05000244/LER-2006-005

LER-2006-005, B Containment Sump Covered While in Mode 4

Docket Number Sequential Revmonth Day Year Year Month Day Yearnumber No. 05000
Event date:	10-09-2006
Report date:	12-06-2006
Initial Reporting
ENS 42892	10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
2442006005R00 - NRC Website

I.�PRE-EVENT PLANT CONDITIONS:

On October 9, 2006 Ginna was in the process of cooling down for the 2006 refueling and extended power uprate outage. The plant had entered Mode 4 at 0105 and was continuing the cooldown to Mode 5.

H.�DESCRIPTION OF EVENT:

A. EVENT:

Early on October 9, 2006 a series of events led to installation of temporary shielding over the Emergency Core Cooling System (ECCS) B Containment Sump while the plant was in Mode 4. This sump provides the suction source for the ECCS pumps in the recirculation mode. The shielding consisted of lead blankets which covered a large portion of the grating over the sump inlet. While in Mode 4, the B Containment Sump must remain available as a suction source in the event the recirculation mode of ECCS injection is necessary. Covering the sump grating resulted in a violation of Ginna Technical Specification (TS) 3.5.3. The shielding was directed to be removed when the condition was realized.

CONTRIBUTED TO THE EVENT:

None

C. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES:

October 9, 2006, 0105 EDST: Plant leaves Mode 3 and enters Mode 4 October 9, 2006, 0230 EDST: Shielding installed over B Containment Sump.

October 9, 2006, 0400 EDST: B Containment Sump declared inoperable.

October 9, 2006, 0815 EDST: Plant enters Mode 5. Exited the TS action statement for B Containment Sump inoperability.

October 9, 2006, 1052 EDST: Notification made to NRC per 10CFR50.72(b)(3)(v)(D), event number 42892.

D. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:

None, since there were no failures of any components with multiple functions.

E. METHOD OF DISCOVERY:

An Engineer attempting to enter B Containment Sump was turned away by Operations because the sump was "protected." The Radiation Protection (RP) Outage Manager then questioned why the sump was being shielded if it was "protected." An investigation then indicated that the sump had been made inoperable by the shieldineduring the existing plant Mode (4).

F. SAFETY SYSTEM RESPONSES:

There were no safety system responses required.

III. CAUSE OF EVENT:

The events are NUREG-1022 Cause Code (a), "Personnel Error" and (d), Defective Procedures.

A formal Root Cause Evaluation has been initiated. The evaluation identified the following root causes:

• Configuration management practices, including the development and administration of the Minimal Essential Equipment List (MEEL), did not meet industry standards.

• Weaknesses in the schedule development process led to missing or incorrect logic ties to the appropriate plant conditions and Modes.

IV. ASSESSMENT OF THE SAFETY CONSEQUENCES OF THE EVENT:

This event is reportable in accordance with 10 CFR 50.73, Licensee Event Report System, item (a)(2)(i)(B), which requires a report of, "Any operation or condition which was prohibited by the plant's Technical Specifications," and (a)(2)(v)(D) which requires a report of, "Any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident.

The Ginna UFSAR Section 6.3.3.11 states in part: "There are no applicable safety analyses which apply to the emergency core cooling system (ECCS) when in MODE 4 (Hot Standby) due to the stable conditions associated with operation in MODE 4 and the reduced probability of occurrence of a design-basis accident. The MODE 4 loss-of-coolant accident (LOCA) evaluation is bounded by the performance of the ECCS while in MODES 1-3, and Technical Specifications require only a single train of ECCS while in MODE 4." Because the sump is common to both ECCS trains, neither train could be considered operable. To assess the safety consequences of the event, the following must be considered:

• The ability of the ECCS to inject into the core was not affected by this event.

• The flow requirements for event mitigation would be reduced in Mode 4 because of the reduced energy in the system.

• Ginna Procedure AP-RCS.4, Shutdown LOCA, guides the operators to initiate only the required injection flow based on plant parameters (sub-cooling, pressurizer level, etc), reducing the likelihood that sump recirculation would be required.

• There was approximately 300,000 gallons of borated water available in the Refueling Water Storage Tank (RWST) for injection at the time. The sump function is not required until recirculation is started, and recirculation would not be started until the injection source was depleted.

• At the time of this event, the RCS was at significantly reduced pressure (below 350 psig) and temperature (below 350 deg F) such that the potential for a break in the RCS was significantly reduced.

• At the time of this event, only a single RCP was running, and the RCS was at reduced pressure and temperature, such that the potential for an RCP seal LOCA, given a loss of all seal cooling, was also greatly reduced.

• For smaller pipe break LOCAs and RCP seal LOCAs, it is highly likely that the RCS could be cooled down below 212 deg F and depressurized to atmospheric pressure long before the RWST was emptied. Procedure AP-RCS.4, Shutdown LOCA, directs a cooldown to less than 200 deg at 100 deg per hour. Starting at 350 deg, this would take less than 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. Once in this condition, with normal RHR cooling, the plant would be in a stable condition and no sump recirculation would be required, unless the LOCA was a break in the RCS below mid-loop level. Even if the break was below mid-loop, it is likely that there would be a significant amount of water left in the RWST when atmospheric pressure is reached in the RCS. At this point, break flow would be by gravity only and would be very low, allowing significant time for recovery actions if sump recirculation was unavailable.

• Because of the reduced injection flow, additional time would be available to provide alternate makeup sources of injection water if necessary, such as blending to the RWST and/or transferring borated water from other sources, if adequate recirculation could not be obtained. Also, the core was at end of life conditions and the shutdown margin requirements were proportionally reduced, thus allowing the option of utilizing injection sources of lesser boron concentration if needed.

• Although the precise extent of the shielding covering the sump inlet grating is not documented, it is known that the entire area of the sump grating was not covered for the entire time that the B Containment Sump was considered inoperable, and some flow into the sump would have been expected.

Based on the above considerations, the safety consequences of this event are very low.

V.�CORRECTIVE ACTIONS:

A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT

NORMAL STATUS:

The shielding was removed from the sump.

B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

Initial action taken:

1. A Prompt Investigation was initiated.

2. A risk assessment of the work schedule was performed.

3. A team from Operations was assigned to perform a daily risk assessment of the outage schedule.

Because of similar previous events (see VI.B below) and a subsequent TS violation which occurred within days of this event (see LER 2006-006), a formal Root Cause Evaluation was initiated. The following actions are planned as a result of that evaluation:

1. Implement and basis capture NUMARC 91-06, Guidelines for Industry Actions to Assess Shutdown Management, including:

a) Develop a MEEL and implement effective oversight processes for support, including contingency planning for periods when the minimum equipment requirements may be challenged.

b) Improve the timeliness of the Shutdown Safety Summary Schedule (S4) development.

c) Implement a Conduct of Lower Mode Operations procedure.

2. Revise IP-OUT-1, Outage Scheduling, to include guidance on schedule development and review.

a) Include senior licensed personnel involvement in schedule development b) Specify minimum quorum requirements that ensure heavy participation from senior licensed level individuals in the schedule review process (vertical and horizontal) c) Specify how impacts to a reviewed schedule, including integrity of logic ties, will be incorporated and reviewed.

A. FAILED COMPONENTS:

There were no failed components associated with this event.

B. PREVIOUS LERs ON SIMILAR EVENTS:

Note: Although not reportable under 10CFR50.73, a related event occurred during the 2003 refueling outage. The B Containment Sump was partially covered with a tarp while in Mode 6, contrary to Ginna's administrative requirements.

C. THE ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) COMPONENT

SYSTEM REFERRED TO IN THIS LER:

COMPONENT�IEEE 803 � IEEE 805

FUNCTION IDENTIFIER SYSTEM IDENTIFICATION

�Sump SUMP� BP

D. SPECIAL COMMENTS:

None