ML101830350
| ML101830350 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 11/18/2010 |
| From: | Stewart Bailey Plant Licensing Branch II |
| To: | |
| Bailey S , NRR/DORL,415-1321 | |
| References | |
| Download: ML101830350 (8) | |
Text
AC Sources - Operating 3.8.1 ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. (continued) A.2 Declare required 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> from feature(s) with no offsite discovery of no power available offsite power to inoperable when the one sh utdown redundant required board concurrent feature(s) are inoperable. with inoperability of redundant required feature(s)
AND A.3 Restore required offsite 7 days circuit to OPERABLE status. AND 14 days from discovery of failure to meet LCO B. One required Unit 1 and 2 B.1 Verify applicable Immediately DG inoperable. compensatory actions and configuration risk AND manqgement controls are satisfied. Once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter AND BA-2 Verify power availability 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> from the offsite transmission network. AND Once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter AND (continued)
BFN-UNIT 1 3.8-2 Amendment No. ~ I
AC Sources - Operating 3.8.1 ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME B. (continued) B.~3 Declare required 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> from feature(s), supported by discovery of the inoperable Unit 1 and Condition B 2 DG, inoperable when concurrent with the redundant required inoperability of feature(s) are inoperable. redundant required feature(s)
AND B.34.1 Determine OPERABLE 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Unit 1 and 2 DG(s) are not inoperable due to common cause failure.
OR B.34.2 Perform SR 3.8.1.1 for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> OPERABLE Unit 1 and 2 DG(s).
AND B.45 Restore Unit 1 and 2 DG 7 days to OPERABLE status.
AN{)
14 days from discovery of failure to meet LCO C. Required Action B.1 and C.1 Restore required Unit 1 7 days associated Completion and 2 DG to OPERABLE Time not met. status.
(contll1ued)
BFN-UNIT 1 3.8-3 Amendment No. ~ I
AC Sources - Operating B 3.8.1 BASES ACTIONS (continued)
In order to support a 14 day Completion Time for completing planned maintenance on a Unit 1 and 2 DG the following compensatory actions and configuration risk management controls are established.
- Increased administrative control will be exercised for any hot work in the vicinity of protected equipment and in the impacted fire zones (prior to entering the period of the 14 day DG Completion Time and maintained for the duration of the 14 day DG Completion Time).
- No maintenance on fire detection or fire suppression equipment that will cause the fire detection or fire suppression equipment in the impacted fire zones to be inoperable (for the duration of the 14 day DG Completion Time).
- Transient combustible loading in the impacted fire zones will be reviewed and any unnecessary transient combustibles will be removed (prior to entering the period of the 14 day DG Completion Time and maintained for the duration of the 14 day DG Completion Time).
- Only one of the eight DGs will be taken out of service.
Maintenance on more than one DG will not be permitted during the 14 day DG Completion Time.
- Electrical boards or transformers will not be removed from service for maintenance activities during the 14 day DG Completion Time.
(continued)
BFN-UNIT 1 B 3.8-14a Revision Q
AC Sources - Operating 83.8.1 8ASES ACTIONS 8.1 (continued)
- Weather conditions will be evaluated prior to entering the 14 day DG Completion Time for planned maintenance. A 14 day DG Completion Time will not be entered for planned maintenance purposes if official weather forecasts are predicting severe conditions (tornado or thunderstorm warnings).
- Maintenance will not be performed in the switchyard that would challenge offsite power availability during the 14 day DG Completion Time.
- The condition of the offsite power supply and switchyard will be evaluated prior to entering the 14 day DG Completion Time for planned maintenance. TVA procedures exist to determine acceptable grid conditions for entering the 14 day DG Completion Time to perform planned maintenance.
- The system dispatcher will be contacted once per day and informed of the DG status along with the power needs of the facility during the 14 day DG Completion Time.
- The Unit 1 and Unit 2 HPCI pumps, RCIC pumps, and RHR pumps will not be removed from service for maintenance activities during the 14 day DG Completion Time for Unit 1 and Unit 2 DGs.
When a DG is inoperable, it is necessary to verify the applicable compensatory actions and configuration risk management controls are satisfied immediately and once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. The Completion Time of "Immediately" reflects the fact that in order to ensure that the full 14 day Completion Time of Required Action 8.5 is available for completing planned maintenance of a Unit 1 and 2 DG, prudent plant practice (continued) 8FN-UNIT 1 83.8-14b Revision Q
AC Sources - Operating B 3.8.1 BASES ACTIONS 8.1 (continued)
(continued) dictates that the applicable compensatory actions and configuration risk management controls be verified to be satisfied prior to making a DG inoperable for planned maintenance. If Required Action 8.1 is not met or the status of the applicable compensatory actions and configuration risk management controls changes from "satisfied" to "not satisfied" after Required Action B.1 is initially met, Condition C must be immediately entered.
To ensure a highly reliable power source remains with one Unit 1 and 2 DG inoperable, it is necessary to verify the availability of the required offsite circuits on a more frequent basis. This action ensures proper circuit continuity for the offsite AC electrical power supply to the onsite distribution network and availability of offsite AC electrical power. However, if an offsite circuit is 110t available, the offsite circuit is inoperable, and additional Conditions must then be entered.
Required Action B.~3 is intended to provide assurance that a loss of offsite power, during the period that a Unit 1 and 2 DG is inoperable, does not result in a complete loss of safety function of critical systems. These features are designed with redundant safety related divisions (Le., single division systems are not included). Redundant required features failures consist of inoperable features associated with a division redundant to the division that has an inoperable Unit 1 and 2 DG. For example, if DG A was inoperable and RHR pump D was inoperable for maintenance, then RHR pump A would have to be declared inoperable.
The Completion Time is intended to allow the operator time to evaluate and repair any discovered inoperabilities. This (continued)
BFN-UNIT 1 B 3.8-15 Revision Q
AC Sources - Operating B 3.8.1 BASES ACTIONS (continued)
Based on the diversity of AC electrical power sources, aOO--the remaining redundancy and reliability, and the applicable compensatory actions and configuration risk management controls, operation may continue in Condition B for a period that should not exceed 1-14 days from discovery of failure to meet the LCO. In Condition B, the remaining OPERABLE DGs and offsite circuits are adequate to supply electrical power to the onsite Class 1E Distribution System. The 1-14 day from discovery of failure to meet the LCO Completion Time is based on a plant-specific risk assessment and also takes into account the capacity and capability of tile remaining AC sources, reasonable time for repairs, and low probability of a DBA occurring during this period.
The seoond Completion Time for Required Action B.4-5 also establishes a limit on the maximum time allowed for any combination of required AC power sources to be inoperable during any single contiguous occurrence of failing to meet the LCO. If Condition B is entered while, for instance, an offsite circuit is inoperable and that circuit is subsequently restored OPERABLE, the LCO may already have been not met for up to 7 days. This situation could lead to a total time in excess of 14 days, since initial failure to meet the LCO, to restore the DG.
At this time, an offsite circuit could again become inoperable, the DG restored OPERABLE, and an additional 7 days (for a total of 21 days) allowed prior to complete restoration of the LCO. The 14 day Completion Time provides a limit on the time allowed in a specified condition after discovery of failure to meet the LCO. This limit is considered reasonable for situations in which Conditions A and B are entered concurrently. The "Llli..Q" connector between the 7 day and 14 day Completion Times means that both Completion Times apply simultaneously, and the more restrictive must be metwould also limit the maximum time a DG is inoperable if the status of the applicable compensatory actions and configuration risk management controls changes from being satisfied to not being satisfied (this is discussed in the Required Action C.1 Bases discussion).
(continued)
BFN-UNIT 1 B 3.8-18 Revision Q
AC Sources - Operating B 3.8.1 BASES ACTIONS B.5 (continued)
As in Required Action 8.23, the Completion Time allows for an exception to the normal "time zero" for beginning the allowed outage time "clock." This exception results in establishing the "time zero" at the time that the LCO was initially not met, instead of the time that Condition B was entered.
The extended Completion Time for restoration of an inoperable DG afforded by the applicable compensatory actions and configuration risk management controls is intended to allow completion of a DG overhaul and modifications; however, subject to the DG reliability program (e.g., maintaining minimum DG reliability of 0.95 per demand for each DG), INPO performance criteria, and good operating practices, using the extended Completion Time is permitted for other reasons.
If the applicable compensatory actions and configuration risk management controls are not verified to be satisfied with the Completion Time of Required Action B.1, or if the status of the applicable compensatory actions and configuration risk management controls changes after Required Action B.1 is initially met, the DG must be restored to OPERABLE status within 7 days. The 7 day Completion Time begins upon entry into Condition C (i.e., upon discovery of failure to meet Required Action B.1). However, the total time to restore an inoperable DG cannot exceed 14 days (per the Completion Time of Required Action B.5).
The diversity of AC electrical power sources is sufficient to allow operation to continue in Condition C for a period that should not exceed 7 days, if the applicable compensatory actions and configuration risk management controls are not satisfied (refer to Required Action B.1 Bases discussion). In Condition C, the remaining OPERABLE DGs and offsite circuits are adequate to (continued)
BFN-UNIT 1 B3.8-18a Revision Q
AC Sources - Operating B 3.8.1 BASES ACTIONS C.1 (continued)
(continued) supply electrical power to the onsite Class 1E Distribution System. The 7 day Completion Time takes into account the redundancy, capacity, and capability of the remaining AC sources, reasonable time for repairs, and low probability of a DBA occurring during this period.
GD.1 With one division of Unit 1 and 2 480 V load shed logic inoperable, the reliability of the DGs is degraded, and the potential for the loss of all four Unit 1 and 2 DGs is increased with attendant potential challenge to plant safety systems. In this condition, however, the remaining division of Unit 1 and 2 480 V load shed logic is capable of performing its intended function of limiting the loads on the Unit 1 and 2 DGs.
The 7 day Completion Time takes into account the capability of the remaining division of Unit 1 and 2 480 V load shed logic, reasonable time for repairs, and the low probability of a DBA occurring during this period.
QE.1 With one division of common accident signal logic inoperable (including the DG breaker unit priority re-trip function and the CS and LPCI preferred pump logic function described in Bases Section B 3.8.1), the plant electrical system response is degraded, and the potential for inappropriate electrical system alignment is increased with attendant potential challenge to plant safety systems. In this condition, however, the remaining division of common accident signal logic is capable of performing its intended function of providing a start signal to the Unit 1 and 2 DGs during a DBA.
The 7 day Completion Time takes into account the capability of the remaining division of common accident signal logic, reasonable time for repairs, and the low probability of a DBA occurring during this period.
(continued)
BFN-UNIT 1 B 3.8-19 Revision-Q.,47 March 22, 2007