2CAN058113, Forwards Core Protection Calculator Addressable Constant Determination Methodology, in Response to 810505 Request.Comprehensive Document Suitable for Referencing in Tech Spec Bases Will Be Sent by 810817
| ML20004B683 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 05/26/1981 |
| From: | Trimble D ARKANSAS POWER & LIGHT CO. |
| To: | Clark R Office of Nuclear Reactor Regulation |
| References | |
| 2CAN058113, 2CAN58113, NUDOCS 8105290289 | |
| Download: ML20004B683 (12) | |
Text
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ARKANSAS POWER & LIGHT COMPANY P. O. Box 551 Little Rock, AR 72203 May 26, 1981
- CAN058113 Director of Nuclear Reactor Regulation ATTN:
Mr. Robert A. Clark, Chief Operating Reactors Branch 3 Division cf Licensing U.S. Nuclear Regulatory Commission
'Ja shington, D. C.
20555
SUBJECT:
Arkansas Nuclear One - Unit 2 Docket No. 50-368 License No. NPF-6 NRC Request for Information on CPC Addressable Constant Determinations (File: 2-1510 1
Gentlemen:
Your letter of May 5,1981, requested that AP&L provide a document which describes how CPC addressable constants are determined which is suitable for referencing in the bases to the ANO-2 Technical Specifications.
In a telephone conference between AP&L and NRC on May 14, 1981, this request was discussed and our understanding of the agreement reached during that conversation is provided in the following paragraph.
AP&L agreed to provide to NRC a description of how the values are determined for those addressable constants which we plan to modify as a result of Technical Specification requirements or reload testing requirements.
In addition, a description of the purpose of other addressable constants which AP&L does not anticipate modifying will be provided. This information was agreed to be provided by letter to NRC by May 26, 1981 and is enclosed as an enclosure to this letter.
81052'90#i9
[
VEveE A M: DOLE SOUTH UTIUT ES SYSTEV,
Page 2 In addition, AP&L agreed to provide a more comprehensive document, suitsble for referencing in the Technical Specification bases, which explains the methodology for determination of all addressable constant values.
It was agreed that 60 to 90 days was acceptable for submittal of this CPC address-able constant methodology report. Therefore, we will submit this document to NRC by August 17, 1981.
Very truly yours, b
[.
David C. Trimble Manager, Licensing DCT:THC:sbp Enclosure cc: ANO-DCC i
I L
ANO-2 CORE PROTECTION CALCULATOR ADDRESSABLE CONSTAhT DETERMINATION METHODOLOGY
1.0 DESCRIPTION
The Core Protection Calculator System includes a number of addressable constants which are provided to:
a.
Allow periodic calibration as required by the Technical Specifications or reload analysis report.
b.
Adjust the CEAC inputs used by the CPCS based on CEAC/RSPT operability.
c.
Apply penalty factors, allowances, etc. based on measured plant conditions / parameters to ensure CPC calculational conservatism.
d.
Account for ceasurement and modeling uncertainties.
A list of CPC adderessable constants is attached (see Table 1.0-1).
This list separately shows Type I addressable constants and Type II addressable constants.
Type I constants are expected to change frequently during plant operation and values are entered only via the CPC Operator's module.
Type II constants are not expected to change frequently and are normally loaded from a disk storage unit.
This mechanism has been implemented in order to reduce the probability of re-entry error upon CPC software reload.
[
l I
l' 1
TABLE 1.0-1 CORE PROTECTION CALCULATOR ADDRESSABLE CONSTANTS I.
TYPE I ADDRESSABLE CONSTANTS POINT ID PROGRAM NUMBER LABEL DESCRIPTION 60 FCl Core coolant mass flow rate calibration constant 61 FC2 Core coolant mass flow rate calibration constant i
62 CEANOP CEAC/RSPT inoperable flag 63 TR Azimuthal tilt allowance 64 TPC Tnereal power calibration constant 65 ECAL Neutron flux power calibration constant 66 DNBRPT DNBR pretrip setpoint 67 LPDPT Local power density pretrip setpoint i
II.
TYPE II ADDRESSABLE CONSTANTS POINT ID PROGRAM l
NUMBER LABEL DESCRIPTION 68 BERR0 Thermal power uncertainty bias I
69 BERR1 Power uncertainty factor used in DNBR calculation I
70 BERR2 Power uncertainty bias used in DNBR ca'1culation i
71 BERR3 Power uncertainty factor used in local power density calculation 72 BERR4 Power uncertainty bias used in local power density calculation 73 EOL End of life flag 74 ARM 1 Multiplier for planar radial peaking factor 1
75 ARM 2 Multiplier for planar radial peaking factor l
j 76 ARM 3 Multiplier for planar radial peaking factor 77 ARM 4 Multiplier for planar radial peaking factor 78 ARMS Multiplier for planar radial peaking factor t
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TABLE 1.0-1 CORE PROTECTION CALCULATOR ADDRESSABLE CONSTANTS (Continued)
POINT ID PROGRAM NUMBER LABEL DESCRIPTION 79 ARM 6 Multiplier for planar radial peaking factor 80 ARM 7 Multiplier for planar radial peaking factor 81 SC11 Shape annealing correction factor 82 SC12 Shape annealing correction factor 1
83 SCl3 Shape annealing correction factor 84 SC21 Shape annealing correction factor 85 SC22 Shape annealing correction factor 86 SC23 Shape annealing correctica factor 4
87 SC31 Shape annealing correction factor 88 SC32 Shape annealing correctica factor 89 SC33 Shape annealing correction factor 90 PFMLTD DNBR penalty factor correction multiplier i
91 PFMLTL LPD penalty factor correction multiplier 92 ASM2 Multiplier for CEA shadowing factor 93 ASM3 Multiplier for CEA shadowing factor 94 ASM4 Multiplier for CEA shadowing factor 95 ASMS Multiplier for CEA shadowing factor 96 ASM6 Multiplier for CEA shadowing factor l
97 ASM7 Multiplier for CEA shadowing factor i
I 98 CORR 1 Temperature shadowing correction factor multiplier 99 BPPCC1 Boundary point power correlation coefficient 100 BPPCC2 Boundary point power correlation coefficient 101 BPPCC3 Boundary point power correlation coefficient i
102 BPPCC4 Boundary point power correlation coefficient 3
l t
2.0 SCOPE This document describes the methodology used by ANO personnel to determine the values of those addressable constants which are changed I
due to Technical Specification or reload analysis report requirements for calibration or adjustment of CPC indications. The determination of base values of certain CPC addressable constants by the reload de-signer is not described in this document.
3.0 METHODOLOGY 3.1 Core Coolant Mass Flowrate Calibration Constants (FCl and FC2)
The CPC software supplies the constants FC1 and FC2 in the following manner:
Madj = M x FC1 + FC2 where M = the CPC measured RCS mass flow rate Madj = adjusted (calibrated) RCS mass flow rate The RCS flow rate is determined by calorimetric calculations.
The CPC flow rate is observed, recorded and compared to the calori-metric value.
If adjustment is required, the adjusted CPC flowrate may be accomplished by changing the value of addressable constant FC1, FC2 or both.
ANO-2 procedures use the following method:
=
--FCI (old)
FCl (new) x M (Calorimetric)
MCPC FCI (old)
FCl (new) x M (Calorimetric) -0.0025
=
MCPC Where: MCPC = the CPC measured RCS flow rate M (Calorimetric) = the RCS flowrate detercined by calorimetric methods.
The bias of 0.0025 is applied to accomcdate possible in-l instrument drift during calorimetric measurements.
FC2 (new)
FC2 (old)
= 0.0
=
3.2 CEAC/RSPT inoperable Flag (CEANOP)
ANO-2 operating procedures specify that the value of CEANOP shall l
be set as follows:
4 L
CEANOP
=-0 if both CEAC/RSPT channels are OPERABLE CEANOP = 1 if CEAC/RSPT channel #1 is not OPERABLE CEANOP = 2 If CEAC/ESPT channel #2 is not OPERABLE CEANOP = 3 if both CEAC/RSPT channels are not OPERABLE 3.3 Azimuthal Tilt Allowance (Tr)
In accordance with the Technical Specifications, ANO-2 operating procedures require that the azimuthal tilt allowance value used in the CFCS must be maintained at a value higher than the azimuthal tilt determined by calculations using incore d+tectors or if the incore detector system is not OPERABLE by using the excore detectors.
I For example:
If the azimuthal tilt magnitude is determined to be 0.025 (2.5%),
then the tilt allowance value (TR) in the CPC cust be maintained at greater than 1.025.
3.4 Thermal Power Calibration Constant (TPC) and Neutrcn Flux Power Calibration Constant (KCAL)
ANO-2 procedures requic2 periodic calibration of the CPC thermal power and the CPC neutron flux power values in accordance with the Technical Specifications.
The method used is as follows:
1.
Determine the current NSSS calorimetric power level (NCP) 2.
Compare the current CPC thermal power (BDT) and CPC neutron flux power (PHICAL) values to the caloritetric value.
3.
If adjustment is required, new addressable constant aiues are determined as follows:
= -"CP(%) x TPC (old)
TPC (new)
BDT
(%)
NCP(%) x KCAL (old)
KCAL (new)
=
PHICAL (%)
3.5 DNBR and Iocal Power Det ity Pretrip Setpoints (DNBRPT and LPDPT)
The value of the addressable constants DNBRPT and LPDPT are adjusted to provide pre-trip alarms prior to the respective DNER and LPD trips.
The values are determined by operating experience to provide early operator notification of potential reactor trip events.
5
3.6 Power Uncertainty Bias and Factor Constants (BERRO, BERR1, BERR2, BERR3 and BERR4)
The values of these addressable constants are determined by the re-load designer based upon the measurment and modeling uncertainties associated with the specific plant instrumentation, core design and modeling methods. During routine cycle operation of ANO-2 these values sre not expected to change.*
During cycle 2, the value of BERR1 will temporarily be in-creased to account for additional rod bow peaalties pending NRC approval of C-E's rod bow Topical Repert.
3.7 End of Life Flag (EOL)
The EOL flag is provided to cause the CPC to select a different boundary point power formulation.
If the axial flux shape changes from chopped cosine to saddle-shaped, the EOL flag may be changed.
During ANO-2 cycle 1, this change was not found to be necessary and may not be necessary in subsequent cycles.
If the alternate boundary point power formulation were to be used the EOL flag is set equal te one. Normally the value of ECL is zero.
3.8 Multipliers for Planar Radial Peaking Factors i
(ARM 1, ARM 2, ARM 3, ARM 4, ARM 5, ARM 6 and ARM 7)
With the reactor at steady state, equilibrium xenon conditions, the power distribution is measured using incore detectors. The measured planar radial peaking factor, Fxy, is determined from this data and is compared to the appropriate CPC planar radial peaking factor for the CEA configuration applicable for the measurement condition.
If the CPC peaking factor is not greater than or equal to the measured peaking factor then the appropriate ARMx addressable constant (see Table 3.8-1) is adjusted.
i l
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6
TABLE 3.8-1 CPC Fxy Multiplier CEA Configuration ARM 1 All rods out ARM 2 CEA Group P inserted ARM 3 CEA Group 6 inserted ARM 4 CEA Groups 6, P inserted ARM 5 CEA Groups 6, 5 inserted ARM 6 CEA Groups 6, 5, P inserted ARM 7 Any other configuration If adjusteen is required then the appropriate cultiplier ARMx is determined as follows:
Fxy (measured)
ARMx =
Fxy (CPC) x f The factor f is dependent on core burnup and CEA configuratica and assures that the maximum peaking facter will not exceed the values used by the CPC at any time during the cycle.
3.9 Shape Annealing Correction Factors (SC11, SC12, SC13, SC21, SC22, SC23, SC31, SC32 and SC33)
The Shape Annealing Correction Factors (SACF) are determined from a least squares fit of the measured excore detector readings and corresponding axial power distribution determined from incore detectors signals.
Since these values must be re-presentative for rodded and unrodded cores throughout life, it is desirable to use as wide a range of core axial shapes as are avail-able to establish their values. This is done by initiating an axial xenon oscillation. Data is periodically gathered during the oscillations so that the data will be representative of as wide a range of axial shapes as possible.
Incore, excore and related data is recorded.
This data is input to the CECOR incore analysis code which relates the incore detector signals to power distribution and summarizes the necessary power distribution _ and excore detector data in a form and format which can be easily input to programs used to perform the least squares fitting.
The output from CECOR includes:
a) the three excore detector fractional responses (Di) for each CPC channel.
b) the core peripheral power fractions for the upper, middle, and lower third of the core (Pi) as measured from incore detectors.
c) the core average power fractions for the upper, middle', and lower third of the core, and d) the upper and lower core boundary average power.
7
The measured values of D and P are used to calculate the SACF 4
g 4
values for each of the f6ur CPC channels.
"< >" represents the i
mean value withdrawal of the control rods.
The shape annealing matrix is:
SC SC SC i
11 12 33 SE =
SC SC 3U 21 22 23 SC SC SC i
33 32 33 Where:
SC
<D D>
<D D>
<D D
Di y>
{
gy y
y y 2 y 3 SC
=
<D D>
<D D>
<D D
X
'P D
12 y 2 3 2 2 3 g 2
<D D
<D D 's
<D D
<I D#
j SCf3_
r y 3 2 3 3 3 i 3 for i = 1,2,3 i
The measured shape annealing matrix values shall egree acceptably with the installed values in the CPC or the addressable instants 4
updated to the measured values.
3.10 DNBR and LPD Penalty Factor Correction Multiplier (PFMLTD and PFMLTL)
These addressable multipliers are applied to the CIA deviation i
penalty factors on DNBR and LPD respectively. The value to be used is specified by the reload designer and changes during the cycle j
are not anticipated.
i j
3.11 Multiplier for CEA shadowing Factors (ASM2, ASM3, ASM4, ASMS, ASM6 and ASM7) l The CEA shadowing Factors are verified by testing following reload.
At steady state power, equilibrium xenon conditions, the response of the summed excore detector signals (Di) for each CPC is compared to the NSSS calorimetric power level (BSCAL) for various CEA con-figurations.
The CEA Shadowing Factor for a specified CEA confiyuration is:
i 3
BSCAL (unrodded) x I Di (rodded) i=1 Fx =
3 BSCAL (rodded) xI Di (unrodded) i=1 for PLCEAS (Group P) not inserted 8
4 BSCAL (unrodded) x D2 (r dded)
BSCAL (rodded) xD2 (unr dded) for PLCEAS (Group P) inserted The measured Fx value for a given CEA configuration must agree acceptably with the tabulated CEA shadowing factors used in the CPC or a correction will be calculated and applied via the addressable cultipliers ASM2 through ASM7. The appropriate correction factor is selected from Table 3.11-1 based on the CEA configuration.
TABLE 3.11-1 CPC CEA Shadowing Multiplier CEA Configuration ASM2 CEA Group P inserted ASM3 CEA Group 6 inserted ASM4 CEA Groups 6 and P inserted ASM5 CEA Groups 6 and 5 i.serted ASM6 CEA Groups 6, 5 and ? inserted ASM7 all other configurations The magnitude of the correction is determined such that all values of Fx for conditions affected by a single multiplier are acceptable.
Fx (measured)
ASMx
=
Fx (CPC) 3.12 Temperature Shadowing Correction Factor Multiplier (CORRI)
The slope of the coolant temperature shadowing factor has been made addressable, whereas in cycle 1 it was in the non-addressable data base.
The value was determined during cycle 1 startup testing and is not reload dependent.
Consequently the value is not anticipated to require change. No testing to re-measure this parameter is planned.
3.13 Boundary Point Power Correlation Coefficients (BPPCC1, BPPCC2, BPPCC3 and B?PCC4)
The boundary point power correlation coefficients are determined from a least squares of the measured excore detector readings and corresponding axial power distribution determined from incore detectors signals.
Since these values cast be repre-sentative for rodded and unrodded cores throughout ~'.fe, it is desirable to use as wide a range of core axial chaps as are available to establish their values. This is done by initiating an axial xenon oscillation. Data is periodically gathereo during the oscillations so that the data will be representative of as wide a range of axial shapes as possible.
Incore, excore and related data is recorded. This data is input to the CECOR 9
incore analysis code which relates the incore detector signals to power distribution and summarizes the necessary power distribution and excore detector data in a form and format which can be easily input to programs used to perform the least squares fitting. The output from CECOR includes:
a)
The three excore detector fractional responses for each CPC, b)
The core peripheral power fractions for the upper, middle and lower third of the core, c)
The core average power fractions for the upper, middle and lower third of the core (P, Pm and P ) and u
t d)
The upper and lower core boundary average pcwer.
9(0) and P(L)
The BPPCC's are determined in a manner similar tc that used to determine the shape annealing matrix.
The values cf P,, T(0), P t and f(L) are obtained from CECOR and used to ccmpute clie BPPCC's by means of the following matrix equations:
-1 l
l BPFCC1
-
<F ?(0)> l u u u u B -<P 1 -<4(0)> I L_PPCC2__ m u J -1 PPCC3
-
BPPCC4l _ g g t t <P ) 1 -<4(L)> 7 1 where <n> represents g, I n over the data points taken .=1 The measured values of BPPCC1 through BPPCC4 must agree acceptably with the installed values in the CPC or the addressable constants updated to the measured valuer. 10