ML13358A083
| ML13358A083 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 12/20/2013 |
| From: | Borton K Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML13358A083 (23) | |
Text
10 CFR 50.90 December 20, 2013 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Peach Bottom Atomic Power Station, Units 2 and 3 Facility Operating License Nos. DPR-44 and DPR-56 NRC Docket Nos. 50-277 and 50-278 Extended Power Uprate License Amendment Request-Supplement 16 Corrections, Clarifications and Additional Information - Extended Power Up rate
Reference:
- 1.
Letter from K. F. Borton (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission "License Amendment Request-Extended Power Uprate," dated September 28, 2012 (ADAMS Accession No. ML122860201)
- 2.
Letter from K. F. Borton (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "Supplemental Information Supporting Request for License Amendment Request-Supplement 5," dated June 27, 2013 (ADAMS Accession No. ML13156A368)
In accordance with 10 CFR 50.90, Exelon Generation Company, LLC (EGC) requested amendments to Facility Operating License Nos. DPR-44 and DPR-56 for Peach Bottom Atomic Power Station (PBAPS) Units 2 and 3, respectively (Reference 1). Specifically, the proposed changes would revise the Renewed Operating Licenses to implement an increase in rated thermal power from 3514 megawatts thermal (MWt) to 3951 MWt.
The attachments to this letter provide responses to follow-up questions resulting from the Health Physics and Human Performance Branch (AHPB) review of Reference 2 as well as corrections and clarifications to the information provided in Reference 1.
The attachments to this supplement are summarized as follows: - Exelon responses to AHPB RAI-8, 9 and 10. -This attachment corrects errors in the description of monitoring locations in 3, Tables 3-1, 3-2, 3-3, 3-4 and 3-5 of Reference 1.
Specifically, the errors involved the description nomenclature that mistakenly used information from the other unit. The actual monitoring locations are unchanged with the exception of one Unit 2 location (Support
U. S. Nuclear Regulatory Commission EPU LAR Supplement 16 Corrections, Clarifications and Additional Information December 20, 2013 Page2 6DD-H10 in Table 3-2). In this case, the Unit 2 monitoring location is slightly different than the Unit 3 monitoring location due to differences in the dead weight support configurations. The analyses and resulting acceptance criteria as described in Attachment 13 are unaffected by these changes. Replacement Tables 3-1, 3-2, 3-3, 3-4 and 3-5 are provided. - This attachment provides replacement pages that supersede Technical Specification page 3.3-7 for Unit 2 and Unit 3 contained in Reference 1, (Revised Tech Spec Pages). Specifically, in Insert B, note (e), the word "predetermined" was changed to "predefined" to be consistent with Attachment 1 to Reference 1 and TSTF-493 and capitalization of the word "in" was corrected in note (f). - This attachment provides a clarification to the descriptions in Attachment 9 and Enclosure 9b to Reference 1 of the purpose of the EPU modification that increases the isotopic enrichment of the Boron-1 0 (B-1 0) in the Standby Liquid Control (SLC) System sodium pentaborate (SPB) solution.
EGC has reviewed the information supporting a finding of no significant hazards consideration and the environmental consideration provided to the U. S. Nuclear Regulatory Commission in Reference 1. The supplemental information provided in this submittal does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration. Further, the additional information provided in this submittal does not affect the bases for concluding that neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed amendment.
In accordance with 10 CFR 50.91, "Notice for public comment; State consultation,"
paragraph (b), EGC is notifying the Commonwealth of Pennsylvania and the State of Maryland of this application by transmitting a copy of this letter along with the attachments to the designated State Officials.
There are no regulatory commitments contained in this letter.
Should you have any questions concerning this letter, please contact Mr. David Neff at (61 0) 765-5631.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 20th day of December 2013.
Respe~
~~
Kevin F. Borton Manager, Licensing - Power Uprate Exelon Generation Company, LLC
U. S. Nuclear Regulatory Commission EPU LAR Supplement 16 Corrections, Clarifications and Additional Information December 20, 2013 Page 3 Attachments:
- 1. Responses to Health Physics and Human Performance Branch RAI-8, 9 and 10
- 2. Corrections to EPU LAR Attachment 13 (Flow Induced Vibration)
- 4. Clarification to EPU LAR Enclosure 9b (Standby Liquid Control System Modifications) cc:
USNRC Region I, Regional Administrator w/attachments USNRC Senior Resident Inspector, PBAPS w/attachments USNRC Project Manager, PBAPS w/attachments R. R. Janati, Commonwealth of Pennsylvania w/attachments S. T. Gray, State of Maryland w/attachments
Peach Bottom Atomic Power Station Units 2 and 3 NRC Docket Nos. 50-277 and 50-278 Responses to Health Physics and Human Performance Branch RAI-8, 9 and 10
EPU LAR Supplement 16 Responses to AHPB RAI 8, 9 and 10 Page 1 Response to Request for Additional Information Health Physics and Human Performance Branch By letter dated September 28, 2012, Exelon Generation Company, LLC (EGC) submitted a license amendment request for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.
The proposed amendment would authorize an increase in the maximum power level from 3514 megawatts thermal (MWt) to 3951 MWt. The requested change, referred to as an extended power uprate (EPU), represents an increase of approximately 12.4 percent above the current licensed thermal power level. Supplement 5 to the license amendment request, submitted to the NRC on June 27, 2013, (ADAMS Accession No. ML13156A368) included Attachment 4 which provided a revision to Reference 1, Attachments 4 and 6, Section 2.11, Human Performance. In an email dated November 1, 2013, from the NRC (Rick Ennis) to Exelon (Kevin Borton and Dave Neff), the NRC provided additional RAIs seeking clarification of certain issues related to Attachment 4 to Supplement 5. This attachment provides responses to those RAIs.
AHPB RAI-8 As discussed on page 4 of Attachment 4 to Supplement 5 dated June 27, 2013, as part of the containment accident pressure credit elimination strategy, operators will manage entry into alternate shutdown cooling (ASDC), when required, to ensure that suppression pool temperature remains below the limit needed to maintain adequate net positive suction head for operating the emergency core cooling pumps. This will be accomplished by providing guidance in the ASDC procedure "for the operator to anticipate a 10 °F rise in suppression pool temperature upon initiation of ASDC." There is no additional information as to how the operator might verify that this rise in temperature is or is not happening. Please provide information as to what cues the operator will use to anticipate this rise, along with what indications or displays will show this temperature change.
RESPONSE
The 10 °F temperature rise is an anticipated value and the procedures will prepare the operator to expect a conservative suppression pool (SP) temperature rise when ASDC is initiated.
Existing procedures for reactor depressurization and implementation of ASDC will be used by the operators and employ the use of safety grade main control room instruments for monitoring reactor pressure, SP temperature and SP level prior to and during ASDC operation.
The existing procedure guidance will be enhanced to use these parameters in conjunction with a new curve for determining the expected SP temperature rise based on the reactor pressure and the SP water level. The procedures will include the following enhanced guidance:
- 1. Determine SP temperature prior to initiation of ASDC.
- 2. Determine the anticipated rise in SP temperature (based on reactor pressure) using the new curve.
- 3. Add the anticipated rise in SP temperature to current SP temperature to determine the anticipated maximum SP temperature.
EPU LAR Supplement 16 Responses to AHPB RAI 8, 9 and 10 Page 2
- 4. Plot the maximum anticipated SP temperature on emergency core cooling system (ECCS) pump net positive suction head (NPSH) curve in the emergency operating procedure.
- 5. If adequate ECCS pump NPSH is available, initiate ASDC; if not, delay ASDC initiation and re-perform the previous steps after SP temperature has been lowered.
The enhanced procedural guidance will ensure that operators verify that adequate ECCS pump NPSH margin exists prior to initiating ASDC.
AHPB RAI-9 Please provide information on the verification and validation process used to evaluate the timing analyses for the new or changed operator actions.
RESPONSE
New and changed operator actions for both the design basis accidents (DBAs) and Special Events were evaluated for EPU LAR purposes consistent with the requirements of the Peach Bottom Operator Response Time Program. The process compared the time when the action is required to the expected performance times. Validation methods for the expected performance times are from simulator runs, plant walkthroughs, or benchmarking against other existing operator actions that were previously validated by simulator runs and walkthroughs. The sequencing of the actions and number of operators available were factored into the evaluation.
Implementation of EPU will include updating of the associated EOPs, training, and the Operator Response Time Program, including updates to the Master List of Time Critical and Time Sensitive Actions.
This evaluation was documented in accordance with the EGC Configuration Change Process and included cross-discipline reviews from a Senior Reactor Operator and Engineering.
AHPB RAI-10 As discussed on page 4 of Attachment 4 to Supplement 5 dated June 27, 2013, fire safe shutdown Method D was reviewed using the plant simulator. It is not clear whether all of the Methods were reviewed using the simulator as well. If they were not, please provide justification.
RESPONSE
A proposed reduction in operator action time for initiation of ASDC for FSSD Method D was verified in the simulator as part of EPU analysis for CAP credit elimination. A review of the operator action timeline analyses for Methods A/B/C in the FSSD calculations for the EPU analysis determined that there were no fire areas where operator availability or time constraints would prevent completion of required actions in accordance with the revised response times.
Therefore, no additional verification of operator timelines in the plant or in the simulator was necessary.
Peach Bottom Atomic Power Station Units 2 and 3 NRC Docket Nos. 50-277 and 50-278 Corrections to EPU LAR Attachment 13 (Flow Induced Vibration)
Page 5 Table 3-1 Drywell EPU Monitoring Locations for MS and FW, PBAPS Unit 2 System Location1 Direction Allowable Peak-to-Peak Displacement, mils Description MS 4
X 48 At support M2191-2-HB3, in the X (north-south) and Z (east-west) directions.
MS 4
Z 32 MS 10J X
24 At support M2191-2-HB4 in the X (north-south), Y (vertical) direction and Z (east-west) directions.
MS 10J Y
16 MS 10J Z
22 MS 80 X
22 At support M2191-2-HA3 in the X (north-south), Y (vertical) and Z (east-west) directions MS 80 Y
38 MS 80 Z
24 MS 15 X
26 At support M2191-2-HA1 in the X (north-south), and Z (east-west) directions.
MS 15 Z
94 FW 400 X
252 At pipe support 6DDNL-H33, in the X (east-west), Y (vertical), and Z (north-south) directions.
FW 400 Y
278 FW 400 Z
272 FW 200 X
143 At pipe support 6DDNL-H42, in the X (east-west), Y (vertical), and Z (north-south) directions.
FW 200 Y
40 FW 200 Z
90 Note (1): Since the Unit 2 and 3 piping geometries are similar, only the Unit 3 piping was modeled. Therefore, the Unit 2 locations are identified with the corresponding Unit 3 node numbers.
H41 M2194 M2194 M2194 M2194
Page 6 Table 3-2 Turbine Building EPU Monitoring Locations for MS and FW, PBAPS Unit 2 System Location1 Direction Allowable Peak-to-Peak Displacement, mils Description MS 24 X
500 At support IDB-H10, in the X (north-south) direction, Y (vertical) direction, and Z (east-west) direction MS 24 Y
130 MS 24 Z
284 MS 52 X
190 At support IDB-H33, in the X (north-south) direction, Y (vertical) direction, and Z (east-west) direction MS 52 Y
234 MS 52 Z
202 MS 942 X
284 At the low point drain line branch connection to the turbine lead, in the X (north-south) direction and Z (east-west) direction.
MS 942 Z
500 MS 78 X
136 At support IDB-H77, in the X (north-south) direction and Y (vertical) direction MS 78 Y
216 MS 922 X
126 At the low point drain line branch connection to the turbine lead, in the X (north-south) direction and Z (east-west) direction.
MS 922 Z
500 FW 59 Y
294 At support 2-6DD-S2, in the Y (vertical) and Z (east-west) directions FW 59 Z
276 FW 175 X
306 At support 2-6DD-H71 in the X (north-south) and Y (vertical) directions FW 175 Y
398 FW 310 Y
336 At support 2-6DD-H15 in the Y (vertical) and Z (east-west) directions FW 310 Z
330 1DB 1DB 7DB CV2 CV4 6DD 6DD-H10 6DD
Page 7 FW 435 X
216 At support 2-18GF-H372, in the X (north-south) and Z (east-west) directions FW 435 Z
286 Note 1: Since the Unit 2 and 3 piping geometries are similar, only the Unit 3 piping was modeled. Therefore, the Unit 2 locations are identified with the corresponding Unit 3 node numbers.
18GF
Page 8 Table 3-3 Drywell EPU Monitoring Locations for MS and FW, PBAPS Unit 3 System Location Direction Allowable Peak-to-Peak Displacement, mils Description MS 4
X 48 At support M2191-3-HB3, in the X (north-south) and Z (east-west) directions.
MS 4
Z 32 MS 10J X
24 At support M2191-3-HB4 in the X (north-south), Y (vertical) direction and Z (east-west) directions.
MS 10J Y
16 MS 10J Z
22 MS 80 X
22 At support M2191-3-HA3 in the X (north-south), Y (vertical) and Z (east-west) directions.
MS 80 Y
38 MS 80 Z
24 MS 15 X
26 At support M2191-3-HA1 in the X (north-south), and Z (east-west) directions MS 15 Z
94 FW 400 X
252 At pipe support 3-6DDNL-H33, in the X (east-west), Y (vertical), and Z (north-south) directions FW 400 Y
278 FW 400 Z
272 FW 200 X
143 At pipe support 3-6DDNL-H42, in the X (east-west), Y (vertical), and Z (north-south) directions.
FW 200 Y
40 FW 200 Z
90 H41
Page 9 Table 3-4 Turbine Building EPU Monitoring Locations for MS and FW, PBAPS Unit 3 System Location Direction Allowable Peak-to-Peak Displacement, mils Description MS 24 X
500 In the X (north-south) direction, Y (vertical) direction, and Z (east-west) direction, at support 3-IDB-H10 MS 24 Y
130 MS 24 Z
284 MS 52 X
190 In the X (north-south) direction, Y (vertical) direction, and Z (east-west) direction, at support 3-IDB-H33 MS 52 Y
234 MS 52 Z
202 MS 942 X
284 In the X (north-south) direction and Z (east-west) direction, at the low point drain line branch connection to the turbine lead MS 942 Z
500 MS 78 X
136 In the X (north-south) direction and Y (vertical) direction, at support 3-IDB-H77 MS 78 Y
216 MS 922 X
126 In the X (north-south) direction and Z (east-west) direction, at the low point drain line branch connection to the turbine lead MS 922 Z
500 FW 59 Y
294 at support 3-6DD-S2, in the Y (vertical) and Z (east-west) directions FW 59 Z
276 FW 175 X
306 at support 3-6DD-H71 in the X (north-south) and Y (vertical) directions FW 175 Y
398 1DB 1DB CV1 7DB CV3
Page 10 FW 310 Y
336 at support 3-6DD-H15 in the Y (vertical) and Z (east-west) directions FW 310 Z
330 FW 435 X
216 at support 3-18GF-H372, in the X (north-south) and Z (east-west) directions FW 435 Z
286
Page 12 Table 3-5 Turbine Building EPU Monitoring Locations for CD, ES and HD, PBAPS Unit 2 System Location1 Direction Allowable Peak-to-Peak Displacement, mils Description CD 95 X
500 At support 2-18GFH-238 CD 95 Y
337 CD 95 Z
500 CD 930 X
417 At support 2-18GFH-261 CD 930 Y
172 CD 930 Z
389 ES 42 X
500 At support 2-16GA-H60 ES 42 Y
500 ES 42 Z
500 ES 23D X
397 At support 2-16GA-H51 ES 23D Y
329 ES 23D Z
500 ES 174 X
209 At Support 2-16HA-H33 ES 174 Y
305 ES 74 Y
231 At Support 2-16HA-H27 ES 74 Z
144 ES 117 X
500 At Support 2-16HA-H37 ES 117 Z
311 HD 110 X
500 At support 2-17GE-H9 HD 110 Z
500 17GF
Page 13 HD 140 Y
70 At support 2-17GE-394 HD 40 X
332 At support 2-17GE-H2 HD 40 Z
64 Note 1: Since the Unit 2 and 3 piping geometries are similar, only the Unit 3 piping was modeled. Therefore, the Unit 2 locations are identified with the corresponding Unit 3 node numbers.
Peach Bottom Atomic Power Station Units 2 and 3 NRC Docket Nos. 50-277 and 50-278 Corrections to EPU LAR Attachment 2 (Revised Tech Spec Pages)
RPS Instrumentation 3.3.1.1 Table 3.3.1.1-1 (page 1 of 3)
Reactor Protection System Instrumentation FUNCTION APPLICABLE MODES OR OTHER SPECIFIED CONDITIONS REQUIRED CHANNELS PER TRIP SYSTEM CONDITIONS REFERENCED FROM REQUIRED ACTION D.1 SURVEILLANCE REQUIREMENTS ALLOWABLE VALUE 1.
Wide Range Neutron Monitors a.
Period-Short 2
3 G
SR 3.3.1.1.1 SR 3.3.1.1.5 SR 3.3.1.1.12 SR 3.3.1.1.17 SR 3.3.1.1.18 13 seconds 5(a) 3 H
SR 3.3.1.1.1 SR 3.3.1.1.6 SR 3.3.1.1.12 SR 3.3.1.1.17 SR 3.3.1.1.18 13 seconds b.
Inop 2
5(a) 3 3
G H
SR 3.3.1.1.5 SR 3.3.1.1.17 SR 3.3.1.1.6 SR 3.3.1.1.17 NA NA 2.
Average Power Range Monitors a.
Neutron Flux-High (Setdown) 2 3(c)
G SR 3.3.1.1.1 SR 3.3.1.1.8 SR 3.3.1.1.11 SR 3.3.1.1.12 15.0% RTP b.
Simulated Thermal Power-High 1
3(c)
F SR 3.3.1.1.1 SR 3.3.1.1.2 SR 3.3.1.1.8 SR 3.3.1.1.11 SR 3.3.1.1.12 0.65 W
+ 63.7% RTP(b) and 118.0%
RTP c.
Neutron Flux-High 1
3(c)
F SR 3.3.1.1.1 SR 3.3.1.1.2 SR 3.3.1.1.8 SR 3.3.1.1.11 SR 3.3.1.1.12 119.7% RTP d.
Inop 1,2 3(c)
G SR 3.3.1.1.11 NA e.
2-Out-Of-4 Voter 1,2 2
G SR 3.3.1.1.1 SR 3.3.1.1.11 SR 3.3.1.1.17 SR 3.3.1.1.18 NA f.
OPRM Upscale 25%
RTP 3(c)
I SR 3.3.1.1.1 SR 3.3.1.1.8 SR 3.3.1.1.11 SR 3.3.1.1.12 SR 3.3.1.1.19 (d)
(continued)
(a)
With any control rod withdrawn from a core cell containing one or more fuel assemblies.
(b) 0.65 (W - W) + 63.7% RTP when reset for single loop operation per LCO 3.4.1, "Recirculation Loops Operating."
(c)
Each APRM channel provides inputs to both trip systems.
(d)
See COLR for OPRM period based detection algorithm (PBDA) setpoint limits.
PBAPS UNIT 2 3.3-7 Amendment No. 273 0.55 63.3 (e), (f) 0.55 61.5 Insert B 21.2
Section 3.3.1.1 Insert B (e)
If the as-found channel setpoint is outside its predefined as-found tolerance, then the channel shall be evaluated to verify that it is functioning as required before returning the channel to service.
(f)
The instrument channel set point shall be reset to a value that is within the Leave Alone Zone (LAZ) around the Nominal Trip Setpoint (NTSP) at the completion of the surveillance; otherwise, the channel shall be declared inoperable. Setpoints more conservative than the NTSP are acceptable provided the as-found tolerance and LAZ apply to the actual setpoint implemented in the Surveillance procedures to confirm channel performance. The NTSP methodologies used to determine the as-found tolerance and the LAZ are specified in the Bases associated with the specified function.
RPS Instrumentation 3.3.1.1 Table 3.3.1.1-1 (page 1 of 3)
Reactor Protection System Instrumentation FUNCTION APPLICABLE MODES OR OTHER SPECIFIED CONDITIONS REQUIRED CHANNELS PER TRIP SYSTEM CONDITIONS REFERENCED FROM REQUIRED ACTION D.1 SURVEILLANCE REQUIREMENTS ALLOWABLE VALUE 1.
Wide Range Neutron Monitors a.
Period-Short 2
3 G
SR 3.3.1.1.1 SR 3.3.1.1.5 SR 3.3.1.1.12 SR 3.3.1.1.17 SR 3.3.1.1.18 13 seconds 5(a) 3 H
SR 3.3.1.1.1 SR 3.3.1.1.6 SR 3.3.1.1.12 SR 3.3.1.1.17 SR 3.3.1.1.18 13 seconds b.
Inop 2
5(a) 3 3
G H
SR 3.3.1.1.5 SR 3.3.1.1.17 SR 3.3.1.1.6 SR 3.3.1.1.17 NA NA 2.
Average Power Range Monitors a.
Neutron Flux-High (Setdown) 2 3(c)
G SR 3.3.1.1.1 SR 3.3.1.1.8 SR 3.3.1.1.11 SR 3.3.1.1.12 15.0% RTP b.
Simulated Thermal Power-High 1
3(c)
F SR 3.3.1.1.1 SR 3.3.1.1.2 SR 3.3.1.1.8 SR 3.3.1.1.11 SR 3.3.1.1.12 0.65 W
+ 63.7% RTP(b) and 118.0%
RTP c.
Neutron Flux-High 1
3(c)
F SR 3.3.1.1.1 SR 3.3.1.1.2 SR 3.3.1.1.8 SR 3.3.1.1.11 SR 3.3.1.1.12 119.7% RTP d.
Inop 1,2 3(c)
G SR 3.3.1.1.11 NA e.
2-Out-Of-4 Voter 1,2 2
G SR 3.3.1.1.1 SR 3.3.1.1.11 SR 3.3.1.1.17 SR 3.3.1.1.18 NA f.
OPRM Upscale 25%
RTP 3(c)
I SR 3.3.1.1.1 SR 3.3.1.1.8 SR 3.3.1.1.11 SR 3.3.1.1.12 SR 3.3.1.1.19 (d)
(continued)
(a)
With any control rod withdrawn from a core cell containing one or more fuel assemblies.
(b) 0.65 (W - W) + 63.7% RTP when reset for single loop operation per LCO 3.4.1, "Recirculation Loops Operating."
(c)
Each APRM channel provides inputs to both trip systems.
(d)
See COLR for OPRM period based detection algorithm (PBDA) setpoint limits.
PBAPS UNIT 3 3.3-7 Amendment No. 277 0.55 63.3 21.2 0.55 61.5 (e), (f)
Insert B
Section 3.3.1.1 Insert B (e)
If the as-found channel setpoint is outside its predefined as-found tolerance, then the channel shall be evaluated to verify that it is functioning as required before returning the channel to service.
(f)
The instrument channel set point shall be reset to a value that is within the Leave Alone Zone (LAZ) around the Nominal Trip Setpoint (NTSP) at the completion of the surveillance; otherwise, the channel shall be declared inoperable. Setpoints more conservative than the NTSP are acceptable provided the as-found tolerance and LAZ apply to the actual setpoint implemented in the Surveillance procedures to confirm channel performance. The NTSP methodologies used to determine the as-found tolerance and the LAZ are specified in the Bases associated with the specified function.
Peach Bottom Atomic Power Station Units 2 and 3 NRC Docket Nos. 50-277 and 50-278 Clarification to EPU LAR Enclosure 9b (Standby Liquid Control System Modifications)
EPU LAR Supplement 16 Clarification to EPU LAR Enclosure 9b Page 1 and Enclosure 9b of the PBAPS EPU LAR currently state that one of the purposes of increasing the isotopic enrichment of the Standby Liquid Control (SLC)
System Boron-10 (B-10) sodium pentaborate (SPB) solution is to limit the suppression pool (SP) temperature to meet the inlet temperature restrictions for the High Pressure Coolant Injection (HPCI) and Reactor Core Isolation Cooling (RCIC) pumps. Although the increased B-10 SPB solution enrichment does reduce SP temperature, the statement is misleading. The design basis analysis for the Anticipated Transient Without SCRAM (ATWS) event assumes that the suction source for the HPCI and RCIC pumps during the ATWS event is the Condensate Storage Tank (CST) and not the SP. This is clearly stated in other sections of the EPU LAR (see Attachment 9 Section 3.2.3.2 and e Section 1.0). Therefore, the stated purpose of the B-10 modification related to HPCI and RCIC inlet temperature from the SP is removed as noted below.
Additions are indicated with bolded characters and deletions are indicated with strikethrough markers.
The clarified sections are provided below:
- 1. Attachment 9 Section 3.2.3.2 Page 11 In addition to the modifications discussed above that increase the NPSH margin for the ECCS pumps sufficient to preclude reliance on CAP, the SLC System Modifications (Enclosure 9b) also supports an increase in NPSH margin. The proposed change in B-10 enrichment is required to keep the suppression pool temperature within the limits of the ATWS analysis, described in PUSAR section 2.8.5.7 and to meet inlet temperature restrictions for the HPCI and RCIC pumps.
Since the increase in B-10 enrichment in the SLC system will facilitate a faster reactor shutdown during an ATWS event, it results in a reduced heat load input into the suppression pool. The reduction in the heat load reduces the peak suppression pool temperature which improves NPSH margin.
- 2. Enclosure 9b Section 1.0 Paragraph 1 Exelon Generation Company (EGC) is pursuing an Extended Power Uprate (EPU) of approximately 12.4 percent at the Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3. As part of the EPU, PBAPS proposes to increase the isotopic enrichment of the Boron-10 (B-10) in the Standby Liquid Control (SLC)
System sodium pentaborate (SPB) solution, which is the credited neutron absorber. Increasing the isotopic enrichment of B-10 in the SPB solution effectively increases the amount of B-10 in the SPB solution. This increases the potential rate of available negative reactivity in the SLC system and which when inserted into the core, results in a faster shut down of the reactor. A faster shut down reduces the amount of heat that is generated in the reactor and ultimately transferred to the suppression pool. The proposed change in B-10 enrichment is required to keep the suppression pool temperature within the limits in the Anticipated Transient Without Scram (ATWS) analysis, described in PUSAR section 2.8.5.7, Anticipated Transient Without Scram,. and to meet inlet temperature restrictions for the High Pressure Coolant Injection (HPCI) and Reactor Core Isolation Cooling (RCIC) pumps.
EPU LAR Supplement 16 Clarification to EPU LAR Enclosure 9b Page 2
- 3. Enclosure 9b Section 3.3 SLC system shutdown capability is discussed in Attachment 6, PUSAR Section 2.8.4.5, Standby Liquid Control System. SLC system shutdown capability is evaluated for each fuel reload. The boron shutdown concentration of 660 ppm does not change for EPU. Specifically, changes are not necessary to the SPB solution volume, the SPB concentration or B-10 enrichment for EPU to achieve the required reactor boron concentration for cold shutdown conditions and to comply with the ATWS rule in 10 CFR 50.62. However, the increase in the minimum B-10 enrichment from 61.92 atom percent to 92 atom percent for EPU is based B-10 on injection rate demands for the EPU ATWS analysis.. which maintains the pool temperature below design limits to meet inlet temperature restrictions for the HPCI and RCIC pumps and support increasing NPSH margin for the ECCS pumps.
- 4. Enclosure 9b Section 3.4 Paragraph 2
, PUSAR Section 2.8.5.7, demonstrates that PBAPS satisfies the boron injection equivalency requirement in 10 CFR 50.62. The equivalency requirement is satisfied at EPU power levels with the minimum SLC system pump flow rate of 49.1 gpm, the minimum concentration of 8.32 percent weight SPB, and the minimum B-10 enrichment of 92 atom percent. As shown in the PUSAR Section 2.8.5.7, the equivalency equation product is 1.69, which exceeds the requirement of 1.0. It is important to note that the use of the SLC system EPU parameters in the equivalency equation yields results greater than 1.0 because the parameters are also used to maintain suppression pool temperature below the design limits to meet inlet temperature analysis restrictions for the HPCI and RCIC pumps and to support increasing NPSH margin for the ECCS pumps.