| U.S. Nuclear Regulatory Commission
Operations Center Event Reports For
01/08/2008 - 01/09/2008 ** EVENT NUMBERS ** |
 | Power Reactor | Event Number: 43885 | Facility: PILGRIM
Region: 1 State: MA
Unit: [1] [ ] [ ]
RX Type: [1] GE-3
NRC Notified By: FRANK CLIFFORD
HQ OPS Officer: STEVE SANDIN | Notification Date: 01/08/2008
Notification Time: 16:47 [ET]
Event Date: 01/08/2008
Event Time: 10:40 [EST]
Last Update Date: 01/08/2008 | Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
| Person (Organization):
ANTHONY DIMITRIADIS (R1)
|
| Unit | SCRAM Code | RX CRIT | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode | | 1 | N | Y | 100 | Power Operation | 100 | Power Operation | Event Text RCIC INOPERABLE DUE TO MIN FLOW VALVE INABILITY TO REPOSITION
"This report is being made in accordance with 10 CFR 50.72 (b) (3) (v) due to the Reactor Core Injection Cooling (RCIC) system being determined to be inoperable on 01/08/08 at 1040 EST. During a planned RCIC system outage, an instrument calibration surveillance identified a flow switch failure that would have prevented automatic closure of the pump minimum flow valve. Insufficient data is immediately available to assess the ability to achieve design basis flow rates with the minimum flow valve open. This event is an eight-hour notification. The RCIC instrument is currently under repair and will be completed prior to return to service.
"Plant is in a stable condition. Investigation is continuing.
"The resident NRC inspector has been notified of this event."
This event places them in a 14-day LCO per ACT-1-08-002. HPCI verified operable. |
| Power Reactor | Event Number: 43886 | Facility: FT CALHOUN
Region: 4 State: NE
Unit: [1] [ ] [ ]
RX Type: [1] CE
NRC Notified By: SCOTT LINDQUIST
HQ OPS Officer: JEFF ROTTON | Notification Date: 01/08/2008
Notification Time: 20:33 [ET]
Event Date: 01/08/2008
Event Time: 11:42 [CST]
Last Update Date: 01/08/2008 | Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(v)(B) - POT RHR INOP
| Person (Organization):
RUSSELL BYWATER (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 | Event Text POTENTIAL LOCA INJECTION FLOW RATE ISSUE
"At 11:42 CST, a condition report was initiated that questioned the specified flow path for simultaneous hot and cold leg injection following a large break loss of coolant accident (LOCA). When an unisolated LOCA event exists, simultaneous hot leg and cold leg injection should be implemented if the plant cannot be placed on shutdown cooling within six hours of the LOCA initiation and RCS pressure is less than 120 psia. The procedure is implemented at five and one-half hours to provide adequate time to align simultaneous hot/cold leg injection before the six hour time limit. Injecting to each side of the reactor vessel at an injection rate greater than 165 gpm, ensures that fluid from the reactor vessel (where the boric acid is being concentrated) flows out of the break regardless of the break location and is replenished with a dilute solution of borated water from the other side of the reactor vessel. The action is taken between 5.5 and 6 hours after the LOCA in order to ensure that the buildup of boric acid is terminated well before the potential for boric acid precipitation occurs which could restrict coolant flow through the core. Once the RCS is refilled, the boric acid is dispersed throughout the RCS via natural circulation. If entry into shutdown cooling system operation is anticipated before the 5.5 hour limit, then the realignment to hot/cold leg injection is unnecessary.
"The potential concern is associated with a charging line thermal relief valve CH-202 bypassing flow from hot leg injection and preventing the required flow rate needed to prevent boron precipitation from occurring. A minimum injection rate of 147 gpm to the cold legs and 159 gpm to the hot legs is required to prevent boric acid precipitation. Total hot leg injection flow is measured at FIA-236. Cold leg injection flow is the total of the four HPSI flow instruments, FI-313, FI-316, FI-319, and FI-322 with 50 gpm the minimum flow indication. A total cold leg injection flow of at least 200 gpm ensures at least 150 pm flow into the core, assuming 25% spillage out the break. This meets the required minimum of 147 gpm. It could not be determined through a review of the design basis documents and associated calculations what, if any, bypass flow is assumed through CH-202.
"Current procedural guidance in the emergency operating procedures is to align a high pressure safety injection pump to the charging header and provide hot leg injection from auxiliary pressurizer spray valves attached to the charging headers through the pressurizer and into the hot leg. The current procedural guidance does not isolate CH-202 and due to the location of flow instrument FIA-236, it cannot be guaranteed that all the flow through the charging system is being injected into the hot leg or being diverted through the normal charging line. As a result the potential existed which could have prevented the fulfillment of the safety function of a system needed to remove residual heat. Therefore this report is being made in reference to 10 CFR 50.72 (b) (3) (v) (B).
"Efforts are continuing to review design basis documents and calculations to determine if bypass flow was assumed past CH-202 when determining the minimum hot leg injection rate. As a compensatory measure, Operations management has restricted the use of hot and cold leg injection via the charging header until the design basis review confirms the adequacy of the current procedural guidance or the procedural guidance is revised. Pre-approved alternative methods will be utilized via the emergency operating procedures to perform simultaneous hot and cold leg injection if required."
No LCO condition exists. The licensee notified the NRC Resident Inspector. | |