ML17146A287
| ML17146A287 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 09/16/1985 |
| From: | Trager E NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | |
| Shared Package | |
| ML17146A286 | List: |
| References | |
| TASK-AE, TASK-T511 AEOD-T511, NUDOCS 8603110531 | |
| Download: ML17146A287 (6) | |
Text
AEOD TECHNICAL REVIEW REPORT*
UNIT:
DOCKET NO.:
LICENSEE:
NSSS/AE:
Susquehanna 1
50-387 Pennsylvania Power and Light GE/Bechtel TR REPORT NO.:
AEOD/T511 DATE: September,16, 1985 EVALUATOR/CONTACT:
E. A. Trager
SUBJECT:
TECHNICIANS PERFORM WORK ON WRONG CONTROL ROD DRIVE MECHANISM EVENT DATE:
February 22, 1985
SUMMARY
During work to remove a control rod drive (CRD) mechanism, the two tech-nicians began removing flange bolts from the wrong CRD.
This failure to maintain the correct identity of the CRDs appears to be the result of factors related to lack of experience of the licensee.
Corrective action by the licensee was appropriate and thorough.
No further AEOD action is necessary at this time.
DISCUSSION Potentially significant events can occur as the result of human error in-volving the wrong unit, train, or component.
One such event was reported in the Region I Daily Report for Susquehanna 1 as follows:
During removal of the second control rod drive (CRD) at 12:40 a.m.
February 22, six out of eight flange bolts were inadvertently removed from a CRD that was not uncoupled 'and not designated for removal.
Two fuel assemblies surrounded the associated CRD.
The error occurred when the workers, after completing an uncoupling verification, became disoriented after exchanging tools for the next step in the procedure.
The correct rod was identified with a blue maintenance tag and the absence of a rod position indication probe (PIP) but this was not reverified once unbolting commenced.
The workers realized they were on the incorrect rod when the removal strongback would not fit.with the PIP installed.
The workers immed-iately informed the removal supervisors and the appropriate LCO was entered.
All CRD removal operations were suspended pending completion of the licensee's review.
The partially unbolted CRD has been restored.
Because the error was discovered and the event concluded before an unsafe condition was established, this event was not reportable by LER.
- However, because the event had characteristics similar to other events involving the wrong unit, train, or component, a technical review was performed to further investigate the cause(s) of the event.
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Resident Inspection Report 50-387/85-09, dated April 16,
- 1985, gave further details on this event as follows:
During the day shift on February 21, CRD 02-23 was uncoupled from its control rod and released by operations for removal.
On the following night shift, the workers underneath the reactor vessel in bubble suits, after completing an uncoupling verification on CRD 02-23, became disoriented after exchanging tools for the next step in the procedure, and began removing the flange bolts for CRD 02-27.
The super visor was unable to detect the error on his remote video monitor due to the limited camera coverage.
Six out of eight flange bolts were removed before the workers realized they were working on the incorrect mechanism.
The crew noted CRD 02-27 was incorrect because the position indicator probe (PIP) was still connected.
The PIP had been previously removed from CRD 02-23 to facilitate the installation of the removal strongback.
The crew immedi'at'ely reported the error to their supervisor, who relayed the information to the Shift Supervisor.
LCO 3.9. 10.2 was entered because fuel remained in positions 01-28 and 03-26, while bolts were removed on CRD 02-27.
The six bolts were replaced and further CRD removal evolutions were suspended by the shift supervisor.
The licensee approved procedure change approval form (PCAF) 1-85-0145 on February 22, which added a caution in maintenance procedure MT-055-003, Control Rod Drive Removal, to reverify the CRD serial number with supervision via the communication system prior to unbolting the flange.
Additionally, stricter controls were placed on the commun-ication requirements between the supervisor and worker, so the super-visor could read the procedural steps to the workers and the workers could keep the supervisor informed of the work completed.
Training sessions were held to discuss the procedure revisions and the previous event.
Streamers were also placed on the released CRD's to aid in their identification.
After completion of the corrective actions the licensee continued with CRD replacements on February 25, 1985 Discussions with the resident inspectors (SRI Rick Jacobs and RI Loren Plisco) helped further clarify the event.
There were a number of contributing factors to the event:
Because of lack of experience (this was the second CRDM to be removed during the first Susquehanna 1 refueling) and because of concerns about radiation exposure, the technicians may have been distracted.
In addition, they were dressed in "bubble suits" and working in cramped quarters.
Finally, it is likely the technicians had been working much overtime during the refueling outage.
Although the supervisor was monitoring (via video monitor) the work of the technicians, he was actually doing little to help insure the work was carried out correctly.
Because of close quarters the
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supervisor could not actually see what component was being worked on.
The licensee's corrective action correctly focused on this problem.
The procedure was changed to require the supervisor to read the procedure steps and the technicians to describe the work in progress, including reverification of CRD identity prior to unbolting.
Although training for CRD removal was performed on a mock-up, the training may not have been sufficiently realistic.
The mock-up consisted of a single CRD mechanism, while the actual work took place beneath 185 mechanisms.
The subsequent use of colored streamers would help to identify CRDs that were uncoupled and ready to be removed.
Following this event the licensee experienced no further problems during CRD removal operations.
FINDINGS AND CONCLUSIONS This event was probably the result of factors related to the lack of experience of the licensee.
The licensee's corrective actions in this case are considered to be appropriate and thorough.
No further action on'his item is considered appropriate.
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