ML18198A119

North Anna, Units 1 and 2 - Attachment 5 to 18-233, ANP-3467NP, Rev. 0, North Anna Fuel-Vendor Independent Small Break LOCA Analysis Licensing Report

ML18198A119
Person / Time
Site:	North Anna
Issue date:	05/31/2018
From:	Framatome
To:	Office of Nuclear Reactor Regulation
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References
18-233 ANP-3467NP, Rev. 0
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Ser i al No. 18-2 33 LAR -SBLOCA Methodo l ogy Addit i on to COLR References Attachment 5 ANP-3467NP, Revision 0 North Anna Fuel-Vendor Independent Small Break LOCA Analysis Licensing Report (NON-Proprietary)

Virginia Electric and Power Company (Dominion Energy Virginia)

North Anna Power Station Units 1 and 2 Controlled Docu ent framat o me North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report May 201 8 Framatome Inc. (c) 2018 Framatome Inc. ANP-3467NP Revision 0 C ntrolled Docun1ent Copyright© 2018 Framatome Inc. All Rights Reserved ANP-3467NP Revision 0 Framatom e Inc. North Ann a Fuel-vendor Independent Small Break LOCA Analysis Licensing R eport Item 1 Section(s) or Page(s) All Nature of Changes Description and Justification Initial Issue ANP-3467NP Revision 0 Page i

\.JUllllU Iv' LI \,.,UII Clll Framatom e Inc. ANP-3467NP North Ann a Fuel-vendor Independent Small Break LOCA Analysis Licensing R eport Contents Rev i sion 0 Page ii Page 1.0 I N TRODUCTION

............................................................................................... 1-1 2.0

SUMMARY

OF RESULTS ................................................................................. 2-1 3.0 D E SCRIPTION OF ANALYSIS ..................................

........................................ 3-1 3.1 Description of an SBLOCA Event ........................................................... 3-1 3.2 Method of Analysis ................

.................................................

................ 3-3 3.2.1 Approved Analytical Method ........................................................ 3-3 3.2.2 Fuel-vendor Independent Appl i cation ........................................... 3-5 3.2.3 Deviat i ons from Approved Analytical Method ............................... 3-8 3.2.4 SE Compliance

............................................................................ 3-9 3.3 Plant Description and Summary of Analysis Parameters

...................... 3-10 4.0 ANALYTICAL RESULTS ................................................................................... 4-1 4.1 Break Spectrum Results ..................

....................................................... 4-1 4.2 Discussion of Limiting PCT Break Transient..

......................................... 4-2 4.3 Additional Studies ................................................................................... 4-3 4.3.1 Delayed RCP Trip ........................................................................ 4-3 4.3.2 Attached Pipe Breaks ................................................................... 4-4 4.3.3 ECCS Temperature Sensit i vity ..................................................... 4-5 5.0 R E FERENCES ......................

...........................

................................................. 5-1 The speci fi c reason(s) for claiming the information annotated herein as proprietary, as delineated in the Affidavit executed by the owner of the information, are provided as follows:

• Use of the information by a competitor would perm i t the competitor to significantly reduc e its expenditures, in time or resources, to design, produce, or market a similar produ c t or service.

• The information reveals certain distinguishing aspects of a process, methodology , or component , the exclusive use of wh i ch provides a competitive advantage for Framatome Inc. in product optimizat i on or marketabil i ty.

• The information is vital to a competitive advantage held by Framatome Inc., would be helpful to competitors to Framatome Inc., and would likely cause substantial harm to the c o mpetitive position of Framatome Inc.

Controlled Docurnent Framatome Inc. North An n a Fuel-vendor Independent Small Break LOCA Analysis Licensing Report List of Tables ANP-3467NP Revision 0 Page ii i Table 3-1 System Parameters and Initial Conditions

............................................... 3-12 Table 3-2 HHSI Flow Rates ............................................

.......................................... 3-13 Table 3-3 LHSI Flow Rates ...................................................................................... 3-14 Table 4-1 Summary of SBLOCA Break Spectrum Results ......................................... 4-6 Table 4-2 Event Times for Break Spectrum (seconds)

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4-8 Table 4-3 6.5 Inch Break -Sequence of Events ...................................................... 4-10 cu Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report List of Figures ANP-3467NP Revision 0 Page iv Figure 3-1 Generic W3 Plant Primary System Nodalization

..................................... 3-15 Figure 3-2 Generic W3 Plant Secondary System Nodalization

................................ 3-16 Figure 3-3 Generic W3 Reactor Vessel Nodalization

............................................... 3-17 Figure 3-4 Axial Power Distribution

.......................................................................... 3-18 Figure 3-5 ] ............................. 3-19 Figure 4-1 PCT vs. Break Size for Break Spectrum ................................................. 4-11 Figure 4-2 6.5 Inch Break -Cladding Temperature at PCT Node ............................ 4-12 Figure 4-3 6.5 Inch Break -Break Flow Rate .......................................................... 4-13 Figure 4-4 6.5 Inch Break-Break Void Fraction ..................................................... 4-14 Figure 4-5 6.5 Inch Break -System Pressures

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.................................... 4-15 Figure 4-6 6.5 Inch Break -Reactor Power ............................................................. 4-16 Figure 4-7 6.5 Inch Break -RCS and RV Masses ................................................... 4-17 Figure 4-8 6.5 Inch Break -Downcomer Level ........................................................ 4-18 Figure 4-9 6.5 Inch Break -Hot Assembly Collapsed Level .................................... 4-19 Figure 4-10 6.5 Inch Break -Hot Assembly Mixture Level. ...................................... 4-20 Figure 4-11 6.5 Inch Break -Cold Leg Mass Flow Rates ........................................ 4-21 Figure 4-12 6.5 Inch Break -HHSI Mass Flow Rates .............................................. 4-22 Figure 4-13 6.5 Inch Break -LHSI Mass Flow Rates ............................................... 4-23 Figure 4-14 6.5 Inch Break -Accumulator Mass Flow Rates ................................... 4-24 Figure 4-15 6.5 Inch Break -Loop Seal Upside Collapsed Levels ...................

....... 4-25 Figure 4-16 6.5 Inch Break-SG Upside Tube Collapsed Level , Broken Loop ........ 4-26 Figure 4-17 6.5 Inch Break -Secondary Mass ........................................................ 4-27 Figure 4-18 6.5 Inch Break -MFW Mass Flow Rates .............................................. 4-28 Figure 4-19 6.5 Inch Break -AFW Mass Flow Rates ............................................... 4-29 Figure 4-20 6.5 Inch Break -MSSV Mass Flow Rates ............................................ 4-30 Figure 4-21 ] ....................... 4-31 Figure 4-22 ] ................................................................................... 4-32 Figure 4-23 ] **************************************

• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 4-33 Figure 4-24 ] .......... 4-34 Controlled Docun1ent Framato m e Inc. North An n a Fuel-vendor Independent Small Break LOCA Analysis Licensing Report Acronym AFW BOC cwo CFR DC ECCS EOG EM EOC FVI HHSI LHGR LSC LHSI LOCA LOOP MFW MLO MSSV NRC RCP RCS RV PCT PWR PZR SBLOCA SE SG SI SIAS TT w W3 Nomenclature Definition Auxiliary Feedwater Beginning-of-Cycle Core W i de Oxidation Code of Federal Regulations Down comer Emergency Core Cooling System Emergency Diesel Generator Evaluation Model End-of-Cycle Fuel Vendor Independent High Head Safety Injection Linear Heat Generation Rate Loop Seal Clearing Low Head Safety Injection Loss of Coolant Accident Loss of Offsite Power Main Feedwater Maximum Local Oxidation Main Steam Safety Valve Nuclear Regulatory Commission Reactor Coolant Pump Reactor Coolant System Reactor Vessel Peak Cladding Temperature Pressurized Water Reactor Pressurizer Small Break Loss of Coolant Accident Safety Evaluation Steam Generator Safety Injection Safety Injection Actuation Signal Turbine Trip Westinghouse Westinghouse 3-loop plant ANP-3467NP Revision 0 Page v Controlled Docurnent Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report

1.0 INTRODUCTION

ANP-3467NP Revision 0 Page 1-1 This report summarizes the fuel-vendor independent small break loss-of-coolant accident (SBLOCA) analysis for North Anna Units 1 and 2. The purpose of the analysis is to provide the transient results which will support the demonstration of acceptable emergency co r e cooling system (ECCS) design performance against the 10 CFR 50.46 criteria.

The analysis was performed in accordance with the Nuclear Regulatory Commission (NRC)-approved S-RELAP5 methodology described in Reference 1 and as supplemented by Reference

2. This report justifies the use of the methodology for a fuel-vendor independent (FVI) SBLOCA analysis.

The ana l yzed North Anna plant is a 3-loop , Westinghouse (W)-designed pressurized water reactor (PWR) with an upflow barrel baffle configuration and 17x17 fuel assembl i es. The analysis supports operation at a core power level of 2951 MWt; an F a of 2.5 which includes uncertainties and K(z)=1; radial peaking , F t>H , of 1.65; 7% steam generator (SG) tube plugging in each SG; and a total initial core bypass of 6.5%. A complete spectrum of cold leg break sizes was considered , ranging from 1.0 inch diameter to 8.7 inch diameter.

In addition , sensitivity studies were performed to consider delayed reactor coolant pump (RCP) trip , attached piping breaks , and ECCS fluid temperature.

Controlled Document Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report 2.0

SUMMARY

OF RESULTS ANP-3467NP Revision 0 Page 2-1 The limiting Peak Clad Temperature (PCT) from the break spectrum occurs in the 6.5 inch break with a PCT of 1705°F. The maximum value from the break spectrum for the transient maximum local oxidation (MLO) is 1.18%. The transient MLO does not include t h e pre-transient oxidation which is dependent on cladding type. The maximum core-wide oxidation (CWO) is less than 0.04%. Consistent with the additional prescriptions of the evaluation model (EM) supplement in Reference 2 , a delayed RCP trip study , an attached pipe break study , and an ECCS temperature sensitivity study were performed.

The delayed RCP trip study analyzed both cold leg and hot leg break spectrums with a trip time of five minutes after the loss of hot leg subcooling. The attached pipe break study analyzed a break in both the pumped safety injection (SI) line connection and the accumulator line. The ECCS temperature study analyzed the sensitivity to temperatures different than those prescribed in the break spectrum analysis.

The conclusions of these studies support the break spectrum analysis as the licensing bas i s.

cu Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report

3.0 DESCRIPTION

OF ANALYSIS ANP-3467NP Revision 0 Page 3-1 Section 3.1 of this report provides a brief description of the postulated SBLOCA event. Section 3.2 describes the analytical methods used in the analysis.

That section contains a discussion of the application of the approved EM , the justification of the approved EM to fuel-vendor independent applications, any deviations , and compliance with the NRC's final Safety Evaluation (SE) of the EM. Section 3.3 presents a description of the analyzed North Anna plant and outlines the system parameters used in the SBLOCA analysis.

3.1 Description of an SBLOCA Event The postulated SBLOCA is defined as a break in the Reactor Coolant System (RCS) pressure boundary for which the break area is up to approximately 10% of a cold leg pipe area. The most limiting break location is in the cold leg pipe on the discharge side of the RCP. This break location results in the largest amount of RCS inventory loss and the largest fraction of ECCS fluid ejected out through the break. This produces the greatest degree of core uncovery, the longest fuel rod heatup time , and consequently , the grea t est challenge to the 10 CFR 50.46 criteria (Reference 3). The SBLOCA event progression develops in the following distinct phases: (1) subcooled depressurization (also known as blowdown), (2) natural circulation , (3) loop seal clearing, (4) core boil-off (5) core recovery and long-term cooling. The duration of each of these phases is break size and system dependent.

Following the break , the RCS rapidly depressurizes to the saturation pressure of the hot leg fluid. During the initial depressurization phase, a reactor trip is generated on low pressurizer pressure; the turbine is tripped on the reactor trip. The assumption of loss-of-offsite-power (LOOP) concurrent with the reactor scram results in RCP trip.

CL1 Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report ANP-3467NP Revision 0 Page 3-2 In the second phase of the transient , the RCS transitions to a quasi-equilibrium condition in which the core decay heat , leak flow , steam generator heat removal , and system hydrostatic head balance combine to control the core inventory.

During this period, the RCPs are coasting down and the system drains top down with voids beginning to form at the top of the SG tubes and continuing to form in the reactor vessel upper head and at the top of the reactor vessel upper plenum region. The loop seals remain plugged during this phase , trapping vapor generated by the core in the RCS , and resulting in a low quality flow at the break. The thir d phase in the transient is characterized by loop seal clearing.

During this phase, the loop seal , which is liquid trapped in the RCP suction piping, can prevent steam from venting via the break. When a sufficient pressure difference between the reactor vessel upper head and downcomer is reached , liquid in the loop seal is displaced, clearing the loop seal, and allowing the trapped steam to be vented to the break. For a small break, the transient develops slowly , and liquid level in the RCS may drop to t h e loop seal level prior to establishing a steam vent. The core can become tempora r ily uncovered in this loop seal clearing process. Following loop seal clearing , the brea k flow transitions to primarily steam and the core recovers to approximately the cold leg e levation, as the pressure imbalances throughout the RCS are relieved. The fou rt h phase is characterized as core boil-off.

With the loop seal cleared , the venting of steam through the break causes a rapid RCS depressurization below the secondary pressure.

As boiling increases in the core , the core mixture level decreases.

The core mixture level will reach a minimum, in some cases resulting in deep core uncovery. The boil-off period of the transient ends when the core liquid level reaches this minimum. At this time, the RCS has depressurized to the point where ECCS flow into the reactor vessel matches the rate of boil-off from the core.

Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis ANP-3467NP Revision 0 Licensing R eport Page 3-3 The last phase of the transient is characterized as core recovery and long-term cooling. The core recovery period extends from the time at which the core mixture level reaches a minimum in the core boil-off phase, until all parts of the core are quenched and covered by a low quality mixture. Core recovery is provided by pumped injection and passive accumulator injection when the RCS pressure decreases below the accumulator pressure.

The SBLOCA transient progression is dependent on the size of break and is typically broken into three different break size ranges. For break sizes towards the larger end of the brea k spectrum, significant primary system inventory loss results in larger primary system depressurization and rapid accumulator injection.

For break sizes in the middle of the spectrum, the rate of inventory loss from the primary system is such that the HHSI pumps cannot preclude significant core uncovery. The primary system depressurization rate is slow , extending the time required to reach the accumulator injection pressure or to recover core liquid level on HHSI flow. This tends to maximize the heatup time of the hot rod and produce the maximum PCT and local cladding oxidation.

For very small break sizes, the primary system pressure does not reach the accumulator injection pressure; however , primary system inventory loss is not significant and typically within the means of HHSI makeup capacity such that core uncovery is minimal if not precluded.

3.2 Method of Analysis 3.2.1 Approved Analytical Method This analysis was performed in accordance with the NRG-approved S-RELAP5 methodology described in Reference 1 and as supplemented by Reference

2. This section describes the application of the approved methodology to the North Anna plant. This application of the method to a non-Framatome fuel core is described in Section 3.2.2. Deviations from the method are described in Section 3.2.3. Compliance with the SE is described in Section 3.2.4.

lled Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report ANP-3467NP Revision 0 Page 3-4 The EMF-2328 SBLOCA evaluation model for event response of the primary and secondary systems and the hot fuel rod used in this analysis is based on the use of two computer codes. The appropriate conservatisms , as prescribed by Appendix K of 10 CFR 50 (Reference 6), are incorporated. Two computer codes were used in this analysis:

1. The RODEX2-2A code (References 4 and 5) was used to determine the burnup-dependent initial fuel rod conditions for the system calculations. 2. The S-RELAP5 code was used to predict the thermal-hydraulic response of the primary and secondary sides of the reactor system and the hot rod response. Representative system nodalization figures for a Westinghouse 3-loop plant are shown in Figure 3-1 (RCS), Figure 3-2 (Secondary System), and Figure 3-3 (Reactor Vessel). As noted in Figure 3-3 , the upper plenum noding is variable. [ ]

Controlled Docurnent F r amatom e Inc. North Ann a Fuel-vendor Independent Small Break LOCA Analysis Licensing R eport 3.2.2 Fuel-vendor Independent Application ANP-3467NP Revision 0 Page 3-5 The fou n dation of the FVI-SBLOCA application is the NRC-approved SBLOCA methodology contained in EMF-2328 (Reference

1) and its supplement (Reference 2). The met h odology incorporates the appropriate conservatisms , as prescribed by Append)x K of 10 CFR 50 (Reference

6) and is applicable to Wand CE-designed plants. It is typically used to analyze Framatome fuel products.

A fuel-vendor independent application inherently must use representative fuel design and material characteristics.

[ ] for a 17 x 17 assembly , and non-fuel related plant-specific details.

Controlled D0cun1 Framatom e Inc. North Ann a Fuel-vendor Independent Small Break LOCA Analysis Licensing R eport [ progression is described in Section 3.1. [ ANP-3467NP Revision 0 Page 3-6 ] The general SBLOCA event ] Consequently, these inputs are all plant-specific.

[ ] Important system parameters and init i al conditions used in the analysis are give n in Table 3-1 , Table 3-2 and Table 3-3. [ ]

cu Framatom e Inc. North Ann a Fuel-vendor Independent Small Break LOCA Analysis Licensing R eport [ ANP-3467NP Revision 0 Page 3-7 ] The Framatome fuel product is designed so that it can be a replacement to the resident fuel and therefore is functionally very similar to other vendor fuel desi g ns. The application was reviewed in light of the current assembly design and [ ] the analysis herein is applicable to use for 17x17 fuel products with ZIRLO a nd Optimized ZIRLO cladding. Any changes in the fuel assembly design or cladding material would need to be evaluated for continued applicability of the method and analyses results.

Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report [ ANP-3467NP Revision 0 Page 3-8 ] The results of the SBLOCA analysis described herein can therefore be used to support North Anna Units 1 and 2 with a non-Framatome core. 3.2.3 Deviations from Approved Analytical Method A deviation from the modeling approach is applied to better represent the primary system mass distribution during a specific period of the SBLOCA transient:

.,..:.,, *. $ \¢,lA F r amatom e Inc. North Ann a Fuel-vendor Independent Small Break LOCA Analysis Licensin Re ort 3.2.4 SE Compliance ANP-3467NP Revision 0 Pa e 3-9 The supplemented EMF-2328 method (Reference 1 and Reference

2) contains no restrictions.

Except as indicated in Section 3.2.3 , the analysis was performed i n accordance with the approved methodology.

d c:u Framatom e Inc. North Ann a Fuel-vendor Independent Small Break LOCA Analysis Licensing Report 3.3 Plant Description and Summary of Analysis Parameters ANP-3467NP Revision 0 Page 3-10 The Nort h Anna plant is a W-designed PWR with three loops. Each loop contains a hot leg , a U-t ube SG , an RCP, and a cold leg. A pressurizer is connected to the hot leg of one of th e loops. The reactor has a core power level of 2951 MWt (including measure m ent uncertainty). The reactor vessel contains a downcomer , upper and lower plenums, and a reactor core containing 157 fuel assemblies.

The ECCS contains two centrifug a l charging/HHS!

pumps , two low head safety injection (LHSI) pumps , and three ac c umulators.

The RCS was nodalized in the S-RELAP5 model with control volumes interconnected by flow p a ths or "junctions

." The model includes three accumulators , a pressur i zer, and three SGs with both primary and secondary sides modeled. All of the loops were modeled explicitly to provide an accurate representation of the plant. A SG tube plugging level of 7% was modeled in each SG. Important system parameters and initia l condition s used in the analysis are given in Table 3-1. The heat generation rate in the S-RELAP5 reactor core model was determined from r eactor kinetics equations with actinide a nd decay heating as prescribed by 10 CFR 50 Appendix K (Reference 6). The anal y sis assumed LOOP concurrent with reactor scram , which is based on the low pressurizer pressure reactor trip and includes delays as stated in Table 3-1. The assumpti o n of LOOP results in RCP trip. The single failure cr i terion requ i red by 10 CFR 50 Appendix K (Refe r ence 6) was satisfied b y assuming the loss of one emergency diesel generator (EOG). Thus , this results in the loss of one HHSI pump , one LHSI pump and one motor-driven AFW pump. T h e initiation of the HHSI and LHSI systems were delayed by 29 seconds , following safety injection actuation system (SIAS) act i vation. Table 3-2 and Table 3-3 show the minimum ECCS flow rates with EOG failure for HHSI and LHSI, respectively.

ntrol ' (J Clt Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report ANP-3467NP Revision 0 Page 3-11 Only two SGs were credited with receiving AFW. The AFW flow rates were minimized and were delayed 60 seconds beyond the time of the AFW system initiation on low-low SG level. The input model includes the main steam lines from the SGs to the turbine control valve , as well as the inlet piping to the MSSVs. The MSSVs were set to open at their nominal setpoints plus a 3% tolerance. The axia l power shape for this analysis is shown in Figure 3-4. [ ]

Controlled Docurnent Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report ANP-3467NP Revision 0 Page 3-12 Table 3-1 System Parameters and Initial Conditions Parameter Reactor Power , MWt Axial Power Shape Peak LHGR , kW/ft Total Peaking Factor , Fa Radial Peaking Factor , F 6 H RCS Flow Rate, gpm Pressurizer Pressure , psia RCS Average Temperature , °F Accumulator Pressure , psia Accumulator Fluid Temperature , °F Accumulator Water Volume, ft 3 SG Tube Plugging Level per SG , % SG Secondary Pressure , psia MSSV Lift Pressure and Tolerance MFW Temperature , °F AFW Flow Rate per fed SG , gpm AFW Temperature , °F Pressurizer Pressure -Low Reactor Trip Setpoint (RPS), psia Reactor Trip Delay Time on Low Pressurizer Pressure 2 , sec Reactor Scram Delay Time , sec SIAS Activation Pressurizer Pressure Setpoint , psia HHSI and LHSI Pump Delay Time on SIAS , sec HHSI and LHSI Fluid Temperature, °F Low-Low SG Level Setpoint, % Narrow Range Span AFW Delay , sec 1 Includes associated measurement uncertainty 2 Includes scram delay Analysis Value 2951 1 Figure 3-4 14.8 2.5 1.65 1 278 , 400 2250 590.7 590.4 105 968.5 7 847 Nominal + 3% tolerance 449 133.3 100 1845 2.0 0.0 1714.7 29.0 72.0 0.0 60.0 Co Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report Table 3-2 HHSI Flow Rates Pressure (psia) Intact Flow (lbm/sec) 0.0 22.0 14.7 22.0 64.7 21.8 114.7 21.6 264.7 20.8 514.7 19.4 764.7 18.0 1014.7 16.6 1264.7 15.2 1514.7 13.6 1764.7 11.8 2014.7 9.9 2114.7 8.9 2114.8 0.0 \ ANP-3467NP Revision 0 Page 3-13 Broken Flow (lbm/sec) 23.8 23.8 23.6 23.3 22.1 20.7 19.2 18.1 16.6 14.8 12.9 10.9 9.8 0.0 C Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report Table 3-3 LHSI Flow Rates Pressure (psia) Intact Flow (lbm/sec) 0.0 153.1 14.7 153.1 24.7 143.5 34.7 133.6 44.7 123.4 54.7 112.8 64.7 101.9 74.7 89.8 84.7 77.6 94.7 64.7 104.7 50.8 114.7 35.5 124.7 18.6 134.7 0.0 ANP-3467NP Revision 0 Page 3-14 Broken Flow (lbm/sec) 153.1 153.1 143.5 133.6 123.4 112.8 101.9 89.8 77.6 64.7 50.8 35.5 18.6 0.0 _J Controlled Docun1ent Framatom e Inc. North Ann a Fuel-vendor Independent Small Break LOCA Analysis Licensing Report Figure 3-1 Generic W3 Plant Primary System Nodalization ANP-3467NP Revision 0 Page 3-15 cu Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report ANP-3467NP Revision 0 Page 3-16 Figure 3-2 Generic W3 Plant Secondary System Nodalization ro-._t ' !led Docu Framatom e Inc. North Ann a Fuel-vendor Independent Small Break LOCA Analysis Licensing R eport Figure 3-3 Generic W3 Reactor Vessel Nodalization ANP-3467NP Revision 0 Page 3-17 Controlled Document Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report Figure 3-4 Axial Power Distribution ANP-3467NP Revision 0 Page 3-18 Framatom e Inc. North Ann a Fuel-vendor Independent Small Break LOCA Analysis Licensing R eport Figure 3-5 [ nt ANP-3467NP Revision 0 Page 3-19 ]

CL! Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report 4.0 ANALYTICAL RES UL TS 4.1 Break Spectrum Results ANP-3467NP Revision 0 Page 4-1 The Nort h Anna break spectrum analysis for SBLOCA includes breaks of varying diameter up to 10% of the flow area for the cold leg. The break spectrum resolution follows that prescribed by the methodology and is refined to determine the limiting break size, identified as the case with the highest PCT , and the l argest break size which depress u rizes to a pressure just above the accumulator pressure. Figure 4-1 displays the PCT results as a function of break size. A summary of the results from each case of the break spectrum analysis is presented in Table 4-1. The event times for each case of the break spectrum are provided in Table 4-2. The limiting PCT case was determined to be the 6.5 inch break with a PCT of 1705°F. This case also resulted in the limiting transient MLO with a value of 1.18%. The la r gest break size which was resolved just above the accumulator setpoint is the 2.3 inch break.

C Framatom e Inc. North Ann a Fuel-vendor Independent Small Break LOCA Analysis Licensin Re ort 4.2 Discussion of Limiting PCT Break Transient ANP-3467NP Revision 0 Pa e 4-2 The limi ti ng break from the break spectrum was determined to be the 6.5 inch break with a PCT of 1705°F. The transient progression is shown in Figure 4-2 through Figure 4-20. T h e cladding temperature at the PCT location is shown in Figure 4-2. The sequenc e of events is shown in Table 4-3. The break opens at 0.0 seconds. The break size is relatively large and the fast depressurization (Figure 4-5) results in the low pressuri z er setpoint being reached at 0.4 seconds. After the 2-second delay , the reactor trips (Figure 4-6) and , assumed coincident , the RCPs and turbine trip. The pressure in the secondary side begins to rise and is relieved via the MSSV (Figure 4-20). T h e low RCS pressure initiates the SI actuation signal at 8.1 seconds. Following the ECCS startup delays, the HHSI begins to inject at 38 seconds (Figure 4-12).

d Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing R eport ANP-3467NP Rev i sion 0 Page 4-3 The core begins to uncover at 64 seconds (Figure 4-9, Figure 4-10) and reaches the bottom at 105 seconds. At this time though there is still a significant holdup of liquid in the SG tubes (Figure 4-16). The three loop seals clear around 130 seconds. Along with the continued draining of the SG tubes, a temporary increase in the core level occurs , but the mixture level remains low with poor cooling in the upper regions (Figure 4-9 , Figure 4-10) and the clad temperature excursion proceeds (Figure 4-2). The accumulators inject at 228 seconds (Figure 4-14). There is a time delay from the accumulator injection to the mixture level reaching sufficient levels to cool the upper locations in the core and as such , the hot rod ruptures at 240 seconds. The rupture allows for interior metal-water reaction thereby increasing the local oxidation at the rupture node. The cladding temperature excursion is terminated at 241 seconds with a PCT of 1705°F. The core is initially quenched at approximately 266 seconds. The pressure continues to fall and the accumulator injects again at 320 seconds. The pressure reduces such that the LHSI shutoff head is just reached and momentarily injects a t 340 seconds (Figure 4-13), but this momentary injection of LHSI is not important in mitigation of the transient.

The core is fully quenched around 344 seconds. 4.3 Additional Studies 4.3.1 Delayed RCP Trip The break spectrum analysis assume RCP trip coincident with reactor trip. For plants such as North Anna that do not have an automatic RCP trip , a delayed RCP trip can potentially result in a more limiting condition than tripping the RCPs at reactor trip. Continued operation of the RCPs can result in earlier loop seal clearing with associated two-phase flow out the break , which would result in less inventory loss out the break early in the transient , but in the longer term could result in more overall inventory loss out the break. It has been postulated that tripping the pumps when the minimum RCS inventory occurs could cause a collapse of voids in the core , thus depressing the core level and provoking a deeper core uncovery, and a potentially higher PCT.

ment Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report ANP-3467NP Revision 0 Page 4-4 Section 1 1.K.3.5 of NUREG-0737 (Reference

7) calls for the analysis of a delayed RCP trip for SBLOCA analyses. This was followed with specific recommendations for manual RCP trip in References 8 and 9 as NRC Generic Letters applicable to Westinghouse and CE plants. Based on indications/condit i ons consistent with the North Anna licensing basis and Emergency Operating Procedures , a spectrum of hot and cold leg breaks is analyzed to support the North Anna RCP trip procedu r e. The assumed manual trip time in the analys i s is five minutes after the loss of hot leg subcooling margin. The studies demonstrated that the PCTs are over 150°F less in the delayed RCP , cold leg break study and 400°F less in the delayed RCP , hot leg break study than limiting PCT in the break analysis. In conclusion , the severity of RCP trip delayed until 5 minutes after the loss of hot leg subcooling , with a break in either location , is less than that of the break spectrum analysis with RCP tr i p coincident with the reactor trip. 4.3.2 Attached Pipe Breaks The ECCS must cope with ruptures of the main RCS piping and breaks in attached piping. To accomplish this , an evaluation is made of the ruptures in attached piping that also compromise the ability to inject emergency coolant into the RCS. When combined with a single failure , the ECCS capability is significantly compromised. The s i ze of the rupture and the portion of ECCS lost directly to containment are dependent on the plant design. In order to assure acc~ptable ECCS performance , the scope of analysis includes accidents of this type. The North Anna plant has a separate line for the accumulator and the pumped SI i njection connected to each cold leg. The high head and low head system share a common short length of pipe before joining to the cold leg. Both the accumulator and SI line break are analyzed. The accumulator line break resulted in a PCT of 1505°F and a transient MLO of 0.17%. The SI line break resulted in a PCT of 1008°F and transient MLO of 0.01 %. The results are less limiting than those of the break spectrum analysis.

Controlled Docun1ent Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report 4.3.3 ECCS Temperature Sensitivity ANP-3467NP Revision 0 Page 4-5 C ntrolled Framatom e Inc. North Ann a Fuel-vendor Independent Small Break LOCA Analysis Licensing Report Table 4-1 Summary of SBLOCA Break Spectrum Results ANP-3467NP Revision 0 Page 4-6 C cu Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Licensing Report ANP-3467NP Revision 0 Page 4-7 Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Controlled Document Table 4-2 Event Times for Break Spectrum 5 (seconds)

ANP-3467NP Revision 0 Page 4-8 Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis on ANP-3467NP Revision 0 Page 4-9 Controlled Docurnent Framatom e Inc. North Ann a Fuel-vendor Independent Small Bre a k LOCA Analysis Table 4-3 6.5 Inch Break -Sequence of Events Event Time (sec) Break Opening 0.0 Low PZR Pressure Trip 0.4 Reactor Scram , RCP and Turbine Trip 2.4 SIAS Issued 8.1 HHSI Flow: Loop 1/2/3 , Broken 38/38/38 Core Uncovery 64 AFW: SG 1 /2/3 701-/70 Loop Seal Clearing: Loop 3 , Broken 131 Loop Seal Clearing:

Loop 2 132 Loop Seal Clearing: Loop 1 132 Break Uncovery 134 Accumulator Flow: Loop 1 /2/3 , Broken 228/228/228 Hot Rod Rupture Time 240 PCT Time 241 LHSI Flow: Loop 1/2/3 , Broken 340/340/340 Approximate Core Quench 344 ANP-3467NP Revision 0 Page 4-10 Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Figure 4-1 PCT vs. Break Size for Break Spectrum ANP-3467NP Revision 0 Page 4-11 Framatom e Inc. North Ann a Fuel-vendor Independent Small Break LOCA Analysis 1 1 ed Drici, i L. V ,',.. ANP-3467NP Revision 0 Page 4-12 Figure 4-2 6.5 Inch Break -Cladding Temperature at PCT Node Cladding Temperature 2000.0 r------------------,-------,------~

G:' ::, 1500.0 1 0 00.0 "' a. E 5 00.0 -HR201-44@

10.875 ft Time(s}

Controlled Docun1ent Framatom e Inc. North Ann a F u e l-vendor I ndependent Small Bre a k LOCA Analys i s Figure 4-3 6.5 Inch Break -Break Flow Rate Break Flow ANP-3467NP Revision 0 Page 4-13 5000.0 ~~--~-~~--~-~~--~--~--~--~--~-

4 0 00.0 :? 3000.0 ., iii 0:: u:: 2000.0 :::;; 1000.0 -a Break Flow 0.0 -------------------------------~

0 200 400 600 800 1000 Time(s)

Controlled Document Framatome Inc. North Ann a Fuel-vendor Independent Small Break LOCA Analys i s Figure 4-4 6.5 Inch Break -Break Void Fraction C: 0 u E u. "O g 1.0 0.8 0.6 0.4 0.2 0.0 { 0 Br eak Vapor Void Fracti on --------Void Fra ctio n 200 400 600 800 Time (s) ANP-3467NP Revision 0 Page 4-14 1000 Controlled Docurnent Framatom e I nc. North Ann a Fue l-vendor In dependen t Small Bre a k LOCA Ana l ys i s 25 0 0.0 22 5 0.0 20 0 0.0 17 5 0.0 .. 15 0 0.0 *.; .e, ::, 12 5 0.0 "' "' a.. 10 0 0.0 750.0 50 0.0 25 0.0 0.0 0 Figure 4-5 6.5 Inch Break -System Pressures Syste m P ressures 200 400 600 Time(s) --a PZR

• SG 1 A SG 2 ~SG3 800 ANP-346 7 NP Revis i o n 0 Page 4-1 5 1000 Controlled Docu n1ent Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Figure 4-6 6.5 Inch Break -Reactor Power Re actor P ower ANP-3467NP Revision 0 Page 4-16 30 0 0.0 ~------------------------------, 2000.0 ----<11 R eac t o r P o wer 1 0 0 0.0 0.0 0 200 4 00 600 800 1000 T i m e(s)

Controlled Document Framatom e Inc. North Anna Fuel-vendor Independent Small Brea k LOCA Analysis Figure 4-7 6.5 Inch Break -RCS and RV Masses Mass ANP-3467NP Revision 0 Page 4-17 40000 0.0 ~----------------------------~

30000 0.0 ;} ';' 200000.0 "' .. :::. 100000.0 -RCS ............. RV 0.0 '--~~~~-----~-~~-----~~~~---'-~~-~---'-~~-~---'

0 200 400 600 800 1000 Time (s)

Controlled Docurnent Framatome Inc. North Anna Fuel-vendor Independent Small Brea k LOCA Analysis Figure 4-8 6.5 Inch Break -Downcomer Level Downcomer Level ANP-3467NP Revision 0 Page 4-18 30.0 ----------

---

-20.0 s .5 "O *5 O" :.:::; al "' Q. .!l! 0 u 10.0 DC L evel -Average 0.0 '--~--~-----~--~-----~--~---'-~--~---'-~--~---'

0 200 400 600 800 1000 Time(s)

Controlled D0cun1ent Framatome Inc. North Anna Fuel-vendor Independent Small Brea k LOCA Analysis Figure 4-9 6.5 Inch Break -Hot Assembly Collapsed Level Hot Asse mbly Collap se d L e vel ANP-3467NP Revision 0 Page 4-19 1 5.0 ~~--~--~--~--~--~--~--------~--, g ] Q) ....I .,, *5 CT ::J V) a. .!l! 0 1 0.0 u 5.0 --11 Liqu i d L evel a 200 40 0 soo s o o 1 ooo Time (s)

Controlled Docun1ent Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Figure 4-10 6.5 Inch Break -Hot Assembly Mixture Level Hot Assembly Mixture Level 10.0 Mixture L e v el 5.0 ANP-3467NP Revision 0 Page 4-20 0.0 .__ __ ....._._.___,___.__

____ ,__ _____ ,__ _____ .__ ____ 0 2 00 400 600 800 1000 Time (s)

Controlled Docurnent Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analys i s Figure 4-11 6.5 Inch Break -Cold Leg Mass Flow Rates RCS Lo op Flow Rates ANP-3467NP Revision 0 Page 4-21 15000.0 ------------------------------

10000.0 5000.0 \ \\ 0.0 ~~-**+***'.&"'---a* ........... *-****-****+*-**-*,&.*

• ** ** +* ..* ***W***-*+-** Loop 1 ............. Loop 2 .. Loop 3 S),-...... "' * *--** -** *--5000.0 ~--~--~--~--~--~--------------

0 200 400 600 800 1000 Ti me (s)

Controlled Docu n1ent Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Figure 4-12 6.5 Inch Break -HHSI Mass Flow Rates HHS I Mass Flo w Rates ANP-3467NP Revision 0 Page 4-22 3 0.0 ~----------------------------~

U) -. g l1J c:,: 0 u:: ., ., l1J :::!: 20.0 10.0 ."*~ **, *.*..... ,* .* *9/. *****>&************************

<<***** ... .. 1~-... -.........

--****--*---+--***************** ****************

• • • • • • • -------***********

• • ********** -----******* ------**---. / / . _,.¥ . / /' Loop 1 --+Loop2 "'Loop 3 0.0 ......... ----------------------------~

0 200 400 600 800 1000 Time (s)

Controlled Document Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analys i s Figure 4-13 6.5 Inch Break -LHSI Mass Flow Rates LHSI Mass Flow Rates ANP-3467NP Revision 0 Page 4-23 8 0.0 ~----------------------------~

60.0 20.0 0.0 ..... 0 l , 1 ,\ Loop 1 **-********* Loop 2 Loop 3 ***** Ai;*** *'-* *** If *-***i*c*' ........... , *..*.. ~,.,. ...... l. -+ .. , **** '*** ... ... .. ************+ ......... ,. 9:1: .. ..... .. I *. *, +* 200 400 600 800 Time(s) . ........... , ,.A,;*****" 1000 Controlled Docurnent F r amatome Inc. North Anna Fue l-vendor I ndependen t Small Break LOCA Analys i s ANP-3467NP Revision 0 Page 4-24 Figure 4-14 6.5 Inch Break-Accumulator Mass Flow Rates ., e .0 -:; {l a:: 0 u: "' "' "' :::E Accum ul a to r In jection 2000.0 ~-----------------------------

150 0.0 1000.0 500.0 0.0 ... .. : -500.0 l L i /\ I. ; I! i \ . ;; , ,.. __ ....... -* *-** . u * "' . L o op 1 L o op 2

• L oo p 3 ... -... ** -... -1000.0 '-------'-------'-------'----~--~--------~--~----'

0 20 0 400 60 0 800 1 0 0 0 Ti m e(s)

Framatome Inc. Controlled Document ANP-3467NP Revision 0 North Anna Fuel-vendor Independent Small Break LOCA Analysis

• Page 4-25 g .; > Cl) ...J ,, *5 er ::::; ,, Cl) .. a. .!!1 0 u Figure 4-15 6.5 Inch Break-Loop Seal Upside Collapsed Levels \r"'1 10.0 . I , I 5.0 o.o~~--= 0 Loop Seal Upside Collapsed Liquid Level Loop 1 Loop 2

• Loop 3 ........ , .. __.. ......... _ ....... l. * , .... ******** .... . **:IL:** ... *** ........ .. .. . J ** ...... ,. *** .......... *****'*** ... . 200 400 600 800 1000 Time(s)

Controlled Docurnent Framatome Inc. ANP-3467NP Revision 0 North Anna Fuel-vendor Independent Small Break LOCA Analysis Figure 4-16 6.5 Inch Break -SG Upside Tube Collapsed Level, Broken Loop g .; > ., ...J "O 30.0 J 20.0 ...J "O a. 0 (.) 10.0 Upside Tube Collapsed Liquid Level SG 1 Up side Tubes **-* SG 2 Up side Tubes --. ._ SG 3 Up side Tubes 0.0 '-----~-~~-~,&;

-**-. ****'ll**+** .... ..0.,1:. *, c-c+e,¢/~~~......,..._.--...,.

11: _ .. ..,._. I* **'*+* ***" a ..... *~+-*** Page 4-26 0 200 400 600 800 1 000 Time (s)

Controlled Docun1ent Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analys i s Figure 4-17 6.5 Inch Break -Secondary Mass S G Total M ass ANP-3467NP Revision 0 Page 4-27 180000.0 .----------------------------,.-----------, -------SG 1 ---------* SG 2

• SG 3 160000.0 -;} ; 1 4 0000.0 "' ::; Time(s)

Framatome Inc. Controlled D0cun1ent ANP-3467NP Revision 0 North Anna Fue l-vendor Independent Small Break LOCA Analys i s Page 4-28 Figure 4-18 6.5 Inch Break -MFW Mass Flow Rates SG M FW Flo w Rates 1 000.0 SG 1

• SG 2 U) & SG 3 -. .0 v .. 0:: 3: 0 u:: ::l .. ::;; 500.0 0.0 **********

-)&*******' ***********

• -*****$}*,.*** ********************£: ....... J. *******"'******

i&****'****** **** *********>Ii*********** .......... , *********** ....... .l ..*.... &***** ..... , ...* **** ... ;&*+***** 0 200 400 600 800 1000 Time (s)

Controlled Document Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis ANP-3467NP Revision 0 Page 4-29 Figure 4-19 6.5 Inch Break -AFW Mass Flow Rates 15.0 '" iii a:: 10.0 0 u:: ::l .. ::!: 5.0 . .. a A A uxi l iary F ee dw a t er Flo w . .. . .. . ... ---11 SG 1 ---.SG2 .. SG 3 0.0 ........... , .... ;. ..........

......... , .............

1.... . ...................... , ......... .J .......................... , **********************

1 ********** 0 200 4 00 600 Time (s) .. ... . .. ...............

J. .......... , ............ , ..........

............ . 800 1000 Controlled Docurnent Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analys is 1 00_0 :; .0 "" Cl:: U:: ., ., C1I ::;; 50_0 Figure 4-20 6.5 Inch Break -MSSV Mass Flow Rates MSSV Flow SG 1 Total -*---------

• SG 2 Total ----~ SG 3 Total ANP-3467NP Revision 0 Page 4-30 o.o .. -~ 0 ... * ....... :,&., ...................... :<< ........ ,. *** ., ......*.... , .......... .... ;ik* ..... *** *********" ~-** ......... J. **....*. , ........... ** *****'*.4.:+ .. . 200 400 600 800 1 ODO Time(s}

Controlled Document Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analysis Figure 4-21 [ ANP-3467NP Revision 0 Page 4-31 ]

Controlled Document Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analys i s Figure 4-22 [ ] ANP-3467NP Revision 0 Page 4-32 Controlled Docurnent Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analys i s Figure 4-23 [ ] ANP-3467NP Revision 0 Page 4-33 J L_ Controlled Document Framatome Inc. North Anna Fuel-vendor Independent Small Break LOCA Analys i s Figure 4-24 [ ] ANP-3467NP Revision 0 Page 4-34 Controlled Docun1e,nt Framatome Inc. North Anna Fuel-vendor Independent Small Brea k LOCA Analysis

5.0 REFERENCES

ANP-3467NP Revision 0 Page 5-1 1. EMF-2328(P)(A)

Revision 0 , " PWR Small Break LOCA Evaluation Model , S-RELAP5 Based ," March 2001. 2. EMF-2328(P)(A)

Revision O; Supplement 1 (P)(A}, Revision O " PWR Small Break LOCA Evaluation Model, S-RELAP5 Based ," September 2015. 3. Code of Federal Regulations , Title 10 , Part 50 , Section 46 , " Acceptance Criteria For Emergency Core Cooling Systems For Light-Water Nuclear Power Reactors ," January 2010. 4. XN-NF-81-58(P)(A) Revision 2 , " Supplements 1 and 2 , RODEX2 FUEL Thermal-Mechanical Response Evaluation Model ," Exxon Nuclear Company , March 1984. 5. ANF-81-58(P)(A)

Revision 2 , Supplements 3 and 4 , "RODEX2 FUEL Thermal-Mechanical Response Evaluation Model ," Advanced Nuclear Fuels Corporation, June 1990. 6. Code of Federal Regulations , Title 10 , Part 50 , Appendix K , " ECCS Evaluation Models," March 2000. 7. Office of Nuclear Reactor Regulation , NUREG-0737

" Clarification of TMI Action Plan Requirements" November 1980. 8. NRC Generic Letter 85-12 " Implementation of TMI Action Item 11.K.3.5 , 'Automatic T r ip of Reactor Coolant Pumps', (for Westinghouse NSSSs)" June 1985. 9. NRC Generic Letter 86-06 " Implementation of TMI Action Item 11.K.3.5 , 'Automatic Trip of Reactor Coolant Pumps', (for CE NSSSs , except Maine Yankee)," May 1986.