ML19312B941

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Proposed Tech Specs 3.5.2.4 & 3.5.2.5 Changing Operating Limits & Basic Differences Between Units 1 & 2 Peaking Penalties
ML19312B941
Person / Time
Site: Oconee  Duke Energy icon.png
Issue date: 11/30/1973
From:
DUKE POWER CO.
To:
Shared Package
ML19312B939 List:
References
NUDOCS 7911270729
Download: ML19312B941 (14)
v • d • e


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ATTAC1DfENT 2 PROPOSED REPLACEMENT PAGES FOR "11E I

OCONEE NUCLEAR STATION TECHNICAL SPECIFICATIONS 4

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3.5.2 Control Rod Group _ and Power Distribution Limits

- -s Applicability _

This specification applies to power distribution and operation of control rods during power operation.

Objec_ive To assure an acceptable core power distribution during power operation, to set a limit on potential reactivity insertion from a hypotheti;al control rod ejection, and to assure core suberiticality af ter a reactor trip.

Specification 3.5.2.1 The available shutdown margin shall be not less than 1% Ak/k with the highest worth control rod fully withdrawn.

3.5.2.2 Operation with inoperable rods:

Operation with more than one inoperable rod, as defined in a.

Specificatien 4.7.1 and 4.7.2.3, in the safety or regulating rod groups shall not be permitted.

b.

If a control rod in the regulating or safety rod groups is declared inoperable in the withdrawn position as defined in Specification 4.7.1.1 and 4.7.1.3, an evaluation shall be initiated immediately to verify the existance of 1% Ak/k hot shutdown margin.

Boration may be initiated either to the worth of the inoperable rod or until the regulating and transient rod groups are fully withdrawn, whichever occurs first.

Simultaneously a program of exercising the remain-ing regulating and safety rods shall be initiated to verify operability.

c.

If within one (1) hour of determination of an inoperable rod as defined in Specification 4.7.1, it is not determined that a 1% Ak/k hot shutdown margin exists combining the worth of the inoperable rod with each of the other rods, the reattor shall be brought to the hot standby condition until this margin is established.

d.

Following the determination of an inoperable rod as defined in Specification 4.7.1, all rods shall be exercised within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and exercised weekly until the rod problem is sol-ved.

If a control rod in the regulating or safety rod groups e.

is declared inoperable per 4.7.1.2, power shall be reduced to 60% of the thermal power allowable for the reactor cool-

~%

ant pump combination.

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, 3.5-6

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If a control rod in the regulating or axial power shaping groups

'is declared inoperable per Specification 4.7.1.2, operation may continue provided the rods in the group are positioned such that the rod that was declared inoperable is maintained within allow-able group average position limits of Specification 4.7.1.2 and

.. -.the withdrawal limits of Specification 3.5.2.5.c,

3.5.2.3 The worth of a single inserted control rod shall not exceed 0.5%

Ak/k at rated power or 1.0% Ak/k at hot zero power except for physics testing when the requirements of Specification 3.1.9 shall apply.

3.5.2.4 Quadrant tilt:

a.

If the quadrant power tilt exceeds 4%, except for physics tests, power shall be reduced 2% of the thermal power allowable for the reactor coolant pump combination for each 1% tilt.

b.

Within a period of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, the quadrant power tilt shall be reduced to less than 4%, except for physics tests, or the follow-ing adjustments in setpoints and limits shall be made:

1.

The protection system maximum allowable setpoints (Figure 2.3-2A-Unit 1) shall be reduced 2% in power for each 1% tilt.

2.

The control rod group withdrawal limits (Figures 3.5.2-1A1, 3.5.2-1A2, 3.5.2-2A Unit 1; 3.5.2-1B, 3.5.2-1B2, 3.5.2-2B Unit 2) shall be reduced 2% in power for each 1% tilt in excess of 4%.

3.

The operational imbalance limits (Figure 3.5.2-3A-Unit 1; i

3.5.2-3B-Unit 2) shall be red.uced 2% in power for each 1%

tilt in excess of 4%.

f quadrant tilt is in excess of 25%, except for physics tests or c.

diagnostic testing, the reactor will be placed in the hot shutdown condition.

Diagnostic testing during power operation with a quadrant power tilt is permitted provided the thermal power allowable for the reactor coolant pump combination is restricted i

as stated in 3.5.2.4a above.

d.

Quadrant tilt shall be monitored on a minimum frequency of once every two hours during power operation above 15% of rated power.

3.5.2.5 Control rod positions:

a.

Technical Specification 3.1.3.3 (safety rod withdrawal) does not prohibit the exercising of individual safety rods as required by Table 4.1-2 or apply to inoperable safety rod limits in Technical Specification 3.5.2.2.

b.

Operating rod group overlap shall be 25% 15% between two sequential groups, cxcept for physics tests.

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Except for physics tests or exercising control rods, the control c.

rod withdrawal limits are specified on Figures 3.5.2-1A1, 3.5.2-1B1, 3.5.2-1A2, and 3.5.2-1B2 for four pump operation and on Figure 3.5.2-2A and 3.5.2-2B for three or two pump operation.

If the control rod position limits are exceeded, corrective measures shall be taken inmediately to achieve an acceptable control rod position. Acceptable control rod positions shall be attained within four hours.

d.

Except for physics tests, power shall not be increased into the control rod withdrawal window unless the xenon reactivity is within 90% of the equilibrium value at rated power and asymptotically Reactor Power Imbalance shall be monitored on a frequency not to e.

exceed two hours during power operation above 40 percent rated power.

Except for physics tests, imbalance shall be maintained within the envelope defined by Figure 3.5.2-3A and 3.5.2-3B.

If the imbalance is not within the envelope defined by Figure 3.5.2-3A and 3.5.2-3B, corrective measures shall be taken to achieve an l

acceptable imbalance.

If an acceptable imbalance is not achieved i

within four hours, reactor power shall be reduced until imbalance limits are met.

l The control rod drive patch panels shall be locked at all times with 3.5.2.6 limited access to be authorized by the superintendent.

Bases i

The power-imbalance envelope defined in Figure 3.5.2-3A and 3.5.2-3B is based on LOCA analyses which have defined the maximum linear heat rate (see Figure 3.5.2-4) such that the maximum clad temperature will not exceed the interim Acceptance Criteria.

l Corrective measures will be taken immediately should the indicated quadrant tilt, rod position, or imbalance be outside their specified boundary.

Operation in a situation that would cause the interim acceptance critAria to be approached should a LOCA o: cur is highl' distribution parameters (quadrant tilt,. improbable because all of the power rod position, and imbalance) must be at their limits while simultaneously all other engineering and uncertainty

. factors are also at their limits.*

Conservatism is introduced by application of:

Nue' lear uncertainty factors a.

b.

Thermal calibration Fueldensificationelfects c.

d.

Hot rod manufacturing tolerance factors The 30 percent overlap between successive control rod groups is allowed since the worth of a rod is lower at the upper and lower part of the stroke.

Control rods are arranged in groups or banks defined as follows:

  • Actual operating limits depend on whether or not incore or excore detectors are used and their respective instrument and calibration errors.

The method used to define the operating limits is defined in plant operating procedures.

3.5.

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s Group Function 1

Safety 2

Safety 3

Safety 4

Safety 5

Regulating 6

Regulating 7

Xenon transient override 8

APSR (axial power shaping bank)

The minimum available rod worth provides for achieving hot shutdown by reactor trip at any time assuming the highest worth control rod renains in the full out position.(1)

Inserted rod groups during power operation will not contain single rod worths greater than 0.5% ak/k.

This value has been shown to be safe by the safety analysis of the hypothetical rod ejection accident.(2) A single inserted control rod worth of 1.0% ak/k at beginning of life, hot, zero power would result in the same transient peak thermal power and therefore the same environmental consequences as a 0.5% ak/k ejected rod worth at rated power.

Control rod groups are withdrawn in sequence beginning with Group 1.

Groups 5, 6, and 7 are overlapped 25 percent.

The normal position at power is for Groups 6 and 7 to be partially inserted.

The quadrant power tilt limits set forth in Specification 3.5.2.4 have been j

established within the thermal analysis design base using the definition of quadrant power tilt given in Technical Specifications, Section 1.6.

These limits in conjunction with the control rod position limits in Specification 3.5.2.5c ensure that design peak heat rate criteria are not exceeded during normal operation when including the effects of potential fuel densification.

The quadrant tilt and axial imbalance monitoring in Specifications 3'.5.2.4d and 3.5.2.Se respectively normally will be performed in the process computer.

The two-hour frequency for monitoring these quantities will provide adequate surveillance when the computer is out of service.

The control rod withdrawal window is defined as the permissible operating region above 92 percent 4 power for Unit 1 and 80 percent power for Unit 2 as shown in fae control rod group withdrawal limits for four pump operation.

REFEREMCES 1Section 3.2.2.1.2 Section 14.2.2.2 l

i 3.5-8a e

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ROD INDEX I S THE PET:CENTAGE 5RJM OF THE UITHDRACAL OF THE OPERATI NG GROUPS.

2. THE ADDI Tl ON AL RESTRICTlONS ON WI THDRAWAL (HASHED AREAS) ARF. MODI FI ED AFTER 285 FULL POWER DAYS OF OPERAT!ON.

Withdrawal Limit 125 188 235

-284 92 RESTRICTED 172 250 U

REGION E 80 m.

as 60 g

PERMISSIBLE a

OPERATING f

D REG 10N

$ 40

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1 50 100 150 200 250 300 Rod Index, *, Withdrawal 0

25 50 75 100 t

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Group 7 0

25 50 75 100 I

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CONTROL ROD GROUP WITH0RAWAL LIMITS FOR,4 PUMP OPERATION UNIT 1

.upajj CCONEE NUCLEAR STATION 3.5 8b Figure 3.5.2-1A1

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ROD INDEX 15 THE PERCENTAGE Slt) 0F THE WIniDRAWAL OF.

THE OPERATING GROUPS.

2.

THE ADDITIONAL RESTRICTIONS ON WITHDRAWAL (HASHED

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AREAS) ARE IN EFFECT AFTER 285 FULL POWER DAYS OF OPERATION.

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Group 5 CONTROL R00 GROUP WITHDRAWAL LIMITS FOR,4 PUMP OPERATION UNIT 1 MN 2

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ut natij OCONEE NUCLEAR STATION NLGs 3.5-8c Figure 3.5.2-1A2 l

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ROD INDEX I S THE PERCENTAGE SUM OF THE WITHDRAWAL OF THE OP ERATI NG GROUP S.

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2. THE ADDITIONAL RESTRICTIONS ON WITHDRAWAL (HASHED AREAS) ARE MODI FI ED AFTER 435 FULL POWER DAYS OF OPERATION.

a Withdrawal Limit 291'7 125 195 235 100 90 RESTRICTED

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ROD I NDEX i S TH E P ERCENTAGE SU'.1 0 F THE WI THDRAWAL OF THE OPERATI NG GROUP S.

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2. THE ADDI TION AL RESTRI CTIONS ON WI THDRAWAL (HASHED AREAS) ARE IN EFFECT AFTER 43S FULL POWER D AYS OF OPERATION.

291.7 125 270 100 o

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Group 5 CONTROL R00 GROUP WITH0RAWAL LIMITS FOR 4 PUMP OPERATION s

[@ontram UNIT 2 OCONEE NUCLEAR STATION

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1. ROD INDEX 1 S THE PERCENTAGE SLN OF mE Ul EDRACAL OF THE OPERATING GROUPS.

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ROD INDEX 1 S THE PERCENTAGE SUM OF THE 01 THDRAWAL 0

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{cht mse) OCONEE NJCLEAR STATION ng, 3.5-8g Figure 3.5.2 - 23

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