ML20077A998

Forwards Clarification of Util Intended Application of 931123 Proposed TS Change Re Electrical Power Sys

ML20077A998
Person / Time
Site:	South Texas
Issue date:	11/17/1994
From:	Groth J HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ST-HL-AE-4934, NUDOCS 9411280212
Download: ML20077A998 (10)

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The Light

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c o mp a nyS uth Texas Project Dectric Generadng Station E O. Box 289 WadswortMesas m83 Houston Lighting & Power November 17, 1994 ST-HL-AE-4934 File No.: G09.06 10CFR50.90, 10CFR50.92, 10CFR51 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 South Texas Project Units 1 & 2 Docket Nos. STN 50-498, STN 50-499 Revision to Proposed Changes to the South Texas Project Technical Specification (TAC NOS. M88291 and M88292)

Reference:

1) Letter from HL&P dated November 23, 1993 (ST-HL-AE-4625) TAC No. M88291/M88292

2) Letter from HL&P dated June 6, 1994 (ST-HL-AE-4736) TAC No. M88291/M88292 In a letter dated November 23, 1993 (Reference 1), Houston Lighting

& Power (HL&P) proposed to amend Facility Operating Licenses NPF-76 and NPF-80 for South Texas Project Units 1 and 2 by revising Technical Specification 3.8.1.1, Electrical Power System - A.C.

Sources - Operating. After discussions with the Nuclear Regulatory Commission staff, a supplement to these changes was submitted by a letter dated June 6, 1994 (Reference 2). Based on further discussions with the Nuclear Regulatory Commission staff, a number of items that needed further clarification were identified. The following are clarifi"-tions of Houston Lighting & Power's intended application of the r osed Technical Specification changes.

1. Should the Dies.1 Fuel Oil fail to meet the acceptance criteria identified in the Diesel Fuel Oil Program, the affected Diesel Generator will be declared inoperable due to an inoperable support system.

2. Houston Lighting & Power has committed in a letter dated September 6, 1994 to the conversion of the current South Texas Project Technical Specifications to the Improved Standard Technical Specification Format. During this conversion the South Texas Project will incorporate a Limiting Condition for  ;

Operation (LCO), consistent with the Improved Standard Technical Specifications, to address the Diesel Fuel Oil testing program.

9411280212 941117 PDR ADOCK 05000498 P .

PDR TSC-94\94-H9.001 Project Manager on Behalf of the Participants in the South Texas Project . J

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Houston Lighting & Power Company South Teia: Project Electric Generating Station ST-HL-AE-4934 ,

File No.- G09.06 l Page 2 l

3. The following are Houston Lighting & Power's proposed exceptions to the ASTM standards associated with the testing of Diesel Fuel Oil.

a. The sample containers used for sampling fuel oil will be prepared using ASTM D-2276 method with the exception of capping the bottle with plastic film rinsed with filtered petroleum ether.

b. The viscometer bath temperature will be allowed a 0.05* C variation during the performance of Viscosity Kinematic Method, ASTM D445.

c. The temperature of the water bath used during the performance of Determination of Water and Sediment in Oil, will be maintained at 120 2* F, but is not required to be recorded.

d. An alternate thermometer that meets the accuracy requirements of ASTM D93 will be used during the Determination of Flash Point in Oil.

e. The Determination of Flash Point in Oil testing analysis results will not be corrected for barometric pressure unless the Flash Point falls below 130* F.

f During the performance of ASTM D2276, Determination of Particulate Contamination in Fuel Oil, the sample bottle will be wiped clean in the region of the cap, and a clean watch glass will be used to cover the funnel opening of the assembled filtration apparatus.

g. The results of the performance of ASTM D2276, Determination of Particulate Contamination in Fuel Oil, will be recorded to two significant digits.

4. The Nuclear Regulatory Commission staff has requested several changes to the bases submitted with this amendment request.

Houston Lighting & Power has agreed with the proposed changes and the tev: sed pages are attached.

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• I Houston Lighting & Power Company South Texas Project Electric Generating Station ST-HL-AE-4934 )

File No.. G09.06 l Page 3 l l

i If you should have any questions concerning this matter, please contact Mr. S. M. Head at (512) 972-7136 or me at (512) 972-8664.

J.'F. Groth Vice President Nuclear Generation JFG/ pas Attachments:

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~ Houston Lighting & Power Company ST-HL-AE-4934 South Teias Project Electric Generating Station File No.:G09.06 Page 4 C

Leonard J. Callan Rufus S. Scott Regional Administrator, Region IV Associate General Counsel U. S. Nuclear Regulatory Commission Houston Lighting & Power Company 611 Ryan Plaza Drive, Suite 400 P. O. Box 61067 Arlington, TX 76011-8084 Houston, TX 77208 Thomas W. Alexion Institute of Nuclear Power Project Manager Operations - Records Center U. S. Nuclear Regulatory Commission 700 Galleria Parkway Washington, DC 20555-0001 13H15 Atlanta, GA 30339-5957 David P. Loveless Dr. Joseph M. Hendrie Sr. Resident Inspector 50 Bellport Lane c/o U. S. Nuclear Regulatory Comm. Bellport, NY 11713 P. O. Box 910 Bay City, TX 77404-0910 Richard A. Ratliff Bureau of Radiation Control J. R. Newman, Esquire Texas Department of Health Newman, Bouknight & Edgar, P.C. 1100 West 49th Street STE 1000, 1615 L Street, N.W. Austin, TX 78756-3189 Washington, DC 20036 U. S. Nuclear Regulatory Comm.

K. J. Fiedler/M. T. Hardt Attn: Document Control Desk City Public Service Washington, D. C. 20555-0001 P. O. Box 1771 San Antonio, TX 78296 J. C. Lanier/M. B. Lee J. R. Egan, Esquire City of' Austin Egan & Ar.sociates, P.C.

Electric Utility Department 2300 N Street, N.W.

721 Barton Springs Road Washington, D.C. 20037 Austin, TX 78704 G. E. Vaughn/C. A. Johnson Central Power and Light company P. O. Box 2121 Corpus Christi, TX 78403 1

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Attachment F Page 2 of-13 The OPERABILITY of the AC electrical power sources is consistent with the initial assumptions of the Accident analyses and is based upon meeting the design basis of the unit. This results in maintaining at least one train of the onsite or offsite AC sources OPERABLE during Accident conditions in the event of:

a. An assumed loss of all offsite power or all onsite AC power; and

b. A worst case single failure.

The AC sources satisfy Criterion 3 of NRC Policy Statement.

LCO Two qualified circuits between the offsite transmission network and the onsite Class 1E Electrical Power System and separate and independent DGs for each train ensure availability of the required power to shut down the reactor and maintain in a safe shutdown condition after an anticipated operational occurrence (.AOO) or a postulated DBA.

Qualified offsite circuits are those that are described in the FSAR and are part of the licensing basis for the unit.

Each offsite circuit must be capable of maintaining rated frequency and' voltage, and accepting required loads during an accident, while connected to the ESF buses.

Each DG must be capable of starting, accelerating to rated speed and.

voltage, and connecting to its respective ESF bus on detection of bus undervoltage. This will be accomplished within (10] seconds. Each DG must also be capable of accepting required loads within the assumed loading sequence intervals,' and continue to operate until offsite power can be restored to the ESF buses. These capabilities are required to be met from a variety of initial conditions such as DG in standby with the engine hot, DG in standby conditions, and DG operating in parallel test mode.

The AC sources in one train must be separate and independent (to the extent possible) of the AC sources in the other train. For the DGs, separation and independence are complete.

For the offsite AC sources, separation and independence are to the ,

extent practical. A circuit may be connected to more than one ESF bus, with fast transfer capability to the other circuit OPERABLE, and not violate separation criteria. A circuit that is not connected to an ESF bus is required to have OPERABLE fast transfer interlock ,

mechanisms to at least two ESF buses to support OPERABILITY of that i circuit.

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Attachment F Page 3 of 13 APPLICABILITY The AC sources are required to be OPERABLE in MODES 1, 2, 3, and 4 to ensure that:

a. Acceptable fuel design limits and reactor coolant pressure boundary limits are not exceeded as a result of anticipated operational occurrences (AOOsi or abnormal transients; and

b. Adequate core cooling is provided and containment OPERABILITY and other vital functions are maintained in the event of a postulated DBA.

The AC power requirements for MODES 5 and 6 are covered in LCO 3.8.2, "AC Sources-Shutdown."

3.8.1.1 Action a.

To ensure a highly reliable power source remains with one offsite circuit inoperable, it is necessary to verify the OPERABILITY of the remaining required offsite circuit on a more frequent basis. However, if a second required circuit fails 4.8.1.1.1.a, the second offsite circuit is inoperable, and Action e, for two offsite circuits inoperable, is entered.

TS 3.8.1.1 Action b.

To ensure a highly reliable power source remains with one diesel generator inoperable, it is necessary to verify the OPERABILITY of the required offsite circuits on a more frequent basis. However, if a required circuit fails 4.8.1.1.1.a, the offsite circuit is inoperable, and Action c, for one offsite circuit and one diesel-generator inoperable, is entered. Action b provides an allowance to avoid I unnecessary testing of OPERABLE diesel generators. If it can be determined that the cause of the inoperable diesel generator does not i exist on the OPERABLE dieeal generators, and is an independently q testable component or an inoperable support system, then surveillance l requirement 4.8.1.1.2.a.2 does not have to be performed. ]

l TS 3.8.1.1 Action c. '

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To ensure a highly reliable power source remains with one offsite circuit and one diesel generator inoperable, it is necessary to verify the OPERABILITY of the remaining required offsite circuit on a more frequent basis. However, if a second required circuit fails 4.8.1.1.1.a, the second offsite circuit is inoperable and LCO 3.0.3 l should be entered. Action c provides an allowance to avoid unnecessary testing of OPERABLE diesel generators. If it can be determined that the cause of the inoperable diesel generator does not  !

exist on the OPERABLE diesel generators, and is an independently testable component or an inoperable support system, then surveillance requirement 4.8.1.1.2.a.2 does not have to be performed.

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Attachment F Page 4 of 13 TS 3.8.1.1 Action d.

Provides assurance that a loss of offsite power, during the period.

'that a diesel generator is inoperable, does not result in a complete loss of safety function of critical systems. In this condition the remaining OPERABLE diesel generators and offsite circuits are adequate to supply electrical power to the onsite Class 1E Distribution System.

Thus, on a component basis , single failure protection for the required feature's function may be lost; however, function has not been lost. Discovering one required diesel generator inoperable coincident with one or more inoperable required support or supported features, or both, that are associated with the operable diesel generator, results in starting the completion time for the required action. Additionally, the completion time takes into account the capacity and capability of the remaining AC sources, and the low probability of a DBA occurring during the period.

TS 3.8.1.1 Action e.

Operation may continue for a period that should not exceed 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

This level of degradation means that the offsite electrical power system does not have the capability to effect a safe shutdown and to mitigate the effects of an accident; however, the onsite AC sources have not been degraded. This level of degradation generally corresponds to a total loss of the immediately accessible offsite power sources. With both of the required'offsite circuits inoperable, sufficient onsite AC sources are available to maintain the unit in a safe shutdown condition in the event of a DBA or transient.

TS 3.8.1.1 Action f.

With two or three of the standby diesel generators inoperable, there is insufficient or no remaining standby AC sources. Thus, with an assumed loss of offsite electrical power, insufficient standby AC sources are available to power the minimum required ESF functions.

Since the offsite electrical power system is the only source of AC power for this level of degradation, the risk associated with continued operation for a very short time could be less than that associated with an immediate controlled shutdown (the immediate shutdown could cause grid instability, which could result in a total loss of AC power). Since any inadvertent generator trip could also result in a total loss of offsite AC power, however, the time allowed for continued operation is severely restricted. The intent here is to avoid the risk associated with an immediate controlled shutdown and to minimize the risk associated tith this level of degradation.

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E Attachment F Page 5 of 13 Surveillance Recuirements The AC sources are designed to permit inspection and testing of all important areas and features, especially those that have a standby function, in accordance with 10 CFR 50, Appendix A, GDC 18. Periodic component tests are supplemented by extensive functional tests during refueling outages (under simulated accident conditions). The Technical Specification Surveillance Requirements (SRs) for demonstrating the OPERABILITY of the standby diesel generators are in accordance with the recommendations of Regulatory Guide 1.108, Regulatory Guide 1.137, as addressed in the FSAR and NUREG 1431.

Where the SRs discussed herein specify voltage and frequency tolerances, the following is applicable. The minimum steady state output voltage of 3744 is 90% of the nominal 4160 V output voltage.

This value, which is specified in ANSI C84.1, allows for voltage drop to the terminals of 4000 V motors with minimum operating voltage specified as 90% or 3600 V. It also allows for voltage drops to motors and other equipment down through the 120 V level where minimum operating voltage is also usually specified as 90% of name plate rating. The specified maximum steady state output voltage of 4576 V is less than the maximum operating voltage of 4756 specified for 4000 V motors. It ensures that for a lightly loaded distribution system, the voltage at the terminals of 4000 V motors is less than the maximum rated operating voltages. The specified minimum and maximum frequencies of the standby diesel generators are 58.8 Hz and 61.2 Hz, respectively. These values are equal to plus or minus 2% of the 60 Hz nominal frequency and are derived from the recommendations given in Regulatory Guide 1.108 and NUREG 1431.

SR 4.8.1.1.1.a This SR ensures proper circuit continuity for the offsite AC electrical power supply to the onsite distribution network and availability of offsite AC electrical power. The breaker alignment verifies that each breaker is in its correct position to ensure that distribution buses and loads are connected to their preferred power source, and that appropriate independence of offsite circuits is maintained. The 7 day Frequency is adequate since breaker position is not likely to change without the operator being aware of it and because its status is displayed in the control room.

SR 4.8.1.1.1.b Transfer of each 4.16 kV ESF bus power supply from the normal offsite circ. lit to the alternate offsite circuit demonstrates the OPERABILITY of the alternate circuit distribution network to power the shutdown loads. The 18 month Frequency of the Surveillance is based on engineering judgment, taking into consideration the unit conditions required to perform the Surveillance, and is intended to be consistent with expected fuel cycle lengths. Operating experience has shown that the components usually pass the SR when performed at the 18 month TSC-94\94-319.001

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Frequency. Therefore, the Frequency was concluded to be acceptable-from a reliability standpoint.

l SR 4.8.1.1.2.a.1 1 This SR provides verification that the level of fuel oil in the fuel l tank is at or above the required level.

SR 4.8.1.1.2.a.2 This SR helps to ensure the availability of the standby electrical power supply to mitigate DBAs and transients and to maintain the unit in a safe shutdown condition.

To minimize the wear on moving parts that do not get lubricated when the engine is not running, these SRs are modified by a Note (Note 2) to indicate that all DG starts for these Surveillances may be preceded by an engine prelube period and followed by a warmup period prior to loading.

For purposes of this testing, the DGs are started from standby conditions. Standby condition for a DG mean that the diesel engine coolant and oil are being continuously circulated and temperature is being maintained consistent with manufacturer recommendations.

In order to reduce stress and wear on diesel engines, some manufactures recommend a modified start in which the starting speed of DGs is limited, warmup is limited to this lower speed, and the DGs are gradually accelerated to synchronous speed prior to loading. In addition, the modified start may involve' reduced fuel (load limit).

These start procedures are the intent of Note 3, which is only applicable when such modified start procedures are recommended by the manufacturer.

Once per 184 days the DG starts from standby conditions and achieves required voltage and frequency within 10 seconds. The 10 second start requirement supports the assumptions of the design basis LOCA analysis in the FSAR.

The 10 second start requirement is not applicable (see Note 3) when a modified start procedure as described above is used.

The normal 31 day Frequency for SR 3.8.1.2 (see Teble 4.8-1, " Diesel Generator Test Schedule, " in the accompanying LCC) is consistent with Regulatory Guide 1.108. The 184 day Frequency in Note 3 is a reduction in cold testing consistent with Generic Letter 84-15. These Frequencies provide adequate assurance of DG OPERABILITY, while minimizing degradation resulting from testing.

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Attachment F Page 7 of 13 SR 4.8.1.1.2.a.3 This Surveillance verifies that the DGs are capable of synchronizing with the offsite electrical system and accepting loads greater than or equal to the equivalent of the maximum expected accident loads. A i minimum run time of 60 minutes is required to stabilize engine l temperature, while minimizing the time that the DG is connected to the offsite source.

The load band is provided to avoid routine overloading of the DG.

Routine overloading may result in more frequent teardown inspections  :

in accordance with vendor recommendations in order to maintain DG l OPERABILITY.

This SR is modified by two Notes. Note 4 indicates that diesel engine runs for this Surveillance may include gradual loading, as recommended by the manufacturer, so that mechanical stress and wear on the diesel engine are minimized. Note 6 states that momentary transients, because of changing bus loads, do not invalidate this test.

A successful DG start under SR 4.8.1.1.2.a.2 must precede this test to credit satisfactory performance.

SR 4.8.1.1.2.b 1 Microbiological fouling is a major cause of fuel oil degradation.

There are numerous bacteria that can grow in fuel oil and cause fouling, but all must have a water environment in order to survive.

Removal of water from the fuel oil tanks once every 31 days eliminates the necessary environment for bacterial survival. This is the most effective means of controlling microbiological fouling. In addition, it eliminates the potential for water entrainment in the fuel oil during DG operation. Water may come from any of several sources, including condensation, ground water, rain water, contaminated fuel oil, and breakdown of the fuel oil by bacteria. Frequent checking for and removal of accumulated water minimizes fouling and provides data regarding the watertight integrity of the fuel oil system. The Surveillance Frequencies are established by Regulatory Guide 1.137. l This SR is for preventative maintenance. The presence of water does not necessarily represent failure of the SR, provided the accumulated water is removed during the performance of this Surveillance.

SR 4.8.1.1.2.c The requirements will be controlled and administered by the Diesel Fuel Oil Testing Program located in section 6.8.3 of Administrative l Controls. l TSC-94\94-319.001