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{{#Wiki_filter:XI.M15 Neutron Noise Monitoring 1 AUDIT W ORKSHEET  GALL R EPORT AMP PLANT: ______________________________
{{#Wiki_filter:AUDIT WORKSHEET GALL REPORT AMP PLANT: ______________________________
LRA AMP: __________________________
LRA AMP: __________________________                                                         REVIEWER: ______________________
R EVIEWER: ______________________
GALL AMP: XI.M15, Neutron Noise Monitoring                                                 DATE: __________________________
GALL AMP: XI.M15, Neutron Noise Monitoring DATE: __________________________
Program             Auditable GALL Criteria                                               Documentation of Audit Finding Element Program             A. The program relies on monitoring the excore neutron detector       Consistent with GALL AMP:      Yes  No Description          signals due to core motion to detect and monitor significant loss     Document(s) used to confirm Criteria:
Program Element Auditable GALL Criteria Documentation of Audit Finding Program Description A. The program relies on monitoring the excore neutron detector signals due to core motion to detect and monitor significant loss of axial preload at the core support barrel's upper support flange in pressurized water reactors (PWRs). This inservice monitoring program is based on the recommendations from the American Society of Mechanical Engineers operation and maintenance standards and guides (ASME OM-S/G)-1997, Part 5, "Inservice Monitoring of Core Support Barrel Axial Preload in Pressurized Water Reactors Power Plants." Consistent with GALL AMP:
of axial preload at the core support barrels upper support flange in pressurized water reactors (PWRs). This inservice monitoring program is based on the recommendations from the American Society of Mechanical Engineers operation and maintenance             Comment:
Yes No Document(s) used to confirm Criteria:  
standards and guides (ASME OM-S/G)-1997, Part 5, Inservice Monitoring of Core Support Barrel Axial Preload in Pressurized Water Reactors Power Plants.
: 1. Scope of          A. The program includes measures to monitor and detect loss of        Consistent with GALL AMP:      Yes  No Program              axial preload (loss of axial restraint) at the core support barrels  Document(s) used to confirm Criteria:
upper support flange in PWRs. The loss of axial restraint may arise from long-term changes resulting from abnormal wear at the reactor vessel core barrel mating surface or short-term changes due to improper installation of the reactor internals.        Comment The program also includes guidelines for further data acquisition that may be needed to define future plant operation and/or program plans in order to maintain the capability of the structure/components to perform the intended function.
: 2. Preventive        A. The program is a monitoring/detection program that provides        Consistent with GALL AMP:      Yes   No Actions              early indication and detection of the onset of aging degradation      Document(s) used to confirm Criteria:
of the core support barrelhold-down mechanism prior to a scheduled shutdown, thus reducing outage time and avoiding potential damage to the core support barrel and fuel assemblies. The AMP does not rely on preventive actions.              Comment:
XI.M15 Neutron Noise Monitoring                                                          1


Comment: 1. Scope of Program A. The program includes measures to monitor and detect loss of axial preload (loss of axial restraint) at the core support barrel's upper support flange in PWRs. The loss of axial restraint may arise from long-term changes resulting from abnormal wear at the reactor vessel core barrel mating surface or short-term changes due to improper installation of the reactor internals. The program also includes guidelines for further data acquisition that may be needed to define future plant operation and/or program plans in order to maintain the capability of the structure/components to perform the intended function. Consistent with GALL AMP:
Program              Auditable GALL Criteria                                              Documentation of Audit Finding Element
Yes No Document(s) used to confirm Criteria:
: 3. Parameters        A. The program relies on the use of excore neutron detector          Consistent with GALL AMP:      Yes  No Monitored/          signals to provide information on the conditions of the axial         Document(s) used to confirm Criteria:
Comment 2. Preventive Actions A. The program is a monitoring/detection program that provides early indication and detection of the onset of aging degradation of the core support barrelhold-down mechanism prior to a scheduled shutdown, thus reducing outage time and avoiding potential damage to the core support barrel and fuel assemblies. The AMP does not rely on preventive actions. Consistent with GALL AMP:
Inspected            preload. The excore neutron flux signal is composed of a steady state, direct current (DC) component that arises from the neutron flux produced by the power operation of the reactor, as well as a fluctuating (noise-like) component. This fluctuating        Comment:
Yes  No Document(s) used to confirm Criteria:
signal arises from the core reactivity changes due to lateral core motion from the loss of axial preload. This core motion is mainly the result of beam mode vibration of the core support barrel.
Despite the fact that this beam mode vibration provides only a very weak neutron noise source, it may be reliably detected and identified through Fourier Analysis of the fluctuating signal component of the excore neutron flux signal. This signal component has the characteristics of having 180-degree shifts and a high degree of coherence between signals obtained from pairs of excore neutron detectors that are positioned on diametrically opposite sides of the core. The neutron noise signals are characterized by parameters, which include the auto correlation, cross correlation, coherence, and phase. These parameters are to be monitored and evaluated.
: 4. Detection of      A. Flow-induced vibration of the core support barrel will change      Consistent with GALL AMP:       Yes   No Aging Effects        the thickness of the downcomer annulus (water gap). This              Document(s) used to confirm Criteria:
variation in the thickness will give rise to fluctuating changes in the neutron flux, as monitored by the excore neutron detectors.
The natural frequencies and the amplitudes of the vibratory motion of the core barrel are related to the effective axial          Comment:
preload at the upper support flange of the core support barrel.
Monitoring of the neutron noise signal obtained with the neutron flux detectors located around the external periphery of the reactor vessel provides detection of anomalous vibrational motion of the core support barrel, and hence significant loss of the axial preload. Decrease in the axial preload leads to decreases in the core support barrel beam mode frequency and an increase in the magnitude of the noise signal. The overall XI.M15 Neutron Noise Monitoring                                                          2


Comment:
Program             Auditable GALL Criteria                                             Documentation of Audit Finding Element effect of a decrease in the axial preload is to shift the neutron noise power spectrum toward larger amplitudes for the lower frequency region.
XI.M15 Neutron Noise Monitoring 2 Program Element Auditable GALL Criteria Documentation of Audit Finding 3. Parameters Monitored/ Inspected A. The program relies on the use of excore neutron detector signals to provide information on the conditions of the axial preload. The excore neutron flux signal is composed of a steady state, direct current (DC) component that arises from the neutron flux produced by the power operation of the reactor, as well as a fluctuating (noise-like) component. This fluctuating signal arises from the core reactivity changes due to lateral core motion from the loss of axial preload. This core motion is mainly the result of beam mode vibration of the core support barrel. Despite the fact that this beam mode vibration provides only a very weak neutron noise source, it may be reliably detected and identified through Fourier Analysis of the fluctuating signal component of the excore neutron flux signal. This signal component has the characteristics of having 180-degree shifts and a high degree of coherence between signals obtained from pairs of excore neutron detectors that are positioned on diametrically opposite sides of the core. The neutron noise signals are characterized by parameters, which include the auto correlation, cross correlation, coherence, and phase. These parameters are to be monitored and evaluated. Consistent with GALL AMP:
: 5. Monitoring        A. The neutron noise random fluctuation in the signals from the     Consistent with GALL AMP:      Yes  No and Trending        excore detectors are monitored, recorded, and analyzed to          Document(s) used to confirm Criteria:
Yes No Document(s) used to confirm Criteria:
identify changes in the beam mode natural frequency of the core support barrel and its direction of motion for the purpose of a timely determination of the need and urgency for a detailed inspection and examination of the reactor vessel internals hold-    Comment:
Comment: 4. Detection of Aging Effects A. Flow-induced vibration of the core support barrel will change the thickness of the downcomer annulus (water gap). This variation in the thickness will give rise to fluctuating changes in the neutron flux, as monitored by the excore neutron detectors. The natural frequencies and the amplitudes of the vibratory motion of the core barrel are related to the effective axial preload at the upper support flange of the core support barrel. Monitoring of the neutron noise signal obtained with the neutron flux detectors located around the external periphery of the reactor vessel provides detection of anomalous vibrational motion of the core support barrel, and hence significant loss of the axial preload. Decrease in the axial preload leads to decreases in the core support barrel beam mode frequency and an increase in the magnitude of the noise signal. The overall Consistent with GALL AMP:
down mechanism and mating component surfaces. These activities and analytical methodology are performed, and associated personnel are qualified, in accordance with site-controlled procedures and processes as indicated by vendor, industry, or regulatory guidance documents.
Yes No Document(s) used to confirm Criteria:  
The neutron noise monitoring program has three separate phases: a baseline phase, a surveillance phase, and a diagnostic phase. The baseline phase establishes the database to be used as a reference for developing limits and trends in the surveillance phase and to support data evaluation and interpretation in the diagnostic phase. During the baseline phase, data on the time history and DC level of each neutron flux detector and each cross-core detector pair are obtained.
From this database, the characteristic amplitudes and frequencies of the core barrel motion are extracted. The wide and narrow frequency bands with their associated normalized root mean square (NRMS) values are established. The ASME-OMS/G-1997, Part 5, recommends collecting the baseline data during the first fuel cycle that the neutron noise monitoring program is applied to an already operating plant. Whenever XI.M15 Neutron Noise Monitoring                                                        3
 
Program              Auditable GALL Criteria                                            Documentation of Audit Finding Element significant changes takes place for the core, reactor internals, or operating conditions, additional baseline data is obtained.
B. In the surveillance phase, routine neutron noise monitoring of  Consistent with GALL AMP:       Yes   No normal plant operations is performed over the life of the plant. Document(s) used to confirm Criteria:
The DC level and data for frequency analysis of each detector and two pair of cross-core detectors, may be collected.
Comparisons of the measured amplitude and frequency data, with limits established from the baseline data, are made. In        Comment:
using neutron noise monitoring, accounts are taken of the effect of core burn-up, decreasing boron concentration, changes in fuel management, and in-core contact with the reactor vessel mechanical snubbers, which may affect the neutron noise signatures. Proper allowances for these factors during the baseline and surveillance phases will help toward detecting loss of axial preload before the core barrel becomes sufficiently free to wear against the reactor vessel and will also reduce the need to invoke the diagnostic phase.
C. If the diagnostic phase becomes necessary, then evaluations      Consistent with GALL AMP:       Yes   No are carried out to establish whether any deviations from the        Document(s) used to confirm Criteria:
baseline data detected during the surveillance phase arises from core barrel motion due to loss of axial preload. The need and frequency of additional data collection on the time history and DC level of each neutron flux detector and each cross-core      Comment:
detector pair collection are guided by the results of these evaluations.
XI.M15 Neutron Noise Monitoring                                                        4


Program              Auditable GALL Criteria                                              Documentation of Audit Finding Element
: 6. Acceptance        A. If evaluation of the baseline data indicates normal operation    Consistent with GALL AMP:      Yes  No Criteria            for the applicable structure/component, the surveillance phase      Document(s) used to confirm Criteria:
may commence. If evaluation indicates anomalous behavior, the monitoring program enters the diagnostic phase.
Comment:
Comment:
XI.M15 Neutron Noise Monitoring 3 Program Element Auditable GALL Criteria Documentation of Audit Finding  effect of a decrease in the axial preload is to shift the neutron noise power spectrum toward larger amplitudes for the lower frequency region. 5. Monitoring and Trending A. The neutron noise random fluctuation in the signals from the excore detectors are monitored, recorded, and analyzed to identify changes in the beam mode natural frequency of the core support barrel and its direction of motion for the purpose of a timely determination of the need and urgency for a detailed inspection and examination of the reactor vessel internals hold-down mechanism and mating component surfaces. These activities and analytical methodology are performed, and associated personnel are qualified, in accordance with site-controlled procedures and processes as indicated by vendor, industry, or regulatory guidance documents. The neutron noise monitoring program has three separate phases: a baseline phase, a surveillance phase, and a diagnostic phase. The baseline phase establishes the database to be used as a reference for developing limits and trends in the surveillance phase and to support data evaluation and interpretation in the diagnostic phase. During the baseline phase, data on the time history and DC level of each neutron flux detector and each cross-core detector pair are obtained.
B. During the surveillance phase, if deviations from the baseline   Consistent with GALL AMP:       Yes   No fall within predetermined acceptable limits, the surveillance will  Document(s) used to confirm Criteria:
From this database, the characteristic amplitudes and frequencies of the core barrel motion are extracted. The wide and narrow frequency bands with their associated normalized root mean square (NRMS) values are established. The ASME-OMS/G-1997, Part 5, recommends collecting the baseline data during the first fuel cycle that the neutron noise monitoring program is applied to an already operating plant. Whenever Consistent with GALL AMP:
continue. Otherwise, the diagnostic phase will commence.
Yes No Document(s) used to confirm Criteria:  
 
Comment:
Comment:
XI.M15 Neutron Noise Monitoring 4 Program Element Auditable GALL Criteria Documentation of Audit Finding  significant changes takes place for the core, reactor internals, or operating conditions, additional baseline data is obtained. " B. In the surveillance phase, routine neutron noise monitoring of normal plant operations is performed over the life of the plant. The DC level and data for frequency analysis of each detector and two pair of cross-core detectors, may be collected. Comparisons of the measured amplitude and frequency data, with limits established from the baseline data, are made. In using neutron noise monitoring, accounts are taken of the effect of core burn-up, decreasing boron concentration, changes in fuel management, and in-core contact with the reactor vessel mechanical snubbers, which may affect the neutron noise signatures. Proper allowances for these factors during the baseline and surveillance phases will help toward detecting loss of axial preload before the core barrel becomes sufficiently free to wear against the reactor vessel and will also reduce the need to invoke the diagnostic phase. Consistent with GALL AMP:
: 7. Corrective        A. Initial results from the diagnostic phase of the program may     Consistent with GALL AMP:      Yes  No Actions              be used to determine whether there is a need to increase the         Document(s) used to confirm Criteria:
Yes No Document(s) used to confirm Criteria:  
minimum frequency with which the surveillance data are acquired. In addition, if necessary, corrective actions may be taken to change the type of data acquisition and analysis from that previously recommended for the surveillance part of the         Comment:
 
program. The data trends may be established to guide further data acquisition that may be needed to define future plant operation and/or program plans. As discussed in the appendix to this report, the staff finds the requirements of 10 CFR Part 50, Appendix B, acceptable to address the corrective actions.
Comment: " C. If the diagnostic phase becomes necessary, then evaluations are carried out to establish whether any deviations from the baseline data detected during the surveillance phase arises from core barrel motion due to loss of axial preload. The need and frequency of additional data collection on the time history and DC level of each neutron flux detector and each cross-core detector pair collection are guided by the results of these evaluations. Consistent with GALL AMP:
: 8.                  A. Site quality assurance (QA) procedures, review and approval      Consistent with GALL AMP:       Yes   No Confirmation        processes, and administrative controls are implemented in            Document(s) used to confirm Criteria:
Yes No Document(s) used to confirm Criteria:  
Process              accordance with the requirements of 10 CFR Part 50, Appendix B. As discussed in the appendix to this report, the staff finds the requirements of 10 CFR Part 50, Appendix B, acceptable to address the confirmation process and administrative controls.        Comment:
: 9.                  A. See Item 8, above.                                               Consistent with GALL AMP:       Yes   No Administrative                                                                            Document(s) used to confirm Criteria:
Controls XI.M15 Neutron Noise Monitoring                                                        5


Comment:
Program             Auditable GALL Criteria                                         Documentation of Audit Finding Element Comment:
XI.M15 Neutron Noise Monitoring 5 Program Element Auditable GALL Criteria Documentation of Audit Finding 6. Acceptance Criteria A. If evaluation of the baseline data indicates normal operation for the applicable structure/component, the surveillance phase may commence. If evaluation indicates anomalous behavior, the monitoring program enters the diagnostic phase. Consistent with GALL AMP:
: 10. Operating        A. The neutron noise monitoring program and procedures were      Consistent with GALL AMP:       Yes   No Experience          developed by the industry and published as a guide in ASME      Document(s) used to confirm Criteria:
Yes No Document(s) used to confirm Criteria:
OM-S/G-1997, Part 5, an American National Standard. This monitoring program and procedures have been effective in limited industry use for monitoring and detecting loss of core support barrel axial preload in PWR power plants.               Comment:
Comment: " B. During the surveillance phase, if deviations from the baseline fall within predetermined acceptable limits, the surveillance will continue. Otherwise, the diagnostic phase will commence. Consistent with GALL AMP:
XI.M15 Neutron Noise Monitoring                                                    6
Yes  No Document(s) used to confirm Criteria:
Comment: 7. Corrective Actions A. Initial results from the diagnostic phase of the program may be used to determine whether there is a need to increase the minimum frequency with which the surveillance data are acquired. In addition, if necessary, corrective actions may be taken to change the type of data acquisition and analysis from that previously recommended for the surveillance part of the program. The data trends may be established to guide further data acquisition that may be needed to define future plant operation and/or program plans. As discussed in the appendix to this report, the staff finds the requirements of 10 CFR Part 50, Appendix B, acceptable to address the corrective actions. Consistent with GALL AMP:
Yes  No Document(s) used to confirm Criteria:


Comment: 8.
EXCEPTIONS Item          Program Elements          LRA Exception Description  Basis for Accepting Exception  Documents Reviewed Number                                                                                              (Identifier, Para.# and/or Page #)
Confirmation Process A. Site quality assurance (QA) procedures, review and approval processes, and administrative controls are implemented in accordance with the requirements of 10 CFR Part 50, Appendix B. As discussed in the appendix to this report, the staff finds the requirements of 10 CFR Part 50, Appendix B, acceptable to address the confirmation process and administrative controls. Consistent with GALL AMP:
1.
Yes  No Document(s) used to confirm Criteria:
2.


Comment: 9.
ENHANCEMENTS Item          Program Elements          LRA Enhancement Description Basis for Accepting Enhancement Documents Reviewed Number                                                                                              (Identifier, Para.# and/or Page #)
Administrative Controls A. See Item 8, above. Consistent with GALL AMP:
1.
Yes  No Document(s) used to confirm Criteria:
2.


XI.M15 Neutron Noise Monitoring 6 Program Element Auditable GALL Criteria Documentation of Audit Finding Comment: 10. Operating Experience A. The neutron noise monitoring program and procedures were developed by the industry and published as a guide in ASME OM-S/G-1997, Part 5, an American National Standard. This monitoring program and procedures have been effective in limited industry use for monitoring and detecting loss of core support barrel axial preload in PWR power plants. Consistent with GALL AMP:
DOCUMENT REVIEWED DURING AUDIT Document Number                 Identifier (number)       Title                                                 Revision and/or Date 1.
Yes  No Document(s) used to confirm Criteria:
2.
Comment:
3.
XI.M15 Neutron Noise Monitoring 7 EXCEPTIONS  Item Number  Program Elements LRA Exception Description Basis for Accepting Exception Documents Reviewed  (Identifier, Para.# and/or Page #) 1. 2.    -
4.
ENHANCEMENTS Item Number Program Elements LRA Enhancement Description Basis for Accepting Enhancement Documents Reviewed  (Identifier, Para.# and/or Page #) 1. 2.    -
.
DOCUMENT REVIEWED D URING A UDIT  Document Number Identifier (number) Title Revision and/or Date 1. 2. 3. 4.   -.}}
XI.M15 Neutron Noise Monitoring                                                7}}

Revision as of 21:20, 23 November 2019

2006/03/22-GALL AMP: XI.M15, Neutron Noise Monitoring (Audit Worksheet GALL Report AMP)
ML060950370
Person / Time
Site: Vermont Yankee Entergy icon.png
Issue date: 03/22/2006
From: Morgan M
NRC/NRR/ADRO/DLR/RLRC
To:
Office of Nuclear Reactor Regulation
morgan M NRR/NRC/DLR/RLRC, 415-2232
Shared Package
ML060950189 List: ... further results
References
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Download: ML060950370 (10)
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Text

AUDIT WORKSHEET GALL REPORT AMP PLANT: ______________________________

LRA AMP: __________________________ REVIEWER: ______________________

GALL AMP: XI.M15, Neutron Noise Monitoring DATE: __________________________

Program Auditable GALL Criteria Documentation of Audit Finding Element Program A. The program relies on monitoring the excore neutron detector Consistent with GALL AMP: Yes No Description signals due to core motion to detect and monitor significant loss Document(s) used to confirm Criteria:

of axial preload at the core support barrels upper support flange in pressurized water reactors (PWRs). This inservice monitoring program is based on the recommendations from the American Society of Mechanical Engineers operation and maintenance Comment:

standards and guides (ASME OM-S/G)-1997, Part 5, Inservice Monitoring of Core Support Barrel Axial Preload in Pressurized Water Reactors Power Plants.

1. Scope of A. The program includes measures to monitor and detect loss of Consistent with GALL AMP: Yes No Program axial preload (loss of axial restraint) at the core support barrels Document(s) used to confirm Criteria:

upper support flange in PWRs. The loss of axial restraint may arise from long-term changes resulting from abnormal wear at the reactor vessel core barrel mating surface or short-term changes due to improper installation of the reactor internals. Comment The program also includes guidelines for further data acquisition that may be needed to define future plant operation and/or program plans in order to maintain the capability of the structure/components to perform the intended function.

2. Preventive A. The program is a monitoring/detection program that provides Consistent with GALL AMP: Yes No Actions early indication and detection of the onset of aging degradation Document(s) used to confirm Criteria:

of the core support barrelhold-down mechanism prior to a scheduled shutdown, thus reducing outage time and avoiding potential damage to the core support barrel and fuel assemblies. The AMP does not rely on preventive actions. Comment:

XI.M15 Neutron Noise Monitoring 1

Program Auditable GALL Criteria Documentation of Audit Finding Element

3. Parameters A. The program relies on the use of excore neutron detector Consistent with GALL AMP: Yes No Monitored/ signals to provide information on the conditions of the axial Document(s) used to confirm Criteria:

Inspected preload. The excore neutron flux signal is composed of a steady state, direct current (DC) component that arises from the neutron flux produced by the power operation of the reactor, as well as a fluctuating (noise-like) component. This fluctuating Comment:

signal arises from the core reactivity changes due to lateral core motion from the loss of axial preload. This core motion is mainly the result of beam mode vibration of the core support barrel.

Despite the fact that this beam mode vibration provides only a very weak neutron noise source, it may be reliably detected and identified through Fourier Analysis of the fluctuating signal component of the excore neutron flux signal. This signal component has the characteristics of having 180-degree shifts and a high degree of coherence between signals obtained from pairs of excore neutron detectors that are positioned on diametrically opposite sides of the core. The neutron noise signals are characterized by parameters, which include the auto correlation, cross correlation, coherence, and phase. These parameters are to be monitored and evaluated.

4. Detection of A. Flow-induced vibration of the core support barrel will change Consistent with GALL AMP: Yes No Aging Effects the thickness of the downcomer annulus (water gap). This Document(s) used to confirm Criteria:

variation in the thickness will give rise to fluctuating changes in the neutron flux, as monitored by the excore neutron detectors.

The natural frequencies and the amplitudes of the vibratory motion of the core barrel are related to the effective axial Comment:

preload at the upper support flange of the core support barrel.

Monitoring of the neutron noise signal obtained with the neutron flux detectors located around the external periphery of the reactor vessel provides detection of anomalous vibrational motion of the core support barrel, and hence significant loss of the axial preload. Decrease in the axial preload leads to decreases in the core support barrel beam mode frequency and an increase in the magnitude of the noise signal. The overall XI.M15 Neutron Noise Monitoring 2

Program Auditable GALL Criteria Documentation of Audit Finding Element effect of a decrease in the axial preload is to shift the neutron noise power spectrum toward larger amplitudes for the lower frequency region.

5. Monitoring A. The neutron noise random fluctuation in the signals from the Consistent with GALL AMP: Yes No and Trending excore detectors are monitored, recorded, and analyzed to Document(s) used to confirm Criteria:

identify changes in the beam mode natural frequency of the core support barrel and its direction of motion for the purpose of a timely determination of the need and urgency for a detailed inspection and examination of the reactor vessel internals hold- Comment:

down mechanism and mating component surfaces. These activities and analytical methodology are performed, and associated personnel are qualified, in accordance with site-controlled procedures and processes as indicated by vendor, industry, or regulatory guidance documents.

The neutron noise monitoring program has three separate phases: a baseline phase, a surveillance phase, and a diagnostic phase. The baseline phase establishes the database to be used as a reference for developing limits and trends in the surveillance phase and to support data evaluation and interpretation in the diagnostic phase. During the baseline phase, data on the time history and DC level of each neutron flux detector and each cross-core detector pair are obtained.

From this database, the characteristic amplitudes and frequencies of the core barrel motion are extracted. The wide and narrow frequency bands with their associated normalized root mean square (NRMS) values are established. The ASME-OMS/G-1997, Part 5, recommends collecting the baseline data during the first fuel cycle that the neutron noise monitoring program is applied to an already operating plant. Whenever XI.M15 Neutron Noise Monitoring 3

Program Auditable GALL Criteria Documentation of Audit Finding Element significant changes takes place for the core, reactor internals, or operating conditions, additional baseline data is obtained.

B. In the surveillance phase, routine neutron noise monitoring of Consistent with GALL AMP: Yes No normal plant operations is performed over the life of the plant. Document(s) used to confirm Criteria:

The DC level and data for frequency analysis of each detector and two pair of cross-core detectors, may be collected.

Comparisons of the measured amplitude and frequency data, with limits established from the baseline data, are made. In Comment:

using neutron noise monitoring, accounts are taken of the effect of core burn-up, decreasing boron concentration, changes in fuel management, and in-core contact with the reactor vessel mechanical snubbers, which may affect the neutron noise signatures. Proper allowances for these factors during the baseline and surveillance phases will help toward detecting loss of axial preload before the core barrel becomes sufficiently free to wear against the reactor vessel and will also reduce the need to invoke the diagnostic phase.

C. If the diagnostic phase becomes necessary, then evaluations Consistent with GALL AMP: Yes No are carried out to establish whether any deviations from the Document(s) used to confirm Criteria:

baseline data detected during the surveillance phase arises from core barrel motion due to loss of axial preload. The need and frequency of additional data collection on the time history and DC level of each neutron flux detector and each cross-core Comment:

detector pair collection are guided by the results of these evaluations.

XI.M15 Neutron Noise Monitoring 4

Program Auditable GALL Criteria Documentation of Audit Finding Element

6. Acceptance A. If evaluation of the baseline data indicates normal operation Consistent with GALL AMP: Yes No Criteria for the applicable structure/component, the surveillance phase Document(s) used to confirm Criteria:

may commence. If evaluation indicates anomalous behavior, the monitoring program enters the diagnostic phase.

Comment:

B. During the surveillance phase, if deviations from the baseline Consistent with GALL AMP: Yes No fall within predetermined acceptable limits, the surveillance will Document(s) used to confirm Criteria:

continue. Otherwise, the diagnostic phase will commence.

Comment:

7. Corrective A. Initial results from the diagnostic phase of the program may Consistent with GALL AMP: Yes No Actions be used to determine whether there is a need to increase the Document(s) used to confirm Criteria:

minimum frequency with which the surveillance data are acquired. In addition, if necessary, corrective actions may be taken to change the type of data acquisition and analysis from that previously recommended for the surveillance part of the Comment:

program. The data trends may be established to guide further data acquisition that may be needed to define future plant operation and/or program plans. As discussed in the appendix to this report, the staff finds the requirements of 10 CFR Part 50, Appendix B, acceptable to address the corrective actions.

8. A. Site quality assurance (QA) procedures, review and approval Consistent with GALL AMP: Yes No Confirmation processes, and administrative controls are implemented in Document(s) used to confirm Criteria:

Process accordance with the requirements of 10 CFR Part 50, Appendix B. As discussed in the appendix to this report, the staff finds the requirements of 10 CFR Part 50, Appendix B, acceptable to address the confirmation process and administrative controls. Comment:

9. A. See Item 8, above. Consistent with GALL AMP: Yes No Administrative Document(s) used to confirm Criteria:

Controls XI.M15 Neutron Noise Monitoring 5

Program Auditable GALL Criteria Documentation of Audit Finding Element Comment:

10. Operating A. The neutron noise monitoring program and procedures were Consistent with GALL AMP: Yes No Experience developed by the industry and published as a guide in ASME Document(s) used to confirm Criteria:

OM-S/G-1997, Part 5, an American National Standard. This monitoring program and procedures have been effective in limited industry use for monitoring and detecting loss of core support barrel axial preload in PWR power plants. Comment:

XI.M15 Neutron Noise Monitoring 6

EXCEPTIONS Item Program Elements LRA Exception Description Basis for Accepting Exception Documents Reviewed Number (Identifier, Para.# and/or Page #)

1.

2.

ENHANCEMENTS Item Program Elements LRA Enhancement Description Basis for Accepting Enhancement Documents Reviewed Number (Identifier, Para.# and/or Page #)

1.

2.

DOCUMENT REVIEWED DURING AUDIT Document Number Identifier (number) Title Revision and/or Date 1.

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XI.M15 Neutron Noise Monitoring 7

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