05000305/LER-2006-002

LER-2006-002,

Docket Number
Event date:	04-18-2006
Report date:	06-19-2006
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v)(C), Loss of Safety Function - Release of Radioactive Material
Initial Reporting
ENS 42509	10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material
3052006002R00 - NRC Website

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3)

Event Description:

On April 18, 2006 at 1200 central standard time (CST), relay [RLY] racks [RK] RR-119 and RR-120 were identified to contain Foxboro signal conditioning modules that did not have the required safety-related quality classification. Equipment powered through these relay racks was declared inoperable. The signal conditioning modules require a classification of safety-related for electrical boundary and non safety-related for function.

Four modules were identified that did not have a safety-related classification in RR-119 and two modules were identified that did not have a safety-related classification in RR-120.

The following instrumentation and equipment powered through relay racks RR-119 (Train A) and RR-120 (Train B) were declared inoperable: Reactor coolant system subcooling [TI], reactor vessel level [LI] indication system, pressurizer safety valve outlet temperature [TI], pressurizer power operated relief valve outlet temperature [TI], and shield building ventilation damper control [CDMP].

The station entered a 12-hour Technical Specification (TS) action statement for both trains of the shield building ventilation system being declared inoperable. This TS was exited at 1611 CST on April 18, 2006 with return to service of RR-120. A seven day action statement for one train of the shield building ventilation system being inoperable was exited with RR-119 returned to service at 2128 CST on April 18, 2006.

The relay racks were declared inoperable due to non safety-related fuses [FU] and cables [CBL] installed in six of the signal conditioning modules in these relay racks. The instruments associated with the six modules were not found in TS required instruments or alarms. The concern was that a downstream failure on the non safety­ related modules could impact safety-related equipment since it did not have safety-related fault protection.

This event was reported under 10 CFR 50.72(b)(3)(v)(C) "Any event that at the time of discovery could have prevented the fulfillment of the safety function of systems that are needed to control the release of radioactive material." Event Notification Number 42509 was made on April 18, 2006 at 1922 CST.

An extent of condition was initiated to review all relay racks. Relay racks RR-101, RR-102, RR-103, RR-104, RR-105, RR-116, RR-117, RR-118, RR-119, and RR-120 were determined to have safety classification issues. Engineering evaluated if the equipment contained inside the relay racks was properly evaluated for the safety classification assignment. The purchase orders were reviewed for proper safety classification and the work history was reviewed for proper safety classification. All discrepancies were evaluated to determine the potential impact on safety related functions. Actions were taken as necessary to upgrade the applicable modules to the proper safety classification by either returning the module to the vendor for refurbishment and recertification or replacing the module. Further evaluation determined that none of the discrepancies impacted a safety-related function.

The Foxboro modules classified as non safety-related are maintained under the same vendor manuals, which use the same part numbers, as those classified as safety-related. All the parts purchased as spares are qualified as safety-related to avoid the possibility of putting non safety-related parts in safety-related applications. The power plug [CON] and cord set, chassis, fuse, and fuse holder are the same construction as all other Foxboro "H" line series of modules.

FACILITY NAME (1) DOCKET NUMBER (2) (6)LER NUMBER PAGE (3) Kewaunee Power Station 05000305 YEAR Event Analysis and Safety Significance:

This event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) "Any operation or condition that was prohibited by the plant's Technical Specifications" and 10 CFR 50.73(a)(2)(v)(C) "Any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material.

Equipment and instrumentation important to safety that could potentially be lost were both trains of the shield building ventilation damper controls and accident instrumentation. The scenario would be for an internal electrical short to occur in a non safety-related Foxboro module in each of relay racks RR-119 and RR-120 that could cause the entire loss of safety-related power to the relay racks.

Proper functioning of the shield building ventilation system is required to establish containment integrity. TS 3.6.a states: "Containment system integrity shall not be violated if there is fuel in the reactor which has been used for power operation, except whenever either of the following conditions remains satisfied: (1) The reactor is in the cold shutdown condition with the reactor vessel head installed, or (2) The reactor is in the refueling shutdown condition.

TS Table TS 3.5-6 contains the specifications for the instrumentation declared inoperable. TS 3.5.e states:

`The accident monitoring instrumentation in Table TS 3.5-6 shall be operable whenever the plant is above hot shutdown." The basis for this is to assure there is sufficient information available to aid the operator in identification of an accident and assessment of plant conditions during and following an accident. Although this event caused some of the TS Table TS 3.5-6 instrumentation to be inoperable, operation was within the allowance of the specifications.

This is considered a safety system functional failure since this condition could have prevented the fulfillment of the safety function of systems that are needed to control the release of radioactive material.

The safety significance associated with this event is minimal. The probabilistic risk model for Kewaunee analyzes for contributions to core damage and a large early release from containment. The shield building ventilation system is not a contributor to the core damage frequency or the large early release frequency, therefore the safety significance is minimal.

Cause:

The initial results of the investigation determined that the causes of the relay rack equipment safety classification discrepancies are inaccurate asset database information and the installation of non safety­ related modules in safety-related relay racks by the use of the asset database information in the development of maintenance work orders.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3)

Corrective Actions:

1. The non safety-related signal conditioning modules for RR-119 and RR-120 were immediately replaced or unplugged.

2. An extent of condition review was performed to determine the safety-related functions of instrumentation and components powered through the relay racks and correct any discrepancies found.

3. The necessary safety classification changes to the asset database were identified and are in the process of being changed.

Similar Events:

None.