ML17195A285
| ML17195A285 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 07/13/2017 |
| From: | David Helker Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TAC MF9289, TAC MF9290 | |
| Download: ML17195A285 (17) | |
Text
Exelon Generation@
200 Exelon Way Kennett Square, PA 19348 www.exeloncorp.com July 13, 2017 10 CFR 50.90 10 CFR 50, Appendix K U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Peach Bottom Atomic Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-46 NRC Docket Nos. 50-277 and 50-278 Measurement Uncertainty Recapture License Amendment Request -
Supplement 2 Response to Request for Additional Information
References:
- 1.
Exelon letter to the NRC, "Request for License Amendment Regarding Measurement Uncertainty Recapture Power Uprate,"
dated February 17, 2017 (ADAMS Accession No. ML17048A444)
Email from R. Ennis (USNRC) to D. Neff (Exelon), "Peach Bottom Atomic Power Station, Units 2 and 3 - Request for Additional Information Regarding License Amendment Request for Measurement Uncertainty Recapture Power Uprate (TAC Nos.
MF9289 and MF9290)," dated June 26, 2017 (ADAMS Accession No. ML17177A248)
- 2.
In accordance with 10 CFR 50.90, Exelon Generation Company, LLC (Exelon) requested amendments to Renewed 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 Facility Operating Licenses to implement an increase in rated thermal power from 3951 megawatts thermal (MWt) to 4016 MWt. During their technical review of the application, the NRC Staff identified the need for additional information.
Reference 2 provided the Requests for Additional Information (RAls) from four NRC review branches. The Attachment to this letter provides the responses to the RAls from each of those branches.
Exelon 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.
MUR LAR Supplement 2 Response to Request for Additional Information July 13, 2017 Page 2 In accordance with 10 CFR 50.91, "Notice for public comment; State consultation,"
paragraph (b}, Exelon is notifying the Commonwealth of Pennsylvania and the State of Maryland of this response by transmitting a copy of this letter 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 (610) 765-5631.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 13th day of July 2017.
Respectfully, David P. Helker Manager - Licensing & Regulatory Affairs Exelon Generation Company, LLC
Attachment:
Responses to Requests for Information from NRC Review Branches APHB, EICB, SBPB and EEOB cc:
USNRC Region I, Regional Administrator USNRC Senior Resident Inspector, PBAPS USNRC Project Manager, PBAPS R. R. Janati, Pennsylvania Bureau of Radiation Protection S. T. Gray, State of Maryland
Attachment Peach Bottom Atomic Power Station, Units 2 and 3 NRC Docket Nos. 50-277 and 50-278 Response to Requests for Additional Information from NRC Review Branches APHB. EICB. SBPB and EEOB
MUR LAR Supplement 2 Responses to Requests for Information Responses to NRC Staff's Request for Additional Information Attachment Page 1of14 By application dated February 17, 2017, as supplemented by letter dated March 20, 2017 (Agencywide Documents Access and Management System (ADAMS) Accession Nos.
ML17048A444 and ML17080A067, respectively), Exelon Generation Company, LLC (Exelon, the licensee) submitted a license amendment request (LAR) for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3. The amendments would revise the Renewed Facility Operating Licenses and Technical Specifications (TSs) to implement a measurement uncertainty recapture (MUR) power uprate. Specifically, the amendments would authorize an increase in the maximum licensed thermal power level from 3,951 megawatts thermal (MWt) to 4,016 MWt which is an increase of approximately 1.66%.
In an email dated June 26, 2017, from the NRC (Rick Ennis) to Exelon (David Neff) (ADAMS Accession No. ML17177A248), the NRC provided Requests for Additional Information (RAls) seeking clarification of certain issues related to those RAls. Exelon agreed to provide a response to the RAls by July 26, 2017.
APHB-RAl-1 to the licensee's application dated February 17, 2017, provides a cross-reference to the topic areas discussed in Attachment 1 to NRC Regulatory Issue Summary (RIS) 2002-003, "Guidance on the Content of Measurement Uncertainty Recapture Power Uprate Applications," (ADAMS Accession No. ML013530183). Items Vll.1 through Vll.4 in Attachment 1 to RIS 2002-003 pertain to the operator training and human factors review. to the licensee's application, GE - Hitachi Nuclear Energy (GEH), "Safety Analysis Report for Peach Bottom Atomic Power Station, Units 2, and 3, Thermal Power Optimization,"
NEDC-33873P, Revision 0, dated February 2017, summarizes the evaluations performed for PBAPS for the proposed MUR. This proprietary report is referred to as the TSAR (i.e., Thermal Power Optimization Safety Analysis Report). A public version of the TSAR, GEH report NED0-33873, is contained in Attachment 7 to Exelon's application.
The cross-reference in Attachment 4 to the licensee's application lists Section 10.9 of the TSAR as responsive to the issues addressed by Item Vll.2A in Attachment 1 to RIS 2002-003 regarding emergency and abnormal operating procedures (AOPs). However, no specific information regarding AOPs was provided in Section 10.9 of the TSAR or any other part of the application.
Please provide information related [to] any changes to the PBAPS AOPs or provide a statement confirming that there are no impacts to the AOPs per the guidance in Attachment 1 to RIS 2002-003, Item Vll.2A.
RESPONSE
The MUR uprate will have no effect on the AOP strategies and will have only minor changes to setpoints and thresholds contained in the procedures. The AOP updates will be addressed using the standard Exelon procedure updating processes. There are no changes to AOPs that would adversely affect defense in depth or safety margins.
MUR LAR Supplement 2 Responses to Requests for Information APHB-RAl-2 Attachment Page 2of14 The cross-reference in Attachment 4 to the licensee's application lists Section 10.5 of the TSAR and Section 3.5.6 of Attachment 1 to the application as responsive to the issues addressed for Item Vll.2C in Attachment 1 to RIS 2002-003. This item relates to the identification of all modifications, associated with the control room plant reference simulator, to ensure that changes in operator actions do not adversely affect defense in depth or safety margins.
However, Section 3.5.6 of Attachment 1 only states that the PBAPS simulator will be modified to reflect any changes to the control room in accordance with established PBAPS certification procedures. No specific modifications associated with the PBAPS simulator are identified, nor is any justification provided assuring that defense in depth or safety margins will not be adversely affected. Section 10.5 of the TSAR does not reference the PBAPS control room simulator at all.
Please identify any modifications associated with the PBAPS simulator and provide the information needed to justify that any changes in operator actions do not adversely affect defense in depth or safety margins per the guidance in RIS 2002-003, Attachment 1, Item Vll.2C.
RESPONSE
Modifications to the plant simulator are limited to model changes to reflect the conditions at the higher thermal power level; setpoint changes that are necessary for operation at thermal power optimization (TPO) conditions; plant computer changes such as Plant Monitoring System (PMS) alarm points and the Safety Parameter Display System (SPDS) display; and minor instrumentation changes to provide adequate indicating range. There are no changes to the plant simulator that would adversely affect defense in depth or safety margins.
EICB-RAl-1 In the previous MUR power uprate for PBAPS (ADAMS Accession No. ML031000317}, a calorimetric core thermal power measurement uncertainty of +/-0.38% of rated thermal power (RTP} was used to support a power level increase of 56 MWt (1.62% of RTP). In the current amendment request, a measurement uncertainty of +/-0.34% is being used to support the requested power level increase of 65 MWt (1.66% of RTP).
Since the license amendment request states that the previously installed leading edge flow meter (LEFM) instruments are to be credited for the current amendment request and that "[n]o modifications to the LEFM are needed for the thermal power optimization (TPO) implementation," the NRC staff needs to understand the factors that are attributable to this new smaller uncertainty value. Please provide additional information on previous and current uncertainty factors to establish a basis for the new reduced uncertainties of the installed LEFM instruments. This information is needed to satisfy the criteria of RIS 2002-003, Attachment 1, Item 1.1.E, which states that feedwater flow measurement technique and power measurement uncertainty should include a detailed description that includes a calculation of the total power measurement uncertainty at the plant, explicitly identifying all parameters and their individual contribution to the power uncertainty.
MUR LAR Supplement 2 Responses to Requests for Information
RESPONSE
Attachment Page 3of14 The reduction in core thermal power (CTP) measurement uncertainty is not due to a change in the LEFM uncertainty related to this MUR uprate.
A significant portion (0.02%) of this apparent 0.04% (0.38% - 0.34%) reduction in CTP measurement uncertainty is due to a difference in terminology. The +/-0.38% uncertainty cited in the RAI is the credited uncertainty for the 2002 MUR uprate whereas the +/-0.34% cited for this MUR LAR is the analyzed uncertainty. For both submittals, an analytical CTP measurement uncertainty value was calculated, with a corresponding allowable RTP level. That RTP level was rounded down to the nearest whole megawatt, which effectively produced a slightly higher credited CTP measurement uncertainty. In 2002, the analyzed CTP measurement uncertainty was +/-0.36% and the credited uncertainty was +/-0.38%. In the current submittal, the analyzed CTP measurement uncertainty is +/-0.34% which corresponds to a power level of 4016.6 MWt.
This was then rounded down to the nearest whole megawatt of 4016 MWt, which corresponds to the credited uncertainty of +/-0.355%. Therefore, comparing like terms, the actual difference in credited uncertainties between the 2002 MUR and this request is 0.025% (0.38% - 0.355%).
The actual difference in analyzed uncertainties between the 2002 MUR and this request is 0.02% (0.36% - 0.34%).
The largest contributor to the 0.02% reduction in analyzed CTP measurement uncertainty arises from a difference in the application of a steam table enthalpy correlation uncertainty term. In 2002, this uncertainty term was applied to the overall CTP measurement uncertainty, which incorrectly included terms unrelated to enthalpy values. In the current MUR analysis, this uncertainty term was appropriately applied to only the individual enthalpy based terms. A secondary contributor to the reduction in analyzed CTP measurement uncertainty is associated with crediting the use of more accurate Measurement and Test Equipment when calibrating certain plant instruments.
EICB-RAl-2 TSAR Section 10.8 states that minor changes are required to restore the TPO requirements to ensure that plant procedures and programs are in place to control the software and hardware configuration of the associated instrumentation.
The NRC staff needs to understand what measures are being taken by the licensee to maintain control over software in instruments that affect the power calorimetric (i.e., LEFM software, Process Plant Computer Software). Please provide a description of the software control measures used for calorimetric instruments at PBAPS including a discussion of the changes being made to restore the TPO requirements as described in the TSAR. This information is needed to satisfy the criteria of RIS 2002-003, Attachment 1, Item 1.1.F.ii, "controlling software and hardware configuration."
RESPONSE
LEFM and Plant Process Computer (PPC) application software, already classified per Exelon's Digital Technology Software Quality Assurance (DTSQA) program, is not being modified for MUR. Certain configurable settings within the LEFM software will be updated, PPC computer displays will be modified, and computer points will be rescaled. All of these changes will be
MUR LAR Supplement 2 Responses to Requests for Information Attachment Page 4of14 controlled under existing configuration control processes, including Exelon procedures CC-AA-103, "Configuration Control for Permanent Physical Plant Changes" and CC-AA-256, "Process for Managing Plant Modifications Involving Digital Instrumentation & Control Equipment and Systems."
SBPB-RAl-1 The Updated Final Safety Analysis Report (UFSAR) and the application state that cycle-specific discharge plans ensure the fuel pool will be adequately cooled. However, there is an inconsistency between the UFSAR statement about a cycle-specific analysis ensuring the pool will be below 150°F, and the design basis of 140°F for normal refueling (batch or full-core).
Also, the design basis temperature for a batch refueling with a single failure is 150°F, but the UFSAR statement does not mention a single failure. We are seeking more detailed information on how the licensee will operationally ensure the cooling capability is adequate to meet all the design bases limits.
Section 10.5.3 of the PBAPS UFSAR, Revision 26 (April 2017), includes the following statement with respect to the timing of refueling discharges from the reactor to the spent fuel pool (SFP):
Since each refueling offload is cycle specific, then the variations in the number of fuel assemblies discharged, the incore decay time, the fuel assembly transfer rate and the power history can vary as long as analysis shows that the spent fuel pool bulk temperature will not exceed 150°F and localized boiling will not be expected to occur.
Similar to the PBAPS UFSAR statement, Section 6.3.1, "Fuel Pool Cooling," of the TSAR (i.e., Attachment 5 to the application) states the following with respect to the timing of refueling discharges:
The SFP cooling and makeup adequacy is maintained by controlling the timing of the discharge (fuel offload) to the SFP to ensure the capability of the FPCCS
[fuel pool cooling and cleanup system] to maintain adequate fuel pool cooling for the TPO uprate.
However, Table 10.5.2, "Summary of Cooling System Analysis Results," of the PBAPS UFSAR indicates that the maximum SFP temperature is 140°F for the normal refueling and full-core offload (with residual heat removal system cooling assist) cases with full cooling capability, and 150°F only for the single failure of a fuel pool cooling and cleanup system component. Similarly, Table 6-7 of the TSAR indicates that the maximum SFP temperature for normal refueling and full-core offload is 140°F, except the temperature for the full-core offload at 1.02 times the current licensed thermal power would be 141°F.
The analyses submitted under 10 CFR 50.34 include the final safety analysis report (FSAR) submitted under 50.34(b) as part of the application for an operating license. The FSAR includes information that describes the facility, presents the design bases and the limits on its operation, and presents a safety analysis of the structures, systems, and components and of the facility as a whole. As provided in 10 CFR 50.90, whenever a holder of an operating license desires to amend the license, application for an amendment must be filed with the Commission fully describing the changes desired, and following as far as applicable, the form prescribed for
MUR LAR Supplement 2 Responses to Requests for Information Attachment Page 5of14 original applications. In determining whether an amendment to a license will be issued to the applicant, 1 O CFR 50.92(a) states that the Commission will be guided by the considerations that govern the issuance of initial licenses to the extent applicable and appropriate. Consistent with the requirements indicated above, clarify how the timing of the refueling discharges would be controlled to ensure the design basis temperature limit for normal refueling and full-core offloads of 140°F would not be exceeded.
RESPONSE
PBAPS utilizes plant procedures RT-R-019-901-2(3), "Fuel Pool Heat Load Calculation," that require that a cycle-specific estimation of decay heat be calculated based on the number of assemblies off-loaded, estimated total decay heat, and a conservative estimation of the completion time of the off-load. Use of these procedures enables and directs operators to control the timing of spent fuel transfers from the reactor to the pool to ensure that the maximum spent fuel pool bulk temperature is maintained below the 150°F UFSAR temperature limit.
The text from UFSAR section 10.5.3 quoted in the RAI describes 150°F as the not-to-exceed bulk pool temperature for either a full or a normal core offload. The 150°F limit is also shown in Table 6-6 of Attachment 5 of the MUR License Amendment Request (LAR) and is the design basis temperature limit for normal refueling and full-core offloads. Analyses of the normal and full core off-load with full cooling capability cases were also performed to demonstrate compliance with the requirement in the NRC's EPU application document RS-001, "Review Standard for Extended Power Uprates." The 140°F temperature shown for these cases is the RS-001 analysis SFP temperature criterion, but is not the design basis temperature limit for PBAPS.
The results from the analysis of three SFP cooling scenarios performed for EPU conditions and presented in UFSAR Table 10.5.2, demonstrate compliance with that 150°F SFP limit, but do not provide new or additional design basis limits for the SFP. As with the analysis results shown at Extended Power Uprate (EPU) conditions in the UFSAR, the results of these same three analyses in Table 6-7 of MUR LAR Attachment 5 continue to demonstrate compliance with the UFSAR 150°F SFP limit and meet the guidance in the SFP cooling acceptance criteria of RS-001, but at MUR conditions. Following NRC approval of this LAR, these TSAR analysis results will be incorporated into the UFSAR Table 10.5.2 as part of the planned UFSAR update process.
EEOB-RAl-1 In Section 6.1.1, "Off-Site Power," of the TSAR, the licensee states "[t]he main generator will be operated within the existing generating capability curve at TPO. For summer and winter operations, the gross generator MWe output will be kept on, or within, the existing generator reactive capability curve." Table 6-2, "Main Generator Ratings Comparison," of the TSAR provided the following ratings for the PBAPS main generator: 1,408 megawatts electric (MWe) for Unit 2 and 1,377 MWe for Unit 3 at TPO RTP conditions. In Section 7.1, "Turbine-Generator," of the TSAR, the licensee stated that the main generator was projected to produce an electrical power output of approximately 1,387.9 MWe at TPO RTP.
The NRC staff noted that the projected electrical power output (1,387.9 MWe) for the main generator exceeds the generator rating (1,377 MWe) for Unit 3.
MUR LAR Supplement 2 Responses to Requests for Information Attachment Page 6of14
- a. Explain how the main generator for Unit 3 will operate within its generating capability curve if its electrical power output is higher than its electrical rating; and discuss the impact of the higher electrical output on the main generator and its protective devices. Also, provide the gross generator output in MWe for the summer and winter operations for Units 2 and 3, as well as the main generator capability curve for both Units 2 and 3. Using the main generator capability curve for both Units 2 and 3, provide a discussion to demonstrate that the generator will continue to operate within the limits of its capability curve.
- b. Table 6-2 of the TSAR shows a 1,530 megavolt amperes (MVA) rating for the main generator in each PBAPS unit. Provide the MVA loadings for the Unit 2 and Unit 3 main generators at TPO conditions and provide a discussion that demonstrates the main generators are adequately sized to support TPO uprate operations.
RESPONSE
Main generators on both Units are rated at 1530 MVA, but with design points at different power factors. The Unit 3 design point at 0.90 power factor (PF) corresponds to 1377 MWe and 667 megavolt amperes-reactive (MVAR) The Unit 2 design point at 0.92 PF corresponds to 1408 MWe and 600 MVAR. The generator capability curves for Units 2 and 3 are shown in Figures 1 and 2 below.
The projected gross generator output for both Units 2 and 3 at licensed TPO power level is approximately 1388 MWe (winter operation) and 1323 MWe (summer operation). Both PBAPS Units typically operate at a power factor exceeding 0.98, and historical data since January 2014 shows the lowest operating power factor to be approximately 0.945. At this power factor (0.945) and maximum TPO winter output (1388 MWe), the generator would operate at 1469 MVA and 481 MVAR. This maximum projected operating point is within the generator capability curves for both Units. Additionally, station operating procedures ensure the main generators are operated within the limits of the generator capability curves at all times, regardless of grid MVAR demand and Unit MWe output. The electrical output and impact on generator protective devices is currently being evaluated for TPO. If necessary to support the increased generator MWe output with the TPO uprate, generator protective relay settings will be changed in accordance with Exelon's configuration control program.
MUR LAR Supplement 2 Attachment Page 7of14 Responses to Requests for Information
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- b. The projected gross generator output for both Units 2 and 3 at licensed TPO power level is approximately 1323 MWe (summer operation) and 1388 MWe (winter operation). At the lowest historical power factor (0.945), the generators would operate between 1400 MVA (summer operation) and 1469 MVA (winter operation). Typically, the generators' MVA loadings would be much less than this, with operation at power factors above 0.98. These MVA loadings are below the 1530 MVA generator rating.
EEOB-RAl-2 In Table 6-1, "Plant Electrical Equipment Ratings," of the TSAR, the licensee provided the ampere ratings for the isolated phase bus duct (generator bus, main section, delta section, and auxiliary section). Section 6.1.1 of the TSAR states that the isolated phase bus duct is adequate for both rated voltage and low voltage current output.
2000
MUR LAR Supplement 2 Responses to Requests for Information Attachment Page 9of14 Provide the TPO uprate loadings for the generator bus, main section, delta section, and auxiliary section of the isolated phase bus and provide a discussion that demonstrates the isolate phase bus duct is adequately rated for TPO uprate conditions.
RESPONSE
The table below lists the ratings of the lsophase Bus Duct (IPBD) sections and the load values at the maximum rated generator output of 1530 MVA. These load values at maximum rated generator output bound the projected load values at TPO operation. The load values at 1530 MVA remain within the ratings of the individual IPBD sections.
IPBD Section Rating (Amps) 1530 MVA load (Amps)
Generator Bus 21,200 21, 133 Main Section 42,300 42,267 Delta Section 24,500 <1l 24,403 Auxiliarv Section 2,000 1,255
<1> Note that TSAR Table 6-1 lists the rating of the IPBD Delta Section as 20,500 amps. This was a typographical error in the TSAR. The original rating of the IPBD Delta Section was 20,500 Amps; however, the rating was increased to 24,500 Amps with IPBD replacement in support of the EPU.
This error is being processed in the Corrective Action Program.
EEOB-RAl-3 In Section 6.1.1 of the TSAR, the licensee stated that the grid voltage analysis for the PBAPS TPO uprate, which was performed by PECO, verified the transmission system's capability to maintain the post-trip voltage drops and voltages at the safety buses above the reset value of the degraded voltage relay (DVR) on a steady-state basis. The PECO grid voltage analysis report for PBAPS Units [2 and 3] TPO uprate is provided in Attachment 13 of the license amendment request.
Provide the reset voltage of the DVR on a steady-state basis, and using two results of the simulated worst-case voltage drops and voltages provided in Section 3, "Study Results," of 3, provide a discussion that demonstrates the transmission system will maintain the post-trip voltage drops and voltages at the safety buses above the reset value of the DVR at TPO operating conditions.
RESPONSE
The DVR reset voltage is 3856 V. PBAPS procedure SE-16, "Grid Emergency," provides the maximum post trip contingency percentage voltage drop for each offsite source. These voltages are obtained from the "Peach Bottom Voltage Regulation Study." As long as the post-trip contingency percentage voltage drops are less than these limits under accident conditions, the DVRs do not time out and cause the safety related buses to be separated from the offsite sources.
For all three offsite sources, the voltage drops in the PECO grid voltage analysis (MUR LAR 3) are less than the maximum post trip contingency percent voltage drop in procedure SE-16 at TPO conditions (see table below). Therefore it can be concluded that under the worst case offsite source voltage drops as predicted in the PECO grid voltage analysis, the
MUR LAR Supplement 2 Responses to Requests for Information Attachment Page 10of14 PBAPS safety buses will remain connected to the offsite source(s). Additionally, the analyzed station electrical distribution system house loads are not increasing as a result of MUR. This conclusion remains the same during operation at the TPO power level.
Source PECO Max Volt.
SE-16 Max Volt Drop Post MUR Drop 2SU 0.7%
1.2%
3SU 1.2%
1.5%
3438U 1.1%
1.3%
EEOB-RAl-4 In Section 9.3.2 of the TSAR, the licensee stated that the station blackout (880) event was previously analyzed for the extended power uprate EPU, and a plant-specific analysis was performed to confirm continued compliance to 1 O CFR 50.63 at TPO RTP conditions. The licensee did not provide the above-mentioned plant-specific analysis. The NRC staff notes that the current SBO analysis for PBAPS was evaluated at 100% of the current licensed thermal power level (i.e., 3,951 MWt), as stated in UFSAR Section 5.2.4.3.1.
Since the licensee proposed to increase the PBAPS thermal power to approximately 4,016 MWt (approximately 1.66% increase in RTP), provide a summary of the plant-specific SBO analysis for the proposed MUR thermal power (4,016 MWt) and provide a discussion of how PBAPS continues to meet 1 O CFR 50.63.
RESPONSE
A plant specific analysis was performed at a bounding power level of 4,018 MWt for an 880 event, which demonstrates continued compliance with the SBO event analysis requirements using the guidelines of NUMARC 87-00 and Regulatory Guide 1.155. The results of this evaluation are described below.
The major characteristics that affect the ability to cope with a 880 event are identified in NUMARC 87-00 Revision 1 as:
- 1. Condensate inventory for decay heat removal
- 2. Class 1 E battery capacity
- 3. Compressed gas capacity
- 4. Effects of loss of ventilation
- 5. Containment isolation system operability By satisfying the criteria used in assessing the above characteristics, the plant is able to show satisfactory response to an SBO event.
NU MARC 87-00 Revision 1 provides two methods for conducting the assessment. The second method, the Alternate AC Approach, is the current licensing basis for PBAPS and was used in the PBAPS SBO assessment. The alternate AC Approach is the method for calculating the coping period where the plant uses equipment that is capable of being electrically isolated from
MUR LAR Supplement 2 Responses to Requests for Information Attachment Page 11of14 the preferred off-site and emergency on-site AC power sources. The eight-hour coping duration criteria for Alternate AC Approach plants applies to PBAPS. Thus, PBAPS must meet the SBO requirements for at least eight hours.
Condensate Inventory for Decay Heat Removal Analyses have shown that the PBAPS condensate inventory is adequate to meet the SBO coping requirement for TPO conditions. The current Condensate Storage Tank inventory reserve for the Reactor Core Isolation Cooling (RCIC) and High Pressure Coolant Injection (HPCI) systems' use ensures that adequate water volume is available to remove decay heat, depressurize the reactor and maintain reactor vessel level above the top of active fuel during the coping period at TPO conditions.
Class 1 E Battery Capacity Evaluation of the PBAPS Class 1 E Battery capacity has shown that PBAPS has adequate battery capacity to support decay heat removal during a station blackout for the required coping duration. The battery capacity remains adequate to support RCIC and HPCI systems' operation at TPO conditions.
Compressed Gas Capability PBAPS meets the requirement for compressed gas capacity. An evaluation has shown that the PBAPS pneumatically operated safety relief valves (SRVs) required for decay heat removal have sufficient compressed gas capacity for the required automatic and manual operation during the station blackout event for TPO conditions. Sufficient capacity remains to perform emergency Reactor Pressure Vessel (RPV) depressurization in case it is required.
Effects of Loss of Ventilation The effect of loss of ventilation in the dominant areas of concern containing equipment necessary to achieve and maintain safe shutdown during a station blackout was evaluated for TPO conditions. The SBO environment conditions do not change significantly after TPO, and containment isolation for SBO remains acceptable. The evaluation shows that equipment operability is maintained because the SBO environment is milder than the existing design and qualification bases. The areas evaluated for PBAPS included:
Control Room and Cable Spreading Room Switchgear Room/Inverter Room Drywell RCIC Room HPCI Room Containment Isolation System Operability Containment isolation capability is not adversely affected by the SBO event for TPO as the SBO environment conditions do not change significantly after TPO, and containment isolation for SBO remains acceptable.
The plant response to and coping capabilities for an SBO event are shown in the following table.
The events listed are unchanged from the EPU analysis and the event times are affected slightly by operation at TPO due to the increase in the initial power level and decay heat. The decay heat is based upon the nominal ANSI/ ANS 5.1-1979 standard consistent with the recommendations of General Electric Service Information Letter (GE SIL) - 636 with initial decay
MUR LAR Supplement 2 Responses to Requests for Information Attachment Page 12of14 heat at 100% equilibrium and metal water reaction is not modeled. There are no changes to the systems and equipment used to respond to an SBO event, nor is the required coping time of eight hours changed at TPO conditions.
PBAPS 2 & 3 Station Blackout Sequence of Events for TPO Time (sec)
Description
-o Loss of Offsite Power Reactor scram MSIV start to close Loss of Feedwater Loss of Service Water RCIC available to maintain reactor water level HPCI available to maintain reactor water level 3.5 MSIV closed 5
Feedwater flow stops
-9 to 25 SRVs open (relief mode) 55 Begin HPCI Injection 94 Begin RCIC Injection 127 End HPCI and RCIC Injection 588 Begin HPCI and RCIC Injection 662 End HPCI and RCIC Injection 1,312 Begin HPCI and RCIC Injection 1,382 End HPCI and RCIC Injection 1,800 Begin RPV pressure control using subsequent SRV operation 2,067 Begin RCIC Injection 3,600 Alternate AC available 5,400 Begin Suppression Pool Cooling (SPC) 5,700 End SPC (LOCA signal) 6,304 Begin SPC
-8800 RCIC suction source swapped to Suppression Pool 10,661 End RCIC Injection End SPC (Opposite Unit LOCA signal)
Beoin LPCI injection 11,261 SPC available (End 10 minute LOCA interruption) 11,305 Begin Alternate Shutdown Cooling (ASDC) 28,800 End of Copino Period 28,800 End LPCI Injection
MUR LAR Supplement 2 Responses to Requests for Information Attachment Page 13of14 The key parameters for the SBO calculations for containment response at Current Licensed Thermal Power (CL TP) conditions, TPO conditions, and the design limits are provided in the following table.
Parameter Units CL TP (3951 MWt)
TPO (4018 MWt)
Design Limit Peak Drywell Pressure psi a 40.4 40.7
<70.7 Peak SP (Torus)
OF 199 200
<281 Temperature Based on a plant-specific evaluation of the plant's ability to cope with and recover from an SBO event for the period of time established in the plant's licensing basis at TPO conditions, Exelon concludes that the plant will continue to meet the requirements of 10 CFR 50.63 following implementation of the proposed TPO uprate.
EEOB-RAl-5 In Section 10.3, "Environmental Qualification," of the TSAR, the licensee provided the evaluation for some but not all of the environmental conditions (e.g., temperature, pressure, and humidity) reviewed for safety-related electrical equipment to ensure that the existing qualification for the normal and accident conditions expected in the area where the equipment is located remain adequate.
Discuss the impact of the TPO uprate on 1) the normal pressures inside containment, 2) the normal temperatures and pressures outside containment, and 3) the humidity levels inside and outside containment for normal and accident conditions.
RESPONSE
Normal pressure inside containment Since the TPO uprate does not increase the normal vessel dome pressure, it will have a negligible effect on normal temperature and pressures inside containment. The pressure inside containment at TPO conditions will remain bounded by the existing pressures specified for use in the Environmental Qualification (EQ) program.
Normal pressure and temperature outside containment Since the TPO uprate does not increase the normal vessel dome pressure, it will have a negligible effect on normal pressures and temperatures experienced by equipment outside containment. Temperature, pressure, and humidity values for normal operating conditions are maintained by the normal Heating, Ventilation and Air Conditioning (HVAC) systems. The data presented in the PBAPS environmental qualification specification for normal conditions was initially based on a collection of plant data, and is routinely validated for the Reactor Building through a review of plant surveillances. The pressures and temperatures outside containment at TPO conditions will remain bounded by the existing environmental parameters specified for use in the EQ program.
MUR LAR Supplement 2 Responses to Requests for Information Normal and accident humidity levels Attachment Page 14of14 Temperature, pressure, and humidity values for normal operating conditions are maintained by the normal HVAC systems, and will remain within the existing parameters specified for use in the EQ program. Qualification for normal humidity conditions is bounded by the qualification for accident conditions. For accident conditions, the equipment inside and outside containment is qualified to a 100% relative humidity level, and therefore the current qualification is bounding of TPO conditions.
Summary The normal conditions expected in areas containing environmentally qualified equipment remain adequate at TPO conditions, and will remain within the ranges provided in the PBAPS environmental qualification specification. The qualification of equipment for accident conditions in terms of humidity is unaffected by the TPO uprate.