ML20082C658

Proposed Tech Specs Re Quadrant Power Tilt Ratio

ML20082C658
Person / Time
Site:	Comanche Peak
Issue date:	04/03/1995
From:	TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:
Shared Package
ML20082C650	List: ML20082C640 ML20082C658
References
TXX-95098, NUDOCS 9504070101
Download: ML20082C658 (4)

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4 ATTACHMENT 2.T0 TXX 95098 i

AFFECTED TECHNICAL SPECIFICATION PAGES l

(NUREG 1468) l Pages from NUREG 1431, B3.2 45 through B3.2 47 j

marked up for insertion into the CPSES Technical Specification BASES-d i.

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'Attachrent 2 to TXX 95098 QPTR 8324i Page 1 of 3 14 S E AT 'S" c,.. t.

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&dzi (continued) gross radial _ power distribution that requires an investigation and evaluation that is accomplished by examining the incore power distribution.

Specifically, the core peaking factors and the quadrant tilt must be evaluated because they are the factors that best characterize the core power distribution.

This re-evaluation is required to ensurethjt, befog creasing THERMAL POWER to above the limit of

, the reactor core conditions areconsd.;!-.

tent wi th ass tions in the safety analyses.

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If the QPTR has exceeded the 1.02 limit and a re-evaluation

( e h.5+I** 1 C*) of the safety analysis is completed and shows that safety requirements are amt, the excore detectors are recalibrated to show a zero QPT rior sin THERMAL POWER to above the limit of This is done to detect any subse igni cant s in QPTR.

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states that 7

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zerced out un4 4 4fter the re-evaluation of t

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the safety analysis has determined that core conditions at RTP are vi the safety analysis assumptions (i.e.,

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" 4 0 ^nce the flux tilt is zeroed out (i.e.,

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o.. tis performed), it is acceptable te return o ull power operation. However, as an added check that the core j

power distribution at" Rip is the safety fx_

uires analysis assumptions k[;a;n;d Fm*

verification that Fef are within their specified lielts within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of reaching RTP. As an added precaution, if the core power does not reach RTP within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, but is increased slowly, then the peaking factor surveillances must be performed within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of the time when the ascent to power was begun. These empletion Jimes y time i

ase THERMA 1.

are intended to allow a 7 ;;t ;.ga ncgff//*:t;whilenot POWER to above the limit o e..t (continued) w w

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" Attachment 2 to TXX 95098 l

Page 2 of 3 g 3.2.4 INSERT "3" Con 6 l

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permittityl-the core to remain with unconfimed power distribut< ons for extended periods of time, b;i.;dMt/f'/

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the peaking factor surveillances may only be done after the excore detectors h4vg een calibrated to show zero til k. is j

(i.e.,^^;; i..! AM/d

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The intent s' th h ^.e l

1 to have the peaking tor surveillances performed at l

operating power level, which can only be accomplished after the encore detectors are calibrated to show zero tilt and the core returned tol power.

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rough Add are not completed within their a//((s M l

itioninw/taes,theunitmustbe letion ssociated hich the requirements do brought to a MODE or e not apply. To achieve this status THElWEL POWER aust be uced to < 50% RTP within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. Theallowedgompletion i

ime of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> is reasonable, based on operating experience i

regarding the amount of time required to reach the reduced l

power level without challenging plant systems.

y SURVEILLANCE 5R f.2.4.1 f

i REQUIREMENTS y

SR g.2.4.1 1: x di M Y ^ "::: ti, allows QPTR to be calculated with three power range channels if THERMAL POWER is < 75% RTP and one power range channel is isoperable.

This Surveillance verifies that the QPTR, as indicated by theNuclearInstrumentationSystem(NIS)encorechannels,is within its limits. Thefrequencyof7dayswhentheQPTR l

alars is OPERABLE is acceptable because of the low probability that this alars can remain inoperable without detection.

t WhentheQPTRalarsisinoperable,thefrequencyis j

increased to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Thisfrequency is adequate to detect any relatively slow changes in QPTR, because for those i

causes of $)PT)that occur quickly (e.g., a dropped rod),

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SURVEILLANCE SR J 2.4.1 (continued)

REQUIREMENTS there typically are other indications of abnormality that prompt a verification of core power tilt.

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,jf M +r Surveillance [f: ::di'f:d 5 = " ate lid it t:: i;"

.J M is required only when one power range channel is inoperable and the THERMAL POWER is a 754 RTP.

With an NIS power range channel inoperable, tilt monitoring for a portion of the reactor core becomes degraded. Large tilts are likely detected with the remaining channels, but the capability for detection of small power tilts in some Juadrantsisdecreased.requency of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> provides an accura Performing SR 0.0 0.2'It a for ensuring that any tilt remains withi its limits

g. 3. v. < er.

For purposes of monitoring the QPTR when one power range channel is inoperable, the moveable incore detectors are used to confim that the normalized synestric power distribution is consistent with the indicated QPTR and any previous data indicating a tilt.

The incore detector monitoring is perfomed with a full incore flux map or two sets of four thimble locations with quarter core symmetry.,

The two sets of four symmetric thimbles is a set of eight unique detector locations.

These locations are C-8, E-5, E-11. H-3, H-13, L-5, L-11, and M-8,27 C....

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l The symmetric thimble flux map can be used to generate l

symmetric thimble " tilt." This can be compared to a reference symmetric thimble tilt, free the most recent full core flux map, to generate an incore QPTR.

Therefore, QPTR can be used to confim that QPTR is within limits.

With one NIS channel inoperable, the indicated tilt may be changed from the value indicated with all four channels OPERABLE. To confim that no change in tilt has actually occurred, which might cause the QPTR limit to be exceeded, the incore result may be compared against previous flux maps either using the syunstric thimbles as described above or a complete flux map. Nominally, quadrant tilt from the l

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