ML20154E866

Provides Addl Info Per 980819 RAI Re NRC GL 97-04, Assurance of Sufficient Net Positive Suction Head for ECC & Containment Heat Removal Pumps

ML20154E866
Person / Time
Site:	San Onofre
Issue date:	10/05/1998
From:	Rainsberry J SOUTHERN CALIFORNIA EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-97-04, GL-97-4, TAC-MA0040, TAC-MA0041, TAC-MA40, TAC-MA41, NUDOCS 9810090010
Download: ML20154E866 (3)

Text

il l h SDUIHE RN CAL H ORMA -  !

B" ' EDISON * "'

'"", Plant Licensing Manager An EDISON INTERNATIOM4l* Company e ,.

October 5, 1998 U.S. Nuclear Regulatory Commission

-ATTN: Document Control Desk Washington, D.C. 20555-0001 l

Gentlemen: - j

Subject:

NRC Generic Letter 97-04: Assurance;of Sufficient Net Positive Suction Head for Emergency Core Cooling and_ Containment Heat Removal Pumps  !

San Onofre Nuclear Generating Station Units 2 and 3 (TAC Nos.  !

MA0040 and MA0041)

References:

1) August 19, 1998 letter from James W. Clifford (NRC) to Harold l B. Ray (SCE),'

Subject:

Request for Additional )

Information - San Onofre Nuclear Generating Station Units 2 and 3:(TAC Nos. MA0040.and MA0041) j

2) January 2, 1998 letter from J. L. Rainsberry (SCE) to Document Control Desk (NRC),

Subject:

NRC Generic Letter 97-04: Assurance of Sufficient Net Positive Suction Head for Emergency Core Cooling and Containment Heat Removal Pumps, San Onofre Nuclear Generating Station Units 2 and 3 This letter provides the additional information requested in Reference l' ,

concerning NRC Generic Letter (GL) 97-04. This information confirms the l adequacy of- the net positive suction head (NPSH) available for emergency core

. cooling and containment heat removal pumps at San Onofre Units 2 and 3. In addition to the information requested in Reference 1, a correction to ,

' Reference 2, Southern California Edison's (SCE's) initial response to GL  !

97-04, is provided below. The NRC questions in Reference 1 and SCE responses are the following: {

NRC Question 1:

What is the maximum sump temperature assumed in the net positive suction head (NPSH) analysis?  ;

SCE Response: \g The maximum sump temperature assumed in the NPSH analysis (Calculation M-0012-010) is 270 degrees F.

San Onofre Nuclear Generating Station P. O. Box 128

,o.

UiU( u) hoh San Clemente. CA 92674 0128 ,

9810090010 981005r  !

PDR ADOCK 05000361 P POR

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!' - Document Control Desk  ;

NRC Question'2:

Tables 1, 3, and 4 in the GL response (Reference 2) list the NPSH i l required for the containment spray pumps as 13 feet. However, the  !

flowrate provided in Tables 1 and 3 is 2200 gpm whereas the flowrate in

! Table 4 is 2500 gpm. Explain'why the NPSH required did not increase  !

with the 300 gpm increase in flow.

l SCE Responset for clarification,' the flowrates provided in Reference'2 Tables 1. and 4- f are 2500 gpm (runout flow), and the flowrate in Table 3 is 2200 gpm i

! (worstcasedesignflow). l i

L The data provided in Tables 1 and 4 were taken from the NPSH calculation ,

of record, M-0012-01D, which states that the NPSH required for l Containment Spray pumps at runout flow of 2500 gpm is-13.0 ft. A review '

of the manufacturer's certified test' curves confirmed that three of the '

l four containment spray pumps (there are two at each unit) were bounded by the data presented in the calculation. For three of these pumps, the  :

NPSH required 9 2500 gpm is equal to or less than 13.0 ft. However, the  !

( remaining pump (2P012) requires 13.0 ft. NPSH 9 2200 gpm and 14.0 ft. .!

NPSH 9 2500 gpm. This difference is not significant due to the large margin; NPSH available is 24.5 ft. The NPSH calculation of record,  ;

M-0012-01D, is an original Bechtel calculation, issued November 13, i

1980. SCE has added a note to the calculation documenting that 2P012 l l: requires 14.0 ft. NPSH 9 2500 gpm.  !

NRC Question 3: l l Have there been any other revisions to the NPSH calculations.Other than ]

those discussed in response to question 3 of the subject Generic Letter? '

h SCE Response.

The NPSH calculation of record to date (M-0012-01D) has not been revised j other than as discussed in the response to question 3 in Reference 2 and '

< addition of the note as stated in the response to question 2 above. A l design change package (DCP-2(3)-6863.0SN) was issued in 1993 to enable the use of the Containment Spray pumps for.. Shutdown Cooling or Spent Fuel Pool. Cooling. This design change added a 16"x10" weldolet in the suction of the Containment Spray pumps. Since Containment Spray flow from the Refueling Water Storage Tank or the Emergency Safety Features 1 Sump.is straight through the run of this connection, the change was i

!. considered to have a negligible impact on the NPSH calculation, and no l

[ changes were made.

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fL - . . . . ._

1 l

j. Document Control Desk  !

(. .

Correction to Reference 2:

Reference 2 referenced two calculations: M12.1D and N-0024-006. The actual calculation numbers are M-0012-010 and N-0240-006, respectively.

l-If you have any questions or would like additional information, please let me j know.

q-l Sincerely, l

, s a

i

/ l

\

l cc: E. W. Merschoff, Regional Administrator, NRC Region IV l J. A. Sloan, NRC Senior Resident Inspector, San Onofre Units 2 & 3 l.

J. W. Clifford, NRC Project Manager, San Onofre Units 2 and 3  ;

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