NG-06-0733, Response to Request for Additional Information Related to Request for Relief Concerning Flow Measurement for the Standby Liquid Control Pumps

Response to Request for Additional Information Related to Request for Relief Concerning Flow Measurement for the Standby Liquid Control Pumps

ML063190300
Person / Time
Site:	Duane Arnold
Issue date:	11/03/2006
From:	Vanmiddlesworth G Duane Arnold
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NG-06-0733
Download: ML063190300 (16)

Text

FPL Energy Duane Arnold, LLC 3277 DAEC Road Palo, Iowa 52324 FPLEne Duane Arnold Energy Center November 3, 2006 NG-06-0733 10 CFR 50.55a U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Duane Arnold Energy Center Docket No: 50-331 Op. License No: DPR-49 Response To Request For Additional Information Related To Request For Relief Concerning Flow Measurement For the Standby Liquid Control Pumps

References:

1) Letter dated September 28, 2006, "Request For Additional Information Related To The Request For Relief Concerning Flow Measurement For The Standby Liquid Control Pumps," (TAC NO. MD1 844)

2) Letter to NRC from G. Van Middlesworth, "Fourth Ten-Year Interval Inservice Testing Program Relief Requests," dated May 8, 2006 By letter dated September 28, 2006 (Reference 1), the NRC issued a request for additional information (RAI) related to the May 8, 2006 (Reference 2) request for relief concerning flow measurement for the Standby Liquid Control Pumps (Relief Request PR-03). Per discussions with the Staff on August 10, 2006, a response to this RAI is due within 30 days of receipt of the RAI. The RAI was received on October 5, 2006 (via e-mail). The requested additional information is contained in the Enclosure to this letter. Should you have any questions regarding this matter, please contact Steve Catron, Duane Arnold Energy Center Licensing Manager, at (319) 851-7234. This letter contains no new commitments or revisions to existing commitments.

JGa*Vn Middlesworth Site Vice President, Duane Arnold Energy Center FPL Energy Duane Arnold, LLC Enclosure cc: Administrator, Region Ill, USNRC Project Manager, DAEC, USNRC Resident Inspector, DAEC, USNRC 4L00

ENCLOSURE Response To Request For Additional Information Related To Request For Relief Concerning Flow Measurement For The Standby Liquid Control Pumps NRC Question 1 Please provide isometric diagram of the Standby Liquid Control (SBLC) System including details such as the length of piping and system components.

FPL Energy Duane Arnold Response to Question 1 The following diagrams of the Standby Liquid Control System are included in to this

Enclosure:

ISO-HCB-002-01 Rev. 8 FSK-03959 Rev. 9 FSK-3960 Rev. 8 FSK-3963 Rev. 1 FSK-3989 Rev. 2 FSK-3990 Rev. 2 FSK-3991 Rev. 2 FSK-3992 Rev. 4 FSK-3993 Rev. 5 FSK-3734 Rev. 16 NRC Question 2 The licensee stated that portable ultrasonic flow meters were installed on the common SBLC pump discharge piping to determine the practicality of using later technology ultrasonic flow meters to measure flow. The flow meter transducers were installed at three different locations on the discharge piping. However, each location resulted in significantly different measured flow rates compared to the other locations and the test tank level method. Please provide the data on the measured flow rates at different locations using the ultrasonic flow meters and compare them to those using the test tank level method.

FPL Energy Duane Arnold Response to Question 2 In March 2006, during the performance of Surveillance Test Procedure (STP)

"SBLC Pump Operability Test," portable ultrasonic flow meters were installed on the SBLC pump discharge piping to determine the practicality of using ultrasonic flow meters to measure flow per the ASME OM Code. The flowmeter transducers were installed at three different locations on the discharge piping (as identified on the drawings FSK-03959, FSK-3963, and FSK-3960). A vendor representative was on-site to facilitate proper installation and setup of the Page 1 of 4

transducers and flow meters. The pump flow rate calculated using the change in tank level method of the STP was 28.7 gpm for the "A" SBLC pump. The reference value for the "A" pump is 28.8 gpm. The flow rate from each subsequent test is compared to this value. Because of the simplicity of this test method, 28.7 gpm is considered the correct baseline value. Following are the results of flow measurement at each of the locations using the portable ultrasonic flow meters.

Location 1:

The transducers at location 1 were originally set up in direct measurement mode.

(In direct measurement mode the transducers are placed on opposite sides of the pipe and a signal is passed through the pipe and fluid from one transducer to the other in both directions.) This mode, which was recommended by the manufacturer, did not provide adequate signal strength. The flow meter was then reprogrammed and the transducers were reconfigured for reflective mode. (In reflective mode both transducers are installed on the same side of the pipe and the signal from each transducer is reflected off the opposite side of the pipe and into the other transducer.) This mode indicated adequate signal strength. Initial flow rate in this configuration was steady at 28.2 to 28.5 gpm. After several minutes running in this configuration the vendor representative added additional UT couplant to the transducer that had been moved earlier. Flow rate increased to 30 gpm following addition of couplant. The vendor representative then programmed into the flow meter the "T" in the flow path just upstream of the transducer. Resulting flow rate was about 31.2 gpm. No more changes were made to this flow meter.

Location 2:

The transducers for the flow meter mounted at location 2 were mounted and programmed for direct measurement. Following pump start, this flow meter read erratically between 20 and 26 gpm and occasionally indicated a faulted condition. It was judged that due to the location (only a few feet from where flow enters the test tank and on the same elevation and down stream of the throttle valve) there may be air in the pipe which caused the erratic flow rates and faults. The transducers were then moved to Location 3.

Location 3:

At location 3, the transducers were mounted for measurement in the reflective mode.

Flow measured in this configuration was 27.5 gpm. In the judgement of the vendor representative, the lower flow rate was the result of the elbow just downstream of the transducers.

As can be seen from the flow variances between the location and the tank level method, the measured flow variance is much higher than would be desirable or acceptable. The flow variance is caused by the tight piping routing and minimal straight runs of piping.

NRC Question 3 Paragraph ISTB-351 0(a) of the American Society of Mechanical Engineers Operation and Maintenance Code specifies that the flow rate determination shall be Page 2 of 4

accurate to within +/-2 percent actual. Please provide the flow rate determination methodology that meets this Code requirement. Also, include the correlation curve conversion from test tank level to water volume.

FPL Enerqy Duane Arnold Response to Question 3 SBLC pump flow rate is determined by measuring the time it takes for each pump to pump down at least 20 inches of test tank level. A graduated sight glass is used to determine tank level. A stopwatch, which is started when the meniscus passes through an inch mark on the sight glass and stopped when the meniscus passes through a second inch mark after at least 20 inches, is used to measure time. The change in tank level (in inches) is then divided by the elapsed time and multiplied by a conversion factor of 294 (gal-sec)/(in-min). This conversion factor is based on the inside diameter of the test tank (38 inches) and is calculated as follows:

7r 2 4 (38"in)2in ft )3 7.48.gal 60sec = 2 9 4 .5 5 5 gal sec in-of-tank " i ft min in-min The stopwatch used during this test has an accuracy of +/-0.2 sec/hour with typical elapsed time of 205 seconds. This corresponds to an accuracy in gallons per minute of:

.2.sec hr 20in gal'sec - 1597 10- 3 gal 2 94 5 5 5 hr 3600.sec 205.sec in-min min Readability of the test tank sight glass is assumed to be +/-0.1 inches when the stopwatch is started and stopped. This corresponds to an accuracy in gallons per minute of:

.1.in 2 9 4 .5 5 5 .gasec 0.144 gal 205.sec in-min min Total accuracy of SBLC flow measurement is as follows:

ASBLCF :V j(.O015gpm)2 + 2(.144gpm)2 ASBLCF = 0.204gpm In percent of the reference value this corresponds to:

.204gpm - 0.708%

28.8gpm Page 3 of 4

Since the portion of the test tank where the flow measurement is taken has a straight wall, the volume of water per inch of tank does not change as tank level changes.

Therefore, the correlation curve of tank level versus tank volume would be a straight line. This correlation curve is not currently available. The change in level over measured time will be converted to flow rate using the formula (with the conversion factor of 294 (gal-sec)/(in-min)) as described in the original relief request submitted on May 8, 2006, and therefore, a correlation curve is not required. The correlation in terms of tank volume to level is 4.91 gal/inch. The tank level gage is 36 inches long, which allows for approximately 6 minutes of measured flow. Since the SBLC pumps are positive displacement pumps, suction and discharge parameters do not impact flow, and therefore, a minimum pump run time prior to testing is not required.

Page 4 of 4

Attachment To Enclosure For Response To Request For Additional Information Related To Request For Relief Concerning Flow Measurement For the Standby Liquid Control Pumps This Attachment contains the following diagrams:

ISO-HCB-002-01 Rev. 8 FSK-03959 Rev. 9 FSK-3960 Rev. 8 FSK-3963 Rev. 1 FSK-3989 Rev. 2 FSK-3990 Rev. 2 FSK-3991 Rev. 2 FSK-3992 Rev. 4 FSK-3993 Rev. 5 FSK-3734 Rev. 16 10 pages follow