iniection Pomm:
The NPSil was calculated v ith a Fl.OM AP model of the safety injection system set up with one Recirculation Spray Pump feeding two running High llead Pumps.
The containment pressure, water level, and Guid temperature were assumed based upon the minimum ESF containment analysis. Cases were analyzed for all of the possible pump combinations to Gnd the limiting NPSil line-up, in the " piggyback" mode, the low head pump output pressure is much more signi6 cant than the containment pressure.
d. Unit 2 NRC Generic Letter No. 97 04 i
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Page 2 F
B.tfir.gution Sorav (2RSS*P21 A.B.C&Mr 2.
Identify the required NPSil and the available NPSil.
Required NPSil: 15 feet (at 3,480 gpm).
Available NPSil: 15.9 feet (see UFSAR page 6.2 53 and Table 6.2-59)
This was based on calculation 12241.00 US(B) 1591. This calculation neglected any contribution from containment pressure (used the saturated sump model). The calculation addressed four conditions, pump start (before flow is fully develop:d),
spray start (the first steady state flow condition), beginning of the return of reeirculation spray to the containment floor, and switch over. At the beginning of spray, there is 0.9 feet of NPSil margin. (The margin continued to rise to the switch over case, where it was more than 5 feet, due to increasing water level.)
3.
Specify whether the current design basis NPSil analysis differs from the most recent analysis reviewed and approved by the NRC for which a safety evaluation was issued.
This data was presented in the FSAR at.d has not changed since the calculation was developed in 1983. The NRC safety evaluation is presented in Section 6.2.2 of NUREG-1057, dated October 1985, and NUREO 1057, Supplement 5, dated May 1987.
4.
Specify whethar containment overpressure was credited in the calculation of available NPSli. Specify the amount of overpressure needed and the minimum overpressure available.
Containment ourpressure was not credited in the calculation.
5.
When containment overpressure is credited in the calculation of available-NPSil, confirm that an appropriate containment pressure analysis was done to establish the minimum containment pressure.
. Not applicable.
'~, Unit 2 NRC Generic Letter No. 97 04 Page 3 Low liesd Safety Inlection (2 SIS'P21 A&Hh On Unit 2, these pumps do not draw from the containment sump. After the completion of the injection phase of response to the design basis LOCA, the low head safety injection pumps are shut off. Two of the four recirculation spray pumps take over the low head injection function.
liinh llend Safety Inlection (2CilS*P21 A,B&C):
These pumps operate in a " piggyback" mode after the system transfers from injection to recirculation.
2.
Identify the required NPSil and the available NPSil.
I Required NPSil approximately 22 feet (see UFSAR Table 6.3 1)
Available NPSil: 55.7 feet (bated on calculation 10080 DMC-53 0)
(Note: UFSAR Table 6.3 1 shows 29 feet available, but this is applicable only when drawing from the RWST.)
3.
Speelfy whether the current design basis NPSil analysis differs from the most recent analysis reviewed and approved by the NRC for which a safety evaluation was issued.
The UFSAR, on page 6.3 6, describes operation in recirculation, but gives no NPSil infonnation on that mode of operation. The above listed calculation was prepared to address concerns raised by NRC Infonnation Notice 88 74.
4.
Speelfy whether containment overpressure was credited in the calculation of available NPSil. Speelfy the amount of overpressure needed and the minimum overpressure availabic.
While the above listed NPSil value (55.7 feet) includes a conuibution from an assumed containment pressure of 11 psia and accounts for a water temperature of 120'F at the high head safety injection pump (the sump water is cooled prior to reaching the high head pumps), the containment pressure is not needed to assure that NPSil is met, Assuming a representative sump water temperature of 180'F and subtracting the containment pressure contribution above this vapor pressure,
- _ - -.__ _. _ =__
, Unit 2 NRC Generic Letter No. 97 04 Page 4 liinh llead Safety Inlection (2CilS*P21 A.B&C)(Continued):
leaves 47 feet of NPSil, still well above the minitium value. This shows that, in the " piggyback" mode of operation, the low head pump output pressure is more important than the containment pressure in assuring that the liigh llead Safety injertion Pump NPS11 requirements are met.
5.
When containment overpressure is credited in the calculation of available NPSil, confirm that an appropriate containment pressure antlysis was done to establish the minimum containment pressure.
No containment overpressure is required.
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FIGURE 6.3-10 AVAILABLE NPSH FOR LHSI PUMP PUMP SUCTION DER - MIN.ESF BEAVER VALLEY POWER STATION UNIT 1 UPDATED FINAL SAFETY ANALYSIS REPORT
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