ML20093G295

Special Rept:On 950606,determined That Waste Gas Analyzer & Monitors H Concentrations Being Operated Incorrectly.Range 3 Successfully Calibrated by Comparing Analyzer Readout to Grab Sample Results

ML20093G295
Person / Time
Site:	Sequoyah
Issue date:	10/11/1995
From:	Shell R TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9510190011
Download: ML20093G295 (4)

Text

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13 Bl4 Tennessee Valley Avtbonty, Post Offce Box 2000, Soddy Daisy. Tennessee 37379 1

October 11,1995 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk .

Washington, D.C. 20555 s Gentlemen:

in the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328

. SEQUOYAH NUCLEAR PLANT (SON) - UNITS 1 AND 2 - FACILITY OPERATING LICENSES DPR-77 AND DPR 79 - TECHNICAL SPECIFICATION (TS) 3.3.3.10- SPECIAL REPORT 95-07 The enclosed special report provides details concerning the calibration of the waste gas analyzer. An earlier problem with the operation of the instrument, which was discussed in detail in LER 50-327/95006, resulted in a logic change being implemented. Previously, the alarm required both oxygen and hydrogen to exceed their respective setpoints before the alarm was initiated. The logic was reconfigured such that the hydrogen input is always energized. Calibration of the instrument was required following this logic change.

This special report details the issues that delayed this calibration.

This report is being submitted in accordance with TS 3.3.3.10 Action Statement (b).

This report was originally signed on September 1,1995. However, as the result of an administrative error, distribution of this report did not occur.

If you have any questions regarding this submittal, please telephone S. D. Gilley at (615)843-7427.

Sincerely, s

. R. H. Shell SON Site Licensing Manager Enclosure cc: See page 2 1"/0CC0

'9510190011 951011 \\

PDR ADDCK 05000327 )

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,a' U.S. Nuclear Regulatory Commission l

- Page 2 l October 11,1995' cc (Enclosure):

Mr. D. E. LaBarge, Project Manager U.S. Nuclear Regulatory Commission One White Flint,-North 11555 Rockville Pike Rockville, Maryland 20852-2739 ~

'NRC Resident inspector -

Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379-3624 Regional Administrator U.S. Nuclear Regulatory Commission Region ll 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323-2711 i

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i i~ ENCLOSURE i

l SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 SPECIAL REPORT 95 07 l

4 Descriotion of Condition On June 6,1995,it was determined that the waste gas analyzer (WGA) that monitors j hydrogen (H2 ) concentrations was being operated incorrectly. The alarm was supposed

to initiate for the condition where both the oxygen and hydrogen exceeded their.

respective -setpoints. 'The hydrogen monitoring portion of the analyzer was being

~ routinely operated on Range 3, which caused the setpoint calibration to be inaccurate.

In order to correct this deficiency, the logic was reconfigured such that the hydrogen F input to the alarm was always energized. This logic change allowed the instrument to

be used on the Range 3 scale to monitor hydrogen concentrations and still maintain the required alarm function in compliance with technical specifications (TSs). This change required the calibration of Range 3. While the calibration was being completed, the TS calibrated oxygen analyzer portion of the WGA was being used to ascertain the oxygen i concentrations. The calibration effort for Range 3 of the H2 analyzer was delayed for j several reasons.

a l During the initial attempt to calibrate the instrument, a temperature switch was not operating. A new switch was installed, but the new switch also failed to operate properly. A third switch had to be procured and installed. Following the installation of this third switch, the calibration process was able to be completed. After the steps for calibration had been completed, the results indicated that the voltage division j methodology used to calibrate the instrument did not yield accurate readings. Following 4 this determination, the calibration was completed by manually adjusting the Range 3

settings to coincide with the H, concentration levels as determined by grab samples. This j was an unusual circumstance where relatively high concentrations were being analyzed; i therefore, the grab samples had to be diluted to a much greater degree than normalin

] order to be able to determine the hydrogen concentration. Dilution was necessary because the instrument used to determine the concentration level was only capable of

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determining levels below 5 percent. Therefore, the sample had to be diluted until the

, concentration level was below 5 percent so that it could be measured. At these high dilution factors, the results are more sensitive to slight variations in the amount of diluting agent used. In some cases, variations between consecutive grab samples were not reflected in the corresponding analyzer readouts. Esen though the grab sample results ,

were within the acceptance criteria, additional attention was focused on the dilution methodology, which resulted in the reduction of the variation in grab sample results. As a result, Range 3 was successfully calibrated by comparing the analyzer readout to grab i sample results.

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" -2 Cause of Condition The cause for the delay in returning the analyzer to service was the time required to obtain, install, and test parts that f ailed to operate properly. Delays were also incurred '

as a result of problems with the voltage division methodology and later because of the

evaluation of variations that were introduced into the grab sample as a result of the high dilution factors.

Corrective Action in accordance with Limiting Condition for Operation 3.3.3.10 Action Statement (b), this special report is being submitted to explain the delays in returning the WGA to service.

Corrective actions were completed, and the WGA was declared operable on August 26, 1995.

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