ML20135E655
| ML20135E655 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 12/02/1996 |
| From: | Subalusky W COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML19310D739 | List: |
| References | |
| TAC-M87076, TAC-M88625, TAC-M91926, TAC-M93915, NUDOCS 9612110397 | |
| Download: ML20135E655 (16) | |
Text
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I.asalle Gen < rating Mation 2001 North 21st Road
%1arwilln. 11613614'5' Tel H I 4 357 ~61 December 2,1996 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555
Subject:
LaSaile County Nuclear Power Station Units 1 and 2 Request for Technical Specification Amendment Facility Operating Licenses NPF-11 and NPF-18 Safety / Relief Valve Permanent Removal NRC Dockets Nos. 50-373 and 50-374 Pursuant to 10 CFR 50.90, Comed proposes to amend Appendix A, Technical Specifications, of Facility Operating Licenses NPF-11 and NPF-18, and requests that the Nuclear Regulatory Commission (NRC) grant an amendment to Section 3.4.2 to revise the safety / relief valve (SRV) configuration to include only 13 (12 required operable) of the current 18 (17 required operable) SRVs.
Portions of this proposed amendment closely resemble the amendments approved for Unit 1 (TAC No. M93915, January 3,1996) and Unit 2 (TAC No. M91926, April 25,1995), which increased the SRV safety function lift setting tolerance from +1%/-3% to 13% Additionally, Washington Public Power Supply System previously neceived approval (TAC Nos. M87076 and M88625, May 2,1995) for operation with six SRVs out-of-service, SRV setpoint tolerance relaxation, and power uprate, which was requested in a comt"ned submittal.
This proposal will have a minimum impact on safety. The change has been justified by an ASME Overpressurization analysis, an ATWS analysis and verification that this remains applicable for the introduction of Siemens fuel, reviews of high pressure system performance, an evaluation of LOCA containment response, and an evaluation of SRV reliability, all of which have been performed by General Electric (GE). In addition, Sargent and Lundy, who has the current design authority for piping loadings at LaSalle, has performed analyses to evaluate the revised piping for the main steamlines and the SRV tailpipes. Comed has also evaluated the impact of this change on Minimum Critical Power Ratio, the Loss-of-Coolant Accident analysis of 9612110397 961202 1 PDR ADOCK 05000373 P PDR W l un,mnomwm fg%\ \t>[$)
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i record, and Emergency Procedure Guidelines. The combination of these above analyses constitutes an evaluation consistent with GE's evaluation of the required elements to be considered in SRV removal. This was based, in I part, on the BWR Owner's Group (BWROG) Licensing Topical Report for SRV setpoint tolerance relaxation (reference 3, Attachment A), which affects ,
many of the same design bases as SRV removal. Additional areas have I been evaluated which specifically address the structural and reliability elements of SRV removal.
The ATWS analysis included in this submittal was performed using GE's ODYN methodology, which is currently approved for use in evaluating cycle- !
specific pressurization events. Use of this methodology will reserve margin i for a planned future power uprate. Comed believes use of ODYN to analyze this event is a natural extension of its approval for evaluating cycle-specific l pressurization events, and requests NRC approval to use ODYN for analyzing ATWS peak pressures.
Prior to the earlier SRV setpoint tolerance relaxation amendments, Comed was in the process of preparing an amendment package requesting the i3% ,
setpoint tolerance increase in conjunction with a reduction in the number of '
installed SRVs for Units 1 and 2. However, the setpoint tolerance increase alone was sought and approved to support the Unit 2 Refuel Outage 6 SRV testing activities, and was also subsequently approved for Unit 1. In this current requested amendment, the reduction of fiva SRVs per unit is requested. Due to the original plan of a joint submittal, the attached GE analyses were performed with both the setpoint tolerance increase and a reduced number of SRVs. The analyses are applicable for requesting SRV removal, as both units currently have the setpoint tolerance relaxation approved.
The reduction in the number of installed SRVs reduces the number required to be removed, tested, and reinstalled each outage. This results in a savings in worker dose of 5 man-rem per outage, or more than 70 man-rem over the life of the two units. SRV testing and removal / installation savings amount to $128,000 per outage, or over $1.8 million over the life of the two units. Additionally, SRV removal reduces the number of solenoids, lift indicating switch assemblies (LISA) and linear variable displacement transducers (LVDT) that need to be replaced due to end-of-life considerations. This amounts to $375,000 in parts and labor savings over the life of the plant. The total estimated savings is $2.175 million and qualifies this amendment request as a Cost Beneficial License Amendment (CBLA).
This proposed amendment request is subdivided as follows:
- 1. Attachment A provides a description and safety analysis of the proposed changes in this amendment.
- 2. Attachment B includes a summary of the proposed changes and the marked-up Technical Specifications pages for LaSalle Unit 1 and 2 with the requested changes indicated.
- 3. Attachment C describes Comed's evaluation performed in accordance with 10CFR50.92(c), which confirms that no significant hazard consideration is involved.
- 4. Attachment D provides an Environmental Assessment Applicability Review per 10 CFR 51.21. !
- 5. Attachment E is the General Electric SRV Setpoint Tolerance Relaxation Analysis for LaSalle Units 1 and 2.
- 6. Attachment F is a withholding affidavit for the GE SRV Reduction /Setpoint Tolerance Relaxation Analysis Report.
- 8. Attachment H is the Sargent and Lundy analysis supporting the increased main steam piping loads.
- 9. Attachment I is a non-proprietary version of the GE Analysis presented in Attachment E.
This request for a Technical Specification Amendment has been reviewed and approved by On-Site and Off-Site Review in accordance with Comed procedures. Additionally; Comed engineering has performed reviews of the vendor analyses included with this submittal.
The attached General Electric SRV Reduction /Setpoint Tolerance Relaxation Analysis Report contains information proprietary to General Electric Company. In accordance with the requirements of 10CFR 2.790(b),
an affidavit for this report is enclosed as Attachment F to support the withholding of this report from public disclosure. In addition, a non-proprietary version (Attachment I) of the report is being transmitted.
Comed requests that NRC review of this proposed amendment be completed by September 26,1997, which is 3 weeks prior to the current schedule for Unit 1 Cycle 8 shutdown. This will allow for the removal modifications to begin with assurance that this request is approved.
Implementation would be prior to startup for L1C9 for Unit 1 and L2C9 for Unit 2.
Comed is notifying the State of Illinois of this application for amendment by transmitting a copy of this letter and its attachments to the designated state official.
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( If there are any questions or comments concerning this letter, please refer l l them to Perry Barnes at (815) 357-6761, extension 2383.
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l Respectfully, l
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l W. T. Subalusky Site Vice President :
LaSalle County Station Enclosure '
cc: A. B. Beach, NRC Region lli Administrator ;
M. P. Huber, NRC Senior Resident inspector - LaSalle t
D. M. Skay, Project Manager - NRR - LaSalle F. Niziolek, Office of Nuclear Facility Safety - IDNS l
DCD - Licensing (Hardcopy: Electronic: ) ,
Central File !
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1 STATE OF ILLINOIS COUNTY OF LASALLE Docket Nos. 50-373 IN THE MATTER OF 50-374 COMMONWEALTH EDISON COMPANY LASALLE COUNTY - UNITS 1 & 2 AFFIDAVIT l affirm that the content of this transmittal is true and correct to the best of my knowledge, information and belief.
y O)NK , A 3, W. T. Subalusky, Jr. (.
j.- k Site Vice President LaSalle County Station Subscribed and sworn to before me, a Notary Publig and i
for tt)e State and County above named, this cR day of Awdzev .19 96 My Commission expires on Cefi/xs / . 49.dno .
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OFFICIAL SEAL:=====:======,!
LAURIE J ALLEN l
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' 2&ea Notary Public /
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t ATTACHMENT A DESCRIPTION AND SAFETY ANALYSIS OF THE PROPOSED CHANGES DESCRIPTION OF THE PROPOSED CHANGE l
l This Technical Specification Amendment request proposes to amend Appendix A, Technical Specifications, of Facility Operating Licenses NPF-11 and NPF-18, i Section 3.4.2 and Bases Section 3/4.4.2 to revise the Unit 1 and Unit 2 safety / relief valve (SRV) configuration, and delete 5 of the 18 SRVs currently installed in each unit. One of the remaining 13 SRVs of each unit would not be required to be operable, retaining LaSalle's one SRV out-of-service option.
DESCRIPTION OF THE CURRENT OPERATING LICENSE / TECHNICAL SPECIFICATION REQUIREMENT The LaSalle Unit 1 and 2 Technical Specifications (Section 3/4.4.2) provide required safety valve function pressure lift settings for the 18 SRVs. Only 17 SRVs are required to be operable.
BASES FOR THE CURRENT OPERATING LICENSE / TECHNICAL SPECIFICATION REQUIREMENT The SRVs prevent vessel overpressurization both in the relief and safety modes of operation. Peak vessel pressures occur during both the ASME Overpressurization Event and Anticipated Transients Without Scram (ATWS).
In the ASME Overpressurization Event, peak vessel pressures must remain below the upset transient limit of the ASME Code (1375 psig), and only the safety function of the SRVs is credited. Previous reload analyses of this event have been performed crediting 17 of the 18 installed SRVs. During an ATWS, the peak vessel pressure must remain below the emergency limit of the ASME Code (1500 psig), and the relief mode of the SRVs is credited. This analysis was performed as a generic bounding analysis, versus a cycle-specific analysis.
Results of this analysis are summarized in UFSAR Section 15. Cycle-specific transient analyses that are performed to determine the Operating Limit Minimum l
Critical Power Ratio (OLMCPR) credit the SRV relief function for the required number of SRVs given in Section 3/4.4.2.
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DESCRIPTION OF THE NEED FOR AMENDING THE TECHNICAL SPECIFICATIONS The reduction in the number of installed SRVs reduces the number required to be removed, tested, and reinstalled each outage. This results in a savings in worker dose of 5 man-rem per outage, or more than 70 man-rem over the life of the two units. SRV testing and removal / installation savings amount to over
$128,000 per outage, or more than $1.8 million over the life of the two units.
Additionally, SRV removal reduces the number of solenoids, lift indicating switch assemblies (LISA) and linear variable displacement transducers (LVDT) that need to be replaced due to end-of-life considerations. This amounts to
$375,000 in parts and labor savings over the life of the plant. The total estimated savings is $2.175 million and qualifies this amendment request as a Cost Beneficial License Amndment (CBLA).
DESCRIPTION OF THE AMENDED TECHNICAL SPECIFICATION REQUIREMENT The requested change would delete the 5 valves from each unit corresponding to the following safety function lift settings: 2 @ 1185 psig,1 @ 1195 psig and 2
@ 1205 psig (See Figure 1). None of the valves to be eliminated are part of the Automatic Depressurization System (ADS), and none have Low-Low Set (LLS) or Remote Shutdown Panel functions. Therefore, the SRVs remaining will be 2
@ 1205 psig,3 @ 1195 psig,2 @ 1185 psig,4 @ 1175 psig and 2 @ 1150 psig.
Twelve of the remaining thirteen SRVs would be required to be operable.
BASES FOR THE AMENDED TECHNICAL SPECIFICATION REQUIREMENT Because of the changed SRV configuration, several analyses and evaluations have been performed by General Electric (GE), Sargent and Lundy (S&L), and Comed to verify adequate safety and design margins are maintained. The requirements that need to be considered for SRV elimination are similar to those that were considered previously for SRV safety mode setpoint tolerance relaxation. Comed's previous approved amendments (references 1 and 2) for setpoint relaxation followed the requirements provided in the BWR Owner's Group (BWROG) Licensing Topical Report for SRV setpoint tolerance relaxation (reference 3).
l With the proposed SRV removals, the two SRVs with the lowest set pressures are being maintained. These have safety mode settings of 1150 psig. By maintaining the lowest setpoints, several of the BWROG requirements need not be re-evaluated. This is discussed below in the applicable sections. However, by physically removing the SRVs, several new areas are evaluated that were not A-2
l previously mentioned in the setpoint tolerance relaxation submittals. These are also discussed below.
l The Attachment E GE report is a combined SRV removal /setpoint tolerance I
relaxation analysis. Therefore, some of the sections of the GE report are sections previously approved in the setpoint tolerance relaxation submittals and are not areas requiring consideration for SRV removal. This is pointed out, where applicable, in the following sections.
- 1. ASME Overpressurization Event General Electric has performed an analysis (Attachment E) of the ASME Overpressurization Event (MSIVF) assuming 10 of the 18 currently installed (17 required operable) SRVs were available. The additional SRV removals are conservative with respect to the actual number being requested for elimination.
Assuming additional SRVs do not function provides a higher peak pressure ,
value than would be obtained assuming only 5 were removed (with one out-of-service). ,
However, this analysis only serves as a sensitivity study, as this analysis is required to be performed each cycle. A specific analysis using the L1C9 neutronics parameters will be performed and verified to be acceptable through !
the 10CFR50.59 reload licensing process as usual, prior to L1C9 startup. The :
same process will be used for L2C9 and all subsequent startups. These analyses will be performed using Siemens Power Corporation's NRC-approved COTRANSA-2 methodology and verified through 10CFR50.59 to meet the required ASME code limit prior to startup. Approval for use of COTRANSA-2, and use of all required SPC reload methodologies for LaSalle, has been obtained in the Reference 5 SER.
The MSIVF analysis assumes that, upon closure of the MSIVs, the reactor is shut down by the high neutron flux scram. SRVs in the safety mode are used to mitigate the pressure increase. Credit is not taken for the relief mode of operation or the direct MSIV position scram. The GE analysis assumes a 102%
power /105% flow condition, which supports LaSalle's current ability to operate in the extended operating domain and increased core flow regions.
The analysis was performed using ODYN, the GE thermal-hydraulic and nuclear kinetics coupled transient code. This is the NRC-approved methodology for this event.
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i The peak vessel pressure calculated in the GE MSIVF analysis is 1341 psig. l This provides sufficient margin to the ASME upset code limit of 1375 psig. Table :
3-2 and Figure 3-1 of Attachment E give detailed results of the transient !
response for this event. For illustrative purposes, Table 3-2 shows both the new l analysis and the old L2C7 reload MSlVF analysis results, which credited 17 l
SRVs and also assumed the earlier safety mode setpoint tolerance of +1%. -
- 2. High Pressure System Performance !
The Attachment E GE analysis also includes evaluations of High Pressure l System Performance. This portion of the report is applicable only to increasing the setpoint tolerance, which as mentioned earlier, has already been approved j for both LaSalle units. High pressure system performance would only be '
impacted due to SRV removals if the lowest setpoint SRVs were eliminated.
However, Comed is proposing to maintain the lowest SRVs, so these additional analyses are not required as the maximum injection pressure for these systems is unchanged.
- 3. Containment Dynamic Loads GE has analyzed the impact of the proposed SRV removals on containment response during a LOCA (Attachment E). GE concluded that during a Design Basis Accident LOCA there is no impact on containment pressure and temperature and the peak suppression pool temperature since the vessel depressurizes without any SRV actuation.
For smaller breaks, the vessel remains at high pressure for a longer time period, which can result in high drywell temperature conditions. When the vessel pressure reaches the SRVs relief mode opening setpoints, the SRVs will actuate to control the vessel pressurization. Although the initial mass and energy release to the drywell will be slightly higher, the total integrated release will remain the same, as the decay heat and vessel fluid energy are not changed d with SRV removals.
Local suppression pool temperatures have also been evaluated by GE in Attachment E. When considering the worst case scenario of 6 adjacent SRVs not functioning (the analysis assumes 5 removed and 1 out-of-service), it is ;
found that there could be a slight increase in local temperatures. However, this would occur early in the event when all valves blow down and initial suppression pool temperatures are colder. This condition does not continue later in the event when suppression pool temperatures'are higher, because the valves actuate on Low-Low Set (LLS), and only one SRV will continue to actuate. The valves .
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proposed for elimination in this submittal do not include any of the current LLS valves, so this function is not impacted.
i LOCA hydrodynamic loads, such as pool swell, condensation oscillation and chugging are not impacted as pressure and temperature containment response l is not affected.
GE also evaluated hydrodynamic load distribution, submerged pool boundary and submerged structure loads in the Attachment E report. GE discussed the potential impact of the removal of 5 adjacent SRVs on load distribution in the suppression pool. This was considered even though the SRVs to be removed are not all directly adjacent to one another. The current asymmetric loading analysis assumes three adjacent SRVs discharge into the suppression pool.
This analysis remains valid for SRV removals as it is a local event.
The submerged pool boundary and submerged structure loads were evaluated by GE in Attachment E. These evaluations were required due to the earlier submittal to increase the SRV setpoint tolerance. For SRV removal, the SRV opening pressures are not impacted. As the opening pressures determine the loadings, these loadings are not changed with SRV removals.
- 4. Main Steam Piping Evaluation The modification to remove the SRVs would involve blank flanging the main steamline header connection, and pardslly cutting back and re-supporting the discharge piping. The main steamline header, capped tailpipes and tailpipe supports will continue to meet the same classification criteria as those applied previous to this modification.
I Sargent and Lundy (S&L) evaluated the impact of the SRV removals on main l steam piping (Attachment H). For this analysis, the computer code PIPSYS l (Piping Analysis information System), described in Appendix F of the FSAR, was utilized. In addition to considering the SRV removals, assumptions for a future power uprate, including new steamline mass flow, pressure, time and temperature profiles, and higher SRV set pressures, were included as input assumptions so the analysis would not need to be re performed for the potential future higher power conditions. The new loadings calculated with these assumptions are conservative compared to the current power level and SRV set pressures.
The systems evaluated were the four main steamline header subsystems, which include the SRV discharge piping down to the wetwell penetration anchors.
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These piping subsystems are the only ones affected by the proposed SRV !
removals. S&L determined that the modified piping was adequate to withstand the revised design basis loadings, and remains within the UFSAR stress !
allowables. The discharge lines below the wetwell penetration anchors and the !
T-Quenchers would not be impacted by SRV removals alone as the discharge pressure for each one remains unchanged and the pool loadings are the same.
These systems will be evaluated later when power uprate approval is sought to .
include the effects of the higher set pressures on the wetwell portion of the '
tailpipes. .
Each abandoned tailpipe has been designed and supported for the applicable loads, except for the SRV transient load, which is no longer a concern for the inactive tailpipes. .
For all piping evaluated, the design margins to the UFSAR stress allowables were found to be greater than or equal to 1.0. This ensures there is adequate i margin remaining between the allowed stresses and the calculated stresses under the new piping configuration. Additionally, structural framings were reviewed due to increased pipe support loads. These structural framings were found to meet the UFSAR allowables.
l For each abandoned discharge line, the snubbers installed to limit loading l forces will continue to be tested as is currently required by Technical
- Specification 3/4.7.9, or will be removed and replaced with struts. The results of the Attachment H analyses account for the vertical snubbers being changed to ,
l struts and the horizontal snubbers either being changed to struts, or remaining ?
in place. j With the new piping configuration, the Attachment H report indicates that 6 additional fitting welds will need to be inspected under the current in-Service -
Inspection (ISI) program. The weld points indicated in Attachment H will be added to LaSalle's ISI program, meeting inspection requirements as indicated in Reference 6.
- 5. Anticipated Transient Without Scram (ATWS) Mitigation Capability GE has reanalyzed (Attachment E) the Main Steam Isolation Valve Closure (MSIVC) event under ATWS conditions to support the requested SRV removals.
The MSIVC event is the limiting ATWS event. In this analysis, the Standby Liquid Control System (SLCS) provides eventual shutdown of the plant, and the
! initial reduction in reactor power is by the ATWS Recirculation Pump Trip. The analysis assumes 100% power /87% flow operating conditions and the current i
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I j approved setpoint tolerance relaxation. Although operation at 105% core flow is licensed for LaSalle, the 100% power /87% flow condition is limiting for this event. The analysis credits proper operation of 12 SRVs. This allows for one SRV out-of-service and the removal of five SRVs proposed with this submittal, i
- As an input assumption which serves only to add more conservatism to the l
! analysis, GE also assumes the relief function settings are increased by 30 psi !
I over the nominal values, although no change to the relief function tolerances is -
being requested by Comed. The relief function tolerance is currently 15 psi l above or below nominal. ;
i This event was analyzed for the short-term portion of the event, which verifies
- that the peak vessel pressure does not exceed the ASME emergency criterion of l
! 1500 psig. The long-term portion of the event, which includes boron injection is dependent on the initial energy produced by the core and the initial operating statepoint, and is not significantly affected by SRV removals (see Attachment E). l l The results of the GE analysis show that the peak vessel pressure is 1378 psig.
This is well within the ASME emergency criterion of 1500 psig.
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l The analysis for this event was performed using the one-dimensional ODYN computer code. The ODYN code is currently approved (Reference 12, Attachment E) for use in analyzing cycle-specific pressurization events. This approval also requires that if ODYN is to be used for ATWS or long-term i-transients, modifications to the code should be made. The current approved i methodology for performing ATWS analysis is REDY. However, as stated above, the portion of the ATWS event required to be analyzed for SRV removals is the short-term pressurization response. This portion of the event occurs prior to boron injection and reflects the ability of the vessel to depressurize.
l In the initial industry-generic ATWS analyses performed by GE in Reference 11 i of Attachment E (NEDE-24222), REDY results were submitted and subsequently i
, approved. However, prior to approval of the REDY results in this topical, GE ,
was required by the NRC, in Reference 14 of Attachment E, to compare the peak pressures calculated by REDY to those calculated by the then-unapproved ODYN code. These comparisons were provided to the NRC in Reference 11 of Attachment E. This topical report (NEDE-24222) was approved by the NRC with 7 these comparisons as a part of it. However, when ODYN was subsequently j approved for use in evaluating cycle-specific pressurization transients, approval was not given for use of this code in evaluating the ATWS event. GE had not sougSt approval of ODYN for analyzing the ATWS event, as NRC reviews of the event's long-term response and the boron injection modeling would have been
- necessary.
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GE has provided, in Reference 13 of Attachment E, supplementary information !
to the NRC as part of the Extended Power Uprate Program that evaluates the use of ODYN for both long-term and short-term ATWS evaluations. This information justifies applicability of the boron injection modeling. However, since j
the long-term response of the ATWS event is not re-evaluated with SRV - I removals, approval of the boron injection modeling, and the Extended Power l Uprate submittal, are not necessary for this application. ODYN need only be l allowed for calculating the peak vetssel pressure for the short-term ATWS pressure response. This is a logical extension of its current use in calculating i peak pressures for cycle-specific transients.
The use of ODYN for the short-term pressurization response of the event is more appropriate, since ODYN is a one-dimensional model, versus REDY's point kinetics modeling, so axial power variation is utilized by ODYN. Additionally, ODYN simulates pressure waves and improves the pressure rate and water level responses. Also, ODYN is the currently approved methodology for cycle-specific pressurization transients, which differ very little from this application. As the peak pressure comparisons between ODYN and REDY were submitted )
previously in the approved Reference 11 of Attachment E, further comparisons should not be required to allow the use of ODYN for evaluating the ATWS peak pressure in this submittal.
General Electric has evaluated the impact of Siemens fuel (Attachment G) on the ATWS event and determined that the application of Siemens fuel does not result in a significant impact to the ATWS analysis.
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- 8. SRV Availability l GE has evaluated, in Attachment E, the reliability of the SRVs in performing their !
safety mode function. This consideration was part of the initiel design criteria for ' i determining the number of valves that should be installed for each plant type. l This is a conservative intamal GE design evaluation which estimates the i probability that an MSlV Closure with Flux (MSIVF) Scran event occurs, j coincident with several SRV failures (2 in this case) so that the 1375 psig j criterion continues to be met. This reliability evaluation i1 not a Standard i Review Plan requirement, as SRV failures coincident vnth a MSIVF event are not i required to meet the 1375 psig criterion based on the expected probability of this j event. !
This GE evaluation takes into account the ASME Overpressurization Event l results and the potential failure rate of valves assumed to be in-service for this event. When accounting for potential failures of SRVs to perform their safety functions, industry experience in SRV failures is employed by GE to determine the probability of SRV failure-to-open. GE determined that the ASME ;
Overpressurization criteria will continue to be met with 12 SRVs available up to a l reliability factor of 0.999986. This is slightly outside the intemal GE criterion of I 0.99999, however as previously stated, there is no NRC commitment or SRP ;
requirement to meet this criterion, it is merely a conservative practice of GE's '
which allows them to design a plant with a high degree of certainty that future !
cycle core and fuel design variations will not result in the insertion of additional !
SRVs to meet the MSIVF event requirements. Comed has intemally evaluated the potential for future cycle variations and determined that enough margin .
remains to ensure no future SRV additions will be required.
- 7. Minimum Critical Power Ratio impact Comed has evaluated the impact of the SRV removals on Minimum Critical Power Ratio (MCPR) and concluded there is no adverse safety impact due to the proposed change. During the limiting reload licensing events for LaSalle, the MCPR occurs before the actuation of the lowest SRV setpoint. Analyses at off-rated conditions may result in SRV actuation before MCPR occurs, but the impact on ACPR is small. The cycle-specific Operating Limit MCPR will be ;
based on reload transient analyses that explicitly account for SRV removal for the licensed power to flow map. Results of these analyses will be documented in the cycle-specific reload licensing reports through the normal reload 10CFR50.59 process.
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SRV actuation is also required for UFSAR events which are not reload licensing events. These transients are not included in reload analysis and are not limiting ;
MCPR events because the core pressurization rates are slower and the power l transient is turned very quickly by scram reactivity. The transient ACPRs for !
these events are significantly lower than the ACPRs for the reload licensing events. SRV removnl will have a very small impact on MCPR, such that the l current reload licensing events remain limiting compared to the UFSAR pressurization events. i
- 8. LOCA impact In Reference 4, the LaSalle LOCA analysis of record, the limiting break is the double-ended recirculation suction line break. For the limiting break, the vessel pressure decreases immediately, and SRVs do not actuate. Thus, SRV removal has no impact on this case. Also, for other breaks, the Automatic Depressurization System (ADS) is assumed to operate along with other ECCS functions to mitigate the consequences. In the analysis,6 of 7 ADS valves are assumed to operate. The ADS is used to depressurize the vessel, which allows low pressure ECCS functions to operate.
With the introduction of Siemens fuel, a new LOCA analysis is being performed.
This analysis explicitly accounts for the 5 removed SRVs, in addition to 1 SRV Out-of-Service. This analysis is planned to be approved per 10CFR50.59 prior to the first startup with Siemens fuel (L2C8), although no SRVs will be removed until cycle 9 (the assumption of removed SRVs is conservative).
- 9. Emergency Procedure Guidelines
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The Emergency Procedure Guidelines instruct operators to actuate SRVs based on alphabetical order, Comed has evaluated the SRV removals to ensure no gross asymmetries will occur using this process and finds its continued applicability acceptable. Additionally, the GE asymmetric loading analysis for three adjacent SRVs bounds any small asymmetric perturbations this may cause.
The SRV Tail Pipe Lower Limit graph is used to instruct operators to initiate ADS prior to reaching this limit. This graph is not impacted, as it is applicable to ADS valves, none of which are removed with the proposed change. Therefore, no modifications to either portion of these guidelines are necessary with the proposed changes.
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SCHEDULE Comed requests that NRC review of this proposed amendment be completed by September 26,1997, which is 3 weeks prior to the current schedule for Unit 1 Cycle ,
8 shutdown. This will allow for the removal modifications to begin with assurance that this request is approved. Implementation would be prior to startup for L1C9 for Unit 1 and L2C9 for Unit 2.
REFERENCES. i
- 1. Issuance of Amendment No.108 for LaSalle County Station Unit 1, TAC No.
M93915, January 3,1996 l
- 2. lasuance of Amendment No. 89 for LaSalle County Station Unit 2, TAC No. ;
M91926, April 25,1995 l t
- 3. General Electric Company, "BWROG In-Service Pressure Relief ;
Technical Specification Revision Licensing Topical Report", !
NEDC-31753P, February 1990. 1
- 4. GE document, NEDC-32258P, "LaSalle County Station Units 1 and 2 SAFER /GESTR-LOCA Loss-Of-Coolant Accident Analysis", October, 1993.
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Nos. M95156 and M95157)", October 29,1996. l l l
- 6. "ASME Boiler and Pressure Vessel Code",Section XI, American Society l of Mechanical Engineers,1989 Edition.
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