ML20207D984

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Requests That NRC Exercise Enforcement Discretion to Allow Cpses,Unit 1 to Remain in Mode 1,power Operation,Without Having Performed Svc Test,Per SR 4.8.2.1d on Unit 1 Battery BT1ED2
ML20207D984
Person / Time
Site: Comanche Peak  Luminant icon.png
Issue date: 05/26/1999
From: Terry C, Walker R
TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
AL-95-05, AL-95-5, TXX-99131, NUDOCS 9906040128
Download: ML20207D984 (7)
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Log # TXX-99131 r

C File # 10010 7UELECTRIC Ref. # BUR I1600 4

C. Imace Ttrry senior nce President May 26,1999

& PrincipalNuclear Oficer U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)

DOCKET NUMBERS 50-445 AND 50-446 ENFORCEMENT DISCRETION FOR D.C. SOURCES, OPERATING REF:

1.

NUREG-1600," General Statement of Policy and Procedures for NRC Enforcement Actions," dated June 1995 2.

NRC Administrative Letter 95-05, Revision 1: Revisions to Staff Guidance for Implementing NRC Policy on Notices of Enforcement Discretion, dated February 19,1999 In accordance with the guidance provided by reference 1, TXU Electric

NRC Administrative Letter 95-05, Revision 1 (reference 2) provides guidance on the information to be included in a request for enforcement discretion. The sections i

below are arranged to correspond to that guidance.

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  • TXU Electric was formerly TU Electric. A license amendment request (LAR 99-003) l was submitted per TXX-99122, dated May 14,1999, to revise the company name contained in the CPSES operating licenses.

1 COMANCilE PEAK SIEAM ELECTRIC STATION

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P.O. Box 1002 Glen Rose, Texas 76043-1002

TXX-99131 Pa,ge 2 of 6

1. HEQUIREMENT/ REQUEST:

Surveillance Requirement 4.8.2.1d requires that the 125V D.C. station batteries be demonstrated OPERABLE by performing a battery service test at least once per 18 months, during shutdown. Surveillance Requirement 4.8.2.1e, states that a battery performance discharge test is allowed in lieu of the service test once per 60 month interval. For Unit 1 battery BT1ED2, the performance discharge test was incorrectly used twice within a 60 month intervalin lieu of the service test. In accordance with Surveillance Requirement 4.0.3, this failure to perform the Surveillance Requirement would constitute a noncompliance with the OPERABILITY requirements for the LCO.

In order that CPSES Unit i not be required to shutdown to allow surveillance performance, TXU Electric requests that the NRC exercise enforcement discretion to not enforce compliance with Surveillance Requirement 4.8.2.1d, by allowing on a one time basis, the substitution of the performance discharge test in lieu of the service test twice within the 60 month interval for battery BT1ED2.

2. CIRCUMSTANCES:

During the process of conducting reviews of battery surveillances, CPSES discovered that credit had been taken for the performance of a battery performance discharge test in lieu of a service test more frequently than is permitted by SR 4.8.2.1e.

Until the battery has reached 85% of its service life, a performance discharge test is only required once per 60 months (per SR 4.8.2.ie). SR 4.8.2.1e permits the substitution of this performance discharge test for the SR 4.8.2.1d required service test once per 60 month interval. Generally that means that each required performance discharge test could be substituted for a required service test. However,if the battery is considered degraded or after 85% of its service life, performance discharge tests of the battery are required on an 18 month frequency per SR 4.8.2.1f. Battery BT1ED2 reached 85% of its service life in April 1996 just prior to 1RFOS. A performance discharge test was conducted per SR 4.8.2.1f in 1RFOS. It was mistakenly assumed that each performance discharge test could be credited for a service test after 85%

service life. Similarly, a performance discharge was substituted for a service test in 1RFO6. Since SR 4.8.2.1e permits substitution only once per 60 months test interval, and since 1RFOS and 1RFO6 are in the same 60 month interval, this substitution was not valid. The invalidity of the substitution was not recognized at the time.

TXU Electric believes that crediting the performance discharge test in 1RFO6 was acceptable and that compliance with the requirements of SR 4.8.2.1d for battery BT1ED2 was re-established by the performance of that test. However, due to the uncertainty of the situation we have conservatively chosen to consider that the surveillance is not current.

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TXX-99131 Pa,ge 3 of 6

3. SAFETY SIGNIFICANCE AND POTENTIAL CONSEQUENCES:

The safety function of the batteries is to automatically pick up required DC loads in the event of loss of normal power to the battery chargers. The service test and the performance discharge test surveillances provide assurance that the batteries are capable of performing their safety function. The battery service test is a special test of battery capability to satisfy the design requirements (battery duty cycle) of the DC electrical power system. The discharge rate and test length correspond to the design duty cycle requirements as specified in the FSAR. The battery performance discharge test is a test of battery capacity performed to an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> discharge rate as specified by the manufacturer, and is intended to determine overall battery capacity and battery degradation due to age and usage. The performance discharge test is generally considered a more severe test of battery capacity than the service test because it removes more ampere-hours. Partially because of this it is allowed to be substituted for the service test once per 60 month interval. However, the service test has higher short term ampere requirements and thus the performance discharge test does not completely envelope the service test requirements.

The batteries are designed with sufficient margin to ensure that they are capable of powering their required loads throughout the design life of the batteries. The batteries are normally replaced when the capacity of the battery based on the performance discharge test approaches 80%. While the performance discharge test does not specifically test at the higher ampere rating of the service test, it would be expected that if the battery were to develop problems associated with the ability to provide those higher ampere ratings, it would be more likely to occur near the end of service life of the battery (i.e.,80% capacity). The performance discharge test capacities of battery BT1ED2 were 97.2% and 95.4% for 1RFOS and 1RFO6 respectively. With the available capacity margins indicated by these results the battery would certainly have passed a service test. In addition, during the service test the battery voltage is monitored. The margin between the recorded end of test voltage and the minimum required voltage provides an indication of the ability of the battery to sustain some degradation (e.g., normal battery aging) and still meet the service test current requirements. The last service test performed on BT1ED2 was during 1RF04. For that test the battery's end of test voltage was 115.3V compared to a minimum required 105V. The end of test voltage for an earlier service test conducted during 1RF02 was 115.6V. The large margin (10.3V) between minimum required voltage and the end of test voltage for the service test in 1RF04 and the small degradation in end of test voltages between 1RF02 and 1RFO4 (0.3V) provides additional confidence that the battery would have passed service tests if they had been performed in 1RFO5 or 1RFO6.

TXU Electric believes that the crediting the performance discharge test in lieu of the required service test is an acceptable alternative to requiring a Unit 1 shutdown to perform the missed surveillance.

Based upon the results of a Probabilistic Risk Assessment (PRA) evaluation, even using conservative assumptions with respect to the battery reliability, it is concluded that the change in risk can be considered to be non-risk significant. When one considers the risk related with transition and shutdown, it can be concluded that the undesirable transients (associated with transition and shutdown) pose greater risk than remaining at power while crediting the battery performance discharge test in lieu of the required service test.

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TXX-99131 Page 4 of 6

4. NO SIGNIFICANT HAZARDS CONSIDERATION:

l TU Electric has considered the criteria for assessing the potential of creating a significant hazards consideration with the exercising of enforcement discretion. In evaluating if discretion in enforcement constitutes a significant hazard the criteria of 10CFR50.92(c)is discussed below:

1.

Do the proposed changes involve a significant increase in the probability or consequences of an accident previously evaluated?

Crediting the battery performance discharge test in lieu of the required service test will not impact the ability of the battery to perform its safety functions.

Therefore, this change will not increase the probability or consequences of an accident previously evaluated.

2.

Do the proposed changes create the possibility of a new or different kind of accident from any accident previously evaluated?

Crediting the performance discharge test in lieu of the required service test will not create a new or different kind of accident.

3.

Do the proposed changes involve a significant reduction in a margin of safety?

Crediting the performance discharge test in lieu of the required service test does not create any new failure scenarios and no margin is expected to be reduced.

As such, there is no reduction in any margin of safety.

In summary, TXU Electric has determined that crediting the performance discharge test in lieu of the required service test does not involve a significant hazard consideration and will not be of potential detriment to the public health and safety.

5. ENVIRONMENTAL CONSEQUENCES:

The request only involves crediting the battery performance discharge test in lieu of the required service test. This activity is limited to the plant and will not result in any unplanned releases that could impact the environment.

6. COMPENSATORY ACTIONS:

An engineering evaluation was performed, based on data available from the recent performance discharge tests (e.g., battery parameters such as connection resistances and individual cell voltages). A comparison of cell connection resistance readings and cell voltage readings for BT1ED2 was made.

The resistance data was taken from connection surveillance tests performed in 1RF04, 1RF05, and 1RF06. The resistance readings show no overall signs of degradation.

The resistance readings of each intercell connector and interconnecting cables are taken and must be within tolerance. Connections that are not within tolerance must be reworked. The data from the above tests shows that very few connections have required rework. Four connections required rework during 1RF04, three during 1RF05, and two during 1RF06. Where rework was required, the deviations were insignificant

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TXX-99131

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Page 5 of 6 when compared to overall resistances and were well below Technical Specification limitations for individual cell readings. Specifically, for the two 1RFO6 out of tolerance readings, the acceptance criteria were 28 and 41 micro-ohms. The as-found readings were 30 and 44 micro-ohms respectively. The as-left readings were 19 and 40 micro-1 ohms respectively. Weekly visualinspections, which include inspections for cleanliness and connection corrosion, are performed. Corrective actions are taken on any problems found. These inspections help to ensure that connections are not degrading between discharge tests.

A comparison of cell voltages between the service test conducted in 1RF04 and the discharge performance test conducted in 1RF06 was made. The individual cell voltage readings at the end of the service test during 1RF04 were all in the range of 1.89 to 1.93 volts. The individual cell voltage readings at similar points in the performance discharge test (based on total amp-hour discharge) during 1RF06 ranged from 1.89 to 1.91 volts.

In addition, the SR 4.8.2.1b.2) inspection for visible corrosion of battery terminals and connectors was completed on April 28,1999. The inspection found no evidence of corrosion.

These factors give reasonable assurance that the resistances of the battery connections and the individual cell performances are such that the battery would be capable of delivering the required current and voltage to power the loads on the battery.

7. DURATION:

The requested duration is brsed upon the time required for the NRC to process a proposed change to the technical specifications. The requested duration is to commence upon approval of this enforcement discretion request and to expire upon t

J disposition of the proposed license amendment

8. SORC REVIEW:

This activity has been reviewed and approved by the Station Operations Review Committee (SORC).

9. CRITERIA FOR EXERCISING ENFORCEMENT DISCRETION:

Reference 2 provides the criteria for exercising enforcement discretion for an operating plant as follows:

For an operating plant, the NOED is intended to (a) avoid undesirable transients as a result of forcing compliance with the license condition and, thus minimize potential safety consequences and operational risk or (b) eliminate testing, inspection, or system realignment that is inappropriate for the particular plant conditions.

This criteria reflects the NRC's policy as provided in reference 1.

Initiating a shutdown to comply with the subject Technical Specifications would subject CPSES to an unnecessary transient which poses greater safety consequences than

TXX-99131 Page 6 of 6 crediting the battery performance discharge test in lieu of the required service test.

Further, the service test cannot be performed while the plant is in operation.

10. PROPOSED TECHNICAL SPECIFICATION CHANGES:

A separate license amendment request (LAR) will be submittad by May 28,1999, under a different letter. This LAR will request a one time exception to allow crediting the battery performance discharge test in lieu of the required service test. This one time exception expires prior to entry into MODE 4 following the next Unit 1 outage of sufficient duration to perform a service test. A draft markup of the current TS revisions is attached.

CONCLUSION:

TXU Electric requests the NRC grant the requested enforcement discretion to allow CPSES to credit the performance of Surveillance Requirement 4.8.2.1f, (performance discharge test)in lieu of Surveillance Requirement 4.8.2.1.d (service test) twice within the 60 month interval for battery BT1ED2.

This communication contains the following new commitment which will be completed as noted:

CDF Number Commitment 27177 A separate license amendment request (LAR) will be submitted by May 28,1999, under a different letter. This LAR will request a Technical Specification change which provides on a one time basis, for battery BT1ED2, that the performance discharge test may be performed in lieu of the battery service test required by Specification 4.8.2.1d, twice within a 60 month interval. This one time exception expires prior to entry into MODE 4 following the next Unit 1 outage of sufficient duration to perform a service test.

Sincerely, h.

C. L. Terry By:

Roger D." Walker Regulatory Affairs Manager BSD/bd Attachment c - Mr. E. W. Merschoff, RIV Mr. D. H. Jaffe, NRR Mr. J. l. Tapia, RIV CPSES Resident inspectors

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Att:: chm: nt to TXX-9'9131 Pago 1 of 1 ELECTRICAL POWER SYSTEMS SURVEILLANCE REQUIREMENTS (Continued) 1)

The parameters in Table 4.8-2 meet the Category B limits, 2)

There is no visible corrosion at either terminals or connectors, or the connection resistance of these items is less than 150 x 104 ohm,and 3)

The average electrolyte temperature of 12 connected cells is above 70 F.

c.

At least once per 18 months by verifying that:

1)

The cells, cell plates, and battery racks show no visual indication of physical damage or abnormal deterioration, 2)

The cell-to-cell and terminal connections are clean, tight, and coated with anticorrosion material, 3)

The resistance of each cell-to-cell and terminal connection is less 4

than or equal to 150 x 10 ohm,and 4)

The battery charger will supply at least 225 amperes at 130 volts for at least 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

d.

At least once per 18 months, during shutdown, by verifying that the battery capacity is adequate to supply and maintain in OPERABLE status all of the actual or simulated emergency loads for the design duty cycle when the battery is subjected to a battery service test; e.

At least once per 60 months, during shutdown, by verifying that the battery capacity is at least 80% of the manufacturer's rating when subjected to a performance discharge test. Once? per 60-month interval this performance discharge test may be performed in lieu of the battery service test required by Specification 4.8.2.1d.; and f.

At least once per 18 months, during shutdown, by giving performance discharge tests of battery capacity to any battery that shows signs of degradation or has reached 85% of the service life expected for the application. Degradation is indicated when the battery capacity drops more than 10% of rated capacity from its average on previous performance tests, or is below 90% of the manufacturer's rating.

  • On a one time basis,.for battery BT1ED2, this performance discharge test may be performed in lieu of the battery service test required by Specification 4.8.2.1d, twice within a.60 month interval. This one time exception expires prior to entry into MODE 4 following the next Unit 1_ outage of sufficient duration to perform a. service test.
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