ML20236N635

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Responds to 980513 Request from Duquesne Light Co to Provide Written Interpretation of Beaver Valley Power Station,Unit 1 & 2 TSs Requirements for Channel Calibration of Rtds & Thermocouples
ML20236N635
Person / Time
Site: Beaver Valley
Issue date: 06/05/1998
From: Beckner W
NRC (Affiliation Not Assigned)
To: Capra R
NRC (Affiliation Not Assigned)
Shared Package
ML20236J990 List: ... further results
References
FOIA-98-155 NUDOCS 9807150200
Download: ML20236N635 (3)
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Text

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g k UNITED STATES t! ) NUCLEAR RESULATORY COMMISSION

  • WAsHINGfoN, D.C. 300e6 4001

,y, June 5, 1998 MEMORANDUM: Robert A. Capra Project Directorate,12 y

Division of Reactor Projects, NR D /Jr FROM: William D. Beckner, Chief . M Technical Specif' cations Branch Associate Director for Projects, NRR

Subject:

REQUEST FOR NRC INTERPRETATION - TECHNICAL SPECIFICATION CHANNEL CALIBRATION OF RTDS AND THERMOCOUPLE By letter dated May 13,1998, Duquesne Ught Company (licensee) requested that the Office of Nuclear Reactor Regulation provide a written interpretation of Beaver Valley Power Station (BVPS), Unit No.1 and No. 2 technical specifications (TS) requirements. The request is to clarify testing required by the definition of a channel calibration for instrument loops containing I resistance temperature detectors (RTDs) and thermocouple sensors. In response to your request, the staff evaluated the BVPS TS and prepared the following TS interpretation to assist in clarifying BVPS TS testing requirements.

The staff notes that the licensee letter references improved Standard Technical Specifications (STS) of NUREG-1431 as supporting their proposed interpretation of the current Technical Specifications (CTS) definition of a channel calibration. The current BVPS TS channel calibration definition is as follows:

"A CHANNEL CAUBRATION shall be the adjustment, as necessary, of the channel so that it responds within the required range and accuracy to known values of the parameter which the channel monitors. The CHANNEL C.*UBRATION shall encompass the entire channel, including the sensor (emphasis added) and alarm and/or trip functions, and shall include the CHANNEL FUNCTIONAL TEST. The CHANNEL CAUBRATION may be performed by any series of sequential, overlapping or total channel steps such that the entire channelis calibrated."

The licensee position is that it appears that CTS were not int' ended to require a calibration of RTD or thermocouple sensors. Rather, calibration of instrument channels with RTD or thermocouple sensors may consist of an in piece qualitative assessment of sensor behavior and normal calibration of the remaining adjustable devices in the channel. This position is based on language added to the improved STS channel calibration defirwtion noted in boldfaced type below concoming the complete definition.

"A CHANNEL CAUBRATION shall be the adjustment, as necessary, of the channel so that it responds within the required range and accuracy to known input. The CHANNEL CAUBRATION shall encompass the entire channel, including the required sensor, alarm,

Contact:

Carl Schulten (301) 415-1192 E-mail: CSSi@NRC. GOV 9007150200 900624 PDR FOIA UNNER3T98-155 PDR

s'

, R. A. Capra 2 June 5, 1998 interlock, display, and trip functions. Calibration of instrument channels with resistance temperature detector (RTD) or thw mocouple sensors may consist of an in place qualitative assessment of sensor behavior and normal calibration of the remaining a(justable devices in the channel. Whenever a sensing element is replaced, the next required CHANNEL CALIBRATION shall include an in-place cross calibration that compares the other sensing elements with the recently installed sensing element. The CHANNEL CALIBRATION may be performed by means of any series of sequential, overlapping calibrations or total channel steps so that the entire channel is calibrated."

Further, based on a favorable reply, the licensee intends to apply the improved STS interpretation to BVPS technical specifications that address RTDs and thermocouple.

Differences between TS requirements for channel calibrations based on CTS definitions and testing based on improved STS definitions are acknowledged to exist. However, when a surveillance test is done to comply with the current license then testing requirements are explicitly defined by CTS, including any related TS defined terms. Therefore, the staff interpretation of BVPS channel calibration TS is that TS require testing to include RTD or thermocouple sensors in the instrument channel and failure to test all components results in failure to comply with TS.

The staff cautions licensees that conversion of plant-specific TS to adopt improved STS both involves the addition of test requirements and TS limits and the relaxation of tests and the elimination of limits not required to meet the provisions of 10 CFR 50.36(c)(2)(ii). As can be seen from the improved STS definition for a channel calibration, a relaxation of sensor calib. ration is allowed unless RTD or thermocouple sensors are replaced. For these operations, in-place qualitative assessment of sensor behavior is not sufficient and the improved STS definition requires in-place cross calibration that compares the other sensing elements with the recently installed element. This element of the definition was omitted from the licensee discussion of improved STS requirements. NUREG-0800, Rev. 4, June igg 7, Branch Technical Position HICB-13,

  • Guidance on Cross-Calibration of Protection system Resistance Temperature Detectors", provides detailed guidance on RTD cross calibration procedures. Further, adoption of improved STS surveillance requirements (SR) for RTDs and thermoccupies includes additional testing requirements specif.ed in the SR notes such as verifying rate lag compensation for flow l from the core to the RTDs.

The staff reminds licensees that the Commission continues to place the highest priority on requests for complete conversions to the improved STS. Licensees using license amendments to adopt portions of the improved STS to existing technical specifications should adopt all related requirements, as applicable, to achieve a high degree of standardization and consistency.

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,, R. A. Capra 2 June 5, 1998 interlock, display, and trip functions. Calibration of instrument channels with resistance temperature detector (RTD) or thermocouple sensors may consist of an in-place qualitative assessment of sensor behavior and normal calibration of the remaining adjustable devices in the channel. Whenevar a sensing element is replaced, the next required CHANNEL CALIBRATION shall include an in-place cross calibration that compares the other sensing elements with the recently installed sensing element. The CHANNEL CALIBRATION may be performed by means of any series of sequential, overlapping calibrations or total channel steps so that the entire channel is calibrated."

Further, based on a favorable reply, the licensee intends to apply the improved STS interpretation to BVPS technical specifications that address RTDs and thermocouple.

l Differences between TS requirements for channel calibrations based on CTS definitions and testing based on improved STS definitions are acknowledged to exist. However, when a i surveillance test is done to comply with the current license then testing requirements are I

explicitly defined by CTS, including any related TS defined terms. Therefore, the staff interpretation of BVPS channel calibration TS is that TS require testing to include RTD or thermocouple sensors in the instrument channel and failure to test all components results in failure to comply with TS.

The staff cautions licensees that conversion of plant-specific TS to adopt improved STS both

! involves the addition of test requirements and TS limits and the relaxation of tests and the elimination of limits not required to meet tha provisions of 10 CFR 50.36(c)(2)(ii). As can be seen from the improved STS definition for a chaonel calibration, a relaxation of sensor calibration is allowed unless RTD or thermocouple sensors are replaced. For these operations, in-place qualitative assessment of sensor behavior is not sufficient and the improved STS definition requires in-place cross calibration that compares the other sensing elements with the recently i installed element. This element of the definition was omitted from the licensee discussion of l improved STS requirements. NUREG-0800, Rev. 4, June 1gg7, Branch Technical Position HICB-13, " Guidance on Cross-Calibration of Protection system Resistance Temperature Detectors", provides detailed guidance on RTD cross calibration procedures. Further, adoption of improved STS surveillance requirements (SR) for RTDs and thermocouple includes additional i testing requirements specified in the SR notes such as verifying rate lag compensation for flow

,l from the core to the RTDs.

The staff reminds licensees that the Commission continues to place the highest priority on requests for complete conversions to the improved STS. Licensees using license amendments to adopt portions of the improved STS to existing technical specifications should adopt all related requirements, as applicable, to achieve a high degree of standardization and consistency.

l

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