ML20149D325
| ML20149D325 | |
| Person / Time | |
|---|---|
| Site: | Paducah Gaseous Diffusion Plant |
| Issue date: | 07/10/1997 |
| From: | Polston S UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GDP-97-1019, NUDOCS 9707170093 | |
| Download: ML20149D325 (7) | |
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United States Enrichment Corporation 1'
q' Paducah Site Office P.O. Bos 1410
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Paducsh, KY 42001 4 -
Tel: 502 4415803 Fax: 502 441-5801 July 10,1997 United States Nuclear Regulatory Commission SERIAL: GDP 97-1019
. Attention: Document Control Desk Washington, DC 20555-001 Paducah Gascous Diffusion Plant (PGDP)- Docket No. 70-7001 - Event Report ER-97-12 Pursuant to 10 CFR 76.120(c)(2), enclosed is the required 30-day written report for the loss of the West Normetex pump UF. release detection system in C-310. This was initially reported on June 15,1997 (NRC No. 32489). Enclosure 2 is a list of commitments made in this report.
Should you require further information on this subject, please contact Bill Sykes at (502) 441-6796.
Sincerely, teve olston General Manager Paducah Gaseous Diffusion Plant SP:WES:JNil:mel Enclosures (2) cc:
NRC Region 111 NRC Senior Resident Inspector, PGDP
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- Docket No. 70-700I a
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' Event Report '
l ER 97-12 IBACKGROUND Technical Safety Requirement (TSR) 2.3.4.3 requires the Normetex pump UF release detection and isolation system to be operable in Mode 2, a mode which involves UF being withdrawn 6
from the cascade, compressed, condensed, and drained into UF. cylinders. On June 13,1997, the C-310 West Normetex pump UF release detection and isolation system was inadvertently-disabled while the West Normetex pump was in Mode 2. The problem occurred during the
- performance of an annual surveillance of the C-310 East Normetex pump. The East Normetex pump surveillance requires the instrumentation and controls (1 & C) technician to lin and land -
programmable controller output leads associated with the East Normetex pump. During the performance of the surveillance, the technician also lined and landed the output leads associated with the West Normetex pump. The lining and landing ofleads on the West Norr: etex pump effectively caused the West Normetex pump UF. detection and isolation system to be inoperable.
The problem was discovered during the investigation of an unexpected response to a routine smoke test. Pursuant to 10 CFR 76.120 (c) and (d), a notification was made of the event at 1600 7
on June 15,1997.
DESCRIPTION OF EVENT On June 14,1997, at 1355, operators were conducting a routine smoke test of the West Normetex pump UF release detection system, as required by Operations Long Term Order No. 310-96-013.
This order requires smoke testing of the UF. release detection system twice per shin by smoking i
a head on the standby pump. If the release detection system for the standby pump is inoperable,
- the head over the on-stream pump is to be smoked. The UF. release detection system is designed to alarm when any head fires and to shut the pump down and close the inlet and outlet block valves when any two adjacent heads are actuated. When operators smoked the single head YE-255-7 during the routine test, they received not only a " Trouble Alarm," as expected, but also
'a "Normetex Shutdown Alarm" (abnormal). Additionally, the West Normetex oil pump shut down (abnormal).
l The Plant Shin Superintendent (PSS), the front line manager, and the system engineer wx j
' notified of the abnormal sequence of events. Testing was repeated by smoking c'her tads The J
results were the same, with the annunciation of the same two alarms and the shut %w v3e
- West Normetex oil pump. During troubleshooting, the system engineer disc'ovbed that leads
- TO-2-1 and TO-2-2 were reversed on programmable controller UUC-255-B. Roc rShese e
leads would cause the single head firing to result in the shutdown of the oil pump. Interviews q
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with I & C techmcians revealed that these leads had been reversed during the annual surveillance
'of the East Normetex pump, which was completed on June 13,1997.
The surveillance of the East Normetex pump was completed under work package R 9703770-0, using procedure CP4-GP-lM4126, "C-310 Process Gas Leak Detection East Normetex Pump Functional Test - Safety _ System." Procedure CP4-GP-IM4126 includes sections for performing functional tests on the "A" (Section 8.2) and the "B" (Section 8.3) trains of the signal conditioner / controller. During the functional test of the signal conditioner / controller of Train A,
- Procedure step 8.2.2 of CP4-GP-IM4126 requires the I & C technician to
" Lift leads fram terminals I and 2 (TO-1-1 & TO-1-2) on left digital output module of UUC-255B as shown on Appendix B, Programmable Controller UUC-255B A/B Right and Left Output Module Terminal Locations."
This step also contains the following checkoff:
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. UUC-255B: Left output tnodule terminals 1 and 2 leads lined.
The technician indicated that he lifted four leads, instead of two leads as the procedure required.
He lifted the terminal 1 and 2 leads on both the left output module and on the right output.
module. Linin 2 these leaJ., on the right output module disabled channel B on the West Normetex pump UF. detection system while the West Normetex pump was on-stream in mode 2; channel A of the West Normetex UF. detection was still functional. Step 8.2.15 of the procedure required the relanding of the UUC-255B left output module terminals 1 and 2. The step also contains both a checkoff and an independent verification of completion. The technician j
relanded the left output module terminals 1 and 2 correctly, signed off on their completion, and had them independently verified. However, he also relanded the right output module terminals 1 and 2 in reverse order, even though the leads were marked as "1" and "2." The independent verification of the relanding would not have been expected f.o catch the reversing of the leads on the right output module, since it was only intended to verify that the left output module terminals had been relanded properly, While performing Section 8.3 of the procedure which covers the functional test of the B train,
. terminal 1 and 2 leads were also lifted and relanded on both output modules on UUC-255-A, although the procedure requires the leads to be lifted /relanded 'on the left output module only.
. detection system while the. West Normetex pump was onistream in mode 2. For a period of time, i
estimated to be less than 25 minutes' channel A was disabled (while the leads were lifted), at the same time that channel B of the controller was wired with terminals I and 2 reversed.
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- Docket N.o. 70-7001 Page 3 of 5 The action step to lift leads references Appendix B of this procedure which contains a diagram showing the configuration of the programmable controller. The diagram designates the left/right input and output, as well as the numbering of the terminals. The I & C technician indicated that i
he interpreted the procedure step of" Lift leads fcom terminals 1 and 2 (TO-1-1 & T0-1-2) on len
. digital output module..." as lift leads from terminal I and terminal 2 on both output modules.
The I & C technician who performed the work had nevEr done thejob before and was working alone. He was in radio contact with his front'line manager who was working upstairs in C-310 with a trainee and another I & C technician on other aspects of the surveillance.
CAUSES OF EVENT 1
A.
Root Cause The root cause of this event is failure to follow the procedure due to inattention to detail.
l The investigation team found no major problems with the procedure that would lead a person to lift /reland leads from both output modules. The " inattention to detail" in lifting leads on both output modules, instead of the left output module only, is further supported by the I & C technician's action of relanding the leads on the Channel A in the reverse 1
order, even though the leads were labeled as "1" and "2." Discipline was administered to i
the technician for failure to follow the procedure.
A B.
Contributing Causes A contributing cause of this event is a need for improvement in the labeling of the controllers. Marking / labeling was used to mark the controllers as TI-1, TO-1, TI-2, and TO-2. The terminal wires on the right controller were labeled; the left wires were not labeled, but were tie-wrapped together which maintained an acceptable order. There were no labels to indicate which pump (East or West Normetex ) was affected by each controller module. The technician indicated that he thought the left and right output modules of the controller affected two channels of a single Normetex pump. In actuality, the two output modu'es control two different Normetex pumps. Engineering issued an
- Engineering Notice to define the labeling required for the Normetex pump controllers.
Operations, with the assistance of Maintenance, will meet the labeling requirements defined in the above Engineering Notice (Completed Action No. 3 and Corrective Action No.1).
Another contributing cause relates to the training of the I & C technician and the current qualifications for this work. Although this technician had met his training requirements to be " qualified" to work on this system, that training was designed more at the component level and did not include suflicient " system" training to give him an adequate understanding of the C-310 Normetex pump UF. detection and isolation system in order i
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Docket No. 70-7001 Page 4 of 5 -
to be aware of the vulnerabilities associated with the work he was performing.
Corrective Actions No. 2 and 3 address this by creating training modules related to the
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" system" functions of the Normetex pumps and by reevaluating the qualifications for I &
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- C technicians who work on the Normetex pumps. The revised qualifications will include both enhanced training modules and a list of requirements which must be satisfied befor_e
. performing certain tasks alone. As a generic issue, Maintenance will identify other TSR systems, structures,and components (SSCs) that require special system skill training and qualifications lists..' A schedule will be developed to enhance the system skills training and qualification lists for the identified TSR SSCs (Corrective Action No. 4).
A third contributing cause is the lack of control in thE lifting ofleads that might impact operable safety systems. As an immediate compensatory measure, Maintenance issued i
Maintenance Functional Directive No.97-021 which was disseminated to affected personnel via required reading / crew briefings (Completed Actions No. I and 2). This directive provides the requirements for a walk-through with the craft person prior to initiating maintenance work involving TSR surveillances or work that may potentially
' impact an operable interfacing TSR SSC. The directive also requires signoffs for self-checking and independent verification of any work step that could affect functionality of TSR SSCs. The requirement for independent verification where TSR SSCs could be affected will be incorporated into current maintenance TSR surveillance procedures (Corrective Action No. 5).
Although not a cause of the event, an area of concem to the investigation team was the delay in j
the awareness of the problem. Logs indicate that the annual surveillance, which resulted in the reversed terminal leads on the West Normetex pump, was completed at 1114 on June 13,1997.
By 1510, the East Normetex was back onstream and by 1545 the West Normetex was shut down.
j Therefore, the smoke tests required to be completed at 2000,0200, and 0800 on a single UF6 detection head associated with the offstream West Normetex pump would have been expected to shut down the West Normetex oil pump, as occurred at the 1400 smoke test. Building logs and interviews with operators indicated that no abnormal events occurred during the performance of i
these three smoke tests. However, vibration data charts indicate the oil pump may have shut down at 0800 and restarted. The cause of this discrepancy could not be determined.
CORRECTIVE ACTIONS '
A.-
Completed Corrective Actions
- 1. On June 19,1997, Maintenance issued Functional Directive No.97-021.
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- 2. On June 20,1997, field I & C personnel were briefed on Functional Directive No.97-021 through required reading / crew briefings.
- 3. On June 26,1997, Engineering issued an Engineering Notice to define the labeling required for the Normetex pump controllers.
B.
Corrective Actions Planned
- 1. By August 7,1997, Maintenance will meet the labeling requirements defined in the Engineering Notice in Con:pleted Action No. 3.
- 2. By August 30,1997, Training and Procedures will develop training modules related to the " system" functions of the Normetex pumps.
- 3. By January 31,1998, Maintenance will enhance the system skill training and the qualification lists for I & C technicians who work on the Normetex pumps.
- 4. By December 1,1997, Maintenance will identify other TSR SSCs that require special i
system skill training and qualification lists and will develop a schedule to enhance the system skills training and qualification lists for the identified TSR SSCs.
- 5. By February 20,1998, Maintenance will revise their TSR surveillance procedures to include checkoffs for independent verification where TSR SSCs could be affected.
EXTENT OF EXPOSURE OF INDIVIDUALS TO RADIATION OR TO RADIOACTIVE MATERIALS I~
There was no exposure to individuals to radicion or to radioactive materials during the time that UF detection system was inoperable.
LESSONS LEARNED The risk of personnel making mistakes while performing a task for the first time with an inhand -
procedure can be reduced with (a) good labeling of equipment; (b) independent verification of key action steps; and (c) an understanding of the system functions achieved'through special system skill training and qualification.
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Page1ofI List of Commitments ER-97-12 1.
By August 7,1997, Maintenance will meet the labeling requirements defined in the Engineering Notice in Completed Action No. 3.
2.
. By August 30,1997, Training and Procedures will develop training modules related to the " system" functions of the Normetex pumps.
3.
By January 31,1998, Maintenance will enhance the system skill training and the qualification lists for I & C technicians who work on the Normetex pumps.
4.
By December 1,1997, Maintenance will identify other TSR SSCs that require special system skill training and qualification lists and will develop a schedule to enhance the system skills training and qualification lists for the identified TSR SSCs.
5.
By February 20,1998, Maintenance will revise their TSR surveillance procedures to include checkoffs for independent verification where TSR SSCs could be affected.
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