ML17332A293

Safety Evaluation Supporting Amend 166 to License DPR-74

ML17332A293
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Site:	Cook
Issue date:	09/06/1994
From:	Office of Nuclear Reactor Regulation
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. UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2055&4001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 166 TO FACILITY OPERATING LICENSE NO.

DPR-74 INDIANA MICHIGAN POWER COMPANY DONALD C.

COOK NUCLEAR PLANT UNIT NO.

2 DOCKET NO. 50-316

1.0 INTRODUCTION

By letter dated August 18,

1994, the Indiana Michigan Power Company (the licensee) requested an amendment to the Technical Specifications (TS) appended to Facility Operating License No.

DPR-74 for the Donald C.

Cook Nuclear Plant, Unit No. 2.

The proposed amendment would allow extension of the due date for Surveillance Requirements 4.8.2.3.2.c.3 and 4.8.2,3.2.d for the Unit 2 CD battery from September 7,

1994, until just prior to core reload in the upcoming refueling outage.

The same extension is requested for Surveillance Requirement 4.8.2.4.2, which references TS 4.8.2.3.2.

The licensee also proposed to add a

new footnote to these specifications, which will reference a

new TS 4.0.9.

The new specification would state:

"By specific reference to this section, those surveillances which must be performed on or before September 7,

1994, and are designated as 18-month surveillances may be delayed until just prior to core reload in the Unit 2 Cycle 9-10 refueling outage."

TS section 3/4.8.2.4 contains the DC-distribution requirements for Modes 5 and 6.

One of the two station batteries and one of its two associated chargers are required to be operable in these modes.

With no battery or charger

operable, containment integrity must be established within eight hours.

TS 4.8.2.3.2.c.3 requires that the battery charger be demonstrated capable of supplying at least 140 amps at greater than or equal to 250 volts for at least four hours.

This test must be conducted every 18 months.

TS 4.8.2.3.2.d requires that a battery service test be conducted every 18 months, specifically with the unit in Modes 5 or 6.

TS 4.8.2.4.2 requires, for Modes 5 and 6 operation, that the battery and charger be demonstrated operable per TS 4.8.2.3,2, The Unit 2 refueling outage is scheduled to begin September 6,

1994.

The TS 4.8.2.3.2,c.3 and 4.8.2.3.2.d surveillances, which are required for Modes 5

and 6 per TS 4,8.2.4.2, are due on September 7,

1994.

Due to the nature of the workscope for the outage, work on Train B, which includes the 2-AB

battery, was scheduled for the beginning of the outage.

However, the performance of the required surveillances on the Train A (2-CD) batteries and charger would cause both DC trains to be inoperable.

Per TS 3.8.2.4, this e<OVOVOaS8 9OOeoSV PDR ADOCK 050003l6 P

PD~R would require containment integrity be established and therefore, shut down all outage activities.

The requested relief would allow the licensee to maintain the 2-CD battery and charger operable, and avoid having to establish containment integrity.

Therefore, the licensee requested relief from the requirement to perform the TS 4.8.2.3.2.c.3 and 4.8.2.3.2.d surveillances on the CD battery and associated chargers in order to avoid approximately a one week addition to the refueling outage length.

The licensee has stated that all delayed surveillances would be completed prior to reload of the core.

2.0 EVALUATION Each unit at D.C.

Cook has two independent and redundancy main 250 Vdc trains which supply power for a duplicated set of engineered safety systems.

The trains are designated A or Green Train (CD batteries) and B or Red Train (AB batteries).

Under normal conditions with a unit at power, both DC trains are energized with one charger in each train, connected and supplying electricity to its plant safety system loads.

In addition to supplying train loads, the connected charger maintains (or restores) the charge on the batteries via its float voltage capability.

The second charger serves as backup for each train in case of first charger failure (or loss of its 600 volt ac input power).

In an emergency situation involving the loss of ac input voltage to both chargers (for whatever reason),

the fully charged batteries then takeover the task of providing a reliable and continuous supply of DC power to the plant safety systems as needed.

A battery service test is a special test of battery capability, as found, to satisfy the design requirements (battery duty cycle) of the DC electrical power system.

At D.C.

Cook the test is eight hours in duration, and the load profile is in accordance with the battery sizing calculations.

In the application, the licensee provided the following information on the recent surveillance performed on the 2-CD battery, 1.

The 2-CD battery was capacity tested in the fall of 1992, with a resultant capacity of 110'ince the minimum acceptable

capacity, per IEEE 450, is 80%, the test results represent a

30% capacity margin.

Batteries of the type used at Cook Nuclear Plant might lose up to approximately 1% capacity per year, depending on the battery age.

Assuming 1% capacity loss per

year, the expected capacity through the fall of 1994 would be approximately 108%, which represents a

28% capacity margin.

2.

The 2-CD battery was service tested in the spring of 1992 with a terminal voltage (after the required 8-hour discharge) of 226 volts.

The minimum acceptable terminal voltage is 210 volts, which exceeds the minimum required to support plant loads.

Haintenance records indicate that the service test terminal voltage decreases no more than 3 volts per 18-month period.

Assuming worst-case and conservatively using 36 months as the time between testing, the minimum terminal voltage in the fall of 1994 would be no less than 220 volts, which is well above the minimum of 210 volts.

3.

The average electrolyte temperature for the 2-CD battery was 83'F over the last 18 months.

This value is well within the design operating range for the battery.

4.

The battery room temperatures are checked every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for a minimum acceptable room temperature of 70'F.

Since establishing this temperature and implementing its monitoring in the shift tour guidelines in 1992, there have been no instances where the 2-CD battery room temperature has fallen below 70 F.

5.

Since their installation in 1988, no battery charger has failed the 18-month surveillance.

The licensee also noted that the relief requested for the 2-CD battery and chargers is for the requirements of TS 4,8.2.3.2,c,3 and 4.8,2.3.2,d only.

The weekly and quarterly surveillances performed on the battery will continue on their normal schedule as required by the TS.

These surveillances check the battery cells for correct specific gravity, cell and overall voltage, float

voltage, and electrolyte level.

Also, the requirements of TS 4.8.2.3.2.c.

1 and 4.8.2.3.2.c.2 will be performed by their due date.

These are 18-month surveillances which ensure that there is no visual indication of physical damage or abnormal degradation of the battery and racks, and that the battery connections are clean, tight, free of corrosion and coated with anti-corrosion material.

In addition, it is noted that the relief is requested for a period when the unit will be in a shutdown condition.

Emergency loads on the 2-CD battery during Nodes 5 and 6 are a fraction of those during operation in Modes 1

through 4.

Specifically, the three turbine generator lube and seal oil pumps, which represent nearly one-half of the load on the battery (185 amps out of 398 amps) would not be required.

As such, should the battery be called upon to supply emergency loads during the outage, only a portion of the available capacity would be needed.

Additionally, there are two chargers per battery, with only one required per TS.

Should the inservice charger become inoperable, an annunciator in the control room would alert the operators, who would then place the backup charger in service.

The chargers receive emergency power from the emergency diesel generators, thereby increasing the reliability of the DC system in the event of a loss of offsite power.

Core reload for the Unit 2, Cycle 9-10 refueling outage is expected to occur by October 10, 1994.

Therefore, the total period of time that the licensee has requested the relief to be in effect is expected to be about one month.

In a telephone conversation with the staff on August 30, 1994, the licensee agreed that the latest date by which the surveillance would be done is November 7, 1994.

Considering the maintenance records for the weekly, quarterly, 18-month, and 60-month surveillances performed on the battery per TS 4.8.2.3.2, the 2-CD battery has demonstrated high capacity with no indication of problems.

Based on the short duration of the request, the good past surveillances, and the surveillances which will continue to be performed, the staff considers the requested surveillance relief to be acceptable.

3.0 EMERGENCY CIRCUMSTANCES In its August 18, 1994, application, the licensee requested that the amendment request be treated as an emergency amendment because the relief is needed by September 7,

1994 to avoid an extension to the refueling outage.

In accordance with 10 CFR 50.91(a)(5),

the licensee provided the following information regarding why this emergency situation occurred and why they could not avoid the situation.

In 1992, both units of Cook Nuclear Plant were shut down for refueling.

Unit 2 was the first unit shut down, in February, 1992.

The original plan was that the Unit 1 outage would begin after Unit 2 was returned to service.

However, during startup for the present Unit 2 cycle (Cycle 9) in July 1992, the unit experienced severe turbine-generator vibration problems that required refurbishment of the Unit 2 generator rotor, The vibration problems resulted in the unit being down approximately six months.

Thus, Unit 2 was not returned to service until after the Unit 1 refueling outage was completed.

The 2-CD battery and chargers were surveillance tested during the refueling

outage, and then again in October 1992 to help ensure that the surveillance would not expire during Cycle 9.

In order to provide sufficient separation between the next refueling outages, the decision was made to run Unit 2 at a

reduced power level.

The plan was to extend Unit 2, Cycle 9, by approximately five months, with an anticipated outage start date of August 6, 1994.

In order to support this, surveillance interval extensions were requested from the NRC for surveillances due on or before August 13, 1994.

The requested surveillance interval extensions were approved by the NRC via Amendments

158, 159, and 162.

Relief for the 2-CD battery and charger surveillances was not requested because these surveillances had a due date of September 7,

1994, which was after the original anticipated outage start date.

The outage start date was subsequently moved to early September due to projected AEP system demand in August 1994.

In February 1994 Unit 2 was shut down for replacement of the main generator rotor due to additional vibration problems.

The surveillances for which extensions are requested were not performed during this down time.

This is because the impact of the surveillance due dates relative to the outage schedule were not evident at that time.

The first detailed, resource leveled outage schedule was not released until August 5, 1994.

The licensee's typical scheduling strategy is to look at the total work scope to determine which train of equipment will require the most amount of work, and to schedule that train first.

This is so that problems that may arise are identified earlier in the outage, allowing the most flexibility in resolving them.

During this refueling outage, the 2-AB battery (Train B) will be

replaced, so Train B was scheduled first.

The decision to schedule Train B

was also supported by the fact that blackout testing following each electrical train outage impacts certain support functions required for other outage evolutions, such as containment lighting and polar cranes.

These functions are impacted more by a Train A outage than a Train B outage.

The 2-CD battery surveillance expires on September 7,

1994.

The 2-AB battery surveillance expires on September 18, 1994.

The schedule as outlined has the Train B power outage beginning September 7 and ending September 27.

The Train A work commences September 27 and ends October 8.

The outage plan calls for the reactor core to be completely offloaded, This is expected to be completed by September 21, 1994, with reload expected to begin October 10, 1994.

With this schedule and the existing TS surveillance due dates, on September 7 neither DC train would be operable and therefore, containment integrity would be required per TS 3.8.2.4.

This essentially shuts down all outage activities, because of the inability to open a containment service penetration or to move equipment through an airlock.

The requested relief will allow the licensee to maintain the 2-CD battery and charger operable, and thus avoid having to establish containment integrity.

The licensee's outage scheduling process did not provide a mechanism to tie information regarding surveillance due dates to the

schedule, The first detailed, resource leveled version of the outage schedule was not issued until August 5, 1994.

The scheduling problem was identified on August 10, 1994.

At that point, the licensee began investigating various options.

By August 15, the licensee determined that all options but emergency TS relief would result in an early shutdown of the unit and/or add considerably to the outage length.

The release of the detailed outage schedule is the culmination of approximately 13 months of work.

In addition to consideration of minimization of outage length, the schedule also reflects consideration of shutdown risk, in order to minimize the risk to public health and safety.

The licensee determined that insufficient time was available to permit rewriting the schedule with confidence to allow work on Train A first.

Therefore, without the requested relief, the licensee would have to perform the surveillance on the 2-CD battery and charger at the beginning of the outage, prior to removing the 2-AB battery from service.

The battery test involves demonstrating the ability of the battery to supply simulated or actual loads for eight hours.

Because the battery is drawn down during the test, it becomes inoperable.

There are redundant chargers for'each battery, with only one charger per battery required per TS.

A charger could be tested at power while disconnected from the battery.

However, this lessens redundancy built into the DC system, and would involve a substantial rewrite of the surveillance procedure.

Typically, the chargers are tested in conjunction with the service test of the battery, during the outage.

The chargers are used sequentially to recharge the battery following the drawdown, thereby satisfying the charger surveillance.

The total duration time of the testing typically approaches one week.

This is due to the lineup and restoration

times, as well as the approximately 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> required to recharge the battery following the service test.

Performance of the 2-CD surveillance at the beginning of the outage will therefore add approximately one week to the outage length.

In summary, the licensee has requested the relief due to a scheduling conflict which impacts the required operability of the DC power systems.

Due to the nature of the conflict, it could not have been identified in an adequate timeframe to plan alternative actions.

Lacking the requested relief, the licensee would either have to shut the unit down prematurely or delay restart from the outage.

Accordingly, the Commission has determined that there are emergency circumstances warranting prompt approval by-the Commission pursuant to 10 CFR 50.91(a)(5).

4.0 FINAL NO SIGNIFICANT HAZARD'S CONSIDERATION DETERMINATION The Commission's regulations in 10 CFR 50.92(c) state that the Commission may make a final determination that a license amendment involves no significant hazards consideration if operation of the facility in accordance with the amendment would not:

(1) involve a significant increase in the probability or consequences of an accident previously evaluated; or

'(2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety.

The proposed changes do not involve a significant hazards consideration because the operation of the D.C.

Cook Nuclear Plant in accordance with the proposed changes would not:

(1) Involve a si nificant increase in the robabilit or conse uences of an accident reviousl evaluated The previous maintenance history on the 2-CD battery and chargers provides confidence that the battery and chargers will remain operable during the extension period.

Weekly and quarterly checks of the battery will continue to be performed, as required by T/S 4.8,2.3.2.

Also, the 18-month surveillances of the battery for signs of physical damage or abnormal deterioration, as well as the 18-month check of the cell-to-cell and terminal connections will be performed.

Therefore, based on these considerations, the staff concludes that the proposed surveillance interval extensions will not involve a significant increase in the probability or consequences of an accident previously evaluated.

(2) Create the ossibilit of a new or different kind of accident from an accident reviousl evaluated.

The previous maintenance history on the 2-CD battery and chargers provides confidence that the battery and chargers will remain operable during the extension period.

Thus, the proposed change represents no new operating condition or configuration for the plant, Therefore, the proposed extension does not create the possibility of a new or different kind of accident from any previously evaluated.

(3) Involve a si nificant reduction in a mar in of safet The previous maintenance history on the 2-CD battery and chargers provides

, confidence that the battery and chargers will remain operable during the brief period of the requested extension.

Weekly and quarterly checks of the battery will continue to be performed, as required by T/S 4.8.2.3,2.

Also, the 18-month surveillances of the battery for signs of physical damage or abnormal deterioration, as well as the 18-month check of the cell-to-cell and terminal connections will be performed.

These considerations lead the staff to conclude that the proposed surveillance interval extensions will not involve a significant reduction in a margin of safety.

5.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Michigan State official was notified of the proposed issuance of the amendment.

The State official had no comments.

6. 0 ENVIRONMENTAL CONSIDERATION The amendment changes a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes to the surveillance requirements.

The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released

offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.

The Commission has made a final no significant hazards consideration determination with respect to this amendment.

Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Pursuant to 10 CFR 51.22(b),

no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

7.0 CONCLUSION

The staff has concluded, based on the considerations discussed above that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed

manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor:

John B. Hickman, NRR Date:

September 6,

1994