ML20247G012

Proposed Tech Spec Pages 19,99,100,101,102,102a,107,108 & 109,removing Rod Sequence Control Sys & Reducing Rod Worth Minimizer Low Power Setpoint

ML20247G012
Person / Time
Site:	Peach Bottom
Issue date:	07/19/1989
From:	PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:
Shared Package
ML20247F993	List: ML20247F992 ML20247G012
References
NUDOCS 8907270303
Download: ML20247G012 (15)

Text

,- _

.I

\\

.i !

Docket Nos. 50-277 7 ;. 278

-'~

License Nos.'DPR-44 DPR-56 ATTACHMENT 2 PEACH. BOTTOM ATOMIC POWER STATION UNITS 2 AND 3 y

Docket Nos. 50-277 50-278

.l i

License Nos. DPR-44 DPR-56 TECHNICAL SPECIFICATION CHANGES 1

List of Attached Pages 19 99 (Unit 2, Unit 3) 100 101 (Unit 2, Unit 3) 102 (Unit 2, Unit 3) 102a (Unit 2, Unit 3) 107 108 109 (Unit 2, Unit 3) 8907270303 890719 PDR ADOCK 05000277 p.

PDC

Units 2 and 3 PBAPS 2.1.A BASES (Cont'd.)

An increase in the APRM scram trip setting would decrease the margin present before the fuel cladding integrity Safety Limit is reached.

The APRM scram trip setting was determined by an analysis of margins required to provide a reasonable range for maneuvering during operation.

Reducing this operating margin would increase the frequency of spurious scrams which have an adverse effect on reactor safety because of the resulting thermal stresses.

Thus, the APRM scram trip setting was selected because it provides adequate margin for the fuel cladding integrity Safety Limit yet allows operating margin that reduces the possibility of unnecessary scrams.

The scram trip setting must be adjusted to assure that the LHGR transient peak is not increased for any combination of maximum fraction of limiting power density (MFLPD) and reactor core thermal power.

The scram setting is adjusted in accordance with the formula in Specification 2.1.A.1, when the MFLPD is greater than the fraction of rated power (FRP).

Analyses of the limiting transients show that no scram adjustment is required to assure MCPR greater than the fuel cladding integrity safety limit when the transient is initiated from MCPR greater than the operating limit given in Specification 3.5.K.

For operation in the startup mode while the reactor is at low pressure, the APRM scram setting of 15 percent of rated power provides adequate thermal margin between the setpoint and the Safety Limit, 25 percent of rated.

The margin is adequate to accommodate anticipated maneuvers associated with power plant startup.

Effects of increasing pressure at zero or low void content are minor, cold water from sources available during startup is not much colder than that already in the system, temperature coefficients are small, and control rod patterns are constrained to be uniform by operating procedures backed up by the Rod Worth Minimizer.

Worth of individual rods is very low l

in a uniform rod pattern.

Thus, of all possible sources of reactivity input, uniform control rod withdrawal is the most probable cause of

.significant power rise.

Because the flux distribution associated with uniform rod withdrawals does not involve high local peaks, and because byasignificantpercentagel several rods must be moved to change power is very slow.

Generally, of rated power, the rate of change of power the heat flux ir in near equilibrium with the fission rate.

In an assumed uniform rod withdrawal approach to the scram level, the rate of power rise is no more than 5 percent of rated power per minute, and the APRM system would be more than adequate to assure a scram before the power could exceed the Safety Limit.

The 15 percent APRM scram remains activa until the mode switch is placed in the RUN position.

This switch occurs when the reactor pressure is greater than 850 psig..

l f

}

I

~ Unit 2 l

+

j f

n1 PBAPS

]

LIMITING CONDITIONS FOR OPERATION

' SURVEILLANCE REQUIREMENTS

]

1

'3.3f REACTIVITY CONTROL 4.3 REACTIVITY CONTROL

~

Applicability:

Applicability:

Applies to the operational status.

Applies to the surveillance requiremmts of..the control rod system.

of the control rod system.

Objective:

Objective:

To assure the' ability of the control To verify the ability.of the control-

[

rod system to control reactivity, rod system to control reactivity.

Specification:

Specification:

lA.

Reactivity Limitations A. Reactivity Limitations t

l

-1.

Reactivity margin - core loading

1. Reactivity margin - core loading A sufficient number of control rods Sufficient control rods shall-

-shall be-operable so that the core be withdrawn following a refueling outage j

could be made subcritical.in the most when core alterations were performed to reactive condition during the demonstrate with a margin of 0.38%W K/X operating: cycle with the strongest that the core can be made subcritical at control rod fully withdrawn and any time in the subsequent fuel ~ cycle all other operable control rods with the analytically determined fully inserted.

strongest operable control rod fully withdrawn and all other operable rods fully inserted.

2.

Reactivity margin - inoperable control

2. Reactivity margin'- inoperable control rods rods

a. Control rods which cannot be moved

a. Each partially or fully withdrawn with control rod. drive pressure operable control rod shall be exercised shall be considered inoperable.

one notch at least once each week when operating above the RWM low power l

setpoint. Each partially or fully If a partially or fully withdrawn withdrawn operable control rod shall control rod drive cannot be moved be exercised at least one notch with drive or scram pressure the at least every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when reactor shall be brought to a operating above the RWM. low power shutdown condition within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> setpoint if there are three unless investigation demon-or more inoperable control l

strates that the cause of the rods or when operating above H

the RWM low power setpoint l

if there is one fully 1

l l

1 i

\\7

[.

/

]

v 37

' Unit 3 ch,..

je'~

PBAPS

'1 LLIMITING CONDIT10ES FOR OPERATION SURVEILLANCE REQUIREMENTS

,T3.3 ' REACTIVITY CONTROL.

4.3 REACTIVITY CONTROL Applicability:-

Applicability:

~'

. Applies to tiie operational status Applies to the surveillance requirements of the~ control rod system.

of the control rod system.

Objective:

Objective:

.To assure the ability of the control To verify t'he ability of the control

.p rod system to control. reactivity..

-rod system to control reactivity.

Specification:

Specification:

i

.A.

' Reactivity Limitations A. Reactivity Limitations 1.

-Reactivity margin - core loading

1. Reactivity margins - core loading A sufficient number of control rods

~ Sufficient control rods shall shall-be operable so that the core be withdrawn following a refueling outage-could'be made subcritical in the most when core alterations were performed to reactive' condition during the demonstrate with a margin of 0.38%W K/K operating _ cycle with the strongest that the core can be made subcritical at control rod fully withdrawn and any time in the subsequent fuel cycle all other operable control-rods with the analytically determined.

fully inserted.

strongest operable control rod fully withdrawn and all other.

operable rods fully inserted.-

2.

Reactivity margin - inoperable control

2. Reactivity margin - inoperable control rods rods

a. Control rods which cannot be moved

a. Each partially or fully withdrawn with control rod drive pressure operable control rod shall be exercised shall be considered inoperable.

one notch at least once each week when operating above the RWM low power i

setpoint. Each partially or fully l

If a partially or fully withdrawn withdrawn operable control rod shall control rod drive cannot be moved be exercised at least one notch with drive or scram pressure the at least every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when reactor.shall be brought to a operating above the RWM low power shutdown condition within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> setpoint if there are three unless investigation demon-or more inoperable control I

strates that the cause of the rods.or when operating above the RWM low power setpoint if there is one fully 1 1 go2

W

,_PBAPS'

. Units 2cand:3: {

3; gy*

t:

n' 1

p LIMITINGCCONDITIONS FOR' OPERATION-SURVEILLANCE' REQUIREMENTS

)

1 l>

23.3.AiReactivity Limitations 4.3.A:

Reactivity Limitations iI

.(Cont'd.).

(Cont'd.)

1 I

failure is not.due to a or part'ially; withdrawn rod failed' control' rod drive which cannot be moved and for mechanism. collet ~ housing.

which control rod drive' mech-a anism damage has not been ruled out.

.The. surveillance need~not be completed within.24Lhours if-the number'of inoperable rods-has been reduced to less than 3:d and if it has been demonstrated-

-that control rod drive mech-

.J anism collet, housing failure isj!

not the cause of an immovable-

-j control rod.

b'.

'The' control rod directional b.

'The scram discharge volume control valves for.inoper-drain and vent: valves shall able control rods shall be verified-open at least

^

disarmed electrically and

.once per month.

These valves the control rods shall be may be closed intermittently

in such positions that for testing.

Specification 3.3.A.1 is met.

c.:

Control rods with scram times c.

At least once every 3 greater-than those permitted months verify that:the by Specification 3.3.C.3 are scram discharge volume 4

inoperable ~ ~

if they can drain.and vent valves:

but be inserted with control rod closed wi'th 15 seconds drive pressure they need not after receipt of a closure be disarmed electrically.

signal, and reopen upon reset of the closure signal.

d..

DELETED d.-

DELETED e.

Control rods with inoperable accumulators or those whose position cannot be positively determined shall be 1

considered inoperable.

1 J

1

- (

-100-1 a

l

w

, [f Y

.c e

PBAPS

~.

LIMITING. CONDITIONS FOR OPERATION' SURVEILLANCE REQUIREMENTS i

93.3.A Reactivity' Limitations 4.3.A Reactivity Limitations

'(Cont'd)

(Cont'd) f.

' Inoperable. control rods shall be>

-positioned.such that specification

3.3. A. l ' is = met.

In addition, during reactor power operation, no more than L

one' control rod in any 5 x 5 array:

l' may,be inoperable'(at le'ast 4

~

operable! control rods must separate any.2 inoperable.ones)~.

If this

. Specification cannot be met the reactor'shall not be started, or if at power, the reactor shall be brought to a cold shutdown condition ~within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

B.

' Control Rods B..

Control Rods 1.

,Each control rod shall be

-1.

The coupling integrity shall

. coupled to its drive or.

be verified for each withdrawn 1

completely. inserted and the control rod as follows:

control rod directional.

control valves disanned '

a. When a rod is withdrawn electrically.- This requirement the first time after each does not apply in the..

refueling outage or after i

refuel condition when the maintenance, observe discernible

-I.

reactor:is vented. Two control response of the nuclear rod drives may be removed instrumentation and rod as long as Specification 3.3.A.1 position indication for

.is met.

the " full-in"'and " full-out" position.

However, for initial.

rods when response is not l

discernible,' subsequent exercising of these rods after the reactor is above the Rod Worth Minimi7er-low power setpoint shall be performed to verify instrumentation response,

b. When the rod is fully withdrawn the first time after each refueling outage or after maintenance observe I

that the drive does not go to the overtravel position.

-101-

Unit'3 PBAPS l

1 LIMITING CONDITIONS'FOR OPERATION SURVEILLANCE REQUIREMENTS i

3.3.A Reactivity Limitations 4.3.A Reactivity Limitations (Cont'd)

(Cont'd) j 1

.f.

, Inoperable control rods shall be j

. positioned such'that specification

'3.3.A.1 is' met.

In addition, during reactor power operation, no more than one control rod'in any 5 x 5 array may be inoperable (at least 4 operable control rods must separate any 2 inoperable ones).

If this-

.i Specification cannot be met the l

reactor shall not be started, or if at power, the reactor shall be brought to a cold shutdown condition within 24' hours.

q 1

B.

Control Rods B.

Control Rods

1.

Each control rod shall be 1.

The coupling integrity shall j

coupled.to its drive or be verified for each withdrawn completely inserted and the control rod as follows:

control rod directional control valves disarmed

a. When a rod is withdrawn.

electrically. This requirement the first time after each does not apply in the refueling outage or after refuel condition when the maintenance, observe discernible l

reactor is vented. Two control response of the nuclear rod drives may be removed instrumentation and rod as long as Specification 3.3.A.1 position indication for is met.

the " full-in" and " full-out" position.

However, for initial rods when response is not discernible, subsequent l

exercising of these rods after 1

the reactor is above the Rod Worth Minimizer low power setpoint shall be performed to verify instrumentation response.

1 e

b. When the rod is fully withdrawn the first time after each refueling outage or after maintenance observe that the drive does not go to the overtravel position, j

-101-

PBAPS Unit 2 4

9

• LIM [ TING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS l

3.3.B Control Rods (Cont'd.)

4.3.B Control Rods (Cont'd.)

l c.

During each refueling outage'i and after control rod l

maintenance, observe that the drive does not go to the overtravel position.

l l

~ 2.

The"c'ontrol rod drive' housing 2.

The control rod drive housing I

support system shall be in support system shall be in-place during reactor power spected after reassembly and operation or when the reactor the results of the Inspection coolant system is pressurized recorded.

above atmospheric pressure with fuel in the reactor vessel, unless all control rods are fully inserted and Specification 3.3.A.1 is met.

3.a.

DELETED 3.a. DELETED i

l

-102-

crn;L.

1_.-------

PBAPS

.. s.

Unit 3' j

LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS i

i 3.3.B Control-Rods (Cont'd.)

4.3.B Control Rods (Cont'd.)

c.

During each refueling outage and after control rod maintenance, observe that the drive does not go to the overtravel position.

~ 2 '. 'The control rod d' rive hous'ing 2.

The control rod drive housing

~

support system shall be in support system shall be in-place during reactor power spected after reassembly and operation or when the reactor the results of the Inspection coolant system is pressurized recorded.

I above atmospheric pressure with fuel in the reactor vessel, unless all control l

rods are fully inserted and Specification 3.3.A.1 is met.

3.a.

DELETED 3.a.

DELETED

')

i

-102-i i

Unit 2 i

PBAPS l

7 LIMkTINGCONDITIONSFOROPERATION SURVEILLANCE REQUIREMENTS

3.3.B-Control Rods (Cont'd) 4.3.B Control Rods (Cont'd) b..

The Rod Worth Minimizer.

b.1.

Prior to the start of control rod (RWM)lowpowersetpointis withdrawal towards criticality greater than or equal to 10%

and prior to attaining the Rod of rated power. Whenever the reactor Worth Minimizer low power set-

)

is in the startup or run modes with point during rod insertion

{

thermal power less than or equal at shutdown, the Rod Worth Minimizer to the Rod Worth Minimizer (RWM)

(RWM) shall be demonstrated to be j

low power setpoint the Rod Worth.

operable by the following Minimizer shall be operable except-checks:

as follows:

a. The RWM computer on line 1.

With the RWM inoperable after diagnostic test shall be the first 12 control rods are fully successfully performed.

withdrawn, operation may continue provided that control rod movement

b. Prior to the start of control and compliance with the prescribed rod withdrawal only, proper control rod pattern are verified annunciation of the by a second licensed operator or selection error of at least technically qualified member of the one out-of-sequence control station technical staff, rod in a fully inserted group shall be verified.

2.

With the RWM inoperable before the first 12 control rods are fully c.

The rod block function of the withdrawn, one startup per calendar RWM shall be verified by year may be perfomed provided that withdrawing the first rod control rod movement and compliance during start-up only as an with the prescribed control rod out-of-sequence control rod pattern are verified by a second no more than to the block point.

licensed operator or technically qualified member of the station 2.

Following any loading of the technical staff.

rod worth minimizer sequence program into the computer, the

3.. Otherwise, with the RWM inoperable, correctness of the control rod control rod withdrawal movement withdrawal sequence input to the l

shall not be permitted except by RWM computer shall be verified.

full scram. Control rods may be moved, under administrative c.

When required, the presence of the control to permit testing second licensed operator or associated with demonstrating technically qualified member operabity of the RWM.

of the station technical staff to verify the following of the correct rod program shall be verified and recorded.

c. DELETED

-102a-i l

n p

a:

Unit 3 i

PBAPS

^

. LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS

'3.3.B. Control' Rods (Cont'd) 4.3.B Control Rods (Cont'd)'

b.

The Rod Worth Minimizer b.1.

Prior to the start of control rod

'(RWM). low power setpoint is-withdrawal towards criticality greater than or equal to 10%

and prior to attaining the Rod-of rated power. Whenever the reactor Worth Minimizer low power set-is in the startup or run modes with point during rod insertion thermal power less than or equal at shutdown, the Rod Worth Minimizer to the Rod Worth Minimizer (RWM)

.(RWM) shall be demonstrated to be low power setpoint the Rod Worth operable by the following Minimizer.shall be operable except checks:

as follows:

a. The RWM computer on line 1.

With the RWM inoperable after diagnostic test shall be the first 12 control rods are fully successfully performed.

withdrawn, operation may continue provided that control rod movement

b. Prior to the start of control and compliance with the_ prescribed rod withdrawal only, proper control rod pattern are verified annunciation of the by a second licensed operator or selection error of at least technically qualified member of the one.out-of-sequence control station technical staff.

rod in a fully inserted group shall be verified.

. ith the RWM inoperable before W

.2.

.the first 12 control rods are fully c.

The rod block function of the withdrawn, one startup per calendar RWM shall be verified by year may be perfomed provided that withdrawing the first rod control rod movement and compliance during start-up only as an with the prescribed control rod out-of-sequence control rod pattern are verified by.a second no more than to the block point.

licensed operator or technically qualified member of the station 2.

Following any loading of the technical staff.

rod worth minimizer sequence program into the computer, the 3.

Otherwise, with the RWM inoperable, correctness of the control rod control rod withdrawal movement withdrawal sequence input to the q

shall not be permitted except by RWM computer shall be verified.

l full scram. Control rods may be moved, under administrative

'c.

When required, the presence of the control to pemit testing second licensed operator or associated with demonstrating technically qualified member l

operabity of the RWM.

of the station technical staff to verify the following of the correct rod program shall be verified o

l' and recorded.

L

c. DELETED L

i

-102a-f

n 4

Unit 2 and 3 3.3.A and 4.3.A BASES (Cont'd)

Studies have been made which compare experimental criticals with calculated criticals. ~ These studies'have shown that actual criticals can be predicted within a given tolerance band. For gadolinia cores that additional margin required due to control cell material manufacturing tolerances and calculational uncertainties has experimentally been determined to be 0.38%Ak/k. When this additional margin is demonstrated, it assures that the reactivity control requirement is met.

2.

Reactivity Margin - Inoperable Control Rods Specification 3.3.A.2 requires that a rod be taken out of service if it cannot be moved with drive pressure.

If the rod is fully inserted and then disarmed electrically *, it is in a safe postion of maximum contribution to shut down reactivity.

If it is disarmed electrically in a non-fully inserted postion, that position shall be consistent with the shutdown reactivity limitation. stated in Specification 3.3.A.1.

This assures that the core can be shutdown at all times with the remaining control rods assuming the strongest operable control rod does not insert.

Inoperable bypassed rods will be limited within any group to not more than one control rod of a (5x5) twenty-five control rod array. Also if damage within the l

control rod drive mechanism and in particular, cracks in drive internal housings, I

cannot be ruled out, then a generic problem affecting a number of drives cannot be ruled out. Circumferential cracks resulting from stress assisted intergranular corrosion have occurred in the collet housing of drives at several BWRs. This type of cracking could occur in a number of drives and if the cracks propagated until severence of the collet housing occurred, scram could be prevented in the affected rods.. Limiting the period of operation with a potentially severed rod and requiring increased surveillance after detecting one stuck rod will assure that.the reactor will not be operated with a large number of rods with failed collet housings.

• To disarm the drive electrically, four Amphenol type plug connectors are removed from the drive insert and withdrawal solenoids rendering the rod incapable of withdrawal. This procedure is equivalent to valving out the drive and is preferred because, in this condition, drive water cools and minimizes crud accumulation in the drive. Electrical disarming does not eliminate position indication.

{

i 1

1 l

l

-107-

PBAPS Unit 2 and 3 3.3 and 4.3 BASES (Cont'd)

B.

Control Rods 1.

Control. rod dropout accidents as discussed in the FSAR can lead to significant core damage.

If coupling integrity is maintained, the possibility of a rod dropout accident is eliminated. The overtravel position feature provides a positive check as only uncoupled drives may reach this position.

Neutron instrumentation response to rod movement provides a verification that the rod is following its drive. Absence of such response to drive movement could indicate an uncoupled condition.

Rod position indication is required for proper function of the rod worth minimizer (RWM).

l 2.

The control rod housing support restricts the outward movement of a control rod to less than 3 inches.in the extremely remote event of a housing failure. The I

amount of reactivity which could be added by this small amount of rod withdrawal, which is less than a normal single withdrawal increment, will not 4

contribute to any damage to the primary coolant system. The design basis is given in subsection 3.5.2 of the FSAR and the safety evaluation is given in subsection 3.5.4.

This support is not required if the reactor coolant system is at atmospheric pressure since there would then be no driving force to rapidly eject a drive housing. Additionally, the support is not required if all control rods are fully inserted and if an adequate shutdown margin with one control rod withdrawn has been demonstrated, since the reactor would remain subcritical even in the event of complete ejection of the strongest control rod.

3.

The Rod Worth Minimizer (RW4) restricts withdrawals and insertions of control o

rods to prespecified sequences. All patterns associated with these restrictions have the characteristic that, assuming the worst single deviation from the 1

restrictions, the drop of any control rod from the fully inserted position to the position of the control rod drive would not cause the reactor to sustain a power excursion resulting in the peak enthalpy of any pellet exceeding 280 calories per gram. An enthalpy of 280 calories per gram is well below the level at which rapid fuel dispersal could occur (i.e., 425 calories per gram).

Primary system damage in this accident is not possible unless a significant amount of fuel is rapidly dispersed.

Ref. Sections 3.6.6., 14.6.2 and 7.16.3.3 of the FSAR, NEDO-10527 and supplements thereto, and HEDE 24011-P-A.

O e

-108-

_____ ___ _ Q

'~

r v y., -

Unit 3

^ '

PBAPS k

l 3.3.B and 4.3.B BASES (Cont'd)

In perfortning the function described above, the RWM is not needed to impose any restrictions at core power levels in excess of 10 percent of rated power.

Material in the cited references shows that it is impossible to reach 280 calories per gram in-the event of a control rod drop occurring at a power level greater than.10 percent, l

regardless of the rod pattern.- This is true for all nortnal and abnormal patterns, including those which maximize individual control rod worthi.

The Rod Worth Minimizer provides automatic supervision to assure that out-of-sequence control rods will not be withdrawn or inserted, i.e., the RWM system limits operator deviations from planned control rod movement. The RWM is an important system for minimizing the consequences of an RDA below 10% power. The RWM is therefore required to be operable for all but one startup per year before the first twelve control rods are fully withdrawn. One startup per year before the first twelve control rods are fully withdrawn will be permitted with the RWM inoperable provided control rod I

movement and compliance with the prescribed control rod pattern are verified by a second licensed operator or technically qualified member of the station technical staff. The function of the RWM makes it unnecessary to specify a license limit on rod worth to preclude unacceptable consequences in the event of a control rod drop.

At power levels below 10 percent of rated, the RWM forces adherence to acceptable rod patterns. Above 10 percent of rated power, no constraint on rod pattern is required to assure that rod drop accident consequences are acceptable. Control rod pattern constraints above 10 percent of rated power are imposed by power distribution

.l requirements as defined in Section 3.5/4.5 of the Technical Specifications.

4.

The Source Range Monitor (SRM) system performs no automatic safety system function; i.e., it has no scram function.

It does provide the operator with a visual indication of neutron level. The consequences of reactivity accidents are functions of the initial neutron flux.

1 i

1

-109-l l

7

,t PBAPS

.o 3.3.B and 4.3.B BASES (Cont'd)

In performing the function described above, the RWM is not needed to impose any restrictions at core power levels in excess of 10 percent of rated power. Material in the cited references shows that it is impossible to reach 280 calories per gram in -

the event of a control rod drop occurring at a power level greater than 10 percent.

l regardless of the rod pattern. This is true for all normal and abnormal patterns, including those which maximize individual control rod worth.

The Rod Worth Minimizer provides automatic supervision to assure that out-of-sequence control rods will not be withdrawn or inserted, i.e., the RWM system limits operator deviations from planned control rod movement. The RWM is an important system for minimizing the consequences of an RDA below 10f power. The RWM is therefore required to be operable for all but one startup per year before the first twelve control rods are fully withdrawn. One startup per year before the first twelve control rods are fully withdrawn will be permitted with the RWM inoperable provided control rod movement and compliance with the prescribed control rod pattern are verified by a second licensed operator or technically qualified member of the station technical staff.

Thp function of the RWM makes it unnecessary to specify a license limit on

{

rod worth to preclude unacceptable consequences in the event of a control rod drop.

At power levels below 10 percent of rated, the RWM forces adherence to acceptable rod patterns. Above 10 percent of rated power, no constraint on rod pattern is required to assure that rod d op accident consequences are acceptable.

Control rod pattern constraints above 10 percent of rated power are imposed by power distribution requirements as defined,in Section 3.5/4.5 of the Technical Specifications.

4.

The Source Range Monitor (SRM) system performs no automatic safety system function; i.e., it has no scram function.

It does provide the operator with a visual indication of neutron level. The consequences of reactivity accidents are functions of the initial neutron flux.

I

-109-