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| number = ML082670543 | | number = ML082670543 | ||
| issue date = 09/18/2008 | | issue date = 09/18/2008 | ||
| title = | | title = Technical Specification (TS) Change No. 08-07, Auxiliary Feedwater Auto-Start Upon Trip of the Turbine Driven Main Feedwater Pumps | ||
| author name = Brandon M | | author name = Brandon M | ||
| author affiliation = Tennessee Valley Authority | | author affiliation = Tennessee Valley Authority | ||
| addressee name = | | addressee name = | ||
Line 16: | Line 16: | ||
=Text= | =Text= | ||
{{#Wiki_filter:Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 September 18, 2008 WBN-TS-08-07 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Gentlemen: | {{#Wiki_filter:Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 September 18, 2008 WBN-TS-08-07 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Gentlemen: | ||
In the Matter of ) Docket No.50-390 Tennessee Valley Authority | In the Matter of ) Docket No.50-390 Tennessee Valley Authority ) | ||
WATTS BAR NUCLEAR PLANT (WBN) UNIT 1 - TECHNICAL SPECIFICATION (TS) | |||
CHANGE NO. 08-07, AUXILIARY FEEDWATER AUTO-START UPON TRIP OF THE TURBINE DRIVEN MAIN FEEDWATER PUMPS The U.S. Nuclear Regulatory Commission (NRC) recently issued Inspection Report 2008-003, dated August 7, 2008, to Watts Bar Nuclear (WBN) Plant. In this report, NRC informed the Tennessee Valley Authority (TVA) that plant operation is not conforming to TS 3.3,2 Function 6.e when a non-operating turbine driven main feedwater (TDMFW) pump is reset and entering Mode 2. TVA had previously considered the associated auxiliary feedwater (AFW) auto-start channel operable; however, NRC informed TVA that a non-operating TDMFW pump in the reset condition impacts operability of the AFW auto-start channel due to the invalid indication of the TDMFW pump status. | |||
Therefore, pursuant to 10 CFR 50.90, TVA is submitting a request for a TS change (TS-08-07) to license NPF-90 for WBN Unit 1. The proposed TS change will modify Mode 1 and 2 Applicability for Function 6.e of TS Table 3.3.2-1, "Engineered Safety Feature Actuation System Instrumentation." This safety function is associated with AFW automatic start on Trip of all Main Feedwater Pumps. In addition, the proposed change will also revise limiting condition for operation (LCO) 3.3.2, Condition J, to be consistent with WBN Unit 1 design bases. | |||
Function 6.e of TS Table 3.3.2-1 is an anticipatory function that provides early actuation of the AFW system but is not required by the accident analysis for WBN. Current TS requires that this function be operable in Mode 2 prior to the availability of sufficient | |||
'feedwater demand to run a TDMFW pump. | 'feedwater demand to run a TDMFW pump. | ||
U.S. Nuclear Regulatory Commission Page 2 September 1 8, 2008 | |||
Additionally, in accordance with 10 CFR 50.91 (b)(1), TVA is sending a copy of this letter and attachments to the Tennessee State Department of Public Health. | U.S. Nuclear Regulatory Commission Page 2 September 1 8, 2008 to this letter provides the description and evaluation of the proposed TS change. TVA has determined that the proposed change does not involve a significant hazards consideration, and the TS change qualifies for a categorical exclusion from environmental review pursuant to the provisions of 10 CFR 51.22(c)(9). Additionally, in accordance with 10 CFR 50.91 (b)(1), TVA is sending a copy of this letter and attachments to the Tennessee State Department of Public Health. contains copies of the appropriate TS pages marked-up to show the proposed change. | ||
If you have any questions about this change, please contact R. L. Clark at (423) 365-1818 or me at (423) 365-1824.I declare under penalty of perjury that the foregoing is true and correct. Executed on this 18th day of September, 2008.Sincerely, M. K. Brandon | TVA requests approval of this amendment, as soon as practical, but not later than September 1, 2009 to support restart from the Cycle 9 refueling outage. TVA requests a 45 day implementation period for the approved TS change. | ||
There are no commitments associated with this submittal. | |||
If you have any questions about this change, please contact R. L. Clark at (423) 365-1818 or me at (423) 365-1824. | |||
I declare under penalty of perjury that the foregoing is true and correct. Executed on this 18th day of September, 2008. | |||
Sincerely, M. K. Brandon | |||
==Enclosures:== | ==Enclosures:== | ||
: 1. TVA Evaluation of Proposed Technical Specifications Change 2. Proposed Technical Specifications Change (Mark-Up)cc: See page 3 U.S. Nuclear Regulatory Commission Page 3 September 18, 2008 Enclosures cc (Enclosures 1-2): NRC Resident Inspector Watts Bar Nuclear Plant 1260 Nuclear Plant Road Spring City, Tennessee 37381 ATTN: Patrick D. Milano, Project Manager U.S. Nuclear Regulatory Commission Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation MS 08H4 Washington, DC 20555-0001 U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 Mr. Lawrence E. Nanny, Director Division of Radiological Health 3 d Floor L & C Annex 401 Church Street Nashville, Tennessee 37243 ENCLOSURE1 TENNESSEE VALLEY AUTHORITY (TVA)WATTS BAR NUCLEAR PLANT (WBN)UNIT 1 TVA EVALUATION OF PROPOSED CHANGE 1.0 | : 1. TVA Evaluation of Proposed Technical Specifications Change | ||
: 2. Proposed Technical Specifications Change (Mark-Up) cc: See page 3 | |||
U.S. Nuclear Regulatory Commission Page 3 September 18, 2008 Enclosures cc (Enclosures 1-2): | |||
NRC Resident Inspector Watts Bar Nuclear Plant 1260 Nuclear Plant Road Spring City, Tennessee 37381 ATTN: Patrick D. Milano, Project Manager U.S. Nuclear Regulatory Commission Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation MS 08H4 Washington, DC 20555-0001 U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 Mr. Lawrence E. Nanny, Director Division of Radiological Health 3 d Floor L & C Annex 401 Church Street Nashville, Tennessee 37243 | |||
ENCLOSURE1 TENNESSEE VALLEY AUTHORITY (TVA) | |||
WATTS BAR NUCLEAR PLANT (WBN) | |||
UNIT 1 TVA EVALUATION OF PROPOSED CHANGE 1.0 | |||
==SUMMARY== | ==SUMMARY== | ||
DESCRIPTION This evaluation supports a request to amend Operating License NPF-90 for WBN Unit 1. The proposed TS change will modify Mode 1 and 2 Applicability for Function 6.e of Table 3.3.2-1,"Engineered Safety Feature Actuation System Instrumentation." This safety function is associated with the automatic start of the auxiliary feedwater (AFW) system upon Trip of all Main Feedwater (MFW) Pumps. In addition, the proposed change will also revise limiting condition for operation (LCO) 3.3.2, Condition J, to be consistent with WBN Unit 1 design bases.On August 7, 2008, the NRC issued, Watts Bar Nuclear Plant -Inspection Report 2008-003. | DESCRIPTION This evaluation supports a request to amend Operating License NPF-90 for WBN Unit 1. The proposed TS change will modify Mode 1 and 2 Applicability for Function 6.e of Table 3.3.2-1, "Engineered Safety Feature Actuation System Instrumentation." This safety function is associated with the automatic start of the auxiliary feedwater (AFW) system upon Trip of all Main Feedwater (MFW) Pumps. In addition, the proposed change will also revise limiting condition for operation (LCO) 3.3.2, Condition J, to be consistent with WBN Unit 1 design bases. | ||
In this report, the NRC informed TVA that plant operation did not conform to TS 3.3.2 Function 6.e when a non-operating TDMFW pump is reset and entering Mode 2. TVA had previously considered the associated AFW auto-start channel operable; however, NRC informed TVA that a non-operating TDMFW pump in the reset condition impacts operability of the AFW auto-start channel due to the false (i.e., invalid) indication of the TDMFW pump status. This change will permanently address this startup and shutdown issue.For WBN Unit 1 to comply with the current TS for entry into Mode 2, each TDMFW pump would need to be in a tripped condition. | On August 7, 2008, the NRC issued, Watts Bar Nuclear Plant - Inspection Report 2008-003. In this report, the NRC informed TVA that plant operation did not conform to TS 3.3.2 Function 6.e when a non-operating TDMFW pump is reset and entering Mode 2. TVA had previously considered the associated AFW auto-start channel operable; however, NRC informed TVA that a non-operating TDMFW pump in the reset condition impacts operability of the AFW auto-start channel due to the false (i.e., invalid) indication of the TDMFW pump status. This change will permanently address this startup and shutdown issue. | ||
This configuration would result in an auto-start of the motor driven and turbine driven AFW pumps. The presence of such an automatic AFW system start signal at this point in the plant startup sequence (Mode 3 to Mode 2) is an unnecessary burden on the operators because the steam generator (SG) demand for feedwater is too low to require operation of all three AFW pumps.2.0 DETAILED DESCRIPTION The AFW auto-start function on Trip of all MFW Pumps is an anticipatory function in that it provides early actuation of the AFW system to mitigate the consequences of a loss of normal feedwater which is a Condition II Fault. The current TS requires that this function be operable in Mode 2 prior to the availability of sufficient feedwater demand to run a TDMFW pump.The proposed TS change will: (1) Modify Function 6.e of TS Table 3.3.2-1 to read: 'Trip of all Turbine Driven Main Feedwater Pumps." (2) Modify LCO 3.3.2, Condition J to read: "One or more Turbine Driven Main Feedwater Pump trip channel(s) inoperable." (3) Modify LCO 3.3.2, Required Action J. 1 to read: El -1 "Restore channel(s) to OPERABLE status." (4) Add the following footnote to Mode 1 Applicability for Function 6.e of TS Table 3.3.2-1: "Entry into Condition J may be suspended for up to 4 hours when placing the second turbine driven main feedwater (TDMFW) pump in service or removing one of two TDMFW pumps from service." (5) Add the following footnote to Mode 2 Applicability for Function 6.e of TS Table 3.3.2-1: 'When one or more Turbine Driven Feedwater Pump(s) are supplying feedwater to steam generators." The proposed TS changes listed above are necessary to resolve the compliance issue NRC brought to TVA's attention. | For WBN Unit 1 to comply with the current TS for entry into Mode 2, each TDMFW pump would need to be in a tripped condition. This configuration would result in an auto-start of the motor driven and turbine driven AFW pumps. The presence of such an automatic AFW system start signal at this point in the plant startup sequence (Mode 3 to Mode 2) is an unnecessary burden on the operators because the steam generator (SG) demand for feedwater is too low to require operation of all three AFW pumps. | ||
2.0 DETAILED DESCRIPTION The AFW auto-start function on Trip of all MFW Pumps is an anticipatory function in that it provides early actuation of the AFW system to mitigate the consequences of a loss of normal feedwater which is a Condition II Fault. The current TS requires that this function be operable in Mode 2 prior to the availability of sufficient feedwater demand to run a TDMFW pump. | |||
The proposed TS change will: | |||
(1) Modify Function 6.e of TS Table 3.3.2-1 to read: | |||
'Trip of all Turbine Driven Main Feedwater Pumps." | |||
(2) Modify LCO 3.3.2, Condition J to read: | |||
"One or more Turbine Driven Main Feedwater Pump trip channel(s) inoperable." | |||
(3) Modify LCO 3.3.2, Required Action J. 1 to read: | |||
El -1 | |||
"Restore channel(s) to OPERABLE status." | |||
(4) Add the following footnote to Mode 1 Applicability for Function 6.e of TS Table 3.3.2-1: | |||
"Entry into Condition J may be suspended for up to 4 hours when placing the second turbine driven main feedwater (TDMFW) pump in service or removing one of two TDMFW pumps from service." | |||
(5) Add the following footnote to Mode 2 Applicability for Function 6.e of TS Table 3.3.2-1: | |||
'When one or more Turbine Driven Feedwater Pump(s) are supplying feedwater to steam generators." | |||
The proposed TS changes listed above are necessary to resolve the compliance issue NRC brought to TVA's attention. | |||
==3.0 BACKGROUND== | |||
The condensate and feedwater systems are designed to provide feedwater to the SG secondary side during normal plant operating conditions and to guarantee that feedwater will not be delivered to the SGs when feedwater isolation is required. The systems are designed to take suction from the main condenser hotwell and deliver feed flow to the SGs at elevated temperature and pressure. These systems consist of many components including 3 hotwell pumps, 3 condensate booster pumps, 2 TDMFW pumps and one standby motor driven (SBMFW) pump along with high and low pressure feedwater heaters, demineralizers and other major equipment needed to process feed flow. Additional information can be found in Updated Final Safety Analysis Report (UFSAR) Section 10.4.7, "Condensate and Feedwater System." | |||
The SBMFW pump was originally designed to provide feed flow during startup and shutdown conditions below 15% rated thermal power (RTP) and to accommodate loss of one TDMFW pump above 67% RTP. Due to the non-compliance issues addressed in NRC Inspection Reports 2006-004 and 2008-003, the AFW motor driven pumps and the TDMFW pumps will be used for normal plant startup and shutdown in compliance with this proposed change. | |||
Each TDMFW pump is equipped with one oil pressure switch located in the turbine's hydraulic control circuit which makes up one channel of the AFW auto-start circuit. A low pressure signal from this pressure switch indicates a trip of that pump, and a trip of both TDMFW pumps will automatically start the motor driven and turbine driven AFW pumps. Currently, LCO 3.3.2, Function 6.e, requires that automatic start of the AFW pumps be operable during Mode 2 even when no TDMFW pumps are in operation. | |||
The AFW auto-start channel for each TDMFW pump is "reset" when the TDMFW pump's electrical control circuit is energized and the pressure switch located in the turbine's hydraulic control circuit senses that the circuit is pressurized (> 50 psig). The TDMFW pump is considered to be in service when the pump is providing feed flow to the SGs. The AFW auto-start channel is in the "trip" condition when the TDMFW pump's electrical control circuit is energized and the hydraulic control circuit is depressurized (< 50 psig). The TDMFW pump is considered to be out of service when the pump is not providing feed flow to the SGs. Because the anticipatory AFW system actuation circuits are designed "energize-to-actuate", the AFW auto-start channel is in the "bypass" condition whenever the TDMFW pump's electrical control circuit is de-energized regardless if the hydraulic control circuit is pressurized or not (see Fig. 1). | |||
El -2 | |||
When entering Mode 2, the AFW system is placed into service to control and maintain SG level. | |||
Between 2% and 4% RTP, a TDMFW pump is "reset", as described above, and placed into service. During the process of placing one TDMFW pump in service, the electrical control circuit for the non-operating TDMFW pump is de-energized which places its associated AFW auto-start channel in the "bypass" condition. This action is necessary to prevent inadvertent AFW system actuation during rollup trip testing and overspeed trip testing of the operating TDMFW pump. | |||
Once the operating TDMFW pump has established sufficient feed flow to maintain SG level, the electrical control circuit for the non-operating TDMFW pump is re-energized, and its associated AFW auto-start channel is placed in the '"trip" condition. During this time the main feedwater system is in service and the AFW pumps are taken out of service. Under these conditions the AFW auto start circuit will be in a half trip condition (one-out-of-two) in Mode 2 and during the transition from Mode 2 to Mode 1. If the operating TDMFW pump were to trip during this period, an AFW auto-start signal would be generated causing all three AFW pumps to start. | |||
After entering Mode 1 the second TDMFW pump is reset and placed into service (approximately 50% RTP). This process requires less than 4 hours to complete. During this process, the second TDMFW pump is placed on turning gear, the auxiliary support systems such as injection water, gland steam sealing, steam drains, raw cooling water, and lube oil are aligned and placed into operation. Afterwards, the main feed pump (MFP) turbine vacuum is established, the turbine rolled, and the MFP temperature increased to normal operating levels. With both TDMFW pumps in service and both AFW auto-start channels in "reset", the AFW auto-start function is fully operational. | |||
During plant shutdown, the sequence of events is reversed. At a prescribed power level above 50% RTP, one TDMFW pump is removed from service and is placed in the tripped condition. | |||
==4.0 TECHNICAL ANALYSIS== | |||
The proposed TS change to revise LCO 3.3.2, Condition J, Required Action J.1, and Function 6.e of TS Table 3.3.2-1 are given below. | |||
4.1 Proposed Change to Function 6.e of Table 3.3.2-1 The proposed change will revise Function 6.e of Table 3.3.2-1 to read: | |||
"Trip of all Turbine Driven Main Feedwater Pumps" This change is necessary to clarify that this trip function is only applicable to the TDMFW pumps and not the SBMFW pump. This change is administrative in nature. It does not alter any TS requirements or operational restrictions and therefore does not affect plant safety. | |||
4.2 Proposed Change to LCO 3.3.2, Condition J The proposed change will revise LCO 3.3.2, Condition J to read: | |||
"One or more Turbine Driven Main Feedwater Pump trip channel(s) inoperable" This provision is required to accurately reflect plant design bases. The design basis events, which impose AFW safety function requirements, are loss of normal feedwater, main feedwater line breaks, main steam line breaks, loss of offsite power (LOOP), and small break loss of E1-3 | |||
coolant accidents. These design bases events assume AFW auto-start on either low-low SG level, safety injection or a LOOP signal. These engineered safety feature actuation system (ESFAS) signals are Class 1 E, which means that they meet all requirements for reliable power supplies, separation, redundancy, testability, seismic and environmental qualifications as specified in 10 CFR50.55a(h)(2), Protection systems. | |||
The anticipatory AFW auto-start circuits associated with the TDMFW pumps do not meet the code requirements specified in 10 CFR50.55a(h)(2). The oil pressure switches and relays that make up these circuits are not single failure proof, nor are they seismically qualified. These circuits do not interface with the ESFAS, which is an integral part of the Solid State Protection System. As such, these circuits are not part of the primary success path for postulated accident mitigation as defined by 10 CFR 50.36(c)(2)(ii), Criterion 3 and, therefore, are not credited in the accident analysis. The safety grade signals credited in the accident analysis for loss of normal feedwater are SG low-low level. | |||
TVA therefore concludes that since the primary success path for accident mitigation is provided by SG low-low level signals, loss of both anticipatory trip channels does not place the plant in an unanalyzed condition and, therefore, the plant should not be required to enter LCO 3.0.3. | |||
4.3 Proposed Change to LCO 3.3.2, Required Action J.1 The proposed change will revise LCO 3.3.2, Required Action J.1 to read: | |||
"Restore channel(s) to OPERABLE status." | |||
LCO 3.3.2, Condition J, applies to both anticipatory trip channels. The trip channels are combined using an "AND" logic circuit (see fig. 1). Failure of one or both channels results in loss of AFW auto-start function. Therefore, both trip channels must be declared OPERABLE within 48 hour of entering Condition J or be in Mode 3 in accordance with Required Action J.2. | |||
4.4 Proposed Change to Mode 2 Applicability for Function 6.e The proposed change will revise Mode 2 applicability for Function 6.e with the following note: | |||
'When one or more Turbine Driven Feedwater Pump(s) are supplying feedwater to steam generators." | |||
Since the AFW pumps are used as the primary means of removing heat from the reactor core in Mode 2, the anticipatory AFW auto-start function serves no useful purpose because the AFW system is already in service. If an AFW pump were to fail during startup or shutdown, the redundant AFW pump(s) would start automatically on low-low SG, if not already manually initiated by the operator in accordance with AOI-1 6, "Loss of Normal Feedwater." | |||
This proposed TS change is acceptable because, as stated before, between 2% and 4% RTP, a TDMFW pump is reset and placed into service. During the process of placing the first TDMFW pump in service, the anticipatory AFW auto-start channel for the non-operating TDMFW pump is placed in "bypass" (the electrical control circuit is de-energized) to prevent inadvertent AFW auto-start during rollup trip testing and overspeed trip testing. Once the operating TDMFW pump has established sufficient feed flow to maintain SG level, the anticipatory AFW auto-start channel for the non-operating TDMFW pump is placed in the "trip"condition, and the AFW pumps secured. Under these conditions the AFW auto start circuit will be in a half trip condition El -4 | |||
(one-out-of-two) in Mode 2 and during the transition from Mode 2 to Mode 1. If the operating TDMFW pump were to trip during this period an AFW auto-start signal would be generated causing all three AFW pumps to start. | |||
Modifying the requirement for auto-start of the AFW pumps to be required only when one or more TDMFW pump(s) are in service limits the potential for an overcooling transient due to inadvertent AFW actuation. Inadvertent AFW actuation during startup or shutdown would start all three AFW pumps including the turbine driven AFW pump. The steam demand to drive the turbine driven AFW pump at low power could lead to reactivity transients due to overcooling. | |||
For these reasons, TVA concludes that the anticipatory AFW auto-start channels need not be operational until a TDMFW pump is placed in service. | |||
4.5 Proposed Chanqe to Mode 1 Applicability for Function 6.e The proposed change will revise Mode 1 applicabilityfor Function 6.e with the following note: | |||
"Entry into Condition J may be suspended for up to 4 hours when placing the second turbine driven main feedwater (TDMFW) pump in service or removing one of two TDMFW pumps from service." | |||
This provision will allow placing the second TDMFW pump in service or removing one of the two TDMFW pumps from service during Mode 1 operations without the requirement to enter LCO 3.3.2, Condition J, for an inoperable channel. Entering into an LCO Action to place a system into service or remove a system from service is atypical without express allowance in the TS (e.g. the allowance associated with emergency core cooling system and low temperature overpressure protection system). This change is limited to a short period of time (4 hours) to allow operational flexibility to align the TDMFW pumps. This time is well within the allowed outage time of 48 hours as currently provided for one inoperable channel. In addition, plant safety is not compromised during this short period because the safety-grade AFW auto-start channels, i.e., SG low-low levels, are operable. | |||
4.6 Summary In summary, the proposed TS change will eliminate the requirement that LCO 3.3.2 Function 6.e be met in Mode 2 when the TDMFW pumps are not running and will allow one anticipatory AFW auto-start channel to be inoperable for a limited period in Mode 1 when placing the second TDMFW in or out of service. In the unlikely event that an AFW pump trip during plant startup or shutdown (i.e. Mode 2), the redundant AFW pumps would start automatically on low-low SG level, if not already manually initiated by the operator in accordance with AOl-1 6, "Loss of Normal Feedwater." | |||
==5.0 REGULATORY EVALUATION== | |||
5.1 Applicable Regulatory Requirements/Criteria Section 182a of the Atomic Energy Act requires applicants for nuclear power plant operating licenses to include technical specifications (TSs) as part of the license. The Commission's regulatory requirements related to the content of the TS are contained in Title 10, Code of Federal Regulations (10 CFR), Section 50.36, "Technical Specifications," of 10 CFR Part 50 "Domestic Licensing of Production and Utilization Facilities." The TS requirements in 10 CFR E1-5 | |||
50.36 include the following categories: (1) safety limits, limiting safety systems settings and control settings, (2) limiting conditions for operation, (3) surveillance requirements (SRs), (4) design features, and (5) administrative controls. The requirements for the initiation of AFW auto-start resulting from trip of all MFW pumps are included in the TS in accordance with 10 CFR 50.36(c)(2), "Limiting Conditions for Operation." | |||
As stated in 10 CFR 50.59(c)(1)(i), a licensee is required to submit a license amendment pursuant to 10 CFR 50.90 if a change to the TS is required. Furthermore, the requirements of 10 CFR 50.59 necessitate that the NRC approve the TS changes before the changes are implemented. TVA's submittal meets the requirements of 10 CFR 50.59(c)(1)(i) and 10 CFR 50.90. | |||
General Design Criterion (GDC) 13 "Instrumentation and Control," of Appendix A "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50 requires, among other things, that instrumentation be provided to monitor variables and systems and that controls be provided to maintain these variables and systems within prescribed operating ranges. The proposed operational change continues to provide system monitoring and proper actuation to satisfy the anticipatory trip function. No changes are proposed to the safety-related instrumentation (i.e., | |||
ESFAS). | |||
General Design Criteria (GDC) 20 through 29, "Protection and Reactivity Control Systems," of Appendix A, "General Design Criteria," to 10 CFR Part 50, provides the expectations for protection systems associated with reactor operation. The proposed change does not alter the ability for the reactor trip functions to actuate. The proposed operational allowance is consistent with the WBN Unit 1 design and analysis and ensures proper actuation to satisfy the anticipatory trip function. Therefore, the recommendations of these GDC continue to be met with the proposed change. | |||
5.2 Precedent Several operating facilities have been identified with similar operational TS allowances as proposed herein. These facilities include Sequoyah, Vogtle, Callaway, Indian Point 2, and Prairie Island. | |||
5.3 No Significant Hazards Consideration The proposed TS change will modify Mode 1 and 2 Applicability for Function 6.e of TS Table 3.3.2-1. In addition, the proposed change will also revise LCO 3.3.2, Condition J, to be consistent with plant design bases. TVA has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of amendment," as discussed below: | |||
: 1. Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated? | |||
Response: No. | |||
The design basis events which impose AFW safety function requirements are loss of normal main feedwater, main feed line or main steam line break, loss of offsite power (LOOP), and small break loss of coolant accident. These design bases event evaluations assume actuation of the AFW due to LOOP signal, low-low steam generator El -6 | |||
level or a safety injection signal. The anticipatory AFW auto-start signals from the turbine driven main feedwater (TDMFW) pumps are not credited in any design basis accidents and are, therefore, not part of the primary success path for postulated accident mitigation as defined by 10 CFR 50.36(c)(2)(ii), Criterion 3. Modifying Mode 1 and 2 Applicability for this function will not impact any previously evaluated design basis accidents. Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated. | |||
The | : 2. Does the proposed change create the possibility of a new or different kind of accident from any accident previously evaluated? | ||
Response: No. | |||
This TS change allows for an operational allowance during Mode 1 and 2 for placing TDMFW pumps in service or securing TDMFW pumps. This change involves an anticipatory AFW auto-start function that is not credited in the accident analysis. Since this change only affects the conditions at which this auto-start function needs to be operable and does not affect the function that actuates AFW due to loss of offsite power, low-low steam generator level or a safety injection signal, it will not be an initiator to a new or different kind of accident from any accident previously evaluated. | |||
: 3. Does the proposed change involve a significant reduction in margin of safety? | |||
Response: No. | |||
This TS change involves the automatic start of the AFW pumps due to trip of both TDMFW pumps, which is not an assumed start signal for design basis events. This change does not modify any values or limits involved in a safety related function or accident analysis. Therefore, the proposed change does not involve a significant reduction in a margin of safety. | |||
Based on the above, TVA concludes that the proposed amendment does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and accordingly, a finding of "no significant hazards consideration" is justified. | |||
5.4 Conclusions Based on the considerations discussed above, (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. | |||
== | ==6.0 ENVIRONMENTAL CONSIDERATION== | ||
A review has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve: (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. | |||
E1-7 | |||
Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment. | |||
===5. | ==7.0 REFERENCES== | ||
: 1. WBN UFSAR Section 10.4.7, "Condensate and Feedwater System" | |||
: 2. General Design Criteria (GDC) of 10 CFR 50 Appendix A, GDC 34 "Residual Heat Removal" | |||
: 3. Code of Federal Regulations 10 CFR 50.55a(h)(2), Protection systems | |||
: 4. NRC Standard Review Plan (SRP) 10.4.9, "Auxiliary Feedwateir System (PWR)" | |||
: 5. WBN UFSAR Section 15.2.8,"Loss of Normal Feedwater" E1-8 | |||
Simplified MFPT- A Anticipatory Trip Circuit (Channel B Similar) | |||
(1 | Channel A Reset - Bus Energized Channel A Trip - Bus Energized (Mode 1 and 2) (Mode 1 and 2) | ||
Bkr Closed Bkr Closed Hydraulic Press Hydraulic Press | |||
< 50 DSia 2>50 psig 00 | |||
> 0 LO) | |||
J AFW Ch. A L AFW Ch. A R Auto Start Auto Start T Reset ]- Trip Channel A Bypass - Bus De-energized Note: | |||
(Mode 2 Only) Anticipatory trip circuits are designed to energize to Bkr Open actuate. | |||
PS Hydraulic Press AFW Ch. A | |||
< 50 psig Auto Start 0 AFW Ch. B Auto Start LO C\j AFW Ch. A I- Initiate AFW System 7- Auto Start Bypass ~1~~~ Auto-Start Figure 1 E1-9 | |||
ENCLOSURE 2 PROPOSED TECHNICAL SPECIFICATION PAGE MARKUP | |||
: 1. AFFECTED TS PAGES TS 3.3-28 TS 3.3-38 | |||
: 2. See Attachment E2-1 | |||
ESFAS Instrumentation 3.3.2 Note: Deletions are strikethrough and additions are in bold italics ACTIONS (continued) | |||
CONDITION REQUIRED ACTION COMPLETION TIME I. One Steam Generator Water 1.1 -------- NOTE --------- | |||
CONDITION REQUIRED ACTION COMPLETION TIME I. One Steam Generator Water 1.1 -------- NOTE ---------Level--High High channel One channel may be inoperable, bypassed for up to 4 hours for surveillance testing.Place channel in trip. 6 hours OR 1.2.1 Be in MODE 3. 12 hours OR 1.2.2 Be in MODE 4. 18 hours J. One or more Turbine Driven J.1 Restore channel(s) to 48 hours Main Feedwater Pump trip OPERABLE status.channel(s) inoperable. | Level--High High channel One channel may be inoperable, bypassed for up to 4 hours for surveillance testing. | ||
OR J.2 Be in MODE 3. 54 hours K. One channel inoperable. | Place channel in trip. 6 hours OR 1.2.1 Be in MODE 3. 12 hours OR 1.2.2 Be in MODE 4. 18 hours J. One or more Turbine Driven J.1 Restore channel(s) to 48 hours Main Feedwater Pump trip OPERABLE status. | ||
K.1 -------- NOTE ---------One additional channel may be bypassed for up to 4 hours for surveillance testing.Place channel in 6 hours bypass. | channel(s) inoperable. | ||
___________________I (continued) | OR J.2 Be in MODE 3. 54 hours K. One channel inoperable. K.1 - ------- NOTE --------- | ||
Watts Bar-Unit 1 3.3-28 E2-2 | One additional channel may be bypassed for up to 4 hours for surveillance testing. | ||
Place channel in 6 hours bypass. | |||
OR | |||
___________________________ ___________________I (continued) | |||
Watts Bar-Unit 1 3.3-28 E2-2 | |||
ESFAS Instrumentation 3.3.2 Table 3.3.2-1 Engineered Safety Feature Actuation System Instrumentation APPLICABLE MODES NOMINAL OR OTHER REQUIRED SURVEILLANCE ALLOWABLE TRIP FUNCTION SPECIFIED CHANNELS CONDITIONS REQUIREMENT VALUE SETPOINT CONDITIONS S | |||
3.3.2-1 Engineered Safety Feature Actuation System Instrumentation APPLICABLE MODES NOMINAL OR OTHER REQUIRED SURVEILLANCE ALLOWABLE TRIP FUNCTION SPECIFIED CHANNELS CONDITIONS REQUIREMENT VALUE SETPOINT CONDITIONS S 6. Auxiliary Feedwater (continued) | : 6. Auxiliary Feedwater (continued) | ||
: c. Safety Refer to Function 1 (Safety Injection) for all initiation Injection functions and requirements. | : c. Safety Refer to Function 1 (Safety Injection) for all initiation Injection functions and requirements. | ||
: d. Loss of Offsite 1,2, 3 4 per bus F Refer to Function 4 of Table 3.3.5-1 for Power SRs and Allowable Values e.. Trip of all 1 per pump J SR 3.3.2.8 > 48 psig 50 psig Turbine Driven Main Feedwater SR 3.3.2.9 Pumps SR 3.3.2.10 f. Auxiliary 1,2,3 3 FSR 3.3.2.6 A) > 0.5 A) 1.2 Feedwater SR 3.3.2.9 psig psig Pumps SR 3.3.2.10 Train A and B B) > | : d. Loss of Offsite 1,2, 3 4 per bus F Refer to Function 4 of Table 3.3.5-1 for Power SRs and Allowable Values e.. Trip of all 1 per pump J SR 3.3.2.8 > 48 psig 50 psig Turbine Driven Main Feedwater SR 3.3.2.9 Pumps SR 3.3.2.10 | ||
Watts Bar-Unit 1 3.3-28 E2-3}} | : f. Auxiliary 1,2,3 3 FSR 3.3.2.6 A) > 0.5 A) 1.2 Feedwater SR 3.3.2.9 psig psig Pumps SR 3.3.2.10 Train A and B B) >_1.33 B) 2.0 Suction psig psig Transfer on Suction Pressure - Low | ||
: 7. Automatic Switchover to Containment Sump | |||
: a. Automatic 1,2, 3, 4 2 trains C SR 3.3.2.2 NA NA Actuation SR 3.3.2.3 Logic and Actuation SR 3.3.2.5 Relays (continued) | |||
(i) Entry into Condition J may be suspended for up to 4 hours when placing the second turbine driven main feedwater (TDMFW) pump in service or removing one of two TDMFW pumps from service. | |||
When one or more Turbine Driven FeedwaterPump(s) are supplying feedwater to steam generators. | |||
Watts Bar-Unit 1 3.3-28 E2-3}} |
Latest revision as of 12:42, 14 November 2019
ML082670543 | |
Person / Time | |
---|---|
Site: | Watts Bar |
Issue date: | 09/18/2008 |
From: | Brandon M Tennessee Valley Authority |
To: | Document Control Desk, Office of Nuclear Reactor Regulation |
References | |
WBN-TS-08-07 | |
Download: ML082670543 (15) | |
Text
Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 September 18, 2008 WBN-TS-08-07 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Gentlemen:
In the Matter of ) Docket No.50-390 Tennessee Valley Authority )
WATTS BAR NUCLEAR PLANT (WBN) UNIT 1 - TECHNICAL SPECIFICATION (TS)
CHANGE NO. 08-07, AUXILIARY FEEDWATER AUTO-START UPON TRIP OF THE TURBINE DRIVEN MAIN FEEDWATER PUMPS The U.S. Nuclear Regulatory Commission (NRC) recently issued Inspection Report 2008-003, dated August 7, 2008, to Watts Bar Nuclear (WBN) Plant. In this report, NRC informed the Tennessee Valley Authority (TVA) that plant operation is not conforming to TS 3.3,2 Function 6.e when a non-operating turbine driven main feedwater (TDMFW) pump is reset and entering Mode 2. TVA had previously considered the associated auxiliary feedwater (AFW) auto-start channel operable; however, NRC informed TVA that a non-operating TDMFW pump in the reset condition impacts operability of the AFW auto-start channel due to the invalid indication of the TDMFW pump status.
Therefore, pursuant to 10 CFR 50.90, TVA is submitting a request for a TS change (TS-08-07) to license NPF-90 for WBN Unit 1. The proposed TS change will modify Mode 1 and 2 Applicability for Function 6.e of TS Table 3.3.2-1, "Engineered Safety Feature Actuation System Instrumentation." This safety function is associated with AFW automatic start on Trip of all Main Feedwater Pumps. In addition, the proposed change will also revise limiting condition for operation (LCO) 3.3.2, Condition J, to be consistent with WBN Unit 1 design bases.
Function 6.e of TS Table 3.3.2-1 is an anticipatory function that provides early actuation of the AFW system but is not required by the accident analysis for WBN. Current TS requires that this function be operable in Mode 2 prior to the availability of sufficient
'feedwater demand to run a TDMFW pump.
U.S. Nuclear Regulatory Commission Page 2 September 1 8, 2008 to this letter provides the description and evaluation of the proposed TS change. TVA has determined that the proposed change does not involve a significant hazards consideration, and the TS change qualifies for a categorical exclusion from environmental review pursuant to the provisions of 10 CFR 51.22(c)(9). Additionally, in accordance with 10 CFR 50.91 (b)(1), TVA is sending a copy of this letter and attachments to the Tennessee State Department of Public Health. contains copies of the appropriate TS pages marked-up to show the proposed change.
TVA requests approval of this amendment, as soon as practical, but not later than September 1, 2009 to support restart from the Cycle 9 refueling outage. TVA requests a 45 day implementation period for the approved TS change.
There are no commitments associated with this submittal.
If you have any questions about this change, please contact R. L. Clark at (423) 365-1818 or me at (423) 365-1824.
I declare under penalty of perjury that the foregoing is true and correct. Executed on this 18th day of September, 2008.
Sincerely, M. K. Brandon
Enclosures:
- 1. TVA Evaluation of Proposed Technical Specifications Change
- 2. Proposed Technical Specifications Change (Mark-Up) cc: See page 3
U.S. Nuclear Regulatory Commission Page 3 September 18, 2008 Enclosures cc (Enclosures 1-2):
NRC Resident Inspector Watts Bar Nuclear Plant 1260 Nuclear Plant Road Spring City, Tennessee 37381 ATTN: Patrick D. Milano, Project Manager U.S. Nuclear Regulatory Commission Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation MS 08H4 Washington, DC 20555-0001 U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 Mr. Lawrence E. Nanny, Director Division of Radiological Health 3 d Floor L & C Annex 401 Church Street Nashville, Tennessee 37243
ENCLOSURE1 TENNESSEE VALLEY AUTHORITY (TVA)
UNIT 1 TVA EVALUATION OF PROPOSED CHANGE 1.0
SUMMARY
DESCRIPTION This evaluation supports a request to amend Operating License NPF-90 for WBN Unit 1. The proposed TS change will modify Mode 1 and 2 Applicability for Function 6.e of Table 3.3.2-1, "Engineered Safety Feature Actuation System Instrumentation." This safety function is associated with the automatic start of the auxiliary feedwater (AFW) system upon Trip of all Main Feedwater (MFW) Pumps. In addition, the proposed change will also revise limiting condition for operation (LCO) 3.3.2, Condition J, to be consistent with WBN Unit 1 design bases.
On August 7, 2008, the NRC issued, Watts Bar Nuclear Plant - Inspection Report 2008-003. In this report, the NRC informed TVA that plant operation did not conform to TS 3.3.2 Function 6.e when a non-operating TDMFW pump is reset and entering Mode 2. TVA had previously considered the associated AFW auto-start channel operable; however, NRC informed TVA that a non-operating TDMFW pump in the reset condition impacts operability of the AFW auto-start channel due to the false (i.e., invalid) indication of the TDMFW pump status. This change will permanently address this startup and shutdown issue.
For WBN Unit 1 to comply with the current TS for entry into Mode 2, each TDMFW pump would need to be in a tripped condition. This configuration would result in an auto-start of the motor driven and turbine driven AFW pumps. The presence of such an automatic AFW system start signal at this point in the plant startup sequence (Mode 3 to Mode 2) is an unnecessary burden on the operators because the steam generator (SG) demand for feedwater is too low to require operation of all three AFW pumps.
2.0 DETAILED DESCRIPTION The AFW auto-start function on Trip of all MFW Pumps is an anticipatory function in that it provides early actuation of the AFW system to mitigate the consequences of a loss of normal feedwater which is a Condition II Fault. The current TS requires that this function be operable in Mode 2 prior to the availability of sufficient feedwater demand to run a TDMFW pump.
The proposed TS change will:
(1) Modify Function 6.e of TS Table 3.3.2-1 to read:
'Trip of all Turbine Driven Main Feedwater Pumps."
(2) Modify LCO 3.3.2, Condition J to read:
"One or more Turbine Driven Main Feedwater Pump trip channel(s) inoperable."
(3) Modify LCO 3.3.2, Required Action J. 1 to read:
El -1
"Restore channel(s) to OPERABLE status."
(4) Add the following footnote to Mode 1 Applicability for Function 6.e of TS Table 3.3.2-1:
"Entry into Condition J may be suspended for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> when placing the second turbine driven main feedwater (TDMFW) pump in service or removing one of two TDMFW pumps from service."
(5) Add the following footnote to Mode 2 Applicability for Function 6.e of TS Table 3.3.2-1:
'When one or more Turbine Driven Feedwater Pump(s) are supplying feedwater to steam generators."
The proposed TS changes listed above are necessary to resolve the compliance issue NRC brought to TVA's attention.
3.0 BACKGROUND
The condensate and feedwater systems are designed to provide feedwater to the SG secondary side during normal plant operating conditions and to guarantee that feedwater will not be delivered to the SGs when feedwater isolation is required. The systems are designed to take suction from the main condenser hotwell and deliver feed flow to the SGs at elevated temperature and pressure. These systems consist of many components including 3 hotwell pumps, 3 condensate booster pumps, 2 TDMFW pumps and one standby motor driven (SBMFW) pump along with high and low pressure feedwater heaters, demineralizers and other major equipment needed to process feed flow. Additional information can be found in Updated Final Safety Analysis Report (UFSAR) Section 10.4.7, "Condensate and Feedwater System."
The SBMFW pump was originally designed to provide feed flow during startup and shutdown conditions below 15% rated thermal power (RTP) and to accommodate loss of one TDMFW pump above 67% RTP. Due to the non-compliance issues addressed in NRC Inspection Reports 2006-004 and 2008-003, the AFW motor driven pumps and the TDMFW pumps will be used for normal plant startup and shutdown in compliance with this proposed change.
Each TDMFW pump is equipped with one oil pressure switch located in the turbine's hydraulic control circuit which makes up one channel of the AFW auto-start circuit. A low pressure signal from this pressure switch indicates a trip of that pump, and a trip of both TDMFW pumps will automatically start the motor driven and turbine driven AFW pumps. Currently, LCO 3.3.2, Function 6.e, requires that automatic start of the AFW pumps be operable during Mode 2 even when no TDMFW pumps are in operation.
The AFW auto-start channel for each TDMFW pump is "reset" when the TDMFW pump's electrical control circuit is energized and the pressure switch located in the turbine's hydraulic control circuit senses that the circuit is pressurized (> 50 psig). The TDMFW pump is considered to be in service when the pump is providing feed flow to the SGs. The AFW auto-start channel is in the "trip" condition when the TDMFW pump's electrical control circuit is energized and the hydraulic control circuit is depressurized (< 50 psig). The TDMFW pump is considered to be out of service when the pump is not providing feed flow to the SGs. Because the anticipatory AFW system actuation circuits are designed "energize-to-actuate", the AFW auto-start channel is in the "bypass" condition whenever the TDMFW pump's electrical control circuit is de-energized regardless if the hydraulic control circuit is pressurized or not (see Fig. 1).
El -2
When entering Mode 2, the AFW system is placed into service to control and maintain SG level.
Between 2% and 4% RTP, a TDMFW pump is "reset", as described above, and placed into service. During the process of placing one TDMFW pump in service, the electrical control circuit for the non-operating TDMFW pump is de-energized which places its associated AFW auto-start channel in the "bypass" condition. This action is necessary to prevent inadvertent AFW system actuation during rollup trip testing and overspeed trip testing of the operating TDMFW pump.
Once the operating TDMFW pump has established sufficient feed flow to maintain SG level, the electrical control circuit for the non-operating TDMFW pump is re-energized, and its associated AFW auto-start channel is placed in the '"trip" condition. During this time the main feedwater system is in service and the AFW pumps are taken out of service. Under these conditions the AFW auto start circuit will be in a half trip condition (one-out-of-two) in Mode 2 and during the transition from Mode 2 to Mode 1. If the operating TDMFW pump were to trip during this period, an AFW auto-start signal would be generated causing all three AFW pumps to start.
After entering Mode 1 the second TDMFW pump is reset and placed into service (approximately 50% RTP). This process requires less than 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to complete. During this process, the second TDMFW pump is placed on turning gear, the auxiliary support systems such as injection water, gland steam sealing, steam drains, raw cooling water, and lube oil are aligned and placed into operation. Afterwards, the main feed pump (MFP) turbine vacuum is established, the turbine rolled, and the MFP temperature increased to normal operating levels. With both TDMFW pumps in service and both AFW auto-start channels in "reset", the AFW auto-start function is fully operational.
During plant shutdown, the sequence of events is reversed. At a prescribed power level above 50% RTP, one TDMFW pump is removed from service and is placed in the tripped condition.
4.0 TECHNICAL ANALYSIS
The proposed TS change to revise LCO 3.3.2, Condition J, Required Action J.1, and Function 6.e of TS Table 3.3.2-1 are given below.
4.1 Proposed Change to Function 6.e of Table 3.3.2-1 The proposed change will revise Function 6.e of Table 3.3.2-1 to read:
"Trip of all Turbine Driven Main Feedwater Pumps" This change is necessary to clarify that this trip function is only applicable to the TDMFW pumps and not the SBMFW pump. This change is administrative in nature. It does not alter any TS requirements or operational restrictions and therefore does not affect plant safety.
4.2 Proposed Change to LCO 3.3.2, Condition J The proposed change will revise LCO 3.3.2, Condition J to read:
"One or more Turbine Driven Main Feedwater Pump trip channel(s) inoperable" This provision is required to accurately reflect plant design bases. The design basis events, which impose AFW safety function requirements, are loss of normal feedwater, main feedwater line breaks, main steam line breaks, loss of offsite power (LOOP), and small break loss of E1-3
coolant accidents. These design bases events assume AFW auto-start on either low-low SG level, safety injection or a LOOP signal. These engineered safety feature actuation system (ESFAS) signals are Class 1 E, which means that they meet all requirements for reliable power supplies, separation, redundancy, testability, seismic and environmental qualifications as specified in 10 CFR50.55a(h)(2), Protection systems.
The anticipatory AFW auto-start circuits associated with the TDMFW pumps do not meet the code requirements specified in 10 CFR50.55a(h)(2). The oil pressure switches and relays that make up these circuits are not single failure proof, nor are they seismically qualified. These circuits do not interface with the ESFAS, which is an integral part of the Solid State Protection System. As such, these circuits are not part of the primary success path for postulated accident mitigation as defined by 10 CFR 50.36(c)(2)(ii), Criterion 3 and, therefore, are not credited in the accident analysis. The safety grade signals credited in the accident analysis for loss of normal feedwater are SG low-low level.
TVA therefore concludes that since the primary success path for accident mitigation is provided by SG low-low level signals, loss of both anticipatory trip channels does not place the plant in an unanalyzed condition and, therefore, the plant should not be required to enter LCO 3.0.3.
4.3 Proposed Change to LCO 3.3.2, Required Action J.1 The proposed change will revise LCO 3.3.2, Required Action J.1 to read:
"Restore channel(s) to OPERABLE status."
LCO 3.3.2, Condition J, applies to both anticipatory trip channels. The trip channels are combined using an "AND" logic circuit (see fig. 1). Failure of one or both channels results in loss of AFW auto-start function. Therefore, both trip channels must be declared OPERABLE within 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of entering Condition J or be in Mode 3 in accordance with Required Action J.2.
4.4 Proposed Change to Mode 2 Applicability for Function 6.e The proposed change will revise Mode 2 applicability for Function 6.e with the following note:
'When one or more Turbine Driven Feedwater Pump(s) are supplying feedwater to steam generators."
Since the AFW pumps are used as the primary means of removing heat from the reactor core in Mode 2, the anticipatory AFW auto-start function serves no useful purpose because the AFW system is already in service. If an AFW pump were to fail during startup or shutdown, the redundant AFW pump(s) would start automatically on low-low SG, if not already manually initiated by the operator in accordance with AOI-1 6, "Loss of Normal Feedwater."
This proposed TS change is acceptable because, as stated before, between 2% and 4% RTP, a TDMFW pump is reset and placed into service. During the process of placing the first TDMFW pump in service, the anticipatory AFW auto-start channel for the non-operating TDMFW pump is placed in "bypass" (the electrical control circuit is de-energized) to prevent inadvertent AFW auto-start during rollup trip testing and overspeed trip testing. Once the operating TDMFW pump has established sufficient feed flow to maintain SG level, the anticipatory AFW auto-start channel for the non-operating TDMFW pump is placed in the "trip"condition, and the AFW pumps secured. Under these conditions the AFW auto start circuit will be in a half trip condition El -4
(one-out-of-two) in Mode 2 and during the transition from Mode 2 to Mode 1. If the operating TDMFW pump were to trip during this period an AFW auto-start signal would be generated causing all three AFW pumps to start.
Modifying the requirement for auto-start of the AFW pumps to be required only when one or more TDMFW pump(s) are in service limits the potential for an overcooling transient due to inadvertent AFW actuation. Inadvertent AFW actuation during startup or shutdown would start all three AFW pumps including the turbine driven AFW pump. The steam demand to drive the turbine driven AFW pump at low power could lead to reactivity transients due to overcooling.
For these reasons, TVA concludes that the anticipatory AFW auto-start channels need not be operational until a TDMFW pump is placed in service.
4.5 Proposed Chanqe to Mode 1 Applicability for Function 6.e The proposed change will revise Mode 1 applicabilityfor Function 6.e with the following note:
"Entry into Condition J may be suspended for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> when placing the second turbine driven main feedwater (TDMFW) pump in service or removing one of two TDMFW pumps from service."
This provision will allow placing the second TDMFW pump in service or removing one of the two TDMFW pumps from service during Mode 1 operations without the requirement to enter LCO 3.3.2, Condition J, for an inoperable channel. Entering into an LCO Action to place a system into service or remove a system from service is atypical without express allowance in the TS (e.g. the allowance associated with emergency core cooling system and low temperature overpressure protection system). This change is limited to a short period of time (4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />) to allow operational flexibility to align the TDMFW pumps. This time is well within the allowed outage time of 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> as currently provided for one inoperable channel. In addition, plant safety is not compromised during this short period because the safety-grade AFW auto-start channels, i.e., SG low-low levels, are operable.
4.6 Summary In summary, the proposed TS change will eliminate the requirement that LCO 3.3.2 Function 6.e be met in Mode 2 when the TDMFW pumps are not running and will allow one anticipatory AFW auto-start channel to be inoperable for a limited period in Mode 1 when placing the second TDMFW in or out of service. In the unlikely event that an AFW pump trip during plant startup or shutdown (i.e. Mode 2), the redundant AFW pumps would start automatically on low-low SG level, if not already manually initiated by the operator in accordance with AOl-1 6, "Loss of Normal Feedwater."
5.0 REGULATORY EVALUATION
5.1 Applicable Regulatory Requirements/Criteria Section 182a of the Atomic Energy Act requires applicants for nuclear power plant operating licenses to include technical specifications (TSs) as part of the license. The Commission's regulatory requirements related to the content of the TS are contained in Title 10, Code of Federal Regulations (10 CFR), Section 50.36, "Technical Specifications," of 10 CFR Part 50 "Domestic Licensing of Production and Utilization Facilities." The TS requirements in 10 CFR E1-5
50.36 include the following categories: (1) safety limits, limiting safety systems settings and control settings, (2) limiting conditions for operation, (3) surveillance requirements (SRs), (4) design features, and (5) administrative controls. The requirements for the initiation of AFW auto-start resulting from trip of all MFW pumps are included in the TS in accordance with 10 CFR 50.36(c)(2), "Limiting Conditions for Operation."
As stated in 10 CFR 50.59(c)(1)(i), a licensee is required to submit a license amendment pursuant to 10 CFR 50.90 if a change to the TS is required. Furthermore, the requirements of 10 CFR 50.59 necessitate that the NRC approve the TS changes before the changes are implemented. TVA's submittal meets the requirements of 10 CFR 50.59(c)(1)(i) and 10 CFR 50.90.
General Design Criterion (GDC) 13 "Instrumentation and Control," of Appendix A "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50 requires, among other things, that instrumentation be provided to monitor variables and systems and that controls be provided to maintain these variables and systems within prescribed operating ranges. The proposed operational change continues to provide system monitoring and proper actuation to satisfy the anticipatory trip function. No changes are proposed to the safety-related instrumentation (i.e.,
ESFAS).
General Design Criteria (GDC) 20 through 29, "Protection and Reactivity Control Systems," of Appendix A, "General Design Criteria," to 10 CFR Part 50, provides the expectations for protection systems associated with reactor operation. The proposed change does not alter the ability for the reactor trip functions to actuate. The proposed operational allowance is consistent with the WBN Unit 1 design and analysis and ensures proper actuation to satisfy the anticipatory trip function. Therefore, the recommendations of these GDC continue to be met with the proposed change.
5.2 Precedent Several operating facilities have been identified with similar operational TS allowances as proposed herein. These facilities include Sequoyah, Vogtle, Callaway, Indian Point 2, and Prairie Island.
5.3 No Significant Hazards Consideration The proposed TS change will modify Mode 1 and 2 Applicability for Function 6.e of TS Table 3.3.2-1. In addition, the proposed change will also revise LCO 3.3.2, Condition J, to be consistent with plant design bases. TVA has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of amendment," as discussed below:
- 1. Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?
Response: No.
The design basis events which impose AFW safety function requirements are loss of normal main feedwater, main feed line or main steam line break, loss of offsite power (LOOP), and small break loss of coolant accident. These design bases event evaluations assume actuation of the AFW due to LOOP signal, low-low steam generator El -6
level or a safety injection signal. The anticipatory AFW auto-start signals from the turbine driven main feedwater (TDMFW) pumps are not credited in any design basis accidents and are, therefore, not part of the primary success path for postulated accident mitigation as defined by 10 CFR 50.36(c)(2)(ii), Criterion 3. Modifying Mode 1 and 2 Applicability for this function will not impact any previously evaluated design basis accidents. Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.
- 2. Does the proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?
Response: No.
This TS change allows for an operational allowance during Mode 1 and 2 for placing TDMFW pumps in service or securing TDMFW pumps. This change involves an anticipatory AFW auto-start function that is not credited in the accident analysis. Since this change only affects the conditions at which this auto-start function needs to be operable and does not affect the function that actuates AFW due to loss of offsite power, low-low steam generator level or a safety injection signal, it will not be an initiator to a new or different kind of accident from any accident previously evaluated.
- 3. Does the proposed change involve a significant reduction in margin of safety?
Response: No.
This TS change involves the automatic start of the AFW pumps due to trip of both TDMFW pumps, which is not an assumed start signal for design basis events. This change does not modify any values or limits involved in a safety related function or accident analysis. Therefore, the proposed change does not involve a significant reduction in a margin of safety.
Based on the above, TVA concludes that the proposed amendment does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and accordingly, a finding of "no significant hazards consideration" is justified.
5.4 Conclusions Based on the considerations discussed above, (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.
6.0 ENVIRONMENTAL CONSIDERATION
A review has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve: (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure.
E1-7
Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.
7.0 REFERENCES
- 2. General Design Criteria (GDC) of 10 CFR 50 Appendix A, GDC 34 "Residual Heat Removal"
- 3. Code of Federal Regulations 10 CFR 50.55a(h)(2), Protection systems
Simplified MFPT- A Anticipatory Trip Circuit (Channel B Similar)
Channel A Reset - Bus Energized Channel A Trip - Bus Energized (Mode 1 and 2) (Mode 1 and 2)
Bkr Closed Bkr Closed Hydraulic Press Hydraulic Press
< 50 DSia 2>50 psig 00
> 0 LO)
J AFW Ch. A L AFW Ch. A R Auto Start Auto Start T Reset ]- Trip Channel A Bypass - Bus De-energized Note:
(Mode 2 Only) Anticipatory trip circuits are designed to energize to Bkr Open actuate.
PS Hydraulic Press AFW Ch. A
< 50 psig Auto Start 0 AFW Ch. B Auto Start LO C\j AFW Ch. A I- Initiate AFW System 7- Auto Start Bypass ~1~~~ Auto-Start Figure 1 E1-9
ENCLOSURE 2 PROPOSED TECHNICAL SPECIFICATION PAGE MARKUP
- 1. AFFECTED TS PAGES TS 3.3-28 TS 3.3-38
- 2. See Attachment E2-1
ESFAS Instrumentation 3.3.2 Note: Deletions are strikethrough and additions are in bold italics ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME I. One Steam Generator Water 1.1 -------- NOTE ---------
Level--High High channel One channel may be inoperable, bypassed for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for surveillance testing.
Place channel in trip. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> OR 1.2.1 Be in MODE 3. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> OR 1.2.2 Be in MODE 4. 18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br /> J. One or more Turbine Driven J.1 Restore channel(s) to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> Main Feedwater Pump trip OPERABLE status.
channel(s) inoperable.
OR J.2 Be in MODE 3. 54 hours6.25e-4 days <br />0.015 hours <br />8.928571e-5 weeks <br />2.0547e-5 months <br /> K. One channel inoperable. K.1 - ------- NOTE ---------
One additional channel may be bypassed for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for surveillance testing.
Place channel in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> bypass.
___________________________ ___________________I (continued)
Watts Bar-Unit 1 3.3-28 E2-2
ESFAS Instrumentation 3.3.2 Table 3.3.2-1 Engineered Safety Feature Actuation System Instrumentation APPLICABLE MODES NOMINAL OR OTHER REQUIRED SURVEILLANCE ALLOWABLE TRIP FUNCTION SPECIFIED CHANNELS CONDITIONS REQUIREMENT VALUE SETPOINT CONDITIONS S
- 6. Auxiliary Feedwater (continued)
- c. Safety Refer to Function 1 (Safety Injection) for all initiation Injection functions and requirements.
- d. Loss of Offsite 1,2, 3 4 per bus F Refer to Function 4 of Table 3.3.5-1 for Power SRs and Allowable Values e.. Trip of all 1 per pump J SR 3.3.2.8 > 48 psig 50 psig Turbine Driven Main Feedwater SR 3.3.2.9 Pumps SR 3.3.2.10
- f. Auxiliary 1,2,3 3 FSR 3.3.2.6 A) > 0.5 A) 1.2 Feedwater SR 3.3.2.9 psig psig Pumps SR 3.3.2.10 Train A and B B) >_1.33 B) 2.0 Suction psig psig Transfer on Suction Pressure - Low
- 7. Automatic Switchover to Containment Sump
- a. Automatic 1,2, 3, 4 2 trains C SR 3.3.2.2 NA NA Actuation SR 3.3.2.3 Logic and Actuation SR 3.3.2.5 Relays (continued)
(i) Entry into Condition J may be suspended for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> when placing the second turbine driven main feedwater (TDMFW) pump in service or removing one of two TDMFW pumps from service.
When one or more Turbine Driven FeedwaterPump(s) are supplying feedwater to steam generators.
Watts Bar-Unit 1 3.3-28 E2-3