ML19326B829

Proposed Tech Specs 3.5.2 Re Control Rod Insertion Limits. Diagrams Encl

ML19326B829
Person / Time
Site:	Arkansas Nuclear
Issue date:	08/02/1974
From:	ARKANSAS POWER & LIGHT CO.
To:
Shared Package
ML19326B826	List: ML19326B825 ML19326B829
References
NUDOCS 8004180574
Download: ML19326B829 (6)

Text

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. . . O If a control rod in the regulating or axial power shaping groups 6.

is declared inoperable per Specification 4.*/.1.2, operation above 60 percent of the thermal power allowable for the reactor coolant pump combination may continue provided the rods in the group are positioned such that the rod that was declared ineperable is main-tained within allowable group average position limits of Specifica-tion 4.7.1.2 and the withdrawal limits of Specification 3.5.2.5.3.

3.5.2.3 The worth of a single inserted control rod shall not exceed 0.65%Ak/k at rated power or 1.0%Ak/k at hot zero power except for physics testing when the requirements of Specification

• 3.1.8 shall apply.

3.5.2.4 Quadrant' tilt:

1. Except for physics tests, if quadrant tilt exceeds 4%, power shall be reduced immediately to below the power level cutoff (see Figures 3.5.2-1A, 3.5.2-1B and 3.5.2-1C). Morever, the power level cutoff l

value shall be reduced 2% for each 1% tilt in excess of 4% tilt.

For less than 4 pump operation, thermal power shall be reduced 2%

of the thermal power allowable for the reactor coolant pump combina-tion for each 1% tilt in excess of 4%.

2. 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 following adjust-ments in setpoints and limits shall be made:

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

b. The control rod group withdrawal limits (Figures 3.5.2-1A, 3.5.2-1B and 3.5.2-1C) shall be reduced 2% in power for each l 1% tilt in excess of 4%.

c. The operational imbalance limits (Figure 3.5.2-3) shall be reduced 2% in power for each 1% tilt in excess of 4%.

3. If quadrant tilt is in excess of 25%, except for physics tests or diagnostic testing, the reactor will be placed in the hot shutdown condition. Diagnostic testing during power operation with a quad-rant power tilt is permitted provided the thermal power allowable

, for the reactor coolant pump combination is restricted as stated in 3.5.2.4.1 above. l

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

3.5.2.5 Control rod positions:-

1. Technical Specification 3.1.3.5 (safety rod withdrawal) does not prohibit the exercising of individual safety rods as required by

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Table 4.1-2 or apply to inoperable safety rod limits in Technical ,

Specification 3.5.2.2.

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2. Operating rod group overlap shall be 25% + 5 between two sequential groups, except for physics tests.

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3. Except for physics ' tests or exercising control rods, the control rod withdrawal limits are specified on Figures 3.5.2-1A, 3.5.2-1B

j. and 3.5.2-1C for four pump operation and on Figure 3.5.2-2 for three or two pump operation. If the control rod position limits are exceeded, corrective measures shall be taken immediately to achieve an acceptable control rod position.- Acceptabic control rod posi-

, tions shall be attained within four hours.

4. Except for physics tests, power shall not be increased above the power level cutoff (see Figures 3.5.2-1) unless the xenon reactivity is within 10 percent of the equilibrium value for opration at rated power and asymptotically approaching stability.

3.5.2.6 Reactor Power Imbalance shall be monitored on a frequency not to exceed two hours during power operation above 40 percent rated power. .Except i for physics tests, imbalance shall be maintained within the envelop defined by Figure 3.5.2-3. If the impalance is not within the envelop

defined by Figure 3.5.2-3, corrective measures shall be taken to achieve j an acceptable imbalance. If an acceptable imbalance is not achieved

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

e 3.5.2.7 The control rod drive patch panels shall be locked at all times with limited access to be authorized by the Superintendent.

Bases

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The power-imbalance envelop defined in Figure 3.5.2-3 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 Final Acceptance Criteria.

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 Final Acceptance Criteria to be approached should a LOCA occur is highly improbable because all of the power distribution [

parameters (quadrant tilt, rod position, and imbalance) must be at their limits j while simultaneously all other engineering and uncertainty factors are also at their limits.* Conservatism is introduced by application of:

a. Nuclear uncertainty factors 4 -b. Therma 1 ' calibration l c.- Fuel- densification effects

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.

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ROD INDEX IS THE PERCENTAGE SUM OF THE WITHDRAWAL OF THE OPERATING GROUPS.

2 THE ADDI TION AL RESTRI CTIONS ON WI THDR AWAL (HASHED AREAS) ARE MODIFIED AFTER 100 FULL POWER DAYS OF OPERATION. (SEE FIGURE 3.5.2.1B) 100 ~

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I t t I t 50 100 150 200 250 300 Rod index, ",Wittidrawal 0 2,5 5,0 75 ,100 Group 7 0

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Group 6 0 25 50 75 100 t i I e i T:roup 5 ARKANSAS POWER & LIGHT CO. CONTROL R00 GROUP WITH0RAWAL FIG. NO. I d

ARKANSAS NUCLEAR ONE-UNIT I LIMITS FOR 4 PUMP OPERATION 3.5.2-1A J L.

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i i i i i 1 ROD INDEX 15 THE PERCENTAGE SUM OF THE WI THDRAWAL OF THE OPERATING GROUPS.

2. THC ADDITIONAL RESTRICTIONS ON WITHDRAWAL (HASHED AREAS) ARE IN EFFECT AFTER 100 FULL POWER DAYS OF OPERATION. RESTRICTIONS ON WITHDRAWAL (HASHED AREAS) ARE FURTHER MODI FI ED AFTER 435 FULL POWER DAYS OF OPERATION. ( SEE F I GURE 3. 5. 2- 1 C. )

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ARKANSAS NUCLEAR ONE UNIT I LIMITS FOR 4 PUMP OPERATION 3.5.2-1B 48c

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j i i i i i 1 ROD INDEX i S THE P ERCENTAGF Suv ';r Tut W THDRAWAL OF THE OPERATING GROUPS.

2. THE ADDI TION AL RESTRI CTIONS ON WI THDRAWAL (HASHED AREAS) ARE IN EFFECT AFTER 435 FULL POWER DAYS OF OPERATION.

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Group i 0 25 50 75 100 a e a a I Group 5 ARKANSAS POWER & LIGHT CO. CONTROL R00 GROUP WITH0RAWAL FIG.NO.

ARKANSAS NUCLEAR ONE-UNIT 1 LIMITS FOR 4 PUMP OPERAliON 3. 5. 2- 1 C 4 8 cc.

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10 0 2 4 6 8 10 12 i Elevation from Bottom of Core, ft LOCA LIMITED MAXIMUM ALLOWABLE l

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ARKANSAS POWER & LIGHT CO. LOCA LIMITED MAXIMUM ALLOWABLE FIG.NO.

ARKANSAS NUCLE AR ONE-UNIT I LINEAR HEAT RATE 3.5.2-4 484 L