Event Notification Report for October 01, 2002
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
09/30/2002 - 10/01/2002
EVENT NUMBERS
39234392353923639244
Power Reactor
Event Number: 39234
Facility: MCGUIRE
Region: 2 State: NC
Unit: [] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: TIM JOHNSON
HQ OPS Officer: MIKE NORRIS
Region: 2 State: NC
Unit: [] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: TIM JOHNSON
HQ OPS Officer: MIKE NORRIS
Notification Date: 10/01/2002
Notification Time: 16:56 [ET]
Event Date: 10/01/2002
Event Time: 09:42 [EDT]
Last Update Date: 10/01/2002
Notification Time: 16:56 [ET]
Event Date: 10/01/2002
Event Time: 09:42 [EDT]
Last Update Date: 10/01/2002
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
10 CFR Section:
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
JAY HENSON (R2)
JAY HENSON (R2)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | N | N | 0 | Refueling | 0 | Refueling |
VALID SPECIFIED SYSTEM ACTUATION DURING TESTING ON ENGINEERED SAFETY FEATURES
"Station was conducting ESF testing on the 1B train with the 1B Diesel Generator aligned to the 1B essential bus. While re-aligning from the test alignment, the 1B emergency breaker tripped open due to a problem with the Cutler-Hammer control switch. A valid blackout signal was sensed on the 1B bus. The 1B emergency breaker immediately re-closed and the 1B essential bus was re-energized from the 1B Diesel Generator. Switch repair is in progress."
The Licensee has notified the NRC Resident Inspector.
"Station was conducting ESF testing on the 1B train with the 1B Diesel Generator aligned to the 1B essential bus. While re-aligning from the test alignment, the 1B emergency breaker tripped open due to a problem with the Cutler-Hammer control switch. A valid blackout signal was sensed on the 1B bus. The 1B emergency breaker immediately re-closed and the 1B essential bus was re-energized from the 1B Diesel Generator. Switch repair is in progress."
The Licensee has notified the NRC Resident Inspector.
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
Power Reactor
Event Number: 39235
Facility: WOLF CREEK
Region: 4 State: KS
Unit: [1] [] []
RX Type: [1] W-4-LP
NRC Notified By: STEVEN A. HENRY
HQ OPS Officer: MIKE NORRIS
Region: 4 State: KS
Unit: [1] [] []
RX Type: [1] W-4-LP
NRC Notified By: STEVEN A. HENRY
HQ OPS Officer: MIKE NORRIS
Notification Date: 10/01/2002
Notification Time: 17:44 [ET]
Event Date: 10/01/2002
Event Time: 08:45 [CDT]
Last Update Date: 10/31/2002
Notification Time: 17:44 [ET]
Event Date: 10/01/2002
Event Time: 08:45 [CDT]
Last Update Date: 10/31/2002
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(ii)(B) - UNANALYZED CONDITION
10 CFR Section:
50.72(b)(3)(ii)(B) - UNANALYZED CONDITION
Person (Organization):
KRISS KENNEDY (R4)
KRISS KENNEDY (R4)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
UNANALYZED CONDITION RELATING TO CONTROL ROOM EVACUATION
"On October 1 2002, conditions were discovered that if an evacuation of the Wolf Creek Generation Station (WCGS) control room were required, due to a fire, necessary steps could not be completed within committed time requirements. The station is in Mode 1, at 100% power.
"During a timed walk down of procedure OFN RP-017, 'Control Room Evacuation,' it was identified that operators did not complete Phase A actions of the procedure in the committed five minutes. Phase A provides that control of the plant will be established at the Auxiliary Shutdown Panel (ASP) and isolation of required instrumentation and other devices on the ASP will be accomplished. Phase A was performed in approximately 8 minutes. This does not meet our commitment to 10 CFR 50 Appendix R as reflected in the WCGS Fire Protection Plan. The effect of additional time to complete Phase A of the control room evacuation is being further analyzed to determine the safety significance.
"Based on the guidance provided in NUREG 1022 Revision 2, this situation meets the criterion of 10CFR50.72(b)(3)(ii)(B) for an 8-hour ENS notification, as it relates to being in an unanalyzed condition."
The Licensee has implemented compensatory measures at 1900 CDT, 10/1/02.
The licensee has notified the NRC Resident Inspector
****RETRACTION JEFF ISCH TO MIKE NORRIS 1429 ET 10/31/02****
"BASIS FOR RETRACTION:
"A safety significance evaluation was performed for the condition described above and it was determined that the circumstances do not constitute a significant reduction in plant safety. This conclusion is based on the results of simulator exercises that concluded that the 5 minute completion time was conservative and that the actions needed to place the plant in a safe condition could be performed within 8 minutes. The evaluation provides reasonable assurance that operator activities taken to complete Phase A actions within a 7 to 8 minute period does not result in consequences of safety significance. This conclusion is further validated by comparing the results with bounding conditions contained in a Westinghouse WCAP report for a similar condition involving a failed open power operated relief valve (PORV), as well as an engineering evaluation previously performed for both PORVs spuriously opening due to a fire. Therefore, per NUREG 1022, this condition is not an unanalyzed condition that significantly degrades plant safety and is not required to be reported in accordance with 10CFR50.72(b)(3)(ii)(B)."
The Licensee has notified the NRC Resident Inspector.
"On October 1 2002, conditions were discovered that if an evacuation of the Wolf Creek Generation Station (WCGS) control room were required, due to a fire, necessary steps could not be completed within committed time requirements. The station is in Mode 1, at 100% power.
"During a timed walk down of procedure OFN RP-017, 'Control Room Evacuation,' it was identified that operators did not complete Phase A actions of the procedure in the committed five minutes. Phase A provides that control of the plant will be established at the Auxiliary Shutdown Panel (ASP) and isolation of required instrumentation and other devices on the ASP will be accomplished. Phase A was performed in approximately 8 minutes. This does not meet our commitment to 10 CFR 50 Appendix R as reflected in the WCGS Fire Protection Plan. The effect of additional time to complete Phase A of the control room evacuation is being further analyzed to determine the safety significance.
"Based on the guidance provided in NUREG 1022 Revision 2, this situation meets the criterion of 10CFR50.72(b)(3)(ii)(B) for an 8-hour ENS notification, as it relates to being in an unanalyzed condition."
The Licensee has implemented compensatory measures at 1900 CDT, 10/1/02.
The licensee has notified the NRC Resident Inspector
****RETRACTION JEFF ISCH TO MIKE NORRIS 1429 ET 10/31/02****
"BASIS FOR RETRACTION:
"A safety significance evaluation was performed for the condition described above and it was determined that the circumstances do not constitute a significant reduction in plant safety. This conclusion is based on the results of simulator exercises that concluded that the 5 minute completion time was conservative and that the actions needed to place the plant in a safe condition could be performed within 8 minutes. The evaluation provides reasonable assurance that operator activities taken to complete Phase A actions within a 7 to 8 minute period does not result in consequences of safety significance. This conclusion is further validated by comparing the results with bounding conditions contained in a Westinghouse WCAP report for a similar condition involving a failed open power operated relief valve (PORV), as well as an engineering evaluation previously performed for both PORVs spuriously opening due to a fire. Therefore, per NUREG 1022, this condition is not an unanalyzed condition that significantly degrades plant safety and is not required to be reported in accordance with 10CFR50.72(b)(3)(ii)(B)."
The Licensee has notified the NRC Resident Inspector.
General Information or Other
Event Number: 39236
Rep Org: GENERAL ELECTRIC COMPANY
Licensee: GENERAL ELECTRIC COMPANY
Region: 4
City: San Jose State: CA
County:
License #:
Agreement: Y
Docket:
NRC Notified By: JASON S. POST
HQ OPS Officer: MIKE NORRIS
Licensee: GENERAL ELECTRIC COMPANY
Region: 4
City: San Jose State: CA
County:
License #:
Agreement: Y
Docket:
NRC Notified By: JASON S. POST
HQ OPS Officer: MIKE NORRIS
Notification Date: 10/01/2002
Notification Time: 20:24 [ET]
Event Date: 10/01/2002
Event Time: 00:00 [PDT]
Last Update Date: 11/18/2002
Notification Time: 20:24 [ET]
Event Date: 10/01/2002
Event Time: 00:00 [PDT]
Last Update Date: 11/18/2002
Emergency Class: NON EMERGENCY
10 CFR Section:
21.21 - UNSPECIFIED PARAGRAPH
10 CFR Section:
21.21 - UNSPECIFIED PARAGRAPH
Person (Organization):
PETE ESELGROTH (R1)
JAY HENSON (R2)
SONIA BURGESS (R3)
KRISS KENNEDY (R4)
WILLIAM DEAN (NRR)
PETE ESELGROTH (R1)
JAY HENSON (R2)
SONIA BURGESS (R3)
KRISS KENNEDY (R4)
WILLIAM DEAN (NRR)
PART 21.21 REPORT INVOLVING STABILITY OPTION III
"Subject: Stability Option III: Possible Successive Confirmation Count Resets
"This letter provides notification of a 60 Day Interim Report per § 21.21 (a)(2) for plants that have selected stability long-term solution Option III. The basis for this notification is that GE Nuclear Energy (GE) has not completed the evaluation of a potential problem with the algorithm that provides the licensing basis Minimum Critical Power Ratio (MCPR) Safety Limit protection for stability Option III. The algorithm determines Successive Confirmation Count (SCC) of an oscillating power signal. A reactor trip is generated when SCC and oscillation amplitude reach their trip setpoints in accordance with the Option III and reactor protection system configuration. The concern is that the oscillation period could change for an oscillation that initiates while reactor state conditions are changing rapidly (e.g., during a two-recirculation pump trip event) and cause the SCC to reset, thus delaying the reactor scram.
"GE believes that there is low potential for the MCPR Safety Limit to be violated as a result of this concern. However, a 60 Day Interim Report is required since the evaluation has not been completed. Further information is provided in the attached notification.
"(ii) Identification of the facility, the activity, or the basic component supplied for such facility or such activity within the United States which fails to comply or contains a defect:
"The affected basic component is the Period Based Detection Algorithm (PBDA) of stability long-term solution Option III. The PEDA provides the licensing basis MCPR Safety Limit protection for anticipated coupled thermal hydraulic-neutronic reactor instabilities. The concern is that the Successive Confirmation Count (SCC) could reset if an oscillation develops while reactor state conditions are changing rapidly (e.g., during a two recirculation pump trip event) and delay a reactor scram beyond that assumed in the licensing basis analysis. The algorithm is more susceptible to SCC resets with a period tolerance that is near to the minimum allowed by licensing documents (e.g., 50 msec). SCC resets are less likely with higher period tolerance values (e.g., 100 to 300 msec).
"(iii) Identification of the firm constructing the facility or supplying the basic component which fails to comply or contains a defect:
"GE Nuclear Energy, San Jose, California
"(iv) Nature of the defect or failure to comply and safety hazard which is created or could be created by such defect or failure to comply:
"A reactor scram is only initiated by the PBDA when the SCC exceeds the count setpoint and the oscillation amplitude exceeds the amplitude setpoint The licensing basis is that the SCC will exceed the count setpoint before the amplitude reaches the amplitude setpoint. If the SCC resets, then the amplitude could exceed the amplitude setpoint before SCC reaches the count setpoint. This could lead to violation of the MCPR Safety Limit.
"If scram is delayed, boiling transition could be experienced on a portion of some fuel bundles. This would be a violation of a Technical Specification Safety Limit and is reportable under 10 CFR 21. However, it would not produce a significant safety hazard or threat to public health and safety.
"(v) The date on which the information of such defect or failure to comply was obtained:
"(vi) In the case of a basic component which contains a defect or failure to comply, the number and locations of all such components in use at, supplied for, or being supplied for one or more facilities or activities subject to the regulations in this part:
"A defect has not been confirmed to exist. The potentially affected plants are listed in Attachment 2.
"(vii) The corrective action which has been, is being, or will be taken; the name of the individual or organization responsible for the action; and the length of time that has been or will be taken to complete the action (note, these are actions specifically associated with the identified Reportable Condition):
"GE has communicated this concern to the BWR Owners' Group Potential Issues Resolution Team (PIRT) and to the Stability Detect & Suppress Committee.
"GE is continuing to evaluate the potential for the SCC to be reset for current licensed reactor operating conditions. This effort will be completed by November 18, 2002.
"(viii) Any advice related to the defect or failure to comply about the facility, activity, or basic component that has been, is being, or will be given to purchasers or licensees:
"It is recommended that potentially affected licensees keep informed through the BWR Owners' Group. No specific plant actions are recommended at this time."
Plants listed on Attachment 2
Clinton, Brunswick 1& 2, Nine Mile Point 2, Fermi 2, Columbia, Dresden 2 & 3, LaSalle 1 & 2, Limerick 1 & 2, Peach Bottom 2 & 3, Quad Cities 1 & 2, Perry 1, Susquehanna 1 & 2, Hope Creek, Hatch 1 & 2, and Browns Ferry 1, 2 & 3.
* * * UPDATE ON 11/18/02 AT 1856 FROM JASON POST (VIA FAX) TO GERRY WAIG * * *
"Subject: Final Report, Stability Option III: Possible Successive Confirmation Count Resets - Not Reportable
"Reference: MFN02-063, Stability Option III: Possible Successive Confirmation Count Resets, 10CFR Part 21 60 Day Interim Report, October 1, 2002
"This letter provides closure of the reference §21.21(a)(2) 60 Day Interim Report notification for plants that have selected stability long-term solution Option III. The closure is that GE Nuclear Energy (GE) has determined that this is not a reportable condition, however, GE recommends that the BWR Owners' Group Detect & Suppress Committee evaluate the need to change the minimum allowable value for period tolerance used in the Oscillation Power Range Monitor (OPRM).
"As described in the reference notification, the potential problem was associated with the algorithm that provides the licensing basis Minimum Critical Power Ratio (MCPR) Safety Limit protection for stability Option III. The algorithm determines Successive Confirmation Count (SCC) of an oscillating power signal. A reactor trip is generated when SCC and oscillation amplitude reach their trip setpoints in accordance with the Option III and reactor protection system configuration. The concern was that the oscillation period could change for an oscillation that initiates while reactor state conditions are changing towards equilibrium state (e.g., following a two-recirculation pump (2RPT) trip event) and cause the SCC to prematurely reset, thus delaying the reactor scram.
"A reactor trip signal is generated when the OPRM SCC setpoint and the amplitude setpoint are reached or exceeded for at least one OPRM cell in each trip system channel required to generate the trip signal (e.g., one-out-of two taken twice). The Period Based Detection Algorithm (PBDA) determines the SCC for each OPRM cell. When an oscillation in an OPRM cell signal is detected by the PBDA it sets the base period for that cell. The period tolerance is used to determine if the period of each subsequent oscillation is within an acceptable difference from the base period. The acceptable range for period tolerance specified in stability Option Ill licensing topical reports is 100 to 300 msec. A period tolerance of 50 msec has been approved for OPRM systems that have a 25 msec sampling frequency.
"GE evaluated this concern with TRACG simulations of a 2RPT event for typical Option III plants for reasonably limiting Extended Power Uprate (EPU) and Maximum Extended Load Line Limit Analysis (MELLLA) conditions. TRACG calculates channel power, which can be evaluated as representative of an OPRM cell signal through the hot channel oscillation reload licensing methodology, and evaluated by the PBDA for successive confirmation counts.
"PBDA resets occur when the difference between the current period and the base period exceeds the period tolerance. The worst case would be if a spurious SCC reset occurred immediately before the amplitude trip setpoint was reached. For this case, that cell would not generate a trip signal until SCC had again counted up to the trip setpoint, which could be a delay of 10 to 12 seconds.
"GE evaluated the potential for SCC spurious resets far period tolerance values of 50, 100 and 150 msec. In general, more frequent spurious resets occur with shorter period tolerance. However, the spurious SCC reset does not occur at the same time for all the OPRM cells in an OPRM channel. Some OPRM cell resets delay the trip generated by that cell, while others reset at sufficiently early times that they have again counted up to exceed the count setpoint when the amplitude setpoint is reached, and others do not reset at all. Only one OPRM cell trip in an OPRM channel is sufficient to cause an OPRM channel trip, and each OPRM channel typically has 18 to 33 OPRM cells. In addition, typical core loading schemes ensure that multiple OPRM cells respond very near the peak oscillation magnitude. The analysis concluded that even though spurious resets occur, these resets are not expected to significantly delay reactor scram. Therefore, the currently licensed PBDA provides adequate protection against a MCPR Safety Limit violation for instabilities initiated during a fast transient such as a 2RPT event. Therefore, this does not represent a Reportable Condition under 10CFR21.21.
"Even tough this is not a reportable condition, the potential for some OPRM cells to prematurely reset SCC for an instability initiated during a 2RPT is not consistent with thc original design basis of the PBDA. The original design basis was that continuous confirmation counts would occur for fully coupled neutronic/thermal-hydraulic reactor instability. Since this may not occur for a 2RPT with period tolerance values of 50 and 100 msec, it is recommended that Option III plants evaluate the need to change the minimum allowable value for period tolerance."
Notified (via email) R1DO (Mohamed Shanbaky), R2DO (David Ayres), R3DO ( Brent Clayton), R4DO (Dale Powers), NRREO (Stu Richards), NRR (Jack Foster).
"Subject: Stability Option III: Possible Successive Confirmation Count Resets
"This letter provides notification of a 60 Day Interim Report per § 21.21 (a)(2) for plants that have selected stability long-term solution Option III. The basis for this notification is that GE Nuclear Energy (GE) has not completed the evaluation of a potential problem with the algorithm that provides the licensing basis Minimum Critical Power Ratio (MCPR) Safety Limit protection for stability Option III. The algorithm determines Successive Confirmation Count (SCC) of an oscillating power signal. A reactor trip is generated when SCC and oscillation amplitude reach their trip setpoints in accordance with the Option III and reactor protection system configuration. The concern is that the oscillation period could change for an oscillation that initiates while reactor state conditions are changing rapidly (e.g., during a two-recirculation pump trip event) and cause the SCC to reset, thus delaying the reactor scram.
"GE believes that there is low potential for the MCPR Safety Limit to be violated as a result of this concern. However, a 60 Day Interim Report is required since the evaluation has not been completed. Further information is provided in the attached notification.
"(ii) Identification of the facility, the activity, or the basic component supplied for such facility or such activity within the United States which fails to comply or contains a defect:
"The affected basic component is the Period Based Detection Algorithm (PBDA) of stability long-term solution Option III. The PEDA provides the licensing basis MCPR Safety Limit protection for anticipated coupled thermal hydraulic-neutronic reactor instabilities. The concern is that the Successive Confirmation Count (SCC) could reset if an oscillation develops while reactor state conditions are changing rapidly (e.g., during a two recirculation pump trip event) and delay a reactor scram beyond that assumed in the licensing basis analysis. The algorithm is more susceptible to SCC resets with a period tolerance that is near to the minimum allowed by licensing documents (e.g., 50 msec). SCC resets are less likely with higher period tolerance values (e.g., 100 to 300 msec).
"(iii) Identification of the firm constructing the facility or supplying the basic component which fails to comply or contains a defect:
"GE Nuclear Energy, San Jose, California
"(iv) Nature of the defect or failure to comply and safety hazard which is created or could be created by such defect or failure to comply:
"A reactor scram is only initiated by the PBDA when the SCC exceeds the count setpoint and the oscillation amplitude exceeds the amplitude setpoint The licensing basis is that the SCC will exceed the count setpoint before the amplitude reaches the amplitude setpoint. If the SCC resets, then the amplitude could exceed the amplitude setpoint before SCC reaches the count setpoint. This could lead to violation of the MCPR Safety Limit.
"If scram is delayed, boiling transition could be experienced on a portion of some fuel bundles. This would be a violation of a Technical Specification Safety Limit and is reportable under 10 CFR 21. However, it would not produce a significant safety hazard or threat to public health and safety.
"(v) The date on which the information of such defect or failure to comply was obtained:
"(vi) In the case of a basic component which contains a defect or failure to comply, the number and locations of all such components in use at, supplied for, or being supplied for one or more facilities or activities subject to the regulations in this part:
"A defect has not been confirmed to exist. The potentially affected plants are listed in Attachment 2.
"(vii) The corrective action which has been, is being, or will be taken; the name of the individual or organization responsible for the action; and the length of time that has been or will be taken to complete the action (note, these are actions specifically associated with the identified Reportable Condition):
"GE has communicated this concern to the BWR Owners' Group Potential Issues Resolution Team (PIRT) and to the Stability Detect & Suppress Committee.
"GE is continuing to evaluate the potential for the SCC to be reset for current licensed reactor operating conditions. This effort will be completed by November 18, 2002.
"(viii) Any advice related to the defect or failure to comply about the facility, activity, or basic component that has been, is being, or will be given to purchasers or licensees:
"It is recommended that potentially affected licensees keep informed through the BWR Owners' Group. No specific plant actions are recommended at this time."
Plants listed on Attachment 2
Clinton, Brunswick 1& 2, Nine Mile Point 2, Fermi 2, Columbia, Dresden 2 & 3, LaSalle 1 & 2, Limerick 1 & 2, Peach Bottom 2 & 3, Quad Cities 1 & 2, Perry 1, Susquehanna 1 & 2, Hope Creek, Hatch 1 & 2, and Browns Ferry 1, 2 & 3.
* * * UPDATE ON 11/18/02 AT 1856 FROM JASON POST (VIA FAX) TO GERRY WAIG * * *
"Subject: Final Report, Stability Option III: Possible Successive Confirmation Count Resets - Not Reportable
"Reference: MFN02-063, Stability Option III: Possible Successive Confirmation Count Resets, 10CFR Part 21 60 Day Interim Report, October 1, 2002
"This letter provides closure of the reference §21.21(a)(2) 60 Day Interim Report notification for plants that have selected stability long-term solution Option III. The closure is that GE Nuclear Energy (GE) has determined that this is not a reportable condition, however, GE recommends that the BWR Owners' Group Detect & Suppress Committee evaluate the need to change the minimum allowable value for period tolerance used in the Oscillation Power Range Monitor (OPRM).
"As described in the reference notification, the potential problem was associated with the algorithm that provides the licensing basis Minimum Critical Power Ratio (MCPR) Safety Limit protection for stability Option III. The algorithm determines Successive Confirmation Count (SCC) of an oscillating power signal. A reactor trip is generated when SCC and oscillation amplitude reach their trip setpoints in accordance with the Option III and reactor protection system configuration. The concern was that the oscillation period could change for an oscillation that initiates while reactor state conditions are changing towards equilibrium state (e.g., following a two-recirculation pump (2RPT) trip event) and cause the SCC to prematurely reset, thus delaying the reactor scram.
"A reactor trip signal is generated when the OPRM SCC setpoint and the amplitude setpoint are reached or exceeded for at least one OPRM cell in each trip system channel required to generate the trip signal (e.g., one-out-of two taken twice). The Period Based Detection Algorithm (PBDA) determines the SCC for each OPRM cell. When an oscillation in an OPRM cell signal is detected by the PBDA it sets the base period for that cell. The period tolerance is used to determine if the period of each subsequent oscillation is within an acceptable difference from the base period. The acceptable range for period tolerance specified in stability Option Ill licensing topical reports is 100 to 300 msec. A period tolerance of 50 msec has been approved for OPRM systems that have a 25 msec sampling frequency.
"GE evaluated this concern with TRACG simulations of a 2RPT event for typical Option III plants for reasonably limiting Extended Power Uprate (EPU) and Maximum Extended Load Line Limit Analysis (MELLLA) conditions. TRACG calculates channel power, which can be evaluated as representative of an OPRM cell signal through the hot channel oscillation reload licensing methodology, and evaluated by the PBDA for successive confirmation counts.
"PBDA resets occur when the difference between the current period and the base period exceeds the period tolerance. The worst case would be if a spurious SCC reset occurred immediately before the amplitude trip setpoint was reached. For this case, that cell would not generate a trip signal until SCC had again counted up to the trip setpoint, which could be a delay of 10 to 12 seconds.
"GE evaluated the potential for SCC spurious resets far period tolerance values of 50, 100 and 150 msec. In general, more frequent spurious resets occur with shorter period tolerance. However, the spurious SCC reset does not occur at the same time for all the OPRM cells in an OPRM channel. Some OPRM cell resets delay the trip generated by that cell, while others reset at sufficiently early times that they have again counted up to exceed the count setpoint when the amplitude setpoint is reached, and others do not reset at all. Only one OPRM cell trip in an OPRM channel is sufficient to cause an OPRM channel trip, and each OPRM channel typically has 18 to 33 OPRM cells. In addition, typical core loading schemes ensure that multiple OPRM cells respond very near the peak oscillation magnitude. The analysis concluded that even though spurious resets occur, these resets are not expected to significantly delay reactor scram. Therefore, the currently licensed PBDA provides adequate protection against a MCPR Safety Limit violation for instabilities initiated during a fast transient such as a 2RPT event. Therefore, this does not represent a Reportable Condition under 10CFR21.21.
"Even tough this is not a reportable condition, the potential for some OPRM cells to prematurely reset SCC for an instability initiated during a 2RPT is not consistent with thc original design basis of the PBDA. The original design basis was that continuous confirmation counts would occur for fully coupled neutronic/thermal-hydraulic reactor instability. Since this may not occur for a 2RPT with period tolerance values of 50 and 100 msec, it is recommended that Option III plants evaluate the need to change the minimum allowable value for period tolerance."
Notified (via email) R1DO (Mohamed Shanbaky), R2DO (David Ayres), R3DO ( Brent Clayton), R4DO (Dale Powers), NRREO (Stu Richards), NRR (Jack Foster).
General Information or Other
Event Number: 39244
Rep Org: CALIFORNIA RADIATION CONTROL PRGM
Licensee: JIM TAYLOR
Region: 4
City: STOCKTON State: CA
County:
License #: 4900
Agreement: Y
Docket:
NRC Notified By: R. GREGER
HQ OPS Officer: JOHN MacKINNON
Licensee: JIM TAYLOR
Region: 4
City: STOCKTON State: CA
County:
License #: 4900
Agreement: Y
Docket:
NRC Notified By: R. GREGER
HQ OPS Officer: JOHN MacKINNON
Notification Date: 10/03/2002
Notification Time: 09:35 [ET]
Event Date: 10/01/2002
Event Time: 09:30 [PDT]
Last Update Date: 10/03/2002
Notification Time: 09:35 [ET]
Event Date: 10/01/2002
Event Time: 09:30 [PDT]
Last Update Date: 10/03/2002
Emergency Class: NON EMERGENCY
10 CFR Section:
10 CFR Section:
Person (Organization):
KRISS KENNEDY (R4)
FRED BROWN (NMSS)
KRISS KENNEDY (R4)
FRED BROWN (NMSS)
MISSING CPN GAUGE
The Licensee had a CPN moisture density gauge in a box of his ATV he uses for transport in the agriculture fields. He stopped at a porta-potty on Duncan Road near Stockton, CA. When he came out of the porta potty the gauge was missing.
The gauge is a CPN Hydroprobe model No. 503DR. Serial No: H36107151. Gauge contains 10 millicuries of Cs-137 and 30 millicuries of Am-241.
The Licensee will inform the local police of the missing gauge and he will run an offer of a reward in a local newspaper for the recovery of the gauge.
The Licensee had a CPN moisture density gauge in a box of his ATV he uses for transport in the agriculture fields. He stopped at a porta-potty on Duncan Road near Stockton, CA. When he came out of the porta potty the gauge was missing.
The gauge is a CPN Hydroprobe model No. 503DR. Serial No: H36107151. Gauge contains 10 millicuries of Cs-137 and 30 millicuries of Am-241.
The Licensee will inform the local police of the missing gauge and he will run an offer of a reward in a local newspaper for the recovery of the gauge.