L-2011-431, Response to NRC Nuclear Performance and Code Review Branch Request for Additional Information Regarding Extended Power Uprate License Amendment Request No. 205
| ML11290A202 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 10/12/2011 |
| From: | Kiley M Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2011-431 | |
| Download: ML11290A202 (8) | |
Text
Florida Power & Light, 9760 S.W. 344 St. Homestead, FL 33035 0 OCT 122011 FPL. L-2011-431 10 CFR 50.90 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555-0001 Re: Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 Response to NRC Nuclear Performance and Code Review Branch Request for Additional Infonrmation Regarding Extended Power Uprate License Amendment Request No. 205
References:
(1) M. Kiley (FPL) to U.S. Nuclear Regulatory Commission (NRC) (L-2010-113), "License Amendment Request for Extended Power Uprate (LAR-205)," (TAC Nos. ME4907 and ME4908), Accession No. ML103560169, October 21, 2010.
(2) Email from J. Paige (NRC) to T. Abbatiello (FPL), "Turkey Point EPU - Nuclear Performance and Code Review (SNPB) Request for Additional Information - Round 1.2 (Part 2)," Accession No. ML11111A150, April 19, 2011.
(3) M. Kiley (FPL) to U.S. Nuclear Regulatory Commission (L-2011-170), "Response to NRC Request for Additional Information Regarding Extended Power Uprate License Amendment Request No. 205 and Nuclear Performance and Code Review Issues," Accession No. ML11143A010, May 19, 2011.
(4) M. Kiley (FPL) to U.S. Nuclear Regulatory Commission (L-2011-278), "Response to NRC Request for Additional Information Regarding Extended Power Uprate License Amendment Request No. 205 and Nuclear Performance and Code Review (SNPB) Issues," Accession No. ML11214A103, July 29, 2011.
(5) Email from J. Paige (NRC) to S. Hale (FPL) "Turkey Point EPU - Nuclear Performance and Code Review (SNPB) Request for Additional Information - Round 2.2 (Part 2)," Accession No. ML11236A286, August 24, 2011.
(6) M. Kiley (FPL) to U.S. Nuclear Regulatory Commission (L-2011-350), "Response to NRC Request for Additional Information Regarding Extended Power Uprate License Amendment Request No. 205 and Nuclear Perfonrmance and Code Review (SNPB) Issues," September 14, 2011.
(7) M. Kiley (FPL) to U.S. Nuclear Regulatory Commission (L-2011-415), "Response to NRC Nuclear Performance and Code Review Branch Request for Additional Information Regarding Extended Power Uprate License Amendment Request No. 205,"September 30, 2011.
By letter L-2010-113 dated October 21, 2010 [Reference 1], Florida Power and Light Company (FPL) requested to amend Renewed Facility Operating Licenses DPR-31 and DPR-41 and revise Turkey Point Units 3 and 4 Technical Specifications (TS). The proposed amendment will increase each unit's licensed core power level from 2300 megawatts thermal (MWt) to 2644 MWt and revise the Renewed Facility Operating Licenses and TS to support operation at this increased core thermal power level. This represents an approximate increase of 15% and is therefore considered an extended power uprate (EPU).
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Turkey Point Units 3 and 4 L-2011-431 Docket Nos. 50-250 and 50-251 Page 2 of 3 By email dated April 19, 2011 [Reference 2], the NRC Project Manager (PM) requested additional information to support the continued review of the EPU LAR by NRC staff in the Nuclear Performance and Code Review Branch (SNPB). The RAI consisted of five questions regarding detailed technical inputs and design information related to the EPU boron precipitation analysis.
FPL responded to the NRC requests via letter L-2011-170, dated May 19, 2011 [Reference 3].
During an NRC audit of the calculations for the PTN boric acid precipitation analyses held on July 11, 2011, the NRC requested additional information pertaining to assumptions and modeling techniques used in the PTN boric acid precipitation analysis. FPL provided the requested information in letter L-2011-278, dated July 29, 2011 [Reference 4].
By email dated August 24, 2011 [Reference 5], the NRC PM provided a follow-up RAI to FPL's response in Reference 3. The RAI consisted of one question with five parts, pertaining to redundancies available in PTN's safety injection system and to probabilistic risk assessment (PRA) modeling details of long tern core cooling with repeated transitions between hot leg and cold leg recirculation. FPL provided the requested information in letter L-2011-350, dated September 14, 2011 [Reference 6]. As a supplement to the information in Reference 4, FPL also provided responses to additional questions in Reference 6 that were based on information from the Point Beach EPU project including discussions on single failure, analysis conservatisms, precipitation during small break loss of coolant accidents (SBLOCA), and cooldown-induced precipitation.
During a follow-up NRC audit of the calculations for the PTN boric acid precipitation analysis held on September 20, 2011, the NRC requested further information pertaining to assumptions and modeling techniques. FPL provided responses to the additional questions in letter L-201 1-415, dated September 30, 2011 [Reference 7]. During subsequent telephone conferences conducted between FPL and NRC staff on September 27 and 29, 2011, the NRC requested additional information related to cold leg to hot leg switchover. FPL's response to the NRC's request is presented in the Attachment to this letter.
This submittal does not alter the significant hazards consideration or environmental assessment previously submitted by FPL letter L-2010-113 [Reference 1].
This submittal contains no new commitments and no revisions to existing commitments.
In accordance with 10 CFR 50.91(b)(1), a copy of this letter is being forwarded to the State Designee of Florida.
Should you have any questions regarding this submittal, please contact Mr. Robert J. Tomonto, Licensing Manager, at (305) 246-7327.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on October 2011.
Very truly yours, Michael Kiley Site Vice President Turkey Point Nuclear Plant
Turkey Point Units 3 and 4 L-2011-431 Docket Nos. 50-250 and 50-251 Page 3 of 3 Attachment cc: USNRC Regional Administrator, Region II USNRC Project Manager, Turkey Point Nuclear Plant USNRC Resident Inspector, Turkey Point Nuclear Plant Mr. W. A. Passetti, Florida Department of Health
Turkey Point Units 3 and 4 L-2011-431 Docket Nos. 50-250 and 50-251 Attachment Page 1 of 5 Turkey Point Units 3 and 4 RESPONSE TO NRC NUCLEAR PERFORMANCE AND CODE REVIEW BRANCH REQUEST FOR ADDITIONAL INFORMATION REGARDING EPU LAR NO. 205 ATTACHMENT RAI RESPONSE
Turkey Point Units 3 and 4 L-2011-431 Docket Nos. 50-250 and 50-251 Attachment Page 2 of 5 Response to Request for Additional Information The following information is provided by Florida Power and Light Company (FPL) in response to the U. S. Nuclear Regulatory Commission's (NRC) Request for Additional Information (RAI).
This information was requested to support License Amendment Request (LAR) 205, Extended Power Uprate (EPU), for Turkey Point Nuclear Plant (PTN) Units 3 and 4 that was submitted to the NRC by FPL via letter (L-2010-113) dated October 21, 2010 [Reference 1].
By email dated April 19, 2011 [Reference 2], the NRC Project Manager (PM) requested additional information to support the continued review of the EPU LAR by NRC staff in the Nuclear Performance and Code Review Branch (SNPB). The RAI consisted of five questions regarding detailed technical inputs and design information related to the EPU boron precipitation analysis.
FPL responded to the NRC requests via letter L-2011-170, dated May 19, 2011 [Reference 3].
During an NRC audit of the calculations for the PTN boric acid precipitation analyses held on July 11, 2011, the NRC requested additional information pertaining to assumptions and modeling techniques used in the PTN boric acid precipitation analysis. FPL provided the requested information in letter L-2011-278, dated July 29, 2011 [Reference 4].
By email dated August 24, 2011 [Reference 5], the NRC PM provided a tbllow-up RAI to FPL's response in Reference 3. The RAI consisted of one question with five parts, pertaining to redundancies available in PTN's safety injection system and to probabilistic risk assessment (PRA) modeling details of long term core cooling with repeated transitions between hot leg and cold leg recirculation. FPL provided the requested information in letter L-2011-350, dated September 14, 2011 [Reference 6]. As a supplement to the information in Reference 4, FPL also provided responses to additional questions in Reference 6 that were based on information from the Point Beach EPU project including discussions on single failure, analysis conservatisms, precipitation during small break loss of coolant accidents (SBLOCA), and cooldown-induced precipitation.
During a follow-up NRC audit of the calculations for the PTN boric acid precipitation analysis held on September 20, 2011, the NRC requested further information pertaining to assumptions and modeling techniques. FPL provided responses to the additional questions in letter L-201 1-415, dated September 30, 2011 [Reference 7].
During subsequent telephone conferences conducted between FPL and NRC staff on September 27 and 29, 2011, the NRC requested additional information regarding the timing required to transfer safety injection flow from the cold legs to the hot legs following an assumed Large Break Loss of Coolant Accident (LBLOCA). Specifically, the NRC requested that FPL provide additional discussion of margins between the maximum time allowed for this switchover in the operating procedures (3 minutes) and the analytically determined time for core uncovery (3.77 minutes).
The NRC stated that the items to be discussed in the response should include actual time to core uncovery based on a more realistic decay heat model, valve open and close stroke times, pump start and stop times, actual operator performance, operator actions if a problem were to occur during the switch over, time to terminate boiling, and actions to secure the plant for the long tenn.
Turkey Point Units 3 and 4 utilize high pressure High-Head Safety Injection Pumps for cold leg and hot leg recirculation. For the Extended Power Uprate (EPU), there will be two High-Head Safety Injection Pumps injecting into the cold legs during cold leg recirculation, and two High-Head Safety Injection Pumps injecting into the hot legs during hot leg recirculation. During this phase of a LBLOCA, the High-Head Safety Injection Pumps take suction from the discharge of one Residual Heat Removal System (RHRS) pump which is aligned to the sump in what is
Turkey Point Units 3 and 4 L-2011-431 Docket Nos. 50-250 and 50-251 Attachment Page 3 of 5 termed "piggy-back" operation. Due to pump run-out, net positive suction head (NPSH), and pump recirculation flow limitations, the High-Head Safety Injection Pumps are stopped and restarted during the transfer from cold leg recirculation to hot leg recirculation.
The switchover from cold leg recirculation to hot leg recirculation is performed in accordance with the emergency operating procedure (EOP) for transfer to hot leg recirculation. The procedural steps to perform the switchover are as follows:
- 1. Stop High-Head Safety Injection Pumps
- 2. Open both loop Hot Leg Safety Injection Valves
- 3. Close both Safety Injection to Cold Leg Isolation Valves
- 4. Start High-Head Safety Injection Pumps The total time for the above valves to stroke open and close and the pumps to start and stop based on data from pump and valve testing is less than one minute. Also, actual simulator validation of the emergency operating procedures for LBLOCA has demonstrated that operators can accomplish these steps in less than two minutes. If at any point during the transfer, a specific equipment response is not obtained, the EOPs instruct the operators to restore cold leg injection either with the High Head Safety Injection Pumps or the Residual Heat Removal pumps. Under EPU conditions, with the elimination of the concurrent hot leg and cold leg recirculation lineup, no single active failure will prevent the transition to hot leg recirculation [Reference 6].
Prior to interrupting core cooling there is an operational caution statement in the EOPs to alert the operations staff of the need to limit the interruption of Emergency Core Cooling System (ECCS) flow to the core. An assessment of the time to core uncovery using both Appendix K and realistic decay heat models has been performed and is documented in Table 1 below.
Table 1 Assessment of the Interruption of ECCS at the Transfer to Hot Leg Recirculation Operator 1 )A EOP( 2 Appendix K(33 RealisticO) Margint 5)
Action Interruption <2 min. <3 min. 3.77 min. 7.3 min. >5.3 min.
Time (1) Based on simulator evolutions.
(2) Conservatively chosen operator action based on simulator evolutions.
(3) Calculated using 1971 ANS infinite + 20% decay heat.
(4) Calculated using 1971 ANS finite decay heat without uncertainty.
(5) Margin = Realistic - Operator Action Based on the results, the time to core uncovery using realistic decay heat is 7.3 minutes after the termination of ECCS flow to the cold legs which provides >5.3 minutes of margin between actual operator performance on the simulator and the realistic calculated time to core uncovery.
Note that the margin summarized above does not include the time from core uncovery to the point where the fuel would heat up and reach 2200TF. This would add approximately 1247 seconds (20 minutes 47 seconds) to the margin noted above.
The amount of time needed to terminate boiling in the core following a LOCA is very much dependent on a number of parameters including break size, break location, ECCS injection location, type and number of ECCS pumps in operation, decay heat, and EOP instructions. Also, under post-LOCA circumstances, the Techmical Support Center (TSC) and Emergency Operations
Turkey Point Units 3 and 4 L-2011-431 Docket Nos. 50-250 and 50-251 Attachment Page 4 of 5 Facility (EOF) would be providing specific recommendations, in addition to the EOPs, to Control Room operators to ensure that the plant is brought to a safe and stable condition including the termination of boiling. These recommendations would be based on a number of factors including indications from monitoring instrumentation for the Reactor Coolant System and Containment, onsite and offsite dose, the status and capability of various systems and components, and the availability of offsite power.
The time required to terminate core boiling was estimated for several potential combinations of the above parameters. Note that time to terminate boiling was not estimated for some of the combinations due to significant uncertainty in parameters such as bypass flow during hot leg recirculation with a hot leg break.
For combinations estimated, ranges of time to terminate core boiling are presented in Table 2 below:
Table 2 Time to Terminate Boiling Time to Terminate Boiling Assuming Nominal Decay Heat(') Assuming Appendix K Decay Heat(')
0°F Core Exit 30'F Core Exit 0°F Core Exit 30'F Core Exit Subcooling (days) Subcooling (days) Subcooling (days) Subcooling (days) 6-16 18-55 13-60 69->232 Note:
I. RHR heat exchanger outlet temperature assumed to be 150'F and system pressure assumed to be 14.7 psia for all cases.
Finally, to secure the plant for the long term, plant operators would consult with the TSC and EOF on what appropriate long term actions need to be taken to bring the plant to a safe, cold shutdown condition. As noted above, the decisions regarding these actions would be based on a number of factors including indications from monitoring instrumentation for the Reactor Coolant System and Containment, onsite and offsite dose, the status and capability of various systems and components, and the availability of offsite power.
References I. M. Kiley (FPL) to U.S. Nuclear Regulatory Commission (L-2010-1 13), "License Amendment Request for Extended Power Uprate (LAR 205)," (TAC Nos. ME4907 and ME4908),
Accession No. ML103560169, October 21, 2010.
- 2. Email from J. Paige (NRC) to T. Abbatiello (FPL), "Turkey Point EPU - Nuclear Performance and Code Review (SNPB) Request for Additional Information - Round 1.2 (Part 2)," Accession No. ML 111 1A150, April 19, 2011.
- 3. M. Kiley (FPL) to U.S. Nuclear Regulatory Commission (L-2011-170), "Response to NRC Request for Additional Information Regarding Extended Power Uprate License Amendment Request No. 205 and Nuclear Performance and Code Review Issues," Accession No. ML 1 143A010, May 19, 2011.
- 4. M. Kiley (FPL) to U.S. Nuclear Regulatory Commission (L-2011-278), "Response to NRC Request for Additional Information Regarding Extended Power Uprate License Amendment Request No. 205 and Nuclear Performance and Code Review (SNPB) Issues," Accession No. ML11214A103, July 29, 2011.
Turkey Point Units 3 and 4 L-2011-431 Docket Nos. 50-250 and 50-251 Attachment Page 5 of 5
- 5. Email from J. Paige (NRC) to S. Hale (FPL) "Turkey Point EPU - Nuclear Performance and Code Review (SNPB) Request for Additional Information - Round 2.2 (Part 2)," Accession No. ML11236A286, August 24, 2011.
- 6. M. Kiley (FPL) to U.S. Nuclear Regulatory Commission (L-2011-350), "Response to NRC Request for Additional Information Regarding Extended Power Uprate License Amendment Request No. 205 and Nuclear Performance and Code Review (SNPB) Issues," September 14, 2011.
- 7. M. Kiley (FPL) to U.S. Nuclear Regulatory Commission (L-2011-415), "Response to NRC Nuclear Performance and Code Review Branch Request for Additional Information Regarding Extended Power Uprate License Amendment Request No. 205," September 30, 2011.