ML14342A191
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McGuire Units 1 and 2 B 3.8.3-1 Revision No. 123 Diesel Fuel Oil and Starting Air B 3.8.3 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.3 Diesel Fuel Oil and Starting Air BASES BACKGROUND Each diesel generator (DG) is provided with a storage tank having a fuel oil capacity sufficient to operate that diesel for a period of 5 days while the DG is supplying maximum post loss of coolant accident load demand discussed in the UFSAR, Section 8.3.1.1.7 (Ref. 1). The maximum load demand is calculated using the assumption that a minimum of any two DGs is available. This onsite fuel oil capacity is sufficient to operate the DGs for longer than the time to replenish the onsite supply from outside sources.
Fuel oil is transferred from storage tank to day tank by either of two transfer pumps associated with each storage tank. Redundancy of pumps and piping precludes the failure of one pump, or the rupture of any pipe, valve or tank to result in the loss of more than one DG. All outside tanks, pumps, and piping are located underground.
For proper operation of the standby DGs, it is necessary to ensure the proper quality of the fuel oil. Regulatory Guide 1.137 (Ref. 2) addresses the recommended fuel oil practices as supplemented by ANSI N195 (Ref. 3). The fuel oil properties governed by these SRs are the water and sediment content, the kinematic viscosity, specific gravity (or API gravity),
and impurity level.
Each DG has an air start system with adequate capacity for five successive starts on the DG without recharging the air start receiver(s).
APPLICABLE The initial conditions of Design Basis Accident (DBA) and transient SAFETY ANALYSES analyses in the UFSAR, Chapter 6 (Ref. 4), and in the UFSAR, Chapter 15 (Ref. 5), assume Engineered Safety Feature (ESF) systems are OPERABLE. The DGs are designed to provide sufficient capacity, capability, redundancy, and reliability to ensure the availability of necessary power to ESF systems so that fuel, Reactor Coolant System and containment design limits are not exceeded. These limits are discussed in more detail in the Bases for Section 3.2, Power Distribution Limits; Section 3.4, Reactor Coolant System (RCS); and Section 3.6, Containment Systems.
Since diesel fuel oil and the air start subsystem support the operation of the standby AC power sources, they satisfy Criterion 3 of 10 CFR 50.36 (Rev. 6).
Diesel Fuel Oil and Starting Air B 3.8.3 BASES McGuire Units 1 and 2 B 3.8.3-2 Revision No. 123 LCO Stored diesel fuel oil is required to have sufficient supply for 5 days of full load operation. It is also required to meet specific standards for quality.
DG day tank fuel requirements, as well as transfer capability from the storage tank to the day tank, are addressed in LCO 3.8.1, "AC Sources Operating," and LCO 3.8.2, "AC SourcesShutdown." This requirement, in conjunction with an ability to obtain replacement supplies within 4 days, supports the availability of DGs required to shut down the reactor and to maintain it in a safe condition for an anticipated operational occurrence (AOO) or a postulated DBA with loss of offsite power.
The starting air system is required to have a minimum capacity for 5 successive DG starts without recharging the air start receivers.
APPLICABILITY The AC sources (LCO 3.8.1 and LCO 3.8.2) are required to ensure the availability of the required power to shut down the reactor and maintain it in a safe shutdown condition after an AOO or a postulated DBA. Since stored diesel fuel oil and the starting air subsystem support LCO 3.8.1 and LCO 3.8.2, stored diesel fuel oil and starting air are required to be within limits when the associated DG is required to be OPERABLE.
ACTIONS The ACTIONS Table is modified by a Note indicating that separate Condition entry is allowed for each DG. This is acceptable, since the Required Actions for each Condition provide appropriate compensatory actions for each inoperable DG subsystem. Complying with the Required Actions for one inoperable DG subsystem may allow for continued operation, and subsequent inoperable DG subsystem(s) are governed by separate Condition entry and application of associated Required Actions.
A.1 In this Condition, the 5 day fuel oil supply for a DG is not available.
However, the Condition is restricted to fuel oil level reductions that maintain at least a 4 day supply. These circumstances may be caused by events, such as full load operation required after an inadvertent start while at minimum required level, or feed and bleed operations, which may be necessitated by increasing particulate levels or any number of other oil quality degradations. This restriction allows sufficient time for obtaining the requisite replacement volume and performing the analyses required prior to addition of fuel oil to the tank. A period of 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> is considered sufficient to complete restoration of the required level prior to declaring the DG inoperable. This period is acceptable based on the remaining capacity (> 4 days), the fact that procedures will be initiated to obtain replenishment, and the low probability of an event during this brief period.
Diesel Fuel Oil and Starting Air B 3.8.3 BASES McGuire Units 1 and 2 B 3.8.3-3 Revision No. 123 ACTIONS (continued)
B.1 This Condition is entered as a result of a failure to meet the acceptance criterion of SR 3.8.3.2. Normally, trending of particulate levels allows sufficient time to correct high particulate levels prior to reaching the limit of acceptability. Poor sample procedures (bottom sampling),
contaminated sampling equipment, and errors in laboratory analysis can produce failures that do not follow a trend. Since the presence of particulates does not mean failure of the fuel oil to burn properly in the diesel engine, and particulate concentration is unlikely to change significantly between Surveillance Frequency intervals, and proper engine performance has been recently demonstrated (within 31 days), it is prudent to allow a brief period prior to declaring the associated DG inoperable. The 7 day Completion Time allows for further evaluation, resampling and re-analysis of the DG fuel oil.
C.1 With the new fuel oil properties defined in the Bases for SR 3.8.3.2 not within the required limits, a period of 30 days is allowed for restoring the stored fuel oil properties. This period provides sufficient time to test the stored fuel oil to determine that the new fuel oil, when mixed with previously stored fuel oil, remains acceptable, or to restore the stored fuel oil properties. This restoration may involve feed and bleed procedures, filtering, or combinations of these procedures. Even if a DG start and load was required during this time interval and the fuel oil properties were outside limits, there is a high likelihood that the DG would still be capable of performing its intended function.
D.1 DG starting air system normal alignment allows air from both receivers to enter both left and right starting air headers. When one receiver is isolated, both left and right starting air headers are supplied from the remaining receiver. With the degraded receiver isolated and the remaining receiver > 210 psig, the capacity for five starts exists and entry into Condition D is not required. Therefore, Condition D is modified by a Note that states that a single air receiver may be isolated without entering Condition D. Each DG is fully OPERABLE whenever a single starting air receiver is pressurized > 210 psig and is capable of performing its necessary and related support function. A single DG receiver pressurized to > 210 psig has sufficient air capacity for five successive DG starts; therefore, entering Condition D when one receiver is isolated is not required.
Diesel Fuel Oil and Starting Air B 3.8.3 BASES McGuire Units 1 and 2 B 3.8.3-4 Revision No. 123 When a DG starting air receiver is isolated, the redundant DG starting air receiver maintains DG OPERABILITY. With starting air receiver pressure
< 210 psig, sufficient capacity for five successive DG starts does not exist. However, as long as the receiver pressure is > 125 psig, there is adequate capacity for at least one start, and the DG can be considered OPERABLE while the starting air receiver pressure is restored to the required limit. A period of 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> is considered sufficient to complete restoration to the required pressure prior to declaring the DG inoperable.
This period is acceptable based on the remaining air start capacity, the fact that most DG starts are accomplished on the first attempt, and the low probability of an event during this brief period. Condition E is required whenever the remaining DG starting air receiver is not restored within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or cannot be restored within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.
Prior to manually isolating a degraded receiver and upon receiving a diesel start signal, part of the starting air is lost to pressurizing the degraded receiver. With either starting air receiver pressure < 210 psig and > 125 psig, Condition D applies until the degraded receiver is isolated. Therefore, alarm response procedures ensure this period is minimized and actions are taken to isolate the degraded receiver. With the degraded starting air receiver isolated and the remaining receiver pressure > 210 psig, the capacity for five starts exists and the DG can be considered OPERABLE while the repairs necessary to restore the degraded receiver are completed.
E.1 With a Required Action and associated Completion Time not met, or one or more DG's fuel oil or starting air subsystem not within limits for reasons other than addressed by Conditions A through D, the associated DG may be incapable of performing its intended function and must be immediately declared inoperable.
Diesel Fuel Oil and Starting Air B 3.8.3 BASES McGuire Units 1 and 2 B 3.8.3-5 Revision No. 123 SURVEILLANCE SR 3.8.3.1 REQUIREMENTS This SR provides verification that there is an adequate inventory of fuel oil in the storage tanks to support each DG's operation for 5 days at full load.
The 4 day period is sufficient time to place the unit in a safe shutdown condition and to bring in replenishment fuel from an offsite location.
The Surveillance Frequency is based on operating experience, equipment reliability, and plant risk and is controlled under the Surveillance Frequency Control Program.
SR 3.8.3.2 The tests listed below are a means of determining whether new fuel oil is of the appropriate grade and has not been contaminated with substances that would have an immediate, detrimental impact on diesel engine combustion. If results from these tests are within acceptable limits, the fuel oil may be added to the storage tanks without concern for contaminating the entire volume of fuel oil in the storage tanks. These tests are to be conducted prior to adding the new fuel to the storage tank(s). The tests, limits, and applicable ASTM Standards are as follows:
- a.
Sample the new fuel oil in accordance with ASTM D4057 (Ref. 7);
- b.
Verify in accordance with the tests specified in ASTM D975 that the sample has a kinematic viscosity at 40°C of 1.9 centistokes and 4.1 centistokes, and a flash point of 125°F; and
- c.
Verify that the new fuel oil has a clear and bright appearance with proper color when tested in accordance with ASTM D4176 (Ref. 7) or a water and sediment content within limits when tested in accordance with ASTM D2709 (Ref. 7); and
- d.
Verify that the new fuel oil has an absolute specific gravity at 60 /
60oF of > 0.83 and < 0.89 when tested in accordance with ASTM D1298 or an API gravity at 60oF of > 27o and < 39o when tested in accordance with ASTM D287 (Ref.7).
Diesel Fuel Oil and Starting Air B 3.8.3 BASES McGuire Units 1 and 2 B 3.8.3-6 Revision No. 123 SURVEILLANCE REQUIREMENTS (continued)
Failure to meet any of the above limits, except for clear and bright, is cause for rejecting the fuel oil, but does not represent a failure to meet the LCO concern since the fuel oil is not added to the storage tanks. If the fuel oil fails on clear and bright, it may be accepted if it passes water and sediment. The specifications for water and sediment recognize that a small amount of water and sediment is acceptable. Thus, this test may be used after a clear and bright test to provide a more quantitative result.
Within 31 days following the initial new fuel oil sample, the fuel oil is analyzed to establish that the other properties specified in Table 1 of ASTM D975 (Ref. 7) are met for new fuel oil when tested in accordance with ASTM D975 (Ref. 7), except that the analysis for sulfur may be performed in accordance with ASTM D5453 (Ref. 7), D3120 (Ref. 7) or ASTM D2622 (Ref. 7). The 31 day period is acceptable because the fuel oil properties of interest, even if they were not within stated limits, would not have an immediate effect on DG operation. This Surveillance ensures the availability of high quality fuel oil for the DGs.
Fuel oil degradation during long term storage shows up as an increase in particulate, due mostly to oxidation. The presence of particulate does not mean the fuel oil will not burn properly in a diesel engine. The particulate can cause fouling of filters and fuel oil injection equipment, however, which can cause engine failure.
Particulate concentrations should be determined based on ASTM D6217 (Ref. 7). This test method is used for assessing the mass quantity of particulates in middle distillate fuels, which includes 2-D diesel fuel. This method involves a gravimetric determination of total particulate concentration in the fuel oil and has a limit of 10 mg/l. For those designs in which the total stored fuel oil volume is contained in two or more interconnected tanks, each tank must be considered and tested separately.
The Frequency of this test takes into consideration fuel oil degradation trends that indicate that particulate concentration is unlikely to change significantly between Frequency intervals.
Diesel Fuel Oil and Starting Air B 3.8.3 BASES McGuire Units 1 and 2 B 3.8.3-7 Revision No. 123 SURVEILLANCE REQUIREMENTS (continued)
SR 3.8.3.3 This Surveillance ensures that, without the aid of the refill compressor, sufficient air start capacity for each DG is available. The system design requirements provide for a minimum of five engine start cycles without recharging. A start cycle is defined as the period of time required to reach 95% speed from standby prelubed condition. The pressure specified in this SR is intended to reflect a conservative value at which a single fast start and five total starts can be accomplished.
The Surveillance Frequency is based on operating experience, equipment reliability, and plant risk and is controlled under the Surveillance Frequency Control Program.
SR 3.8.3.4 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 storage tanks 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, and contaminated fuel oil, and from 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 Frequency is based on operating experience, equipment reliability, and plant risk and is controlled under the Surveillance Frequency Control Program. This SR is for preventive maintenance. The presence of water does not necessarily represent failure of this SR, provided the accumulated water is removed during performance of the Surveillance.
Diesel Fuel Oil and Starting Air B 3.8.3 BASES McGuire Units 1 and 2 B 3.8.3-8 Revision No. 123 REFERENCES
- 1.
UFSAR, Section 8.3.1.1.7.
- 2.
- 3.
ANSI N195-1976, Appendix B.
- 4.
UFSAR, Chapter 6.
- 5.
UFSAR, Chapter 15.
- 6.
10 CFR 50.36, Technical Specifications, (c)(2)(ii).
- 7.
ASTM Standards: D4057; D975; D1298; D4176; D2709; D6217; D2622; D287; D5453; and D3120.
- 8.
UFSAR, Section 18.2.4, Chemistry Control Program.
- 9.
McGuire License Renewal Commitments MCS-1274.00-00-0016, Section 4.6, Chemistry Control Program.