ML19326C660

Proposed Tech Specs 3.1.3 Supplementing 750709 Submittal Re ECCS re-evaluation.Diagrams Re Control Rod Group Withdrawal Limits for Pump Operation Encl

ML19326C660
Person / Time
Site:	Arkansas Nuclear
Issue date:	08/15/1975
From:	ARKANSAS POWER & LIGHT CO.
To:
Shared Package
ML19326C655	List: ML19326C654 ML19326C660
References
NUDOCS 8004250478
Download: ML19326C660 (10)

Text

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3.1.3

!!inimun Conditions For Criticality Specification 3.1.3.1 The. reactor coolant temperature shall be above 525 F except for portions of low power physics testing when the requirements 3f Specification 3.1.8 shall apply.

3.1.3.2 Reactor coolant temperature shall be above DTT + 10 F.

3.1.3.3 lihen the reactor coolant temperature is below the cininua tempera-ture specified in 3.1.3.1 above, except for portions of low power physics testing when the requirements of Specification 3.1.8 shall apply, the reactor shall be suberitical by an amount equal to or greater than the calculated reactivity insertion due to depressurization.

l 3.1.3.4 The reactor shall be maintained suberitical by at least 1 percent Ak/k until. a steam bubble is forned and an indicated unter level between 45 and 305 inches is established in the pressurizer.

3.1.3.5 Except for physics tests and as limited by 3.5.2.1, safety rod groups shall be fully uithdrawn and the regulating rods shall be positioned within their position linits as defined by Specifi-cation 3.5.2.5 prior to any other reduction in shutdown margin by deboration or regulating rod withdrawal during the approach to criticality.

Bases At the beginning of life of the initial fuel cycle, the coderator temperature coefficient is expected to be slightly positive at eperating temperatures with -

the operating confiruration of control rods.(1)

Calculations show that above 525 F the positive noderator coefficient is acceptable.

I Since the noderator temperature coefficient at lower temperatures will be less negative or more positive than at operating tenperature,(2)_ startup and opera-l tion of the reactor when -reactor coolant temperature is less that 525 F is pro-hibited except where necessary for low power physics tests.

l The potential reactivity insertion due to the moderator pressure coeffi-cient(2)- that could result from depressuriting the coolant fron 2100 psia to saturation pressure of 900 psia is approximately 0.1 percent ak/k.

i l-During phys.ics tests, special operating precautions will be taken.

In addi-l

' tion, the strong negative Doppler coefficient (1) and the small integrated l

Ak/k would limit the magnitude of_ a power excursion resulting froa a reduc-i

~ tion of moderator: density.

The requirement that the reactor is not to 'be made critical belou DTT + 10 F provides-increased assurances -that the proper relationship between primary 1

. coolant pressure and temperatures-will be maintained relative.to the NDTT of

_the' primary coolant system. :Heatup to this ~ temperature will be accomplished L

lby operating the reactor _ coolant pumps.

t p

_21 8004250.

L

n If the shutdown nargin required by Specification 3.5.2 is maintained, ther.e is no possibility of an accidental criticality as a result of a decrease of coolant pressure.

The requirement for pressurizer bubble foruation and specified water level when the reactor is less that 1 percent subcritical uill assure that the reactor coolant system cannot become solid in the event of a rod withdrawal accident or a start-up accident and that the uater level is above the minimum detectable level.

The requirement that the safety rod groups be fully withdrawn before criticality ensures shutdown capability during startup.

This does not prohibit rod latch confirmation, i.e., withdrawal by group to a maxi-mua of 3 inches withdrawn of all seven groups prior to safety rod with-drawal.

The requirement for regulating rods being uithin their rod position limits ensures that the shutdown margin and ejected rod criteria at hot :ero power are not violated.

REFERE::CES (1)

FSAR, Section 3 (2)

FSAR, Section 3.2.2.1.5 t

22

OU k

i If a: control' rod in tl e regulating or axial power shaping groups 6

f is declared inoperable per Specifi catiom 4.7.1.2, operation above s.-

60 percent of the thermal power allowabic for the reacto' r coolant pump coirbination may continue _ providod' the rods in the group 'are positioned.such that the rodithat was declared inoperabic is main-tained within allowabic group average position limits of Specifi-cation 4.7.1.2.and the withdrawal limits of Specificatica 3.5.2.5.3.

3.5.2.3 The worth of singic inserted control rods during criticality are

limitedL by the restrictions _ of Specification 3.1.3.5 and the Control

~

-Rod Position Limits. defined in Specification 3.5.2.5.

3.5.2.4 1 Quadrant tilt:

1.

Except for physics tests, if quadrant tilt exceeds 4%, power shall -

be reduced immediately to below the power IcVel cutoff (sce Fig-urcs 3.5.2-1A, 3.5.2-1B, and 3.5.21C). Moreover, the power J evel l

cutoff value shall be reduced 24 for each 14 tilt in excess of the thermal power allowable for the reactor coolant pump combin-

. ation for each 1% tilt in' excess of 4%.

2.

I'lithin 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 re-duced to less than 4%, except for physics tests, or die following adjustments in setpoints. and limits shall be made:

The protection system maximum allowable'setpoints (Figure a.-

2.3-2) shall be reduced 2% in power for cach 1% tilt.

. b.

'Ihc control rod group withdrawal lindts (Figures 3.5.2-1A, 3.5.2-1B, and 3.5.2-1C) shall be reduced 2% in power for each l

1 L

1% tilt in excess of 4%.

She operational imbalance lindts (Figure 3.5.2-3) shall be c.

reduced 2% in power for each 1% tilt in excess of 4%.

I 3.

. If quadrant tilt is _ in excess of 25%, except for physics tests r

- or diagnostic testing, the reactor _will be placed in the hot

- shutdown conditio'n.

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 as stated in 3.5.2.4.1 above.

L 4.

Quadrant wit lshall be monitored ~on a minimum frequency of once

- every twL hours during power operation above 15#.- o f-ra t ed powe r.

3.5.2.5 Control ; rod positions :

1.. Technical Specification J3.1.3.5 '(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 Tech-nical Specification 3.5.2.2.

2.

Operating.r' d groupj overlap shall b'c 25% ;5 between two sequen-o tial! groups,;cxcept for-physics tests.

47 Y

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lixcept for physics tes t s or exercising control rods, the control rod withdrawal linits are specified on Fi;;ures 3.5.2-I A, 3. 5.2-M, and 3.5.2-1C for four pump operation and on Fi pare 3.5.2-2 for l

t three or two pump operation.

If the control rod position li:aits are exceeded, corrective measures shall be taken immediately to achieve an acceptable control rod position.

Acceptable control rod positions 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) tulless the xenon reactivity is within 10 percent of the equilibriuta value for oper-ation at rated power and asymptotically approaching stability.

3.5.2.6 Reactor Power Ir.halance shall be monitored on a frequency not to ex-coed two hours during power operation above 40 percent rated power.

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

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

If an acceptable imbalance is not achieved within four hours, reactor power shall be reduced until imbalance limits are met.

3.5.2.7 The control rod drive patch panels shall be locked at all times with

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limited access to be authorized by the superintendent.

l Bases l

'Ihe power-imbalance envelope defined in Figure 3.5.2-3 is based on LOCA an-alyses which have defined the maximtua linear heat rate (see Figure 3.5.2-4) such that the maximum clad temperature will not exceed the Interim Acceptance Cri te ri a.

Corrective measures will be taken irrediately should the indicated quadrant tilt, rod powition, or imbalance be outside their specified boundary.

Operation in a situation that would cause the Interim 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 their limits while simultaneously all other engineering and uncertainty at factors are also at their limits.* Conservatism is introduced by application of:

a.

Nuclear uncertainty factors b.

Thermal calibration c.

Fuel densification effects

d. -llot rod manufacturing tolerance factors

'lhe 25 percent 15 percent overlap be tween successi ve con t rol rod "roops i :,

allowed since the worth of a rod is lower at the upper and lower part of the s t roke. 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 instrtuacnt and calibration errors.

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

48 L

Group -

Functi'on 1

Safety 2

Safety 3

Safcty 4'

Safety 5

Regulating

'6 Regulating 7

Xenon transient override 8

APSR.(axial power shaping bank)

The rod position limits are based on the most limiting of the following three 'critoria: ECCS powe'r.pcaking, shutdown margin, and potential l

' cjected red worth. As discussed above, compliance with the ECCS power i

peaking. criterion is ensured by the rod position limits.

The minimum i

availabic rod worth, consistant with the rod position lirdts, provides j

for achieving ~ hot shutdown by reactor trip at any time, assuming the highest worth control rod that is withdrawn remains in the full out posi-

'ti on.'(1).

The rod position limits also ensure that inserted rod groups will not contain singic rod worths greater than 0.65% ak/k at rated power.

These values have been shown to be safe by the safety analysis -(2) of the hypothetical roll ejection ~ accident.

A maximum single inserted control crod worth of 1.0% ak/k is allowed by the rod positions linits at hot zero

[

power.

A singic inserted control rod worth of-1.0% Ak/k at beginning of life, hot, zero power would result in-a lower transient peak thermal power-and,- therefore, less seve.e environmental consequences tl'an a 0.65% ak/k ejected rod worth at-rated power.

i

' Control ro~d groups are withdrawn in sequence beginning with group 1.

Groups 5, 6, and.7 are-overlapped 25%.

The normal position at power is for groups i

6 and 7_to be partially inserted.

The quadrant power tilt limits set forth in Specificarion 3.5.2.4 have been l

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

'lhese' limits in. conjtutetion with the control. rod position limits in Specif-l

.icatioiL3.5.2.5.3 cnsure that design peak heat rate cri t eria are not exceeded during normal operatioit. when ' including the effects of' pot ential fuel dens i-fication'.

llio q'uadrant tilt and axial imbalance monitoring in Specifications 3.5.2.4' 6 l

and 3.5.2.5.4, respectively,: will normally be performed in the plant com-

.puter.

The two, hour. frequency for monitoring these quantitics will provide i

adequate' surveillance.when, the computer is out of service.

l During the; physics testing -program, the. high flux trip setpoints' are adminis-tratively; set as follows to ensure that an additional safety margin is pro-

vided:

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1

]1.Ridindes is_the per ntagr: r.um of t he wi t hd rawal o f tt.c ut -.iting r;roop s.

2. Restrictions on witharawal (hashed creas) are modified af ter the control, roc interchange (Sec Figure 3.5 2 1 B)

(125,102)

(194,102)

(242,102) 102 100 RESTRICTED

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REGION

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80 _ 82.5

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(182.9,87.5)

(262.7,82.5) ~

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PERkiSSIBLE

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0 50 100 150 200 250 300 Rod Index. G i'iithdrawsl 0

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I Group 5 ARKANSAS PCNiiR G LIGl!T CO.

CONTROL ROD' GROUP WI'llibRANAL I;1G. NO.

ARKANSAS NUCIIAR ONE-UNIT 1 LI!!ITS FOR4_ PUMP OPERATION 3.5.2-1A 1%

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Rea index is th ercentage s:: of the withdra=.

of the

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2.

The additional restrictions on -ithdra.al (nashed areas) are in ef fect af ter the control rod intercnange.

The restrictions on witndrawal are further codified after 435 full acwe r day s of opera tion (See Figure 3.5.2-IC)

(lG2 iC2)

(194,102)

(242,192)

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Graus 5 ARKANSAS P0lGR G LIGilT CO.

CONTROL ROD GROUP WITIIDRANAL EIG. NO.

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

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Rod.indes is t pe rcon tage r u ra of the withara-of the operating groups.

2.

The additional restrictions on wi thd raw al are in effect after '435 full power days of operation.

(270, 102) (291.',

4 102) 102 100 (162,102) j

- 82.5 (303,82.5) f4 (2n.5,82.5) 80 y

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Group 5 ARKA'iSAS POWER 6 LIGHT CO.

CONTROL ROD GROUP WIHIDRAUAL FIG. 50.

ARKANSAS IiUCLEAR OSE-UNIT 1 LD1ITS FOR 4 PUMP OPERATION 3.5.2-1C 10,3

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ADDITIONAL RESTRICTIO"S ARE REQUIRED FOLL0tlING CONTROL ROD INTERCIIANGE (SEE FIGURE 3.5.2-2A).

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REGION o 80 a:

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Gicup 5 ARKANSAS P0flER &'llG'HT CO.

CONTROL.R00~ GROUP WITHORAWAL' FIG.HO.

ARKANSAS NUCLEAR ONE UNIT 1 LIMITS FOR.3 AND-2 PUMP OPERATION

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v.

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c u

a 0

1.

20D INDL. IS THE rERCENTAGE SUM 0F THE b, itDRAWAL OF THE OPERATING GROUPS.

2.

TiiESE P".STRICTIONS api'LY FOLLO't.'ING CONTROL ROD INTERCl!AN~4E.

( is.".;, ica )

-402 100 f(177.4.102)

S PE R ATION IN THIS REGION f

IS NOT ALLOWED

=

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80 P E Ril l S S I B LE E

A OPERATlHG f.

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REGION O

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' ARKANSAS POWER S LIGi!T CO.

CONTROL ROD GROUP WITilDRANAL FIG. NO.

-ARKANSAS NUCLEAR ONE-UNIT 1 1.I5!ITS FOR 3 AND 2 pud!P OPERATION 3.5.2-2A i o.

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