ML20217N327

Part 21 Rept Re non-linear Oxygen Readings with Two (2) Model 225 CMA-X Containment Monitoring Sys at Bsep.Caused by High Gain Produced by 10K Resistor Across Second Stage Amplifier.Engineering Drawings Will Be Revised

ML20217N327
Person / Time
Site:	Brunswick
Issue date:	10/21/1999
From:	Khajavi R TELEDYNE ANALYTICAL INSTRUMENTS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-PT21-99 NUDOCS 9910280183
Download: ML20217N327 (4)

Text

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._e W TELEDYNE ELECTRONIC TECHNOLOGIES AnalyticalInstruments An Allegheny Teledyne Company g ->

16830 CHESTNUT STREET, CITY OF INDUSTRY, CA 917481020 P.O. BOX 1680. CITY OF INDUSTRY, CA 91749-1680 TELEPHONE: (626) 9344600 OR (826) 961-9221

. October 21,1999 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Subject:

10CFR Part 21 Report, Cxtainment Monitoring System Model 225 CMA-X

Reference:

Teledyne's Engineering Evaluation Letter, from K. Johns to R. Khajavi, Dated 5 October 1999 (Exhibit 1)

Dear Sir or Madam:

Teledyne Electronic Technologies, Analytical Instmments hereby notifies and submits a 10CFR Part 21 Report to the U.S. Nuclear Regulatory Commission (NRC) of a problem identified by the Carolina Power & Light Corporation and communicated to Teledyne Analytical Instruments on September 22,1999. We are not certain whether this event warrants 10CFR Part 21 Report. In our opinion, this problem does not introduce a substantial safet., hazard and it is detectable during the routine calibration, therefore, precluding its use. Nevertheless, Teledyne Analytical Instrument felt that it was prudent to advise the NRC and the affected Customers, as a minimum.

On September 22, 1999 Carolina Power & Light Corporation notified Teledyne Analytical utstruments that they were experiencing non-linear oxygen readings with two (2) Model 225 CMA-X Containment Monitoring Systems (oxygen application only) at the Bmnswick Nuclear Power Plant. This behavior was witnessed during their routine calibration when replacing an old fuel cell with a new fuel cell. In reviewing our product field performance records, Teledyne has not received any customer reports or advisory indicating tiie same non-linearity experience on ' Model 225 CMA-X Containment Monitor.

Teledyne's investigation (Exhibit 1) revealed that the non-linear response is caused by the high gain produced by the 10K resistor (P/N: R311) across the second stage amplifier. l This anomaly occurs if the fuel cell (oxygen application only) installed has an output I close to 50 microamps. To preclude recurrence, Engineering drawings will be revised to ,'

replace the 10K resistor with a 7.5K resistor (P/N: R406) which will reduce the gain by 25%. Testing was conducted and validated the effectiveness of corrective action. In addition, all afTected Customers will be advised on the Teledyne's corrective action.

rz 9910280183 991021 '

PDR ADOCK 05000324 '

S PDR Reference #: RK: 10-99-023 I

p' W TELEDYNE ELECTRONIC TECHNOLOGIES AnalyticalInstruments Date: September 21,1999 ""*"""'""*""""

l pubjec): 10CFR Part 21 Report, Containment Monitoring System Model 225 CMA-X Page 2 of 2 The following lists the customers planned for problem notification and corrective action:

-Carolina Power & Light -Bernische Kraftwerk AG

-Taiwan Power Co. -Vermont Yankee Nuclear Power Corp.

-Niagara Mohawk Power Corp. -Nucienor, Spain in summary, Teltdyne has ideatified the root cause, will revise the engineering drawings to reflect the planned cor ective action and notify affected customers no later than 10 November 1999.

Should further questions arise, please do not hesitate to contact Kim Johns, Nuclear Systems Engineer, at (626) 934-1611 or myself at (626) 934-1502.

Cordially, .

I Ray Khajavi, Director Quality Assurance l

l l-Reference #: RK: 10-99-023

"&TELEDYNE ELECTRONIC TECHNOLOGIES AnalyticalInstruments  ;

An Allegheny Tetedyne Company '

MEMORANDUM DATE: October 5,1999 I

TO: Ray Khajavi I

FROM: Kim Johns )

l CC: Al Pichelk, Ed Chu, Jeff Burks, Ron Downie

SUBJECT:

Engineering evaluation of problems reported in Carohna Power & Light Corp. E-mail dated September 22,1999 to J6 Burks.

On September 22,1999 an E-mail was received from Carolina Power & Light Corp. (CPLC) which stated that they were experiencing nonlinear O2 readings due to high 02 fuel cell outputs associated with the two (2)  !

Model 225 CMA-X Containment Monitoring Systems at the Brunswick Nuclear Plant. The nonlineer 02 readings were found during the routine calibration when replacing an old cell with a new cell. The worst caso non-linearity reported was 8%.

I l

Anal- s of the Suspected Defect I

The nuclear O2 fuel cell is Toledyne Electronic Technologies / Analytical Instruments (TET/AI) P/N C23831. l The fuel cc!1, for an ambient concentration of 20.9% O2, has a specihed output of 28 to 50 microamperes at atmospheric pressure and a temperature of 25#C. For recent manufacturing lots, the fuel cell outputs have been measured to be on the high end of the range between 40 to 50 microamperes. Fuel cells with an output close to 50 microamperes may cause the second stage amplifier of the O2 detector ampliher printed circuit board assembly (TET/Al P/N A238G0) to become saturated. This would make the O2 readings nonlinear.

The fuel cells in question at CPLC had lot numbers 214702,313077,313078 and 313079. Tests were performed on September 27 and 28,1999 to verify that the recent manufacturing lots of fuel cells had acceptable temperature characteristics. The fuel cells that were tested had lot numbers 313085,313086, and 313087. The tests showed that the recently manufactured ce!!s had identical temperature ,

l characteristics as the fuel cells that , vere originally qua!ified.

The gain of the 02 detector amplifier printed circuit board assembly was lowered by 25% by changing the j feedback resistor of the first stage amphher from 10,000 ohms to 7,500 ohms. The amphher was tested  ;

with a precision current source at 25 microamperes and at 50 microamperes. The test venhed that the amp?ifier performed within specification over this range.

Corrective Action Plan The non-linearity of the 02 reading wou!d norma!!y be found during routine calibration. In order to prevent this occurrence TET/Al recommends tnat the feedback resistor of the first stage amphher on the 02 detector ampliher printed circuit board assemb:y (TET/Al pin A23860) be changed from 10,000 ohms (TET/Al P/N R311) to 7,500 ohms (TET/Al P/N R406). This willlower the gain by 25% and prevent the second stage amphf.er fro n saturating for fue: cells with an output close to 50 microamperes. In addition the ga:n wi!! still be high enough for cets that have an output on the lower eqd of tne acceptable range of 26 m;croamperes Exhibit 1 Reference #: RKJ:991005A l

s ..

'/PTELEDYNE I MEMORANDUM ELECTRONIC TECHNOLOGIES 1 AnalyticalInstruments Aa ^iicoh ny Teiedyne company DATE: October 5. miq i

SUBJECT,:

• Nonlinear 02 Readings PAGE 2 OF 2 j

The following standard documents Mentify the location of the first stage amplifier feedback resistor as )

reference designator R1. l Document Number Description A23860 02 Control Unit Detector Amplifier P.C. Board Assembly i B24635 O2 Amplifier Schematic 1

The above documents are used on standard systems. If the systern is custom, the desciiption and  !

location of the resistor would be similar.

The 7,500 ohm resistor 4 available fully dedicated for use on class 1E safety related equipment as TET/A1 I l

P/N R400.

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l Reference #: RKJ.991005A