ML19310A224
| ML19310A224 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 01/31/1980 |
| From: | ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY |
| To: | |
| Shared Package | |
| ML17208A685 | List: |
| References | |
| CEN-126(F)-NP, NUDOCS 8006060315 | |
| Download: ML19310A224 (100) | |
Text
{{#Wiki_filter:. CEN-126(F)-NP CEAW METHOD of ANALYZING SEQUENTIAL CONTROL ELEMENT ASSEMBLY GROUP WITHDRAWAL EVENT for ANALOG PROTECTED SYSTEMS JANUARY,1980 E POWER SYSTEMS COMBUSTION ENGINEERING. INC.
. 1 i
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i d l LEGAL NOTICE THIS REPORT WAS PREPARED AS AN ACCOUNT OF WORK SPONSORED BY COMBUSTION ENGINEERING, INC. NEITHER COMBUSTION ENGINEERING NOR ANY PERSON ACTING ON ITS BEHALF: ; A. MAKES ANY WARRANTY OR REPRESENTATION, EXPRESS OR ! IMPLIED INCLUDING THE WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE OR MERCHANTABILITY, WITH RESPECT TO THE ACCURACY, COMPLETENESS, OR USEFULNESS OF THE INFORMATION CONTAINED IN THIS REPORT, OR THAT THE USE OF ANY INFORMATION, APPARATUS, METHOD, OR FROCESS DISCLOSED IN THIS REPORT MAY NOT INFRINGE PRIVATELY I OWNED RIGHTS;OR l B. ASSUMES ANY LIABILITIES WITH RESPECT TO THE USE OF, OR FOR DAMAGES RESULTING FROM THE USE OF, ANY INFORMATION, APPARATUS. METHOD OR PROCESS DISCLOSED IN THIS REPORT. O I l
ABSTRACT This report documents the new methods that can be used in analyzing the sequential CEA Group Withdrawal (CEAU) event for C-E's analog protected systems. The
, CEAW event is currently classified as requiring the Thermal Margin / Low Pressure (TM/LP) and the Axial Shape Index (ASI) trips to ensure that DNB and Centerline Temperature Melt (CTM) Specified Acceptable Fuel Design Limits (SAFDL's) are not exceeded. This document supports the reclassification of this event to a category where sufficient initial steady state thermal margin is build into DNB and Linear Heat Rate (LHR)
Limiting Conditions for Operations (LC0's) to ensure that DNB and CTri SAFDL's are not exceeded. The reclassification of this event is accomplished by relying on the High Power Trip (HPT) or the Variable High Power Trip (VHPT) and not the TII/LP and ASI trips to mitigate the consequences of this event. A detailed analysis has been performed to determine the initial conditions which cause the largest DNB and CTM margin degradation during the transient when only the HPT or the VHPT are credited. l l l l i O}
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TABLE OF C0lTE!iTS SECTI0t; PAGE tio.
- 1. IllTRODUCTICtt 1-1
- 2. DESCRIPTIOl1 0F TRAflSIEllT 2-1
- 3. CRITERIA 0F A!!ALYSIS 3-1 P 4. IflPUT PARAMETERS A!i0 I!iITIAL CC:lDITIO:IS 4-1
- 5. liETH00 0F AfiALYSIS 5-1 5.1 REQUIRED OVERP0h'ER MARGI;l O!! D lBR 5-1 5.2 FUEL CEllTERLIllE TEliPERATURE MELT SAFDL 5-4
- 6. RESULTS 6-1 6.1 REQUIRED OVERPOWER liARGIII 0l1 DiiBR 6-1 6.2 FUEL CENTERLIliE TE!iPERATURE MELT SAFDL 6-7
- 7. C0ftSERVATISMS IN THE ANALYTICAL METHODS 7-1 7.1 CONSERVATISMS IN CALCULATIO:1 0F REQUIRED OVER POWER 7-l MARGItt ON DriBR 7.2 CONSERVATIstiS IN CALCULATIO!4 0F FUEL CENTERLIllE TEliPERATURE 7-3 liELT SAFDL
- 8. ~C0t1CLUSI0 tis 8-1
- 9. REFEREliCES 9-l
- 10. APPE!! DIX A :-l liETHODS USED TO DETERMINE EXCCRE DETECTOR RESPONSES DURING A CEAW TRANSIENT a
LIST CF TABLES TABLE fl0. TITLE PAGE 4-1 Key Input Parameters Considered in the CEAW 4-4 Event Analysis ' 6.1-1 Required Overpo.ecr Margin at 102% of Rated Power 6-10 6.1-2 Required Overpower fiargin as a Function of ASI 6-11
.<t 102% of Rated Thermal Power 6.1 - 3 Required Overpower Margin at 70% and SO: 6-12 of Rated Thermal Power 6.1-4 Final Required overpower Hargin as a Function of ASI 6-13 it 70% of Cated Thermal Power 6.1 - 5 Sequence of Events for CEA Withdrawal Event 6-14 Initiated at 102% of Rated Power 6.1 - 6 Sequence of Events for CEA Withdrawal Event 6-15 Initiated at 70% of Rated Power 6.1 - 7 Sequence of Events for CEA Withdrawal Event 6-16 Initiated at 50% of Rated Pcwer 6.1 - 8 Sequence of Events for CEA Withdrawal Event 6-17 Initiated at HZP.
6.2-1 PLHGR as a Function of Power Level 6-18 7.1-1 Key Input Parameters Used in CEAW Event 7-5
. Initiated from 102% of Rated Power 7.l-2 Key Input Parameters Used in CEAW Event 7-6 Initiated frca 50% of Rated Power 7.1-3 Sequence of Events for CEA Uithdrawal Event 7-7 Initiated at 102% of Rated Power (Best estimate) l 7.1-4 Sequence of Events for CEA Withdrawal Event 7-8 ,
Initiated at 50" of Rated Power (Best estimate) l i l l l ? , I I l .
LIST OF FIGURES t,1 CURE fl0'. TITLE PAGE 1-1 Power Dependent Insertion Linit 4-5 5,1-1 Procedures Used to Determine DrtBR Required 5-6 Overpower Margin 5,2-1 Procedures for Calculating PLHGR 5-8 6.1-1 CEA Withdrawal Event from 102% Power - R0PM (DriBR) 6-19
.vs. CEA Reactivity Insertion Rate with Hgap Equal to 6.1 -2 ' CEA Withdrawal Event from 102% Power - ROPM (D:iBR) 6-20 ys. CEA Reactivity, Insertion Rate aith Hgap Equal to 6.1-3 CEA Withdrawal Event from 102"; Power -ROPM (DllBR) 5-21
.vs. CEA Reactivity) Insertion Rate with Hgap Equal to 6.1-4 CEA Withdrawal Event from 102% Pcwer -ROPM (Dt'SR) 6-22 ys. CEA Rcactivity, Insertion Rate with Hgap Equal to 6.1-5 6-23 CEA Withdrawal Event from 102% Power R0FM (DilBR) vs. CEA Reactivity Insertion Rate and Hgap
- 6.1-6 6-24 CEA Withdrawal Event from 102% Power R0PM (DtlBR) ys. CEA Reactivity Insertion with MTC Equal to 6.1-7 6-25 CEA Withdrawal Event from 102% Power R0PM (Df!BR)
,vs. CEA Reactiv.ity Insertien Rate with MTC Equal to 6.1-8 CEA Withdrawal Event frcm 102% Powe - Axial Shape 6-26 Index Shift vs. Initial Axial Shape Index l 6.1-9 CEA Withdrawal Event from 102% Power - Integrated Radial 6-27 Decrease vs. Initial Axial Shape Index 6.1-10 CEA Withdrawal Event from 102% Power - Penalty Factor 6-23 on 0:lBR R0Pf! vs. Initial Axial Shape Index 6.1-11 6-29 CEA Withdrawal Event' from 102) Power R0PM (DilB) vs.
Initial Axial Shape Index 6.1-12 6-30 CEA Withdrawal Event from 70% Power R0PM (0lBR) vs. CEA Reactivity Insertion Rate 9
LIST OF FIGURES (CC TI!;UED) ' FIGURE t10.- _ TITLE PAGE 6.1-13 CEA Withdrawal Event from 50" Power R0Pf1 (DiiBR) 6-31 vs. CEA Reactivity Insertion Rate 6.1-14 CEA Withdrawal Event from 705 Power Axial Shape
)
6-32 Index Shift vs. Initial A.<ial Shape Index 6.1-15 CEA Withdrawal Event from 70% Pcwer - Integrated
, 6-33 Radial Decrease vs. Initial Axial Shace Index 6.1-16 CEA Withdrawal Event frcm 70% Pcwer - Penalty 6-34 Factor on D:iBR R0P 1 vs. Initial Axial Shape Index 6.1-17 CEA Withdrawal Event from 70% Pcwer R0P!1 (DilS) 6-35 vs. Initial Axial Shape Index 6.1-18 CEA Withdrawal Event from 50% Power Axial Shape 6-36 Index Shift vs. Initial Axial Shape Index 6.1-19 CEA Uithdrawal Event from 50: Power - Integrated 6-37 Radial Decrease vs. Initial Axial Shape Index 6.1-20 CEA Withdrawal Event frem 50'; Power - Penalty 6-38 Factor on DtlBR R0rn vs. Initial Axial Shape Index 6.1-21 - CEA Withdrawal Event - Required Overpower Margin 6-39 vs. Initial Power Level 6.1-22 CEA Withdrawal Event from 102% Power - Core Power 6-40 vs. Time 6.1-23 CEA Withdrawal Event from 102% Power - Core Average 6-41 Heat Flux vs. Time 6.1-24 '
CEA Withdrawal Event from 102% Power - RCS Temperatures 6-42 vs. Time 6.1-25 CEA Withdrawal Event from 102% Power RCS 6-43 Pressure vs. Time I 6.1-26 CEA Withdrawal Event from 70% Power Core 6-44 Power vs. Time ' 6.1-27 CEA Withdrawal Event from 70% Power Core 6-45 Average Heat Flux vs. Time I 6.1-28 CEA Withdrawal Event from 70~, Power RCS Temperatures vs. Tine 6-46 6.1-29 ) CEA Withdrawal Event from 70% Power RCS 6-47 Pressure vs. Time
LIST OF FIGURES (CONTINUED) FIGURE tio. TITLE PAGE 6.1-30 CEA Withdrawal Event from 50% Power Core 6-48 Power vs. Time 6.1-31 CEA Withdrawal Event from 50% Power Core 6-49 Average Heat Flux vs. Time 6.1-32 CEA Withdrawal Event from 50% Pcwer RCS 6-50 Temperatures vs. Time 6.1-33 CEA Withdrawal Event frcm 50% Power RCS 6-51 Pressure vs. Time 6.1-34 CEA Withdrawal Event from HZP Power Core 6 Power vs. Time 6.1-35 CEA Withdrawal Event from HZP Power Core 6-53 Average Heat Flux vs. Time 6.1-36 CEA Withdrawal Event frem HZP Power RCS 6-54 Temperatures vs. Time 6.1-37 CEA Withdrawal Event from HZP Power RCS 6-55 Pressure vs. Time 6.1-38 CEA Withdrawal Event frca 102% Power Excore 6-56 Detector Pcwer vs. Time 6.1-39 CEA Withdrawal Event frca 70% Power Excore 6-57 Detector Power vs. Time 6.1-40 CEA Withdrawal Event from 50% Power Execre 6-58 Detector Power vs. Time 6.2-1 CEA Withdrawal Event frca 102% Power Peak 6-59 Linear Heat Generation Rate vs. Gap Thermal Conductivity 6.2-2 CEA Withdrawal Event from 102" Power Peak 6-60 Linear Heat Generation Rate vs. Initial Power Level 6.2-3 CEA Withdrawal Event Frcm 102% Power Core Power 6-61 vs. Time 6.2-4 CEA Withdrawal Event from 70% Power Core Power 6-62 vs. Tine 6.2-5 CEA Withdrawal Event from 50% Power Core Power 6-63 vs. Time L
LIST OF FIGURES (C0tlTI!!UED) FIGUkENO. TITLE PAGE 6.2- 6 CEA Withdrawal Event from HZP Core Power 6-64 vs. Time 7.1-1 CEA liithdrawal Event from 102% Power Core Power 7-9 vs. Time 7.1-2 CEA Withdrawal Event frca 102% Power Core 7-10 Average Heat Flux vs. Tina 7.1-3 CEA Withdrawal Event frem 102% Power RCS 7-11 Temperatures vs. Time 7.1-4 CEA Withdrawal Event frca 102% Power RCS 7-12 Pressure vs. Tine 7.1-5 CEA Withdrawal 7. vent from 50% Power Core Power 7-13 vs. Time 7.1-6 CEA liithdrawal Event from 50% Power Core Average 7-14 Heat Flux vs. Time
1
. - 7 CEA Withdrawal Event from 50% Power RCS 7-15 Temperatures vs. Tine 7.1-8 CEA Withdrawal Event from 50% Power RCS 7-16 Pressure vs. Time 7.2 CEA Withdrawal Event from 102% Pcwcr Core 7-17 Power vs. Time 7.2-2 CEA Withdrawal Event from HZP Core 7-18 Power vs. Time l
l l l l i
- LIST GF ACP.0'tYt S A!!D ABCPE'/I ATICTIS A00 Anticipated Operational Occurence (s)
AR0 All Rods Out ASI Axial Shape Index CEA Control Element Assembly
. CEAW Control Element Assenbly Withdrawal lCEAWrate CEA Reactivity Insertion (withdrawal) Rate' I
j "T!! Centerline Temperature Melt DBE Design Basis Event (s) I D!!B Departure from t'ucleate Boiling 0:tBR Departure feca ttucleate Boiling Ratio lFA Peaking Augmentation Factor i
' FP Fractional Power Rise during the Transient F
g Integrated Radial Peak I
~
- ,' FTC Fuel Temperature Coefficient
,1 F TILT Azimuthal Tilt Allowance
- F Z Axial Peak
Hggp Gap Thermal Conductivity HPT liigh Pcwer Trip HIP Hot Zero Power l
, LC0 Limiting Condition (s) for Op: ration LHR Linear 11 eat Rate I
f MTC Moderator Temperature Coefficient a MWt Megawatt (s), thermal NSSS Nuclear Steam Supply System (s)
, POIL Power Dependent Insertion Limit i
3 -
.2
LIST OF ACfCilYM'i Af!D ABBREVI AT[C'!i (CO?lTIrlUED) PLCS Pressurizer Level Control System PLHGR Peak Linear Heat Generation Rate PPCS Pressurizer Pressure Control System
. RCS Reactor Coolant System R0PM
- Required Overpower Margin RPS Reactor Protective System RSF Rod Shadowing Factor SAFDL Specified Acceptable Fuel Design Limit (s)
T Centerline Temperature q IM/LP Thermal Margin Low Pressure TSF Temperature Shadowing (Attentuation) Factor VHPT Variable High Power Trip AE Integrated Energy Rise AE q Centerline Energy Rise LE Integrated Energy Risc at Hot Spot g ,3, 4FN 9 Fractional Increase in 3-D Peak Fxy Planar Radial Peak l l l l l l l i I
- l. INTRODUCTION The purpose of this report is to document the new nethods ubich can be used in analyzing the Control Eler:ent Assembly Group With-drawel (CEA;I) event. The methods reported herein are applicable to florida Poucr and Light, St. Lucie Unit I.
for Anticipated Operation 61 Occurrences (A00's) the DNB and Centerline Tereperature Melt (CTM) Specified Accepteble Fuel Design Limits (SAFDL's) will not be violated provided:
- 1. The actuation of a Reactor Protective System (RPS) trip intervenes to ensure that SAFDL's are not exceeded, cr
- 2. 9;fficient initial margin is built in to ride through the transient without requiring a trip, or there is an RPS trip in combination with sufficient initial steady state margin to the DN3 and CTM SAFDL's. This initial margin is provided by Limiting Conditions for Operations (LCO's) specified in the plant Technical Specifications.
As stated in CENpD-199-P (Reference 1), the CEAW event has teen ; classified as an A00 requiring the actuation of an RPS trip. Specifically, the Thermal Margin / Lou Pressure Trip prevents exceeding the DHS SAFDL and the Axial Shape Index (ASI) trip prevents exceeding the CTM SAfDL. Thus, in the past this event was analyzed to calculate the pressure bias input to the Tit /Lp trip to ensure that DMC SAFDL uas not exceeded and to confirm that power input to both the T!!/Lp and axial shape index trips was conservative. 1-1
- e or The pressure bias term accounted for the margin degradation frca the time a TM/LP trip signal is actuated to the time of transient '
minimum Oti,SR. The bias term accounts for temperature and pressure differences between the actual system temperatures and pressures at thn time a trip setpoint is encountered and those at the time of minimum OllBR. The pressure bias factor along with conservative power, temperature and pressure input to the TM/LP trip ensured that DliB SAFDL would not to exceeded. The CTM SAFDL would not be exceeded due to the actuation of the ASI trip utili;:ing conservatively high power input signals. The new method and its consaquences, which are described in detail in this document, justify reclassification of this event from the category requiring the action of TM/LP and ASI trips to the category where sufficient ini;ial steady state thermal margin is built into the C:!B and LHR LC0's to ensure that SAFDL's are not exceeded. Credit is taken only for the High Power Trip (HPT) and the Variable High Power Trip (VHPT). The new method is based on calculating the Required Overpower Margin (ROP!i)
' that must be provided by adherence to the LCO's. Actuation of the HPT or the VHPT is then sufficient to prevent violation of SAFDL's in lieu of including a pressure bias component in the TM/LP trip algorithm.
It should be noted that the bias term for the TM/LP is still determined for other transients as described in Reference 1. l In summary, this document describes and justifies the following: i l
- 1. The new methods and procedures used to calculate the 0?iB and LHR R0Pri's.
I
- 2. The results of the detailed analysis, including sensitivity studies for Ley parameters, which establish conservative l estimates of DilB and CTl1 margin degradation.
i 1-2
- 2. DESCRIPTIOll OF TRAriSIEiT To understand what the key parameters are, a b-ief description of the transient follows:
A CEA withdrawal event is assumed to occur as a result of a failure in either the Control Element Drive Mechanism Control System (CECMCS) or the Reactor Regulating Systen (RRS). The withdrawal of CEA's inserts positive reactivity which increases the core power and heat flux. The increasts in the core power and heat flux in turn increase the Reactor Ccolant System (RCS) temperatures and pressure. The withdrawal of CEA's can also shift the axial power distribution tcward the top of the core. Also, as the CEA are withdrawn, the integrated radial peaks (Fq ) decrease. The withdrawal of CEA's generally decalibrates the flux power signal measured by the excore detectors. These detectors provide power input to the RPS. However, the magnitude of the decalibration due
'to CEA motion is offset by the decreased neutrcn flux attentuation (temperature shadawing) due to increases in the inlet coolant temperature. A discussion of the excore detector respenses during a CEAU event is given in the Appendix.
The calculation of margin degradation during this event accounts for the following:
- 1. increases in core power
- 2. increases in core heat flux
- 3. increases in RCS temperatures
- 4. increases in RCS pressure
- 5. decreases in core mass ficw rate (due to density changes)
- 6. changes in axial power distribution and integrated radial peaks.
u
Since the overall margin degradation during this event depends on the combined effects of changes in all of the above mentioned parame'ters, a detailed sensitivity study on key parameters was performed to establish a ccabination of parameters which produces maximum margin degradation. 2-2 .
- 3. CRITERIA CF A'fALYSIS The CEAU event is classified as an A0G hence the following criteria are applicable.
1J liinimum Transient DN3R > DNBR SAFDL based on CE-1 correlation (I} ii) Maxicun Fuel Centerline Temperature at Melt (2) < 5080 F - 210 X Burnuo (M'.!D/MT) 50,000 (MWD /MT)
!!0TES: 1. CZ-1 DNBR shall have a minimum allcwable limit corresponding to a 95% probability at a 95% confider.ce level that DNS will not occur. In this study a DNSR of 1.19 was used.
- 2. The fuel centerline melt SAFDL is not exceeded if the Peak Linear Heat Generation Rate (PLHGR) does not exceed a steady state limit. In this study a limit of 21 KW/ft was used.
for some CEA'I caser, the reactor power rises rapidly for a
~
very short period of time before the power transient is terninated. Hence, for these CEAW cases where the steady state limit of 21 KW/ft is exceeded, the total energy generated and the corresponding temperature rise at the hot spot are calculated for the duration of transient to deioonstrate that fuel centerline temperatures do not exceed U0 melt temperatures. That is, for rapid power spikes of 7 short duration a time at power is core significant than the peak linear heat generation rate achieved. l l 1 3-1 ',
- 4. IMPil? PARAMETERS AND INIT!?L CONDITIONS Table 4-1 presents the ranga of initial conditions considered in this analysis. The reactor s 's parameters of primary importance in calculating the margin degradation are: 1) CEA withdrawal rate" (i.e.,
reactivity inserti i te), 2) gap thermal conductivity (Hgap)'
- 3) initial power level, 4) flux pcwer Icvel determined from excore detector response during the trans.ient, 5) the 14oderator Temperature Coefficient (l4TC) of reactivity, and 6) axial power distribution and planar and integrated radial peaking factor changes durir.; the transient.
A parametric analysis in Hgap, CEA withdrawal (or reactivity insertion) rate and the MTC was performed to determine the ccmbination of these parameters which produces the largest margin degradation during
.the event. The analysis was performed at various power levels to obtain the nargin degradation during the transient as a fur.ction of initial power level. The excore detector responses for each initial power level analyzed were based on the CEA insertions allowed by the Power Dependent Insertion Limit (pDIL) (See Figure 4-1) at .
the selected pcwer level, the changes in CEA position prior to trip, and the corresponding rod shadewing and temperature attentuation (shadowing) factors. The methods used to determine the excore I detector responses during the transient are presented in the Appendix. l Other input parameters of importance are the Fue' ~ perature Coefficient ! (FTC) of reactivity and the initial and final , power distributions. A FTC corresponding to beginning of life conditions was used in the analysis, since this FTC causes the . east amount of negative
- Note: The term CCA withdrawal rate and CEA reactivity insertion rate are used interchangeably in this. report.
l ' i 4-1
reactivity feedback to offset the transient increases in core pcher and heat flux. TheuncertaintyontheFTCusedintheanaiysesis shown in Table 4.1 and is the same as quoted in previous reload licensing submittals. For the CEAU cases where the ccmbinations of parameters result in a reactor trip, the scram reactivity versus insertion characteristics assumed were those associated with a core average axial power i distributicn peaked at the bottom of the core. The bottcm peaked shape assumed is characterized by a shape index cf [ ]. The scran reactivity versus insertion characteristics associated with this bottom peaked shape minimize the amount of negative reactivity inserted during the initial portion of the scram following a reactor trip. This, in turn, maximizes the time required to turn around the transient power, heat flux and coolant temperature increases. Ilowever, it should be noted that a botten peaked shape is used only to determine the NSSS response during the event. These responses were then combined with the axial power distributions shifted toward the top of the core. Initial axial power distributions allowed within the positive and negative shape index extrenes of the DNS LCO band were evaluated to obtain the margin degradation as a function of shape index. All control systems except the Pressurizer Pressure Control System (PPCS) and Pressurizer Level Control System (PLCS) were assumed to be in manual mode. These are the most adverse operating modes for this event. The PPCS and PLCS were assumed to be in the automatic mode since the actuation of these systems minimizes the rise in the coolant system pressure. The net effect is to delay a reactor trip until a liigh Power trip is initiated. This allows the transient increases in power, heat flux and coolant temperature to prnceed for a longer period of time. ' A3
In addition, minimizing the pressure increase is conservative in the margin degradation calcult.fons since increases in pressure would offset some of the CNB margin degradation caused by the increases in the core heat flux and the coolant temperatures. 4-3 * [ .
TACI.E 4-1 KEY I !PUT P/,PA!ETERS
..n:P.EPE3 1:1 THE CE?.: E!E::7 li::ALY315 Parameters Range of Units Values Initial Power Level % o f 27i 0 i.!t 0 to 102 Initial Ccolant Temperature 'F 532 to 550*
Initial Coolent Systen Pressure psia 2200+ Iritial Core itass Velocity 6 2 x10 l bm./hr-f t 2.53+ floderator Tenperature Coefficient ~4 X10 ap/'F +.5 tc -2.5 Fuel Temperature Coefficient Uncertainty i' -15,0+ Gap Thermal Conductivity BTU /hr-ft 2
'F [i ;)
Axial Shape Index for Scram asiv [, y Characteristics CEA liif ferential North X10'?' Lp/ inch [- ] CEA Withdra.al Speed inches / minute 30.0 i CEA '.l orth at Trip: 1003 % t.p > -4.6+ All other power levels % to {-3,4+ Hich Po cr Trip Analysis Setpoint 5; cf 2710 it.'t 112.0 Variable High Power Trip Analysis '; above initial Sctroint power level 10.0 Integrated Rcdial Peaking Facter 1.6S to 2.6** Itaxinun 2D-Peak, Fxy+ ** 2.G* i
+
l Itaxirn.n Axial Pesk, F Z
+
Auqtentation factor, F *** 1.07 A Uncertainty, F U:lC 1. O Tilt (HZP), F *** I'10 T
' Tenpereture Shadowing Factor i: Power / F [ ]
Initial T. in values used are naxinum for a oiven pcuer level .b . sed en the Tave Program. The integrated raJial pedine factors u. sed are the u ir% rnr a given oc.:er level based on th9 CFA insertians Ilc. e d h' Pnit. e t ' t level. Vil hi UsCd i n CalCul0lih6) ' 4u3 iUJl C"htf'lin" o ' f c ~. U f ? - and ninicun 0:iCR fcr CEA'.! evenc initiated 2: MZP. 4 The initial valut . of thnc parcreu r are selcc:.ed *., be 'hnic which prod >ry thc r wiu.a.; margin nr W tian. 6 - .1
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- 5. t!ETHOD OF ANALYSIS The Nuclear Steam Supply System (NSSS) response to a CEA group with-drawal event was simulated using the digital ccmputer code CESEC, described in CEMPD-107 (Reference 2 ). The thermal hydraulic design code TORC described in CEMPD-162-P (Reference 3 ) was used to calculate the thermal margin degradation during the transient.
The LHR margin degradation was calculated using the procedures and methods discussed in Section 5.2. 5.1 REr)UIRED OVERF0VER MARGIN ON DNOR The calculation procedures used in the analysis to determine DNB R0PM are presented in Figure 5.1-1. This procedure consists of: 1. Simulation of the CEAW transient usino CESEC to determine the heat flux, coolant system temperatures and the coolant system pressures during the event. The key input parameters are discussed in Section 4.
- 2. A set of TORC cases are run to determine the time of minimum DNBR. Input to TORC are the time dependent values of heat flux, Tin, pressure and core mass flow rate predicted by CESEC. Other input parameters are integrated radial peak and axial power distribution.
- 3. A TORC case is run to determine the rod average power at whic.h the fuel design limit on CNBR is reached for the 5-1 '
4-_
ini t ial s teady s ta te system parci" w... This value of power is designated B),
- 4. The imat flux, inlet temperature, pressure and core mass flow at the time of minimum D:BR deteruined in step 2 are used in conjunction with initial value of integrated radial peak and axial power distribution to obtain a power at which the fuel design limit on D::DR is reached for the transient condi tions. This power is designated B 2' *
- 5. The Required Overpower 11argin (ROPit)) (i.e., margin degradation) 0 1
is computed as; F,0 Pit) = g- :: 1003, 2
- 6. The QUIX code (Reference 4) is used to simulate a CEAU event to deterair.e the axial power distribution (AkPD)' changes and the decrease in the integrated radial peak. The input to QUIX are, 1) the transient variations in power and coolant temperatures predicted by CESEC, 2) the CEA bank worth,
- 3) CEA bank configuration-dependent rod shado' ling factors,
- 4) CEA bank configurationidependent radial peakino, factors, 5) allowed CEA configuration at the initial power level based on the PDIL, and 6) shape annealing functions. The code calculates the initial and time dependent axial pcuer distributions, radial peaking factors, ex-core indicated power, and shape index accounting for the transient variations in the xenon distributions and feed back effects. ;
i
- 7. Determine the riargin loss due to the axial po'. er shape change and the margin gain due to the decrease in the radial peak for the range of ASI allowed by the D:13 LCO band. The sum of these i
two components provides a net penalty factor, I;3, on the ROPM at each axial shape index allowed by the IMS LCO hand. The 1 penalty factor; B3 , is. calculated from tim following relationship: l 5-2
This section describes C-E proprietary methods used in the analysis of the net penalty factor, 83, on the Required Overpower .'4argin. P l
- 8. Calculate the total DNB margin degradation as a function of
, initial shape index from the relation: [ ]
- 9. For CEAW event initiated from Hot Zero Pcwer (HZP) calculate the transit.it mininum DNBR, using the maximum value of
, integrated radial peak, a conservative AXPD and the maximum l heat flux predicted by CESEC,to demonstrate that DNB SAFDL l is not exceeded. l I l 5-3 - 1 . .
\
l
5.2. FUEL CE!!TERLINE TEMPERATURE 11ELT SAFCL The procedures used to ensure that the fuel centerline melt SAFDL is not exceeded are displayed schematically in Figure 5.2-1. These procedures are as fcilows: , l. Simulate the CEAU transient with CESEC to obtain the fractional power rise during the event.
- 2. The fractions 1 power rise obtained in the previcus step is used along with equation 5.2-1 to calculate the Peak KW/ft during the event.
PLHGR = PLHGR + APLHGR = - Equation 5.2-1 7 PLHGR x (1 +FP) x (1+aFg'l) where: PLHGR
= Peak Linear Hear Generation Rate during the event PLHCR I = Initial Peak Linear Heat Generation Rate allowed by the KW/ft LCO, including all uncertainties.
APLHGR
= Change in PLHGR due to, power increases and power distribution changes, FP = Fractional Power rise during the event.
U AF q = Fractional Increase in 3-D neak during the event, 3. The maximum centerline temperatures (Tq ) are calculated for the CEAW cases which exceed the steady state limit of 21 KW/ft to-demonstrate that the UO melt temperatures are not exceeded 2 for high LHR's of short duration. The procedure to calculate t the fuel centerline temperatures (Tq ) consists of the following steps:
- a. Calculate the average integrated energy rise (AE) during i
the transient based on the power excursion predicted by CESEC. 5-4 -
- b. Calculate the energy rise at the hot spot using equation 4.2-1.
6E gg,3 = aE xF yy xF 7 x F x F x F A T UNC - Equation 4.2-1 where: LE = average energy rise AE g,3 = Energy rise at hot spot F = xy Maximum 2-D Peak durino transient F = itaxinua~Axi 1 Peak during transient Z F = A Augmentation Factor (taken to be maxitum at top of core} F = T Azimuthal Tilt Allcwance F = UNC Uncertainty (cn local peaking and power) Since no credit is taken for heat transfer out of the fuel, the energy rise at the hot spot is equal to the centerline energy rise (AEq). Hence oE = aE g,3 q
- c. Obtain the centerline temperature rise (AT ) corresponding to the centerline energy rise by integrating as a function of tennerature the specific prcperties of UO described 2
in Reference 5, assuming no heat transfer cut of the fuel. l d. Calculate maximum centerline temperature froni: u = l + T*q
- T AT where:
3 T*g * = H3ximum centerline tenperature I T = Initial centerline temperature AT = centerline temperature rise obtained in step c. q 5-5
t' . AXIAL SHAPE > < INITIAL TIN i CEAW TRANSIENT CEAW RATE = F 2 SIMULATION USING < INITIAL PRESSURE q H GAP
- CESEC E EXCORE DETECTOR > < INITIAL HEAT FLUX M
Lo RESPONSE . c TRANSIENT VARIATION - Kl IN TIN, HEAT FLUX AND 1
, y PRESSURE i y
$a FLOV1 RATE' CORE MASS w u mm u TORCTO DETERMINE F4 < -
AXIAL SHAPE = POWER TO TORC TO Y'
. "N E DETERMINE TIME OF CORE MASS FLOW RATE - -
DNBR LIMIT-FOR INITIAL m E) !$ MINIMUM DNBR STEADY STATE z o - INTEGRATED RADIAL + CONDITIONS z E8 CORE MASS FLOW RATE y HEAT FLUX, T IN AND
. .o PRESSURE AT TIME OF 5 MINIMUM DNBR M '
P TORC TO DETERMINE -
@ POWER TO DNBR '
ER .
~ LIMIT FOR TRANSIENT i CONDITIONS .,__
B2 l y, f v , 7s B1 81
~m I K_OPM y B2 a '
o
d i i 1 POVER AND COOLANT 1
' R0D SHADOWING FACTORS - CEAW TRANSIENT -
TEMPERATURES FROM CESEC . N SIMULATION USING INITIAL CEA CONFIGURATION -- _ INITIAL AXIAL POWER c QUIX DISTRIBUTION l] INITIAL INTEGRATED RADIAL - - CEA BANK WORTil
! A ;8
.( 88 AXIAL SHAPE SHIFT DECREASE
.]
$y o m IN INTEGRATED RADIAL 3 .
c i @U CALCULAlE PENALTY FACTOR ON R0PM m gc - c u g; r, @o
~m 9 go j g; -
t m w.
-s i zO PENALTY FACTOR , B
- E P6 3 u
$. E r -
) 55 -
. LO
-3 w C 1
4 ' GAP SIMULATE CEAW AE TRANSIENT USING < - CEAW RATE CESEC ,,
. AXIAL PODER DlSTRIBUT10N
, FP Y ,
PLHGR
- + I -
PLHGR "qpN I O PLHGR > A PLHGR .
. IF PLHGR EXCEEDS y STE.ADY STATE LIMIT
- . Fg F
A L AEH. S = o E x Fg x FA x FTx FUNC +-- IT F c UNC AE;;,3 = AEg l CALCULAlE l AT 0. AT f' i' - l i max I T =Tg +^Tg - , nounn l PROCEDUl ES FOR CALCULATilR: Pl.IlGR J, . 2-1
- 6. RESul.TS
- The porpose of this section is to discuss the results of the parametric analysis performed to establish limiting combinations of paraceters and to display values of the maximum OflBR and peak linear heat generation rate R0 Pit's obtained.
6.1 REQ'JIRED OVER PO'.!ER MARGIfl O'l CilBR The results of the parametric analysis in CEA reactivity insertion rate and H with a constant ?1TC of [ ] Ap/ F are presented gap in Figures 6.1-1 to 6.1-4. These figures present the results for the CEAW cases which initiated a reactor trip and the cases which did not initiate a reactor trip. The highest R0PM is obtained for (
] The RCPf1 is highest for this case because the inlet temperature is [ ] and the RCS pressure [ ] at the time of minimum DilSR than for cases which [
] .' The core power and heat flux also achieve a new [ ]
steady state value, but ,
} This occurs because of the [ ]
coolant temperatures and leads to the I J. This causes the 1 Figure 6.1-5 presents the R0 Pit for the' The results are also tabulated in Table 6.1-1 for the CEAU rates that produced the aaximun R0P'1 for each of the l l 6-1
~
l " y , _ }
Hg ,p values analy:cd. As seen frcm the Table [ 1 J A similar study in CEA',1 rate and H was performed with an MTC gap of [ ] ao/ F. Figure 6.1-6 presents the results of this parametric analysis. The results indicate that the maximum R0PM for cases with an MTC of [ ] ao/ F is lower than the R0PM's obtained frcm cases with an MTC of [ ] ap/ F. This occurs because with an liTC of [ ] ap/ F, [ 4 The larger positive reactivity insertion further accelerates the core power and cool' ant temperature rise. The faster inc ease in coolant temperatures in ccmbination with 1 This occur s even for CEAN reactivity insertion rates as low as [ ] Ap/ inch. An analysis was also performed with an MTC of [ ] ao/ F. The results presented in Figure 6.1-7 indicate that the transient is self limiting because the increase in coolant temperature in combination with the [ ] retards the power, heat flux and temperature increases. Hence, with ]thepowerrise, coolant temperature rise and heat flux increase are much smaller than with , Thus, the margin degradaticn is also lower for mare The net result of the 6-2 - l .
parametric study is that[, llowever, there is 1 Instead there is a [
] which, produce the limiting case results.
The R0Pfl quoted previously (see Table 6.1-1) for the limiting CEAW event initiated at 102% of rated thermal power does not account for any axial pcwer distribution shift (AXPD) and the associated decrease in the integrated radial peak (Fg ). A detailed analysis was performed to determine the net R0P:1 change due to the axial shape shift and the decrease in F gas a function of initial axial power distribution. Figure 6.1-8 presents the axial shape shift as a function of initial AXPD. Figure 6.1-9 displays the corresponding decreases in integrated radial peak. Both the axial shape shift and the initial AXPD are characterized by exial shape indices. The net penalty factor, 8 3, as a function of initial Axial Shape Index is given in Figure 6.1- 10.
~
The recults of the analysis indicate that . axial shapes cause the maximum axial peak shift and thus result in the largest penalty factor. The results also indicate that for a CEAW event i
'nitiated at 102% of rated power with an axial shace index more
[ and the penalty factort shown in Figure 6.1-10 are combined with R0Pli quoted previcusly in Table 6.i-1 to _obtain the tctal DNS margin degradation as a function of initic.1 ASE. Table 6.1-2 and Figure 6.1-11 presents the final R0Pri as a function of initial ASI at 102" of rated power. 6-3 .
The results of the parametric analysis in CEA reactivity insertion rate, MTC and H ,p and initial axial power distribution at 102" l pf rated power indicates the following:
- 1. [ This section describes C-E proprietary r
- ethods used in the analysis of ROFM.
( l l l
]
- 2. For the CEAU event initiated at 102" of rated power, the above occurs for a f .-
].
- 3. HTC's result in self limiting CEAN events, i
Thismeans[. ' d
- 4. ap/*F produce a reactor trip i
1 .
- 5. A net penalty factor of ) power at an ASI of ( ]hastobe applied to the ROPM to account for the margin change due to axial shape shift and the decrease in the integrated radial peak.
However,
].
l l An analysis was also performed at lower pcwer levels to obtain R0PM as a function of initial power level. The values of CEAW rate, H ggp and MTC were chosen based on the para.Tetric analysis performed at 102*; power. Hence the [ ]and 6-4 -
an U.TC of [ ] Lo/ F was used to determine the CEAW
~
rate which allowed 4 The results of the CEAW event initiated at 70% and 50% of rated power are given in Figures 6.1-12 and 6.1-13. The maximum R0PM is obtained at 70% and 50% of r'ted power for reactivity
- insertion rates of [ ] oo/incil and [ ]oo/ inch, respectively.
These CEAW rates in combination with the [
] and an MTC of [ -] oc/ F allow [~
by the excore detectors to rise and achieve a new steady state
]
The R0FM for the liniting cases initiated at 70% and 50% of rated power are presented in Table 6.1-3. ' The R0PM quoted in Tible 6.1-3 for the 70% and 50% power cases do not account for any axial shape shift or the decrease in the integr1ted radial. For the CEA!I event initiated at 70" of rated peser, the axial shape shift and the decrease in the integrated radial are presented in Figures 6.1-14 and 6.1-15 respectively. The penalty factor that is applied to the R0Pf1 quoted in Table i 6.1-3 is given in Figure 6.1-16. l The results indicate that for a CEAll event initiated at axial r shape indices
, ], the margin loss due to axial share is more than offset by the margir gain due to the decrease in the integrated radial peak. Hence, there is a net margin gain for CEAU event initiated at ASI
].
6-5 -
1 1 1 1 l The penalty factor for an ASI ] is l combined with the R0fM quoted in Table 6.1-3 to obtain the i l final DNB margin degradation at 700 power rated power. Table I l 6.1-4 and figure 6.1 -17 oresents the final RnPM as a function nf ASI for the CEAW event initiated at 70% of rated power, i Fiqures 6.1-18 and 6.1-19 present axial shape shift and the decrease in the Fg as a function of initial AXPD for the l CEAW event initiated a t 50; power. The penalty factors are l presented in Figure 6.l-20 The resuits show that, i The CEAW event initiated at HZP produces a " spike" in the core heat flux and power. The limiting HZP case is obtained for the combination of [ ] which oroduces the maximum rise in core heat flux. This occurs for [
]. The ninimum transient DNCR for the limiting HZP case is 1.4.
The ROP!1 at the negat,ive extreme of the DNB LC0 band allec. sed at each power level are presented in Table 6.1-2 and Figure 6.1-21. The l sequence of events for these cases are presented in Tables 6.1-5 to 6.1-8. The responses of key USSS parameters during a CEAU event are presented in Figure 6.1-23 to 6.1-37. The excore 1 detector responses for the limiting cases at 1020, 70% and l 507, of rated power are presented in Figures 6.1-38 to 6.1-40. 6-6
The limiting safety analysis cases at all power levels (ex, cept lEP) are those where [ . r Hence, t 6.2 F_UEL CENTERLINE TEMPERATURE MELT SAFDL A paracetric analysis in CEAW rate and H was performed ap initiating the transient at 102% of rated power to determine the combination of these paramcters which produce the' closest approach to fuel centerline melt SAFDL. The results, which are presented in Figure 6.2-1, indicate that the maximtci PLEGR is obtained with the [
, ]. Based on the results at 102% of rated power, [ ]
was used to determine the PLHGR at lower power levels. l The PLHGR as a function of initial power level is presented in Table 6.2-1 and Figure 6.2-2. The transient core power variation at each power analyzed is presented in Figures 6.2-3 to 6.2-6. G-7
As Seen from Figure 6.2-2
. Hence, for these power levels, the fuel centerline lt temperatures (Tq ) are calculated to ensure that UO 2 temperatures are not exceeded.
i i I The T q calculations are perforned for only the liZP case, since the transient initiated at this power results in the longest power spike. The procedures used to calculate the maximum Tq are illustrated below for the HZP case. The peak power obtained for the HZP case is 144% of rated thernal power (See Figure 6.2-6) and the power " spike" lasts for 5 seconds. The average energy rise during this time period is equal to [ ]. (The values of FR,F7, F 3, FUtic used to calculate hot spot energy rise are given in Table 4-1). The T rise corresponding to this average energy rise is [. '] . The initial T at HZP is 532 F. 1 Thus, the maximum T q is equal to [ ]. This T temperature is below the U02 melt temperature of 4800*F at a i burnup of 50000 11ND/MT . Hence the fuel centerline melt SAFDL l is not exceeded even though the [
'].
6-8 -
,#e . m w.e , awi w- ew In sumary, [-
O l J. . l l l
+
l I l t i I l i t i 6-9 -
TABLE 6.1-1 REQUIRED OVERPOWER MARGIfl AT 102" 0F RATED P0'.iER d l
._ _j t
I I 6-10 .
TABLE 6.1-2_ l FlflfL R0PM AS A FUNCTION OF ASI AT 102", CF RATED THERMAL P01lER l l Initial ASI R0 Pit j Penalty Factor Final R0Pf1
-0.14 [ ] [ ] [ ]
-0.075 [ ] [ ] [ ] .
L 0.0 [ ] [ '] [ ]
+0.15 [ '] [ '] [' ]
r
+0.3 [~ ] [ ] [ ]
6-11 l r-
i l l TABLE 6.1-3 l R_FjulRED OVERPOUER MARGIll AT 70" AND 505 0F RATED THERMAL POWER Initial Power Level CEAW Rate f4TC H ga (% of 2700 Mut) (x10-4 ap/ inch) (x10-4 oc/0F) BTU /hr ntt2_op ggpg 70 [ ] [ ] [ ] [ ] i 50 [ ] [ ~] [ ] [ ] l I l l 6-12 -
~ ~ .-- , - , ,
TABLE 6.1-4 - FIfiAL R0Pli AS A FUNCTION OF ASI AT 70% OF RATED THERMAL P0' DER Initial ASI R0PM) Penalty Factor Final R0PM
.4 [' '] [-] [ ]
.15 [ ] [] [ ]
o [ ] [ ] [ ]
+.15 [ ] [ ] [ ]
+.3 [ ] [] [ ]
1 9 0 6-13_ _
TABLE 6.!-5 Sequence of Events for CEA Withdrawal Event Initiated at 102% of Rated Power Time (Sec) Event Value 0.0 CEAs begin to Withdraw _ 68.5 CEAs Completely Withdrawn 220 [ ] 220 [ ] 300 - [ '] O 4 300 [ ] 482 . , [ 3 6-14 .
TABl.E 6.1-6 Sequence of Events for CEA Withdrawal Event Initiated at 70% of Rated Pcwer Tine (Sec) Event Value 0.0 CEAs begin to Withdraw 164.4 CEAs Completely Withdrawn 250.0 [ ] 250.0 [ ] 33 0. [ -]
- P 4 310 .
[ ] 550.0 [' .]
\
o ( 6-15 -
TABLE 6.1-7 Sequence of Events for CEA Withdrawal Event Initiated at 50" of Rated Power Time (Sec}. Event Value
~
0.0 CEAs begin to Withdraw - 342.5 CEAs Completely Withdrawn - 400 [ ] 400 [ ] 429.0 [ ] 429:0 [ ]
, J 600.0 [ ]
l l l 6-16 .
TABLE 6.1-8 Sequence of Events for CEA Withdrawal Event Initiated at HZP Time (Sec) Event Value 0.0 CEAs 'cegin to Withdraw 34.1 Reactor Trip on High Power, % of 40 2710 MWt 34.5 Trip Breakers Open -- 34.9 Shutdown CEA's begin to Drop into Core -- 35.2 liaximum Core Pcwer, % of 2710 MWt , 144 36.5 Maximum Core Heat Flux, % of 2710 ftWt 68.4 38.6 Maximum RCS Pressure, psia 2366 l l I l I 6-17 i l
1 V TABLE 6.2-1 PL!!GR AS A FUNCTID'! 0F POWER LEVEL Initial Pcwer Level CEAW Rate H Initial PLHGR (~ of 2710 !!Wt) X10~4 op/ inch P [U/hr-ft_op 2 LHGR (KW/FT) APLHGP. (KW/F l 102 [ ] [ ] [ ] [ ], [' l 70 ] [. [~ ] [ ] , [ ] [ ] i 50 [ ] [ ] [ ] '[ ] [ ] HZP [ ] [ ] [ -] [ ] [. ] l l l II 1 6-18 -
6 f~
, I, i
I i i 4 A 1 I i i s i- - _ . , H__g u rc CEA WITHDRAWAL EVENT FROM 102%61-1 POWER R0PM (DNilR) vs CEA REACTIVIT'/ INSERTION RATE . L 6-19
T-i ! i l i I I i i I l l : l l l_ _ 1 CEA WITHDRA\'!AL EVENT FROM 102% Poi'!El Figure R0PM (DNBR) vs CEA REACTIVITY , INSERTION RATE o.1-2 1 6-20
I i l s l 4 i I l l
)
1 CEA WJTiiDRAWAL EVENT FROM 1027: POWER Figure
~
ROPM (DNBR) vs CEA REACTIVITY INSERTION RATE 6.1-3 l 6-21 ! I
1 I i ! l I i i i i
- i I
l l l l : 1 i : I ,
)
m CEA WITHDRA'llAL EVENT FROM 1027. PC'/!ER Figure R0PM (DNBR)vs CEA REACTIVITY INSERTION RATE 6.1-4 l l 6-22
e CEA WITHDRAV!AL tVtii!f FROM 102'b POWER Figure REQUIRED OVERPOVER MARGIN vs CEA . WITHDRAWAL RATE 6.1-5 6-23 1 ',-,,...,s..;.. ,mm.- . r r +=r tavamNam =me*** PP ' '~'"~s-'
'4:' '-' ' ' 'I ~~~
1 l l l 1 t l- . - l l l l l l l CEA WITHDRAWAL EVENT FROM 102% POWER Figure REQUIRED OVERPOWER MARGIN vs CEA WITHDRAWAL RATE 6.1-6 i G-24
- w* ,c. m - - " - :- - -- l -.-._,.,c x , ., c. .. .z . . . .. = r. ., . - 7,, .2 . : w ,. .---- v. - -
i i L-l l t l [ l r l I l CEA WITHDRAWAL EVENT FROM 102:': PO'.VEP Ficu re REOUIRED OVERPOWER MARGIN (DNBR) vs CdA REACTIVITY INSERTION RAE 6.1-7 6-25 i -. m_ a <, - , .. . , - .. . %n , _ 7 , , - . . _,,. , , , , , , ,_ ,
~
i l l CEA P!ITHDPAU!AL EVENT FROM 102% P01.'!ER Figure AXIAL SHAPc INDEX SHIFT vs INITIAL AXIAL ! SHAPE INDEX 6.1-8 6-26 w . . , . . - . . + -. _, ..r.. . s . . . ,. - + - . - . - + . .. .
r l l t 1 l l i i CEA WiiHDRAWAl. EVENT FROM 102.-: POWER Figure INTEGRATED RADIAL. DECREASE vs INITIAL AXIAL SHAPE INDEX 6,1-9 6-27 _ _ - _ _ _ _ . -yn, . - . , . .i. . . - ,
. . . _ , y m :- w .. . . _
+_ -.m.. _.. ...
j l t 1 l l l l l
~
I - l t I CEA V/ITHDRAWAL EVENT FR0ld 102% POWER Fioure PENALTY FACTOR ON DNS ROPM vs ^TNITIAL AXIAL SHAPE INDEX 6.1-10 6-28 k , . r . . , . m . . n . . . __ _. ,, _ c y v ,.c.. . . . ,_ ,,_ ,
e I 1 l l l CEA WITHDRAWAL EVENT FROM 102% POWER Figure ROPM (DNB) vs INITIAL AXIAL SHAPE INDEX 6,1-11 6-29 ,,, . .~ i ,-. ...; ~ m ,. - . . , r. . y a -- v.r --- v . - , . , , F , , , , - - - ~ - - - - - -
~ ~ ~ ~ ~ ~
Figu re CEA CITHDRA'."AL EWNT FRO l.1/UCCER REQUIRED OVERPC'?/ER MARGIN vs CEA V!1THDRAil!AL RATE 6.1-12 6-30 u-=r;. . . . -, . a , 5w r. . ., . . . a ; -, ;- , - :- ,. . .- cc., , - n:s., _ _nw:v - - - w a ,,, ;. --.,w -"n-
CEA WITHDRAV/AL EVENT FROM 50% POWER Figure REQUIRED OVERPOWER MARGIN vs CEA WITHDRAWAL RATE G 1-13 6-31
..n,=,,,
. , , ~ . . ,,, . i .a : , . . , , . ,
, , . ; , . . :.1 - ; .,..-,+.--+,-v,
. ,:.;,w.=,. , v::n. - .
. _!. tl/ITliD W/!AL EVEi!T Fi!O'.1 RU POV!ER Figure AX] AL Sliii-i INDEX SHIFT vs INITIAL AXIAL SHAPE INDEX E,1-14 U-32 m i . , . ,. .. ;, -s +- -.. . ,, - , -. . -nwmm
.. ,,, a = =,= w n-
CEA WITHDRAWAL EVENT FROM 7L W ER Figure INTEGRAED RADIAL DECREASE vs INI(IAL AXIAL SHAPE INDEX 6.1-15 6-33 _w , =,- .r ,. . , , , - .
,.- a . m m w . ...+b------,~.;. - - , . ~- ;c- - - -
4 1 i i I e 1 4 i 1 I l 1 l; l I l i i 1 CEA WITHDRAWAL EVENT FROM 70% POWER Figure l PENALTY FACTOR ON DNB R0PM vs INITIAL AXIAL SHAPE INDEX 6,1-16
-b-34 \
- 1. ;
' ~
- - - ;" 3 L'?'J ' U PTN b '7 N 5' " + ? '# '**M
nr , s r. . . . wenc ' r
CLi WITHDi'AV/AL EVENT FRO l170; POWER Figure ROPA1 (DNBR) vs INITIAL. AXIAL SHAPE INDEX 6,1-17 6-35
- y
- 2. ..7,- .--
...7 - , . _ - _ , . .>-4.
, -.,- u se_ . _ - . . , . _
1 CEA WID1DRAV!AL EVENT FROM 50:' Pot!!ER Figure AXIAL SHAPE SlilFT vs INITIAL AX1AL SHAPE INDEX 6.1-18 6-36 4.- c - - ._ .. . .m - ,. - ,m. - , , . . . , ~ - - . . - - . - - - 2. e4 .. , - - .., z .- s , , . . - - .-
CEA WITHDRAt!.'AL EVENT FROM 50' PO'?.ER Fiaure INTEGRATED RADIAL DECREASE vs DH IAL AXIAL SHAPE INDEX 5,1-19 6-37 +. ,- w..~a , ,., i - ..e m m m m m m e. - - ,n~ ~z.wer. -
. ,--, ~ - - - - . mm ~-
L_ __ GA WIT!!0RA'.'!AL EVE:.'T FRO?.i 50" POWER Figure FENALTY FACTOR 01 DNC R0P',i vs INITIAL AXIAL SHAPE INDEX 6.1 70 4 6-38 c-.,m..me_; -, _ -. . ,,,__;.,__;,-=,.m,,_._.._._-
,, ,_ _.s
7- .- CEA WITHDRAWAL EVENT Fiq~ u re REQUIRED DVERPOWER MARGIN vs INITIAL POWER E.1-21 6-39
-,, . i., an = . . - . - . . - - ~ - , - - =
v ~ : ~ c . . . --- . ---,n -- - o ~ ,- -
CEA WITHDRAWAL EVENT FROM 102% POWER ricune CORE POWER vs TIME 6,1-22 . . _ _ ..._ _ . _m__ .m _ .- - - -
e u 1 l l 1 i 1 CEA WITHDRAWAL E\"~.# FROM 1027a POWER Ficunt CORE AVERAGE HEAT FLUX vs TIME 6,1-2;- s 6-41 _' I I. _ 7"_'~ "u "-
.. g " " - ^" . . - -
g, , ; 4- u_._, _ ,,o 7h
l l l CEA WITHDRAWAL EVENT FROM 102" POWER FIGURE RCS TEMPERATURES vs TIME G,1-24 6-42 m,mmyr-m+ cm :i "; . ,, - ~ myov.; ' - * ' - - - - - m r w'- - ~ " -
S -. CEA WITHDRAWAL EVENT FROM 102% POWER Figure RCS PRESSURE vs TIME E ,1 9.c.. 6-43
.-8 --;. r v;ccng r- ,- ,yxy=.r,7 , : --. -- z. , . - -y n. , -.; r.,,e +
. , a : . ., , - - --
1 _ FIGUR E CEA WITHDRAWAL EVENT AT 70% POWER CORE POWER vs TIME 5.1-26~ 6-44
t FIGURE l CEA WITHDRAWAL EVENT FR0i.170% POWER CORE AVERAGE HEAT FLUX vs TIiME G 1-27 1 6-45 j
CEA WITHDRAWAL EVENT FROM 703 POWER FIGUilE RCS TEMPERATURE vs TIME C,1-26 I 6-46
- __- - =-_....._--_. -== m-----
-=-
CIU. !ITilDRAWAL EVENT FROM 7070 POWER Figure RCS PRESSURE vs TIME 6.1-29 6-47 _ . . . . - - , , , - , , 7. . .: .v u : . . - - - ~ ~ ~ ~ , - - l
.-- ,=w - . 2 - =c .. . .. ., + -: . .~v. . - - - - -
- CEA WITHDRAWAL EVENT FROM 50':'; POWER FIGURE CORE POWER vs TIME 6,1-30 6-48 mm,, , -- m.-,.,,, ,, _x = , .-m,.+.-
= = -ww : .-
-m -e
CEA, WITHDRAWAL EVENT FROM 50% POWER ricune CORE AVERAGE HEAT FLUX vs TIME 6.1-31 6-49 h____,_,..,_. .
. ~ -.
- - - a _, m;. -w - - -- -- - _ ----- -
CEA WITHDRAWAL EVENT FROM 503 POWER FIGURE RCS TEMPERATUEE vs TIME 6.1-32 6-50 ____f.q.,--+
,- , .,- - ,.---;wm mmae
.s
==mr ....., m e m-mr-evw - ... ..-,,r,-- -
-- .-~--j
l CEA WITHDRAWAL EVENT FROM 50:LPOWER Figure RCS PRESSURE vs TIME 6.1-33 l 6-51 g Um-L - 7.' A" E 7. =5 m D *, r',', 7 'T'-'r"I'sm - fr 7-4 e i, - .m y , iv , , g %m ,, -h _ __m_ j'
160 , i i , i i i i i 140 HOT ZERO POWER e-6 120 E m 100 u_ o tn 80 - - cs W 60 - 6 c_ g 40 - - o O 20 - - l l 0 ' ' - ' ' ' !- - ' - O 10 20 30 40 50 60 70 80 90 100 TIME, SECONDS l 1 CEA GROUP WITHDRAWAL EVENT- FIGURE CORE POWER vs TIME 6,1-3!i 6-52 l
.--,- % .; . -. - c -- - w-=- . - - - -
vm - + - = - - - g 77 7._ - ; . - ,
70 , , , , , , , , , s I 60 - HOT ZERO POWER _ 2 Ci 50 - - it m LL o TN
. 40 - -
x a L.a w I 30 - w a c w w m 20 o O 10 - 0 ' 0 10 20 30 40 50 60 70 80~ ~ ~90 100 TIME, SECONDS CEA GROUP WITHDRAWAL EVENT FIGURE CORE AVERAGE HEAT FLUX vs TIME E.1-35
. = -
6-53 cmwn u:[ .i r, ~.c:nmsp n.nnav<ww- ,- - , ,,. . . w r .x .
.--.,------.v-:
l
. -. _= . _. . ... -. .. . ._ . _ --
c-t L t
- 575 , , , , , , , , ,
- u. -
i
- 570 -
- m y j
M ' OUT
~
565 - T j F2
,\
AVG e -- T IN E j 560 - h - 3 555
- b!
! 5 550 A Y -
\\ -
~
545 l 3 o
't i
o I1 - o 540 -
' 1
\
i x pm h 535 -
'? -w -
t tJ 4' % ,j.f 530 O 10 20 - 30 40 50 60 70 80 90 100 TIME, SECONDS l i r FIGURE CEA WITHDRA1NAL EVENT FROM HZP LRCS TEMPERATURE vs TIME .E.1-36 6-54 E- --c. . - - + . .
1 4 t
- 9 2400 , , , , , , , ; ,
{
< HOT ZERO POWER
. Gi
! 2350 - - LAI e a :
; m >
m LM e
- ! a 2300 -
- hm i
- m i M 2250 -
i 5 O O
- o m J p 2200 -
o LLJ e 2150 ' ' ' ' ' ' ' ' ' , 0 10 20 30 40 50 60 70 80 90. 100 TIME, SECONDS i 5
.CEA GROUP WITHDRAWAL EVENT FIGUR E 4
REACTOR COOLANT SYSTEM PRESSURE vs TIME 6.1-37 I 6-55
..r+4,.6 7. s'7 hi . I e. e'D 3 ** 2 3 . ' * -* -{f- y',#' *
- 6 6 -*2' ' " "i l ~ ~~~ U M C. + ' ' ' # ' M ' T *- #' b ' '. W"
~
',****** r + , - , ~ ~ .
l l l l l l l CEA V!ITHDRAWAL EVENT FROM 102/ P0YlER FIGURE EXCORE DETECTOR POWER MEASUREMENT vs TIME 6.1-38 l O *s u i 1 -7.- c ss.-.--c.--,.,,..,7-
. . -----y.,
, , , - , pg.y , . . ., _ _. y ..,,_ ._
_.__g,__ ,,,, ,
CEA WITHDRAWAL EVENT FROM 70a POVER FIGURE EXCORE DETECTOR POVER MEASUREMENT vs TIME 6.1-39
~ 6 - E,T
, 7 s. e A- { i r .,. ~. y > .;-,n . g ,iw - y- ; -- -- -4 , @,,,,..E,.--,-----%-- 7"&--<.------ ;4*"'
FIGURE CEA WITHDRAWAL EVENT FROM SQL POWER 6,1 !!0 EXCORE DETECTOR POWER MEASUREMENT vs TIME. 6-58 t M~ ~ H+F.WWW*WF'My **M** t.hMVfi9t*MWT e= 's [hy g@;MTM.Nmyr@ , ;-
-,_m-, c ,,. .. u
l 1 i i I ) 1 l I i i I 1 l l l i FIGUl(E . ; CEA GROUP WITHDRAWAL EVENT PEAK LINEAR llEAT GENERATION RATE vs Hgap 6.2-1 ,
- 6:59 n .- . - gw , ; =. .;. 7 -,; , . , -, ., , n . , . .
. . . , .. , ...--_- . . m - .. c
\
J' l 1 CE.r,.o Li.n e. ,.r i l iti r"u,. v . Di onu vl o s . .t,,\ t.-rs,tL:u ricune > A 1 Ce n. ,nRiu i0e.j n Pu-,sa,,iIn.,o,sn.,1, sa nn, ,i t vs Ir,.e1T.in- . , P,ol. .c zu R ')
- c. 9 -
6-60 , , , . , , , .+s.,~-,.
,, .., , : .. , ;. ._.y = .- O . = , = = :n -. a rw:- ,-- ,,a.
- v. .,.>~:.. ~ M~
f
~ 120 4 I i i 1
100 - - 4 4 l 5 80 - - i 1 2 i N u. o te 60 - -
- c2 i
te 8 ca. i M 40 - - o o 20 - J 0 i i i i t 0 4 8 12 16 20 TIME, SEC0tfDS - 1 i
- CEA WITHDRAWAL EVENT FROM 102% POWER Ficune
~
- . CORE POWER vs TIME- 6,2-3 - ,
6-61 4 or e- - +- r -
--r%v
-w -v
o : ,
- l. '
1 1 )
- i .
90 . , . , . . . . . 1 80 - -
~
I, s_.
; -c ca 60 - - ! it ; m u_
i o - - e
. c2 40 - .i W.
o
; a - -
i LtJ CE o a 20 0 . ' . ' . ' . ' . 0 10 20 30 40 50 . TIME, SECONDS 4 l i- l 1 l i l CEA WITHDRAWAL EVENT FROM 70% POWER riaune - CORE POWER vs TIME 6 , 2 11 ~ 6-62 l
100 . 80 - -
=
55 - - o C u 60 - - O C[ Lu [j 40 - a- I w e . i o U 20 - - 0 - ' ' ' ' ' ' ' ' 0 4 8 12 16 20 TIME, SECONDS l 1 l s:- CEA WITHDRAWAL EVENT FROM 50"c POWER FIGURE CORE POWER vs TIME 6,2-5
. e-63
160 . , . F . r4-
- E 120 -
o 8% N . L2 . O til
, 80 -
e ; L t.1 9: o - CL w N O 40 - C3
~
0 - ' D *-- r- = A - ' 0 20 40 60 80 100 TIME, SECONDS CEA WITHDRAWAL EVENT FROM HZP noune CORE POWER vs TIME 6.2-6 6-64 g I
- 7. _C0flSERVATIS'tS Ifl AtlALYTICAL IfETH005 The purpose of this section is to identify the conservatisms that are included in the methods used to calculate the R0PM on 0:lBR and peak linear heat generation rate. (These conservatisms are qualitatively identified below), Example cases are presented and i
compared with the safety analysis results of previous sections to i quantify the conservatiscs. ! i
- 1. The power input to the high power trip (HPT) and the variable high power trip (VHPT) is the auctioneered higher of the neutron flux power (measured by excore detectors) and the thermal power ,
(measured by the AT-Power Calculator). [. , i
]. The analysis assumed a reactor trip '.s initiated on the HPT cr the VHPT [
- f
-]..
- 2. The CEAll event initiated at 102% of rated power assumed a HPT setpoint of 112% of initial power. This includes a transient decalibration uncertainty of 3%. The transient decalibration of the excore detectors which is explicitly accounted for in the safety analysis is less than 3%.
- 3. The fiTC is not expected to be positive except for the first few ;
hundred.fi.!D/f1T. This cccurs only at zero power. 1 i l
- 4. The H value is higher than expected on a core average basis g3p at the end of a given reload cycle.
7-l '
- 5. The calculation of PLMCR used the maximu:1 value for CEA reactivity insertion rate. This .ruximtu value is higher than expected for any reload cycle.
- 6. Incomputingmarginrequirements.[
]. .
7.1 C0flSERVATISMS Ifl Otm R0PM CALCULATI0f;S To quantify the conservatisms outlined above, two "best estimate" cases were run. The first, initiated at 100% of rated power and the second initiated at 50% of rated power. A comparison of the input data used in the safety analysis cases described in Sections 5 and 6 wit,h that used in the best estinate cases are presented in Table 7.1-1 and 7.1-2. The sequence of events for the best estimate cases are presented in Tables 7.1-3 and 7.1-4. A comparison of the R0Pil's for the best estimate case and the safety analysis cases are presented below. Initial Power Level (% of 2710 Mut) R0PM (5 of Initial Power) Best Estimate Safety Analysis 102 [' ] [' ] 50 [' ] [ ] The above comparison shows that the safety analysis R0 Pit's are at least [ ] conservative with respect to the best estimate results. The results of best estimate analysis at 1027. of rated pcwer shows that the power and heat flux rise but the increasing coolant temperatures ia combination with the 7-2 - e , J M w
negative ftTC adds negative reactivity which reduces the power and heat flux to their initial .yalues and achieve a steady state condition. The response of the !!SSS for the best estimate cases are' presented in Figure 7.1-1 to 7.1-8. , 7.2 CONSERVAlIStiS IN PEAK LINEAR HEAT GENERATION RATE The conservatisms in the PLHGR calculations were quantified by performing best estimate cases. The first, performed at 102% of rated power and second perforned at HZP. The transient core power rises for the best estimate cases are presented in Figures 7.2-1 and 7.2.2. A comparison of best estimate and safety analysis results are presented below. Initial Power SAFETY ANALYSIS BESTESTIfiATEANALYSIS! PLHGR PLHGR
% of 2710 ftWt APLHGR APLHGR 102 [ 2 [' ] [' 3 [' ]
HZP [ 3 I 2 [ ] [ '] The results show that at full power the PLHGR is conservative by [ ] This due to the conservative value of CEAU rate assumed in the safety analysis to bound all ft-. ore reload cycles. The resuits . also show that the steady state limit of 21KW/ft is exceeded for the best estinate case. This is to be expected since at HZP, the transient produces a-pov.er suike. A calculation was-performed to determine the_T and results are given below. 7-3 '.
- ~.
~ - ' <
l r Average tE Hot Spot aE AT rise T T rise (STU/lbm) rise (BTU /lba) F k k op og Safety Analysi: [ ] [ ] [ ]_ 532 [ ] Best Es tima tr Analysi: [ 3 [ ] [ ] 532 [. ] The results show that the T q calculated is conservative by at least [ 1. Hence based on this comparison we can conclude that the results l presented in Section 5.2 are sufficiently ccnservative. i l l
. 7-4 .
TABLE 7.1-1
! KEY I!1PUT PdRA!:ETERS USED Ifl CFAW EVEtlT AtlALYSIS 'ilITIATED FRC't 102*; POWER Safety Analysis Values Safety Analysis with Identified Paraceters Units Values Conservatisms Eliminated t
Initial Power level % of 2710 f Wt 102 < 102 ** fnitial Inlet *F 550 -< 550** Temperature Initial RCS Pressure psia 2200 ~
>22 00**
6 ') Initial Core Flow X10 ltn/hr-ft" 2.53 >2.53** Moderator Temperature X10-4 Ap/ F [ ] [ ] Coef ficient - 2 Gap Thermal BTU /hr-ft - F [~ ] [ ] Conductivity CEA Differential Ucrth 10'4 Ap/ inch [ ] [ ~] CEA Uithdrawal Speed inch / minute 30 30 CEA North at Trip % ap -4.6 >e5.8** High Power Trip % of 27i0 !!Wt 112.0 109.0 Setpoint l Integrated Radial, Fg 1.65 1.65 \! l Temperature Shadoinng Factcr
% power / F [ ] [ ]
i AT-Power Setpoint (2,5, ,ll l Coefficients (a, T) i Axial shape Index [ ] [ ]
- liOT TAKEll CREDIT FOR I'! SAFETY At ALYSIS
** Results insensitive to initial values for these parameters.
7-5 '.
l TABLE 7.1-2 5 . KEY IllPUT PARAMETERS USED If1 CEAU EVEllT A?ALYSIS I!!ITIATED FROM 50~ POWER Safety Analysis Values Safety Analysis With Identified l Parameters _ Units Values Conservatisas Eliminated
; Initial Pcwer Level % of 2.710 MWt 50 50 , )
Znitial Inlet 'F 540 -
< E 40**
Tcmperature - I initial RCS Pressure psia 2200 > 2200** 0 Initial Core Flow X10 lbm/hr-ft 2 2.53 > 2.53** Moderator Temperature X10'4 Ap/ F [ ] [ ] Coefficient Gap Therral GTU/hr-ft -?F [~ ] [ ] Conductivity f . l CEA Differential Worth 10-4 Lp/ inch [ ] [ ~] CEA Withdrawal Speed inch /n.nute 30 30 CEA North at Trip % Ap -3.4 >-4.3 High P'ower Trip % of 2710 MWt 60 60 Setpoint j Integrated Radial, F R 2.0 2. 0 ** l Temperal.are Shadowing % power /"F [ -] [ ] Factor AT-Power Setpoint * (2.5,.1) Coefficients (a, T) Axial Shape Index [ ] [ -] l l cNot taken credit for in safety analysis. l 0 Results insensitive to initial vcfues for these parameters. l l 7-6 ,
] TABLE 7.1-3 i
SE00Et:CE OF EVEriTS FOR ( CEA WITHDRAWAL EVEtiT IttITIATED AT 102% OF RATED P0"ER (Best estimate) f TI!:E EVENT VALUE
\ -
I 0.0 CEA's Begin to Withdraw - 68.5 CEA's Completely ilithdrawn 69.5 11aximum Power, % of 2710 ffdt 103.5 I l l 73.0 Maximum Heat Flux, % of 2710 M'It 103.4 125.0 l'aximua Inlet Te:roerature, F 552.7 128.0 liaximun RCS Pressure, psia 2274 158,0 Core Power Returns to it's Initial Value, % of 2710 if.it 102 166.0 Core Heat Flux Returns to it's Initial Value, % of 2710 MWt 102 l 1 l l 7-7 -
r TABLE 7.1 - 4 SEOUENCE OF EVENTS FOR CEA UITHDRAWAL EVENT IMIT!ATED ,u 50% OF 7
~
RATED POWER t
! (Best estimate)
TI"E EVENT VALUE 0.0 CEA's Begin to Withdrati 55.0. Reactor Trip on High Power .60% 55.4 Trip Breakers Open Shutdown CEA's Begin to Drop into Core
- l 55.9
'l
!56.2 11aximum Power, % of 2710 M'dt 62.0 '
56.7 Itaximum Heat Flux, % of 2710 MUt 61.3 1 j57.4 Itaximua RCS Pressure, psia 2353 l
, 70.5 fiaxir.um Inlet Tcaperature, *F 548.2 I
i i i - 7-3 . 9
140 , , , , , , ,
, , i i 130 - -
~ 120 -
=-
e . S 110
~
CN t.t ' o 100 - 1:< c2 90 - W O o- 80 - LJJ CL o .,0 o / -
/
60 - c ' ' ' ' ' ' ' ' ' ' '
'0 275 300 0 25 50 75 100 125 150 175 2C0 225 250 TIME, SECONDS b
. v., l 9
CEA WITHDRA'/!AL EVENT FROM 102% POWER Figure CORE POWER vs TIME 7.1-1 7-9 1
. t
.\ .
=g 120 , , , , ,
~ .
Q . r a 110 - u .- O tt 100 - x' 3 u 90 - - I-to - - x 80 w a e 70 L.LJ
< 60 - -
w - K
" 'O 0 50 100 150 200 250 300 TIME, SECONDS CEA WITHDRAWAL EVENT FROM 102?e POWER Figure CORE AVERAGE HEAT FLUX vs TIME 7.1-2
, 7-10
f
* .t
, , /' i m
g 610 , , , , , , , , i 4
.i o
n y
= T ~
55 600 . OUT LLJ '
- a. .-
y590- . a W 580 - - m g T AVE i- 570 - - z 5 o o 560 - - o c= o 550 T i- .IN . o
$ 540
" 0 25 50 75 100 125 150 175 200 225 250 275 300 TIME, SECONDS r
e.*g CEA WITHDRAWAL EVENT FROM 102. JOSER Figure RCS TEMPERATURE vs TIME 7.1-3
, . 1- n e
a .
}
2280 > i > > > , i i i i i i w 2270 - _ cc - . a w - m 2260 - - y . c - s 2250
\d w -
w 2240 l-- ' z - -
-5 2230 "O
O o 2220 - - cc E2 o 2210 - - 6 a: 2200 - .
' ' i 1 ' ' ' i e i i l 1990 25 50 250 300 0 75 100 125 150 175 200 225 275 TIME, SECONDS .
r t. CEA WITfiDRAWAL EVENT FROM 102% POWER Figure RCS PRESSURE vs TIME 7.1-4 7-12 4 .'
s, .. .
'100 . . . . -
90 - i ,. / i , 80 - 3:
- E 70 -
O i' U 60 - o S0 N ~ of W 6 c. 40 - - UJ or o 30 - o 20 - 10 0 ' ' ' 0 20 40 60 80 100 120 140 160 180 200 TIME, SECONDS r -
~
CEA WITHORAV!AL EVENT FROM SQL POWER Figu re CORE POWER vs TIT.iE 7,1-5 7-13 y .
100 . , , . 90 - y? .
. i ,' ,
3 80 - O
- r=
, "u. 70 -
p - tt
. 60 r 1 -
x - aJ ' m 50 - s u; I 40 w a z 30 LLJ w e 20 - - o
~
10 0 ' ' - ' 0 20 40 60 80 100 120 140 160 180 200 TIME, SECONDS
.n; CEA WITHDRAWAL EVENT FROM SM: POWER Figure CORE AVERAGE HEAT FLUX vs TIME 7.1-6
, /-14
t . 8- 580 -
, . . . .~ ,
t$ '0UT . e 570 - -
. p -
< T
,5 560 -
AVE - P: m W 550 I
- 2 IN
$ 540
- ~ . ._ _ _
m H z 530 5 8 520 u x
. o s 510 -
a .- y . t4
' 500 0 20 40 60 80 100 120 140 160 180 200 TIME, SECONDS
,c .:
CEA WITHDRAWAL EVENT FROM 50% POWER Figure RCS TEMPERATURES vs TIME 7.1-7 7-IS 4 .
l g
\ . .
2400 . , . . , . . . 5 2300 w a. L2I ,
?! .
$ 2200 - -
w - x - C- .
- E .
Ii w -
>- 2100 -
m W Z . 5 a 8 2000 - e F? ./ ! o / .
" 1900 .
1800 l 0 20 40 60 80 100 120 140 160 180 200 TIME, SECONDS , J CEA WITHDRAWAL EVENT FROM 50% POWER Figure
. RCS PRESSURE vs TIME 7.1-8 7-16_
\ . .
120 '
- i i i .
+
100 - _
~ c.
p e0 . b . O N N LL 60 - in of W Et: o u. w 40 - - x o - O 20 .- O i i i i 0 4 8 12 16 20 TIME, SECONDS y CEA WITHDRAWAL EVENT FROM 102i'a POV!ER Figure CORE POWER vs TIME 7.2-1 4
. 7-17 .
O
t
, 140 , , , , , , , , ,
t r 120 - 55 a
,e 100 -
N LL. O 80 -
. . t*
~
S3 60 - - E: o to 40 - CE o o 20 - 0 ' ' ' D ' h- ' ' ' ' ' 0 10 20 30 40 50 60 70 80 90 100 TIME, SECONDS S a CEA WITHORAWAL EVENT FROM HZP Figure CORE POWER vs TIME 7.2-2 l
. 7-18 .
, . .j
- 8. CONCLUSICMS The High Pcuer and Variable Hich Pcwer Trins and the incorporation of the CNB and LHR R0PM's in generating the DNB and LHR limiting conditions for operation ensures that DNB and CTM SAFDL's will not be exceeded during a CEAW event. The peak linear heat generation rate does not exceed the steady state LHR limit for CEAW transients initiated above 50% of rated power. The steady state LHR limit is exceeded for power levels below 50% of rated power, however foal centerline temperature melt will not occur. Hence, the results support reclassification of the CEA withdrawal event frem the category
. requiring the TM/LP and ASI trips to the category where sufficient initial thermal margin is built into the LC0's to ensure that DNB and LHR SAFDL's are not exceeded when only the high power or variable high power trips are credited as possible trips to mitigate the event. t . f l 4 8-1 . 4
- 9. PEFERENCES ~~
- 1. CEllPD-199-P, "C-E Setpoint liethodology", April, 1976.
- 2. CEllPD-107, CESEC Topical Report, July 1974.
- 3. CEllPD-161-P, " TORC Code, A Computer Code for Determining the Thermal liargin of a Reactor Core", July 1975.
- 4. Systera 80 PSAR, CESSAR, Vol.1, Appendix 4A, Amendment No.3, June 3,1974.
- 5. Brasfield, H. C., et al "Reccmr, ended Property and Reaction Kinetics Data for Use in Evaluating a Light Water Cooled Reactor Loss-of Coolant Involving Zirculoy - 4 or 304-SS Clad U0 ", GEMP-432, M68.
2
- 6. SHADRAC, " Shield Heating and Dose Rate Attentuation Calculation",
G30-1365,!1 arch 25, 1966.
- 7. W. Engel, Jr. , "A User's fianual for ANISN", K-1693, March 30,1967.
l 9-1 ",
'l
1
- 10. APPENDIX METHODS USED TO DETERMINE EXCORE DETECTOR RESPGl;SE DURING A CEA WITHDRA'.!AL EVENT The neutron, flux power measured by the excore detectors during a CEA i
withdrawal event can be calculated by the following expression:
- N"ESH -
Excore Detector i I AXPD.
- RSF. ' (t) i
= ' i=i 1
- 1 + TSF
- aT ( t )
Response (t) 7;;3g3g (* PEquation (t) 1-1
'l r AXPD.
- RSF. (t=0)
( i=i l 1 where: NMESH = number of axial nodes the core is divided into, which is equal to 20. RSF j = red shadowing factor appropriate for the i th node normalized average power in the i th node l AXPD j = j TSF = temperature shadowing factor aT (t) = Tin (t) T in (t=0) P (t) = actual core average pcwer at time t. l , The rod shadowing factor for a given CEA bank is defined as the ratio l of the excore detector response for full insertion of that bank to the excore detector response when all rods are out. The RSF's are determined using detailed two-dimensional power distributions representing the cumul-ative presence of the various rod banks and the shielding code SHADRAC (Reference 6 ). In this application SHADRAC calculates fast neutron spectra and fluence for the excore detectors in a three-dimensional system utilizing a moments method solution of the transport equation. The core, vessel internals, vessel and excore detector locations are treated explicitly in the calculation. A-1 -
The Temperature Shadowing Factor accounts for t go temperature dependent effects on the excore detector responses. These are:
- 1. The effect on detector responses due to varying water density from moderator temperature changes. These are calculated by using computer code ANISN (Reference 7). From ANISN the percent change in detector response per degree change in moderator temocrature is calculated.
- 2. Detector response sensitivity to power shifting due to
, moderator terperature changes. This is calculated by applying the assembly weighting factors calculated frem SHADRAC analyses to the PDQ power maps representative of two moderator temperatures.
Again the percent change in detector re'sponse per degree change ! in moderator temperature is calculated. Tne total Temperature Shadowing Factor (TSF) is the sua of the above centioned effects. . A-2 -}}