ML20148S605

Forwards Hydraulic Rept 12.5.487, NPSH - Rept of Sulzer Bingham Pump, & NSP Calculation CA 97-157, RHR Room Temp Response to GE Ltrs Gln 97-017 & Gln 97-019, in Response to 970630 Telcon by Tj Kim

ML20148S605
Person / Time
Site:	Monticello
Issue date:	07/02/1997
From:	Hill W NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20148S609	List: ML20148S605 ML20148S634 ML20148S653
References
TAC-M97781, NUDOCS 9707080270
Download: ML20148S605 (6)

Text

l Northem States Power Company Monticello Nuclear C1nerating Plant i 2807 West Hwy 75 t Monticello, Minnesota 55362 9637 l July 2,1997 l

US Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 I MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Request for Information Regarding MNGP License Amendment Dated June 19,1997 (TAC No. 97781)

The following responses are intended to address NRR questions concerning the subject license amendment which were communicated to NSP via a June 30,1997 telephone conversation by T.J. Kim, Monticello NRC Project Manager, to J. Beres, MNGP Licensing.

Please submit a copy of the vendor report for the Core Spray Pump.

Attached is a copy of Hydraulic Report: 12.5.487, "NPSH - Report of Sulzer Bingham Pump."

The following discussion addresses the basis for revising the core spray pump NPSHa curve.

The Net Positive Suction Head Required (NPSHa) curve for a pump is determined by manufacturer testing. The NPSHa for a pump at a specific flow rate is determined by throttling suction flow and observing a decrease in the total developed head. The Hydraulics Institute Standard requirement for determining NPSHa is an observed 3% decrease in total dynamic head. 1 I '

A review of the MNGP Core Spray pump test data from the original manufacturer, Bingham Pump Co., indicated that the NPSHa curves were based on a 1% degradation in total dynamic head. This pump test data was for a " witness test" by which the pump manufacturer g\

demonstrated specific purchase order requirements for flow, total developed head, and NPSHa.

The manufacturer was not performing a standard NPSH test per se to determine the minimum required NPSH. The witness test NPSHa curves, which are based on a 1% decrease in total dynamic head, are considered overly conservative with respect to the standard 3% decrease.

The Core Spray pump manufacturer, now Sulzer Bingham Pumps Inc., was retained to determine the minimum NFSHa for these pumps using the Hydraulics institute Standards. A 1/3/97 JEB 1/3/97 JEB J t \ LI CENSE \JOEL\LETTEks \ PHW' ECON . DOC 7 / 3 / 97 IlllillOlllillllfillllO!Illi gg70ggM8ga - * * ' # ' -

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. ' new NPSHa curve (# 2) is provided for the Core Spray pumps which is based on test data for these pumps in which there was a 3% decrease in total dynamic head. The curve is only valid for flow rates between 4,000 gpm and 5,300 gpm due to range of test data. For flow ratee less  ;

than 4,000 gpm, the original NPSHa curve was used to provide values for NPSHa.

As a precautionary measure, NSP also requested that Sulzer evaluate the operation of the pumps with less than the required NPSH. This additional effort required an evaluation of the similarity of the MNGP Core Spray pumps to the Quad Cities pump which was tested under degraded NPSH conditions. The attached pump report provides the results of these evaluations. Since the NPSHa value for the Core Spray pumps at maximum system flow could be satisfied by the containment pressure available for the short term accident scenario, the i evaluation of the pumps with less than required NPSH is not being utilized at this time. l By Exhibit E of the license amendment request, NSP revised the Duke Engineering and l Services calculation output to determine the required containment pressure necessary to assure I I

adequate NPSH for the B Core Spray pump. This revision used an NPSHa value for the B Core Spray pump determined from a pump curve for a Quad Cities RHR pump (Curve #26895). This was based on information from Sulzer Bingham Pump indicating that the NPSHa requirements were identical. The NPSHa value used to make that revision was 27 ft for a ' low rate of approximately 4300 gpm. In light of the new data, the previous NPSHa value of 27 ft at 4,300 i gpm is still valid as demonstrated by Curve #2 of the attached pump report. The NPSHa value, however, is now based on test data for the MNGP Core Spray pumps rather than similarity.

The test data for the Residual Heat Removal (RHR) pump NPSHa curves was reviewed, and there are no plans to develop new NPSHa curves for the RHR pumps. The containment pressure required to assure adequate NPSH for the Core Spray pumps bounds that required for the RHR pumps for the accident conditions evaluated in Exhibit E of the license amendment request. The existing NPSHa curves for the RHR pumps were used as inputs to the NPSH calculation of Exhibit E.

l Please submit a copy of the RHR room temperature calculation. i Attached is a copy of NSP Calculation CA 97-157, "RHR Room Temp Response to General .

Electric Letters GLN 97-017 and GLN 019." Some additional information from a separate I calculation is included with this calculation to clarify modeling techniques and assumptions. The production runs, which are voluminous, are not included. These runs and the referenced attachments are available for inspection on sia.

Pleasejustify the use of the 600 hp heat input for the 700 hp RHR pump motorin the above calculation.

Two separate studies validate the conservatism of this assumption. The actual operating electric horsepower (EHP) for each motor was recently measured, and the resulting BHP for each pump was calculated. All operating BHP values were found to be less than the rated value of 600 hp. In addition, the rated BHP, which was used in the calculatiori, is greater than the manufacturer's measured BHP at design operating conditions. The rated BHP value is used to 7/3/97 JEB Ja\ LICENSE \JOEL\ LETTERS \FtDNECON. DOC

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, ' determine the heat added. . Consequently the 600 hp assumption is conservative with respect to

! heat added.

t This letter contains no new NRC commitments.

Please contact Joel Beres, Licensing Engineer, at (612) 295-1436 if you require further information.

4 N Q1- --

kr William J. Hill Plant Manager Monticello Nuclear Generating Plant c: Regional Administrator-lil, NRC NRR Project Manager, NRC Sr Resident inspector, NRC State of Minnesota, Attn: Kris Sanda  !

Attachments:

Hydraulic Report: 12.5.487, "NPSH - Report of Sulzer Bingham Pump" NSP Calculation CA 97-157, "RHR Room Temp Response to General Electric Letters GLN 97- '

017 and GLN 019" i

7/3/97 JEB J 1 \LI CENSE \ JOE L\ LETTF.R S \ P HONECON . ICC