ML20009D105

Proposed Tech Specs Upgrading Provisions Re Operation W/ Tripped or Bypassed Reactor Protection or Emergency Safeguards Feature Channel

ML20009D105
Person / Time
Site:	Fort Calhoun
Issue date:	07/22/1981
From:	OMAHA PUBLIC POWER DISTRICT
To:
Shared Package
ML20009D100	List: ML20009D099 ML20009D102 ML20009D105
References
TAC-7089, NUDOCS 8107230151
Download: ML20009D105 (9)

Text

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. LIMITING CONDITIONS FOR OPERATION 2.15 Instrumentatio. and Control Systems l

Applicability Applies to plant instrumentation systems.

Objective-To delineate thegonditions 'of the plant instrumentation and

control' systems necessary to assure reactor safety.

Specifications The-operability of the plant instrument and control syste=s shall

.be in accordance with Tables 2-2 through 2-6.

~

In the event the number of channels of' a particular system in

. service falls one below the total number of four channels, the inoperable channel shall be pla.:ed in either the bypassed or tripped condition within eight leurs.

For the purpose of testing and maintenance, the inoperable channel may be bypassed for up to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> from time of initial. less of operability; however, if -

the inoperability is determined as the result of malfunctioning RTD's or nuclear detectors supplying signals to the high power level, thermal margin / low pressurizer pressure, axial power distribution, and high rate trip-vida log trip units, these

- channels may be bypassed for up to T days from time of initial loss of operability..If the inoperable channel is not restored to operable status after the allowable times for bypass, it shall be placed-in the tripped position.

If required for active mainte-nance and surveillance testing to establish operability and place a channel back in service, the trip unit may be installed and by-

. passed after the 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or 7 day period, whichever is appli-cable.

In the event the number of channels of a particular system in service falls to the limits given in the column entitled " Minimum Operable Channels", one of the inoperable channels must be placed in the tripped position at the time of initial loss of oper-ability. The second inoperable channel, for purposes of testing and' maintenance, may be bypassed for up to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.

If the channel has not been restored to operable status after h8 hours, the reactor'shall be placed in a hot shutdown condition within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />; however, operation can continue without containment iso-lation_ signals available if the ventilation isolation valves are closed. If after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> from time of initiating a hot shutdown procedure the inoperable channel has not been restored to oper-able status, the reactor shall be placed in a cold shutdown condition vithin 2h hours.

~ Amendment No. $, 20, 54 2-65 ATTACIMENT A 8107230151 810722 l PDR ADOCK 05000205 rs

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2.0 LIMITIUG CONDITIONS FOR OPERATION 2.15 Instrumentation and Control Systems (Continued) in the event the number of channels of a particular system in service falls below the limits given in the columns entitled

" Minimum Operable Channels" or " Minimum Degree of Redundancy",

except as conditioned by the column entitled " Permissible Bypass Conditions", -the reactor shall be placed in a hot shutdown con-dition within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />; however, operation can continue without containment isolation signals available if the ventilation iso-lation valves are closed.

If minimum conditions are not met within 2h hours, the reactor shall be plcced in a cold shutdown condition within 2h hours.

If, during power operation, the rod block function of the second-ary CEA position indicatien system and rod block circuit are inoperable for more than 2h hours, or the plant computer PDIL alarm, CEA group deviation alarm and the CEA sequencing function are inoperable for more than h8 hours, the CEA's shall be with-drawn and maintained at fully withdrawn and the control rod drive system mode switch shall be maintained in the off position except when manual motion of CEA Group 4 is required to control axial power distribution.

Basis During plant operation, the complete instrumentation systems will normally be in service. Reactor safety is provided by the re-actor protection system, which automatically initiates appro-priate acticn to prevent exceeding established limits. Safety is not compromised, however, by continuing operation with certain instrumentation channels out of service since provisions were made for this in the plant design. This specification outlines limiting conditions for operation necessary to preserve the effectiveness of the reactor control and protection system when any one or more of the channels are out of service.

All reactor protection and almost all engineered safety feature channels are supplied with sufficient redundancy to provide the capability for channel test at power, except for backup channels such as derived circuits in engineered safeguards control system.

When one of the four channels is taken out of service for mainta-nance, the protective system logic can be changed to a two-out-of-three coincidence for a reactor trip by bypassing the removed channel.

If the bypass is not effected, the out-of-service channel (Power Removed) 2-65a

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TABLE'2-2 i

" Instrument Operating Requirements-for Reactor Protective System Test,-

Minimum Minimum.

Permissible.

Maintenance Operable

.De' gree of

- Bypass

.& Inoperable L No.-

Functional Unit Channels Redundancy Condition Bypass -

11 Manual (Trip Buttons) 1..

None'

- None N/A

-1(C)-

Thermal Power Input.(e)(f) 2

~High-Power /Avel

-2(b)(c)

Bypa,ssed Below 4% of Rated-

- Power (a)(d) 3'

Ther=al Margin /Lov a2(D)'

1

- Below 10-45 (e)(f)

Pressurizer Pressure-Eated Power (

(d) s y

dL High Pressurizer.

2(b) 1 None (e)

. Pressure.

s

-5 Low R.C. Flow 2(b).

1 Below:10 A%

(e)

Rated Power (oa (d)

'6.

= Low Steam Generator-2/s e 1/ Steam None

-(e)

Gen {DpL Water Level Gen 7

Low Steam Generator..

2/Stegn.

1/ Steam

. Below 550 psia (e)

Pressure Gen (b).

Gen (a)(d) 8-lContainment High 2(b)

- 1' During Leak Test (e)'

Pressure Axial Power Dis-2(b)(c) 1(c)-

Belov 15% of Rated '(e)(f) 9l

_'tribution Power i

"10~

High Rate Trip.

2 1

Below 10-N% and (e)(f)

Wide Range Log.

Above15%o{a)

Channels Rated Power

_11 Loss' of Load 2(b) 1 Below 15% of Rated (e)

Power Ea'

Bypass automatically removed.

b

One' of the inoperable channels must be in the tripped condition at time of initial loss of operability. - If second channel is inoperable after h8 hours a unit shutdcvn must be initiated.

e' If two channels are -inoperable, load shall be reduced to 70% or less of rated power.

d-For low pcwer physics testing this trip may be bypassed up to 10-15 of rated

, power.

e' Channel may be in bypass for up to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> from time of initial loss of

~ operability.

I 2-67 Change No. 7 February 28, 1974 m

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. TABLE 2 '

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- If inoperable channel determined to be: caused by malfunctioning RTD's or

.nuc ear. detectors the channel.may be bypassed for up to 7' days from time l

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1 of initial loss of ' operability.

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TABLE 2-3 Instrument Operating Requ'irements' for Engineered Safety Features

Test, Minimum. : Minimum

. Permissible Maintenance '

'No.

• Functional Unit _

Operable. Degree of Bypass

& Inoperability s

Channels Redundancy Conditions Bypass

/

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Safety Injection

[A Manuali

1

'None' None N/A

B High Containment.

Pressure'A-2(")(d)

,1-During Leak Test (f)'

B.

-2(a)(d)

' C '-

' Pressurizer Low /'

Low Pressure A 2(a)(d)-- ~

Reactor Coolant (f)

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B'

-2(a)(d):

1 Pressure Less Than 1700 psia (b)

2' Containment Spray-t.-

A JManual.

1 Hone:

None N/A IB-High Containmenti sPressure'A.

2(a)(c)(d) 1 During Leak Test (f)

B 2(a)(c)(d) 1 C.

~ Pressurizer Low /

Low A 2(a)(c)(d) 1 Reactor Coolant (f)

B-2(a)(c)(d) 1 Pressure Less Than 1700 psia (b)

~

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'3:

-Recirculation

-As.

Manual-1 Hone None N/A SB-SIRW Tank. Low Level'A 2(a)(d) 1 None-(f)

B 2(a)(d) 1 I mergeney Off-Site Power Trip

~~h E

Al

~. Manual' 1(e)

None None (f)

'B-

. Emergency Bus. Low Voltage (Each Bus)

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2((d) 1 Reactor Coolant (f)

Loss of Voltage 2 a)(d) 1 Temperature Less

--Degraded Voltage Than 300 F r a' -

A'and B actuation circuits each have 4 channels.

b Auto removal. of bypass. above 1700 psia.

7 c

Coincident high containment pressure and pressurizer low / low pressure signals required for initiation of containment spray.

Amendment No. 41 2-68

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One of th'e inoperable, channels must-be in the tripped condition'at time

- of. initial: loss of operability.

If.second channel is inoperable after

.kB hours.a unit' shutdown must be initiated.

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.e Control. switch on incoming breaker..

' f.

' Channel may be' bypassed for.up to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> from time of initial loss of operability.

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4 DISCUSSION A revis w of the four channel RPS and ESFAS for four channel in-dependence was requested by the NRC to determine if long term operation of a 2-out-of-3 logic configuration is acceptable.

The investigation was to determine independence based on both physical and electrical separation. ~If the review revealed that sufficient channel independence did-not exist, a change to the Technical Specifications (TS) should be initiated.

As a result of the review at the Fort Calhoun Station, the proposed change-to the TS is being submitted. The proposed TS change would allow for a channel to be bypassed for up to h8 hours for the purposes of

- testing and maintenance.

If the inoperable channel is due to malfunc-tioning of the hot and cold leg RTD's or nuclear detectors, the channel may be bypassed for up to.7 days from time of initial loss of oper-ability.

The Fort Calhoun Station RPS and ESFAS are composed of four channels.

These channels are povered from a two battery-two bus system with each channel having a separate AC power inverter.

The RPS cabinets in the main control room panels are separated by partitions for fire protection; however, the panel allows for an associated circuit to be routed with another protective channel. Cabling from the panels is routed with maintained separation by trays through the cable spreading room initially and then through separate trays or conduit to the destinatie+. site.

Within containment, a possibility exists that a high energy line break could disable two redundant safety-related transmitters; however, out-side of containment the cables are not routed near high energy lines.

The TS changes are broken into the h8-hour and 7-day bypass cate-gories. These we'e chosen because of the following:

1.

Bypassing of a channel for up to kB hours for the purpose of testing and maintenance has been approved for other four channel CE systems because they exhibit some independence.

Since the Fort Calhoun Station is a four channel CE system similar to the other units, the h8-hour bypass should be justified by precedent.

2.

The T-day bypass is for the channels with inputs from the RTD's in the main coolant piping and the nuclear detectors. A review of each revealed the following:

a.

The RTD's in the main coolant piping could only be lost in the unlikely event of the main coolant line breaking.

There are no other high energy lines located near the main coolant piping.

b.

The nuclear detectors are housed in receptacles imbedded in concrete housing the core with maximum separation being maintained as shown in the FSAR Figure 7 5-1.

The cables from the detectors are separately routed from each other, including separation at the containment pene-tration areas.

ATTACHMENT B

With these elements being located in unaccessible areas

. during operation, the 7-day bypass vould allow for thorough

- coordination and preparation fs-

, heir repair or replacement.

Because of the previous demot sted relisbility of the DC I

batteries, a failure of the batteries during this 7 day period would be highly unlikely. Therefore, it is the opinion of the District that because of the increased separation and high reliability of these parameters, there would be no increased probability Cf accident during this 7 day period.

Due to the hardware installation, 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> is allowed to place channels into the tripped condition. Since some channels do not have bypass keys and bypass or trip of those channels must be ' effected by viring changes, 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> is alJoved fcr safe bypassing or tripping of the channels.

Provision is made to place a trip unit in bypass for active maintenance or surveillance testing after the h8 hours or 7 days has expired to prove operability.

Hardware restrictions require channels to be bypassed to energize test functions.

The proposed change does not constitute an unreviewed safety question. Since there are no equipment or setpoint changes being 4

implemented by the proposed license changes, there is:

1.

No probability of increased' occurrence or consequences of an accident or malfunction of equipment important to safety previously evaluated.

2.

No possibility of an accident or malfunction of a different type than any evaluated previously in the safety analysis report being created.

3.

No reduction in the margin of cafety as defined in the basis for any Technical Specifications.

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FEE JUSTIFICATION a

~

The proposed amendment is deemed to be Class.III, within the meaning of 10 CFR 170.22.

It addresses-a single safety issue and does-

- not involve a significant. hazard. consideration.

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1 ATTACHttENT C