NRC-95-0034, Submits Response to Insp follow-up 95002-01 & 95002-02 That Concerns Use of Ref Curves on SR Pumps to Determine If Pump Hydraulic Performance Was Acceptable

Submits Response to Insp follow-up 95002-01 & 95002-02 That Concerns Use of Ref Curves on SR Pumps to Determine If Pump Hydraulic Performance Was Acceptable

ML20082E225
Person / Time
Site:	Fermi
Issue date:	04/07/1995
From:	Mckeon R DETROIT EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-95-0034, CON-NRC-95-34 NUDOCS 9504110150
Download: ML20082E225 (8)

Text

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Robert McKeon

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April 7,1995 NRC-95-0034 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington D. C. 20555

References:

1) Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43

2) NRC Inspection Report 95002 dated February 10,1995

Subject:

Response to Insoection Follow-un Iteme 95002-01 and 95002-02 Enclosed is Detroit Edison's response to Inspection Follow-up Jtems (IFI) 95002-01 and 95002-02. IFI 95-002-01 ' concerns the use of reference curves on safety-related pumps to determine if pump hydraulic performance was acceptable. IFI 95002-02 concerns the method for determination of pump differential pressure for the RHRSW pumps.

The following commitments, as noted in response to IFI 95002-01, are being made in this letter:

1. New and revised relief requests will be submitted by July 14,1995 for NRC review and approval.

! 2. Implementing procedures for fixed point reference values will be revised by July 21,1995.

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' NRC-95-0034 Page 2 0f 3 -  ;

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. If you have any questions, please contact Jim Martin, Compliance Engineer, at (313) 586-4225.

Sincerely, M# l

Enclosure:

cc: T. G. Colburn ,.

J. B. Martin .

M. P. Phillips '

A. Vegel ,.

Region III P

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NRC-95-0034 Page1 INSPECTION FOLLOW-UP ITEM 95002-01 The licensee was using pump reference curves on all the safety-related pumps to determine if the pump hydraulic performance was acceptable without submitted or approved relief requests. The use of pump reference curves for IST was not in accordance with the Code requirements and, therefore, relief was required. The Fermi 2 IST program identified 34 safety-related pumps in 9 separate systems that used reference curves.......The licensee should provide a schedule that details the implementation of the code requirements or the submission of relief requests for each system.

DETROIT EDISON RESPONSE TO IFI 95002-01 All pumps in the IST program have been reviewed to determine which pumps could be tested at a fixed reference in full compliance with ASME Section XI Code, and which will remain being tested via a variable refereo e, thus requiring a relief request to be submitted. Based on this analyFis, actions necessary to bring the IST pump testing program into conformance with current regulatory standards will include the submittal to the NRC of new and revised relief requests for those pumps which cannot be practically tested in strict compliance with ASME Section XI Code requirements. The new and revised relief requests will be submitted to the NRC by July 14,1995 for review and approval.

New relief requests will be issued for each of the following:

• RHR pumps

• HPCI pump

• EECW pumps

• Diesel Generator Service Water Pumps

• CCHVAC Chill Water Pumps.

Relief requests PR-6 and PR-7, for Core Spray (CS) and Residual Heat Removal Service Water (RHRSW) pumps respectively, will be revised and resubmitted.

Both RHRSW and CS pumps will continue to be tested in 2 pump test configuration. Justification for this position will be provided in the associated relief requests.

Implementing procedures for the Diesel Fuel Oil Transfer Pumps and EESW Pumps will be revised to implement fixed point reference value testing by July 21,1995.

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Testing for those pumps for which reliefis being requested shall continue to be performed using the current methodology and procedures until these Relief Requests are approved. Upon notification of approval the affected documents will be revised.

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p INSPECTION FOLLOW-UP ITEM 95002 I The licensee's determination ofinlet pressure for the RHRSW pumps did not conform to the basis for relief and alternate testing in approved relief request -  :

PR-3. These were vertical line shaft pumps that take suction from the intake bay, -l which made the measurement ofinlet pressure impractical.' The relief request stated that the hydrostatic head at the pump inlet would be calculated based on the pump reservoir level.

The RIIRSW pump test data indicated that the licensee was not calculating inlet pressure to determine pump differential pressure (d/p). The licensee stated they were calculating what they described as " suction lift," which was the difference in height between the reservoir level and the height to the pump discharge .

pressure gauge. Although the " suction lift" calculation appeared to provide a j

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trendable value of d/p, it did not appear to be the correct method for calculating the actual pump d/p. The licensee stated during the inspection that they would submit additional information concerning the validity of the RHRSW inlet pressure calculation.

DETROIT EDISON RESPONSE TO IFI 95002-02 Detroit Edison believes that the current method being used to calculate differential pressure is technically correct and in compliance with ASME Section '

i XI Code requirements. The following information is being provided as further justification for the current methodology being applied.

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1. 1980, W'81 ASME Section XI, IWP Requirement: -

IWP-4240 states: "The differential pressure across a pump shall be determined by use of a differential pressure gauge or a differential pressure transmitter that provides direct measurement of pressure difference, or by taking the difference between the pressure at a point in the inlet pipe and the presure at a point in the discharge pipe."

2. Relief Request PR-3 The alternate testing section states: "The inlet pressure measurement will be based on reservoir level."

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3. TechnicalJustification The Fermi program uses the difference between discharge pressure at the second stage impeller and inlet pressure (reservoir level above the suction) which is

- consistent with PR-3 in that the inlet pressure measurement is based on reseivoir -

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. level. As such, the discharge pressure gauge reading, Pd; must be corrected for the static head of water between the discharge of the pump second stage impeller and the elevation of the gauge. This methodology treats the shaft housing up to -

the discharge pressure gauge, as discharge line.

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Attachment to NRC-95-0034 Page 4 l- ,

The Fermi 2 testing method takes into account the variable reservoir level and provides for enhanced degradation detection capability. This testing methodology is equivalent to the Code required testing methodology based on the following:

P #

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Reservoir s,

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l Level '

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P )

P

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RHRSW Pump l I

Figure No. I j RHRSW Pump Testing Configuration

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h5 j AP = P - Pi AP = P - Pi )

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Where: P = Pump discharge pressure as First: P dmust be converted to P in units 1 stated in IWP-4240, psig of psig:

Pd= discharge pressure gage reading.

Since the gage is not located at the l .

point where discharge pressure is to l be measured (Ref. point P),it must  !

be corrected for the elevation distance between Pd and P. This is corrected by adding the static water -I head to the gage reading. Thus: ,

P = Pd + H + h. j i

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, H and h are normally measured in~

. feet of water and must be converted -

Y to psi, since the gage reads in psig, pounds per square inch. I foot;of.

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wateris equal to 0.4335 psi (ref.

Pump Handbook).

The above is then expressed as:

P =Pd+ [ H + h ]x0.4335 psig-Pj = Inlet Pressure as stated in Second: Pi must be obtained from IWP-4240, psig reservoirlevel above the pump .

suction:

Pi = Inlet Pressure. Inlet Pressure is -

determined for a deep draft pump such as the RHRSW pumps by - .

measuring the total static height of -

water above the pump inlet. Thus, h is measured in feet and also mbst be '

converted to psig. This is what was -

specified in Relief Request PR-3.

The distance between the suction and the reservoirlevelis converted to psig using the conversion factor-above.

Pf = [ h ]x0.4335 psig Substituting these two terms into the -

original equation, AP = P- Pi yields:

AP = Pd+ [ H + h ]x0.4335 psig

- [ h ]x0.4335 psig Combining terms:

AP = Pd + [ H + h - h ]x0.4335 psig AP = Pd + [ H ]x0.4335 psig Therefore, AP = P - Pi is equivalent to: AP = Pd+ [ H ]x0.4335 psig .

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[ H ]x0.4335 psig is the term used in the RHRSW surveillance procedure and is :

, identified as Lift, psig. This term is added to.the pump discharge pressure gage reading to obtain AP.

4.- References Consulted Pump Handbook, edited by I. J. Karassik, W. C. Krutzch and W. H. Fraser, and published by McGraw-Hill Book Company,01976 (Figure 27 of Section 14 provides additional suppon for this methodology)

5. Conclusion y The Fermi 2 methodology used for determing Differential Pressure for the L RHRSW Pumps complies with both ASME Section XI, Subsection IWP, and with the Fermi 2 IST Program, Pump Relief Request PR-3. In addition, the current testing methodology takes into account fluctuating reservoir level in a manner that provides a more accurate assessment of pump degradation.

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