ML20206Q441
| ML20206Q441 | |
| Person / Time | |
|---|---|
| Site: | Portsmouth Gaseous Diffusion Plant |
| Issue date: | 05/12/1999 |
| From: | Jonathan Brown UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GDP-99-2024, NUDOCS 9905190130 | |
| Download: ML20206Q441 (6) | |
Text
IUSEC A Global Energy Company May 12,1999 GDP 99-2024 U. S. Nuclear Regulatory Commission Attention: Document Control Desk i
Washington, D.C. 20555-0001 Portsmouth Gaseous Diffusion Plant (PORTS)
Docket No. 70-7002 Event Report 99-07 Pursuant to Safety Analysis Report (SAR), Section 6.9, Table 6.9-1, J(2), Enclosure 1 provides the required 30-day written Event Report for an event involving a high condensate level shutoff actuation at the Portsmouth Gaseous Diffusion Plant. Enclosure 2 is a list of commitments made in the report.
Should you require additional information regarding this event, please contact Scott Scholl at (740) 897-2373.
Sincerely, h
. Morris Brown General Manager l
Portsmouth Gaseous Diffusion Plant i
Enclosures:
As Stated cc:
NRC Region Ill Office NRC Resident Inspectors - PORTS 9905190130 990512
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PDR ADOCK 07007002
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PDR P.O. Box 800, Portsmouth, OH 45661 Telephone 740-897-2255 Fax 740-897-2644 http://www.usec.com Omces in Livermore, CA Paducah, KY Portsmouth, OH Washington, DC
GDP 99-2024 Page 1 of 4 Event Report 99-07 Description of Event On April 12,1999, at approximately 0115 hours0.00133 days <br />0.0319 hours <br />1.901455e-4 weeks <br />4.37575e-5 months <br />, X-344 autoclave (AC) #2 was in Mode II heating a 48" Uranium Hexaflouride (UF.) cylinder when the audible alarm for steam shutdown was received. Operators responding to the alarm found the "A" and "B" condensate alarm lights illuminated indicating the high condensate level shutoff (llCLS) safety system had actuated. Steam supply block valve PSV-133 was verified to be in the closed position, stopping steam flow to the autoclave as designed. A IICLS actuation is reportable in accordance with the Safety Analysis Report (SAR), Table 6.9-1, J(2).
The condensate shutoff system is provided to prevent over pressurization or a nuclear criticality in an autoclave following a postulated UF release. Excess water is undesirable in the event of a UF.
6 release from the cylinder that could cause either high Hydrogen Fluoride pressure as the result of the reaction between UF. and water or the excessive moderation of an unsafe mass of uranium thereby causing a criticality within the autoclave. The system function is to detect either a drain line plug or restriction and to shutoff the steam flow to the autoclave.
Cause of Event j
On November 23,1998, AC #2 was removed from service for various maintenance deficiencies and was returned to service on April 7,1999. During this time there was considerable work done inside the autoclave shell. The work done inside the shell would disturb existing equipment thereby generating more rust than normal autoclave operation and would increase the potential for foreign material to accidentally enter the condensate drain.
Prior to the HCLS actuation on April 12,1999, chemical operations personnel assigned to the X-344 building, cleaned the AC #2 interior shell on April 6,1999. On April 7,1999, maintenance cleaned the condensate strainer on AC #2 and discovered the strainer was 90% restricted. Operations personnel then performed a post maintenance test (PMT), consisting of a two hour steam run to flush any residual debris that might have been disturbed by the shell cleaning into the strainer. During this PMT the HCLS safety system actuated. Following the PMT, maintenance removed the strainer and discovered the strairer was clean. The condensate lines were then flushed during boroscoping activities to remove the rust that was believed to have blocked the condensate drain line upstream of the strainer. Maintenance personnel who were involved with the strainer cleaning reported a large amount of debris was flushed out of the flush leg of the strainer during this evolution. Boroscoping activities discovered a piece of wire insulation approximately 1/4 inch in diameter and 6 inches in length, a piece of Teflon tape approximately 7 inches in length, and approximately one half gallon bucket of rust. These were removed from the autoclave condensate lines.
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j GDP 99-2024 Page 2 of 4 Event Report 99-07 The direct cause for the HCLS actuation on April 12,1999, was debris accumulation in the strainer and foreign material impeding flow through the temperature control valve (TCV). Following the event, maintenance inspected the strainer and discovered that it was 50% restricted with debris, while the flush leg on the strainer was completely full of debris. During boroscoping of the condensate line on AC #2, it was discovered that a small piece of wood approximately 3/16 inch
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diameter by 3 inches long was lodged in the TCV. Maintenance also removed the bucket type steam trap on AC #2 and found that it contained approximately one half cup of rust.
The root cause for the HCLS safety system actuation was inadequate cleaning of the interior of the autoclave shell following maintenance. Prior to the HCLS actuation, AC #2 was cleaned by chemical operators on April 6,1999. An inspection of the autoclave interior shell was conducted following this event. The inspection revealed the presence of a large amount of rust which indicated that the April 6,1999, cleaning was inadequate. Interviews performed with the two chemical operators who cleaned the autoclave revealed that the operators were new to the X-344 building.
The operators indicated that they had not cleaned the interior of an autoclave before and had not received any instructions on how the autoclave should be cleaned.
Cleaning of the autoclave interior was initiated as a result of past HCLS actuations. The last HCLS actuation due to debris accumulation occurred on December 19,1997. The previous chemical operators who performed interior shell cleaning were more experienced due to the multiple cleaning evolutions they had performed. The training program has treated autoclave cleaning as a " skill of the craft" activity which would not require formal task development. This event revealed a weakness in the training program that resulted in chemical operators being assigned to perform autoclave
- cleaning without an adequate understanding of the importance of the task or how the task was to be done.
j A contributing cause for the HCLS safety system actuation was inadequate guidance on flushing and boroscoping activities. During the boroscoping activities on April 7,1999, water was flushed down each section of piping to remove any loose debris caused by the boroscope apparatus. During the flushing process, the strainer screen was removed, which allowed a small piece of wood to float past i
the clean out port on the strainer and work its way into the TCV. Had the strainer been in place i
during this flushing activity, the piece of wood would have been prevented from migrating to the TCV. Additional administrative controls need to be developed to require that the strainer be installed during flushing activities.
A review of Foreign Material Exclusion (FME) requirements was also conducted. Procedure XP2-GP-GP1030, " Work Control Process" directs the maintenance planner to identify FME requirements for safety system work but does not require FME for non-safety work that could be conducted inside the autoclave shell. While procedure XP3-GP-GP1070, " Foreign Material Exclusion" does not limit FME to safety systems, it does not require FME for autoclave interior work. A review of autoclave work packages and interviews with maintenance personnel revealed
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GDP 99-2024 Page 3 of 4 Event Report 99-07 that FME is not always applied to autoclave interior shell work. This is contrary to direction that i
was previously provided to maintenance planners as a result of a previous IICLS actuation that was
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caused by foreign material. This previous direction stated, " Anytime work is performed inside the 1
autoclaves, the requirements of FME will be applied." This direction was provided informally, however, and was not incorporated into procedures.
I Work packages for work done on the interior shell of AC #2 were reviewed. Most of these packages were for non-safety components. It was evident from the review of work packages and interviews with maintenance planners and maintenance first line managers that FME requirements were not being followed and that there is a lack of understanding of when FME should be implemented and to what degree.
Corrective Actions 1.
On May 6,1999, stand down training on foreign material exclusion practices with operations / chemical operators / maintenance personnel within the X-340 complex who perform work inside autoclaves was performed.
2.
On April 15,1999, as a compensatory action, a section policy was issued to X-340 complex operations personnel to provide additional administrative controls for FME. One of these controls includes inspection of the interior of an autoclave by an FLM for foreign material including rust.
3.
By June 11, 1999, stand down training on foreign material exclusion practices will be performed with appropriate maintenance personnel that were not previously trained.
4.
By July 30,1999, procedure XP4-TE-TE2700 " Foreign Material Exclusion at the X-340 Complex Autoclaves" will be revised to direct cleaning and removal of foreign material from autoclave shells.
5.
By August 31, 1999, develop formal systems approach to training base module and incorporate into training requirement matrix or qualification standard for cleaning of the autoclave interior shell in accordance with the requirements and action steps added to XP4-TE-TE2700 " Foreign Material Exclusion at the X-340 Complex Autoclaves."
6.
By September 31,1999, train applicable chemical operators on task of cleaning shell and removing foreign material prior to strainer cleaning.
GDP 99-2024 Page 4 of 4 Event Report 99-07 7.
By October 31, 1999, procedure XP4-TE-UH3770 "X-344 Off Normal Autoclave Operations" and XP4-TE-FD3770 "X-342/343 Off Normal Autoclave Operations" will be revised to ensure the strainer is not removed during flushing operation when the condensate line is being boroscoped to prevent foreign material from becoming lodged in the TCV or steam trap.
8.
By October 31,1999, procedure XP3-GP-GP1070 " Foreign Material Exclusion" will be revised to further clarify when FME is to be implemented.
9.
By October 31,1999, procedure XP2-GP-GP1030 " Work Control Process" will be revised to provide direction for implementing FME controls consistent with XP3-GP-GP1070
" Foreign Material Exclusion."
10.
By January 5,2000, Planners / Maintenance personnel whosejob task requires FME will be trained on FME practices.
Extent of Exposure ofIndividuals to Radiation or Radioactive Materials Based on health physics survey results, there was no evidence of a release of radioactive material during this event.
Lessons Learned i
This event revealed that relying on " skill of the craft" instead of formal guidance and training can lead to inconsistent results. This is a special concem when a relatively simple task such as cleaning can result in challenging safety systems if not performed correctly. Before designating " skill of the craft" to an activity instead of formal training, the task performer must understand what constitutes acceptable performance.
G es<'*
GDP 99-2024 Page1of1 Event Report 99-07 List of Commitments i
1.
By June 11,.1999, stand down training on foreign material exclusion practices will be performed with appropriate maintenance personnel that were not previously trained.
2.
By July 30,1999, procedure XP4-TE-TE2700 " Foreign Material Exclusion at the X-340 Complex Autoclaves" will be revised to direct cleaning and removal of foreign material from autoclave shells.
j 3.
By August 31, 1999, develop fonnal systems approach to training base module and incorporate into training requirement matrix or qualification standard for cleaning of the autoclave interior shell in accordance with the requirements and action steps added to XP4-TE-TE2700 " Foreign Material Exclusion at the X-340 Complex Autoclaves."
4.
By September 31,1999, train applicable chemical operators on task of cleaning shell and i
removing foreign material prior to strainer cleaning.
l 5.
By October-31, 1999, procedure XP4-TE-UH3770 "X-344 Off Normal Autoclave Operations" and XP4-TE-FD3770 "X-342/343 Off Normal Autoclave Operations" will be revised to ensure the strainer is not removed during flushing operation when the condensate line is being boroscoped to prevent foreign material from becoming lodged in the TCV or steam trap.-
6.
By October 31,1999, procedure XP3-GP-GP1070 " Foreign Material Exclusion" will be revised to further clarify when FME is to be implemented.
7.
By October 31,1999, procedure XP2-GP-GP1030 " Work Control Process" will be revised to provide direction for implementing FME controls consistent with XP3-GP-GP1070
" Foreign Material Exclusion."
8.
By January 5,2000, Planners / Maintenance personnel whose job task requires FME will be trained on FME practices.
- Regulatory commitments contained in this document are listed here. Other actions listed in this submittal are not considered regulatory commitments in that they are either statements or actions completed, or they are considered enhancements to USEC's investigation, procedures, or operations.