05000341/LER-2002-002
| Fermi 2 | |
| Event date: | 02-19-2002 |
|---|---|
| Report date: | 06-26-2002 |
| 3412002002R01 - NRC Website | |
Initial Plant Conditions:
Mode � 1 Reactor Power � 97 percent
Description of the Event
As a result of a fire protection program self assessment, on May 2, 2002, Detroit Edison Company (DECo) determined that a field modification performed on February 19, 2002 invalidated an inherent assumption in the procedure for controlling the plant from the dedicated shutdown panel. Specifically, the motor operator for motor operated valve (MOV) N2000F636, Condenser Hotwell Emergency Makeup Bypass Valve [SD][ISV], was rotated 180 degrees to help alleviate an oil leakage problem from the motor operator. Rotating the MOV relocated the motor operator handwheel away from the first floor of the Turbine Building such that operators could not reasonably close the valve without the use of a ladder. A dedicated ladder had not been staged for this purpose. The Central Component (CECO) database identified this valve as a balance-of-plant component and did not associate it with the fire protection program.
Procedure 20.000.18, "Control of the Plant from the Dedicated Shutdown Panel," directs operators to de- energize power to and manually close valve N2000F636 to prevent losing Condensate Storage Tank (CST) [ICA][TK] water inventory to the Hotwell [SG]. N2000F636 is normally closed; however, a hot short could potentially cause it to open. By rotating the handwheel away from the floor and not staging a dedicated ladder near the valve, operators would have had to obtain a ladder from another location for use in performing this procedural step. This would have required more time to complete the sequence of steps to isolate the CST from the Hotwell and, if delayed long enough, could have resulted in losing more water from the tank leaving less than the minimum amount required for reactor shutdown. Loss of water from the CST threatens the ability of the Standby Feedwater (SBFW) [SJ] system pumps to provide high pressure makeup water to the Reactor Pressure Vessel (RPV) [RPV] for the time period needed until shutdown cooling could be initiated. The dedicated shutdown system required by 10 CFR 50, Appendix R, Section 111.G.3, relies on the SBFW system to inject water from the CST into the RPV in the case of a fire in certain fire zones.
Detroit Edison concluded that the field modification performed on N2000F636 increased the time required to isolate the CST from the Hotwell and could have adversely affected the ability to achieve safe shutdown conditions in the event of a fire.
Section 2.C.(9)(a) of the Fermi 2 Operating License states: "DECo may make changes to the approved fire protection program without prior approval of the Commission only if those changes would not adversely affect the ability to achieve and maintain safe shutdown in the event of a fire.
Section 2.F of the Fermi 2 Operating License states: "Except as otherwise provided in the Technical Specifications or Environmental Protection Plan, DECo shall report any violations of the requirements contained in Section 2.0 of this license in the following manner: initial notification shall be made within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to the NRC Operations Center via the Emergency Notification System with written followup within thirty days in accordance with the procedures described in 10 CFR 50.73(b), (c) and (e).
Cause of the Event
The cause of this event was the failure to properly identify the association of MOV N2000F636 with the fire protection program in the plant CECO database and failure of the work control process to identify the impact of rotating the motor operator on the dedicated shutdown scenario.
Analysis of the Event
Valve N2000F636 is an eight-inch motor operated valve in the condensate transfer piping. The open valve provides a direct pathway from the CST through the emergency hotwell pump to the condenser hotwell.
In the event a fire causes sufficient damage to require entry into Abnormal Operating Procedure (AOP) 20.000.18, certain plant equipment is transferred over to local control and is locally operated to recover reactor coolant inventory and maintain hot shutdown, establish torus and drywell cooling, and initiate the shutdown cooling mode of the Residual Heat Removal (RHR) [BO] system within ten hours. If a loss of offsite power occurs, the Combustion Turbine Generator (CTG) 11-1 is started from the local Dedicated Shutdown Panel and the breakers are lined up to power the SBFW pumps. The CST provides the water inventory for operation of the SBFW system in the Dedicated Shutdown scenario.
In the unlikely event of an Appendix R fire which induced a hot short and repositioned the closed N2000F636 valve such that the CST had an open path to the Hotwell, it is anticipated that the operators would take action to obtain one of the Appendix R dedicated ladders staged along the lighted path to the valve and close the valve. Time analysis of the steps in procedure 20.000.18 indicates that the operators would have likely closed the valve in time, since they would have had over 10 additional minutes before CST water inventory is reduced below the minimum amount required for reactor shutdown. Therefore, this event is determined to be of minor safety significance. Additionally, the Dedicated Shutdown Panel provides the appropriate indications to apprise the operators of the CST level. During the time that CST water is required to achieve shutdown, before shutdown cooling has been initiated, the operators would have recognized the need for adding water to the CST and would have taken actions to make up the amount of water needed to remotely shutdown and cooldown the reactor. Potential makeup water sources include water from the Condensate Return Tank (CRT) or the Hotwell; however, actions for obtaining a ladder or adding water to the CST are not described in procedure 20.000.18.
Based on the above discussion, the health and safety of the public were not adversely affected by this condition.
Corrective Actions
Upon discovery of this event, a dedicated ladder was staged at the valve to provide access for manually closing the valve as directed by procedure 20.000.18. All other components requiring operator action in procedure 20.000.18 were verified to be accessible and an analysis of operator actions in the procedure validated the capability of manually achieving and maintaining safe shutdown conditions from outside the control room.
This event has been documented in the Fermi 2 corrective action program (CARD 02-12412). The corrective actions will be tracked and implemented commensurate with the established processes and priorities of the program. Corrective actions include the following:
1. The identification of Appendix R structures, systems and components in the CECO database.
2. The creation of a periodic verification process for a step-by-step validation of procedure 20.000.18 to ensure operators can perform the specific actions as described in the procedure.
3. Providing guidance in Work Control procedures on the preparation of work packages involving Appendix R structures, systems and components.
4. Providing training to plant operators regarding the basis for manual actions associated with Appendix R fire scenario.
All corrective actions will be completed by November 30, 2002 except for operator training which will be completed by March 31, 2003.
Additional Information
A. Failed Components: None B. Previous LERs on Similar Problems On October 27, 1999, it was determined that a deficiency existed in the dedicated shutdown procedure used for plant shutdown in the event of fires in certain areas of the plant. The dedicated shutdown procedure did not include a required action for fires in all fire zones for which the action would be required. The dedicated shutdown procedure requires isolation of the control air supply for the High Pressure Coolant Injection (HPCI) system test return line control valve, E41F011, only for some fires in some of the fire zones where the action is required. Isolation of the control air supply is required to prevent fire induced spurious opening of the HPCI test return line control valve which, in combination with fire induced spurious opening of two other valves, could result in Standby Feedwater (SBFW) flow being bypassed to the Condensate Storage Tank (CST), reducing flow to the reactor vessel. The cause of this event was not having adequate involvement of a fire protection engineer in the development and review of procedure changes.
On March 18, 1998, it was determined that fire induced multiple hot shorts could cause spurious valve operations which could reopen closed valves and result in Condensate Storage Tank (CST) inventory to drain to Condenser Hotwell. This could have resulted in a loss of CST inventory necessary for safe shutdown following a fire. Procedures were revised to de-energize appropriate valves to prevent this drain path. The cause of this event was inadequate cross-discipline review of assumptions made in the fire protection program safe shutdown evaluation.
On November 15, 1996, a Deviation Event Report (DER) was initiated to investigate the adequacy of the water supply for the Standby Feedwater (SBFW) system to meet Appendix R requirements. The water supply for SBFW is from a nine foot standpipe in the Condensate Storage Tank (CST). Technical Specification (TS) 3.7.11 required an operable SBFW system consisting of two operable SBFW pumps and an operable flow path from the CST to the reactor vessel. The cause of this event was an inadequate design review of the Appendix R Dedicated Shutdown Method during design development in 1984.
Appropriate operating procedures were revised to maintain the required volume of water in the CST at greater than 22 feet.