View source for SBK-L-14090, ANP-3243NP, Rev. 1, Seabrook Station, Unit 1, Fixed Incore Detector System Analysis Supplement to YAEC-1855PA, Licensing Report.

{{Adams
| number = ML14167A431
| issue date = 05/31/2014
| title = ANP-3243NP, Rev. 1, Seabrook Station, Unit 1, Fixed Incore Detector System Analysis Supplement to YAEC-1855PA, Licensing Report.
| author name = 
| author affiliation = AREVA, Inc
| addressee name = 
| addressee affiliation = NRC/NRR
| docket = 05000443
| license number = 
| contact person = 
| case reference number = LAR 13-05, SBK-L-14090
| document report number = ANP-3243NP, Rev. 1
| document type = Report, Miscellaneous
| page count = 86
}}

=Text=
{{#Wiki_filter:A AREVA Seabrook Station Unit I Fixed Incore Detector System Analysis Supplement to YAEC-1 855PA ANP-3243NP Revision 1 Licensing Report May 2014 AREVA Inc.(c) 2014 AREVA Inc.
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&#xa9; 2014 AREVA Inc.All Rights Reserved AREVA Inc.ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensinq Report Paqe i Nature of Changes Section(s)
Item or Page(s) Description and Justification 1 Abstract Discuss new uncertainty analysis Section 1.1 Section 5.3 Section 6.2 Section 7.0 Appendix B AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensinq Report Page ii Contents Paqe 1.0 TECHNICAL EVALULATIO N ................................................................................
1 1.1 Background 
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1 2.0 NEUTRO N CO NVERSIO N FACTO R ..............................................................
4 2.1 Current Licensing Basis ..........................................................................
4 2.2 Proposed M ethod .................................................................................
6 3.0 REPLACEM ENT DETECTO RS ........................................................................
8 3.1 General ...................................................................................................
8 3.2 Current Licensing Basis ..........................................................................
9 3.3 Proposed M odification 
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9 4.0 DEPLETIO N CO RRECTIO N FACTO R ..........................................................
11 4.1 Current Licensing Basis .......................................................................
11 4.2 Proposed M odification 
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11 5.0 CO M PARISO N O F FINC RESULTS ...............................................................
12 5.1 General .................................................................................................
12 5.2 Surveillance Param eter Com parisons ...................................................
12 5.3 Statistical Results ...............................................................................
26 6.0 UNCERTAINTY ANALYSIS ............................................................................
27 6.1 Current Licensing Basis .......................................................................
27 6.2 Proposed Uncertainty M odifications 
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30 6.2.1 Overview ....................................................................................
30 6.2.2 M ethodology 
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31 6.2.3 Uncertainty Calculation Details ..................................................
36 6.2.4 Uncertainty Calculation Results ................................................
38 6.2.5 Analysis of Significant Trends ..................................................
42 7.0 CO NCLUSIO NS ............................................................................................
46 

==8.0 REFERENCES==

...............................................................................................
47 APPENDIX A .................................................................................................................
48 APPENDIX B .................................................................................................................
71 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensinq Report Page iii List of Tables Table 1 Uncertainty Components and Confidence Multipliers from YAEC-18 5 5 P A .................................................. 
.......................................... 
..2 9 Table 2 95/95 Uncertainty Limits for FAH and FQ ............................
.......................... 43 Table B-1 Conservative Trend Slope of FAH UL(95/95) and FQ UL(95/95) for a Maximum of 8 Failed Detector Strings ..................................................
75 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page iv List of Figures Figure 1 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 1 ....................
14 Figure 2 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 2 ....................
14 Figure 3 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 3 ....................
15 Figure 4 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 4 ....................
15 Figure 5 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 5 ....................
16 Figure 6 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 6 ....................
16 Figure 7 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 7 ....................
17 Figure 8 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 8 ....................
17 Figure 9 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 1 ........ 18 Figure 10 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 2 ....... 18 Figure 11 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 3 ....... 19 Figure 12 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 4 ....... 19 Figure 13 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 5 ..........
20 Figure 14 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 6 ..........
20 Figure 15 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 7 ..........
21 Figure 16 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 8 ..........
21 Figure 17 Comparison of Axial Offset for Cycle 1 ...................................................
22 Figure 18 Comparison of Axial Offset for Cycle 2 ...................................................
22 Figure 19 Comparison of Axial Offset for Cycle 3 ...................................................
23 Figure 20 Comparison of Axial Offset for Cycle 4 ...................................................
23 Figure 21 Comparison of Axial Offset for Cycle 5 ...................................................
24 Figure 22 Comparison of Axial Offset for Cycle 6 ...................................................
24 Figure 23 Comparison of Axial Offset for Cycle 7 ...................................................
25 Figure 24 Comparison of Axial Offset for Cycle 8 ...................................................
25 Figure 25 Flow Diagram of Calculations 
..................................................................
35 Figure 26 FAH UL(95/95)
Plots for Cycle 14, FAH Near Maximum ...........................
44 Figure 27 FQ UL(95/95)
Plots for Cycle 14, FAH Near Maximum .............................
45 Figure A-1 Measured Signal Divided by Detector Power versus Detector Exposure, O riginal Detectors 
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55 Figure A-2 Measured Signal Divided by Detector Power versus Detector Exposure, Replacement Detectors 
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56 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page v Figure A-3 Calculated Gamma Signal Divided by Detector Power versus Detector Exposure, Original Detectors 
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57 Figure A-4 Calculated Gamma Signal Divided by Detector Power versus Detector Exposure, Replacement Detectors 
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58 Figure A-5 Inferred Neutron Signal Divided by Detector Power versus Detector Exposure, O riginal Detectors 
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59 Figure A-6 Inferred Neutron Signal Divided by Detector Power versus Detector Exposure, Replacement Detectors 
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60 Figure A-7 Neutron Conversion Factor versus Detector Exposure, Original D e te cto rs ........................................................................................... 
..6 1 Figure A-8 Neutron Conversion Factor versus Detector Exposure, Replacement D e te cto rs ........................................................................................... 
..6 2 Figure A-9 Calculated Gamma Divided by Measured Signal versus Detector Exposure, O riginal Detectors 
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63 Figure A-10 Calculated Gamma Divided by Measured Signal versus Detector Exposure, Replacement Detectors 
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64 Figure A-1 1 Depletion Correction Factor ..................................................................
65 Figure A-12 Difference between Predicted and Measured Signals, Original Detectors, Proposed M odel .................................................................
66 Figure A-13 Difference between Predicted and Measured Signals, Replacement Detectors, Proposed M odel .................................................................
67 Figure A-14 Ratio of Measured Signals for Original to Replacement Detectors, B atch 1, C ycle 14 .............................................................................. 
..68 Figure A-15 Ratio of Measured Signals for Original to Replacement Detectors, B atch 1, C ycle 15 .............................................................................. 
..69 Figure A-16 Ratio of Measured Signals for Original to Replacement Detectors, B atch 2 , C ycle 15 .............................................................................. 
..70 Figure B-1 Example Linear Least Square Fits of FAH (UL 95/95) and FQ (UL 95/95) ........ 76 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensina Reoort Paae vi Nomenclature (If applicable)
Acronym FAH Fdh FQ FIDS NCF GCF DPC ST SG SM Cy OTh lOTh avg Rn Cn Cd E RMS 2D 3D Oa Ob Oc Od Ot Or k Definition Enthalpy rise hot channel factor Same as FAH; nomenclature used in YAEC-1855PA Heat flux hot channel factor Fixed Incore Detector System Neutron Conversion Factor Gamma Correction Factor Depletion Correction Factor Total calculated detector signal Calculated detector signal due to gamma Measured signal Unit conversion factor for calculated detector gamma signal Thermal neutron flux Average thermal neutron flux Neutron reaction rate for Pt-1 95 Same as NCF Coefficient of DPC versus detector exposure Detector exposure Root Mean Square Two-dimensional Three-dimensional Standard deviation for signal reproducibility Standard deviation for analytical methods Standard deviation for axial power shape Standard deviation for detector processing Standard deviation for integral detector processing Standard deviation for total system (3D)Standard deviation for integral processing (2D)Confidence interval multiplier AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensinq Report Paqe vii ABSTRACT This document provides modifications to the Fixed Incore Detector System (FIDS)Analysis methodology described in YAEC-1855PA.
The FIDS Analysis methodology has been in use at Seabrook Station to monitor core power distribution surveillance parameters since Cycle 5 in 1995. The FIDS uses fixed platinum detectors which are predominantly gamma sensitive and have a contribution from neutron capture. The FIDS has operated successfully for over 20 years of operation.
In 2007, Seabrook undertook a phased detector replacement project. The Seabrook specification for replacement detectors was written to produce a like-for-like replacement of the original detectors.
However, changes in manufacturing techniques required changes to the FIDS Analysis methodology to incorporate correction factors to normalize the replacement and the original detector signals to the standard detector performance required by the analysis methodology.
Two replacement detector strings were installed in Cycle 14 and three detector strings were installed in Cycle 15. During Cycle 16, Seabrook undertook a program to trend detector performance over the 15 cycles of operation to determine appropriate modifications to the Fixed Incore Detector Code (FINC).Based on the trending analysis, revisions were made to the FIDS Analysis methodology.
The modifications include a more precise method to determine the detector neutron conversion factor to better predict the neutron portion of the fixed detector signal based on the predicted neutron reaction rate. Modifications were also made to track detector exposure and to make a depletion correction to the measured signal based on the detector exposure.
To normalize the replacement and original detectors, correction factors were quantified and incorporated as a multiplier on the measured signal of the replacement detectors.
The FINC code was modified to incorporate the revised FIDS Analysis methodology and the proposed modifications were used to rerun all 15 cycles of flux maps.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensingq Report Page viii The measurement of a core power distribution is built upon a series of comparisons between measured incore signals and predicted incore signals in instrumented locations of the core, and expansion of the resultant power distribution data to uninstrumented locations.
In YAEC-1855PA the uncertainty for detector processing is calculated by comparing detector signals measured at various core conditions to predictions of the detector signals at these same core conditions.
While the FIDS uncertainty based on the difference between measured and predicted detector signals is conservatively bounding, it is not a good representation of the true measurement uncertainty.
The YAEC-1855PA uncertainty analysis is replaced by a method that propagates the uncertainties through the FIDS analysis system using a Monte Carlo statistical simulation and determines a better representation of the true measurement uncertainty for FQ and FAH over a wide range of conditions.
This uncertainty analysis methodology is similar to that employed by the Reference 5 and 6 core power distribution monitoring systems previously reviewed and approved by the NRC.This report describes the detector performance trending analysis of the 15 cycles, documents the proposed modifications to the FIDS Analysis methodology and provides a new determination of the resulting measurement uncertainty for the FQ and FAH Technical Specifications (Tech Specs) surveillance parameters.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Paqie 1 1.0 TECHNICAL EVALULATION

===1.1 Background===
Seabrook Station started Cycle 1 with a combination fixed/movable detector system in 58 locations within the reactor core. The Detector Assemblies at that time accommodated the movable incore detector path, the qualified core exit thermocouple, and the five fixed platinum incore detectors.
The movable detector system was used during the first four cycles of operation and was also used to benchmark the fixed platinum incore detectors.
The fixed detector system was licensed by the NRC during Cycle 3 using the methodology described in YAEC-1855PA (Reference 1). The fixed platinum incore detectors and the methodology described in YAEC-1855PA have been used exclusively to monitor the core since Cycle 5.YAEC-1855PA describes the methodology and uncertainty analysis used to determine the measured core power distribution using the fixed incore detectors and the associated uncertainty.
The fixed incore detectors are self-powered platinum detectors which are predominantly gamma sensitive and produce a signal proportional to the local gamma flux in the reactor core. Although the majority of the signal from the platinum detectors is derived from the gamma flux, a portion of the signal is due to the neutron flux from an n,y reaction.
There are 58 incore detector assemblies distributed radially throughout the core. Each assembly contains 5 individual fixed incore detectors uniformly spaced axially along the height of the core. Thus, a total of 290 detectors are providing continuous core power distribution information.
The detector signals are scanned once per minute and stored such that they may be retrieved and analyzed to determine the three dimensional power distribution and associated Tech Spec surveillance parameters.
The computer software package used to analyze the fixed incore detector signals to determine the power distribution parameters is referred to as S3FINC and is described in YAEC-1855PA.
AREVA Inc. ANP-3243NP Revision 1.Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 2 S3FINC has two major components.
The first is the predictive codes CASMO-3 (Reference
: 2) for cross section generation and gamma response and SIMULATE-3 (Reference
: 3) for predicting the core power distribution and individual detector responses.
The second is the Fixed Incore Detector Code (FINC) which uses the SIMULATE-3 output and measured fixed incore detector signals to determine the measured core power distribution.
Included in YAEC-1855PA is a discussion on how the detector signals are treated as inputs to the methodology.
Important points to note from YAEC-1855PA are:* The use of the CASMO-3/SIMULATE-3 for power distribution prediction
* The use of a standard detector approach for power distribution analysis* The assumption that 25% of the signal is due to neutrons* The overall uncertainty analysis for use with Tech Specs surveillance of FQ and FAH.Although not specifically addressed in YAEC-1855PA, detectors need to be replaced due to long term wear on the high pressure seals and signal connectors.
To this extent, Seabrook has a prototype Replacement Project to replace Detector Assemblies starting with the OR13 (Cycle 14) refueling outage. Two detectors were replaced during OR13 and three were replaced during OR14 (Cycle 15). Seabrook has also embarked on a program to analyze data from the first 15 cycles of operation to quantify trends in the detector performance data and to validate the uncertainty analysis presented in YAEC-1855PA. This topical report serves as a supplement to YAEC-1 855PA. The changes proposed are:* An improved prediction of the neutron component of the detector signal -Neutron Conversion Factor (NCF),* Applying correction factors to the measured detector signal of the replacement detectors to better assure normalization to a standard detector performance 
-Gamma Correction Factor (GCF),
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 3* Accounting and correcting the measured detector signal for detector depletion to better assure normalization to a standard detector performance 
-Depletion Correction (DPC), and* Replacing the uncertainty analysis with a new analysis that better represents the true measurement uncertainty for FQ and FAH over a wide range of conditions by propagating the uncertainties through the FIDS analysis system using a Monte Carlo statistical simulation method.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 4 2.0 NEUTRON CONVERSION FACTOR 2.1 Current Licensing Basis The signal from a platinum fixed incore detector is predominantly from gamma interaction with the platinum.
A portion of the detector signal is from neutron interaction with the platinum, predominantly the Pt-1 95 isotope. It was recognized in both the topical report YAEC-1855PA and in the associated NRC SER dated 12/23/1993 that the fraction of the total detector signal due to neutrons is approximate and not well known at the time. Section 3 of YAEC-1855PA describes the assumptions used to determine an estimate for the fraction of total detector signal due to neutrons.
At that time, public domain studies and a Seabrook specific sensitivity study based on operational data were used to determine the estimate of the fraction neutron component to be used as an input assumption in determining the predicted detector signal. Based on the literature and the sensitivity study, a value of 25% of the total signal was attributed to neutrons.To accommodate the platinum detectors, SIMULATE-3 was modified, to allow the user to input the fractional neutron component of the predicted detector signal. This fraction is given in terms of the total detector signal, and it can be distributed by either or both the fast and thermal neutron flux. The gamma portion of the detector's signal is determined through the total responses determined in CASMO-3 cases and local detector neutron flux calculations within SIMULATE-3.
This is the standard method of detector calculations used within SIMULATE-3.
The total neutron portion of detector signal is determined from the input fraction and is then distributed by the SIMULATE-3 calculated relative local thermal neutron flux levels at the detector locations.
The individual detector's gamma and neutron portions are then summed to determine the detector's total signal.As described in YAEC-1 855PA, a value of 0.25 was used for the thermal neutron component of the predicted detector signal. Thus the total gamma signal was calculated in SIMULATE-3 as:
AREVA Inc. ANP-3243NP Revision I Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 5 The above value of ST was used in FINC starting in Cycle 1.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 6 2.2 Proposed Method To better cover a broader range of reactor core design and operating conditions, a new formulation for determining the neutron component of the predicted detector signal was developed.
Rather than use the straight 25% of the gamma signal to represent the neutron portion, it was determined that a more accurate representation of the total signal could be accomplished by adding a neutron portion to the gamma signal based on total neutron reaction rate. To do this, a new factor called the Neutron Conversion Factor (NCF) was introduced.
The new formulation using the neutron conversion factor is shown in Equation 2.
AREVA Inc. AI Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensina ReDort NP-3243NP Revision 1 Paae 7 I AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 8 3.0 REPLACEMENT DETECTORS 3.1 General The Seabrook specification for replacement detectors was written to produce a like-for-like replacement of the original detectors.
The replacement detectors were built to the original specification and within the as-built attributes of the original detectors including detector geometry, dielectric densities and component material impurities.
The replacement detectors were also constrained to the characteristics assumed in the analysis software licensed for the system. These precautions served to preserve the like-for-like nature of the replacement detectors to the original detector.
Nonetheless, the manufacturing enhancements developed in more than 20 years of detector service result in differences in detector performance as observed in gamma testing of the replacement detectors and archive original detectors.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 9 3.2 Current Licensing Basis As described in YAEC-1855PA, the FINC code depends on the concept of a standard detector.
In the standard detector approach, the raw measured detector signals must be corrected for individual detector differences.
The signal from any individual detector is a function of the incident flux, the amount of detector material and manufacturing differences.
Thus, each detector's signal must be modified to correspond to a signal given by a standard detector.
The standard detector is one built to exact design dimensions.
Since Cycle 1, each measured detector signal is corrected by a sensitivity factor. The sensitivity factor is defined as the ratio of the detector surface area to the surface area of a standard detector.
The data required for the calculation of the sensitivity factors is provided by the detector manufacturer's as-built data of detector length and weight. The sensitivity factors for the replacement detectors were calculated in the same manner as the original detectors in Cycle 1 using the as-built length and weight. This feature in the current licensing basis has not changed. The sensitivity factor is applied to the measured signal and is used to create a standard detector by using the manufacturer's measured weight and length for each detector compared to the weight and length of a standard detector.3.3 Proposed Modification The replacement detector specification required that each individual replacement detector is tested for operation using a gamma source. In addition, to verify compatibility, original archive detectors are tested in the same gamma source environment.
During the testing, it was noted that the replacement detectors produced a lower signal than the original detectors in the same gamma field and could not be corrected by application of the simple sensitivity factor based only on as-built detector length and weight.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 10 The Gamma Correction Factor (GCF) was introduced in Cycle 14 to make the replacement detector signal compatible with the signal from the original detectors.
The GCF is input to FINC as a simple multiplier on the measured signal for the replacement detectors.
Different values of the GCF are used for the Batch 1 and Batch 2 replacement detectors based on changes in the manufacturing process. As part of the trending analysis, the GCF was refined through the trending analysis of Appendix A as shown in Figure A-14, Figure A-15, and Figure A-16. The trending analysis compared the difference in signal between the replacement detectors and their symmetric partners over Cycles 14 and 15 for the Batch 1 replacement detectors and over Cycle 15 for the Batch 2 replacement detectors.
The GCF values reflect in-reactor measurements of symmetric partners in the Seabrook reactor environment.
The value of Batch 1 GCF is 1.0577 and the Batch 2 GCF is 1.0849. The Batch 2 replacement detectors defined the future manufacturing process. It is the intent to use the Batch 2 GCF for future batches of replacement detectors.
However, since the magnitude of the detector signal can be affected by the manufacturing process, future batches of detectors may require their own GCF determined through testing.
AREVA Inc. AM'Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensino Renort JP-3243NP Revision 1 Paae 11 Licensina Renort 4.0 4.1 DEPLETION CORRECTION FACTOR Current Licensing Basis The current licensing basis does not include a depletion correction factor. The modeling of the effects of elemental platinum depletion is not required as described in YAEC-1855PA in response to RAI Question 4. [] Thus, no provisions were provided in the current licensing basis for a depletion correction.

===4.2 Proposed===
Modification
] This effect is primarily due to the consumption of the Pt-195 isotope which is the predominant contributor to the neutron component of the total gamma signal of the detector.From the trending analysis covering all 15 cycles, a linear Depletion Correction (DPC)was derived in Appendix A as a function of detector exposure as shown in Figure A-1 1.Detector exposure is the accumulated fuel exposure of the assembly containing the detector, averaged over the detector length. With the proposed modification of FINC, the DPC will be calculated for each detector based on detector exposures using the derived curve. The DPC will be applied to each individual detector and will vary with detector exposure.
[From Equation 3, the depletion correction factor utilizes the detector exposure to obtain a multiplier to be applied to the measured signal for each detector.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1 855PA Licensing Report Page 12 5.0 COMPARISON OF FINC RESULTS 5.1 General With the completion of the trending analysis in Appendix A, the proposed modifications to FINC were established.
To determine the effect of these modifications on the surveillance parameters, all 15 cycles of flux maps were rerun with the revised version of FINC incorporating the proposed modifications.
The 15 cycles provides a good test of the proposed modifications to FINC under an array of operating conditions that involved changes in fuel management strategy, changes in fuel design, power uprate, normal core tilt condition and axial offset anomalies.
The evaluation of the data is for flux maps that were run under equilibrium conditions as would be the case for normal surveillance.

===5.2 Surveillance===

Parameter Comparisons This section shows the comparison of the original FINC version to the modified FINC version for the Tech Spec surveillance parameters.
Although all 15 cycles of flux maps were rerun with the modified version of FINC, comparisons are provided here for the first eight cycles. During these cycles the licensing model used a fixed 25% of the gamma signal as the neutron portion of the signal and did not include a correction for detector exposure.
The proposed modifications to FINC utilize a neutron conversion factor and the neutron reaction rate to determine the neutron portion of the signal. The proposed model also includes a correction for depletion based on the exposure of each individual detector.
The comparisons for the heat flux hot channel factor FQ are provided in Figure 1 through Figure 8. The value of FQ includes the current measurement uncertainty of 5.21% and the engineering heat flux uncertainty of 3%.The comparisons for the enthalpy rise hot channel factor FAH are provided in Figure 9 through Figure 16 and the comparisons for axial offset are provided in Figure 17 through Figure 24. FAH values are shown without any uncertainty because the uncertainty factor is applied to the limit, as specified in the core operating limits report.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 13 The results provided in Figure 1 through Figure 24 show that performance of the proposed model compares well to the current licensing basis model. In these figures the proposed model contains the neutron conversion factor, detector exposure tracking and the depletion correction.
The NCF was introduced in Cycle 9 in 2002 so that a comparison to the original FINC version, consistent with the current licensing basis methodology could not be made after Cycle 8.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1 855PA Licensinq Report Paqie 14 Figure 1 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 1 2.20 -2.00 1 1.80 -0E1.60. -1.40 -1.20 -*Licensing Model OProposed Model 1.00 -0 2000 4000 6000 8000 10000 12000 14D00 Cyde Exposure (MWD/MTU)Figure 2 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 2 1.95 1.90 -1.85 E E: 1.80 [] 0 1.75 -00 1.75 -0 1.70* Licensing Model O Proposed Model 1.65 0 2000 4000 6000 8000 10000 12000 Cyde Exposure (MWD/MTU)
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensina ReDort Paae 15 Figure 3 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 3 2.00 1.95 00 1.90 E 0 E1.85 1.80 -+1.75 -0* Licensing Model OProposed Model 1.70 1 1..0 2000 4000 6000 8000 10000 12000 14000 16000 Cyde Exposure (MWD/MTU)Figure 4 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 4 1.90 1.85 1.80 E 1.75 1.70 1.65 1.60 1.55 V POD 100 0*Licensing Model OProposed Model 0 5000 10000 Cyde Exposure (MWD/MTU)15000 20000 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1 855PA Licensing Report Page 16 Figure 5 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 5 2.00 , 1.95 ___---__0___-__
_1.90 [ 113 t 0 1.85 I=0 X 180 -1.75o 1.70 -* Licensing Model 0Proposed Model 1.65 1 T 0 5000 10000 15000 200D0 Cyde Exposure (MWD/MIU)Figure 6 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 6 2.05.2.00 1.95 S1.90.X 1.85 1.80*Licensing Model OProposed Model 1.70 1 1 1 0 5000 10000 15000 20000 25000 Cyde Exposure (MWD/MTU)
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensinq Report Page 17 Figure 7 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 7 1.90 1.85 E 1.70 1.65 1 Licensing Model -0 Proposed Model 1.60 ,,, 0 5000 10000 15000 20D00 Cycle Exposure (MWD/MTU)Figure 8 Comparison of Heat Flux Hot Channel Factor FQ for Cycle 8 1.90 1.88 1.86 1.84 E E 1.801.78 1.76 1.74 1.72 1.70 20000 0 5000 100O0 15000 Cycle Exposure (MWD/MTU)
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensinq Report Page 18 Figure 9 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle I 1.40 1.38 1.36 1.34 13 E 1.32 91.30 1.28 1.26 1.24 p 0*0 0* Licensing Model 0'Proposed Model 0 2000 4000 6000 8000 10000 Cyde Exposure (MWD/MTU)12000 14000 Figure 10 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 2 1.46[0 D 1.44 1.42 -= 1.40 1.38 1.36#Licensing Model r-Proposed Model 1.34 -I 0 5000 10000 150D0 20000 Cyde Exposure (MWD/MTU)
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 19 Figure 11 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 3 1.46+0 0 00 1.45 0 0 0*E_E1.43 1.42 -1.41*Licensing Model OProposed Model 1.40 .......0 2000 4000 6000 8000 10000 12000 14000 16000 Cyde Exposure (MWD/MTU)Figure 12 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 4 1.46 n n 1.44 i*1.42 1.40 1.38 1.36*Licensing Model OProposed Model I 1.34 -I 0 5000 10000 15000 20000 Cyde Exposure (MWD/MTU)
AREVA Inc. A Seabrook Station Unit 1 Fixed I ncore Detector.System Analysis Supplement to YAEC-1855PA Licensino Renort 4P-3243NP Revision 1 Paae 20 Figure 13 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 5 1.49 1.48 1.47 1.46 U' 1.45_E 1.44 1.43 o n r 0p*Licensing Model n Proposed Model 1.42 1.41 1.40 0 5000 10000 Cycle Exposure (MWD/MTU)15000 20000 Figure 14 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 6 1.56 1.54 1.52 A 17 1E 5 x 1.48 1.46- i_1.44 , 1.42 Licensing Model OProposed Model 0 5000 10000 15000 20000 25000 Clyde Exposure (MWD/MTU)
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 21 Figure 15 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 7 1.45 1.44 1.43 1.42 E 1.41 E O S1.40 1.39 1.38 1.37 1.36 0 5000 10000 15000 2000O Cyde Exposure (MWD/MTU)Figure 16 Comparison of Enthalpy Rise Hot Channel Factor FAH for Cycle 8 1.44 144 1.43 1.431 E1.42~ 00 1.40 -1.39 -1.9 #Licensing Mode 1 0Proposed ModelI 0 5000 10000 15000 20000 Cycle Exposure (MWD/MTU)
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 22 Figure 17 Comparison of Axial Offset for Cycle 1 0.0-1.0-2.0--3.0 Z -4.0 950-6.0-7.0-8.0-9.0 O [.* 00*0 0 0*Licensing Model OProposed Model 2000i 100 120 40 0 200D 4000 6000 8000 CYde Exposure (MWD/MTU)10000 120D0 14000 6.0 5.0 4.0 3.0 2.0 1.0 0.0-1.0-2.0-3.0-4.0 Figure 18 Comparison of Axial Offset for Cycle 2 0.,0 [0 *0 P
* de*Licensing Model OProposed Model 0 2000 4000 6000 8000 Cycle Exposure (MWD/MT1)10000 12000 AREVA Inc. AI, Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA L icensina Renort JP-3243NP Revision 1 Paae 23 Figure 19 Comparison of Axial Offset for Cycle 3 0.0--0.5-1.0- 13..0_9-2.0- A-+q S0 *-3.0 B-0-3.5-Licensing Model 0 Proposed Model-4.0-0 2000 4000 6000 8000 10000 12000 14000 16000 Cyde Exposure (MWD/MTU)1-46 1.44 1.42 E_E 1.40 1.38 Figure 20 Comparison of Axial Offset for Cycle 4 0* *0 0 0 +#* Licensing Model OProposed Model I 1*1.36 1.34 0 5000 10000 Cyde Exposure (MWD/MTU)15000 20000 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit I Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensinq Report Page 24 Figure 21 Comparison of Axial Offset for Cycle 5 3 2.0 1.0 0.0-1.0-2.0-3.0-4.0-5.0-6.0*Licensing Model 0 Proposed Model "0--~J-5 0w 0~ ,d 0[ED .*+ ,, n o O 0 5000 10000 Cyde Exposure (MWD/MTU)15000 20000 4.0 3.0 2.0 1.0 0.0-1.0-2.0.2.1 Figure 22 Comparison of Axial Offset for Cycle 6 4,,5 A.- FI I I ~cen~ng odi ropoedM~iA
-3.0-4.0-5.0-6.0 0 5000 10000 15000 20000 25000 Cyde Exposure (MWD/MTU)
AREVA Inc. AI'Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensina Report 4P-3243NP Revision 1 Paoe 25 Figure 23 Comparison of Axial Offset for Cycle 7 4.0 -3.0-2.0-1.0 *Licensing Model 0 Proposed Model +0-3.0-4.0-5.0 0 5000 10000 15000 20000 Cyde Exposure (MWO/MTU)Figure 24 Comparison of Axial Offset for Cycle 8 0.0-0.5-1.0 1. 5.5 I -2.0-2.5-3.0-3.5-4.0 0 5000 10000 15000 Cyde Exposure (MWD/MnU)20000 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1 855PA Licensinq Report Paqe 26 5.3 Statistical Results With the proposed modifications, a new uncertainty analysis was performed that better represents the true measurement uncertainty for FQ and FAH over a wide range of conditions by propagating the uncertainties through the FIDS analysis system using a Monte Carlo statistical simulation method. This statistical simulation method replaces the signal reproducibility and detector processing uncertainty terms in the YAEC-1855PA uncertainty analysis.
[] The results of the simulation analysis were statistically combined with the Analytical Methods and Axial Signal Power Shape uncertainty terms from YAEC-1855PA, which remained unchanged, and determined a total measurement uncertainty of the FIDS analysis system of less than 4.0% for FAH and less than 5% for FQ.The accuracy and functionality of the FIDS analysis system remains comparable to the original YAEC-1855PA analysis and the Moveable Incore Detector System.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 27 6.0 UNCERTAINTY ANALYSIS 6.1 Current Licensing Basis As noted in YAEC-1 855PA, the uncertainty of the fixed incore detector system is addressed in four individual parts. Each of these parts are quantified and then statistically combined to achieve a total system uncertainty at a 95/95 confidence level with a one-sided tolerance limit. The uncertainties associated with FAH and FQ have traditionally been treated independently.
The uncertainty in the three-dimensional parameter FQ contains all axial and radial components of the system uncertainty.
However, the two-dimensional parameter FAH is an axially integrated quantity that does not contain the axial uncertainty component.
Uncertainties for each of these quantities are defined independently below.The total system uncertainty applied to the three-dimensional quantity of FQ defined as:
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 28 The second uncertainty factor is applied to the two-dimensional axially integrated quantity of FAH. The radial or FAH uncertainty requires the combination of three of the four uncertainty components.
The axial power shape uncertainty does not apply to the integrated radial parameters and the radial detector processing uncertainty contains only the axially integrated processing component.
The system two-dimensional uncertainty, as applied to FAH, is defined as: The 95/95 confidence level with a one-sided tolerance limit can be calculated from the standard deviation for each component and the appropriate confidence level multiplier.
The confidence level multiplier (k) is directly dependent on the size of the data set and was determined from Reference
: 4. For reference, the components and confidence factors from YAEC-1 855PA are provided in Table 1 below.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1 855PA Licensing Report Paae 29 Table I Uncertainty Components and Confidence Multipliers from YAEC-1855PA AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 30 6.2 Proposed Uncertainty Modifications

====6.2.1 Overview====
A new uncertainty analysis was performed that better represents the true measurement uncertainty for FQ and FAH over a wide range of conditions by propagating the uncertainties through the FIDS analysis system using a Monte Carlo statistical simulation method. This statistical simulation method replaces the signal reproducibility (aa), and detector processing (Gd and Ge) uncertainty terms in the YAEC-1855PA uncertainty analysis.The FIDS analysis system is statistical in nature. Consequently, the determination of the measured peaking factor is affected by detector measurement variability, the number and layout of available detectors, signal replacement techniques, expansion of the measured power to uninstrumented core locations, and any differences between predicted and true power distribution.
Accordingly, a range of conditions need to be considered in determination of the system uncertainty.
For this reason the FIDS analysis system uncertainty has been determined using the Monte Carlo statistical simulation method in which [] The FIDS analysis system determines the measured power distribution FAH and FQ surveillance parameters from these simulated detector signals using the power distribution processing methodology described in Section 4.0 of YAEC-1855PA, including the proposed modifications described in Sections 2.2, 3.3, and 4.2 of this document.
In the simulation, a range of detector failures is considered in combination with a range of perturbations between the predicted and true power distribution.
This uncertainty analysis methodology is similar to that employed by the Reference 5 and 6 core power distribution monitoring systems previously reviewed and approved by the NRC.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 31 6.2.2 Methodology The FIDS analysis system contains two major software components:
FINC and SIMULATE-3.
In normal core monitoring, SIMULATE-3 provides the predicted detector signals and a predicted power distribution.
FINC uses the measured and predicted detector signals to adjust the predicted power distribution to produce the measured power distribution.
This algorithm is described in YAEC-1855PA, Section 4.4.For the uncertainty calculation, [I AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensinq Report Page 32 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 33] The uncertainty factors for Analytical Methods and Axial Signal Power Shape (ob and Oc in Equations 7 and 8 of YAEC-1855PA) are retained because those effects cannot be analyzed by this uncertainty methodology.
FQ UL(95/95) and FAH UL(95/95) are also computed with an equivalent non-parametric method that does not assume the distributions are normal. [[I AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1 855PA Licensing Report Page 34 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensingq Report Page 35 Figure 25 Flow Diagram of Calculations AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 36 6.2.3 Uncertainty Calculation Details 6.2.3.1 Physics Analytical Methods Uncertainty The CASMO-3 and SIMULATE-3 code package used to generate all analytical predictions for power distribution related parameters has not changed since the initial licensing analysis in YAEC-1855PA.
Since the physics analysis methods have not changed, the analytical methods uncertainty, 0 b, has not changed 6.2.3.2 Axial Power Shape Uncertainty As noted in YAEC-1855PA, the axial profiles calculated by SIMULATE-3 are the basis for determining the measured axial power shapes from the fixed detector data within the core. Measured axial power distributions are determined from the fixed incore detector signals and from the detailed axial power shapes generated by the SIMULATE-3 analytical model. Since the SIMULATE-3 methodology has not changed, the axial power shape uncertainty, ao, has not changed.6.2.3.3 Simulation Uncertainty Analysis 6.2.3.3.1 Operating State Points Three operating state points were chosen for the uncertainty analysis:* Cycle 14, cycle exposure where FNH is near the maximum, excluding the beginning of cycle non-equilibrium cases.* Cycle 14, cycle exposure where FQ is near the maximum, excluding the beginning of cycle non-equilibrium cases.* Cycle 13, cycle exposure where axial offset is near minimum (largest negative value)and the Axial Offset mismatch is also near maximum.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1 855PA Licensing Report Page 37 6.2.3.3.2 Perturbations in Measured Power Distributions 6.2.3.3.3 Detector Signal Variance Detector signal variance consists of reproducibility of detector responses, uncertainty in plant parameter measurements, variability in reactor conditions, uncertainty in detector sensitivity corrections (including sensitivity, gamma, and depletion corrections), and uncertainty in the detector predictive model. [I AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 38 6.2.4 Uncertainty Calculation Results Three reactor operating state points were analyzed.
[I AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1 855PA Licensinq Report Pa-qe 39 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 40 AREVA Inc. AIP Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA R~nnrt XlP-3243NP Revision 1 Paae 41 Licensinn Report Paoe 41 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 42 6.2.5 Analysis of Significant Trends AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Paqe 43 Table 2 95/95 Uncertainty Limits for FAH and FQ AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 44 Figure 26 FAH UL(95/95)
Plots for Cycle 14, FAH Near Maximum AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 45 Figure 27 FQ UL(95/95)
Plots for Cycle 14, FAH Near Maximum AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 46 

==7.0 CONCLUSION==
S The information provided here to supplement YAEC-1 855PA shows the modifications made to the FINC code to improve the accuracy and accommodate replacement detectors consistent with the concept of the standard detector as noted in YAEC-1855PA. The modifications to FINC utilize the information determined from an extensive trending program to analyze the first 15 cycles of operation of Seabrook.
The rerun of 15 cycles of flux maps showed detector performance data Which provides confidence in the proposed method of analysis.The current licensing basis uncertainty analysis methodology is replaced with a new methodology that determines the true measurement uncertainty for FQ and FAH. These uncertainties are specific to the analytical physics methods, CASMO-3 and SIMULATE-3 and the incore data processing code, FINC, and the general design of the platinum fixed detectors for Seabrook Station. Conservatively bounding measurement uncertainty values of 4.0% for FAH and 5.0% for FQ for the FIDS analysis methodology are proposed.
These are slightly higher than the values supported by the uncertainty analysis and are consistent with the Moveable Incore Detector System (MIDS).
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1 855PA Licensinq Report Paqe 47 

==8.0 REFERENCES==
: 1. Joseph P. Gorski, "Seabrook Station Unit 1 Fixed Incore Detector System Analysis," YAEC-1855PA, October 1992.2. M. Edenius and Bengt-Herman Forssen, "CASMO-3:
A Fuel Assembly Burnup Program, User's Manual," STUDSVIK/NFA-89/3, January 1991.3. K.S. Smith, K.R. Rempe and D.M. VerPlanck, "SIMULATE-3:
Advanced Three-Dimensional Two-Group Reactor Analysis Code, Methodology," STUDSVIK/NFA-89-04, November 1989.4. D.B. Owen, Factors for One-Sided Tolerance Limits and for Variables Sampling Plans, SCR607, US Dept. of Commerce, March 1963.5. R. Kochendarfer, "Statistical Universal Power Reconstruction with Fixed Margin Technical Specifications," ANP-1 0301 P-A. AREVA, Inc., September 2013.6. R. Kochendarfer, C. T. Rombaugh and A.Y. Cheng, Fixed Margin Technical Specifications," BAW-10158P-A.
Babcock and Wilcox, August 1986.7. Carl A. Bennett and Normal L. Franklin, "Statistical Analysis in Chemistry and the Chemical Industry", John Wiley & Sons, New York, 1954.8. Gerald J. Hahn and Samuel Shapiro, "Statistical Models in Engineering", John Wiley & Sons Inc., New York, 1967.9. Mary Gibbons Natrella, "Experimental Statistics", National Bureau of Standards", 1963.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 48 APPENDIX A The trending analysis processed the measured signal data for 15 cycles of Seabrook operation.
The trending analysis used the calculation sequence of cross section generation by CASMO-3, power prediction generation by SIMULATE-3 and measured data processed by FINC. The CASMO-3 and SIMULATE-3 codes are the same versions used in YAEC-1855PA and have not changed. The trending analysis contained the use of the Neutron Conversion Factor (NCF) that was introduced in Cycle 9.CASMO-3 provides the cross section input and gamma response to SIMULATE-3.
The power distribution predictions, predicted gamma signal, and neutron reaction rate are produced by SIMULATE-3.
For the trending analysis, the data extracted from SIMULATE-3 was the three dimensional power distributions, the detector gamma signal and the nodal neutron reaction rate for platinum.
FINC processed the measured signals correcting for the surface area to obtain results for a standard detector.Post processing software and Excel spreadsheets were used to analyze the data. The following pieces of data were used in the trending analysis: " The measured signal, SM, from FINC corrected for surface area to correct to a standard detector.* The predicted gamma signal, SG, for the five detector levels came from SIMULATE-3 without modification." The detector neutron reaction rate came from the 3D predicted nodal neutron reaction rate for platinum from SIMULATE-3 and collapsed by the post processing software over the detector length and axial location to obtain Rn.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensinq Report Page 49" Detector power was generated by the post processing software from the 3D nodal assembly power fraction from SIMULATE-3.
The nodal assembly power fraction was collapsed over the detector length and axial location to generate a detector power in megawatts.
* Detector exposure was generated by the post processing software from the 3D nodal assembly exposure from SIMULATE-3.
The nodal assembly exposure was collapsed over the detector length and axial location to generate a detector exposure in GWD/MTU. The detector exposure was accumulated to be current for each flux map.* A power independent measured detector signal was generated by the post processing software by dividing the measured signal, SM, by the detector power.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 50 The trending analysis is based on 15 cycles of Seabrook operation as summarized below:* Seabrook contains 58 detector strings with 5 detectors per string.* The 15 cycles comprise 813 reactor flux maps." Failed detectors or detector strings were removed, i.e., no signal produced." The analysis considered only original detectors for the determination of the NCF and DPC. Replacement detectors were incorporated into the figures to show consistency.
* This resulted in 221,226 unique data points." A total of 145 anomalous flux maps were removed. Non-equilibrium flux maps and flux maps with an axial offset anomaly were removed in order to obtain a good estimate of the NCF and DPC parameters.
A total of 145 flux maps were removed.* The result was that 180,393 unique data points were used in the trending analysis.The results of the trending analysis are provided in Figure A-1 through Figure A-16.The trending analysis for the original detectors is over all 15 cycles while the trending for the replacement detectors is over Cycle 14 and 15 for the Batch 1 replacement detectors and Cycle 15 for the Batch 2. replacement detectors.
Where applicable, the figures show a linear fit through the data as a solid black line.Figure A-1 shows the measured signal (SM) divided by the detector power versus detector exposure for the original detectors.
Figure A-2 shows the measured signal divided by the detector power versus detector exposure for the replacement detectors.
The overall trend shows a decrease in signal as a function of detector exposure for both the original and replacement detectors.
The trend shows changes due to changes in neutron and gamma spectrum during cycle burnup; changes from cycle to cycle due to core design and operating conditions; and changes due detector depletion.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1 855PA Licensing Report Page 51 Figure A-3 shows the calculated gamma signal (Cy*SG from Equation 2 in Section 2.2)divided by the detector power versus detector exposure for the original detectors.
Figure A-4 shows the calculated gamma signal divided by the detector power versus detector exposure for the for the replacement detectors.
The overall trend shows a decrease in the calculated gamma signal as a function of detector exposure for both the original and replacement detectors.
The trend shows that the predictive model captures the effect of changes during the cycle, changes in core design and fuel management strategy and changes in operation conditions.
The predictive model does not account for detector depletion.
Figure A-5 shows the inferred neutron signal [] divided by the detector power versus detector exposure for the original detectors.
The overall trend shows a decrease in the inferred neutron signal as a function of detector exposure.
Figure A-6 shows the inferred neutron signal divided by the detector power versus detector exposure for the replacement detectors.
Due to the short exposure time and the small number of replacement detectors, the overall trend shows no discernible decrease in the inferred neutron signal as a function of detector exposure.To isolate the effect of detector depletion, the Neutron Conversion Factor (NCF)calculated from Equation 6 is used. Figure A-7 shows the NCF versus detector exposure for the original detectors.
The overall trend shows very slight decrease in the NCF as a function of detector exposure.
From this data a linear relationship for the NCF was determined as NCF = A + B*E where E is the detector exposure in GWD/MTU and A and B are the constants of the linear equation.
For comparison, Figure A-8 shows the NCF versus detector exposure for the for the replacement detectors.
Again, due to the short exposure and the small number of replacement detectors, the overall trend shows no discernible decrease or increase in the NCF as a function of detector exposure.
It should be noted that the NCF for all detectors is derived from the original detectors only. Figure A-8 is intended to show the similarity in NCF between original and replacement detectors.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensinq Report Paqe 52 Figure A-9 shows the calculated gamma signal divided by the measured signal as a function of detector exposure for the original detectors.
From this figure it is clear that the gamma portion of the signal has been approximately 75% of the total signal. The refinement made in Cycle 9 to use the NCF rather than a straight 25% of the gamma portion of the signal more accurately represents the change in the neutron portion of the signal with changing core conditions.
Figure A-10 shows the calculated gamma signal divided by the measured signal as a function of detector exposure for the replacement detectors.
The trend of the replacement detectors appears to be consistent with that of the original detectors.
From the 15 cycles of trend data, there are observed trends in the measured signal, the calculated gamma signal, and the inferred neutron signal. [I AREVA Inc. AI Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1 855PA Licensina Renort NP-3243NP Revision 1 Paqe 53 Figure A-12 shows the difference between the predicted and measured signals for the original detectors using the proposed model. This figure shows there is no trend in the data with exposure and provides a basis for the proposed model.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 54 Replacement detector strings were installed in Cycle 14 (Batch 1) and Cycle 15 (Batch 2). The replacement detectors were constructed to be similar to the original detectors, but are slightly less sensitive than the original detectors due primarily to changes in the manufacturing process. The change in sensitivity was noted and the FINC code was modified to introduce a batch dependent Gamma Correction Factor. As part of the trending analysis, the change in the Batch 1 and Batch 2 sensitivity was refined by comparing the measured signal from the replacement detectors to their symmetric partners of original detectors.
The detector signals were corrected for depletion effects using the DPC from above. The comparisons are shown graphically in Figure A-14 and Figure A-15 for the Batch 1 detectors and in Figure A-16 for the Batch 2 detectors.
Figure A-1 3 shows the difference between the predicted and measured signals for the replacement detectors using the proposed model with the Gamma Correction Factor.This figure shows there is no trend in the data with exposure but a small bias. Since the bias is small, this provides a basis for the proposed model with the replacement detectors.
Using the approach of comparing to symmetric partners, the Gamma Correction Factor (GCF) is computed as: Equation 11 GCF = Signal from Original Detector
* DPC Signal from Replacement Detector
* DPC Gamma Correction Factor for the replacement detectors is provided by detector batch and the GCF for Batch 1 is 1.0577 and the GCF for Batch 2 is 1.0849. These values with be input to FINC as constants to be applied to the Batch 1 and Batch 2 measured signals as simple multipliers.
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 55 Figure A-1 Measured Signal Divided by Detector Power versus Detector Exposure, Original Detectors AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 56 Figure A-2 Measured Signal Divided by Detector Power versus Detector Exposure, Replacement Detectors 
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AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 57 Figure A-3 Calculated Gamma Signal Divided by Detector Power versus Detector Exposure, Original Detectors AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 58-Figure A-4 Calculated Gamma Signal Divided by Detector Power versus Detector Exposure, Replacement Detectqor AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 59 Figure A-5 Inferred Neutron Signal Divided by Detector Power versus Detector Exposure, Original Detectors AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensinq Report Page 60-Figure A-6 Inferred Neutron Signal Divided by Detector Power versus Detector Exposure, Replacement Detectors AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 61 Figure A-7 Neutron Conversion Factor versus Detector Exposure, Original Detectors AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 62 Figure A-8 Neutron Conversion Factor versus Detector Exposure, Replacement Detectors AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 63 Figure A-9 Calculated Gamma Divided by Measured Signal versus Detector Exposure, Original Detectors AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 64 Figure A-10 Calculated Gamma Divided by Measured Signal versus Detector Exposure, Replacement Detectors AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 65 Figure A-11 Depletion Correction Factor AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 66 Figure A-12 Difference between Predicted and Measured Signals, Original Detectors, Proposed Model AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 67 Figure A-1 3 Difference between Predicted and Measured Signals, Replacement Detectors, Proposed Model AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 68 Figure A-14 Ratio of Measured Signals for Original to Replacement Detectors, Batch 1, Cycle 14 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 69 Figure A-15 Ratio of Measured Signals for Original to Replacement Detectors, Batch 1, Cycle 15 -
AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 70-Figure A-16 Ratio of Measured Signals for Original to Replacement Detectors, Batch 2, Cycle 15 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensinq Report Page 71 APPENDIX B AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Page 72 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensing Report Paqe 73 AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensingq Report Page 74 AREVA Inc. A Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1 855PA Licensing Report 4P-3243NP Revision 1 Paqe 75 Table B-1 Conservative Trend Slope of FAH UL(95/95) and FQ UL(95/95) for a Maximum of 8 Failed Detector Strings AREVA Inc. ANP-3243NP Revision 1 Seabrook Station Unit 1 Fixed Incore Detector System Analysis Supplement to YAEC-1855PA Licensinq Report Paqe 76 Figure B-1 Example Linear Least Square Fits of FAH (UL 95/95) and FQ (UL 95/95)}}