ML20138E231

Amends 3 & 1 to Licenses DPR-80 & DPR-82,respectively, Revising Tech Specs Re Axial Flux Difference Limits

ML20138E231
Person / Time
Site:	Diablo Canyon
Issue date:	11/29/1985
From:	Varga S Office of Nuclear Reactor Regulation
To:
Shared Package
ML20138E238	List: ML20138E231 ML20138E240
References
TAC-59659, NUDOCS 8512130375
Download: ML20138E231 (17)

Text

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'q UNITED STATES 8

s NUCLEAR REGULATORY COMMISSION c.

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WASHINGTON, D. C. 20555 o

s PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON NUCLEAR POWER PLANT, UNIT 1 DOCKET NO. 50-275 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 3 License No. DPR-80 1.

The Nuclear Regulatory Commission (the Commission) has found that:

A.

The application for amendment dated September 6,1985 (LAR 85-09) by Pacific Gas & Electric Company (the licensee) complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's rules and regulations set forth in 10 CFR Chapter 1; B.

The facility will operate in conformity with the application, as amended, the provisions of the Act, and the rules and regulations of the Comission; C.

There is reasonable assurance (1) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations; D.

The issuance of this amendment will not be inimical to the common defense and security or to-the health and safety of the public; and E.

The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.

2.

Accordingly, the license is amended by a change to the combined Technical Specifications for Units 1 and 2 as indicated in the attachment to this license amendment, and paragraph 2.C.(2) of Facility Operating License No. DPR-80 is hereby amended to read as follows:

P

(2) Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 3, and the Environmental Protection Plan contained in Appendix B are hereby incorporated in the license.

PG&E shall operate the facility in accordance with the Technical 4

Specifications and the Environmental Protection Plan.

3.

This license amendment becomes effective when Unit I reaches a burnup of 8000 MWD /MTU.

FOR THE NUCLEAR REGULATORY COWilSSION I

Varga, ctor PWR Project Directo a e No. 3 Division of PWR Lice ing-A

Attachment:

Changes to the Technical Specifications Date of Issuance: NOV ",9 iM5

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NOV 2 91985

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A ATTACHMENT TO LICENSE AMENDMENT NOS. 3 AND 1 FACILITY OPERATING LICENSE NOS. DPR-80 AND DPR-82 DOCKET NOS. 50-275 AND 50-323, RESPECTIVELY J

Replace the following pages of the Appendix A Technical Specifications with the enclosed pages. The revised pages are identified by Amendment Number and contain vertical lines indicatina the area of chanoe.

Amendment Paoes 3/4 2-1 3/4 2-la 3/4 2-lb 3/4 2-2 3/4 2-3 3/4 2-4 8 3/4 2-1 B 3/4 2-2 B 3/4 2-4 B 3/4 2-5 B 3/4 2-6 7

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NUCLEAR REGULATORY COMMISSION UNITED STATES j

.g WASHINGTON, D. C. 20555 e

PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON NUCLEAR POWER PLANT, UNIT 2 DOCKET NO. 50-323 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 1 License No. DPR-82 1.

The Nuclear Regulatory Comission (the Commission) has found that:

A.

The application for amendment dated September 6,1985 (LAR 85-09) by Pacific Gas & Electric Company (the licensee) complies with the standards and requirements of the Atomic Energy Act of 1954, as -

amended (the Act), and the Commission's rules and regulations set forth in 10 CFR Chapter 1; B.

The facility will operate in confonnity with the application, as amended, the provisions of the Act, and the rules and regulations of the Commission; C.

There is reasonable assurance (i) that the activities authorized i

by this. amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be t

conducted in compliance with the Commission's regulations; D.

The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.

The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.

2.

Accordingly, the license is amended by a change to the combined Technical Specifications for Units 1 and 2 as indicated in the attachment to this l'icense amendment, and paragraph 2.C.(2) of Facility Operating License No. DPR-82 is hereby amended to read as follows:

e

. (2) Technical S]ecifications (SSER 32, Section 8)* and Environmental Protection )lan The Technical Specifications contained in Appendix A, as revised through Amendment No.1, and the Environmental Protection Plan contained in Appendix B are hereby incorporated in this license.

PG&E shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

3.

This license amendment becomes effective when Unit I reaches a burnup of 8000 MWD /MTV.

FOR THE NUCLEAR REGULATORY COMMISSION e

r r

PWR Project Dire 't ate No. 3 Division of PWR L'ce sing-A

Attachment:

Changes to the Technical Specifications Date of Issuance: MOV 2 01985

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NOV 2 91985

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ATTACHMENT TO LICENSE AMENDMENT NOS. 3 AND 1 FACILITY OPERATING LICENSE NGS. DPR-80 AND DPR-82 DOCKET NOS. 50-275 AND 50-323, RESPECTIVELY Replace the following pages of the Appendix A Technical Specifications with the enclosed pages.- The revised pages are identified by Amendment Number and contain vertical lines indicating the area of change.

Amendment Pages 3/4 2-1 3/4 2-la 3/4 2-lb 3/4 2-2 3/4 2-3 3/4 2-4 8 3/4 2-1 B 3/4 2-2 B 3/4-2-4 B 3/4 2-5 B 3/4 2-6 f

1 i

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3/4.2 POWER DISTRIBUTION LIMITS 3/4.2.1 AXIAL FLUX DIFFERENCE i

LIMITING CONDITIONS FOR OPERATION 3.2.1.1 For Unit 1 the indicated AXIAL FLUX DIFFERENCE (AFD) shall be main-i tained within the allowed operational space defined by Unit 1 Figure 3.2-la.

APPLICABILITY:

For Unit 1 MODE 1 AB0VE 50 PERCENT RATED THERMAL POWER *.

ACTION:

a.

With the indicated AXIAL FLUX DIFFERENCE outside of the Unit 1 Figure 3.2-la limits, 1.

Either restore the indicated AFD to within the Unit 1 Fig-ure 3.2-la limits within 15 minutes, or i

2.

Reduce THERMAL POWER to less than 50% of RATED THERMAL POWER within 30 minutes and reduce the Power Range Neutron Flux - High Trip setpoints to less than or equal to 55 percent of RATED' THERMAL POWER within the next 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

b.

THERNAL POWER shall not be increased above 50% of RATED THERMAL POWER unless the indicated AFD is within the Unit 1 Figure 3.2-la limits.

SURVEILLANCE REQUIREMENTS 4.2.1.1.1 For Unit 1 the indicated AXIAL FLUX DIFFERENCE shall be determined to be within its limits during POWER OPERATION above 50 percent of RATED THERMAL POWER by:

a.

Monitoring the indicated AFD for each OPERABLE excore channel:

1.

At least once per 7 days when the AFD Monitor Alarm is OPERABLE, and 2.

At least once per hour for the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after restoring the AFD Monitor Alarm to OPERABLE status.

b.

Monitoring and logging the indicated AXIAL FLUX DIFFERENCE for each OPERABLE excore channel at least once per hour for the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and at least once per 30 minutes thereafter,.when the AXIAL FLUX i

DIFFERENCE Monitor Alarm is inoperable. The logged values of the indicated AXIAL FLUX DIFFERNECE shall be assumed to exist during the interval preceding each logging.

1 4.2.1.1.2 For Unit 1 the indicated AFD shall be considered outside of its limits when at least 2 OPERABLE excore channels are indicating the AFD to be outside the limits.

4

• See Special Test Exceptions Specification 3.10.2 DIABLO CANYON - UNITS 1 & 2 3/4 2-1 AMENDMENTS NOS. 3 & 1

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3/4.2 POWER DISTRIBUTION LIMITS 3/4.2.1 AXIAL FLUX DIFFERENCE LIMITING CONDITION FOR OPERATION 3.2.1.1 For Unit 2 the indicated AXIAL FLUX DIFFERENCE (AFD) shall be main-l tained within a 15% target band (flux difference units) about the target flux difference when THERMAL POWER is above 50% of RATED THERMAL POWER. The indi-cated AFD may deviate outside the above required target based at greater than or equal to 50% but less than 90% of RATED THERMAL POWER provided the indicated AFD is within the Acceptable Operation Limits of Unit 2 Figure 3.2-lb and the l

cumulative penalty deviation time does not exceed I hour during the previous 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

The indicated AFD may deviate outside the above required target band at greater than 15% but less than 50% of RATED THERMAL POWER provided the cumulative penalty deviation time does not exceed 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> during the previous 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

APPLICABILITY:

For Unit 2 MODE 1 above 15% of RATED THERMAL POWER *.

l ACTION:

a.

With the indicated AFD outside of the 15% target band and with THERMAL POWER greater than or equal to 90% of RATED THERMAL POWER, within 15 minutes, either:

1.

Restore the indicated AFD to within the target band limits, or 2.

Reduce THERMAL POWER to less than 90% of RATED THERMAL POWER.

i b.

With the indicated AFD outside of the above required target band for more than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of cumulative penalty deviation time during the previous 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or outside the Acceptable Operation Limits of Unit 2 Figure 3.2-1b and with THERMAL POWER less than 90% but equal l

to or greater than 50% of RATED THERMAL POWER, reduce:

1.

THERMAL POWER to less than 50% of RATED THERMAL POWER within j

30 minutes, and 2.

The Power Range Neutron Flux - High# Setpoints to less than or equal to 55% of RATED THERMAL POWER within the next 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

• See Special Test Exceptions Specification 3.10.2

1. Surveillance testing of the Power Range Neutron Flux channel may be performed pursuant to Specification 4.3.1.1 provided the indicated AFD is maintained within the Acceptable Operation Limits of Unit 2 Figure 3.2-lb.

A total of l

16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> operation may be accumulated with the AFD outside of the above required target band during testing without penalty deviation.

DIABLO CANYON - UNITS 1 & 2 3/4 2-lb AMENDMENTS NOS. 3 & 1

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4 POWER DISTRIBUTION LIMITS LIMITING CONDITION FOR OPERATION ACTION (Continued) c.

With the indicated AFD outside of the abo"e required target band for more than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of cumulative penalty deviation time during the pre-vious 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and with THERMAL POWER less than 50% but greater than 15% of RATED THERMAL POWER, the THERMAL POWER shall not be increased equal to or greater than 50% of RATED THERMAL POWER until the indicated AFD is within the above required target band.

I SURVEILLANCE REQUIREMENTS 5 -

4.2.1.2.1 For Unit 2 the indicated AFD shall be determined to be within its l

limits during POWER OPERATION above 15% of RATED THERMAL POWER by:

a.

Monitoring the indicated AFD for each OPERABLE excore channel:

1)

At least once per 7 days when the AFD Monitor Alarm is OPERABLE, and 2)

At least once per hour for the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after restoring the AFD Monitor Alarm to OPERABLE status.

b.

Monitoring and logging the indicated AFD for each OPERABLE excore channel at least once per hour for the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and at least i

once per 30 minutes thereafter, when the AFD Monitor Alarm is in-h

.. operable.

The logged values of the indicated AFD shall be assumed to

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exist during the interval precedirig each logging.

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4.2.1.2.2 For Unit 2 the indicated AFD shall be considered outside of its + 5%

l' target band when two or more OPERABLE excore channels are indicating the AFD to be outside the target band.

Penalty deviation outside of the + 5% target band e

j shall be accumulated on a time basis of:

a.-

One minute penalty deviation for each 1 minute of POWER OPERATION outside of the target band at THERMAL POWER levels equal to or above

-50% of RATED THERMAL POWER, and b.

One-half minute penalty deviation for each 1 minute of POWER OPERATION outside of the target band at THERMAL POWER levels between 15% and 50% of RATED THERMAL POWER.

l l-DIABLO CANYON - UNITS 1 & 2 3/4 2-2 AMENDMENTS NOS.'3 & 1

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POWER DISTRIBUTION LIMITS SURVEILLANCE REQUIREMENTS (Continued) 4.2.1.2.3 For Unit 2 the target flux difference of each OPERABLE excore channel l

shall be determined by measurement at least once per 92 Effective Full Power Days. The provisions of Specification 4.0.4 are not applicable.

4.2.1.2.4 For Unit 2 the target flux difference shall be updated at least once l.

per 31 Effective Full Power Days by either determining the target flux dif-ference pursuant to Specification 4.2.1.3 above or by linear interpolation between the most recently measured value and 0% at the end of the cycle life.

The provisions of Specification 4.0.4 are.not applicable.

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DIABLO CANYON - UNITS 1 & 2 3/4 2-3 AMENDMENTS NOS. 3 & 1

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l FLUX DIFFERENCE (All %

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FIGURE 3.2-lb UNIT 2 AXIAL FLUX DIFFERENCE LIMITS AS A FUNCTION OF RATED THERMAL POWER

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I 3/4.2 POWER DISTR.fBUTION LIMITS J

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i The specifications of this section provide assurance of fuel integrity g

during Condition I (Normal Operation) and II (Incidents of Moderate Frequency) 4 events by:

(a) maintaining the ainimum DNBR in the core greater than or equal to 1.30 during normal operation and in short term transients, and (b) limiting

• '4 the fission gas release, fuel pellet temperature and cladding mechanical e TM.

properties to within assumed design criteria.

In addition, limiting the peak

,,'s linear power density during Condition I events provides assurance that the initial conditions assumed for the LOCA analyses are met and the ECCS acceptance

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criteria limit of 2200'F is not exceeded.

The definitions of certain hot channel and peaking factors as used in these specifications are as follows:

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F (Z)

Heat Flux Hot Channel Factor, is defined as the maximum local heat q

flux on the surface of a fuel rod at core elevation Z divided by the

' average fuel rod heat flux, allowing for manufacturing tolerances on fuel pellets and rods; x

F Nuclear Enthalpy Rise Hot Channel Factor, is defined as the ratio of g

the integral of linear power along the rod with the highest integrated 2

power to the average rod power; and l

\\c.w F (Z)

Radia1 Peaking Factor, is defined as the ratio of peak power density s

to a' erage power density in the horizontal plane at core elevation Z.

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y' 3/3.2.1 K AXIAL FLUX DIFFERENCE i:

i UNIT 1:

The limits on AXIAL FLUX DIFFERENCE assure that the f (Z) upper bound enve-q limit f

lope of F times the normalized axial peaking factor is not exceeded during q

either normal operation or in the event of xenon redistribution following power changes.

Provisions for monitoring the AFD on an automatic basis are derived from the plant process computer through the AFD Monitor Alarm. The computer determines the one minute average of each of the OPERABLE excore detector outputs and provides an alarm message immediately if the AFD for at least 2 of 4 or 2 of 3 OPERABLE excore channels are outside the AFD limits and the THERMAL POWER is greater than 50 percent of RATED THERMAL POWER.

j UNIT 2:

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Ttte limits on AX1AL FLUX DIFFERENCE (AFD) assure that the F (Z) upper bound 9

s envelope of 2.32 times the normalized axial peaking factor is not exceeded during either normal. operation or in the event of xenon redistribution following i

power changes.

DIABLO CANYON - L' NITS 1 & 2 8 3/4 2-1 AMENDMENTS NOS. 3 & 1

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u POWER DISTRIBUTION LIMITS BASES

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AXIAL FLUX DIFFERENCE (Continued) 1 Target flux difference is determined at equilibrium xenon conditions.

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full-length rods may be positioned within the core in accordance with their re-

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spective insertion limits and should be inserted near their normal position for steady state operation at high power levels.

The value of the target flux dif-ference obtained under these conditions divided by the fraction of RATED THERMAL POWER is the target flux difference at RATED THERMAL POWER for the associated core burnup conditions. Target flux differences for other THERMAL POWER levels are obtained by multiplying the RATED THERMAL POWER value by the appropriate fractional THERMAL POWER level. The periodic updating of the target flux dif-ference value is necessary to reflect core burnup considerations.

-Although it is intended that the plant will be operated with the AFD within the +5% target band about the target flux-difference, during rapid

' plant THERMXL POWER changes, control rod motion will cause the AFD to deviate outside of the target band..This deviation will not affect the xenon redistri-bution sufficiently to change the envelope of peaking factors which may be reached subsequently (with the AFD within the target band) provided the-time duration of the deviation is limited.

Accordingly, a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> penalty deviation limit cumulative during the previous 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is provided for operation outside of the target band but within the limits of Unit 2 Figure 3.2-lb while at l

THERMAL POWER levels between 50% and 90% of. RATED THERMAL POWER.

For THERMAL i

POWER levels between 15% and 50% of rated THERMAL POWER, deviations of the AFD outside of the target band are less significant.

The penalty of.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> actual time reflects this reduced significance.

Provisions for monitoring the AFD on an automatic basis are derived from j

the plant process computer through the AFD Monitor Alarm. The computer determines the one minute average of each of the OPERABLE excore detector outputs and provides an' alarm message immediately if the AFD for 2 or more OPERABLE excore channels are outside the target band and the THERMAL POWER is greater than 90%

of RATED THERMAL POWER. During operation at THERMAL POWER 1evels between 50%

and 90% and between 15% and 50% RATED THERMAL POWER, the computer outputs an alarm message when the penalty deviation accumulates beyond the limits of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, respectively.

-Figure B 3/4 2-1 shows'a typical monthly target band.

3/4.2.2 and 3/4.2.3 HEAT FLUX HOT CHANNEL FACTOR, and RCS FLOWRATE AND NUCLEAR ENTHALPY RISE HOT CHANNEL FACTOR The limits on Heat Flux Hot Channel Factor, RCS Flowrate, and Nuclear Enthalpy Rise Hot Channel Factor ensure that:

(1) the design limits on peak local power density and minimum DNBR are not exceeded, and (2) in the event'of a LOCA the peak. fuel clad temperature will not exceed the 2200'F ECCS acceptance criteria limit.

5 DIABLO CANYON -. UNITS 1 & 2 B 3/4 2-2 AMENDMENTS NOS 3 & 1

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. POWER DISTRIBUTION LIMITS BASES HEATFLUX'HOTCNANNELFACTOR,andRCSFLOWRATEANDNUCLEARENTHALPYRISEHOT CHANNEL FACTOR (Continued) r Each of these is measurable but will normally only be determined periodically as specified in Specifications 4.2.2 and 4.2.3.

This periodic surveillance is sufficient to ensure that the limits are maintained provided:

1.

Control rods in a single group move together'with no individual rod insertion differing by more than + 12 steps', indicated, from the j

group demand position, j

Control rod groups are s'quenced with overlapping groups as described 2.

e in Specification 3.1.3.6,~

3.

The control rod insertion limits of Specifications 3.1.3.5 and 3.1.3.6 are maintained, and 4.

The axial power distribution, expressed in terms of AXIAL FLUX DIFFERENCE, is maintained within the limits.

jFhwillbemaintainedwithin'itslimitsprovidedConditions1.through 4., above, are maintained. As noted on Figure 3.2-3a and Figure 3.2-3b, RCS

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flow rate and Fh may be " traded off" against one another (i.e., a low measured RCS flow rate is acceptable if the measured F is also low) to ensure that the H

calculated DNBR will.not be below the design DNBR value. TherelaxationofFh I as a function of THERMAL POWER allows changes in the radial power shape for all permissible rod insertion limits.

R, as calculated per Specification.3.2.3 and used in Figure 3.2-3a and Figure 3.2-3baccountsforFhlessthanor'equalto1.49.

i This value is the ll valueusedin'thevariousaccidentana7yseswhereFhinfluencesparameters 7

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-other than DNBR, e.g., peak clad temperature, and thus is the maximum "as Thus,knowingthe"asmeasured"valuesofFhand I

~ measured" value allowed.

? RCS flow allows for " trade offs" in excess of R equal to 1 for'the purpose of offsetting the rou' bow DNBR penalty.

Fuel rod bowing reduces thesvalue of DNB ratio.

Credit is available to offset this reduction in the generic margin.

The generic margin totaling 9.1% DNBR.is derived from the difference between the design and required values

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on the following items:

(a) design'DNBR limit, (b) grid spacing multiplier, (c) thermal diffusion coefficient, -(d) DNBR spacer factor multiplier and

'(e) pitch reduction. The rod bow penalty is calculated with the method described in WCAP-8691, Revision 1, and is completely compensated by the-available margin of 9.1%.

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DIABLO CANYON - UNITS 1 & 21 8 3/4 2-4 AMENDMENTS NOS. 3 & 1

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, POWER DISTRIBUTION LIMITS BASES HEAT FLUX HOT CHANNEL FACTOR, and RCS FLOWRATE and NUCLEAR ENTHALPY RISE HOT CHANNEL FACTOR (Continued)

When an F measurement is taken, an allowance for both experimental error q

and manufacturing tolerance must be made.

An allowance of 5% is appropriate for a full core map taken with the incore detector flux mapping system and a 3% allowance is appropriate for manufacturing tolerance.

WhenRCSflowrateandFfg are measured, no additional allowances are necessary prior to comparison with the limits of Figures 3.2-3.

Measurement N

errors of 3.5% for RCS total flow rate and 4% for F have been allowed for in determination of the design DNBR value.

The 12-hour periodic surveillance of indicated RCS flow is sufficient to detect only flow degradation which could lead to operation outside the acceptable region of operation shown on Figure 3.2-3a and Figure 3.2-3b.

The Radial Peaking Factor, Fxy(Z), is measured periodically to provide addi-tional assurance that the Hot Channel Factor, F (Z), remains within its limit.

q The F limit for RATED THERMAL POWER (FRTP) as provided in the Radial Peaking xy x

Factor Limit Report per Specification 6.9.1.8 was determined from expected power control maneuvers over the full range of burnup conditions in the core.

3/4.2.4 QUADRANT POWER TILT RATIO The QUADRANT POWER TILT RATIO limit assures that the radial power distri-bution satisfies the design values used in the power capability analysis.

Radial power distribution measurements are made during startup testing and 1

periodically during power operation.

l The limit of 1.02 at which corrective action is required provides DNB and linear heat generation rate protection with x y plane power tilts.

The limit of 1.02 was selected to provide an allowance for the uncertainty associated i

with the indicated power tilt.

l The 2-hour time allowance for operation with a tilt condition greater than 1.02 but less than 1.09 is provided to allow identification and correction l

of a dropped or misaligned rod.

In the event such action does not correct the tilt, the margin for uncertainty on F is reinstated by reducing the power by q

3% for each percent of tilt in excess of 1.

DIABLO CANYON - UNITS 1 & 2 B 3/4 2-5 AMENDMENTS NOS. 3 & 1

POWER DISTRIBUTION LIMITS BASES i

3/4.2.5 DNB PARAMETERS The limits on the DNB-related parameters assure that each of the parameters are maintained within the normal steady-state envelope of operation assumed in the transient and safety analyses.

The limits are consistent with the initial FSAR assumptions and have been analytically demonstrated adequate to maintain a minimum DNBR of 1.30 throughout each analyzed transient.

The 12-hour periodic surveillance of these parameters through instrument readout is sufficient to ensure that the parameters are restored within their limits following load changes and other expected transient operation.

')

i DIABLO CANYON - UNITS 1 & 2 8 3/4 2-6 AMENDMENTS NOS. 3 & 1 w

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