05000499/LER-2005-006
| Docket Numbersequential Revmonth Day Year Year Month Day Yearnumber No. 05000 | |
| Event date: | 10-18-2005 |
|---|---|
| Report date: | 2-0-2005 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4992005006R00 - NRC Website | |
I.�DESCRIPTION OF REPORTABLE EVENT
A. REPORTABLE EVENT CLASSIFICATION
This event is reportable pursuant to 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications.
B. PLANT OPERATING CONDITIONS PRIOR TO THE EVENT
Unit 2 was shutdown and defueled at the time of discovery.
C. STATUS OF STRUCTURES, SYSTEMS, OR COMPONENTS THAT WERE
INOPERABLE AT THE START OF THE EVENT AND THAT CONTRIBUTED TO THE
EVENT
There were no structures, systems, or components that were inoperable at the start of the event that contributed to the event.
D. NARRATIVE SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE
TIMES
On October 18, 2005 at approximately 17:33, while performing a lubrication and inspection on valve 2-SI-MOV-0019C (SI-19C), Low Head Safety Injection Train C to Loop 2C Hot Leg Isolation Motor Operated Valve (MOV), the actuator motor was discovered with ordinary pipe plugs installed instead of the two required T-drains.
During the subsequent inspection of other Unit 2 MOVs, valve 2-RA-MOV-0003 (RA-03), inside return isolation valve for Containment radiation monitor RT-8011, was discovered to have one ordinary pipe plug and one T-drain installed rather than the two required T-drains. This condition makes the valves inoperable and constitutes a Technical Specification violation. The purpose of the T-drains is to facilitate draining condensation from the motor in a harsh environment; hence, they are required as part of the motor's environmental qualification.
T-drains are ordinary pipe plugs with a drain path drilled up the plug centerline to the square head of the plug with an intersecting drain path drilled perpendicular to the plug centerline through two opposite faces of the square head.
- E.�THE METHOD OF DISCOVERY OF EACH COMPONENT OR SYSTEM FAILURE,
OR PROCEDURAL OR PERSONNEL ERROR
The T-drains were discovered to be missing in SI-19C during a lubrication and inspection activity. The T-drain missing from RA-03 was discovered during an extent of condition inspection after the SI-19C discovery.
II.�COMPONENT OR SYSTEM FAILURES
A. FAILURE MODE, MECHANISM, AND EFFECTS OF EACH FAILED COMPONENT
There were no failed components.
B. CAUSE OF EACH COMPONENT OR SYSTEM FAILURE
There were no failed components.
C. SYSTEMS OR SECONDARY FUNCTIONS THAT WERE AFFECTED BY FAILURE
OF COMPONENTS WITH MULTIPLE FUNCTIONS
There were no failed components.
D. FAILED COMPONENT INFORMATION
There were no failed components.
III.�ANALYSIS OF THE EVENT
A. SAFETY SYSTEM RESPONSES THAT OCCURRED
Not applicable; the condition was discovered during planned maintenance.
B. DURATION OF SAFETY SYSTEM TRAIN INOPERABILITY
When the discrepancy was discovered, the paint on the pipe plugs installed in the SI-19C motor appeared to be intact (i.e., it appeared that the plugs had not been disturbed since the motor was painted at the factory). If ordinary pipe plugs were installed instead of T-drains at the factory, this condition has existed since motor replacement in March 1994.
NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (1-2001) 2. DOCKET�11. FACILITY NAME 6. LER NUMBER 3. PAGE 2005�006 RA-03 was refurbished in March 1994 and it can only be postulated that the fact that there was only one T-drain installed in the motor was missed at that time.
C.�SAFETY CONSEQUENCES AND IMPLICATIONS This event is significant because the absence of T-drains in SI-19C make the valve inoperable per Technical Specifications 3.5.2 and 3.5.3. This event is also in non- conformance with the Generic Letter 89-10/96-05 Motor Operated Valve Program.
SI-19C is a normally-closed MOV that is opened by a manual signal during transfer to the hot-leg recirculation phase of loss of coolant accident (LOCA) mitigation. This allows the Safety Injection System (SIS) to inject borated coolant from the Containment sumps into a reactor coolant hot-leg to establish flow through the core to prevent boron precipitation if the LOCA is a cold-leg break. The first step in the procedure for transferring to hot-leg recirculation is to check that three SI trains are operable and the second step is to energize and open the hot-leg injection valve. If SI-19C does not open at this step, the operator then selects another train to establish hot-leg recirculation. Therefore, if the following events were to occur:
- plant operating at 100% power instead of being shutdown, cooled down, and depressurized
- large-break cold-leg LOCA
- SI-19C failed to open on demand then either Train A or Train B would be lined-up for hot-leg recirculation. Thus, the failure of SI-19C to open would have no safety consequences.
RA-03 is a normally-open, inside Containment isolation MOV for the return from Radiation Monitor RT-8011 to the Containment atmosphere. The safety function of RA-03 is to close on an SI signal, a manual Phase A isolation signal, a high alarm on either of two RCB purge radiation monitors, or a manual containment spray actuation.
Two Containment isolation valves are provided in series in the return line because the radiation monitoring system associated with RA-03 is connected directly to the Containment atmosphere. Therefore, if the following events were to occur:
- plant operating at 100% power instead of being shutdown, cooled down, and depressurized
- large break LOCA
- RA-03 failed to close on demand NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (1-2001) 2. DOCKET1. FACILITY NAME 6. LER NUMBER 3. PAGE 2005 006 then RA-06 (the redundant outside Containment return isolation valve for RT-8011) would close and maintain Containment integrity. Thus, the failure of RA-03 to close would have no safety consequences.
IV. CAUSE OF THE EVENT
The exact root cause of the T-drains not being installed in SI-19C cannot be determined. The corrective actions resulting from LER 93-008, a previous occurrence of missing MOV T-drains, were inadequate to ensure that subsequent maintenance performed on the motors would include installation of the T-drains (i.e., ineffective corrective actions).
The root cause of the T-drains not being discovered missing in these two valve actuators since 1994 is the fact that instructional guidance did not emphasize the criticality of validating T-drains were installed when checking the T-drains as part of the "lube and inspect" activity.
Assumptions were made that the T-drains were installed following completion of corrective actions associated with LER 93-008. As such, focus was placed on the aspects of functionality.
V. CORRECTIVE ACTIONS
1. Implement programmatic guidance by enhancing procedural guidance used to install motors on MOVs to require verifying T-drains are properly installed each time a motor is removed/installed on Harsh Environment MOVs (i.e., remove the option of having a T-drain inspection in the work package).
2. Revise OPMP05-ZE-0312 to require craft personnel to physically remove and inspect the T-drains on MOV motors during the course of this PM or make the step to require dual verification.
3. Conduct requalification training for MOV group craft personnel on:
- The Lessons Learned from this event
- Management expectations regarding proper use of written instructions
- The justification for Environmental Qualification requirements of the equipment they maintain 4. Include the Lessons Learned from this event in MC, Mechanical, and Electrical Maintenance requalification training.
5. Submit appropriate feedback to the Contracts Department on the performance problems of contract MOV personnel associated with this event.
6. Train contract MOV personnel prior to 1RE13 on:
- The Lessons Learned from this event.
- Management expectations regarding proper use of written instructions.
- The justification for and importance of Environmental Qualification requirements of the equipment they maintain.
7. Implement the discipline program protocol with STPNOC individuals involved.
REMEDIAL ACTIONS
1. The required T-drains were installed in SI-19C and RA-03.
2. An inspection of all accessible harsh environment MOVs in both units was completed on October 22, 2005. The Unit 1 MOVs located inside the missile barrier will be inspected during 1RE13.
VI.�PREVIOUS SIMILAR EVENTS