ML042740448

Technical Specification (TS) Change No.04-013 - Auxiliary Feedwater (AFW) Start Upon Trip of Turbine Driven Main Feedwater (Tdmfw) Pumps

ML042740448
Person / Time
Site:	Watts Bar
Issue date:	09/23/2004
From:	Pace P Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
WBN-TS-04-013
Download: ML042740448 (15)

Text

{{#Wiki_filter:Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 SEP 2 3 2004 WBN-TS-04-013 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. 04-013 - AUXILIARY FEEDWATER (AFW) START UPON TRIP OF TURBINE DRIVEN MAIN FEEDWATER (TDMFW) PUMPS Pursuant to 10 CFR 50.90, TVA is submitting a request for a TS change (WBN-TS-04-013) to license NPF-90 for WBN Unit 1. The proposed TS change revises Limiting Condition for Operation (LCO) 3.3.2 (6)(e) to allow the AFW Start upon Trip of TDMFW Pump function to be required only when the one or more of TDMFW Pumps are operating. This function is an anticipatory circuit which provides early actuation of the AFW system but it is not a safety-related function. Current TS requires this function to be operable prior to adequate steam being available to run the TDMFW pumps. By making the proposed change, this trip function can be made operable later in the unit startup timeline resulting in additional time to spread a number of activities, which prepare the MFW pumps for operation, over a longer duration minimizing the potential for human performance errors. P-ed roncydpaw

U.S. Nuclear Regulatory Commission Page 2 SEP 2 3 2004 to this letter provides the description and evaluation of the proposed 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. Enclosure 3 contains the updated TS pages with the proposed change incorporated. provides, for information only, the marked-up TS Bases page B 3.3-93 associated with this proposed change. TVA requests approval of this amendment as soon as practical in support of the Spring 2005 Cycle 6 Refueling Outage. Further, TVA requests that implementation of the revised TS be prior to entering Mode 2 following the refueling outage. TVA is prepared to meet with the Staff if necessary, to facilitate the NRC's review. No commitments are made by this letter. If you have any questions about this change, please contact me at (423) 365-1824. I declare under penalty of perjury that the foregoing is true and correct. Executed on 23th day of September 2004. Sincerely, P. L. Pace Manager, Site Licensing and Industry Affairs

Enclosures:

1. TVA's Evaluation of the Proposed Change

2. Proposed Technical Specification Change (Marked-up)

3. Proposed Technical Specification Change (Retyped)

4. Proposed Technical Specification Bases Change (Marked-up) cc: See page 3

U.S. Nuclear Regulatory Commission Page 3 SEP 2 3 2004 cc (Enclosures): NRC Resident Inspector Watts Bar Nuclear Plant 1260 Nuclear Plant Road Spring City, Tennessee 37381 Mr. R. J. Pascarelli, Project Manager U.S. Nuclear Regulatory Commission MS 07A15 One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2738 U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 Mr. Lawrence E. Nanney, Director Division of Radiological Health Third Floor L&C Annex 401 church Street Nashville, Tennessee 37243-1532

ENCLOSURE 1 TENNESSEE VALLEY AUTHORITY (TVA) WATTS BAR NUCLEAR PLANT (WBN) UNIT 1 TVA EVALUATION OF PROPOSED CHANGE

1.0 DESCRIPTION

This proposed Technical Specification (TS) change will revise Limiting Condition for Operation (LCO) 3.3.2 (6)(e) to allow Auxiliary Feedwater (AFW) start upon trip of Turbine Driven Main Feedwater (TDMFW) Pump function to be required only when one or more of TDMFW pumps are operating. This proposed change will also require a clarification to the TS Bases section 3.3.2 to describe this arrangement. The AFW start function is an anticipatory circuit which provides early actuation of the AFW system but it is not a safety-related function. Current TS requires this function to be operable upon entry into Mode 1 or 2 which is prior to adequate steam being available to run the TDMFW pumps. This proposed change will allow the trip function to be made operable at a later time which will eliminate additional work for plant maintenance upon plant startup and decrease the duration of plant outages.

2.0 PROPOSED CHANGE

This proposed TS change will modify the mode applicability for function 6(e) of TS Table 3.3.2-1. Specifically, a footnote will be added to the applicable modes for this function, to clarify that this function is only required in Modes 1 and 2 when one or more TDMFW Pumps are operating. Enclosure 2 provides the TS page mark-up of these changes.

3.0 BACKGROUND

The safety-related AFW system supplies feedwater to the steam generators in the event of a loss of MFW to remove reactor decay heat and avoid reactor coolant system over pressurization. Upon startup at WBN, a motor driven Standby Main Feedpump is primarily used for plant startup when sufficient steam is not yet available to supply the TDMFW pumps. The standby pump is also available to supplement the two TDMFW pumps designed for normal operation. El-1

Each TDMFW pump is equipped with one pressure switch on the control oil line for the speed control system. A low pressure signal from this pressure switch indicates a trip of that pump and a trip of both TDMFW pumps starts the motor driven and turbine driven AFW pumps. LCO function 3.3.2,(6)(e) requires the automatic start of the AFW system on trip of both TDMFW pumps to be operable during modes 1 and 2. Typically, during plant refueling outages, one of the main feedwater pump turbines is disassembled to perform periodic preventative maintenance. This work requires the removal of sensitive instrumentation to prevent damage to these instruments while the pump is undergoing full disassembly. Near the end of outage when the pump is being reassembled, a number of activities need to be completed within a short duration including the replacement of the sensitive instrumentation. In conjunction with oil pump flushing, these instruments require calibration prior to testing of the entire MFW pump turbine. During plant startup and up to approximately 18 percent load, the motor driven Standby Main Feedwater Pump (SBMFP) is normally used instead of the TDMFW pumps as sufficient steam is not yet available. Once steam is established, the main feedwater pumps are placed into operation. It is also important to note that in the unlikely event that the SBMFP trips, in addition to autostart of AFW upon Steam Generator Lo-Lo Level, AFW can be manually started to supply the required necessary feedwater and continue with plant startup until sufficient steam is generated for the TDMFW pump's supply. As stated above currently the AFW Start upon Trip of Main Feedwater Pump function for the both pumps must be operable during this time to satisfy LCO 3.3.2 (6)(e) even though the MFW pumps are not running. This proposed TS change will revise this LCO to allow this function to be required only when one or more of the TDMFW pumps are operating. Thus, this will provide the time from initial entry into Mode 2 until approximately 18 percent power when the TDMFW pumps are placed into operation to accomplish the previously described work activities. In summary, by making the proposed change, this trip function can be made operable later in the unit startup timeline resulting in additional time to spread a number of activities, which prepare the TDMFW pumps for operation over a longer duration, minimizing the potential for human performance errors.

4.0 TECHNICAL ANALYSIS

LCO 3.3.2,(6)(e) is an anticipatory function which provides early actuation of the AFW system but it is not a safety-related function. Steam generator low-low level or a safety injection (SI) signal are the safety related signals credited for actuating E1-2

the AFW system during an accident. The TDMFW pump oil pressure switches, which indicate a trip of their respective pump, are non-quality related and there is no redundancy for this function (i.e., only one switch per pump). This proposed TS change will only change this function during mode 2 and the part of mode 1 where both TDMFW pumps are not operating (less than 18 percent load). During startup, the plant is being monitored very closely and the need for AFW is less than at full power. If the SBMFP should trip during this time, the AFW system would be started automatically by a low-low steam generator level signal or by operator manual initiation. The loss of one TDMFW pump during normal operation (100 percent power) will cause automatic start of the SBMFP, isolation of the condensate flow through the tripped main feed pump turbine's condenser, and main turbine runback to below 85 percent unit load. This results in feedwater flow being restored to the steam generators within 20 seconds of the loss of one TDMFW Pump which prevents a reactor trip due to low steam generator level. During this scenario, the auto start circuit for the AFW system is half made up and should the other TDMFW Pump trip, AFW start will actuate. The design basis events, which impose AFW safety function requirements, are loss of normal MFW, main feedline or main steamline break, loss of offsite power, loss of coolant accident, and small break loss of coolant accident. These accident evaluations assume actuation of AFW occurring due to low-low steam generator level or a safety injection signal. Start of AFW due to trip of the TDMFW pumps has not been credited in either the transient or accident analyses. In summary, start of AFW due to trip of both TDMFW pumps is required by TS LCO 3.3.2 (6)(e) but it is not a safety related feature and is not credited in either transient or accident analyses. This proposed TS change will only require AFW automatic start on trip of both TDMFW pumps during modes 1 and 2 when the TDMFW pumps are operating. In the unlikely event that SBMFP trips during plant startup, the AFW system will still have automatic start due to a low-low steam generator level signal or the operator can manually initiate AFW and continue startup until such time as steam would be available to start one of the TDMFW pumps. 5.0 REGULATORY SAFETY ANALYSIS 5.1 No Significant Hazards Consideration The proposed Technical Specification (TS) change will modify the mode applicability for function (6)(e) of TS Table 3.3.2-1. Specifically, a footnote will be added to the applicable modes for this function, to clarify that the Auxiliary Feedwater (AFW) start function upon trip of the Turbine Driven Main Feedwater (TDMFW) pumps is only required in Modes 1 and 2 when E1-3

one or more TDMFW Pumps are operating. 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 feedline or main steamline break, loss of offsite power, loss of coolant accident, and small break loss of coolant accident. These accident evaluations assume actuation of AFW occurring due to low-low steam generator level or a safety injection signal. These signals are required safety related features unlike start-up of the AFW pumps due to the trip of both TDMFW pumps which is an anticipatory function and not required for either transient or accident analyses. Requiring this function only when the TDMFW pumps are running will not impact any previously evaluated design basis events. 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 involves the automatic start of the AFW pumps when the TDMFW Pumps trip. This change involves a function that is not a safety related feature and, therefore, is not credited in either transient or accident analyses. Since this change only affects the point at which this trip function needs to be operable and does not affect the function that actuates AFW due to 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. E1-4

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 when the TDMFW pumps trip which is not a safety related plant function. This change does not change any values or limits involved in a safety related function. 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. 5.2 Applicable Regulatory Requirements/Criteria Regulatory requirements and criteria applicable to the design bases for the AFW system are provided in the WBN UFSAR Section 10.4.9, "Auxiliary Feedwater System," and WBN System Description N3-3B-4002, "Auxiliary Feedwater System." Included in these are General Design Criteria (GDC) of 10 CFR 50 Appendix A, GDC 34, "Residual Heat Removal" and NRC Standard Review Plan (SRP)-10.4.9, "Auxiliary Feedwater System (PWR)." 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

The proposed amendment will modify the mode applicability for function 6(e) of TS Table 3.3.2-1 to clarify that the Auxiliary Feedwater start function upon trip of the TDMFW pumps is only required in Modes 1 and 2 when one or more TDMFW Pumps are operating. Therefore, 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. Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(q). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment. El-5

7.0 REFERENCES

WBN UFSAR Section 10.4.9, "Auxiliary Feedwater System" WBN System Description N3-3B-4002, "Auxiliary Feedwater System" NRC General Design Criteria (GDC) of 10 CFR 50 Appendix A, GDC 34 "Residual Heat Removal" NRC Standard Review Plan (SRP)-10.4.9, "Auxiliary Feedwater System (PWR)" E1-6

ENCLOSURE 2 WBN-TS-04-013 TS PAGE 3.3.-38 PROPOSED TECHNICAL SPECIFICATION PAGE MARK-UP

ESFAS Instrumentation 3.3.2 Table 3.3.2-1 (page 5 of 7)

     .:Replaze.                            with    .. :..                           Engineered Safety feature Actuation System Instruwentation Trip

.. ....... of..... ...... llTurbine Driven Mai APPLICABLE KODES OR

             .Feedwaterpumps                                                                        OTHER NOIUAL SPECIFIED                           REOUIRED                                                          SURVEI LLANCE                                      ALLOUABLE                           TRIP CONDItIONS                           CHANNELS                       CONDITIONS                         REOUIREKEMTS                                             VALUE                    SETPOINT FUINCTI 0U

6. Auxiliary Feedwater Ccontirued)

c. Safety Injection Refer to Function 1 CSafety Injection) for all initiation fuwctiora and requirements

d. Loss of OffsIte 1.2.3 4 per F Refer to Function 4 of Table 3.3.5-1 for Power bus SRs and Allowable Values J SR 3.3.2.8 > 48 psig So psig

e. rip of ell 4ain j 1 per IFeedwater Pumps pu3p SR 3.3.2.9 SR 3.3.2.10

f. Auxiliary 1Z.3 F SR 3.3.2.6 A) i 0.5 A) 1.2 I Feedwater Puzips SR 3.3.2.9 psig psig Train A and B SR 3.3.2.10 Suction Transfer B) > 1.33 8) 2.0 psig psig on Suction Pressure -Low

    .Replace
      .. .. ........ ......              with:....             :                 /

I

             - j-{.....-i.t.... ...:..
    ..... .:.:.:.....                 2 : :.a

7. Automatic Switchover to Contairssent Sump R. Automatic 1,2,3,4 2 trains C SR 3.3.2.2 NA NA Actuation Logic SR 3.3.2.3 and Actuation SR 3.3.2.5 Relays (continued)

V .. . .. ......... .. .. ......

                                                      .. .. o..........-ir--eq t0r';-pl   ............s..

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                                                                                                                                                                                                         ............   .......... I...........

Watts Bar-Unit 1 3 .3-38 Amendmen t No. I

ENCLOSURE 3 W'BN-TS-04-013 TS PAGE 3.3-38 PROPOSED TECHNICAL SPECIFICATION TYPED PAGES

ESFAS Instrumentation 3.3.2 Table 3.3.2-1 (page 5 of 7) Engineered Safety Feature Actuation System Instrumentation APPLICABLE MODES NOMINAL OR OTHER SPECIFIED REQUIRED SURVEILLANCE ALLOWABLE TRIP FUNCTION CONDITIONS CHANNELS CONDITIONS REQUIREMENTS VALUE SETPOINT

6. Auxiliary Feedwater (continued)

c. Safety Refer to Function I (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(a).2(2) 1 per J SR 3.3.2.8 2 48 psig 50 psig Turbine Driven pump SR 3.3.2.9 Main Feedwater SR 3.3.2.10 Pumps

f. Auxiliary 1, 2,3 3 F SR3.3.2.6 A) 20.5 A) 1.2 Feedwater SR 3.3.2.9 psig psig Pumps SR 3.3.2.10 Train A and B B) 2 1.33 B) 2.0 Suction Transfer psig psig 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 Logic SR 3.3.2.3 and Actuation SR 3.3.2.5 Relays (continued)

(a) Not required unless one or more turbine driven main feedwater pumps are operating. Watts Bar-Unit 1 3 .3-38 Amendment 1

ENCLOSURE 4 WBN-TS-04-013 TECHNICAL SPECIFICATION BASES PAGE B 3.3-93 INFORMATION ONLY

ESFAS Instrumentation B 3.3.2 BASES APPLICABLE e. Auxiliary Feedwater-Trip Of All Main Feedwater SAFETY ANALYSES, Pumps LCO, and APPLICABILITY A Trip of both turbine driven MFW pumps is an (continued) indication of a loss of MFW and the subsequent need for some method of decay heat and sensible heat removal to bring the reactor back to no load temperature and pressure. A turbine driven MFW pump is equipped with one pressure switch on the control oil line for the speed control system. A low pressure signal from this pressure switch indicates a trip of that pump. A trip of both turbine driven MFW pumps starts the motor driven and turbine driven AFW pumps to ensure that enough water is available to act as the heat sink for the reactor.

                                                     'T   sencti on         m OPERA               M ODES I ie s ens rsfat at, les                 ne SG isw5ided with w      'o serve, 'te heat se'to remv>'
                                                          >n ncr;          In MODES 3, 4, and 5, the RCPs and MFW pumps may be normally shut down, and thus neither pump trip is indicative of a condition requiring automatic AFW initiation.

f. Auxiliary Feedwater-Pump Suction Transfer on Suction Pressure-Low I A low pressure signal in the AFW pump suction line protects the AFW pumps against a loss of the normal supply of water for the pumps, the CST.

Three pressure switches are located on each motor driven AFW pump suction line from the CST. A low I pressure signal sensed by two switches of a set will cause the emergency supply of water for the respective pumps to be aligned, ERCW (safety I

          -. -        ...   ............           a      w it ::                 ..........         ie turbine.drivenmn  ........... ..          e...m              are p a i in (es .....             with the Sintent of'op'eratinig).S'--n'.the 'case ofoetrie rvnmi
     .feedwater
         .. p p operatio                           t.....r..   ..........
                                                                       .ct o t.;.n pump must also be opera1';: This antipaoy                             '    funci 'n           is notr

,the.-safet-y .gra.decircuit..c.redi.tedin eit trr analyses'. but.. doe.s.. ensure that,atlest one Su is .ove i h  ; water..to. serve.as ..the. heatnsink Co remove reaor e et and sensibleheatintheevent of anaccident. I continued Watts Bar-Unit I B 3.3-93 Revision 2 Amendment No. 1}}