05000318/LER-2003-001
| Calvert Cliffs Nuclear Power Plant, Unit 2 | |
| Event date: | 02-23-2003 |
|---|---|
| Report date: | 04-23-2003 |
| 3182003001R00 - NRC Website | |
I. DESCRIPTION OF EVENT
Calvert Cliffs Nuclear Power Plant's Technical Specifications requires one door in the emergency air lock (EAL) (a containment penetration) to be closed during core alterations or during movement of irradiated fuel assemblies within the Containment Building. However, on EAL was not in the Technical Specification required status. Specifically, "daylight" was seen around a hose penetrating the EAL temporary closure device. The EAL temporary closure device can be used in place of an EAL door in Modes 5, 6, or defueled. Subsequent investigation determined that the violation occurred on February 23, 2003 at approximately 1300 when a contract employee cut through the foam sealant in the temporary closure device to install a one inch diameter oxygen hose needed to support steam generator replacement activities. The contract employee failed to recognize the requirement to maintain containment penetration closure and did not seal the area around the oxygen hose. Documentation in the plant's outage logs indicates that the oxygen hose was removed and the hole was sealed on February 25, 2003, prior to commencing core off-load activities. However, since core alterations (specifically control element assembly uncoupling) were performed on February 23, 2003 from 0955 until 1805 a condition existed that is prohibited by the plant's Technical Specifications.
This event is applicable to Unit 2 only. When the subject condition existed, Unit 2 was in Mode 6, at 0 percent power, with the Reactor Coolant System at approximately 106 degrees F and at atmospheric pressure. No other structures, systems, or components needed to shutdown the reactor and maintain safe shutdown conditions, remove residual heat, control the release of radioactive material, or mitigate the consequences of an accident, were affected by this condition.
Unit 1 was at 100 percent power and was not affected by the subject condition.
II. CAUSE OF EVENT
Contributing causes to the subject event were inadequate work packages and inadequate communications, both of which were the result of human performance errors. Specifically, the work packages were inadequate because they did not provide caution statements or adequately describe containment closure requirements necessary when performing work activities at the EAL temporary closure device penetrations. Furthermore, the site procedure containing these cautions and closure requirements was not included in the work packages. Communications were inadequate in that the requirements for containment closure were not communicated or known to the individuals performing the task. Opportunities to communicate effectively were missed during pre job briefs. As a result of these issues, the individuals failed to recognize the consequences of penetrating the foam sealant in the EAL temporary closure device.
III. ANALYSIS OF EVENT
The subject event describes a condition that was prohibited by the plant's Technical Specifications. The condition existed for a period longer than permitted by the plant's Technical Specifications (i.e., greater than the allowed completion time) therefore this licensee event report is required per 10 CFR 50.73 (a)(2)(i)(B). The subject condition, a degraded penetration, did not increase the probability of a loss of core cooling or of a fuel handling incident. There was no impact on mitigating systems if a loss of cooling had occurred. The area of the degraded penetration was too small to cause a large release. Therefore, the subject event does not result in an increase in core damage frequency or large early release frequency.
The Technical Specification requirements on containment penetration closure ensure that a release of fission product radioactivity within the Containment Building will be restricted to within regulatory limits. Containment penetration closure means that all potential escape paths are closed or capable of being closed. The containment personnel air lock and the containment outage door are potential escape paths that may be open during the movement of irradiated fuel assemblies in containment and during core alterations provided that each door is capable of being closed by a designated individual. During core alterations or movement of irradiated fuel assemblies within the Containment Building, a release of fission product radioactivity within the Containment Building will be restricted from escaping to the environment when these requirements are met. In Mode 6, the potential for containment pressurization as a result of an accident is not likely. Therefore, since there is no design basis accident potential for containment pressurization, the 10 CFR Part 50, Appendix J leakage criteria and tests are not required.
The EAL, part of the containment pressure boundary, has a door at both ends. The containment air locks, which are part of the containment pressure boundary, provide a means for personnel access. Each air lock has a door at both ends. When containment penetration closure is required, at least one door must be closed. The EAL temporary closure device may be used to replace an EAL door. The EAL temporary closure device permits installation of temporary penetrations for gas, water, and electrical cables to support outage activities in the Containment Building. The EAL temporary closure device provides an adequate barrier to shield the environment from the containment atmosphere in case of a design basis event that does not create a pressure increase inside Containment. The consequences of a fuel handling incident in the Containment Building are limited since the potential escape paths for fission product radioactivity released within Containment are limited.
The plant's safety analysis assumes that a fuel handling incident is initiated when a fuel assembly is dropped during fuel handling in the Containment Building or the spent fuel pool. The subject condition existed during control element assembly uncoupling (core alterations) only and not during the movement of irradiated fuel assemblies. The containment penetration closure requirements are applicable during performance of core alterations because a potential for a fuel handling incident exists. The subject event did not affect the method of performing CEA uncoupling as described in the Updated Final Safety Analysis Report. Therefore, the probability of a fuel handling incident was not increased. A fuel handling incident as described in the Updated Final Safety Analysis Report does not credit containment closure. Therefore, the consequences of a fuel handling incident are not increased by a small opening in the EAL temporary closure device.
IV. � CORRECTIVE ACTIONS A. Plant procedure change requests have been initiated to require installation of chains and signs at the EAL requiring notification of operations prior to entry and to require planners to include containment closure compliance steps in future work packages.
B. The existing work packages were changed to include a caution statement regarding work at the EAL during containment closure.
C. Contract personnel have been trained on lessons learned from this event and on expectations of using human performance error prevention tools.
V. � ADDITIONAL INFORMATION A. Affected Component Identification:
IEEE 803 � IEEE 805 Component or System � EllS Funct � System ID Reactor Containment Building � PEN � NH
B. Previous Similar Events:
A review of Calvert Cliffs' licensee event reports over the past several years was performed.
The review did not identify any similar reportable events where the containment penetration closure requirements were violated due to personnel error.
A review of Calvert Cliffs' issue reports over the past several years was also performed. The review identified one similar non-reportable event. Specifically, as documented in Issue Report No. IR4-015-734, contract employees installed a 1/4 inch copper tube through the Unit 2 EAL on February 21, 2003 to support steam generator replacement activities. The contract employees were unaware of containment closure requirements and failed to install isolation valves and caps. However, containment closure requirements were satisfied due to the installation of a foreign material exclusion device on the tubing end. The subsequent causal analysis identified inadequate work packages, inadequate communications, and lack of ownership as contributing factors. The condition was discovered on February 25, 2003, therefore, corrective actions were not established in time to prevent the subject event described in this licensee event report.