IR 05000373/1994006
| ML20029E821 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 05/17/1994 |
| From: | Creed J, Grobe J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20029E820 | List: |
| References | |
| 50-373-94-06, 50-373-94-6, 50-374-94-06, 50-374-94-6, NUDOCS 9405230062 | |
| Download: ML20029E821 (8) | |
Text
l U.S. NUCLEAR REGULATORY COMMISSION
REGION III
I Reports No. 50-373/94006(DRSS); 50-374/94006(DRSS)
Docket Nos. 50-373; 50-374 Licenses No. NPF-ll; NPF-18 Licensee:
LaSalle County Station, Units 1 and 2 Inspection Dates:
February 4 to April 21, 1994 Type of Inspection:
Announced, Reactive Followup on Event Date of Previous Physical Security Inspection: December 6-10, 1993 Inspector:
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de ff James R. Creed, Chief Date 5af'eguards and IR Section Approved By:
iff1 #M
fdhn A. Grnbe, Acting Cfife'T Date tKeactor Support Programs Branch Inspection Summary Inspection between February 4 and April 21. 1994 (Reports No. 50-373/94006 (DRSS): No. 50-374/94006(DRSS)
Areas Inspected:
This was a followup to an event identified on October 19,
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1993 and included a review of two Problem Identification Forms (PIF 93-01245;
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93-01482) dated December 11, 1993 and January 29, 1994 respectively. The event involved the discovery of foreign particulate material in the Unit 2 Turbine Lube Oil (TLO) system.
ILqsults: The inspector concluded that the foreign particulate matter was intentionally placed in the system. The identity of the responsible individual (s) was not established. The motivation or reason the material was placed in the Turbine Lube Oil system could not be determined with certainty.
The possibility of malicious intent was not conclusively disproven.
It appears likely, however, that it may have been done as the result of a poor work practice in order to stop the flow of residual turbine lube oil from the system onto the floor while the turbine lube oil cooler was disassembled for cleaning.
The licensee's initial technical and security evaluation of this incident was weak.
The poor initial handling of this matter may have contributed to the overall lack of definitive findings.
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9405230062 940517 PDR ADOCK 05000373 G
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REPORT DETAILS 1.
Key Persons Contacted In addition to the key members of the licensee's staff listed below, the inspector interviewed other employees, contractor personnel, and members i
of the-security organization. The asterisk (*) denotes those present at-the-Exit Interview conducted on April 21, 1994.
- D. Ray, Station _ Manager-l
- J. Schmaltz, Operations Manager
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- T. Newmon, Master Mechanic
- C. Sargent, Services Manager
- J. Lockwood, Regulatory Assurance Supervisor
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J. Bruciak, Maintenance Staff
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- R.
Sillon, Station Security Administrator-R. Hynes, Site Quality Verification P. Laird, Corporate Director of Security L. Lauterbach, Site Engineering and Construction
- R. Morley, Corporate Security Administrator l
B. Saunders, Corporate Security Administrator S. Techau, Assistant Station Security Administrator
- J. Otlewis, System Engineer
- H. Cybil, INP0
- D. Hills, Senior Resident Inspector
- J. Belanger, Senior Physical Security Inspector 2.
Entrance and Exit Interviews
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a.
At the beginning of the inspection, Mr. R. Dillon, Station Security Administrator was informed of the purpose of this inspection, its scope and the topical areas to be examined.
b.
The inspector conducted an exit interview with the licensee representatives denoted in Section 1, at the conclusion of the inspection activities. A general description of the scope and conduct of the inspection was provided.
Briefly listed below are the findings discussed during the exit interview. The licensee representatives were invited to provide comments on each item discussed. The details of each finding listed below are referenced, as noted, in the report.
(1)
The initial review of this incident by plant staff, as recorded in PIF-1245 appeared untimely. Although foreign material was conilrmed through analysis the day after discovery, a PIF was not written for two weeks. The final review and analysis was not approved by management until January 26, 1994.
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(2)
Corrective actions taken as a result of the initial discovery of foreign material were not effective in cleaning the equipment.
This resulted in additional clogging of the system.
(3)
The initial evaluation of potential tampering was weak.
Security staff waited for additional technical evaluation that was slow in coming.
Initial questioning of several workers involved with the TLO cooler project was limited and was of limited assistance to a security evaluation.
(4)
The second review was more comprehensive and provided significant additional information.
However, a key fact relating to the cleanup of residual oil under the-TLO cooler shell was virtually omitted.
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Event Backaround During a Unit 2 outage the "A" Turbine Lube Oil (TLO) cooler was disassembled for cleaning.
This was the first time this had been done.
The internal tube bundle (which carries water used to cool the surrounding oil) was removed and sent offsite for cleaning.
While removed, the vertical cooler cavity (approximately 4 feet in diameter and about 12 feet high) was open on top and bottom and was unmonitored for long periods. A problem with residual oil leakage from the inlet (located near the bottom) caused repeated cleanups of spilled oil under the cavity.
Prior to reassembly no specific detailed inspection was done of the inlet or outlet piping or flow pocket associated with the cooler cavity.
The system fouled about one minute after the oil flush and TLO system was started.. The flush was a standard function done to filter small amounts of foreign material that may have gotten in the oil during system disassembly.
This was the first time any foreign matter would have been discovered.
Samples were taken, analyzed, and identified as calcium-silicate and cellulose, components of a common pipe insulation.
The TLO reservoir (a 10,000 gallon tank) was drained and no foreign material found. A high velocity flush of the "AA" cooler was conducted.
Repeated cloggings were encountered and eventually the cooler was disassembled, cleaned and the reservoir refilled with reconditioned oil.
During that process flow was swapped to the "AB" cooler.
Eight days after the initial event they considered recovery completed after running the "AB" TLO cooler.
Forty-four days later they swapped back to the
"AA" cooler.
The system fouled a second time shortly thereafter.
The TLO cooler was again disassembled. They found foreign material throughout the cooler bundle, indicating that the source may have been at the oil inlet rather than the outlet.
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4.
Licensee's Investiaations Summaries Problem Identification Form 374 ^91-93-01245 While performing the standard startup fine mesh screen flush (for 20-30 seconds) on the Unit 2 TLO system on October 19, 1993, large amounts of foreign particulate matter clogged the screens.
This flush was routine and was intended to filter out small particles that may have entered the system during the maintenance outage.
On October 20, 1993, samples of the material were sent to the System Materials Analysis Department for analysis. The results, received the same day showed the material to be primarily cellulose fibers and calcium silicates (cal-sil). This material was similar to common insulation used on pipes.
The Problem Identification Form (PIF) was written on November 1,1993,
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almost two weeks after discovery.
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An initial investigation was conducted by licensee and contractor engineers, maintenance staff and General Electric management. Although informed, site security staff did not participate.
This investigation consisted of a review of the PIF, interviews with some of the engineers involved with the system and interviews with some of the craft personnel involved in the TLO cooler disassembly and cleaning project.
The conclusions reached as a result of this first investigation were completed and approved by management on January 26, 1994.
Some of the conclusions included:
The cal-sil material must have been placed in the outlet of the TLO cooler.
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TLO cooler "AA" had been removed for cleaning from September 22 to October 1, 1993.
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The system is a solid welded system from the supply discharge at-i the reservoir to the turbine so there are no possible points of entry prior to the screens.
The openings to the cooler were not inspected prior to reassembly.
It would be nearly impossible for a quantity of this material to j
haphazardly drop into the rectangular outlet openings in the cooler shell. The outlet opening in the side of the shell was within one foot of the top opening when the cooler was disassembled and easily accessible to anyone on top of the oil tank.
There was no insulating work going on in the vicinity of the TLO cooler, but laborers worked on cleaning up a significant amount of oil leaking after the tube bundle was pulled from the shell.
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Their corrective action was a high velocity flush of the. system which, PIF report 93-01245 says, " proved to be very effective in the removal of the calcium silicate." The lube oil reservoir was refilled with reconditioned oil by October 27, 1993. The Plf indicated that the only practical long term corrective action was for the maintenance staff to
" add a note regarding this event and the possible entry of foreign material to the job history."
On December 12, 1993, the screens became fouled again. A second PIF (374-200-93-01482) was written and a second investigation was conducted.
Problem Identification Form 374-200-93-01482 At about 7:00 p.m on December 12, 1993, during a routine inspection and cleaning of the TLO System return oil guillotine screen in the oil reservoir, heavy fouling was again discovered.
Resulting excessive differential pressure had caused one screen to bow. The system was.
secured on December 13, 1993, in order to clean it. The system was restarted at about 10:30 a.m. and ran until about 2:15 p.m. when the screens became heavily fouled again.
Initially, these (the October 19 and December 12 incidents) were
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considered separate, recurring events. The licensee's second investigation, however, concluded that they were each manifestations of a common event that had first become apparent on October 19, 1993.
.I New information presented in this PIF by the five person review team (composed of maintenance, operations, quality assurance and site security personnel) included:
Cal-Sil would have a tendency to sink or sit in a location until it is swept away by the oil flow.
There was no practical way to specifically identify from where it may have come. The material was common at the site.
The timing of system manipulations and changes correlate to the indicators of fouling.
During the second clean up foreign material was observed dispersed on the fins and baffle plates inside the tube bundle in the "AA" cooler bundle.
A system walkdown identified no other likely points the foreign material could be introduced.
The conclusions reached as a result of this second investigation were finalized by licensee management on January 29, 1994.
Some of their conclusions included:
There was only one event. Analysis of samples of the material found in the system each time showed them to be identical.
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The root cause of the second incident was poor corrective action for the first incident. The corrective action for the October 19th event was inadequate and allowed manifestation of the same problem in December.
The visual method of monitoring cleanup by looking at screens was not totally adequate.
No standard had been established for oil cleanliness.
Time pressures and economic considerations undoubtedly existed to complete the initial recovery work quickly.
It was most probable that a longer flush combined with longer intervals between swapping coolers would have provided indications of it, adequate cleanup.
Evidence indicated that the material originated in or near the inlet or supply side (rather than the outlet) of the TLO cooler because material was found dispersed throughout the cooler bundle (up-stream from the outlet).
An inadvertent introduction of the material into the system was improbable due to the configuration of the cooler shell.
The material could only have been placed while the cooler was
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disassembled between September 22 and October 1,1993, a period of 10 days.
The inlet, near the bottom of the cooler, was accessible.
Although the shell was inspected prior to reassembly, no emphasis was placed on the inlet and outlet pockets. Nothing was observed.
The true cause of the introduction of foreign material was inconclusive.
The two most plausible possibilities were (1) the material was placed in the system by a well intentioned individual
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to stop residual oil leakage, or (2) the material was placed in the system with unknown intent.
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NRC Evaluation No violations or deviations were identified.
i The licensee's initial evaluation to the first manifestation of this H
problem appears to have been conducted as trouble shooting for repeated clogging of the TLO screens, rather than an evaluation of potential i
tampering.
A Problem Identification Form (PIF) was written and dated November 1, 1993, 15 days after the incident. The evaluation was done
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by system engineering and included laboratory analysis of the material and interviews with seven individuals who were still available at the site.
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The results of the analysis of the material were received the day after the initial incident and demonstrated that the material was clearly foreign to the system.
The interviews of managers and foremen were conducted November 5 and 6, 23 days after the incident.
The standardized interview questions focused on providing opinions on how this could have happened and if all openings were covered.
Based on the interview records, it appeared that a simple description of multiple observations of actual work was not obtained.
Only three of six craft workers who had worked on the disassembly, oil cleanup and reassembly were interviewed. They had all left site and only three were subsequently located and interviewed.
The initial PIF contained no clear conclusion.
It did say "Since no plausible explanation was uncovered, it also appears that material'might have been placed at this point [ top outlet] in the system." There was
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no mention of who may have placed the material in the system and there was no mention of any further pointed investigation into that issue at that time.
The inspecter learned tnat four laborers were required to make repeated trips under the shell to attempt to clean up spilling oil from the inlet opening. This clean up required them to crawl under the tank (approximate 3 foot clearance) mop up oil and drag heavy, oil soaked-absorbent material back to an opening (20 feet) where it had to be lifted out and disposed.
Eventually, buckets were used to catch leaking oil.
They estimated that six, five gallon buckets of oil were arduously removed.
The Station Security Administrator (SSA) was initially notified of this about one week after the incident and was only told that a PIF would be written for their review. No details were provided had the SSA waited for additional information.
On about November 11, 1993 (23 days after the incident) the SSA, Assistant SSA and a representative of the corporate security officer were shown a draft PIF (PIF 93-01245).
Their initial evaluation of the PIF was that it was of poor quality and provided no clear indication of the potential problem. They requested additional " technical evaluation" be done in order to provide an adequate understanding of the incident upon which to base a security investigation.
Security had received no response when the "second incident" occurred about 30 days later.
The licensee's corrective actions and cleanup for the initial contamination were inadequate because shortly after restart the system's filter screen's became fouled again.
The second evaluation of this incident was more comprehensive and was conducted by a team that included experienced representatives from the maintenance, quality verification, engineering and security staffs.
The team was established by the Maintenance Superintendent.
The licensee's security staff was notified of this issue about one week after it occurred. No incisive investigation was undertaken initially because the fact pattern was somewhat unclear.
The site security staff, in conjunction with corporate security staff asked and relied on plant
staff to provide additional information. That information was slow in
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coming. Aggressive attempts to force a timely evaluation apparently did not occur.
Corporate security investigators never entered this case even though several of those interviewed indicated they believed this was done deliberately. According to corporate staff, the initial PIF evaluation was considered limited and did not contain enough facts to clearly indicate that intentional tampering had occurred. There was not enough information upon which to base an investigation.
Plant staff was requested to get additional information.
It should be noted that one very relevant fact was not specifically mentioned, except in passing as a potential explanation in the second investigation.
Several laborers were required to clean up residual oil spilling from the TLO cooler shell. That job required them to go under the oil tank (2-3 foot clearance) ani transverse a distance of about 20 feet to the area of the spilling oil (under the open cooler shell).
This was dark, dirty, smelly, heavy work that repeated.
The oil source may very well have been the inlet opening which was only about 4 feet from the floor, directly above the cleanup.
It would have been very easy for someone to stand up inside the shell and place material in the inlet to dam leaking oil. As noted in the second PIF, although an inspection was done of the shell before reassembly no specific emphasis was placed on the inlet pocket or inlet piping (the likely location of a potential " oil dam").
Plant staff indicated that work on pipes had been extensive during the outage.
Part of that work, at several locations throughout the plant, included removing insulation. This insulation may have appeared as a donut after removal. The round shape may have appeared a tailor-made dam for the leaking oil.
In summary, there were people at the location of the oil leak with an opportunity and reason to place foreign material in the TLO system.
Based on these facts it seems likely that poor work practices led to the incidents reported in the PIFs.
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