ML19327C186

Proposed Tech Specs Revising Section 2.7 Re Electrical Sys

ML19327C186
Person / Time
Site:	Fort Calhoun
Issue date:	11/15/1989
From:	OMAHA PUBLIC POWER DISTRICT
To:
Shared Package
ML19327C184	List: ML19327C183 ML19327C185 ML19327C186
References
NUDOCS 8911210123
Download: ML19327C186 (5)

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2.0 LIMITING CONDITIONS FOR OPERATION 2.7 E'ectrical Systems (Continued)

g. One of the four a-c instrument buses may be inoperable for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> provided the reactor protective and engineered 1 safaguards systems instrument channels supplied by the remaining three buses are all operable. 1

h. Two battery chargers.may be inoperable for up to S hours l y

provided battery charger No. I or No. 2 is operable,

, 1. Either one of the dies 11 generators may be inoperable for up ,;

L to seven days (total for both) during any month, provided the other diesel is started to verify operability, shutdown and controls are left in the automatic mode and there are no inoperable engineered safeguards components associated with the operable diesel generator.

J. Island buses .183A-4A,1838-48,. and 183C-4C may be inop?rable for "p to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> provided there are no inoperable safeguards components associated with the operable bus which are redundant to the inoperable bus.

k. Either one of the DC buses (Panels EE-8F and EE-8G) may be inoperable for up to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

. Either one of the DC Distribution Panels AI-41A and AI-418 u may be inoperable for up to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

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m. AC Instrument Panel AI-42A or AI-428 may be inoperable for up to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

l. n. The 161KV transmission line may be out of service a; 2 unit E operation may continue in the Power Operaticn Ocedition l (Mode 1) if the 345KV system and both diesC " i.e ators are operable. During the time the 161KV power .;u n.e i s unavailable, the requirement for the perforcance of the monthly surveillance tests on the diesel geierators or any ,

other te:t that could challenge the emergency actuation of i the diesei generators is deferred until seven (7) days after restoring the 161KV power source.

Basic i The electrical system equirent is arranged so that no singla failure can inactivate enough engineered sateauards to jeopardize the plant safety. The  ;

480 V safeguards are arranged on nine bus sections. The 4.16kV safeguards l are supplied from two buses.

L The normal source of audliary power with the plant at power for the L safeguards buses is from the nouse service power transformers being fed from L the 161 kV incoming lin? with on-site emergency power L.

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}; , j Discussion, Justification and No Significant  :

Hazards Consideration i 1

Discussion:

Description of Amendment Request to change the Technical Specification.

2.7(2)n,' Limiting Conditior, for Operation for the 161 KV transmission line.

To clarify operator actions in determining the remaining sources operability, eliminate the permissive to restart, and delete the notification requirements.

• Justi fi::ation:

The'0maha Public Power District (0 PPD) has reviewed'the adequacy of Technical

. Specification 2.7(2)n, Limiting Condition for Operation for plant operation with the 161 KV of fsite power out of service. This review was made as committed to in deference 2, to ensure the adequacy of this Technical Specification to direct OPPD action to insure reactor safety should the 161 KV line be removed from service (either by failure, maintenance, or grid conditions). The reliability of the 161KV transmission lir' is caasidered to be very good, demonstrating a 99.8% availability between 1973 and March 1989.

The longest outage was one of se.ven cays duration.

Based on the review, OPPD feels the following key points should constitute the specification, and define Fort Calhoun Operations:

a. The existing specification permits continued operation and should not be changed to add a time liinit. This is a safer course of action than a required shutdown because a turbine generator trip would cause a loss of offsite power. This loss of offsite power would cause the following:

1. Diesel generators start and energization of the safety busses.

2. Natural circulation cooling for core decay heat removal.

3. Decay heat removal from the steam generators via tte main steam safety valves due to the loss of the condenser.

4. A challenge to the automatic auxiliary feedwater system.

The plant cannot establish the normal hot shutdown configuration until 345 KV backfeed has been ev.ablished, condenser operations re-established, and reactor coolant pumps restarted.

This change reduces the possibility of complex transients and safety system challenges. The requirements of 2.7(2) to place the plant in hot shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and cold shutdown within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> apply, should the provisions of thi.; exception be violated.

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b. Generator synchronization with the 161 KV system out of service is not possible. '

OPPD believes that the perh.issive to go to Mode I with the 161 KV transmission line out of service snould be ramoved from the Technical Specification 2.7(2)n. '

It should-be-understood that Je present Technical Specification is g incorruct in that although the reactor could be taken to hot stcndby

' r J1 cal), the generator could not be synchronized to the power grid 4

i o .m supply house loads. This is because DS-T1 is a manual / motor i disconnect swit:h with no synchronization capability. The 345KV bus must be deenergizad before closing DS-T1. Removal of the 345KV bus would.deenergize all four RCPs and this would scram the plant. In other words, the exercise of starting op the plant without the 161KV power available is meaningless.

Note, however, that the plant may change modes and approach 300 0 F L without the diesel generators being operable under the current Technical Specification 2.7(1). This permissive is not affected by ,

this license :mendment. This is consistent with the safety analysis and allows operational flexibility,

c. To clarify operator e,ctions in determining the remaining power sources' operability, Technical Specificatic.12.7(2)n, was. changed to specify that the 345KV system and both diesel generators must be operable.

However, duri.,9 the time that the 161KV power supply is unavailable it is prudent not to perform surveillances on the two diesel generators.

The surveillance requires that all arotective devices including those bypassed on the emergency start to )e operable. The diesel generator is inoperable during the time a surveillance is being performed and the surycillance therefore removes one of the two remaining emergency power supplies. This is considered less safe than reliance on the most recent surveillance whea 161KV was available. Additiorally, i surveillance and tests 1 at will challenge the emergency actuation of l the diesel generators should . lot be performed. If in the performance of a surveillance the diesel is started, it would be necessary. to run the diesel until normal operating pressures and temoeratures were ,

achieved. As the diesel will no longer be in a standby mode, operator l action would be required to recover from those conditions which

. restrict automatic performance in a manner comparable to the norma' standby mode. Performance of these surveillance procedures could render the diesels unavailable as a source of emergency power should they be called upon to perform their emergency function. ..

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d. The notification requirements in Technical Specification 2.7(2)n. were

.el eted. The reporting requirements of this outage are the same as and will be made as other items now reported under 10 CFR 50.72 and 10 CFR 50.73. Follow-up information will provide further information on the extent of the loss, present status, and plans to restore the electric

. power system to its full capability as soon as practicable.

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Basis for No Significtnt Hazards Consideration:

This' proposed change does not involve significar,t hazards consideration because operation of Fort Calhoun Statica in accordance with this change

, woula not:

1. involve a significant ir. crease in the probability or consequence  ;

of an accident previously evaluatcd. This Change decreases the probability of an accident or event during the time the 161 KV transmission line is out of service. This is accomplished by clarifying the operability requirements of the remaining sources, removing the permissive to restart above 3000 F with the 161 KV line out.of service, and reducing challenges to safety systems.

create the pcssibility of a new or different kind of accident

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from any accident previously evaluated. It has Nen determined i that a new or different type of accident is not created because no new or different modes of operation are proposed for the plant.

3. involve a significant reduction in the margin of safety. This change does not result in a decrease in the margin of safety associated with the normal scurce of auxiliary power because challenges.to safety systems during the time the 161XV is out of service are minimized. Verifying power sources provides a higher level of assurance that alternate )ower sources are operable.

- Also, the unit will be shut down s1ould either of the diesel generator be unavailable when the 161KV is not available.

Therefore, based on the above considerations, OPPD has Jetermined that this change does not involve a significant hazards consideration.  :

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