05000220/LER-2004-003

LER-2004-003, Inadequate Environmental Qualification Barrier Considerations Resulting in an Unanalyzed Condition

Docket Number
Event date:	02-25-2003
Report date:	09-13-2004
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
2202004003R00 - NRC Website

I. Description of Event

On February 25, 2003, several doors to the NMP1 Control Room and Auxiliary Control Room were breached for ventilation purposes to improve the comfort level for Operations personnel while the Control Room Air Conditioning System was out of service for maintenance. Breach permits for the affected doors were generated, reviewed, approved, and issued in accordance with plant procedures. Since the doors were active barriers in the Control and Auxiliary Control Room pressure boundary, NMP1 entered into a 7 day Limiting Condition for Operation (LCO) action ,per Technical Specification Section 3.4.5, "Control Room Air TreatmentS�ystemTwo of the doors, D1Oand D109,–."� L�— communicate directly with the Turbine Building.

After the doors had been opened, questions were raised concerning the Environmental Qualification (EQ) implications for the Control Room area as a result of atmospheric communication with the Turbine Building. The Control Room and Auxiliary Control Room at NMP1 are required to be maintained as mild environments for Control Room habitability and electrical equipment operability purposes. Per plant engineering design standards, the EQ zones outside the Control Room and Auxiliary Control Room (TB277N26 and TB261N22 respectively) are considered harsh environments due to a postulated High Energy Line Break (HELB). With doors D107 and D109 breached for ventilation, the Control Room and Auxiliary Control Room atmosphere was in direct communication with the potentially harsh environment of the Turbine Building.

Doors D107 and D109 were closed, restoring the Control Room and Auxiliary Control Room EQ boundary. A review indicated that breach permits had been processed and evaluated in accordance with NMP1 procedures; however, NMP1 procedures did not include EQ considerations as a design attribute to be considered when evaluating and processing breaches.

II. Cause of Event

The direct cause of the event was procedural inadequacy since NMP1 procedures did not include EQ implications in breach evaluations. An apparent cause evaluation traced this procedural inadequacy to less than adequate EQ program implementation. When the site EQ program was initially established, EQ considerations were incorporated into Nine Mile Point Unit 2 (NMP2) breach procedures but were not incorporated into NMP1 breach procedures. This initial omission carried forward through subsequent procedure revisions.

A contributing apparent cause was that personnel performing NMP1 breach evaluations did not have adequate cross­ disciplinary training in the EQ program and did not have good understanding of the NMP1 EQ program or its requirements. As a result, it was not recognized that a requirement for EQ review should have been included in the NMP1 breach evaluation process.

Ill. Analysis of Event The event resulted in no actual equipment inoperability or loss of safety function. However, in the unlikely event of a HELB affecting Turbine Building EQ zones TB277N26 and TB261N22 concurrent with doors D107 and D109 being maintained open as described, a mild environment within the Control Room could not have been assured. This resulted in an unanalyzed condition in which neither Control Room habitability nor operability of equipment within the Control Room were assured. The condition, therefore, represents an event or condition that resulted in the nuclear power plant being in an unanalyzed condition that significantly degraded plant safety, as described in 10 CFR 50.73(a)(2)(ii)(B).

An assessment determined that the procedural inadequacy identified as the direct cause of the event had existed since the inception of the EQ program for NMP1. Previous NMP1 breach permit evaluations therefore would not have routinely included EQ considerations.

Ill. Analysis of Event (continued) The event was not initially recognized as reportable. Subsequent corrective action program evaluation assessed the event as reportable.

1V_Corrective 1. Doors D107 and D109 were closed, reestablishing the HELB barrier between the affected EQ zones.

2. Plant procedures were revised to include EQ considerations in the NMP1 breach permit process.

3. An assessment was conducted of the breach review procedure for other potential deficiencies. Other "permit" type procedures were also reviewed to assure that no applicable EQ considerations were omitted.

4. Personnel involved in evaluating breach permits have been briefed on the requirement to include EQ considerations in NMP1 breach permit review.

In addition to the above, a comprehensive assessment of EQ program scope and implementation is being conducted within the provisions of the site corrective action program.

A. Failed Components:

None

B. Previous similar events:

_ None — - C. Identification of components referred to in this Licensee Event Report:

Components� IEEE 805 System ID�IEEE 803A Function Control Room� NA� None Turbine Building� NM� None Control Room Air Conditioning System�VI� None Door� NA� DR