ML20107M377
| ML20107M377 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 04/24/1996 |
| From: | Kraft E COMMONWEALTH EDISON CO. |
| To: | NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| ESK-96-063, ESK-96-63, NUDOCS 9604300354 | |
| Download: ML20107M377 (8) | |
Text
o Commonwralth 1.dison Company l
Quad Citics Generating Station 22710 206th Atenue North Cordova, II. 612 61r io i
Tel.kNM O2211 ESK-96-063 April 24,1996 Office of Nuclear Reactor Regulation l
U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Document Control Desk
Subject:
Quad Cities Nuclear Power Station Units 1 and 2 Plant Specific ECCS Evaluation Changes - 10CFR50.46 Report DPR-29 and DPR-30
_NRC Docket Nos. 50-254 and 50-265
Reference:
C. P. Patel of the Nuclear Regulatory Commission letter to D. L. Farrar dated August 4,1994, Transmitting Safety Evaluation Report for Core Spray Header Flaw at Quad Cities Unit 1 This letter fulfills the thirty day reporting requirement of 10CFR50.46(a)(3)(i) for Unit 1 of Quad Cities Nuclear Power Station because the effects of the installation of modifications to the Core Spray " Tee Box" and Core Shroud repairs performed this outage cause a change in calculated Peak Clad Temperature (PCT) difference of more than 50 F. This letter also fulfills the annual reporting requirement of 10CFR50.46(a)(3)(ii) for Unit 2 of Quad Cities Nuclear Power Station.
The Reference letter transmitted from the Nuclear Regulatory Commission is the most recent PCT change for Quad Cities Nuclear Power Station. Attachment 1 provides updated information regarding the PCT of the limiting Loss of Coolant Accident evaluations for Quad Cities Nuclear Power Station. This update includes changes not previously reported. As can be seen on, the net change in PCT is less than the 50 F reporting criteria. This report is i
required because the changes implemented during the current outage do exceed 50 F, though they are only partial components of the overall update. Attachment 1 includes all assessments as of April 3,1996 and updates both Quad Cities Units' calculated values. The assessment notes l
provide a detailed description for each change or error reported.
General Electric has evaluated issues which have resulted in PCT assessments to Loss of Coolant Accident (LOCA) analyses for Quad Cities Nuclear Power Station. General Electric and Comed have determined that these issues do not constitute substantial safety hazards, and that Quad i
Cities Nuclear Power Station continues to comply with the requirements of 10CFR50.46 and f
10CFR50 Appendix K acceptance criteria. Near term re-analysis is planned with the future transition to Siemens Power Corporation fuel.
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NRC Document Control Desk. April 24,1996 i
i Unit 2 will load Siemens fuel with the startup of Cycle 15 and apply the Siemens LOCA re-analysis to bound both units. Unit I willload Siemens fuel for the startup of Cycle 16.
If there are any questions or comments concerning this letter, please refer them to Nick Chrissotimos at (309) 654-2241, extension 3100.
Sincerely, O
/
e E. S. Kraft, Jr.
Site Vice President 3
Quad Cities Nuclear Power Station
' : Quad Cities 10CFR 50.46 Report cc:
H. J. Miller, Regional Administrator - RIII R. M. Pulsifer, Project Manager - NRR C. G. Miller, Senior Resident Inspector - Quad Cities Office of Nuclear Facility Safety - IDNS D. B. Tubbs, MidAmerican Energy Co.
R. J. Singer, MidAmerican Energy Co.
Quad Cities 10CFR 50.46 Report PLANT NAME:
Ouad Cities Unit !
ECCS EVALUATION MODEL:
Large Break LOCA REPORT REVISION DATE:
5/3/96 CURRENT OPERATING CYCLE: M ANALYSIS OF RECORD Evaluation Model: SAFER /GESTR - LOCA Calculation: General Electric document NEDC-31345P, Revision 2, dated July,1989 Fuel: P8x8R/BP8x8R which bounds GE8, GE9 and GE10 Reference PCT PCT = 1382 F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS LPCI injection delay to 75 seconds (Note 1) tPCT = +288 F Extended Operating Domain & Equipment OOS (Note 2) tPCT =
+10'F Safety Evaluation Report for Core Spray Header Flaw (Note 3) tPCT = +110'F Prior Assessments PCT PCT = 1790 F i
B. CURRENT LOCA MODEL ASSESSMENTS Replacement Access hole cover modification (Note 4) tPCT =
+10 F CS injection valve stroke time increased to 50 seconds (Note 5) tPCT =
+0'F Bottom Head Drain Flowpath (Note 6) tPCT =
+10 F Remove NRC SER requirement for Core Spray Header Flaw (Note 7) tPCT =
-110 F CS Tee Box repair including CS piping leakage (Note 8) tPCT =
+40 F Jet Pump Riser repair penalty (Note 9) tPCT =
+20 F Shroud repair including access hole cover (Note 10)
.tPCT =
+15 F.
Remove penalty for Replacement Access hole cover (Note i1) tPCT =
-10 F Total PCT Change from Current Assessments tPCT =
-25 F NET PCT PCT =
1765 F
h Quad Cities 10CFR 50.46 Report i
PLANT NAME:
Ouad Cities Unit 2 ECCS EVALUATION MODEL:
Large Break LOCA REPORT REVISION DATE:
5/3/96 CURRENT OPERATING CYCLE: 14 ANALYSIS OF RECORD Evaluation Model: SAFER /GESTR - LOCA Calculation: General Electric document NEDC-31345P, Revision 2, dated July,1989 Fuel: P8x8R/BP8x8R which bounds GE8, GE9 and GE10 Reference PCT PCT = 1382 F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS LPCI injection delay to 75 seconds (Note 1) tPCT = +288 F Extended Operating Domain & Equipment OOS (Note 2) tPCT =
+10 F Prior Assessments PCT PCT = 1680 F i
B. CUR. RENT LOCA MODEL ASSESSMENTS Replacement Access hole cover modification (Note 4) tPCT =
+10 F CS injection valve stroke time increased to 50 seconds (Note 5) tPCT =
+0 F Bottom Head Drain Flowpath (Note 6) tPCT =
+10 F Shroud repair including access hole cover (Note 10) tPCT =
+15 F Remove penalty for replacement access hole cover (Note 11) tPCT =
-10 F Total PCT Change from Current Assessments tPCT =
+25 F NET PCT PCT =
1705 F
Quad Cities 10CFR 50.46 Report Assessment Notes
- 1. Delav in LPCI from 48 seconds to 75 seconds after LOCA initiation On April 11,1990, an Auto-Transfer Logic Operability Surveillance, was completed during an outage on Unit 2. Part of this surveillance includes timing the transfer of Motor Control Center loads from Bus 29 to Bus 28 during a simulated loss of off-site power (LOOP) and failure of the Unit 2 Diesel Generator (DG). The transfer was timed at 38.99 seconds. The acceptance criteria for the time delay was 20 i 5 seconds. Comed had General Electric evaluate the consequences on a LOCA for this as-found relay setpoint drifL This evaluation assessed the impact of a time delay in LPCI injection due to power transfer during a LOCA and Loss Of Offsite Power (LOOP) with a Battery Failure.
General Electric practice has been to delay LPCI injection until the Recirculation Pump Discharge valve is completely closed. This valve is normally powered from bus 29. LPCI injection time is therefore the Auto-Transfer Logic time plus the Recirculation Pumn Discharge valve stroke time. The as-found relay setpoint drift would have resultedin a LPCIinjection time of 63 seconds (39 seconds for the as-found transfer time and 24 seconds for the slowest Unit 2 Recirculation Discharge Valve). Comed immediately restored the Auto-Transfer Logic to its design value of 20 seconds but conservatively retains a delayed LPCI as part ofits LOCA analysis. This was described in a thirty day 10CFR50.46 report dated March 26,1993. Quad Cities Units 1 and 2 currently maintain LPCI injection times at 75 seconds or less.
- 2. Extended Ooerating Domain / Equipment Out Of Service (EOD/EOO.S)
The report " Extended Operating Domain and Equipment Out Of Service for Quad Cities Nuclear Power Station Units 1 and 2", GE Document NEDC-31449, Revision 1, April 1992 analyzed Quad Cities for an Extended Operating Domain (EOD) allowing increased core flow above nominal values. Included as part of this analysis were the following Equipment Out-Of-Service (EOOS) and EOD operating modes: Feedwater Heaters Out-Of-Service, Single Recirculation Loo a Operation (SLO), Relief Valve Out-Of-Service, Increased Core Flow (ICF), and Fina: Feedwater Temperature Reduction. The Extended Load Line Limit region and the ICF region of the power / flow map was supported for all fuel types used. Table I below summarizes the combined modes of operation analyzed in the EOD and EOOS document for Quad Cities. Note that with the exception of the SLO condition, the EOOS analyses are valid for the Increased Core Flow Region. The conclusions of the Extended Operating Domain and Equipment Out Of Service report for Quad Cities assessed the impact on LOCA PCT as less than +10 F.
Quad Cities 10CFR 50.46 Report Assessment Notes Table 1 Equipment Out of Service Analysis and Extended Operating Domain for Quad Cities Units 1 and 2 EQUIPMENT OUT OF SERVICE APPLICABLE OPERATING DOMAIN Relief Valve-OOS EOD Including ICF Region Feed Water Heater-OOS EOD Including ICF Region Feed Water Heater -OOS and EOD Including ICF Region Relief Valve -OOS Single Recirculation Loop Operation EOD Excluding ICF Region Single Recirculation Loop Operation EOD Excluding ICF Region and Relief Valve -OOS
- 3. Reactor Vessel leakage assessed for the startup of Unit 1 Cycle 14 Emergent leakage paths associated with core shroud flaws, core spray piping flaws (repaired with the startup of Unit 1 Cycle 15) and jet pump riser flaws (repaired with the startup of Unit 1 Cycle 14) were evaluated and assigned PCT increases. For the Quad Cities Unit I restart, emergent leakage paths described above resulted in an increase in PCT of 110 F as accepted in NRC SER letter from Chandu P. Patel dated August 4, 1994. This increase resulted in a limiting PCT of 1790 *F for Unit 1 only. As a result of subsequent repairs to the Unit i Shroud and Core Spray line, the increase in PCT of 110 F from the NRC SER was later removed and replaced with separate PCT assessments associated with each repair. Note that the NRC SER 110 F PCT increase was imposed on Unit i for fuel cycle 14 only.
- 4. fleplacement access hole cover This PCT increase was applied to Quad Cities with the modification of the access covers in the core shroud support plate. These removable covers allow access from the downcomer region to the lower plenum region. This modification changed the design of the access cover from a welded design to a bolted design. The small amount ofleakage associated with the boltedjoint was analyzed and resulted in less than a 10 F PCT increase. Note that leakage from these access covers was included in each of the subsequent LOCA evaluations.
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l Quad Cities 10CFR 50.46 Report Assessment Notes
- 5. CS Injection valve maximum stroke time increased from 15 to 50 seconds Modification of the CS injection valve stroke time was necessary as a part of the NRC Generic Letter 89-10 compliance. The supporting LOCA evaluation addressed the impact l
ofincreasing the Core Spray (CS) Injection valve stroke time from a maximum of 15 l
seconds to a maximum of 50 seconds. This analysis credits the partial Core Spray flow while valves are stroking open which compensated for the longer injection valve stroke times. GE completed the analysis using their licensed SAFER /GESTR methods and determined there was no change to the LOCA PCT.
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- 6. Bottom Head Drain flowpath GE reported under 10CFR50.46 on December 15,1995 that the impact of the Reactor 1-Pressure Vessel (RPV) bottom head drain (BHD) providing an additional flow path for coolant loss under LOCA conditions was an increase less than 10 F on the PCT.
Continuous Reactor Water Cleanup system operation takes suction from the BHD and from the Recirculation suction piping which are connected at a common point. A design basis LOCA where the break is on the Recirculation suction piping would allow water in the lower plenum of the reactor vessel to be lost through the Reactor Water Cleanup piping where it connects to the Recirculation suction piping.
- 7. Remove increase in PCT of 110 F (from NRC SER reauirement. see note 3) l As a result of the rept. irs to Unit I shroud and Core Spray line, the increase in PCT of 110 F required by the NRC SER in note 3 was removed and replaced with PCT assessments associated with each repair. Note that the NRC SER 110 F PCT increase was imposed on Unit 1 for fuel cycle 14 only.
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- 8. CS Tee Box repair including CS niping leakage The purpose of the assessment was to analyze the impact ofinstalling the Core Spray (CS)
Tee Box repair clamp. This modification was necessary as a result of cracks found in the Tee Box and a subsequent commitment to the NRC to repair it. The LOCA evaluation l
was done for 4,100 GPM of CS delivered to the top of the core. The previous LOCA analysis was performed with 4500 GPM of CS delivered to the top of the core. Since the maximum CS leakage was calculated to be 277 GPM with the CS Tee box repair, this 3
represents excess leakage accounted for in the 40 F Peak Clad Temperature (PCT) penalty. This excess leakage can be used for assessment of consequences for any additional CS line flaws that may occur in the future. Note that as a result of the subsequent repairs to Unit 1 Core Spray, the increase in PCT of 110 F from the NRC SER was later removed and replaced with separate FCT assessments associated with each repair. This increase in PCT of 40 F is associated with the CS leakage including the Tee Box repair.
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Quad Cities 10CFR 50.46 Report Assessment Notes l
- 9. Jet Pump Riser repair Potential leakage paths associated withjet pump riser cracks (repaired with the startup of Unit 1 Cycle 14) were evaluated and assigned PCT increases. GE evaluated the PCT increase for two leakage scenarios which were evaluated and submitted to the NRC on July 14,1994. In that letter, the nominalleakage scenario (including the Core Spray flaw along with the repaired jet pump riser) resulted in an increase in PCT of 20 F. Note that as a result of the subsequent repairs to Unit I shroud and Core Spray, the increase in PCT of 110 F from the NRC SER was later removed and replaced with separate PCT assessments associated with each repair. This increase in PCT of 20 F is associated with the nominal leakage from the jet pump riser repair.
- 10. Shroud repair including access hole cover Repairs to the Quad Cities core shroud were completed with the startup of Unit 1 Cycle 15 and with the startup of Unit 2 Cycle 14. These repairs included installation of hardware which required machining of holes in the shroud and shroud support plate. Each of these holes have some clearance which will allow some leakage to occur at the hole's location. Also, the leakage of the cracks found in the shroud were included in the repair PCT assessment. This repair on each Unit resulted in an increase of 15 F when compared to the LOCA analysis without any shroud leakage. Included in the assessment was the replacement access hole cover leakage. Note that as a result of the repairs to Unit I shroud, the increase in PCT of i10 F from the NRC SER was removed and replaced with separate PCT assessments associated with each repair. This increase in PCT of 15 F is associated with the leakage from the shroud repair.
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- 11. Remove replacement access hole cover penalty As a result of the shroud repair assessment which included access hole cover leakage, the increase in PCT of 10 F from the modification specific assessment was removed and replaced with PCT assessment associated with shroud repair.
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