ML20012B262

Application for Amend to License NPF-6,changing Tech Specs to Revise Calibr Requirements for Linear Power Level,Cpc delta-T Power & CPC Nuclear Power Signals to Eliminate Unnecessary Calibrs

ML20012B262
Person / Time
Site:	Arkansas Nuclear
Issue date:	03/02/1990
From:	Carns N ARKANSAS POWER & LIGHT CO.
To:
Shared Package
ML20012B263	List: ML20012B262 ML20012B265
References
2CAN039006, 2CAN39006, NUDOCS 9003140080
Download: ML20012B262 (7)

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) Arkanens Power & Upht Company 425 Wer.1 Capio!

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> P O Dox551 Lee nxk AR 72203 Tel 501377 43X)

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March 2, 1990 l

2CANf39886 i  ?

U. S. Nuclear Regulatory Commission g Document Control Desk ,

l. Mail Station P1-137 Washington, DC '20555

SUBJECT:

Arkansas Nuclear One - Unit 2 -

Docket No. 50-368 License No. NPF-6 i CPC Calibration Requirements

• Technical Specification Change Request ,

i Gentlemen:

Attached for your review and approval are proposed Technical Specification changes revising the power calibration requirements for the Linear Power ,

level, CPC delta-T power and the CPC nuclear power signals, for AND Unit 2. '

The proposed changes will eliminate unne.cessary recalibre.tions and will

. result in more conservative calibrations of these signals with respect to -

the' calorimetric calculated power. Additionally'a time limit for declaring the char >:el inoperable is being added. l The proposed change has been evaluated in accordance with 10CFR50.91(a)(3) ,

using the criteria in 10CFR50.92(c) and has determined that these changes involve no significant hatards consideration. The bases for these (

determinations are included in the enclosed submittal. Although the circumbtar.ces u tr.is proposed amendment is not exigent or emergency, your t prorrpt review and hpproval is requested. l We request. that the effective date for this change be 30 days after NRC ,

issuance of the ameadment to allow for distribution and procedural revisions necessary to implement this change. J Very truly yours, )

N. S. Carn Vice President, Nuclear L NSC/1w 9

0k i Attachments / Enclosures 1 9003140080 900302 \\

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U. $. NRC Page 2 March 2, 1990 l

, cc: Mr. Robert Martin L U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 1000 l Arlington, TX 76011 NRC Senior Resident Inspector Arkansas Nuclear One - ANO-1 & 2 Number 1, Nuclear Plant Road 1 Russellville, AR 72801 Mr. Thomas W. Alexion NRR Project Manager, Region IV/ANO-1 U. S. Nuclear Regulatory Commission NRR Mail Stop 13-D-18 One White Flint North 11555 Rockville Pike Rockville, Maryland 20852 Mr. Chester Poslusny NRR Project Manager, Region IV/ANO-2 U. S. Nuclear Regulatory Commission NRR Mail Stop 13-D-18 One White Flint North 11555 Rockville Pike Rockville, Maryland 20852 Ms. Greta Dicus, Director

, Division of Radiation Control and Emergei.cy Management i Arkansas Department of Health 481E West Markham Street Litt'It Rock, AR 72201 l

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! STATE OF ARKANSAS -)

) SS COUNTY OF POPE )

I, N. S. Carns, being duly sworn, subscribe to-and say that I am Vice President, Nuclear for Arkansas Power & Light Company; that I have. full m- authority to execute this oath; that I have read the document numbered

- 2CANf39886 and know the contents thereof; and that to the best of my

knowledge, information and belief the statements in it are true, t

. .Y W - (

N. S. Carns i-i SUBSCRIBED AND SWORN T0 before me, a Notary Public in and for the

. County and State above named, this A day of efl _,

- 1990.

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Notary Public My Commission Expires:

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l ENCLOSURE' PROPOSED TECHNICAL SPECIFICATION AND RESPECTIVE SAFETY ANALYSES IN:THE MATTER OF AMENDING

_ LICENSE NO. NPF-6 ARKANSAS POWER & LIGHT COMPANY ARKANSAS NUCLEAR ONE. UNIT 2 DOCKET NO. 50-368 l

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. PROPOSED CHANGE l The proposed amendment will modify the power calibration requirements for l the Linear Power level, CPC delta-T and CPC nuclear power given in Technical

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Specification 3/4.3.1. Table 4.3-1 Note (2). The current Technical  !

Specification requires that when above 15% of RATED Power (Heat balance only), adjustment of the Linear Power level and the CPC addressable constant ,

multipliers for CPC delta-T and CPC nuclear power shall be made so that they -

agree with the calorimetric power calculation if the absolute difference is

>2% RATED THERMAL POWER (RTP). The proposed change will require  ;

L recalibration only if Linear Power, CPC delta-T power, or the CPC nuclear power are less than the calorimetric power (non-conservative).

I Specifically, when either the excore Linear Power or CPC powers are less .

than the calorimetric power by more than 1% RTP in the non-conservative l t direction, appropriate adjustments will be made so that the indicated excore  !

Linear Power and/or CPC delta-T and CPC nuclear power equal or exceed the calorimetric power calculation. Otherwise calibration adjustments will not be required, in addition a time specification to declare the channel inoperable is being added.

A revised copy of the affected page of the Technical Specifications is included in this Attachment. Bases Section 3/4.3.1 remains unchanged.

BACKGROUND The most accurate calibration of the excore Linear Power, CPC delta-T and CPC nuclear power is accomplished at high power levels (>80% RTP) where the main feedwater flow (which is an input to the secondary calorimetric r calculation) is more stable than at lower power levels. Additionally, since the feedwater flow differential pressure transmitter error is constant, it constitutes a smaller traction of the measured feedwater differential pressure signal at high power levels, thereby improving the secondary ,

calorimetric power accuracy.

Follosing a power reduction, the possibility exists that the excore Linear Power and CPC powers may differ significantly from the calorimetric power as a result of higher uncertainty in the secondary calorimetric power due to lower and more unstable feedwater flow rates. The curront Technical Specifict. tion requires a recalibration of the ercore Linear Power, CPC delta-T power and CPC nuclear power if they dif fer from celtarimetric power by more than 2% RTP, even if these indications are more conservative (higher) than the calorimetric power.

DISCUSSION The intent of the proposed Technical Specification change is to reduce the need for calibration of the Linear Power and CPC powers when these power indications are conservative relative to the calorimetric power calculation.

This will eliminate unnecessary changes to the PPS excore detector gain -

settings and the CPC addressable constants, especially changes that result in a non-conservative reduction in the Linear and/or CPC power indications, i

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L , Appropriate adjustments of the Linear Power and CPC power will be made however, if they are found to indicate a power level more than -1.0% RTP below the calorimetric power indication. Following adjustment, the excore i Linear Power and/or CPC powers will be verified to indicate a power level equal to or greater than the calorimetric power calculation.

! The proposed uodification of the permissible calibration tolerances will increase the probability that the power inputs to the plant protection e system and CPC algorithms are equal to or more conservative than the power indications which would result from calibrations performed using the present 12% RTP Technical Specification calibration tolerance. The proposed change is therefore conservative since it ensures that if protective action is required to mitigate the consequences of an Anticipated Operational Occurrence or Postulated Accident, it will occur at an actual power level which is lower than that allowed by the current specification. A time limit in which the channel is to be declared inoperable, if not calibrated, is also being added. The time limit of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is consistent with the intent of the specification to ensure that the channel is within tolerance within an acceptable period of time.

DETERMINATION OF SIGNIFICANT HAZARDS An evaluation of the proposed change has been performed in accordance with 10CFR50.91(a)(1) regarding no significant hazards consideration using the standards in 10CFR50.92(c). A discussion of those standards as they relate to this amendment request follows:

Criterion 1 - Does Not Involve a Significant Increase in the Probability or Consequences of an Accident Previously Evaluated The proposed change reduces the amount of ron-conservative error presently allowed in the PPS and CPC power indications and eliminates the requirement for channel calibration when the indications are already conservative settings does not increase the probability or consequences of any accident.

The proposed change also adds a time limit for channel calibration. The addition of this limit will not increase the probability or consequences of an accident previoJsly evaluated, as this is a new requirer.nent added to the specification. This requirement ensures that a channel deviation is correcied within a reasonable time frame to assure compliance with the assumptions of the safety antJyses.

Criterion 2 - Doas Not Create the Possibility of a New or Different Kind of Accident from any Previously Evaluated The proposed change does not involve any new or modified physical structures, systems, or components. Rather, it affects only the permissible power calibration tolerance limits and the time requirement for calibration of out-of-tolerance channels. Both of these effects are conservative relative to current explicit requirements and therefore will not create the possibility of a new or different kind of accident from any previously evaluated.

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, Criterion 3 - Does Fot Involve a Significant Reduction in the Margin of Safety The margins to safety are defined by those Design Basis Events which credit the high linear power level trip; the DNBR trip; and the local power density trip, as described in the ANO-2 Safety Analysis Report. By reducing the amount of non-conservatism allowed in the safety system power indications, and by not requiring adjustments of these indications in the non-conservative direction when they are already conservative, the margin to safety is increased rather than reduced. Furthermore, the addition of a requirement to declare a channel inoperable if not calibrated within the specified time limit places more restriction on the allowed operation of the systems and as such does not involve a significant reduction in the margin of safety. The time limit specified (24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) is consistent with the current requirements on channel comparison.

The Commission has provided guidance concerning the application of the f standards for determining whether a significant hazards consideration exists. The proposed amendment most closely matches example (ii) "A change that constitutes an additional limitation, restriction, or control not presently included in the technical specifications, e.g., a more stringent  :

surveillance requirement."

• Based on the above evaluation it is concluded that the proposed Technical Specification change does not constitute a significant hazards concern.

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