ML20235M221

Nonproprietary Rev 01-NP to Modified Statistical Combination of Uncertainties

ML20235M221
Person / Time
Site:	Palo Verde
Issue date:	07/13/1987
From:	Haynes J ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY, ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:
Shared Package
ML17303A482	List: ML20235M221
References
CEN-356(V)-NP, CEN-356(V)-NP-R01, CEN-356(V)-NP-R1, TAC-65460, TAC-65461, TAC-65462, NUDOCS 8707170112
Download: ML20235M221 (41)

Text

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4 MODIFIED STATISTICAL COMBINATION OF UNCERTAINTIES e

CEN-356(V)-NP REVISION 01-NP JULY 1987 i

i NUCLEAR POWER SYSTEMS ,

COMBUSTION ENGINEERING, INC. l

- WINDSOR, CT.

I i-P u__ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

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i LEGAL NOTICE  ;

, ; THIS REPORT WAS PREPARED AS AN ACCOUNT OF WORK SPONSORED BY COMBUSTION v_ ENGINEERING, INC. NEITHER COMBUSTION ENGINEERING NOR ANY PERSON ACTING ON ITS BEHALF:

l' 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 PROCESS DISCLOSED IN THIS REPORT MAY NOT INFRINGE , .,

ON PRIVATELY OWNED RIGHTS; OR 9

B. -ASSUMES ANY LIABILITIES WITH RESPECT TO THE USE OF, OR FOR DAMAGES I RESULTING FROM THE USE OF, ANY INFORMATION, APPARATUS, METHOD OR PROCESS DISCLOSED IN THIS REPORT.

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'l ABSTRACT e

,. f Modified Statistical Combination of Uncertainties This report describes changes to the methodology- for statistically I l

combining uncertainties used to determine the LSSS and' LCO overall

{

uncertainty factors for C-E's digital monitoring and protection systems. '

The resultant overall uncertainty factors using the Modified Statistical Combination of Uncertainties (SCU) Program are determined and applied such that the Core Operating Limit Supervisory System (COLSS) Power Operating i Limit (POL) and the Core Protection Calculator System (CPCS).DNBR and Local Power Density (LPD) calculations are conservative to - at least a 95/95 probability / confidence level. The changes do'not impact either the manner  !

in which COLSS. aids the operator in maintaining operating margin to limits j on linear heat rate (LHR) and DNB or the manner in which the CPCS. responds  ;

to transients and provides the low DNBR and LPD trips. Therefore the changes do not impact transient analysis assumptions or results and do not

,- involve changes to Technical Specifications.

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(i) l E - - _ _ _ _ _ _ _ _ _ - _ -_ - - _ .

I TABLE OF CONTENTS l

CHAPTER PAGE 1

i

1.0 INTRODUCTION

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1.1 Purpose 1 1.2 Background 1 1.2.1 Protection and Monitoring Systems 1 1.2.2 Current SCU Program 2 1.3 Modified SCO Program 4 l

1.4 Summary of Results 5 2.0 METHODS 11 2.1 Introduction 11 2.2 System Parameter SCU Methodology 11 2.3 Secondary Calorimetric Power Measurement 13 Uncertainty Methodology 2.4 CPC Neutron Flux Power Synthesis Uncertainty 14 Methodology

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2.5 Other Modifications to SCU Methodology 15 2.5.1 Radial Peaking Factor Measurement 15 Uncertainty Application 2.5.2 Application of Uncertainty Factors as 16 a function of Burnup, ASI and Power.

(ii) w . _ _ _ _ _ _ _ _ _ . _ - _ _ _ _ _ _ _ _ _ _ _ .

TABLE OF CONTENTS (Cont'd)

CHAPTER PAGE 3.0 TYPICAL OVERALL UNCERTAINTY FACTOR CALCULATION 18 3.1 Introduction 18 3.2 DNBR pdf 18 3.3 Secondary Calorimetric Power Measurement Uncertainty pdf 19 3.4 COLSS DNBR Overall Uncertainty Factor 19 Calculation 3.5 CPC DNBR Overall Uncertainty Factor Calculation 20 ,

4.0 CONCLUSION

33

5.0 REFERENCES

34

• I 4

(iii) 1

-_ _ __ _ _______a

, c. ~

i.

l LIST OF TABLES I TABLE PAGE'

. l 1-1 Uncertainties Included in the System' 6 i Parameter'SCU -l

-. i 1-2 General' Categories of Uncertainties. Included. 7 in the State Parameter SCU 3-1 Components Combined in the DNBR'pdf 22 3-2 Secondary Calorimetric Power Measurement 23 Uncertainty Components 1

3-3 COLSS State Parameter Ranges and Measurement 24 Uncertainties ._,

3-4 Uncer+aintyComponent[ 25

]inCOLSS DNBR Uncertainty Analysis 3-5 UncertaintyComponents((

to Determine COLSS DNBR Overall Uncertainty

] 26 Factors 3-6 CPCS State Parameter Ranges and Uncertainties' 27 3-7 UncertaintyComponent{ 28

]inCPCDNBR Overall Uncertainty Analysis

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3-8 Uncertainty Components I to 29 Determine CPC DNBR Overall Uncertainty Factors 1

(iv)

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LIST OF FIGURES i

FJGURE PAGE I

l 1-1 COLSS and CPCS Uncertainty Analysis for 8 i

• 1 Current SCU

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1-2 Current SCU Program Schematic 9 1-3 Modified SCU Program Schematic 10 j l

2-1 Secondary Calorimetric Power Measurement 17  !

Uncertainty l,

3-1 DNBR Probability Density Function 30 3-2 COLSS DNBR Overall Uncertainty Analysis with 31 Modified SCU _,

3-3 CPC DNBR Overall Uncertainty Analysis with 32 Modified SCU l l

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. l (v) 4

I DEFINITION OF ABBREVIATIONS ASI Axial Shape Index BERR1-4 CPC Overall Uncertainty Factors BPPCC Boundary Point Power Correlation Coefficient .

C-E Combustion Engineering, Inc.

CEA Control Element Assembly CETOP-D CE Thermal-Hydraulic Design Code

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CHF Critical Heat Flux CIP CPC Improvement Program CPC Core Protection Calculator CPCS Core Protection Calculator System COLSS Core Operating Limit Supervisory System DNB Departure from Nucleate Boiling DNBOPM DNB Overpower Margin DNBR DNB Ratio EPOL COLSS DNBR Overall Uncertainty Factor FLAIR CE Neutronics Simulator Fo 3-Dimensional Peaking Factor Fxy Planar Radial Peaking Factor HID-1 High Impact Design Spacer Grid (Type 1)

LCO Limiting Condition for Operation LHR Linear Heat Rate LPD Local Power Density LSSS Limiting Safety System Settings NRC Nuclear Regulatory Commission pdf Probability Density Function P01 Power Operating Limit PVNGS Palo Verde Nuclear Generating Station i

RCS Reactor Coolant System RPS Reactor Protection System RSF Rod Shadowing Factor SAM Shape Annealing Matrix SCU Statistical Combination of Uncertainties UNCERT COLSS LHR Uncertainty Factor (vi)

l l

1.0 INTRODUCTION

1.1 Purpose The purpose of this report is to describe changes to the methodology for statistically combining uncertainties associated with the LCO and LSSS setpoints for CE's digital monitoring and l protection systems. These changes are designed to improve plant l operating performance and flexibility and reduce the incidence of

~

unnecessary reactor trips by reducing the overall uncertainty factors applied in the COLSS and CPCS. Rigorous, statistically justified methods are used to establish the resultant uncertainty factors. The Core Operating Limit Supervisory System (COLSS) aids the operator in monitoring the Limiting Conditions for Operation (LCO) based on DNBR margin, Linear Heat Rate (LHR) margin, Axial Shape Index (ASI) and core power. The Core Protection Calculator System (CPCS) within the Reactor Protection System (RPS) initiates the reactor trips based, o3 low DNBR and high Local Power Density (LPD). OveraT1 uncertainty factors are

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determined and applied for both .the COLSS and CPCS such that the COLSS Power Operating Limits (POL) and the CPCS DNBR and LPD calculations are conservative to at least a 95/95 probability / confidence level. The Modified Statistical I Combination of Uncertainties Program resulting from the methodology changes described in this report has been developed in such a way that this level of conservatism is maintained.

1.2 Background

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1.1.1 Protection and Monitoring Systems l

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The functions and interactions of the protection and monitoring systems, LCO's and LSSS's, and COLSS and CPCS are described in previous PVNGS SCU reports such as References 1 and 2 and in current COLSS and CPCS Reports such as (1)

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References 3, 4, and 5. The changes to the Statistical Combination of Uncertainties (SCU) methodology described in this report do not impact the functions of these systems.

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, 1.2.2 Current SCU Program 1

• I References 6, 7, and 8 are the latest references for the currently approved SCU methodology. The methods documented in these SONGS references are similar to those used for System 80 (i.e. PVNGS Cycle 1) as documented in~ References 1, 2 and 11. As part of the CPC Improvement Program, several modifications were made to simplify the SCO analysis process. These modifications are documented in Reference 9.

NRC approval of the CIP related modifications was provided in Reference 10. The changes to the SCU methodology for the Modified SCU program are presented in this report based on the current SCU program described in these references.

The uncertainties involved-in the SCU methodology are divided into two categories. The first category, referred to as " system parameter" uncertainties, includes engineering factors, CHF correlation uncertainties and TORC code modeling uncertainties. The uncertainties in this group are statistically comoined to generate a DNBR probability density function (pdf). The 95/95 i probability / confidence level tolerance limit of this function has been used as the DNBR limit in COLSS and CPCS l thus accounting for the uncertainties in this category. l l

The second category, referred to as " state parameter" uncertainties, includes measured state parameter, COLSS and

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CPC algorithm, radial peaking factor measurement, simulator model, computer processing. and startup measurement uncertainties. The state parameter, algorithm and startup (2)

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_ . - - _ -m _ . - - - - - _ - - -

measurement uncertainties are stocha:Scically simulated to generate a- state parameter pdf. The 95/95 probability / confidence level of this- function is then root-sum-squared with the other uncertainties to determine the CPC and COLSS overall uncertainty factors, hence accounting for the uncertainties in this group. The uncertainty analysis which determines these overall uncertainty factors in the heretofore approved SCU program is illustrated in Figure 1-1.

Even though uncertainties within each part are combined

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statistically and a 95/95 probability / confidence level is generated for each group, the resultant uncertainties of the two groups are effectively combined in a deterministic manner due to separate application in the DNBR limit'and the overall uncertainty factors. Tables 1-1 and 1-2 list the uncertainties included in the system parameter and the state parameter categories, respectively. These uncertainties are defined and described further in References 6, 7, and 8.

In the current SCU methodology, power measurement uncertainties are applied separately from the system. and state parameter uncertainty factors. COLS$ nonnally uses secondary calorimetric power as the ' standard and therefore i the power measurement uncertainty for COLSS consists of the j secondary calorimetric uncertainty. The CPC neutron flux power measurement uncertainty factor is calculated by a deterministic combination- of the secondary calorimetric uncertainty, a calibration allowance, and the neutron fiux j

' power synthesis uncertainty. The CPC thermal- power measurement uncertainty factor is calculated by a deterministic combination of. the secondary calorimetric  !

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uncertainty, a calibration allowance, and a thermal power i transient offset, if needed.

j Figure 1-2 is a schematic- of what will henceforth be I referred to as the " current SCU" program, j I

I (3)-

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'1.3 Modified SCU Program This document describes the changes to the current SCU program designed to improve plant operating performance and flexibility and reduce the incidence of unnecessary reactor trips by reducing l excess conservatism in the DNBR overall uncertainty factors for

- COLSS and CPCS. The reduction in overall uncertainty factors j results primarily from[ l

] In addition, minor changes have been made in the statistical {

treatment of several components and the methodology has been developed so that the overall uncertainty factors can be l calculated and applied in discrete regions of core burnup, power, i 1

and axial shape index (ASI). The changes made to the SCU program  !

I are the following:

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2.

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5. Develop the methodology for determining and implementing Burnup, ASI, and Power dependent uncertainty factors in l COLSS and CPCS.

(4)

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These changes are d'escribed in more detail' in Section 2.0.

'The 500 program with all these modifications will. henceforth be referred to as the " Modified SCU" program. Figure 1-3 provides a schematic of the Modified SCU program.

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. 1.4 Summary of Results 1 l

The methodology of the Modified SCU program will generate overall i uncertainty factors such that: the. COLSS- Power Operating Limit l (POL) and CPCS DNBR and LPD calculations are conservative to at least a 95/95 probability / confidence level. The changes to the SCU methodology described in this report do not impact-either the manner in which COLSS aids the operator in maintaining operating margin to limits on linear heat' rate (LHR) and DNB or the manner I

in which the CPCS responds to transients and provides the low DNBR and high LPD trips. Therefore, the changes do not impact ]

transient analysis assumptions or results and' do not involve changes to Technical Specifications.

In Section 3.0, the Modified U program methodology. has been l applied to PVNGS using typical models and input data and results in DNBR overall uncertainty factors of for. COLSS and for CPCS.

W (5) 1 _ _ . - __ _-_- _ - _ _

_ . ,n- . ..

a Table 1-1 I

Uncertainties included in the System parameter SCO 1

Core inlet flow distribution II)

Engineering factor on enthalpy rise Systematic fuel rod pitch

. Systematic fuel clad 0.D. ) 1 Engineering factor on heat flux-CE-1 CHF correlation (Including cross validation uncertainty)

TORC code uncertainty Fuel rod bcw penalty I2)

HID-1 grid penalty _(2) l '

'l

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-1 (1) Core inlet flow distribution uncertainty  ;

for System'80 plants (2) -

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e (6)

L _-___ _ _ _____-_____ __- _ _ __ - -_-_ - _ _ _ - - _ __ .- -

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Table 1-2 l

General Categories of Uncertainties _ Included in State Parameter SCU i

Measured State Parameter Uncertainties

- Algorithm Uncertainties Startup Measurement Uncertainties l

1 l

Radial Peaking Factor Measurement Uncertainty Computer Processing Uncertainties 4

Simulator Model Uncertainties Rod Bow Penalty on Fxy 1

l (7)

L__-._____________.___.__.___________________.__._______________________ . _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ __

FIGURE 1 1 COLSS AND CPCS UNCERTAINTY ANALYSIS

'~ FOR CURRENT SCU _

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2.0 METHODS u

2.1 INTRODUCTION

l The current SCU program is described in References 6, 7, and 8 with CPC Improvement Program modifications described in Reference

9. The following sections describe ~ the changes made to the SCU

~

methodology in the Modified SCU program. Section 3.0 will provide a typical ~ DNBR overall uncertainty factor calculation using the Modified SCU program.

The changes to the SCU methodology primarily impact the' treatment of system parameters, secondary calorimetric power measurement, and neutron flux power synthesis uncertainties as described _ in Sections 2.2, 2.3, and 2.4, respectively. Section 2.5 presents other minor methodology changes.

2.2 SYSTEM PARAMETER SCU METHODOLOGY The uncertainties considered in the system parameter SCU include engineering factors, CHF correlation uncertainties and TORC code modeling uncertainties. In the current system parameter SCO analysis, described in Reference 6, these uncertainties are combined statistically to arrive at the DNBR limit. The Modified SCU methodology [

] Thus the DNBR overall uncertaintyfactorsforCOLSSandCPC[

0 (11)'

E

The individual uncertainties that are combined in the system parameter SCU are as follows:

a) Core inlet flow distribution II) b) Engineering factor on enthalpy rise c) Systematic fuel rod pitch d) Systematic fuel rod diameter e) Engineering factor on heat flux

. f) CE-1 CHF correlation g) CE-1 CHF correlation cross validation penalty (5%

increase in CHF correlation standard deviation) h) T-H code uncertainty penalty (5%, equal to two standard deviations)

These uncertainties are statistically combined to yield the DNBR

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probability density function (pdf).

In the current SCU analysis the 95/95 probability / confidence limit of this DNBR odf is deterministically combined with the fuel rod bow and the HID-1 grid penalties to determine the minimum DNBR limit to be applied in COLSS and CPC. This DNBR limit is then usec in the state parameter SCU stochastic simulation to determine the COLSS and CPCS DNBR overall uncertainty factors. This limit is also used in the on-line COLSS DNBR power operating limit calculation and as the CPCS DNBR trip setpoint.

In the Modified SCU methodology, the system parameter uncertainties are combined in the same way to determine the DNBR

. odf. However, (1)

Coreinletflowdistributionuncertainty{

for System 80 plants.

(12)

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i This modification to the SCU program is consistent with' '

statistical methods approved in the current SCO program. -)

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are chosen such that the COLSS DNBR POL and CPCS ONBR -

calculations are conservative at a 95/95 probabilit'y/ confidence l l-1evel.

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I 2.3 SECONDARY CALORIMETRIC POWER MEASUREMENT UNCERTAINTY METHODOLOGY i

Both COLSS and CPC use Secondary Calorimetric power as a measure .

of true core power for their LHR/LPD and DNBR' calculations. The calculation of Secondary Calorimetric power has an uncertainty associated with it. Currently, this uncertainty is calculated statistically as described in Reference 7 and applied deterministically in both COLSS and CPC. The Modified SCU methodology will apply this uncertainty ,

The Secondary Calorimetric power measurement uncertainty (ECAL) is core power dependent. Figure 2-1 shows a typical example of the uncertainty as a functicn of - power. ,

In ' the current. SCU ,

program, this uncertainty is applied as , ,

directly on the core power used in' the COLSS and on the thermal and neutron flux power used -in CPC. This uncertainty is implemented [inbothCOLSSandCPC.

(13)

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In the Modified SCU methodology, the Secondary Calorimetric power l

measurement uncertainty will be represented by[

The DNBR overall uncertainty analysis l will statistically [-

} The metnod of application of this

. uncertainty will remain deterministic, unchanged from the current methodology,( ..

. )

The Modified SCU approach is consistent with statistical methods approved in the current SCU program. Application of this uncertainty [ ]willcontinue l l to assure conservative DNBR POL calculations by COLSS and DNBR calculations by CPCS to at least a 95/95 probability / confidence level.

"3:. /

2.4 CPC NEUTRON FLUX POWER SYNTHESIS UNCERTAINTY METHODOLOGY The CPC Neutron Flux Power calculation based on ex-core detector signals includes a neutron flux power measurement uncertainty.

One component of this uncertainty is the power synthesis uncertainty. The current SCU method for determining and applying this uncertainty is described in Reference 7. The Modified SCU methodology will[.

)

In the current SCU analysis, a pdf of the power synthesis uncertainty is produced at the same time that the DNBR l uncertainty factor is determined. The 95/95 probability / confidence tolerance limit of the pdf is applied [

in the CPC Neutron Flux Power calculation.

(14)

In the Modified SCU analysis, the power synthesis uncertainty will be applied [

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The Modified SCU program approach is consistent with statistical methods.aoproved in the current SCU program. Application of this uncertainty , ]willcontinue to assure a conservative DNBR calculation by CPCS at a 95/95

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probability / confidence level.

. 2.5 OTHER MODIFICATIONS TO SCU METHODOLOGY The Modified SCU methodology includes several minor changes to the techniques of determining and applying uncertainty components. These chat ges, described in the following section, are consistent with statistical methods approved in the current SCU program and retain conservatism in the resultant uncertainty factors to at least a 95/95 probability / confidence level.

2.5.1 RADIAL PEAKING FACTOR MEASUREMENT UNCERTAINTY APPLICATION Both COLSS and CPC use Radial Peaking factors -(Fxy's) that are verified, and adjusted if pe:essary, during startup testing. The Fxy measurement which is used for this verification has an uncertainty associated with it.

In the current SCU analysis, the Fxy measurement uncertainty is combined with other uncertainty components [

O (15)

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In the Modified SCU methodology the Fxy uncertainty will be i

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Fxy uncertainty will be ,

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This modification involves only a ' .l change in the statistical combination technique for this '

particular uncertainty component.  ;

2.5.2- APPLICATION OF UNCERTAINTY FACTORS AS A FUNCTION OF BURNUp, ASI, AND POWER .ll l

The COLSS and CpC overall uncertainty factors calculated in the SCU analysis typically vary as a function of power level, cycle l i

burnup, and Axial Shape Index (ASI). In the current SCU methodology, limiting values of these uncertainty factors are chosen and applied for all conditions. j The Modified SCU methodology will allow calculation and ,

application of these uncertainty factors over several burnup,  ;

i power, and ASI ranges. Choice of parameters and ranges will be made on a cycle-by-cycle basis in order to optimize the  ;

uncertainty factors for nominal full power operation throughout

-l the cycle, while retaining conservatism at a 95/95  !

probability / confidence level for all conditions.

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1 FIGURE 2-1 :1 SECONDARY CALORIMETRIC POWER MEASUREMENT UNCERTAINTY ,

i (SAMPLE PVNGS VALUES) i 1

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l 3.0 TYPICAL OVERALL UNCERTAINTY FACTOR CALCULATION l

3.1 INTRODUCTION

, The changes to the SCU Program described in Section 2.0 result in l l

a Modified SCU methodology which can be applied to all C-E plants with digital monitoring and protection systems. The Modified SCO Program will be initially applied to PVNGS Unit 1 Cycle 2. )

Therefore, a calculation of COLSS and CPC DNBR overall uncertainty f actors is presented here using typical PVNGS models j and input data. This calculation will illustrate the application l of the Modified SCU methodology and its results.

3.2 DNBR odf The System Parameter SCU methods used to determine the DNBR limit and pdf remain unchanged from that described in Reference 6. The uncertainties combined to derive this pdf are listed in Table 3-1 )

with typical values for PVNGS. The resultant pdf is shown in Figure 3-1. ..

As in the current SCU methodology, the DNBR limit for COLSS, CPC, and transient analyses is defined by the following equation:

DNBR limit = TL

• PB0W + PHID where  ;

TL = 95/95 probability / confidence tolerance limit of DNBR pdf.

PBOW = Rod Bow Penalty PHID = HID-1 Grid Penalty l

l (18)

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.]the DNBR . limit  !

1 generated by this method is used in the on-line COLSS and CPC and i in the transient analyses. )

l The tolerance limit for the pdf shown in Figure 3-1 is 1.205. -]

Combining this 'with the rod bow penalty (1.75%) and the HID-1 grid penalty (0.01) yields a DNBR limit of 1.237.

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3.3 SECONDARY CALORIMETRIC p0WER MEASUREMENT UNCERTAINTY pdf l

The secondary calorimetric _ power measurement uncertainty is l calculated from the uncertainties of the various measured l parameters used to calculate the ~ secondary calorimetric power.

l These components are listed in Table 3-2 with typical values foi PVNGS

}

3.4 COLSS DNBR OVERALL UNCERTAINTY FACTOR CALCULATION i

l The COLSS DNBR overall uncertainty analysis process ~using l Modified SCU is illustrated in Figure 3-2. I

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As in the current SCU Program (Reference 8), ,

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l Table 3-3 lists the state parameter measurement uncertainty l components [ ]in the COLSS overall uncertainty analysis,,

including typical ranges and uncertainty values' for PVNGS. The-uncertainty components [ }are listed with typical .j l PVNGS values in Table 3-4 and- the remaining uncertainty components [

are presented in Table 3-5.

The COLSS DNBR overall uncertainty analysis using the typical 1

PVNGS input values results in a DNBR overall uncertainty factor ]

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3.5 CPCS DNBR OVERALL UNCERTAINTY FACTOR CALCULATION I

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, The CPC DNBR overall uncertainty analysis process is illustrated in Figure 3-3.

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As in the current SCU program (Reference 7),[ ,

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1 Table 3-6 lists the state parameter measurement uncertainty components.[ ]in the CPC overall uncertainty analysis, including typical ranges and uncertainty values for PVNGS. The uncertaintycomponents[ ]arelistedwithtypical PVNGS values in Table 3-7 and the' remaining- uncertainty components [ }arepresentedinTable3-8.

The CPC DNBR overall uncertainty analysis using the typical PVNGS

, input values results in a DNBR overall uncertainty factor of f  :

(E1)

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.j Table 3-1 Components Combined in the DNBR pdf

\

. Std. Deviation at parameter Mean 95% Confidence 1

4

. - . J Inlet flow distribution Enthalpy rise-factor Systematic pitch (in) '

Systematic clad OD (in)

Aeat flux factor I 1

CE-1 CHF correlation .q TORC code uncertainty -

]

DNBR pdf [ ]

l Inlet flow distribution uncertainty [ -]for System 80 plants.

• • Includes 5% cross-validation uncertainty

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1 Table 3-2

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l Secondary Calorimetric Power Measurement Uncertainty Components 1

STD. Deviation Parameters Units at 95% Confidence

• Feedwater Flow (delta P transmitter) IN. of H 2O Feedwater Temperature F Steam Flow (delta P transmitter) IN. of H 2O Blowdown Mass Flow Rate KPPH Steam Quality -

Secondary Pressure PSIA l

. l W4 l

i (23)

Table 3-3 COLSS State Parameter Ranges and Measurement Uncertainties Measurement Parameters Unit Ranges Uncertainty Core Inlet Coolant ('F)

Temperature Primary Coolant (psia)

Pressure 6

Primary Coolant (10 lbm/hr. ft 2)

Mass Flow Incore Detector Signal (%)

CEA Position (inches)

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I Table 3-4 UncertaintyComponentf i

- l.in COLSS DNBR Uncertainty Analysis Std. Deviation at Parameter Mean 95% confidence I

l System Parameter Uncertainty DNBR pdf 1

I Radial Peaking Factor Measurement Uncertainty

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Secondary Calorimetric Power Measurement Uncertainty

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Table 3-5 {

'l Uncertainty Components"

}toDetermine COLSS DNBR Overall Uncertainty Factors i

Parameter Value Fuel Rod Bow Penalty on Fxy .i 1

Computer Processing Uncertainty

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Simulator.Model Uncertainty

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.r Ta'ble 3-6 CPCS State Parameter Ranges and Uncertainties

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1 Measurement Parameters Unit Ranges Uncertainty Core Inlet _ _

Coolant Temperature ('F)

Primary Coolant Pressure (psia)

Primary Coolant 6 -'

Mass Flow (10 lbm/br-ft2) '

Ex-core Detector -'

Signals (% power)

CEA Positions (inches) -

Startup Measurement Uncertainties-

' ~

- Rod Shadowing Factor

- Shape Annealing Matrix **

- Boundary Point Power Correlation Coefficient

• • Assumed Excore Noise Level During Test (27) t

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Table 3-7 4

l Uncertainty Component' in CPC ONBR

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pvera11 Unce'rtainty Analysis 1 .

Std. Deviation of  ;

Parameter Mean 95% Confidence.

l System Parameter Uncertainty DNBR pdf Radial Peaking Factor Measurement j Uncertainty Secondary Calorimetric Power Measurement Uncertainty l Neutron Flux Power ..

Synthesis Uncertainty

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Table 3-8' i

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Uncertainty Components lto Determine

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CPC DNBR Over'a11 Uncertainty Factors - 'I Parameter Value ,

- _ .j Fuel Rod Bow Penalty on Fxy j Computer Processing Uncertainty Simulator Model Uncertainty -

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4.0 CONCLUSION

This report describes changes to the current SCU Program which are designed to improve plant operating performance and {

flexibility and reduce unnecessary trips. These changes result in a Modified SCU Program which is applicable.to all C-E plants with digital monitoring and protection systems. The overall j uncertainty factors determined using the Modified SCU program J continue to ensure that the COLSS POL calculations and the CPCS DNBR and LPD calculations will be conservative to at least a 95%

probability and 95% confidence level. The initial application of the Modified SCO program is planned for PVNGS Unit 1 Cycle. 2. '

The Modified SCU program methodology has been applied to PVNGS using . typical models and input data and results in DNBR overall

~ ~ ~

uncertainty factors of for COLSS and' for CPCS.

4

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(33)

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1 1

5.0 REFERENCES

I l

1 " Statistical Combination.of Uncertainties Part II",

Enclosure P to LD-83-010, January,1983.  !.

2 " Statistical Combination of Uncertainties'Part III",

Enclosure 2-P to LD-83-010, Rev. 01, August, 1983.  ;

1 1 l, 1 l.- :

3 CEN-312-P, Rev 01-P " Overview Description of the Core -

i 1

Operating Limit Supervisory System (COLSS)", November,- j i

1986. a 4- CEN-304-P, Rev 01-P, " Functional Design Requirements for a

)

Control Element Assembly. Calculator"., May,1986.

5 CEN-305-P, Rev 01-P " Functional Design Requirements for 'a Core Protector Calculator", May, 1986, 6 " Statistical Combination of Uncertainties Part I",

CEN-283(S)-P, October, 1984/

I 7 " Statistical Combination-of Uncertainties Part II".

CEN-283(S)-P, October, 1984.

1 8 " Statistical Combination of Uncertainties Part !!!",

CEN-283(S)-P, October, 1984. ,

9 " Statistical Combination of Uncertainties .for Waterford-3", 'j CEN-343 (C)-P, October, 1986.

10 Letter from J. H. Wilson (NRC) to J. G. Dewease (Louisiana <

Power and Light Company), "Raload Analysis Report for

^

Cycle 2 at Waterford 3", Docket.50-382, January, 1987.

11 " Statistical Combination of Uncertainties Part I",

Enclosure 1-P to LD-83-010, January, 1983.

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