PLA-6136, Proposed License Amendment, Arts/Mella Implementation Response to Request for Additional Information PLA-6136
| ML063420106 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 11/29/2006 |
| From: | Mckinney B Susquehanna |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PLA-6136 | |
| Download: ML063420106 (34) | |
Text
Brltt T. McKlnney PPL Susquehanna, LLC Sr. Vice President & Chief Nuclear Officer 769 Salem Boulevard PppI Berwick, PA 18603 Tel. 570.542.3149 Fax 570.542.1504 btmckinney@pplweb.com TM-NOV 2 9 2006 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop OPl-17 Washington, DC 20555-0001 SUSQUEHANNA STEAM ELECTRIC STATION PROPOSED LICENSE AMENDMENT NO. 279 FOR UNIT 1 OPERATING LICENSE NO. NPF-14 &
NO. 248 FOR UNIT 2 OPERATING LICENSE NO. NPF-22 ARTS/MELLLA IMPLEMENTATION RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Docket Nos. 50-387 PLA-6136 and 50-388
Reference:
"SusquehannaSteam ElectricStation ProposedLicense Amendment No. 279 for Unit I OperatingLicense No. NPF-14 and 248for Unit 2 OperatingLicense No. NPF-22ARTS/MELLLA implementation," dated November 18, 2005.
- 2) NRC Letter to Britt McKinney, "Requestfor Additional Information(RAI) -
SusquehannaSteam ElectricStation, Units I and 2 (SSES I and 2) -
Application to Implement Average Power Range Monitor/Rod Block Monitor!
Technical Specifications/MaximumExtended Load Line Analysis (ARTS/MELLLA)
(TAC Nos. MC9040 and MC9041)," dated October 19, 2006.
In accordance with 10 CFR 50.90, PPL Susquehanna, LLC (PPL) submitted a request for license amendment to the Susquehanna Steam Electric Station (SSES) Unit 1 and Unit 2 Technical Specifications to implement an expanded operating domain resulting from the implementation of Average Power Range Monitor/Rod Block Monitor/ Technical Specifications/Maximum Extended Load Line Limit Analysis (ARTS/MELLLA)
(Reference 1).
The purpose of this letter is to provide the PPL responses to the NRC RAI (Reference 2).
PPL has reviewed the 'No Significant Hazards Consideration' and the 'Environmental Consideration' submitted with Reference 1 relative to this supplemental information.
We have determined that there are no changes required to either of these documents.
A(),61
Document Control Desk PLA-6136 PPL respectfully requests that NRC expeditiously complete the review and approval of the proposed ARTS/MELLLA License Amendment Request, which was originally requested in Reference 1, to be completed by November 23, 2006. PPL continues to plan to implement ARTS/MELLLA for Unit 2 during the startup from the Spring 2007 Outage.
The PPL RAI responses contain information that AREVA NP Inc. considers proprietary.
AREVA NP Inc. requests that the proprietary information be withheld from public disclosure in accordance with 10CFR 2.390 (a) 4 and 9.17 (a) 4. An Affidavit supporting this request is provided in Attachment 3. A non-proprietary version of the PPL RAI responses is provided in Attachment 2.
If you have any questions or require additional information, please contact Mr. Mike Crowthers at (610) 774-7766.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on: Iq -Loo Attachments:
Attachment 1: Proprietary Version of the PPL RAI Responses Attachment 2: Non-Proprietary Version of the PPL RAI Responses Attachment 3: AREVA NP Inc. Affidavit cc: NRC Region I Mr. A. J. Blarney, NRC Sr. Resident Inspector Mr. R. V. Guzman, NRC Project Manager Mr. R. Janati, DEP/BRP
Attachment 2 to PLA-6136 Non-Proprietary Version of the PPL RAI Responses
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 1 of 27 NRC RAI l.a. L.b On Page 1-1 of Attachment 3 'in your submittal (Ref. 1) it states "The current licensed Extended Load Line Limit Analysis (ELLLA) power-flow region is replaced by the operating region bounded by the rod line which passes through the 100% of current licensed thermal power (CLTP) / 81.9% of Rated Core Flow (RCF) point, the rated thermal power (RTP) line, and the rated load line, which passes through 100% RCF."
- c. It is the staff s understanding that a rod line is not the same as an analytical line in that a rod line changes from cycle to cycle whereas an analytical line does not.
Explain the use of the term "rod line" in your above statement and provide a discussion on the difference between rod line and analytical line as you have used in the text above.
- d. Submit the specific equation used to determine the MELLLA domain for given power and flow conditions.
PPL Response to RAI L.a and RAI L.b The power/flow relationship that is characteristic of a BWR is a convenient method of defining an operating boundary. Depending on the licensed operating flexibility options at a plant (e.g., ICF, ELLLA, MELLLA), the operating boundaries will vary. As core flow is increased, power will increase as a function of core flow. This leads to the definition of various "rod lines", i.e., the MELLLA rod line, the rated rod line, etc.
The term "rated rod line" is typically defined as the rod line that intersects 100% rated power and 100% rated core flow. Other rod lines are defined as a multiple of this reference rod line by a constant multiplier at a given core flow.
In this submittal, the predefined "rod lines" are reference rod lines used analytically to defme the boundary conditions on the power/flow map. However, the actual rod line used during plant operation may vary over the course of a cycle, but must be maintained below the boundary conditions defined in the licensed power/flow map. Using the methodology approved by the NRC in Reference 1-1, GE established the following equation to define a rod line in terms of core power, P (percent rated), as a function of core flow, WT (percent rated):
P=(A+B.WT +c.w2).K Where:
P = Core Thermal Power (% of Rated)
A = 22.191 B = 0.89714
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 2 of 27 C = -0.0011905 WT = Core Flow (% of Rated)
K = Rod line multiplier Setting K = 1.0 produces the equation for the rated rod line that runs through the power/flow point defined by 100% rated power and 100% rated core flow. Rated core flow is defined as 100 Mlb/hr for SSES. The maximum core flow that SSES is licensed to operate under Increased Core Flow (ICF) conditions is 108 Mlb/hr or 108% rated core flow.
The MELLLA boundary is defined as the 120.8% rod line relative to Original Licensed Thermal Power (OLTP). The MELLLA boundary is fixed in terms of absolute thermal power. As a result, the MELLLA boundary is scaled by the ratio of OLTP/CLTP. For SSES, OLTP is 3293 MWt and CLTP is 3489 MWt. Therefore, the MELLLA boundary corresponds to the 114% rod line (120.8%/ox3293/3489) relative to CLTP. In the rod line equation, K = 1.14 is used to define the power/flow relationship along the MELLLA boundary relative to CLTP.
In summary, the term "rod line" is used analytically to define the power/flow boundary conditions for various licensed operating flexibility options. Actual rod lines are operational strategies that may vary over the cycle but must be maintained below the boundaries provided in the licensed power/flow map.
Reference 1-2. "Constant Pressure Power Uprate," NEDC-33004P-A, Revision 4, Class III, July 2003.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 3 of 27 NRC RAI 2 Submit an updated power/flow map that displays and clearly defines the following information:
- d. current ELLLA boundary lifie
- e. proposed MELLLA boundary line
- f. nominal flow-biased APRM rod block trip and scram setpoints for both current ELLLA and proposed MELLLA conditions PPL Response to RAI 2 The original ELLLA analysis for SSES defined the operating domain boundary below rated power as the APRM Rod Block line. The SSES Stretch Uprate submittal in Reference 2-1 as revised by References 2-2 and 2-3 increased power 4.5% above OLTP and power scaled the ELLLA boundary to the new rated thermal power of 3441 MWt.
Power scaling refers to scaling the boundary up in terms of absolute Megawatts such that the % power is the same value as a function of core flow that it was before the uprate.
The power scaling and use of the APRM Rod Block boundary continued in the SSES Appendix K Uprate submittal in Reference 2-4, which increased power to the CLTP value of 3489 MWt.
The line through points N and O in Figure 2-1 depicts a load line that extends along the APRM Rod Block line. The ELLLA boundary is the line labeled as ELLLA APRM Rod Block. The APRM Rod Block line restricts the operating domain more than the line that runs through points N and 0 since it includes the effect of drive flow that causes the downward curve of the line at low core flows. The MELLLA boundary is the line that runs through points A, B, C, and D in Figure 2-1.
Note that the reduced slope and uprated power scaling of the APRM Rod Block line causes the SSES ELLLA boundary to cross the MELLLA boundary at low core flows.
The APRM Rod Block slope was reduced for ELLLA to reduce restrictions at low power during startups. The ELLLA boundary intersects the 108% CLTP rod line at the APRM Rod Block clamped value. A power/flow map with the requested information is provided in Figure 2-1.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 4 of 27 References 2-5. PPL Letter PLA-3788, Susquehanna Steam Electric Station, Submittal of Licensing Topical Report on Power Uprate with Increased Core Flow, June 15, 1992.
2-6. PPL Letter PLA-3890, Susquehanna Steam Electric Station, Submittal of Revision 1 to Power Uprate Licensing Topical Report, December 18, 1992.
2-7. PPL Letter PLA-3900, Susquehanna Steam Electric Station, Correction to Power Uprate Licensing Topical Report Revision 1, January 8, 1993."
2-8. PPL Letter PLA-5212, Susquehanna Steam Electric Station, Proposed Amendment No. 235 to License NPF-14 and Proposed Amendment No. 200 to License NPF-22: Power Uprate, October 30, 2000.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 5 of 27 Figure 2 SSES MELLLA OperatingRange Power/FlowMap with APRM Rod Block and Scram Lines Core Flow (MIbthr) 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 4000 3500
- 3000 2500 0
200014 I-,
1500 1000 Soo 0
20 30 40 50 60 70 80 90 100 110 120 0 10 Core Flow (%)
The 100% Rod Une intersects maximum power at maximum core flow.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 6 of 27 NRC RAI 3 During single loop operation (SLO) what is the corresponding percent power and percent flow for MELLLA operation?
PPL Response to RAI 3 Currently, SLO is limited per procedure to power levels below the 80% rod line at core flows that are limited by the Technical Specification (LCO 3.4.1) recirculation pump speed limit of 80% under SLO. The 80% speed restriction effectively limits core flow to values less than 52 Mlb/hr.
Current SLO analyses support operation up to the SSES ELLLA boundary. Thus, operation under SLO conditions in the MELLLA region is also supported by current analyses, since the current ELLLA region is larger than the MELLLA region for SLO at SSES. This can be seen on the power/flow map supplied in the response to Question 2 which shows that at core flows less than the SLO 52 Mlb/hr limit, the ELLLA region bounds the MELLLA region. Therefore, single loop operation under MELLLA conditions is bounded by the current SSES ELLLA operating domain and analyses.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 7 of 27 NRC RAI 4 On Page 1-4 of Attachment 3 in your submittal it indicates that the APRM Flow-Biased Simulated Thermal Power (STP) Scram and APRM flow-biased rod block setpoints are clamped at 118% and 113.5%, respectively. State whether these values are percent of original licensed thermal power (OLTP) or of CLTP.
PPL Response to RAI 4 The APRM Flow-Biased STP Scram and Rod Block clamp analytical limits are 118%
and 113.5% of CLTP, respectively.
Non-Proprietary Version of the PPL RAI Responses> Attachment 2 to PLA-6136 Page 8 of 27 NRC RAI 5 Was a full-break spectrum analyzed for a loss-of-coolant accident (LOCA)? If so, please submit the results for the full-break spectrum analyses. Provide the limiting small-break and large-break peak cladding temperature. Was the LOCA analysis performed at SLO operating conditions? If so, please submit the results of this analysis.
PPL Response to RAI 5 A full break spectrum analysis was performed to identify the limiting LOCA break characteristics (location, type, size, single failure, axial power shape, and initial core flow). The maximum and minimum core flows allowed at rated core power in the MELLLA domain were analyzed in the break spectrum. The following limiting break characteristics were identified:
rLimiting ....
LOCA Break Characteristics Location Recirculation suction pipe (PS)
Type / size Double-ended guillotine
/ 0.6 discharge coefficient (0.6 DEG)
Single failure Low-pressure coolant injection (SF-LPCI)
Axial power shape Top-peaked (TOP)
Initial core flow 108 Mlb/hr (108F)
The Peak Clad Temperature (PCT) results for these limiting break conditions as well as the PCT for the minimum initial core flow were reported in Section 7.0 of the submittal as 1950 'F and 1945 *F, respectively. The maximum local oxidation is less than 2% and the core-wide metal-water reaction is less than 0.2%. The AREVA BWR LOCA methodology applies the same codes and methods for all break sizes and makes no distinction between small and large breaks. As identified above, the limiting break is a guillotine break, which has the largest possible break area.
A break in the active recirculation loop during SLO will result in an earlier loss of core heat transfer relative to a similar break occurring during two-loop operation. Therefore, break spectrum analyses were also performed to identify the limiting LOCA break characteristics for SLO operating conditions. The limiting break location and single failure were the same as identified for a LOCA initiated during two-loop operation.
However, the limiting break type and size were identified to be a split break with an area of 3.5 ft2 and the limiting axial power shape was identified to be mid-peaked. The increased severity of an SLO LOCA is reduced by applying an SLO multiplier to the two-loop MAPLHGR limits. The SLO multiplier was established so that the limiting PCT for SLO was less than the limiting PCT for two-loop operation.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 9 of 27 NRC RAI 6 Provide additional discussion on what kind of axial power profiles were assumed in the large-break LOCA analysis.
PPL Response to RAI 6 Axial power profiles vary between bottom-peaked, mid-peaked, and top-peaked during normal operation of a reactor cycle. Mid-peaked and top-peaked axial power profiles are potentially limiting for LOCA and are analyzed as part of the break spectrum.
Mid-peaked axial power profiles are potentially limiting because the highest powered plane is equidistant from coolant sources of ECCS sprays above the core and core reflood from below due to ECCS coolant accumulation. Top-peaked axial power profiles are potentially limiting because the highest powered plane could experience Critical Heat Flux (CHF) sooner, and it will take longer to reflood. Bottom-peaked axial power profiles are not limiting because the highest powered plane will experience CHF later and it will reflood sooner.
The break spectrum calculations, which included support for two-loop and single-loop operation, analyzed the four axial power profiles shown in the following figures:
1]
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 10 of 27 1[
1]
Non-Proprietary Version of the PPL'RAI Responses' Attachment 2 to PLA-6136 Page 11 of 27 NRC RAI 7 Section 3.0 of Attachment.3 in your submittal states the transient analyses performed are based on SSES-2 Cycle 13. Discuss the similarities and differences between SSES-1 and SSES-2 in terms of transient response, geometry, system performance, and core design.
PPL Response to RAI 7 The SSES units are analyzed using a single model to represent both units. Based on satisfactory results obtained from SSES transient model development and benchmarking (References 7-1 and 7-2), it was determined that the SSES units were similar enough to not warrant separate modeling of the reactors. Therefore, from a geometry standpoint, the units are treated as being the same.
The SSES units have the same number of major components with similar performance characteristics. Each unit has the following major components: three feedwater heater strings, three turbine driven feedwater pumps, two reactor recirculation pumps, one reactor core isolation cooling pump, sixteen safety relief valves, and two main steam isolation valves per each of the four main steam lines. Each unit also has the same number and type of pumps in the ECCS including one HPCI pump, four core spray pumps, and four residual heat removal pumps. Therefore, the system performance of both units is similar.
Transient response is governed by system geometry, system performance, and core design. Currently, both SSES cores consist of full cores of ATRIUM-10 fuel with scatter loading. Unit capacity factor which is directly related to the unit's operating history (maintenance outages, unplanned shutdown, scrams, etc.) has one of the largest impacts on core designs. If a given unit operates better or worse with respect to the other, the core design for that unit must be altered to compensate for this impact.
Each unit has a core design that is tailored to compensate for its individual operating history. Due to the uniqueness of each unit's core deign, the transient analysis for each unit is performed specific to that unit's core design.
In summary, a single model is used to represent the geometry and predict system performance for both SSES units. Transient response is unique for each unit since the specific core for each unit is explicitly modeled.
References 7-1. PL-NF-89-005-A, Qualification of Transient Analysis Methods for BWR Design and Analysis, July 1992.
7-2. PL-NF-90-001-A, Application of Reactor Analysis Methods for BWR Design and Analysis, July 1992.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 12 of 27 NRC RAI 8.a, 8.b. 8.c Section 3.1 of Attachmeiit 3Si your submittal lists seven"different anticipated operational occurrence (AOO) events that are considered potentially limiting in the ARTS/MELLLA region and were reviewed as part of the ARTS program development. These events are:
(1) Generator Load Reject with No Bypass (LRNBP), (2) Turbine Trip with No Bypass (TTNBP), (3) Feedwater Controller Failure Maximum Demand, (4) Loss of Feedwater Heating (LFWH), (5) Fuel Loading Error, (6) Inadvertent High Pressure Coolant Injection Startup, and (7) Recirculation Flow Increase.
- d. In order for the NRC staff to reach its conclusion for the proposed changes submitted in your submittal, it is necessary to review the results for each of the events considered to be potentially limiting in the ARTS/MELLLA region.
Analyze each of the seven AOO events above assuming the proposed power/flow conditions and submit the results.
- e. The applicant states the LRNBP and TTNBP events were conservatively combined as one event. Explain how combining the two events into one is more conservative than the two individual events. Discuss how the combined LRNBP/TTNBP event adequately demonstrates core response while operating in the MELLLA region. State the uncertainties, assumptions, and system actuations assumed in the combined LRNBP/'ITNBP to make this event more conservative than the individual LRNBP and TTNBP events. Explain if this approach is part of the NRC-approved Framatome licensing methodology.
- f. The amendment request states the LFWH evaluation for SSES-2 Cycle 13 considered the flow range for the MELLLA region and that the results showed the LFWH event is not limiting for SSES 1 and 2. The document also states the effect of MELLLA on the LFWH severity is sufficiently small and the LFWH remains not limiting for MELLLA. Since the LFWH event is a slow event and higher core flow could potentially have adverse limiting affects, perform an LFWH analysis using increased core flow (ICF) and provide the results.
PPL Response to RAI 8.a The results provided in Section 3 of the submittal are based on calculations that were explicitly performed for the MELLLA domain. Therefore, as discussed below, the results presented in the submittal can be used to draw conclusions about the potentially limiting events in the ARTS/MELLLA region.
Non-Proprietary Version of the PPL RAI Responses" Attachment 2 to PLA-6136 Page 13 of 27 The MCPR operating limit results for the most limiting events (LRNBP/TTNBP and FWCF) at the minimum and maximum core flow conditions allowed at rated core power are provided in Table 3-3Y6f the submittal. The change in CPR, which is used to establish the MCPR operating limit, and the change in LHGR, which is used to establish the LHGRFAC multiplier, are from the case which provided the most severe result.
The LFWH event produces a maximum MCPR operating limit of 1.27 for the flow range of 81 to 108 Mlbm/hr. at rated power. This limit is compared to the limiting transient (LRNBP/TTNBP) operating limit of 1.36 in the bulleted paragraph on the bottom of page 3-1 of the submittal. The LFWH is not the limiting event for the change in CPR or the change in LHGR. The LFWH event remains nonlimiting under MELLLA conditions.
The fuel loading error is a highly localized core event which is dependent on the core loading pattern. The use of MELLLA will not introduce significant changes to the core loading pattern. Therefore, the fuel loading error continues to be nonlimiting for the reduced core flow which is available with the MELLLA domain.
The Inadvertent HPCI Startup event produces a maximum MCPR operating limit value of 1.26 for the flow range of 81 to 108 Mlbm/hr. at rated power. This limit is compared to the limiting transient (LRNBP/TTNBP) operating limit of 1.36 in the second bulleted paragraph on page 3-2 of the submittal. It is concluded based on this comparison that the HPCI event remains nonlimiting under MELLLA conditions. LHGRFAC multipliers are established to protect the HPCI event.
The recirculation flow increase event is protected by the flow dependent MCPR limits and LHGRFAC multipliers established to protect the slow flow excursion. The limits and multipliers shown in Figures 3-3 and 3-4 of the submittal were established to protect this event initiated from anywhere within the MELLLA domain.
PPL Response to RAI 8.b The LRNBP and TTNBP events are combined by modeling the simultaneous closure of the turbine control and stop valves. In a load rejection at the Susquehanna units, stop valve closure would occur shortly after control valve closure and vice versa for a turbine trip. Not modeling the short delay between closures of the stop and control valves is slightly conservative because it results in a conservative valve area versus time profile.
However, the amount of conservatism is small since the valve closures are so rapid.
When the short delay is neglected (i.e., assuming the simultaneous closure of the turbine control and stop valves), it makes no difference which valve begins to close first and LRNBP and TTNBP are equivalent.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 14 of 27 The combination of the TTNBP and LRNBP events does not create a different type of event than that for which the licensing methodology was approved. The conservative combination of two similar pressurization events with rapid valve closure still results in a pressurization event which can be adequately analyzed with the approved licensing methodology. This means that the approved methodology remains applicable to either analysis approach.
The conservative superposition of the valve closure profiles does not significantly increase the severity of the combined event relative to the separate events. This being the case, the analyses can be performed in combination or separately without adversely affecting the operating limits that are produced from the event.
PPL Response to RAI 8.c The Maximum Extended Operating Domain (MEOD), which is the Combination of MELLLA and Increased Core Flow (ICF), was considered for the analyses presented in the submittal. The LFWH analysis considered the entire MELLLA flow range including ICF at rated power. The maximum MCPR operating limit for the LFWH transient for these conditions is 1.27 based on the reload analysis results. The maximum MCPR operating limit of 1.27 occurs at the ICF core flow value of 108 Mlb/hr at rated power.
The LFWH results are slightly less severe at reduced core flows at rated power.
Therefore, the effect of MELLLA on the LFWH severity is sufficiently small and actually provides less severe results.
The most limiting event at rated power over the MELLLA flow range, including ICF, is the LRNBPFTTNBP event which produces a maximum MCPR operating limit of 1.36.
This shows that there is substantial margin between the events and substantiates the conclusion that the LFWH event remains nonlimiting for SSES under MELLLA conditions.
For all LFWH cases (nominal and ICF), the final LHGR remained well below the Protection Against Power Transient (PAPT) limit.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 15 of 27 NRC RAI 9.a. 9.b. 9.c On Page 1-4 of Attachment 3 in Reference 1 it states "The APRM Flow-Biased Simulated Thermal Power scram line is conservatively not credited in any SSES licensing analyses. In addition, the APRM Flow-Biased STP rod block line is conservatively not credited in any SSES 1 and 2 safety licensing analyses, although it is part of the SSES design configuration."
- a. Does this mean that for any transient/accident initiated at less than rated conditions that only the fixed scram of 113.5% is assumed? Provide a table that lists exactly which analyses assumed a scram at the fixed scram setpoint of 113.5% and which analyses did not.
- b. State the Framatome thermal and mechanical overpower limits. Provide technical justification explaining why a scram at the fixed value of 113.5% would not result in exceeding thermal overpower limits for off-rated conditions (conditions under the MELLLA domain or conditions other than normal steady-state conditions).
- c. Provide the thermal and mechanical overpower limits calculated for transients initiated from the rated conditions and along the MELLLA operating domain.
PPL Response to RAI 9.a The codes used to perform transient analyses model several potential scram signals.
However, the flow-biased simulated thermal power scram is not modeled in any transient analyses performed by AREVA (formerly Framatome). AREVA transient analyses do model the fixed high neutron flux scram which has an analytical limit value of 122%.
Most transients that experience a scram receive the signal to scram before reaching a flux of 122%. The scram for potentially limiting transients is initiated by turbine control valve fast closure (LRNB), turbine stop valve position (TTNB, FWCF), high dome pressure (LRNB, TTNB and FWCF initiated for P < Pbypass), or MSIV position (LOCA). The scram was initiated by high flux for the results presented in Section 5, Vessel Overpressure Protection. The high flux scram could be the first scram signal received during a rapid Recirculation Flow Increase (RFI) event initiated from a high rod line, but this event is less severe than a slower RFI which does not reach the high flux scram.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 16 of 27 PPL Response to RAI 9.b AREVA applies NRC-approved methodology to establish steady state (Fuel Design Limit - FDL) and transient (Protection Against Power Transient - PAPT) LHGR limits.
The FDL and PAPT ensure that the SAFDLs of no fuel centerline melt and <1% cladding strain (( )) are not exceeded (Reference 9-1). The FDL and PAPT limits for Susquehanna ATRIUM-10 fuel are shown in the attached Figure 9-1.
Plants without MEOD or ARTS use FDLRC and APRM scram set downs to ensure the SAFDLs are not exceeded. For plants with MEOD or ARTS, protection of the SAFDLs is accomplished by providing multipliers (5 1) on the steady state LHGR limit which are a function of core power and core flow (LHGRFACp and LHGRFACf). The LHGRFAC multipliers applicable for the MELLLA domain are presented in Figures 3-2 and 3-4 of the submittal. The transient analyses performed in support of these multipliers did not credit the flow-biased simulated thermal power scram. These multipliers ensure that fuel assemblies are monitored with an LHGR limit that provides sufficient margin to protect acceptance criteria for events which are more severe when initiated from off-rated conditions.
PPL Response to RAI 9.c The steady state LHGR limit presented in the attached Figure 9-1 and the LHGRFAC multipliers presented in Figures 3-2 and 3-4 of the submittal ensure that fuel assemblies are monitored with an LHGR limit that provides sufficient margin to protect acceptance criteria for events initiated from the rated conditions and along the MELLLA operating domain.
Reference Figure 13-2 EMF-85-74(P) Revision 0, Supplement I(P) (A) and Supplement 2(P) (A),
RODEX 2A (BWR) Fuel Rod Thermal-Mechanical Evaluation Model, Siemens Power Corporation, February 1998.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 17 of 27 20 19 18 17 16 15 14 13 2-12 3:11
ý-11 0 S9
-8 7
6 5
4 3
2 1
0 0 10 20 30 40 50 60 70 Planor Exposure (GWd/MTU)
Figure9-1 ATRIUM-]O LHGR Limitsfor Normal OperationandAOO
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 18 of 27 NRC RAI 10 Provide the safety relief valve (SRV) setpoints assumed in your LOCA, vessel overpressure, and Anticipated Transient Without Scram analyses. Demonstrate the continued adequacy of the current SRV setpoints with respect to your recent as-found valve test performance values. Explain why the current SRV setpoints are still applicable for the proposed MELLLA operating domain.
PPL Response to RAI 10 The ATWS analysis is performed using the Technical Specification SRV safety setpoints.
The LOCA and vessel overpressure analyses are performed using the Technical Specification SRV safety setpoints and a 3% tolerance.
The Technical Specification safety relief valve settings per surveillance requirement 3.4.3.1 are:
Setpoint Number of Valves 1175 psig 2 1195 psig 6 1205 psig 8 Actual historical in-service surveillance test results of SRV performance are monitored for compliance to the Technical Specification requirements. To-date, of 261 "as found" SRV lift setpoint verification tests performed from 1985 to 2005, only 2 SRV tests were found to exceed the current +3% setpoint tolerance, and 13 tests were found to lift below the -3% setpoint tolerance. Thus, the in-service surveillance testing of the plant's SRVs has not shown a significant propensity for high setpoint drift greater than 3%.
The performance of the SRVs are unaffected by operation in the MELLLA domain.
The results presented in the submittal show that applicable analysis requirements continue to be met under MELLLA conditions. Therefore, the current SRV setpoints remain valid.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 19 of 27 NRC RAI 11 Page 6-2 of Attachment 3 in your submittal states, "PPL has committed to review the applicability of the ICA [interim corrective action] regions on a cycle-specific basis, and take appropriate action to revise the ICA regions if needed." State what the cycle-specific ICA region changes and Option III boundary changes are for MELLLA. State whether the applicability of the ICA and the Option III boundaries were confirmed and provide the updated instability power/flow boundaries.
PPL Response to RAI 11 The stability region boundaries are re-evaluated each cycle using results from the cycle specific stability evaluation that is dependent upon the projected operating conditions from the cycle step-out. The MELLLA operating domain allows lower core flow rates to be used at rated power, relative to the current operating domain, early in the cycle when CPR is not limiting. The use of lower core flow rates early in the cycle will increase the depletion rate of the fuel in the bottom of the core and lead to a higher boiling boundary near the end of the cycle when stability is generally limiting. Operating with the lower core flow rates allowed by the MELLLA operating domain will tend to stabilize the core.
The cycle step-out used for the Unit 2 Cycle 13 stability region determination uses a core flow range that maintains margin (i.e., higher flows) to the minimum core flow allowed by MELLLA. The results determined for Unit 2 Cycle 13 will be similar to MELLLA operation. The stability boundaries determined from the Unit 2 Cycle 13 analysis are provided in the accompanying power/flow map.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 20 of 27 Figure 11 SSES MELLLA Operating Range Power/Flow Map with Stability Regions Core Flow (Mlb/hr) 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 I
1 Z
A I.
0 10 20 30 40 50 60 70 80 90 100 110 120 The 100% Rod Line intersects maximum power at maximum core flow. Core Flow (%)
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 21 of 27 NRC RAI 12 In the GENE [computer code] methodology, the ARTS off-rated limits were developed from series of sensitivity analyses that are subsequently confirmed in new applications.
State if the off-rated limits will be performed on cycle-specific bases for the Framatome methodology.
PPL Response to RAI 12 The off-rated limits are currently calculated on a cycle specific basis, and it is currently planned to continue to calculate the off-rated limits on a cycle specific basis using approved Framatome methodology.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 22 of 27 NRC RAI 13 Provide the NRC-approved reference document that describes the Framatome off-rated thermal limit methodology (i.e., minimum critical power ratio (MCPRp, MCPRf), linear heat generation rate (LHGR, LHGRFACp)).
PPL Response to RAI 13 When establishing thermal limits, AREVA applies the same NRC-approved methodologies for rated and off-rated operation. AREVA uses NRC-approved codes and models to establish limits which are used to monitor fuel assemblies to ensure that NRC-approved criteria are protected.
References 13-1 through 13-5, which are listed in the SSES Technical Specifications, are the NRC-approved documents AREVA applies to establish MCPR limits. MCPR limits are established as a function of core power (MCPRp) and core flow (MCPRf) to protect the acceptance criteria for events which are more severe when initiated from off-rated conditions.
References 13-6 through 13-9, which are listed in the SSES Technical Specifications, are the NRC-approved documents AREVA applies to establish LHGR limits. Steady state and transient LHGR limits are established to ensure that acceptance criteria are not exceeded. Plants without MEOD or ARTS use FDLRC and APRM scram set downs to ensure that all acceptance criteria are protected. For plants with MEOD or ARTS, protection is accomplished by providing multipliers (< 1) on the steady state LHGR limit which are a function of core power and core flow (LHGRFACp and LHGRFACf). The multipliers ensure that fuel assemblies are monitored with an LHGR limit that provides sufficient margin to protect acceptance criteria for events which are more severe when initiated from off-rated conditions.
References 13-1. ANF-524(P)(A) Revision 2 and Supplements 1 and 2, ANF Critical Power Methodology for Boiling Water Reactors, Advanced Nuclear Fuels Corporation, November 1990.
13-2. XN-NF-84-105(P)(A) Volume 1 and Volume 1 Supplements 1 and 2, XCOBRA-T: A Computer Code for BWR Transient Thermal-Hydraulic Core Analysis, Exxon Nuclear Company, February 1987.
13-3. ANF-913(P)(A) Volume 1 Revision 1 and Volume 1 Supplements 2, 3 and 4, COTRANSA2: A Computer Program for Boiling Water Reactor Transient Analysis, Advanced Nuclear Fuels Corporation, August 1990.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 23 of 27 13-4. EMF-2158(P)(A) Revision 0, Siemens Power Corporation Methodology for Boiling Water Reactors: Evaluation and Validation of CASMO-4/
MICROBURN-B2, Siemens Power Corporation, October 1999.
13-6. EMF-2209(P)(A) Revision 2, SPCB Critical Power Correlation, Framatome ANP, September 2003.
13-6. XN-NF-81-58(P)(A) Revision 2 and Supplements 1 and 2, RODEX2 Fuel Rod Thermal-Mechanical Response Evaluation Model, Exxon Nuclear Company, March 1984.
13-7. XN-NF-85-67(P)(A) Revision 1, Generic Mechanical Design for Exxon Nuclear Jet Pump BWR Reload Fuel, Exxon Nuclear Company, September 1986.
13-8. EMF-85-74(P) Revision 0 Supplement 1(P)(A) and Supplement 2(P)(A),
RODEX2A (BWR) Fuel Rod Thermal-Mechanical Evaluation-Model, Siemens Power Corporation, February 1998.
13-9. ANF-89-98(P)(A) Revision 1 and Supplement 1, Generic Mechanical Design Criteria for BWR Fuel Designs, Advanced Nuclear Fuels, May 1995.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 24 of 27 NRC RAI 14 Table 1-1 of Attachment 3 in Reference 1 states that the ISCOR computer code is used to calculate the reactor heat balance. Please explain the applicability of the use of this General Electric code for Framatome analysis or reference the appropriate Frarnatome reactor heat balance computer code used.
PPL Response to RAI 14 The General Electric code ISCOR was not used for Framatome analysis. Framatome also has a computer code used to calculate the reactor heat balance. This reactor heat balance is included as a subroutine (HTBAL) within MICROBURN-B2 (Reference 14-1). This same reactor heat balance can also be executed as a stand alone code (HTBAL).
Reference 14-1. EMF-2158(P)(A) Revision 0, Siemens Power Corporation Methodology for Boiling Water Reactors: Evaluation and Validation of CASMO-4/MICROBURN-B2, Siemens Power Corporation, October 1999.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 25 of 27 NRC RAI 15 In the Framatome safety limit MCPR (SLMCPR) methodology, state whether the SLMCPR is calculated at the minimum core flow statepoint at the current RTP? Justify how it is ensured that the control rod patterns assumed in the SLMCPR calculation at the minimum and RCF statepoints will bound the control rod patterns employed at the plant.
Discuss how operating flexibility in terms of planned and actual control rod patterns at the plant is achieved while ensuring that the power distribution assumed in the analyses remain limiting.
PPL Response to RAI 15 AREVA SLMCPR analyses are performed at the minimum and maximum core flow allowed at rated power. ((
0 Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 26 of 27 Reference 15-1. ANF-524(P)(A) Revision 2 and Supplements 1 and 2, ANF Critical Power Methodology for Boiling Water Reactors, Advanced Nuclear Fuels Corporation, November 1990.
Non-Proprietary Version of the PPL RAI Responses Attachment 2 to PLA-6136 Page 27 of 27 NRC RAI 16 Reference the specific SLMCPR sections in the NRC-approved licensing topical report that discuss how the limiting control rod patterns are selected.
PPL Response to RAI 16 Reference 16-1 is the NRC-approved licensing topical report which describes the AREVA methodology for SLMCPR. Section 5 addresses how AREVA performs SLMCPR analyses. Supplement 1 addresses how fuel channel bow is accounted for in AREVA SLMCPR analyses, and Supplement 2 contains NRC correspondence associated with the review of the AREVA SLMCPR methodology.
Reference 16-1. ANF-524(P)(A) Revision 2 and Supplements 1 and 2, ANF Critical Power Methodology for Boiling Water Reactors, Advanced Nuclear Fuels Corporation, November 1990.
to PLA-6136 AREVA NP Inc. Affidavit
AFFIDAVIT STATE OF WASHINGTON )
) ss.
COUNTY OF BENTON )
- 1. My name is Jerald S. Holm. I am Manager, Product Licensing, for AREVA NP Inc. and as such I am authorized to execute this Affidavit.
- 2. I am familiar with the criteria applied by AREVA NP to determine whether certain AREVA NP information is proprietary. I am familiar with the policies established by AREVA NP to ensure the proper application of these criteria.
- 3. I am familiar with the AREVA NP information contained in the PPL letter PLA-6136 with the subject PPL RAI Responses and referred to herein as *Document.' Information contained in this Document has been classified by AREVA NP as proprietary in accordance with the policies established by AREVA NP for the control and protection of proprietary and confidential information.
- 4. This Document contains information of a proprietary and confidential nature and is of the type customarily held in confidence by AREVA NP and not made available to the public. Based on my experience, I am aware that other companies regard information of the kind contained in this Document as proprietary and confidential.
- 5. This Document has been made available to the U.S. Nuclear Regulatory Commission in confidence with the request that the information contained in this Document be withheld from public disclosure. The request for withholding of proprietary information is made in accordance with 10 CFR 2.390. The information for which withholding from disclosure is
requested qualifies under 10 CFR 2.390(a)(4) 'Trade secrets and commercial or financial information*.
- 6. The following criteria are customarily applied by AREVA NP to determine whether information should be classified as proprietary:
(a) The information reveals details of AREVA NP's research and development plans and programs or their results.
(b) Use of the information by a competitor would permit the competitor to significantly reduce its expenditures, in time or resources, to design, produce, or market a similar product or service.
(c) The information includes test data or analytical techniques concerning a process, methodology, or component, the application of which results in a competitive advantage for AREVA NP.
(d) The Information reveals certain distinguishing aspects of a process, methodology, or component, the exclusive use of which provides a competitive advantage for AREVA NP in product optimization or marketability.
(e) The information is vital to a competitive advantage held by AREVA NP, would be helpful to competitors to AREVA NP, and would likely cause substantial harm to the competitive position of AREVA NP.
The information in the Document is considered proprietary for the reasons set forth in paragraphs 6(b) and 6(c) above.
- 7. In accordance with AREVA NP's policies governing the protection and control of information, proprietary information contained in this Document have been made available, on a limited basis, to others outside AREVA NP only as required and under suitable agreement providing for nondisclosure and limited use of the information.
- 8. AREVA NP policy requires that proprietary information be kept in a secured file or area and distributed on a need-to-know basis.
- 9. The foregoing statements are true and correct to the best of my knowledge, information, and belief.
SUBSCRIBED before me this C 2 -
day of nJ 2006. 4 &
E rNOTARy SO Leslie M. Koep IA t
NOTARY PUBLIC, STATE OF WASHINGTON MY COMMISSION EXPIRES: 6118/2007