ML060880448

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GE Report, GE-NE-0000-0020-9436-R1-NP, Revision 1, Constellation Energy Group, Nine Mile Point Nuclear Station, Unit 2, 7/24/03 Instability Event, OPRM Performance Evaluation, March 2006.
ML060880448
Person / Time
Site: Nine Mile Point, PROJ0710  Constellation icon.png
Issue date: 03/31/2006
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General Electric Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
DRF 0000-0051-4286, MFN 06-089 GE-NE-0000-0020-9436-R1-NP, Rev 1
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ENCLOSURE 4 MFN 06-089 GE Report, GE-NE-0000-0020-9436-R1-NP, Revision 1, ConstellationEnergy Group, Nine Mile PointNuclearStation, Unit 2, 7/24/03 InstabilityEvent, OPRMPerformance Evaluation, March 2006 Non-Proprietary Version IMPORTANT NOTICE This is a non-proprietary version of GE-NE-0000-0020-9436-R1-P, which has the proprietary information removed. Portions of the enclosure that have been removed are indicated by an o-pen and closed bracket as shown here (( ))

GE Energy, Nuclear 1989 Little Orchard Road San Jose, CA 95125 GE-NE-0000-0020-9436-RI -N.P Revision 1 Class I DRF 0000-0051-4286 March 2006 NON-PROPRIETARY VERSION CONSTELLATION ENERGY GROUP NINE MILE POINT NUCLEAR STATION, UNIT 2 7/24/03 INSTABILITY EVENT OPRM PERFORMANCE EVALUATION

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version NON-PROPRIETARY INFORMATION NOTICE This is a non-proprietary version of the document GE-NE-0000-0020-9436-Rl-P, which has the proprietary information removed. Portions of the document that have been removed are indicated by an open and closed double brackets as shown here ((

IMPORTANT NOTICE REGARDING CONTENTS OF THIS REPORT Please Read Carefully The only undertakings of the General Electric Company (GE) respecting information in this document are contained in the contract between the customer and GE. Nothing contained in this document shall be construed as changing the contract. The use of this information by anyone other than the customer, or for any purpose other than that for which it is intended, is not authorized. With respect to any unauthorized use, GE makes no representation or warranty, express or implied, and assumes no liability as to the completeness, accuracy, or usefulness of the information contained in this document, or that its use may infringe privately owned rights.

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GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Table of Contents List of Tables/Figures ............................................... iii

1. BACKGROUND ............................................... 1
2. ASSESSMENT OBJECTIVES ............................................... 2
3. SYSTEM DESIGN AND KEY INPUTS ................................................ 3
4. EVALUATION AND RESULTS ............................................... 4 4.1 Oscillation Mode Determination ............................................... 4 4.2 Early Pre-Trip Alarm ............................................... 4 4.3 Final Pre-Trip Alarm ................................................ 4 4.4 Leading OPRM Cells and Detection Algorithm Performance ..................................... 5 4.5 Oscillation Periods, Growth Rates and Confirmation Counts ..................................... 6 4.6 SLMCPR Protection ............................................... 7 4.7 Size of the OPRM Trip Enabled Region ............................................... 7 4.8 Averaging Filter Cutoff Frequency ................................................ 7 4.9 Inoperable LPRMs/OPRMs ............................................... 7 4.10 Summary ............................................... 7
5. CONFIRMATION COUNT ASSESSMENT ............................................... 8 5.1 Simulated NMP-2 Signals ............................................... 9 5.2 Pilgrim Stable Data ............................................... 10 5.3 Processed NMP-2 Plant Data .............................................. 11
6. OPRM FIRMWARE LIMITATIONS ............................................... 12
7. CONCLUSIONS ............................................... 13
8. RECOMMENDATIONS .............................................. 14
9. REFERENCES ............................................... 15 ii

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version List of Tables/Figures Table 1. OPRM System Settings ............................................................. 16 Table 2. Maximum Counts for all NMP-2 OPRM Cells ..................................................... 17 Table 3. Maximum OPRM Cell P/A for all NMP-2 OPRM Cells ...................................... 18 Table 4. ((....................................... 19 Table 5..(( .19 Figure la. NMP-2 OPRM Channel 1 Assignment ............................................................ 20 Figure lb. NMP-2 OPRM Channel 2 Assignment ............................................................. 21 Figure Ic. NM P-2 OPRM Channel 3 Assignment ............................................................ 22 Figure Id. NMP-2 OPRM Channel 4 Assignment ............................................................ 23 Figure 2. Core-Wide Mode Demonstration ............................................................ 24 Figure 3a. Two Minute Pre-Trip Alarm (Cell 125) ............................................................. 25 Figure 3b. Two Minute Pre-Trip Alarm (Cell 301) ............................................................ 26 Figure 4a. Pre-Trip Alarm (Cell 214) ............................................................ 27 Figure 4b. Pre-Trip Alarm (Cell 111) ............................................................. 28 Figure 4c. Pre-Trip Alarm (Cell 323) ............................................................ 29 Figure 5a. Leading Cell Performance (Cell 125) ............................................................ 30 Figure 5b. Leading Cell Performance (Cell 327) ............................................................. 31 Figure Sc. Leading Cell Performance (Cell 428) ............................................................. 32 Figure 6. Leading OPRM Cells Oscillation Periods ............................................................ 33 Figure 7. Leading LPRM Cells Location (Marked in Yellow) ............................................ 34 Figure 8a. Cell 127 Performance ............................................................. 35 Figure 8b. Cell 201 Performance ............................................................ 36 Figure 9a. OPRM Cell 125 Simulated and Recorded Signals ............................................ 37 Figure 9b. OPRM Cell 201 Simulated and Recorded Signals ............................................ 38 Figure 10. Pilgrim Stable Data Filtering ............................................................ 39 Figure 1la. OPRM Cell 309 CC filtering Sensitivity with 50 msec Period Tolerance ...... 40 Figure 1lb. OPRM Cell 309 CC filtering Sensitivity with 100 msec Period Tolerance ....41 Figure 12. Number of Confirming Cells for OPRM Channels 1 and 2 .............................. 42 iii

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version

1. BACKGROUND Nine Mile Point-2 (NMP-2) has implemented Boiling Water Reactor Owners Group (BWROG) Long Term Stability Solution Option III, which is described in Reference 1.

Reload evaluation of the OPRM system setpoints has been performed in accordance with Reference 3 and the NMP-2 specific OPRM system setpoints are established.

The OPRM system monitors core thermal-hydraulic instabilities by real-time interrogation of OPRM cells, which are composed of closely packed LPRM detectors. The OPRM cell signals are analyzed by three separate detection algorithms that test for neutron flux oscillations. These algorithms are the Period Based Detection Algorithm (PBDA), the Amplitude Based Algorithm (ABA), and the Growth Rate Algorithm (GRA). Automatic protection is actuated if any one of the three algorithms meets its trip conditions.

However, only the PBDA is required to provide protection of the Safety Limit Minimum Critical Power Ratio (SLMCPR) for anticipated reactor instabilities. The other two algorithms are included as defense-in-depth.

On July 24, 2003 NMP-2 underwent a plant transient that included unplanned flow runback and recirculation pump downshift, eventually settling at about 45% rated power and 28% rated flow. At these conditions, a thermal-hydraulic core instability developed, subsequently terminating by an OPRM system initiated scram. The state condition just prior to the instability was in the upper left corner of the power/flow map, which may be susceptible to coupled thermal-hydraulic neutronic oscillations. The NMP-2 core loading consists of 764 bundles of GEl1 (a 9x9 fuel design). NMP-2 is licensed to operate within the Extended Load Line Limit Analysis (ELLLA) domain.

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GE-NE-0000-0020-943 6-RI -NP Non-Proprietary Version

2. ASSESSMENT OBJECTIVES The objectives of the NMP-2 July 24 instability event evaluation are to:
  • Document the Oscillation Power Range Monitor (OPRM) data extraction.
  • Analyze all OPRM cells.
  • Determine the characteristics ofthe reactor instability event (e.g., oscillation mode, oscillation frequency, period counts, oscillation amplitude).
  • Determine the algorithm that initiated the trip --- PBDA, ABA or GRA.
  • Assess the adequacy of the as-designed OPRM functions - alarm history, trip timing, behavior of OPRM channels, PBDA confirmation count setpoint, OPRM cell signal amplitude setpoint, OPRM comer frequency (also termed cutoff frequency), averaging filter cutoff frequency, size of OPRM trip enabled region, minimum/maximum oscillation period, Local Power Range Monitor (LPRM)/OPRM cell assignment, and inoperable LPRMs/OPRM cells.
  • Provide selected plots of OPRM cells Confirmation Count (CC), Growth Rate (GR),

Relative Signal (RS), and Oscillation Period (OP).

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GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version

3. SYSTEM DESIGN AND KEY INPUTS The NMP-2 OPRM system uses a 4P configuration with 4 LPRMs assigned to each OPRM cell. Figure la through Id illustrate the LPRM to OPRM assignment for the four channels, with 30 OPRM cells per channel. In this report, OPRM cells are designated as xyy, corresponding to OPRM cell yy of Channel x. Table 1 lists key parameters used by the OPRM system prior to the reactor trip and its assigned values.

The amplitude trip setpoint is the relative power level, or peak over average (P/A), at which the OPRM cell generates a trip signal, provided the required number of oscillation period confirmation counts (CC) has been reached. Two conditions must be met for the same OPRM cell in an OPRM channel to result in a PBDA-based channel trip:

1. The CC reaches or exceeds the CC setpoint (14 for NMP-2).
2. The cell signal P/A reaches or exceeds the OPRM trip amplitude setpoint (1.12 for NMP-2).

((

)) The MVD data includes the following information, available for all OPRM cells:

  • Relative signal
  • Oscillation period confirmation count
  • Growth rate (provided by the firmware only when the relative amplitude reaches and exceeds 1.1)
  • Time-averaged base period.

((

))

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GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version

4. EVALUATION AND RESULTS The OPRM performance evaluation includes identification of:
  • Oscillation mode - core-wide or regional
  • Early Pre-Trip Alarm
  • Final Pre-Trip Alarm
  • Leading OPRM cells and detection algorithm that caused channel trips
  • Oscillation periods, approximate growth rates, and confirmation counts
  • SLMCPR protection during the event
  • Size of the OPRM trip enabled region
  • Averaging filter cutoff frequency

4.1 Oscillation Mode Determination The relative signals for four selected OPRM cells from each core quadrant are shown in Figure 2. For these four nearly symmetric OPRM cells (Cells 305, 308, 322 and 325), the oscillations are all in phase, indicating that the oscillations are in the fundamental core-wide mode.

4.2 Early Pre-Trip Alarm Based on individual CC plots, there were a few alarms during the event. The plant reported a pre-trip alarm approximately 2 minutes prior to the OPRM system trip. This is consistent with the MVD data traces indicating that OPRM channels 1 and 3 had alarms at that time.

OPRM Cell 125 reached the alarm CC setpoint of 12, causing a pre-trip alarm in Channel

1. Several OPRM cells in Channel 3 (Cells 301, 322 and 327) also exceeded the alarm setpoint. Figures 3a and 3b show the RS, OP and CC for Cells 125 and 301. The corresponding P/A however was low (1.02) at this time for these leading OPRM cells.

Even though the relative signal has a small amplitude (+/- 0.02), the coherence of the signal for these OPRM cells resulted in discemable alarms.

4.3 Final Pre-Trip Alarm The plant reported another set of pre-trip alarms about 15 seconds prior to the scram. This is consistent with the MVD data traces indicating that several of the Channel 2 OPRM 4

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version cells (214, 213 or 208) reached or exceeded the alarm CC setpoint about 13 seconds before the actual trip. Cell 111 reached the alarm setpoint, causing the alarm in Channel 1.

Similarly, Cell 323 generated a pre-trip alarm in Channel 3. Hence, the Channels 1, 2 and 3 alarms were consistent with the plant data. Figures 4a through 4c show the CC, OP, and RS of selected leading cells (Cells 214, 111, and 323, respectively) that caused the alarms.

4.4 Leading OPRM Cells and Detection Algorithm Performance Table 2 lists the maximum CC from the MVD recorded data for all OPRM cells. Of the OPRM cells that exceeded the CC trip setpoint (i.e., 14), the relative signal is examined to ensure that the P/A setpoint is also reached and the leading OPRM cells that caused the channel trip are identified.

Figures 5a through 5c identify the leading OPRM cells in three of the OPRM channels (Cells 125, 327 and 428), respectively. With a two-out-of-four logic, only two OPRM channel trips are required for a reactor trip. The sequence in which the confirming OPRM cells (i.e., exceeding the CC setpoint) reach the amplitude setpoint was:

1. Cell 428
2. Cells 327 and 125 (almost simultaneously)

This trip history is consistent with the plant history, which showed that Channel 4 tripped first, followed shortly by Channels 1 and 3. Hence the PBDA logic caused the reactor trip based on OPRM cells 428, 327 and 125. The other two defense-in-depth algorithms (ABA and GRA) did not generate a trip signal since the growth rate did not exceed 1.3 nor the relative amplitude exceeded 1.30. It is concluded therefore, that the OPRM system trip was generated by the PBDA algorithm and that the OPRM system provided its intended protection.

Table 3 lists the maximum P/A amplitude for each OPRM cell for the entire event. Even though the OPRM P/A setpoint is set at 1.12, Table 3 indicates that a few OPRM cells exceeded this value, up to a maximum P/A value of 1.14 prior to the trip. The PBDA algorithm is expected to first reach the CC setpoint and subsequently reach the amplitude setpoint, resulting then in a trip signal. Cell 428 tripped as expected, reaching the CC setpoint prior to the amplitude setpoint. However, Cells 327 and 125 did not trip as expected since at the time the P/A reached the amplitude setpoint of 1.12, the CC was below the CC setpoint. As a result, the CC setpoint was reached only after the P/A reached 1.13 (the 14 confirmation occurred at the next valley). The next peak, which occurred prior to the power suppression, reached an amplitude of 1.14. This 0.01 amplitude overshoot is recognized by the HCOM methodology. However, exceeding the 1.12 setpoint prior to the trip is not expected.

In general, as the oscillation magnitude grows it overcomes the interference from the noise and allows fewer resets.

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GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version 4.5 Oscillation Periods, Growth Rates and Confirmation Counts The core-wide mode reactor oscillations were initiated approximately 40 seconds prior to the reactor trip. At the instability threshold, the oscillation period tended to be less coherent. However, as the oscillation developed, with a relatively low growth rate (GR < 1.10), they become periodic, resulting in an average period of about 1.78 seconds, which is within the expected range of reactor oscillations.

For the three leading OPRM cells (depicted in Figures Sa 5b and 5c), the time-averaged oscillation period at the time of the trip is between 1.77 to 1.78 seconds (Figure 6), which is within the expected period of 1.0 to 3.0 seconds. Or in terms of oscillation frequency, the oscillation frequency is about 0.56 Hz, which is well within the expected range of oscillation (0.3 to 0.7 Hz). It is noted that the 10 msec spread in the four leading OPRM cells time-averaged period at the time of the trip is well within the signal sampling rate of 46 msec.

An analysis of all the OPRM cell confirmation counts (120 cells in total) indicates numerous period confirmation count resets. Very few OPRM cells exceeded the CC setpoint of 14 and only three OPRM cells (125, 327, 428) met the relative amplitude and CC setpoints at the time of the OPRM system trip signal. At the time of the trip, a total of five OPRM cells reached or exceeded the CC setpoint.

In a number of OPRM cells the counts were reset just prior to the reactor trip, which is unexpected. Figures 8a and 8b show two examples of OPRM cells that had resets prior to the actual scram. These CC resets were due to either period tolerance or Tmin reset.

Cell 127 exhibits a period confirmation reset shortly before the trip. As the oscillations are fully developed, this reset is not expected. Cell 201 is close to the core periphery and includes two D Level LPRMs. Even though resets are expected, this cell lacks a coherent period altogether.

The GR is provided by the firmware only when the relative amplitude reaches and exceeds 1.1. Due to the mild oscillations, the GR slightly exceeds 1.10 for the leading OPRn cells.

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GE-NE-0000-0020-9436-R1 -NP Non-Proprietary Version 4.6 SLMCPR Protection The OPRM setpoint of 1.12 provides adequate protection of the SLMCPR based on the margin estimated from the final Minimum Critical Power Ratio (MCPR). ((

)) Hence the SLMCPR has been protected during the instability event.

It is noted that if the reactor had been operating at the OLMCPR prior to the event, the reactor would have ended very close to the SLMCPR had a regional oscillation developed.

4.7 Size of the OPRM Trip Enabled Region The OPRM trip enabled region comprises a region > 29% rated power and

< 62.5% rated flow. This is deemed adequate for NMP-2 C9 operation since the instability event started at a power/flow point significantly away from the Armed Region boundaries.

4.8 Averaging Filter Cutoff Frequency This assessment could not be completed due to the lack of raw LPRM signals. The use of a 0.167 Hz cutoff frequency is deemed adequate per Reference 8.

4.9 Inoperable LPRMs/OPRMs This aspect is not evaluated in this report since the number of failed OPRM cells is very low. The use of 2 as the minimum number of LPRMs per operable OPRM cell is not evaluated since the NMP-2 specific assignment is based on 4 LPRMs per OPRM cell.

4.10 Summary The NMP-2 instability event was identified as a core-wide mode oscillation and was terminated by the PBDA. The PBDA did not perform as expected since the OPRM P/A slightly exceeded the amplitude trip setpoint. In addition, most of the OPRM cells did not perform as expected, exhibiting numerous CC resets. These resets were not expected and their source must be understood and addressed to ensure PBDA effectiveness. In addition, some minor inconsistencies relative to the PBDA expected performance in establishing the base period, successive confirmation count, and P/A values at identified peaks were observed. The next sections address these concerns.

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GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version

5. CONFIRMATION COUNT ASSESSMENT As indicated in the previous section, most of the OPRM cells did not perform as expected, exhibiting numerous CC resets. These resets were not expected and their source must be understood and addressed to ensure PBDA effectiveness. Close examination of the CC resets revealed that some were as a result of residual high frequency components violating the Tmin criterion (i.e., time intervals between successive peaks or valleys shorter than Tmin). Many of the CC resets were as a result of large variations in the measured period, violating the period tolerance criterion.

GE initiated an internal study to investigate these CC resets and identified two key concerns:

1. The second-order Butterworth filter with a setting of 3 Hz cutoff frequency is ineffective in removing some residual high-frequency noise from the oscillation signal, and
2. The use of a period tolerance similar to the OPRM sampling time.

Three different studies were performed to investigate the CC reset concern and are summarized in this section:

)) GE recommended that a period tolerance of not less then 100 msec be used.

The use of a period tolerance similar to the OPRM sampling time in conjunction with the observed filtering deficiency may further exacerbate the CC reset issue based on the assessment below.

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GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version 5.1 Simulated NMP-2 Signals The OPRM system uses a second-order Butterworth digital filter with a specified cutoff (or comer) frequency. The cutoff frequency is an adjustable parameter of the PBDA algorithm with permissible values ranging from I to 3 Hz in increments of 0.1 Hz. For NMP-2, a 3 Hz comer frequency was used.

As indicated earlier, ((

Figures 9a and 9b show that the residual high frequency noise for the simulated 3 Hz filtered signals and the relative plant signals agree relatively well for Cells 125 and 201, respectively.

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GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version 5.2 Pilgrim Stable Data The conclusion of the previous section is based on simulated data. ((

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GE-NE-0000-0020-9436-R I -NP Non-Proprietary Version 5.3 Processed NMP-2 Plant Data

[I

))

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GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version

6. OPRM FIRMWARE LIMITATIONS

))

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GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version

7. CONCLUSIONS The following conclusions can be drawn from the NMP-2 OPRM instability event data analysis:
1. The oscillation mode is core-wide.
2. The reactor was tripped by the PBDA; however, the OPRM P/A slightly exceeded the cycle-specific amplitude setpoint of 1.12. The PBDA did not trip as expected.
3. The Tmin and Tmax settings of 1.2 and 3.0 seconds, respectively, were appropriate for the specific NMP-2 configuration.
4. The use of a 0.167 Hz cutoff frequency averaging filter is adequate for this event.
5. Based on the MCPR assessment in the previous ODYSY report, the OPRM system CC and amplitude setpoints are adequate.
6. The design of 4 LPRMs per OPRM cell is adequate for this application since the OPRM cell signals do not exhibit any abnormal behavior.
7. As the oscillation magnitude grows it overcomes the interference from the noise and allows fewer resets.
8. There were numerous unexpected CC resets in the PBDA.

The NMP-2 instability event did not produce any safety hazard and the SLMCPR was protected by the Option III OPRM system. Due to robust OPRM design, it is possible that the settings currently in use and allowed by licensing documentation could provide SLMCPR protection for other instability events. However, GENE cannot confirm that performance of the OPRM with all conditioning filter and period tolerance settings currently in use or allowed by licensing documentation will not lead to a condition where the SLMCPR could be violated for an anticipated instability event in operating plants implementing Option III. Based on these results, it is concluded that this is a reportable condition under 10CFR part 21.

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GE-NE-0000-0020-9436-R1 -NP Non-Proprietary Version

8. RECOMMENDATIONS The following recommendations are made to ensure the OPRM system performance is adequate and robust:
1. Selection of 1 Hz for the condition filter cutoff frequency is sufficient to remove high frequency noise from the OPRM cell signal to minimize SCC rests for a coherent oscillation. Analysis by GENE does not support use of a conditioning filter cutoff frequency higher than 1 Hz. Parameter values beyond the recommended value may be appropriate based on further evaluations or plant-specific demonstration.
2. Selection of the period tolerance at 100 msec or larger is sufficient to avoid SCC resets due to normal signal period variations, filtering residual effects that may distort the signal characteristic at peaks/valleys, and software digital processing inaccuracies. Analysis by GENE does not support use of a period tolerance lower than 100 msec. Parameter values beyond the recommended value may be appropriate based on further evaluations or plant-specific demonstration.
3. An alarm based on high CC in a single OPRM cell may result in ambiguous indication since it could be attributed either to an actual reduction in stability margin or it could have been generated as a result of the random nature of the OPRM signal. Therefore, it may be appropriate to increase the alarm CC setpoint or disable the alarm if it continues to provide ambiguous indication.t.
4. The PBDA period confirmation adjustable variables should not be changed (i.e.,

"tuned") in such a way as to limit the number of alarms, without adequate consideration of the impact of the change on ability of the PBDA to detect an actual instability event. If only a single value of each adjustable variable is allowed based on available justification, then a tuning procedure for the PBDA period confirmation adjustable variables is not applicable.

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GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version

9. REFERENCES
1. NEDO-31960-A, "BWR Owner's Group Long-Term Stability Solutions Licensing Methodology," November 1995.
2. Not Used.
3. NEDO-32465-A, "Reactor Stability Detect and Suppress Solutions Licensing Basis Methodology for Reload Application," August 1996.
4. Not Used.
5. Not Used.
6. Not Used.
7. Not Used.
8. Safety Communications SC02-09, Stability Option III Trip Adequacy for Instability During fast Transients, July 26, 2002.

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GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Table 1. OPRM System Settings Parameter Setting Corner or cutoff 3 Hz frequency Period tolerance 50 msec OPRM P/A setpoint 1.12 OPRM CC alarm setpoint 12 OPRM CC trip setpoint 14 Tmin (Minimum 1.2 oscillation period check)

Tmax (Maximum 3.0 oscillation period check)

OPRM trip enabled > 29% rated power, region size < 62.5% rated flow Min LPRMs per 2 Operable OPRM cell Averaging filter cutoff 0.167 Hz*

frequency Reactor Protection Two out of four System (RPS) trip logic

  • This was referred to as an averaging time constant of 0.95 second elsewhere. This is misleading since a second order Butterworth filter with the specified cutoff frequency is used.

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GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Table 2. Maximum Counts for all NMP-2 OPRM Cells OPRM Cell Channel 1 Channel 2 Channel 3 Channel 4 1 3 2 15 4 2 2 2 255 (Inop) 5 3 6 6 2 4 4 4 10 12 3 5 3 3 5 4 6 4 3 3 11 7 4 6 4 5 8 7 13 8 5 9 2 8 6 9 10 2 4 4 5 11 13 3 3 8 12 7 3 9 3 13 3 15 S 4 14 13 15 4 8 15 5 3 4 7 16 4 20 5 7 17 4 8 13 3 18 6 2 11 9 19 5 2 3 11 20 6 7 3 8 21 8 3 3 4 22 6 3 16 2 23 4 9 21 4 24 4 5 3 5 25 15 3 4 4 26 5 4 4 4 27 11 5 15 5 28 5 4 3 19 29 3 7 2 3 30 6 8 4 5 17

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Table 3. Maximum OPRM Cell P/A for all NMP-2 OPRM Cells OPRM Cell Channel 1 Channel 2 -Channel 3 Channel 4 I 1.11 1.10 1.12 1.11 2 1.11 1.13 NA (Inop) 1.11 3 1.13 1.14 1.11 1.12 4 1.11 1.11 1.13 1.10 5 1.10 1.10 1.11 1.11 6 1.11 1.12 1.09 1.12 7 1.12 1.13 1.13 1.11 8 1.13 1.13 1.14 1.11 9 1.10 1.11 1.12 1.11 10 1.09 1.11 1.11 1.11 11 1.12 1.11 1.10 1.11 12 1.11 1.11 1.12 1.11 13 1.11 1.14 1.13 1.12 14 1.13 1.14 1.12 1.12 15 1.11 1.11 1.10 1.12 16 1.10 1.11 1.11 1.10 17 1.10 1.11 1.11 1.10 18 1.11 1.10 1.11 1.11 19 1.12 1.12 1.11 1.13 20 1.14 1.13 1.12 1.12 21 1.12 1.10 1.09 1.10 22 1.11 1.09 1.11 1.10 23 1.10 1.11 1.11 1.11 24 1.12 1.12 1.10 1.11 25 1.14 1.11 1.11 1.12 26 1.14 1.10 1.13 1.11 27 1.11 1.10 1.12 1.10 28 1.12 1.11 1.10 1.12 29 1.12 1.13 1.12 1.11 30 1.13 1.12 1.13 1.11 18

GE-NE-0000-0020-9436-R1 -NP Non-Proprietary Version Table 4. ((

4 4 1 4 4 1 1 1 4 4 4 +

))

Table 5. ((

11 19

GE-NE-0000-0020-9436-Ri -NP Non-Proprietary Version Figure la. NMP-2 OPRM Channel 1 Assignment 20

GE-NE-0000-0020-943 6-RI -NP Non-Proprietary Version Figure lb. NMP-2 OPRM Channel 2 Assignment 21

GE-NE-0000-0020-943 6-Ri -NP Non-Proprietary Version Figure Ic. NMP-2 OPRM Channel 3 Assignment 22

GE-NE-0000-0020-9436-Ri -NP Non-Proprietary Version Figure 1d. NMP-2 OPRM Channel 4 Assignment 23

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Figure 2. Core-Wide Mode Demonstration OPRM Cell RS 1.4

- F--

Ch 305 Ch 322

.* -- CH 308 1.2 Ch 325 1 A A_A A

, 0.8 x 0.6 0.4 II I 0.2 0

02::44.2 02:52.8 03 :01.4 time + 5 minute 24

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Figure 3a. Two Minute Pre-Trip Alarm (Cell 125)

Cd 125 MM9 MR$l M42 MS11 elis AddI 01:1 0124 25

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Figure 3b. Two Minute Pre-Trip Alarm (Cell 301)

Cd 301 to U

CI-M I-ca2 LP I air, r rp, .,

-Ivv v vv v u v

/2 _l ta M3416 M42 M51J

. lifil C.II OtI?.1 t4 26

1:____ _

GE-NE-0000-0020-943 6-RI -NP Non-Proprietary Version Figure 4a. Pre-Trip Alarm (Cell 214)

Cell 214

-RS tzCC/2 02:26.9 02:35.5 02:44.2 02:52.8 03:01.4 27

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Figure 4b. Pre-Trip Alarm (Cell 111)

Cell 111

-RS

- CC/20 02:26.9 02:35.5 02:44.2 02:52.8 03:01 A 28

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Figure 4c. Pre-Trip Alarm (Cell 323)

Cell 323 1.8 - I 1.6 1.4 12 a

-RS

- CC/20

-OP 0.8 0.6.

0.4-0 02:26.9 02:35.5 02:44.2 02:52.8 03:01.4 29

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Figure 5a. Leading Cell Performance (Cell 125)

Cell 125

-RS1

-CCt2C J--G 02:26.9 02:35.5 02:44.2 02:52.8 03:01.4 30

GE-NE-0000-0020-943 6-Ri -NP Non-Proprietary Version Figure 5b. Leading Cell Performance (Cell 327)

Cell 327 1.2 -

0.8 0-RCH 0.6 - ~O 02:26.9 02:35.5 02:44.2 02:52.8 03:01.4 31

GE-NE-0000-0020-9436-Ri -NP Non-Proprietary Version Figure 5c. Leading Cell Performance (Cell 428)

Cell 428

-RS

- CC/20

-GR oil XI l I,, I .I 02:26.9 02:44.2 03:01A 32

GE-NE-0000-0020-9436-Ri -NP Non-Proprietary Version Figure 6. Leading OPRM Cells Oscillation Periods

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3]

33

GE-NE-0000-0020-9436-Ri -NP Non-Proprietary Version Figure 7. Leading LPRM Cells Location (Marked in Yellow) 34

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Figure 8a. Cell 127 Performance Cell 127

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M -GR 02:26.9 02:35.5 02:442 02:52.8 03:01A 35

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Figure 8b. Cell 201 Performance Cell 201 12 I

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o I n FlnF ru 02:26.9 02:35.5 02:44.2 02:52.8 03:01.4 36

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Figure 9a. OPRM Cell 125 Simulated and Recorded Signals

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37

GE-NE-0000-0020-9436-Ri -NP Non-Proprietary Version Figure 9b. OPRM Cell 201 Simulated and Recorded Signals 38

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Figure 10. Pilgrim Stable Data Filtering 39

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Figure 11 a. OPRM Cell 309 CC filtering Sensitivity with 50 msec Period Tolerance

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40

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Figure 11 b. OPRM Cell 309 CC filtering Sensitivity with 100 msec Period Tolerance Er (3)))

41

GE-NE-0000-0020-9436-RI -NP Non-Proprietary Version Figure 12. Number of Confirming Cells for OPRM Channels 1 and 2 42

ENCLOSURE 1 MFN 06-089 GE Report, GE-NE-0000-0041-0403-RI-P, Revision 1, First Energy Corp, Perry Nuclear Power Plant, 12/23/04 Instability Event, OPRMPerformance Evaluation, March 2006 IMPORTANT NOTICE GE Proprietary Information PROPRIETARY INFORMATION NOTICE This enclosure contains proprietary information of the General Electric Company (GE) and is furnished in confidence solely for the purpose(s) stated in the transmittal letter. No other use, direct or indirect, of the document or the information it contains is authorized. Furnishing this enclosure does not convey any license, express or implied, to use any patented invention or, except as specified above, any proprietary information of GE disclosed herein or any right to publish or make copies of the enclosure without prior written permission of GE. The header of each page in this enclosure carries the notation "GE Proprietary Information."

GE proprietary information is identified by a double underline inside double square brackets. In each case, the superscript notation 3 ) refers to Paragraph (3) of the affidavit provided in , which documents the basis for the proprietary determination. ((This sentence is an example. t 3 ))) Specific information that is not so marked is not GE proprietary.

ENCLOSURE 2 MFN 06-089 GE Report, GE-NE-0000-0020-9436-R1-P, Revision 1, Constellation Energy Group, Nine Mile Point Nuclear Station, Unit 2, 7/24/03 Instability Event, OPRM Performance Evaluation, March 2006 IMPORTANT NOTICE GE Proprietary Information PROPRIETARY INFORMATION NOTICE This enclosure contains proprietary information of the General Electric Company (GE) and is furnished in confidence solely for the purpose(s) stated in the transmittal letter. No other use, direct or indirect, of the document or the information it contains is authorized. Furnishing this enclosure does not convey any license, express or implied, to use any patented invention or, except as specified above, any proprietary information of GE disclosed herein or any right to publish or make copies of the enclosure without prior written permission of GE. The header of each page in this enclosure carries the notation "GE Proprietary Information."

GE proprietary information is identified by a double underline inside double square brackets. In each case, the superscript notation1 31 refers to Paragraph (3) of the affidavit provided in , which documents the basis for the proprietary determination. ((This sentence is am example.1 31 1] Specific information that is not so marked is not GE proprietary.

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