Event Notification Report for May 21, 2015
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
05/20/2015 - 05/21/2015
Power Reactor
Event Number: 51083
Facility: RIVER BEND
Region: 4 State: LA
Unit: [1] [] []
RX Type: [1] GE-6
NRC Notified By: JACK McCOY
HQ OPS Officer: HOWIE CROUCH
Region: 4 State: LA
Unit: [1] [] []
RX Type: [1] GE-6
NRC Notified By: JACK McCOY
HQ OPS Officer: HOWIE CROUCH
Notification Date: 05/21/2015
Notification Time: 12:03 [ET]
Event Date: 05/21/2015
Event Time: 03:09 [CDT]
Last Update Date: 05/21/2015
Notification Time: 12:03 [ET]
Event Date: 05/21/2015
Event Time: 03:09 [CDT]
Last Update Date: 05/21/2015
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(v)(A) - POT UNABLE TO SAFE SD
10 CFR Section:
50.72(b)(3)(v)(A) - POT UNABLE TO SAFE SD
Person (Organization):
NICK TAYLOR (R4DO)
NICK TAYLOR (R4DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
DC ELECTRICAL ROOM HEAT LOAD CALCULATIONS NOT UPDATED AFTER NEW INVERTERS INSTALLED
"At 0309 CDT on May 21, 2015, with the plant operating at 100 percent power, the shift manager was notified of a condition that could potentially lead to the failure of safety-related inverters in the DC electrical distribution system. This condition was identified while reviewing completed probabilistic risk analysis (PRA) calculations. It was discovered that control building ventilation system heat load calculations were not updated when new AC/DC inverters, with significantly higher heat output, were installed in 2007. Since the heat load calculations were not updated, it was not realized at the time that, under post-accident conditions involving a specific single failure, the DC electrical equipment rooms (i.e., inverters and battery chargers) could exceed their design basis ambient temperature, potentially leading to the failure of the inverters or battery chargers, and the loss of DC power in both divisions of the distribution system. The postulated scenario is the loss of offsite power (LOP)/loss of coolant accident (LOCA), followed by the failure of a single emergency diesel generator. If within 20 minutes prior to the onset of the event, the control building ventilation system had been shifted to the division in which the emergency diesel generator successfully started, the chiller in that division would, by design, be prevented from re-starting for as much as 20 minutes by its anti-recycle feature. (That feature limits successive starts of a chiller to prevent over-heating the motor.) The other chiller in that same division must be manually aligned for service, so it is not assumed to be available for these purposes. During the period in which the anti-recycle timer is running, no chiller would be in service, and the actual heatup rate of the inverters/battery charger could lead to room temperatures in excess of their design basis assumptions. As stated above, this condition (no ventilation cooling) would only exist for a maximum of 20 minutes from the time the associated divisional chiller was started, concurrent with a LOP/LOCA and a single failure. After expiration of the 20 minute timer, the chiller would perform the required function and lower room temperatures as expected. For best estimate PRA purposes, River Bend assumes an equipment survivability criteria of exposure to temperatures above 122 degrees F, but below 150 degrees F, for up to four hours. This is based upon the industry Station Blackout guidance of NUMARC 87-00, which was endorsed by the NRC as the basis for industry response to the Station Blackout Rule. This condition exists only after planned chiller swap and can be mitigated by opening the door to the inverter room should a LOP/ LOCA occur prior to the expiration of the 20 minute timer. Measures are in place for a dedicated operator to perform this function pending a modification to resolve the issue.
"This condition is being reported in accordance with 10 CFR 50.72(b)(3)(v) as the potential loss of the safety function of the DC electrical distribution system."
The licensee has notified the NRC Resident Inspector.
"At 0309 CDT on May 21, 2015, with the plant operating at 100 percent power, the shift manager was notified of a condition that could potentially lead to the failure of safety-related inverters in the DC electrical distribution system. This condition was identified while reviewing completed probabilistic risk analysis (PRA) calculations. It was discovered that control building ventilation system heat load calculations were not updated when new AC/DC inverters, with significantly higher heat output, were installed in 2007. Since the heat load calculations were not updated, it was not realized at the time that, under post-accident conditions involving a specific single failure, the DC electrical equipment rooms (i.e., inverters and battery chargers) could exceed their design basis ambient temperature, potentially leading to the failure of the inverters or battery chargers, and the loss of DC power in both divisions of the distribution system. The postulated scenario is the loss of offsite power (LOP)/loss of coolant accident (LOCA), followed by the failure of a single emergency diesel generator. If within 20 minutes prior to the onset of the event, the control building ventilation system had been shifted to the division in which the emergency diesel generator successfully started, the chiller in that division would, by design, be prevented from re-starting for as much as 20 minutes by its anti-recycle feature. (That feature limits successive starts of a chiller to prevent over-heating the motor.) The other chiller in that same division must be manually aligned for service, so it is not assumed to be available for these purposes. During the period in which the anti-recycle timer is running, no chiller would be in service, and the actual heatup rate of the inverters/battery charger could lead to room temperatures in excess of their design basis assumptions. As stated above, this condition (no ventilation cooling) would only exist for a maximum of 20 minutes from the time the associated divisional chiller was started, concurrent with a LOP/LOCA and a single failure. After expiration of the 20 minute timer, the chiller would perform the required function and lower room temperatures as expected. For best estimate PRA purposes, River Bend assumes an equipment survivability criteria of exposure to temperatures above 122 degrees F, but below 150 degrees F, for up to four hours. This is based upon the industry Station Blackout guidance of NUMARC 87-00, which was endorsed by the NRC as the basis for industry response to the Station Blackout Rule. This condition exists only after planned chiller swap and can be mitigated by opening the door to the inverter room should a LOP/ LOCA occur prior to the expiration of the 20 minute timer. Measures are in place for a dedicated operator to perform this function pending a modification to resolve the issue.
"This condition is being reported in accordance with 10 CFR 50.72(b)(3)(v) as the potential loss of the safety function of the DC electrical distribution system."
The licensee has notified the NRC Resident Inspector.
Agreement State
Event Number: 51090
Rep Org: ILLINOIS EMERGENCY MGMT. AGENCY
Licensee: PIONEER ENVIRONMENTAL SERVICES, LLC
Region: 3
City: CHICAGO State: IL
County:
License #: IL-02451-01
Agreement: Y
Docket:
NRC Notified By: DARREN PERRERO
HQ OPS Officer: JEFF HERRERA
Licensee: PIONEER ENVIRONMENTAL SERVICES, LLC
Region: 3
City: CHICAGO State: IL
County:
License #: IL-02451-01
Agreement: Y
Docket:
NRC Notified By: DARREN PERRERO
HQ OPS Officer: JEFF HERRERA
Notification Date: 05/26/2015
Notification Time: 16:04 [ET]
Event Date: 05/21/2015
Event Time: 16:00 [CDT]
Last Update Date: 05/26/2015
Notification Time: 16:04 [ET]
Event Date: 05/21/2015
Event Time: 16:00 [CDT]
Last Update Date: 05/26/2015
Emergency Class: NON EMERGENCY
10 CFR Section:
10 CFR Section:
Person (Organization):
CHRISTINE LIPA (R3DO)
NMSS_EVENTS_NOTIFIC (EMAI)
CHRISTINE LIPA (R3DO)
NMSS_EVENTS_NOTIFIC (EMAI)
AGREEMENT STATE REPORT - NUCLEAR DENSITY GAUGE DAMAGED AT CONSTRUCTION SITE
The following report was received from the Illinois Emergency Management Agency via email:
"On the afternoon of May 21, the Agency [Illinois Emergency Management Agency] received a call from the licensee's radiation safety officer (RSO) who explained that their portable moisture density gauge had been involved in an accident at a construction site in Barrington, IL. The gauge operator had been briefly called away from the device and during his absence, the device was struck by a piece of heavy machinery. The RSO indicated that the operator had gathered up the pieces and put them into the transportation case and was in the process of returning the broken device to the company's Chicago storage facility at the time of the RSO's notification. Pictures provided by the RSO showed that the rod which contained the Cs-137 was significantly bent some 4 inches from its end and was no longer in its shielded position. The operator secured the device in a remote location upon his return to the storage facility that night until Agency inspectors could be dispatched to the location.
"The next morning, inspectors arrived at the storage location and conducted surveys including field leak tests of the sources. Those tests showed no leakage of radioactive material but determined that elevated radiation levels of up to 60 [millirem/h] were present at the surface of the transportation case. After providing additional storage suggestions, the pieces of the gauge were reconfigured and secured at the site. Dose rates were lowered to 16 [millirem/h] near the surface of the case and less than 1 [millirem/h] at 1 foot by those efforts.
"The gauge manufacturer was contacted and asked to provide a shipping container and additional shielding for return of the damaged device. When those materials are received, Agency inspectors will return to the site and verify the gauge is properly packaged and documented for return. This item remains open at this time pending this additional action and receipt of the licensee's written report which is due in 30 days.
"Device manufacturer: Troxler
Model Number: 3430
Serial Number: 68332
Device activity content: 0.008 Ci - Cs-137, 0.040 Ci - Am/Be
"Illinois Event Number: IL15011"
The following report was received from the Illinois Emergency Management Agency via email:
"On the afternoon of May 21, the Agency [Illinois Emergency Management Agency] received a call from the licensee's radiation safety officer (RSO) who explained that their portable moisture density gauge had been involved in an accident at a construction site in Barrington, IL. The gauge operator had been briefly called away from the device and during his absence, the device was struck by a piece of heavy machinery. The RSO indicated that the operator had gathered up the pieces and put them into the transportation case and was in the process of returning the broken device to the company's Chicago storage facility at the time of the RSO's notification. Pictures provided by the RSO showed that the rod which contained the Cs-137 was significantly bent some 4 inches from its end and was no longer in its shielded position. The operator secured the device in a remote location upon his return to the storage facility that night until Agency inspectors could be dispatched to the location.
"The next morning, inspectors arrived at the storage location and conducted surveys including field leak tests of the sources. Those tests showed no leakage of radioactive material but determined that elevated radiation levels of up to 60 [millirem/h] were present at the surface of the transportation case. After providing additional storage suggestions, the pieces of the gauge were reconfigured and secured at the site. Dose rates were lowered to 16 [millirem/h] near the surface of the case and less than 1 [millirem/h] at 1 foot by those efforts.
"The gauge manufacturer was contacted and asked to provide a shipping container and additional shielding for return of the damaged device. When those materials are received, Agency inspectors will return to the site and verify the gauge is properly packaged and documented for return. This item remains open at this time pending this additional action and receipt of the licensee's written report which is due in 30 days.
"Device manufacturer: Troxler
Model Number: 3430
Serial Number: 68332
Device activity content: 0.008 Ci - Cs-137, 0.040 Ci - Am/Be
"Illinois Event Number: IL15011"