ML20198E279
| ML20198E279 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 12/30/1997 |
| From: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-97-04, GL-97-4, NUDOCS 9801090059 | |
| Download: ML20198E279 (5) | |
Text
, _ _.
Dave Marey Southern Nucleer We hetident s Operatsng Company (arley ho#ct PO tb 1795 i
4rmingt.am. Atatama 35?01
)
iol 205 992 $131 l
December 30, 1997 j
SOUTHERN COMPANY Enerrj to Sm'e Your %If" Docket Nos.:
50-348 10 CFR 50.54 50-364 U. S. Nuclear Regulatory Conunission A1TN.: Document Control Desk Washington, DC 20555 0001 Joseph M. Farley Nuclear Plant Response to Generic letter 97-04, " Assurance of Sufficient Net Posilirs_Sgtimilead for Emergettev Core Coolina and Containment Ileat Removalmres" Ladies and Ocotlemen:
NRC Generic Letter 97-04 roguested addressces to provide information pertaining to the ECCS and containment spray pump NPSil calculations for the recirculation mode._1hc 904ay actions have been completed by Southern Nuclear Operating Company (SNC), and the requested information is attached.
The 304y response was prmided by SNC letter dated October 27,1997.
As a result of this information request SNC has identified that changes and enha.ncements to the existing calculations need to be developod. These changes will correct errors and provide more accurate cale lations. SNC will complete this effort by June 1,1998 end will revise this submittal if there are cha. ges to the information prmided.
Respectfully submitted, fl )krt<
Dave Morey Sworn to and subscribed b lbre me this dQ_mlay of 1997
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NotaryPublic My Commission Erpires: fGW h&O/
t EWC:maf 97041228. doc 1
- Attachment-p) g ec:
Mr. L A. Reyes, Region 11 Administrater Mr. J, I. Zimmerman, NRR Senior Project Manager Mr. T. M. Ross, FNP Sr, Resident inspector lf llli ohll 9901090059 971230 PDR ADOCK 05000348 9
P PDR e
~.
ATTACllMENT Joseph M. Farley Nuclear Plant SNC Response to NRC Generic letter 97 04
" Assurance of Sulficient Net Positive Suction IIcad for Emergency Core Cooths and Containment lleat Removal Pumps" Licensees were requested to review the current design basis analyses used to determine the available NPSil for the emergency core cooling and containment heat removal pumps that meet either of the following criteria:
a.
Pumps that take suction from the containment sump or supprir ',i pool following a design-basis LOCA or secondary line break; or b.
Pumps used in " piggyback" operation that are necessary for recirculation cooling of the reactor core and containmer Licensecs were requested to provide the infomation outlined below in items 1,2, 3,4, and 5 for cach of their facilitics. Each item is addressed below.
1.
Specify the general methodology used to calculate the head loss associated with the ECCS suction strainers.
%c head loss associated with the ECCS suction strainers was determined by testing. A full scale model of Farley Nuclear Plant (FNP's) enntainment sump recirculation intakes was developed in the mid 1970's to evaluate the adcquacy of the intake design with regard to air-entraining and non-air-entraining vortices. A description of the model testing of the containmes.t sump recirculation intakes is found in FSAR Section 6C. Screen-grating losses for various configurations of blockage were determined from the use of piezameters. By means of the Farley specific containment sump recirculation intake model, extensive testing and data collection was conducted for numerous configurations and conditions to bound postulated post LOCA conditions Both FNP Unas employ four recirculation intakes. For Unit 1, there are two 14 inch diameter intakes for ECCS and two 10 inch diameter intakes for containment spray. One 14 inch intake for ECCS (referred to as intake 1) and one 10 inch intake for containment spray (referred to as intake
- 4) are cach enclosed by a separate screen-grating cage. He other 14 inch intake for ECCS and 10 inch intake for containment spray (referred to as intake 2 and 3, respectively) are enclosed by a shared screen-g.uting cage. For Unit 1, each of these intake configurations were modeled and tested. For Unit 2, a full scale model of a single 14 inch diameter intake mts tested.
1 s
Attachment 01-97 04 Dw maximum measured head losses across ths Unit I screer.$ rating cages under design flow conditions and with blockages as noted were as follows.
{
intake No.
Configuration Flow agpm) licad less (ft)
Blockage (%)
I R:lR 5900 0 09 63.7 2 and 3 RilR & CS 8950 0.14 64.2 4
CS 3050 0.04 69.4 FNP Unit 2 containment sump recirculation intakes are siindar is Unit 1, except cach intake is l
located within a separate screen-grating cage. Since there an. ' nbred screen-grating cages on Unit 2, the results for head losses across the screen grating casa from the Unit I model are bounding. These measured head losses are small when compared to the overall friction losses used in calculating the NPSli available ard in some cases were neglected in the calculations.
2.
Identify the required NPSil and the available NPSif.
ElEPump3 For Unit I, the required NPSil for Ac RiiR pumps is 17 ft at a calculated limiting condition of 4415 gpm fbr hot leg recirculation. The available NPSil is 20.78 ft.
For Unit 2, the required NPSil for the RilR pumps is 17 ft at a calculated limiting condition of 4400 gpm for cold or hot leg recirculation. The available NPSil is 19.06 ft Chargitut Pumoj At 670 gpm and with suction frort the RIIR pump discharge (recirculation mode), the NPS11 required for the Unit i or 2 charg.ng pump is 27 feet with an available NPSit of 95 ft. The available NPSli was determined based on a conservative configuration where one RilR pump provides ficw to two charging pumps at a combined flow of 1340 gpm. The recirculation configuration is bounded by the injection mode and therefore is not included in the design-basis calculations. The design basis is discussed in the response to item 3.
ContairunenLSprav Pumps lhe required NPSil for the Uni; I or 2 containnent spray pumps is 18 ft at 3050 gpm during recirculation. The available NI'Silis 19.3 ft for Unit I and 19.4 ft for Unit 2 2-L
e A.tachment GL-9744 i
3.
Specify whether the current design 4msis NPSH analysis differs from the most recent s
analysis reviewed and approved by the NRC for which a safety evaluation was issued.
The current design-basis NPSH analyses differ for the RHR and oxainment spray pumps. The differences are discussed below. He chargiag pump design-basis has not changed.
RilR Pumns
%n SER addressing the RHR NPSH analpes was issued for FSAR Amendments 40 (October 16, 1974) and 72 (March 7,1980). Updated crJculations were performed for modifications on the RilR pumps. He results of these analyses were incorporatert in FSAR Revision i1.
FSAR Amendments 40 and 72, note the NPSH available and required for the RHR pumps at a flow rate of 4200 gpm during cold leg recirculatma as follows.
Unit i Unit 2 NPSil available 20.6 A 19.7 A NPSil required 15.0 ft 15.0 ft Flow rate 4200 gpm 4200 gpm Time after accident Cold leg recire, Cold leg recire.
He results of subsequent calculations performed to address modifications to the RHR pumps are listed below. These values were included in FSAR Revision i1, Umt 1 Umt 2 NPSII availah!c 18.9 ft 17.4 ft NPSH requked 17.0 ft 15.8 A Flow rate 4415 spm 4350 gpm Time efler accident Hot leg recire.
Ilot or cold leg recire.
During prepasation for this re ponse, the analysis of the IGR NPSH was reviewed due to disparities in the results for the units. The results of the reanalysis are summarized below. The FSAR description of NPSH availtble and requi cd for the RHR pumps will be revised as needed.
Unit 1 Unit 2 NPSH available 20.78 ft 19.06 ft NhH required 17.0 ft 17.0 ft Flow rate 4415 gpm 4400 gpm Time after accident Hot leg recir:
Hot or cold leg recire.
Charninn Pumps -
ne FSAR describes the mos, limiting condition fer NPSH available. For the charging pumps, the end ofirdection mode is the most limiting condition. At the end of the injectica mode when suction from the RWST is terminated (low RWS T level), adequate net positive suction head is supplied from the containment sump by tle booster action of the RHR pumps. He design-basis NPSH required during injection mode for the charging pumps is 25 ft at 630 gpm. This deo::ption has 3-
~ Attachment
- GJ 97 f i
. ~. nptchanged and remains the current design-basis. 'Ihc NPSH required for the rce.irculation mode
' was calculated in preparation for this response. 'Ihe results are given in response to itcm 2, fM. W Sprav Pumos -
n FSAR Amendments 40 and 72 note the NPSH available and required for the containment spray pumps during reirculation as follows; Unit 1 UniL2 NPSH available 21.2 A
- 20.9 A -
. NPSH required.
17.5 A 17.5 A -
Flow rate -
3050 gpm -
3050 gpm i
' The current design-basis described in FSAR Revision 14 identifies the NPSH available and required as follows; Unt i Udt2 NPSH available.
19.3 A 19.4 A NPSH required 18.0 A 18.0 A Flow mte -
3050 gpm 3050 gpm 4, -
Specify whether containment overpressure (i.e., contain-t pressure above the vapor pressure of the sump or suppression pool fluid) was credited in the calculation of
- available NPSH. Specify the amount of overpressure needed and the minimum overpressure available.
Containment overpressure was not credited for either Unit in the calculation of available NPSH during timecirculation mode for the RHR, charging, a ul containment spray pumps.
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.
ltem 5 is not applicable to FNP, since containment overpressure was not credited in the calculation
- of available NPSH during the recirculation mode for the RHR, charging, and containment spray pumps for either Unit; I.
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