ML20132F347

Proposed Tech Specs Improving Sections TS 15.3.10, Control Rod & Power Distribution Limits & TS 15.4.1, Operational Safety Review

ML20132F347
Person / Time
Site:	Point Beach
Issue date:	12/19/1996
From:	WISCONSIN ELECTRIC POWER CO.
To:
Shared Package
ML20132F340	List: ML20132F335 ML20132F347
References
NUDOCS 9612240202
Download: ML20132F347 (23)

Text

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I 15.3.10 CONTROL ROD AND POWER DISTRIBUTION LIMITS Aeolicability Applies to the operation of the control rods and to core power distribution limits.

Objective To insure (1) core suberiticality after a reactor trip, (2) a limit on potential reactivity insertions from a hypothetical rod cluster control assembly (RCCA) ejection, and (3) an acceptable core power distribution during power operation.

l l

l Soecification l lA. SHUTDOWN MARGIN

! 1. The shutdown margin shall exceed the applicable value as shown in Figure 15.3.10-2 under all steady-state operating conditions from 350 F to full power. If the shutdown margin is less than the applicable value of Figure 15.3.10-2. within l 15 minutes initiate boration to restore the shutdown margin.

l 2. A shutdown margin of at least 1% Ak/k shall be maintained when the reactor l- coolant temperature is less than 350 F. If the shutdown margin is less than this

( limit, within 15 minutes initiate boration to restore the shutdown margin.

lB. ROD OPERABILITY AND BANK ALIGNMENT LIMITS E

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1. During power and low power operation, all shutdown and control rods shall be i operable, with all individual indicated rod positions within twelve steps of their I bank demand position, except when the bank demand position is 530 steps or  !

2:215 steps. In this case, all individual indicated rod positions shall be within 24 I l steps of their bank demand position.

If an RCCA does not step in upon demand, up to six hours is allowed to determine whether the problem with stepping is an electrical problem.' If the l problem cannot be resolved within six hours, the RCCA shall be declared inoperable until it has been verified that it will step in or would drop upon l demand.

a. Rod Ooerability Reauirements

! (1) If one rod is determined to be untrippable, perform the following

! actions:

9612240202 961219 PDR ADOCK 05000266 P PM ,

Unit 1 - Amendment No. 15.3.10-1 Unit 2 - Amendment No.

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i (a) Within one hour verify that the shutdown margin exceeds  !

I the applicable value as shown in Figure 15.3.10-2; M i (b) Within one hour restore the shutdown margin by boration:

l M i l (c) Within six hours be in hot shutdown. -

L (2) If sustained power operation with an untrippable rod is desired. ,

perform the following actions:

(a) Within one hour verify that the shutdown margin exceeds  !

L the applicable value as shown in Figure 15.3.10-2; M I l- within one hour restore the shutdown margin by boration:

M (b) Within six hours, adjust the insertion limits to reflect the worth of the untrippable rod.  !

l (c) If the above actions and associated completion times are ,

not met, be in hot shutdown within six hours.

1 (3) If more than one rod is determined to be untrippable, perform the following actions:

(a) . Within one hour verify that the shutdown margin exceeds )

the applicable value as shown in Figure 15.3.10-2; M within one hour restore the shutdown margin by boration:

M (b) Within six hours be in hot shutdowm.

b. Rod Bank Alignment Limits (1) Ifit has been determined that one rod is not within alignment limits, and the indicated misalignment is not being caused by malfunctioning rod position indication, within one hour restore the rod to within alignment limits; M perform the following actions:

(a) Within one hour verify that the shutdown margin exceeds the applicable value as shown in Figure 15.3.10-2; M l within one hour restore the shutdown margin by boration:

M (b) Within eight hours reduce thermal power to 575 percent of rated thermal power; AND Unit 1 - Amendment No. 15.3.10-2 Unit 2 - Amendment No.

i

(c) Verify that the shutdown margin exceeds the applicable value as shown in Figure 15.3.10-2 once per twelve hours; M

(d) Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> verify that measured values of En(Z) are within limits; M

(e) Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> verify that F% is within limits; l

(f) If the above actions and associated completion times are not met, be in hot shutdown within the following six hours.

(g) In order to subsequently increase thermal power above 75 percent of rated thermal power with the existing rod misalignment, perform an analysis to determine the hot '

channel factors and the resulting allowable power level in accordance with TS 15.3.10.E.

I (2) Ifit has been determined that more than one rod is not within alignment limits and the misalignments are not being caused by malfunctioning rod position indication. perform the following l actions:

(a) Within one hour verify that the shutdown margin exceeds the applicable value as shown in Figure 15.3.10-2; OR within one hour restore the shutdown margin by boration; AND (b) Be in hot shutdown within six hours.

C. ROD POSITION INDICATION 1

NOTE: Separate entry into TS 15.3.10.C.I.a. b, or e is allowed for each inoperable j rod position indicator and each bank of demand position indication.  ;

1. During power operation 2:10 percent of rated thermal power, the rod position indication system and the bank demand position indication system shall be operable.

a. If one or more rod position indicators (RPI) are determined to be inoperable, perform the following actions:

(1) Within eight hours verify the position of the rods with inoperable RPIs by using movable incore detectors; AND Unit 1 - Amendment No. 15.3.10-3 Unit 2 - Amendment No.

l (2) Once per shift check the position of the rods with inoperable RPIs l by using excore detectors, or thermocouples, or movable incore l detectors; (3) If the above actions and associated completion times are not met, l perform the actions in accordance with TS 15.3.10.B.I.b.

l l b. If one or more rods with inoperable RPIs have been moved in excess of 24 l steps in one direction since the last determination of the rod's position, l perform the following actions:

I (1) Within four hours check the position of the rods with inoperable RPIs by using excore detectors, or thermocouples, or movable incore detectors; (2) If the above action and associated completion time is not met, perform the actions in accordance with TS 15.3.10.B.I.b.

c. If bcnk demand position indication, for one or more banks, is determined to be inoperable, perform the following actions:

1 (1) Once per shift verify that all RPIs for the affected banks are operable; AND (2) Once per shift verify that the most withdrawn rod and the least withdrawn rod of the affected banks are s12 steps apart, except when the bank demand position is s30 steps or 2215 steps. In this case, once per shift verify that the most withdrawn rod and the i least withdrawn rod of the affected banks are s24 steps apart: j (3) If the above actions and associated completion times are not met.

perform the actions in accordance with TS 15.3.10.B.I.b.

lD. B ANK INSERTION LIMITS

1. When the reactor is critical, the shutdown banks shall be fully withdrawn. Fully withdrawn is defined as a bank position equal to or greater than 225 steps. This definition is applicable to shutdown and control banks.

If this condition is not met, perform the following actions:

i l a. Within one hour verify that the shutdown margin exceeds the applicable j value as shown in Figure 15.3.10-2; QR within one hour restore the shutdown margin by boration; i

Unit 1 - Amendment No. 15.3.10-4 Unit 2 - Amendment No.

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AND  !

b. Within two hours fully withdraw the shutdown banks.

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c. If the above actions and associated completion times are not met, be in hot j shutdown within the following six hours. I

2. When the reactor is critical, the control banks shall be inserted no further than the limits shown by the lines on Figure 15.3.10-1. If this condition is not met, perform the following actions:

a. Within one hour verify that the shutdown margin exceeds the applicable value as shown in Figure 15.3.10-2; OR within one hour restore the shutdown margin by boration; AND

b. Within two hours restore the control banks to within limits.

c. If the above actions and associated completion times are not met, be in hot shutdown within the following six hours.

l E. POWER DISTRIBUTION LIMITS l 1. Hot Channel Factors l a. The hot channel factors defined in the basis shall meet the following limits:

Fy(Z) S (2.50) x K(Z) for P > 0.5 p

Fo(Z) S 5.00 x K (Z) for P S 0.5 Phu < l.70 x [l + 0.3 (1-P)]

Where P is the fraction of full power at which the core is operating, K(Z) is the function in Figure 15.3.10-3 and Z is the core height location of Fq.

b. If F n(Z) exceeds the limit of Specification 15.3.10.E.1.a within fifteen minutes reduce thermal power until F9(Z) limits are satisfied; (1) After thermal power has been reduced in accordance with Specification 15.3.10.E.1.b, perform the following actions:

Unit 1 - Amendment No. 15.3.10-5 Unit 2 - Amendment No.

i (a) Within eight hours reduce the full power Power Range  !

Neutron Flux - High trip setpoints by an amount equivalent to the power reduction required in Specification i 15.3.10.E.1.b: -

I M t (b) Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> reduce Overpower and Overtemperature AT trip setpoints by an amount equivalent to the power i reduction required in Specification 15.3.10.E.1.b; M

(c) Verify that Fn(Z) will be within limits for the increased power level prior to increasing any setpoints that have been reduced and thermal power above the limit specified in 1 Specification 15.3.10.E.1.b.

l (d) If the above actions and associated completion times are ,

not met, be in low power operation within the following six '

hours. i

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c. If F a3 exceeds the limit of Specification 15.3.10.E.1.a. within four hours N l reduce thermal power to restore F AHt o within limits OR perform the i following actions:

(1) Within four hours reduce thermal power to 550 percent rated thermal power; i AND

(2) Within eight hours reduce the full power Power Range Neutron Flux - High trip setpoints to $58 percent rated thermal power.

In addition to the above actions, the following actions shall also be N

performed during the subsequent power escalation if F sg had exceeded l the limit of Specification 15.3.10.E.1.a:

N (3) Verify that F 3n is within limits within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />; M

(4) Verify that F"3n is within limits prior to thermal power exceeding j 50 percent of rated thermal power; M

(5) Verify that F"3n is within limits prior to thermal power exceeding 75 percent of rated thermal power; AND (6) Verify that F"3s is within limits within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after reaching 295

. percent of rated thermal power.

Unit 1 - Amendment No. 15.3.10-6 Unit 2 - Amendment No.

(7) If the above actions and associated completion times are not met, ,

be in hot shutdown within the following six hours.  ;

2. Axial Flux Difference NOTE: The axial flux difference shall be considered outside limits when two or more operable excore channels indicate that axial flux difference is outside limits.

a. During power operation with thermal power 250 percent of rated thermal power, the axial flux difference shall be maintained within the limits specified in Figure 15.3.10-4.

(1) If the axial ilux difference is not within limits, within 15 minutes restore to within limits. If this action and associated completion time is not met, perform the following actions:

(a) Reduce thermal power until the axial flux difference is within limits; >

DR (b) Within three hours reduce thermal power to s50 percent of rated thermal power.  :

b. Ifit is necessary to restrict thermal power to s50 percent of rated thermal power, within the next four hours reduce the Power Range Neutron Flux -

High Trip setpoints to s55 percent.  ;

c. If the alarms used to monitor the axial flux difference are rendered inoperable, verify that the axial flux difference is within limits for each operable excore channel once within one hour and every hour thereafter.

l 3. Ouadrant Power Tilt l

a. During power operation with thermal power greater than 50 percent of rated thermal power, the indicated quadrant power tilt shall not exceed 2 percent. If this condition is not met, perform the following actions:

(1) Within two hours, reduce thermal power 22 percent from rated thermal power for each I percent ofindicated quadrant power tilt:

M (2) Within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and once per seven days thereafter. verify that i Fn(Z) and F% are within the limits of Specification 15.3.10.E.1.a; M

Unit 1 - Amendment No. 15.3.10-7 Unit 2 - Amendment No.

(3) Reevaluate safety analyses and confirm results remain valid for duration of operation under this condition. This action shall be  !

completed prior to increasing themial power above the limit imposed by Specification 15.3.10.E.3.a.(1).

(4) Upon completion of Specification 15.3.10.E.3.a.(3), calibrate the excore detectors. This action shall be completed prior to increasing thermal power above the limit imposed by Specification 15.3.10.E.3.a.(1);

i AND (5) Verify that Fn(Z) and F% are within the limits of Specification 15.3.10.E.1.a within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after reaching rated thermal power, or within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after increasing thermal power above the limit imposed by Specification 15.3.10.E.3.a.(1).

(6) If the above actions and associated completion times are not met, within the following four hours reduce thermal power to s50 percent of rated thermal power.

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b. If no quadrant power tilt alarms are available, within twelve hours and

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every twelve hours thereafter, verify that quadrant power tilt is within J limits by performing calculations.

c. When one power range channel is inoperable and thermal power is greater  !

than 75% of rated thermal power, within twelve hours and every twelve hours thereafter, verify that quadrant power tilt is within limits by use of I the movable incore detectors.

F. AT-POWER PHYSICS TESTS EXCEPTIONS

1. During the performance of at-power physics tests, the requirements of:

l Specification 15.3.10.B " Rod Operability and Bank Alignment Limits" Specification 15.3.10.D," Bank Insertion Limits" l

Specification 15.3.10.E.2, " Axial Flux Difference" '

specification 15.3.10.E.3, " Quadrant Power Tilt" are suspended, provided:

l a. Thermal power is maintained 585 percent of rated thermal power; l AND

b. Power Range Neutron Flux - liigh Trip setpoints are set at a maximum setting of 90 percent of rated thermal power;

( Unit 1 - Amendment No. 15.3.10-8 l

l Unit 2 - Amendment No.

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2. Within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to the initiation of physics tests, verify that Power Range Neutron Flux - liigh Trip setpoints are s90 percent of rated thermal power.

3. If the shutdown margin is not within the limits of Specification 15.3.10.A.1, within 15 minutes initiate boration to restore the shutdown margin, AND within one hour suspend physics tests exceptions.

4. If thermal power exceeds 85 percent of rated thermal power, within one hour reduce thermal power to s85 percent of rated thermal power, OR within one hour  ;

suspend physics tests exceptions.

5. If the Power Range Neutron Flux - High Trip setpoints are greater than 90 percent of rated thermal power, within one hour restore the Power Range Neutron Flux -

High Trip setpoints to s90 percent of rated thermal power, OR within one hour suspend physics tests exceptions.

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6. Every hour, while at-power physics tests are in progress, verify that thermal power is 585 percent of rated thermal power.

7. At least once every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, verify Fn (Z) and F% are within the required limits.

G. LOW POWER PHYSICS TESTS EXCEPTIONS

1. During the performance oflow power physics tests, the requirements of:

Specification 15.3.10.B," Rod Operability and Bank Alignment Limits" Specification 15.3.10.D, " Bank Insertion Limits" l

l Specification 15.3.10.E, " Power Distribution Limits"

)

are suspended, provided the lowest RCS loop average temperature is greater than l the minimum temperature for criticality.

2. If the shutdown margin is not within the limits of Specification 15.3.10.A, within

! 15 minutes initiate boration to restore the shutdown margin, AND within one hour suspend physics tests exceptions.

3. If power is not within limits, open the reactor trip breakers immediately.

r i 4. Iflowest RCS loop average temperature is less than the minimum temperature fbr  ;

i criticality, within 15 minutes restore lowest RCS loop average temperature to l within limits, OR within 30 minutes be suberitical.

4

. Unit 1 - Amendment No. 15.3.10-9 Unit 2 - Amendment No.

lH. RCCA DROP TIMES

1. With RCS temperature greater than the minimum temperature for criticality and with both reactor coolant pumps mnning, the drop time of each RCCA shall be no greater than 2.2 seconds from the loss of stationary gripper coil voltage to dashpot entry. If this condition is not met, perform the following actions:

a. If the reactor is critical, declare the rod untrippable; D.R

b. If the reactor is suberitical, maintain the reactor suberitical.

Basis Insertion Limits and Shutdown Marcin During power operation, the shutdown banks are fully withdrawn. Fully withdrawn is defined as

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a bank demand position equal to or greater than 225 steps. Evaluation has shown that I positioning control rods at 225 steps, or greater, has a negligible effect on core power distributions and peaking factors. Due to the low reactivity worth in this region of the core and the fact that, at 225 steps, control rods are only inserted one step into the active fuel region of the core, positioning rods at this position or higher has minimal effect. This position is varied, based l on a predetermined schedule, in order to minimize wear of the RCCA's from the guide cards.

The control rod insertion limits provide for achieving hot shutdown by reactor trip at any time i and assume the highest worth control rod remains fully withdrawn. A 10% margin in reactivity I worth of the control rods is included to assure meeting the assumptions used in the accident l analysis. A reactor trip occurring during power operation places the reactor into hot shutdown.

In addition, the insertion limits provide a limit on the maximum inserted rod worth in the L unlikely event of a hypothetical rod ejection and provide for acceptable nuclear peaking factors.

The specified control rod insertion limits take into account the effects of fuel densification. The rods are withdrawn in the sequence of A, B, C, D with overlap between banks. The overlap between successive control banks is provided to compensate for the low differential rod worth near the top and bottom of the core.

When the insertion limits are observed and the control rod banks are above the solid lines shown on Figure 15.3.10-1, the shutdown requirement is met. The maximum shutdown margin requirement occurs at end of core life and is based on the value used in analysis of the hypothetical steam break accident. Figure 15.3.10-2 shows the shutdown margin equivalent to 2.77% reactivity at end-of-life with respect to an uncontrolled cooldown. All other accident I analyses assume 1% or greater reactivity shutdown margin. Shutdown margin calculations l l include the effects of axial power distribution. The accident analyses assume no change in core poisoning due to xenon, samarium or soluble boron.

1 l Unit 1 - Amendment Nc 15.3.10-10 F

Unit 2 - Amendment No.

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If the shutdown margin requirements are not met, boration must be initiated promptly. Fifteen minutes is an adequate period of time for an operator to correctly align and start the required systems and components. It is assumed that boration will be continued until shutdown margin requirements are met.

Rod Onerability Reauirements and Bank Alienment Limits The operability (e.g. trippability) of the shutdown and control rods is an initial assumption in all safety analyses that take credit for rod insertion upon reactor trip. Maximum rod misalignment is also an initial assumption in the safety analyses that directly affect core power distributions and assumptions of available shutdown margin. A rod cluster control assembly (RCCA) shall be considered operable if the RCCA drops upon removal of stationary gripper coil voltage.

Mechanical or electrical failures may cause a control rod to beccme inoperable or to become misaligned from its group. Control rod inoperability or misalignment may cause increased power peaking due to the asymmetric reactivity distribution. This uilt also cause a reduction in the total available rod worth for reactor shutdown. Therefore, control rod alignment and i operability are related to core operation in design power peaking limits and the core design ,

requirement of a minimum shutdown margm.  ;

i From operating experience to date, an RCCA which steps in properly will drop when a trip signal  ;

occurs because the only force acting to drive the rod in is gravity. When it has been determined  !

that a rod does not drop, the shutdown margin calculation will need to include the worth of the l inoperable control rod. Further experience indicates that control rods which do not step are i usually affected by electrical problems. That is, normally the problem is in the rod control l cabinets.  !

Rod cluster control assemblies (RCCAs), or rods, are moved by their control rod drive mechanisms (CRDMs). Each CRDM moves its RCCA one step (approximately 5/8 inch) at a time, but at varying rates (steps per minute) depending on the signal output from the Rod Control l System.

The RCCAs are divided among control banks and shutdown banks. A group consists of two or more RCCAs that are electrically paralleled to step simultaneously. A bank of RCCAs consists of one or two groups that are moved in staggered fashion. but always within one step of each other. Each unit has four control banks and two shutdown banks.

When one or more rods are determined to be untrippable, there is a possibility that the required shutdown margin may be adversely affected. Under these conditions, it is important to determine the shutdown margin, and ifit is less than the required value, initiate boration until the required shutdown margin is restored. The one-hour ume limit is adequate for determining the shutdown margin and, if necessary. for restoring the shutdown margin by boration. In this situation, shutdown margin verification must include the worth of the untrippable rod, as well as a rod of maximum worth.

Unit 1 - Amendment No. 15.3.10-11 Unit 2 - Amendment No.

l If the untrippable rods cannot be restored to an operable condition, the plant must be placed in a condition where the LCO requirements are not applicable. To achieve this status, the unit must be placed in hot shutdown within six hours. This allows this plant condition to be reached in an orderly manner, without challenging any plant systems.

Limits on control rod alignment have been established and all rod positions are monitored and controlled during power operation to ensure that the power distribution and reactivity limits defined by the design power peaking and shutdown margin limits are preserved.

If the misalignment condition cannot be readily corrected, thermal power will be adjusted so that hot channel factors are maintained, and so that the requirements on shutdown margin and ejected rod worth are preserved. Continued operation of the reactor with a misaligned control rod is allowed if En(Z) and F% are verified to be within their limits. When a control rod is misaligned, the assumptions that are used to determine the rod insertion limits, axial flux difference limits, and quadrant power tilt limits are not preserved. Therefore, the limits may not preserve the design peaking factors and Fn (Z) and F"3s must be verified directly by incore mapping.

Upon detection of a potential problem concerning one or more rods, a maximum of six hours is provided for troubleshooting activities. Immediately upon determining that one or more rods is inoperable, the applicable actions in TS 15.3.10.B shall be perfonned. If after six hours, an operability determination has not yet been made. the rod (s) shall be declared inoperable and the applicable actions in TS 15.3.10.B shall be performed.

Rod Position Indication During power operation at greater than ten percent of rated thermal power, the rod position indication system and the bank demand position indication system are required to be operable. l These systems are required to be operable because the position of rods must be determined in order to ensure that rod alignment and insertion limits are being satisfied. Rod position accuracy is essential during power operations. Power peaking, ejected rod worth, or shutdown margin limits may be violated in the event of a design basis accident with rods operating, undetected, outside of their required limits.

The various control rod banks (shutdown banks and control banks, A, B, C, and D) are each to be moved as a bank; that is, with all rods in the bank within one step (5/8 inch) of the bank position.

Direct information on rod position indication is provided by two methods: A digital count of actuating pulses which shows the demand position of the banks and a linear position indicator (LVDT) which indicates the actual rod position. The rod position indicator channel has a l demonstrated accuracy of 5% of span (*11.5 steps). Therefore, an analysis has been performed l to show that a misalignment of 24 steps cannot cause design hot channel factors to be exceeded.

A single fully misaligned RCCA, that is, an RCCA 230 steps out of alignment with its bank.

l does not result in exceeding core limits in steady-state operation at power levels less than or equal to rated power. In other words, a single dropped RCCA is allowable from a core power

! Unit 1 - Amendment No. 15.3.10-12 Unit 2 - Amendment No. -

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distribution viewpoint. If the misalignment condition cannot be readily conected, the specified reduction in power to 75% will insure that design margins to core limits will be maintained under both steady-state and anticipated transient conditions. The eight (8) hour permissible limit on rod misalignment at rated power is short with respect to the probability of an independent accident.

l Because the rod position indicator system may have a 12 step error when a misalignment of 24 steps is occurring, the Specification allows only an indicated misalignment of 12 steps.

However, when the bank demand position is greater than or equal to 215 steps, or, less than or equal to 30 steps, the consequences of a misalignment are much less severe. The differential worth of an individual RCCA is less, and the resultant perturbation on power distributions is less than when the bank is in its high differential worth region. At the top and bottom of the core, an indicated 24 step misalignment may be representing an actual misalignment of 30 steps.

The failure of an LVDT in itself does not reduce the shutdown capability of the rods, but it does reduce the operator's capability for determining the position of that rod by direct means. The  ;

operator has available to him the excore detector recordings, incore thermocouple readings and periodic incore flux traces for indirectly determining rod position and flux tilts should the rod l with the inoperable LVDT become malpositioned. The excore and incore instrumentation will not necessarily recognize a misalignment of 24 steps because the concomitant increase in power density will normally be less than 1% for a 24 step misalignment. The excore and incore instrumentation will, however, detect any rod misalignment which is sufficient to cause a l l significant increase in hot channel factors and/or any significant loss in shutdown capability.

l The increased surveillance of the core if one or more rod position indicator channels is out-of-service serves to guard against any significant loss in shutdown margin or raargin to core thermal

, limits.

l The history of malpositioned RCCA's indicates that in nearly all such cases, the malpositioning l occurred during bank movement. Checking rod position after bank motion exceeds 24 steps will l verify that the RCCA with the inoperable LVDT is moving properly with its bank and the bank step counter. Malpositioning of an RCCA in a stationary bank is very rare, and ifit does occur, it is usually gross slippage which will be seen by extemal detectors. Should it go undetected, the l time between the rod position checks performed every shift is short with respect to the probability of occurrence of another independent undetected situation which would further reduce the shutdown capability of the rods.

Any combination of misaligned rods below 10% rated power will not exceed the design limits.

For this reason, it is not necessary to check the position of rods with inoperable LVDT's below 10% power; plus, the incore instrumentation is not effective for determining rod position until the power level is above approximately 5%.

1 Unit 1 - Amendment No. 15.3.10-13 Unit 2 - Amendment No.

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l Power Distribution During power operation. the global power distribution is limited by TS 15.3.10.E.2, " Axial Flux i Difference," and TS 15.3.10.E.3, " Quadrant Power Tilt," which are directly and continuously l l measured process variables. These specifications, along with TS 15.3.10.D, " Bank Insertion j Limits." maintain the core limits on power distributions on a continuous basis.

l l The purpose of the limits on the values of F n(Z), the height dependent heat Dux hot channel ,

factor. is to limit the local peak power density. The value of Fn(Z) varies along the axial height (Z) of the core.

En(Z) is denned as the maximum local fuel rod linear power density divided by the average fuel rod linear power density, assuming nominal fuel pellet and fuel rod dimensions. Therefore, Fn(Z) is a measure of the peak fuel pellet power within the reactor core.

Fn(Z) varies with fuel loading patterns, control bank insertion, fuel burnup, and changes in axial power distribution. F (Z) n is measured periodically using the incore detector system. These measurements are generally taken with the core at or near steady state conditions.

The purpose of the limits on F*3n, the nuclear enthalpy rise hot channel factor, is to ensure that the fuel design criteria are not exceded and the accident analysis assumptions remain valid. The design limits on local and integrated fuel rod peak power density are expressed in te .as of hot channel factors. Control of the core power distribution with respect to these factors ensures that local conditions in the fuel rods and coolant channels do not challenge core integrity at any location during either normal operation or a postulated accident analyzed in the safety analyses.

F*an, Nuclear Enthalpy Rise Hot Channel Factor, is defined as the ratio of the integral oflinear power along a fuel rod to the average fuel rod power. Imposed limits pertain to the maximum F"3a in the core, that is the fuel rod with the highest integrated power. It should be noted that j F"3a is based on an integral and is used as such in the DNB calculations. Local heat flux is I obtained by using hot channel and adjacent channel explicit power shapes which take into account variations in horizontal (x-y) power shapes throughout the core. Thus, the horizontal  ;

power shape at the point of maximum heat flux is not necessarily directly related to F*an. I F"an is sensitive to fuel loading patterns, bank insertion, and fuel burnup. F"3n typically increases with control bank insertion and typically decreases with fuel burnup.

N F 3n is not directly measurable but is inferred from a power distribution map obtained with the movable incore detector system. Specifically, the results of the three dimensional power distribution map are analyzed by a computer to determine F*3n. This factor is calculated at least monthly. However. during power operation, the global power distribution is monitored by TS 15.3.10.E.2, " Axial Flux Difference," and TS 15.3.10.E.3, " Quadrant Power Tilt." which address directly and continuously measured process variables.

l Unit 1 - Amendment No. 15.3.10-14 Unit 2 - Amendment No.

i l It has been determined that, provided the following conditions are observed, the hot channel l factor limits will be met:

l

1. Control rods in a single bank move together with no individual rod insertion differing by more than 24 steps from the bank demand position, when the bank demand position is between 30 steps and 215 steps. A misalignment of 36 steps is allowed when the bank  ;

l position is less than or equal to 30 steps, or, when the bank position is greater than or equal to 215 steps, due to the small worth and consequential effects of an individual rod misalignment. l

2. Control rod banks are sequenced with overlapping banks as described in Figure 15.3.10-1.

l3. Control bank insertion limits are not violated.  ;

4. Axial power distribution control procedures, which are given in terms of flux difference control and control bank insertion limits, are observed. Flux difference refers to the difference in signals between the top and bottom halves of two-section excore neutron detectors. The flux difference is a measure of the axial offset which is defined as the difference in normalized power between the top and bottom halves of the core.

N The permitted relaxation of F aH allows radial power shape changes with rod insertion to the insertion limits. It has been determined that provided the above four conditions are observed, i these hot channel factor limits are met. In Specification 15.3.10.E.1.a, Fn is arbitrarily limited for p s 0.5.

An upper bound envelope of 2.50 times the normalized peaking factor axial dependence of Figure 15.3.10-3 consistent with the Technical Specifications on power distribution control as given in Section 15.3.10 was used in the large and small break LOCA analyses. The envelope was determined based on allowable power density distributions at full power restricted to axial l flux difference (AI) values consistent with those in Specification 15.3.10.E.2, The results of the analyses based on this upper bound envelope indicate a peak clad temperature ofless than the 2200 F limit. When an Fq measurement is taken, both experimental error and l manufacturing tolerance must be taken into account. Five percent is the appropriate allowance for a full core map taken with the moveable incore detector flux mapping system and three percent is the appropriate allowance for manufacturing tolerance. In the design limit of F"3n, there is eight percent allowance for uncertainties wrich means that normal operation of the core is expected to result in a design F"3a s 1.70/1.08 The logic behind the larger uncertainty in this j case is as follows:

(a) Normal perturbations in the radial power shape (i.e., rod misalignment) affect F"3n. in most cases without necessarily affecting Fn.

Unit 1 - Amendment No. 15.3.10-15 Unit 2 - Amendment No.

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(b) While the operator has a direct influenceoon F through movement of rods, and can limit it to the desired value, he has no direct control over F 3s.

(c) An error in the predictions for radial power shape which may be detected during startup physics tests can be compensated for in Fo by tighter axial control; but compensation for F 3a is less readily available, i

l Measurements of the hot channel factors are required as part of startup physics tests, at least each j full power month operation, and whenever abnormal power distribution conditions require a l reduction of core power to a level based upon measured hot channel factors. The incore map taken following initial loading provides confirmation of the basic nuclear design bases including

proper fuel loading pattems. The periodic monthly incore mapping provides additional l assurance that the nuclear design bases remain inviolate and identify operational anomalies which would, otherwise, affect these bases.

The measured hot channel factors are increased as follows: l (a) The measurement of total peaking factor, F9 "" shall be increased by three percent to l account for manufacturing tolerance and further increased by five percent to account for measurement error.

N (b) The measurement of enthalpy rise hot channel factor, F AH shall be increased by four percent to account for measurement error.

Axial Power Distribution The limits on axial flux difference (AFD) assure that the axial power distribution is maintained such that the Fn (Z) upper bound envelope of Fn" times the normalized axial peaking factor (K(Z)] is not exceeded during either normal operation or in the event of xenon redistribution following power changes. This ensures that the power distributions assumed in the large and small break LOCA analyses will bound those that occur during plant operation.

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 AFD for each of the  !

operable excore channels and provides a computer alarm if the AFD for at least 2 of 4 or 2 of 3 operable excore channels are outside the AFD limits and the reactor power is greater than 50 percent of Rated Power.

Ouadrant Tilt l

The quadrant tilt limit ensures that the gross radial power distribution remains consistent with the l design values used in the safety analyses. Precise radial power distribution measurements are made during startup testing, after refueling, and periodically during power operation.

Unit 1 - Amendment No. 15.3.10-16 Unit 2 - Amendment No.

The power density at any point in the core must be limited so that the fuel design criteria are i maintained. Together. specifications associated with axial flux difference, quadrant tilt, and control rod insertion limits provide limits on process variables that characterize and control the three dimensional power distribution of the reactor core. Control of these variables ensures that the core operates within the fuel design criteria and that the power distribution remains within the bounds used in the safety analyses.

The excore detectors are somewhat insensitive to disturbances near the core center or on the major axes. It is therefore possible that a five percent tilt might actually be present in the core when the excore detectors respond with a two percent indicated quadrant tilt. On the other hand, they are overly responsive to disturbances near the periphery on the 45 axes.

Tilt restrictions are not applicable during the stanup and initial testing of a reload core which may have an inherent tilt. During this time sufficient testing is performed at reduced power to verify that the hot channel factor limits are met and the nuclear channels are properly aligned.

The excore detectors are normally aligned indicating no quadrant power tilt because they are used to alarm on a rapidly developing tilt. Tilts which develop slowly are more accurately and readily discerned by incore measurements. The excore detectors serve as the prime indication of a quadrant power tilt. If a channel fails, is out-of-service for testing, or is unreliable, two hours is ,

a short time with respect to the probability of an unsafe quadrant power tilt developing. Two hours gives the operating personnel sufficient time to have the problem investigated and/or put into operation one of several possible alternative methods of determining tilt.

Physics Tests Excentions The primary purpose of the at-power and low power physics tests is to permit relaxations of existing specifications to allow performance ofinstrumentation calibration tests and special physics tests. The at-power specification allows selected control rods and shutdown rods to be 1 positions outside their specified alignment and insertion limits to conduct physics tested at l power. The power level is limited to 585 percent of rated thermal power and the power range i neutron flux trip setpoint is set at maximum of 90 percent of rated thermal power. Operation with thermal power $85 percent of rated thermal power during physics tests provides an l acceptable thermal margin when one or more of the applicable specifications is not being met. l The Power Range Neutron Flux - High trip setpoint is reduced so that a similar margin exists between the steady-state condition and the trip setpoint that exists during normal operation at rated thermal power.

The low power specification allows selected control and shutdown rods to be positioned outside of their specified alignment and insertion limits to conduct physics tests at low power. If power l exceeds two percent, as indicated by nuclear instrumentation. during the performance oflow i power physics tests, the only acceptable action is to open the reactor trip breakers to prevent operation of the reactor beyond its design limits. Immediately opening the reactor trip breakers will shut down the reactor and prevent operation of the reactor outside ofits design limits. If the Unit 1 - Amendment No. 15.3.10-17 Unit 2 - Amendment No.

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RCS lowest loop average temperature falls below the minimum temperature for criticality. the j temperature should be restored within 15 minutes because operation with the reactor critical and temperature below the minimum temperature for criticality could violate the assumptions for  ;

accidents analyzed in the safety analyses. If the temperature cannot be restored within 15  ;

minutes, the plant must be made subcritical within an additional 15 minutes. This action will '

place the plant in a safe condition in an orderly manner without challenging plant systems.

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j Unit 1 - Amendment No. 15.3.10-18 Unit 2 - Amendment No.

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TABLE 15.4.1-2 MINIMUM FREOUENCIES FOR EOUIPMENT AND SAMPLING TESTS Int Frea uene_v

1. Reactor Coolant Samples Gross Beta-gamma 5/ week

• activity (excluding tritium)

Tritium activity Monthly Radiochemical E Semiannually * )

l Determination l

l Isotopic Analysis for Every two weeks

• Dose Equivalent I-l'31 Concentration Isotopic Analysis for a.) Once per 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> Iodine including I-131, whenever the specific l-133, and I-135 activity exceeds 1.0 Ci/

gram Dose Equivalent 1-131 or 100/E Ci/ gram.* L b.) One sample between 2 and 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> following a thermal power change exceeding 15% of rated power in a one-hour period.

Chloride Concentration 5/ week

• Diss. Oxygen Conc. 5/ week

• Fluoride Conc. Weekly

2. Reactor Coolant Boron Boron Concentration Twice/ week j

3. Refueling Water Storage Boron Concentration Weekly

• Tank Water Sample 4 Boric Acid Tanks Bcron Concentration Twice/ week and after each BAST concentration change when they are being relied upon as a source of borated water.

1. Spray Additive Tank NaOH Concentration Monthly

6. Accumulator Boron Concentration Monthly Unit 1 - Amendment No.

l Unit 2 - Amendment No. Page1of5

, , ,, TABLE 15.4.1-2 (Continu:d) l T.s.g Freauenev

7. Spent Fuel Pit a) Boron Concentration Monthly b) Water Level i

Verification , Weekly

8. Secondary Coolant Gross Beta-gamma Weekly (  ;

Activity or gamma isotopic analysis lodine concentration Weekly when gross l Beta-gamma activity  !

equals or exceeds ,

1.2 Ci/cci i

9. Control Rods a) Rod drop times of all Each refueling or full length rods d' after maintenance that could affect i proper functioningH) j b) Rodworth measurement Following each refueling shutdown prior to commencing power operation

10. Control Rod Partial movement of Every 2 weeks 08) all rods l

11. Pressurizer Safety Valves Set point Every five years ("'

12. Main Steam Safety Valves Set Point Every five years ("I

13. Containment Isolation Trip Functioning Each refueling shutdown

14. Refueling System Interlocks Functioning Each refueling shutdown

15. Service Water System Functioning Each refueling shutdown

16. Primary System Leakage Evaluate Monthly (*)

17. Diesel Fuel Supply Fuel inventory Daily

18. Turbine Stop and Governor Functioning Annually (6)

Vaives

19. Low Pressure Turbine Visual and magnetic Every five years Rotor Inspection

• particle or liquid penetrant

20. Boric Acid System Storage Tank and Daily" p: ping temperatures 2: temperature required by Table 15.3.2-1 Unit 1 - Amendment No.

l l Unit 2 - Amendment No. Page 2 of 5 l

, , , , , , TABLE 15.4.1-2 (Continuid)

Igg Freauency

21. PORV Block Valves a. Complete Valve Cycle Quarterly UU

b. Open position check Every 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> (*

22. Integrity of Post Accident Evaluate Each refueling  !

Recovery Systems Outside cycle Containment i

23. Containment Purge Supply Verify valves are Monthly

• and Exhaust Isoir. tion locked closed Valves  !

24. Reactor Trip Breakers a. Verify independent Monthly

• operability of automatic shunt and '

undervoltage trip functions. t

b. Verify independent Each refueling operability of man- shutdown ual trip to shunt and undervoltage trip i functions. '

i

25. Reactor Trip Bypass a. Verify operability Prior to Breakers of the undervoltage breaker use ,

trip function.

l l

b. Verify operability Each refueling of the shunt trip shutdown functions.

c. Verify operability Each refueling of the manual trip shutdown to undervoltage trip functions.

26. 120 VAC Vital Instr. Verify Energizedo2) Shiftly Bus Power

27. Power Operated Relief OperateUO Each shutdown"U Valves (PORVs),

PORV Solenoid Air Control Valves, and Air System Check

28. Atmospheric Steam Dumps Complete valve cycle Quarterly

29. Crossover Steam Dump System Verify operability of Quarterly each steam dump valve.

Unit 1 - Amendment No.

l Unit 2 - Amendment No. Page 3 of 5

. . ..- - -- __-__. - - - - .- - .-. - - - . - - . ~ . -

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. , , . TABLE 15.4.1-2 (Continued)

30. Pressurizer Heaters Verify that 100 KW of Quarterly heaters are available. i

31. CVCS Chargingi mps Verify rability Quarterly j Pumps

32. Potential Dilution in Verify operability of Prior to placing plant in Progress Alarm alarm. cold shutdown. i 4

6 l 33. Core Power Distribution Perform power distribu. Monthly '2*

i tion maps using movable I incore detector system I to confirm hot channel factors.

i  ;

34. Shutdown Margin Perform shutdown margin Daily '2"  !

j calculation. i 1(1) Required only during periods of power operation.

{ (2) E determination will be staned when the gross activity analysis of a filtered sample indicates 210 Ci/cc and will be redetermined if the primary coolant gross radioactivity of a filtered sample l

increases by more than 10 Ci/cc.

1 (3) Drop test shall be conducted at rated reactor coolant flow. Rods shall be dropped under both cold and hot condition, but cold drop tests need not be timed.

l (4) Drop tests will be conducted in the hot condition for rods on which maintenance was performed.

(5) As accessible without disassembly of rotor.

(6) Not required during periods of refueling shutdown.

', (7) At least once per week during periods of refueling shutdown. I i- (8) . At least three times per week (with maximum time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> between samples) during periods of .

4 refueling shutdown.

j (9) Not required during periods of cold or refueling shutdown, but must be performed prior to exceeding 200*F if l it has not been performed during the previous surveillance period.

(10) Sample to be taken after a minimum of 2 EFPD and 20 days power operation since the reactor was last

, suberitical for 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or longer. j (11) An approximately equal number of valves shall be tested each refueling outage such that all valves will  ;

be tested within a five year period. If any valve fails its tests, an additional number of valves equal to the i e number originally tested shall be tested. If any of the additional tested valves fail, all remaining valves i {

shall be tested. ,

, (12) The specified buses shall be determined energized in the required manner at least once per shift by

! verifying correct static transfer switch alignment and indicated voltage on the buses.

(13) Not required if the block valve is shut to isolate a PORV that is inoperable for reasons other than excessive seat leakage.

(14) Only applicable when the overpressure mitigation system is in service.

(15) Required to be performed only if conditions will be established, as defined in Specification 15.3.15,

, where the PORVs are used for low temperature overpressure protection. The test must be performed

prior to establishing these conditions.

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Unit 1 - Amendment No.

l Unit 2 - Amendment No. Page 4 of 5

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l TABLE 15.4.1-2 (Continued)

(16) Test valve operation in accordance with the inservice test requirements of the ASME Boiler and Pressure Vessel Code,Section XI.

(17) Operability of charging pumps is verified by ensuring that the pumps develop the required flowrate, as specified by the In-Service Test Program.

(18) Not required to be performed if the reactor is subcritical.

(19) Required only when the BAST (s) are relied upon as a source of bort:ed water.

l (20) Perform during power operation at effective full power monthly intervals. Following a refueling i shutdow n, a power distribution map shall be performed prior to exceeding 90% of rated thermal power.

(21) Only applicable during low-power physics testing.

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b Unit 1 - Amendment No.

l Unit 2 - Amendment No. Page 5 of 5