ATTACHMENT A BUILDING 50 SUBSURFACE CONTAMINATION … · cause of this contamination. Cameco also...

ATTACHMENT A

BUILDING 50 SUBSURFACE CONTAMINATION

SUMMARY REPORT

October 15, 2007

Attachment A: Summary Report Page 2 of 25 Building 50 Subsurface Contamination October 15, 2007

GLOSSARY OF TERMS AECB Atomic Energy Control Board A & E Audits and Evaluations BH50-2, etc. Borehole series wells CARs Corrective Action Recommendations CNSC Canadian Nuclear Safety Commission CTCW Cell Tempered Cooling Water Eldorado Eldorado Nuclear Ltd. ERA Environmental Risk Assessment ‘Floors, Sumps & Trenches’ Floors, Sumps, Trenches, Pits and any associated Joints Golder Golder Associates Ltd. KOH Potassium Hydroxide MOC Management of Change MOE Ontario Ministry of the Environment Monel

Monel 400 material of construction (a copper-nickel based alloy)

NI Needs Improvement NDE Non Destructive Examination N-S Trench North-South Trench PHA Process Hazard Analysis Pit Effluent Pit PM Preventive Maintenance RW Refinery Well SPAC Standard, Policy or Administrative Control Specs Specifications Study Area Effluent Treatment, Cell Room, and Cell Maintenance

Area UF4

UF6

Uranium Tetrafluoride

Uranium Hexafluoride UO2 Uranium Dioxide


TABLE OF CONTENT GLOSSARY OF TERMS................................................................................................... 2

Specifications.......................................................................................................... 2 Uranium Tetrafluoride ............................................................................................ 2

1.0 EXECUTIVE SUMMARY .................................................................................... 4 2.0 EVENT SUMMARY.............................................................................................. 5 3.0 ROOT CAUSE INVESTIGATION PROCESS ..................................................... 6 4.0 PROCESS DESCRIPTION .................................................................................... 7

4.1 Fluorine Production .................................................................................... 7 4.2 Cell Tempered Cooling Water Circulation System .................................... 7 4.3 Cell Maintenance ..................................................................................... 10 4.4 Liquid Effluent Treatment ........................................................................ 10

5.0 QUALITY ASSURANCE PROGRAM ............................................................... 11 6.0 DESIGN CHANGES TO FLOORS TRENCHES AND SUMPS........................ 12

6.1 Trenches.................................................................................................... 12 6.2 Sumps........................................................................................................ 14 6.3 Pit .............................................................................................................. 14

7.0 CONTAMINANT TYPES AND SOURCES....................................................... 16 8.0 IDENTIFICATION OF ROOT CAUSES ............................................................ 20 9.0 IDENTIFICATION OF RECOMMENDED CORRECTIVE ACTIONS............ 23 10.0 ASSESSMENT OF IMPACT............................................................................... 24 11.0 MANAGEMENT RESPONSE............................................................................. 25

Attachment A: Summary Report Page 4 of 25 Building 50 Subsurface Contamination October 15, 2007 1.0 EXECUTIVE SUMMARY

Upon identifying the potential for uranium and other chemical subsurface contamination of Building 50, Cameco shutdown the uranium hexafluoride (UF6) facility as a precautionary measure and commissioned an investigation into the cause of this contamination. Cameco also initiated a root cause investigation that was lead by a third party investigator utilizing the TapRooT® investigation process. Cameco hereby provides the results of this investigation in the TapRooT® report entitled, “Subsurface Contamination Incident Port Hope UF6 Plant (October 2007)” found in Attachment C of this submission. The attached report provides extensive details that Cameco has summarized in this report. Contaminants found in the subsurface are present in the process liquids which entered the subsurface through floors, sumps, pits, trenches and associated joints. Process fluids entered these structures either by original design or through subsequent design changes. Some of these structures were not designed to handle these liquids and few of these had any provisions for any type of preventive maintenance. The extended presence of process fluids in the structures, either by use or construction which created low points for fluid collection, combined with insufficient design (i.e. no liner), design control and monitoring of these structures led to their deterioration and eventually creation of a leak path from Building 50 to the subsurface. These structures were not originally identified as sources of potential leaks and were not identified as part of the safety related systems that were covered by the design, construction or operations quality assurance program. Although it can be shown that there was a growing awareness of the potential for the pits and sumps to leak over the years and the quality assurance program scope has since been expanded, some of these structures (i.e. floor and trenches) would still not be captured because these structures were not identified as pathways to the subsurface. The TapRooT® report identified the following root causes: 1. Some ‘floors, sumps & trenches’ are not designed to resist a corrosive

environment; 2. Liquid entering ‘floors, sumps & trenches’ is frequently corrosive and

attacks the structures; 3. Uranium and chemicals frequently enter the ‘floors, sumps & trenches’; 4. Liquid and sludge remain in the ‘floors, sumps & trenches’ for sustained

periods of time; 5. Some ‘floors, sumps & trenches’ deteriorated over time and began to leak;

and 6. The monitoring program does not detect deterioration of and/or leakage

from the ‘floors, sumps & trenches’.


TapRooT® report also developed corrective action recommendations (CARs) to address all of the six causal factors, which are summarized as follows:

a) There is a need to identify “floors, sumps & trenches” as a safety related

system because of the potential leak paths. This aspect must be reflected in the Safety Report and application of the quality assurance program. Appropriate design, construction and operating standard(s) and management change controls must be established and maintained. Some minimum requirements were identified;

b) There is a need to carry out a design related assessment of credible acute and chronic challenges to the containment and then ensure containment surfaces are appropriately designed; The designs must be developed as per an approved design standard to ensure requirements (e.g. PMs and maintenance of as-built drawings) are clearly documented, communicated and implemented;

c) There is a need to implement an effective corrective action program so that problems are routinely identified and appropriate corrective action taken; and

d) There is a need to assess the adequacy of groundwater monitoring for early leak detection and implement any necessary improvements

Cameco’s management team has reviewed the root cause investigation report and accepts its findings and CARs. Management’s response and action plan to address these findings is found in this submission as Attachment B ‘Management Response to the Root Cause Investigation Report for the Building 50 Subsurface Contamination’.

2.0 EVENT SUMMARY

On July13, 2007, Cameco identified contamination from uranium in subsurface soils beneath the floor of Building 50. More specifically, the contamination was identified during excavation for the construction of a replacement structure for the cell tempered cooling water (CTCW tank) and took the form of yellow uranium precipitate that developed on the surface of freshly poured concrete in the base of the excavation Cameco’s immediate response to the discovery of the contamination was to notify the regulatory agencies and shut down production operations in the affected areas. This was to not only eliminate the potential continued contribution of contamination, but also to facilitate an investigation into the source(s) of the contamination. On the day of the contamination discovery, Cameco retained a third party consultant and subsequently initiated drilling through the plant floor to install boreholes for sampling of the groundwater. Groundwater sampling from wells installed in these boreholes would determine if the contamination existed at greater depth and to determine if the contamination was impacting the groundwater.


Chemical analysis of the groundwater samples indicates that the contamination contained typical process chemicals and existed at depths that made it subject to possible groundwater movement. The contamination was not detected at the perimeter refinery wells, which were the installed to detect ground water contamination at the edge of the property. At this point, Cameco determined that a complete shutdown of UF6 production in Building 50 would be required to facilitate the expanded scope of the investigation. Cameco’s response to this discovery had four main components. Three of these were facilitated by Golder Associates Ltd., including a hydrogeological investigation to delineate the extent of the contamination; evaluation of the concrete structures in Building 50; and facilitation of a Process Fluid Task Force (the Task Force) to investigate operational options for handling process effluents. The fourth component was a root cause investigation led by a third-party investigator (KnoW Problem, Inc) and supported by another third-party investigator (CJB Consulting Associates Inc) in order to find the causes of the contamination and develop effective CARs. The Task Force’s mandate is to develop design criteria associated with handling of fluids. Criteria identified by the Task Force will be assessed for consistency with the root cause investigation CARs and then any conflict will be resolved. Cameco will thereafter implement any necessary additional actions to address the accepted corrective action recommendations.

3.0 ROOT CAUSE INVESTIGATION PROCESS

There were two main investigations associated with this event. The first, which was initiated immediately after Cameco identified the uranium contamination was the investigation conducted by Golder. As described earlier, this aspect of the investigation was further broken down into two sub-investigations: the physical state of the concrete structures; and a drilling program to determine the existing soil and groundwater conditions. The third component mentioned above, the Task Force activities were more related to the development of design criteria for liquid management. The second investigation was the root cause investigation and started in early August. Although the primary purpose of this summary report is to summarize the root cause investigation, these investigations overlap and this section provides a brief overview of and some context for the relationship between these different investigations. Before discussing the TapRooT® report, it is appropriate for Cameco to outline the rationale for commissioning the preparation of such a report for this incident. Cameco’s Incident Assessment Matrix governs the level of investigation that Cameco will undertake in response to an incident. For this incident, this matrix required a detailed investigation to be conducted by a team lead by a qualified


causal analyst: more specifically, for this level of event, a TapRooT® or an acceptable equivalent investigation methodology was required. Accordingly, Cameco commissioned the investigation by an independent third party. The root cause investigation team, lead by Mr. Brian Locker, the primary TapRooT ® consultant, was supported by Mr. Colin Bromley, a third party expert in corrective action processes. Mr. Locker facilitated the investigation team activities that culminated in the TapRooT ® report which is provided as Attachment C of this submission. Once the root causes were identified, Mr. Bromley facilitated the investigation team’s alignment of these root causes and the development of the CARs.

4.0 PROCESS DESCRIPTION

A schematic of the Study Area is attached (Figure 1). The Study Area involves the cell room (fluorine production, with its associated cooling water circulation system), cell maintenance and liquid effluent treatment.

4.1 Fluorine Production

Fluorine (F2) gas is produced from anhydrous hydrogen fluoride (AHF), for use in converting intermediate product uranium tetrafluoride (UF4) to UF6. This operation is carried out in the Cell Room in a series of 54 electrolytic cells. Up to 12,000 amperes of direct electric current is passed through an electrolyte consisting of potassium bifluoride (KHF2) and liquid AHF, hydrogen (H2) gas is released at the cathodes, and F2 at the anodes. The electrolytic cells are located on the ground floor of the Cell Room.

4.2 Cell Tempered Cooling Water Circulation System

Circulating water is used to cool or heat the electrolytic cells as required. The closed system consists of a below grade steel tank and three submersible pumps to direct water to a heat exchanger. This tank is located in a concrete structure with an air gap (interstice) between the vessel wall and concrete surface. Cell tempered cooling water (CTCW) is normally clean with process water (condensate from the 10 lb steam system) used for make-up. However, due to historic corrosion problems, traces of corrosion products (including nickel and copper) are present in the CTCW. The system can also become contaminated with HF if there is leakage through a failed cell-cooling coil. The acidic water will corrode the carbon steel and Monel components, resulting in leakages in the system. Overflows from the CTCW Trench are also directed to the Liquid Effluent area. As shown in Figure 1, the Cell Room trenches consist of two trenches that run in a west to east direction the full length of the Cell Room on the north and south


side of the Cell Room. These trenches pass underneath the east wall of the Cell Room and enter the Cell Maintenance area. Once past the wall these two trenches are connected by the N-S Trench. At the north end of this trench, a short section of trench connects these to the Pit. The south end of the trench extends south to a pit that holds the CTCW tank.

Attachment A: Summary Report Page 10 of 25 Building 50 Subsurface Contamination October 15, 2007 4.3 Cell Maintenance

The purpose of the Cell Maintenance operation is to provide fully reconditioned cells to the fluorine production area (Cell Room). Maintenance is performed on the cells periodically because during operation the cell efficiency gradually decreases to the point where maintenance is required. Cleaning involves electrolyte transfer, cleaning of the cell components and body, and the re-building and replacement of worn parts. Cell cleaning operations are conducted on the ground floor in the area in two separate open-top tanks, provided to neutralize and clean cell tops and cell bodies, using ‘clean’ (i.e. not contaminated with uranium), 25% potassium hydroxide (KOH) solution. ‘Dirty’ KOH is recycled to the Liquid Effluent treatment process. The sludge that remains in the baths is periodically removed and stored in drums.

4.4 Liquid Effluent Treatment

The function of the UF6 plant Liquid Effluent treatment system is primarily to treat collected wastewater and spent KOH scrubbing solutions (including fluoride captured in the scrubbers as KF) from all areas of the UF6 plant as follows: • uranium is recovered as potassium diuranate (KDU, K2U2O7) solids; • dissolved fluorides are recovered as potassium fluoride (KF); • regenerated dilute KOH is concentrated and recycled back into the

process; and • excess aqueous HF is neutralized.

The secondary purpose of the system is to decontaminate UF6 plant equipment (i.e. wash down equipment) prior to maintenance. A summary of intermittent liquid flows directed to this area includes the following: a) general - testing of safety showers, high conductivity steam condensate,

shop sinks; b) Cell Room area - taking cells apart, cell cleaning, cell tempered cooling

water heating, neutralization baths, floor washing; c) Flame Reactor area – floor washings; d) Liquid Effluent area – floor washings, draining of wash tanks, filter cloth

changes; e) Tower – floor washings, process area sinks; f) HF tank farm – runoff from railcar snow melt; and g) Wet and dry labs – lab sinks.


In the original design, fluorides recovery was achieved by using lime to precipitate out calcium fluoride, which was then sent off-site for recovery. Following the closure of the recovery facilities that utilised the calcium fluoride by-product in 1996, the process was modified to eliminate the use of lime for fluoride recovery. In the modified system, uranium and fluorides are removed in spent KOH as a dry flake/powder KF product and solid KDU. Any regenerated KOH is then concentrated by evaporation to maintain a plant water balance and recycled as a concentrated KOH solution for re-use in the scrubber system. The evaporator vapours are condensed and recycled to steam production following conductivity checks.

5.0 QUALITY ASSURANCE PROGRAM

The operation of the UF6 plant was and continues to be subject to a quality assurance program that was focused on safety related equipment and systems. This was documented in the Quality Assurance Manual Plant Operations as follows:

“The quality assurance programme shall apply to the following systems:

i) pressurized fluorine; ii) anhydrous hydrogen fluoride (liquid); iii) uranium hexafluoride (liquid); iv) anhydrous ammonia (liquid); v) hydrogen; vi) emission control equipment – gaseous and liquid; and vii) other systems as required.

The specific equipment that is affected by this programme is termed safety related equipment and is listed in Appendix A.” The most logical alignment of the floor trenches and sump structures in terms of being one of the safety related systems would be as part of an emissions control system. However, the emissions-based safety system focused on equipment dealing with actual emissions to the air and water. As floor trenches and sumps were not intended to involve discharge, they were not judged to be part of the emissions control safety system. Therefore the Pit, trenches, sumps and floors that are described in this report would not be handled under the requirements of the operations quality assurance program between 1984 – 2005. In January 2006, the quality assurance program was expanded to all licensed activities. Since that time, all design changes would be processed in accordance with the design change procedures.

Attachment A: Summary Report Page 12 of 25 Building 50 Subsurface Contamination October 15, 2007 6.0 DESIGN CHANGES TO FLOORS TRENCHES AND SUMPS

The TapRooT® investigation report has defined “floors, sumps & trenches” as “floors, sumps, trenches, pits and any associated joints”. This definition will also be used in this report. The “floors, sumps & trenches”, as they existed at the time of the original plant construction for the Study Area were the trenches, sumps and Effluent Pit. Trenches were built in the floors of the Cell Room, Cell Maintenance and Liquid Effluent area. Sumps were built in the Liquid Effluent area, which contained four (4) below-grade sumps and the Effluent Pit. The Effluent Pit was an open topped below grade structure. For consistency with the TapRooT® report, the Effluent Pit will be referred to as the Pit. Only the Liquid Effluent sumps were given equipment numbers, whereas the Pit and trenches were simply part of the Building 50 structures. As indicated above, none of these structures were identified as being part of a designated safety related system, so the design, construction and operations quality assurance program did not apply. In addition, the site Safety Report did not identify leaks through concrete floors and trenches as a potential leak path to the subsurface.

More detailed information on these is provided below.

6.1 Trenches

There are several trenches located on the ground floor of Building 50. They are identified in the original design drawings and although some are lined, generally, their design intent was not documented. The Study Area had three such trench systems, the Cell Room, Liquid Effluent and Cell Maintenance trenches. Both the Liquid Effluent and Cell Maintenance trenches were lined, but the Cell Room trenches were not. In addition, those areas with lined trenches also had coated floors. The coated floors and lined trenches suggest that some process liquids of a potential corrosive nature would be expected. These trenches and their relative location to each other and the Pit are shown in Figure 1. It should be noted that, the original drawings indicated that only the Cell Room trenches and Cell Maintenance trenches were connected via the Pit. As shown in Figure 1, the Cell Room trenches consist of two trenches that run in a west to east direction the full length of the Cell Room on the north and south side of the Cell Room. These trenches pass underneath the east wall of the Cell Room and enter the Cell Maintenance area. Once past the wall these two trenches are connected by the N-S Trench. At the north end of this trench, a short section of trench connects these to the Pit. The south end of the trench extends south to a pit that holds the CTCW tank.


There is very little mentioned about these trenches in the original Lummus Engineering Design Manual for Building 50. It is also worthwhile noting that in the evolution of Eldorado’s and Cameco’s thinking related to in-ground structures, the focus has been on sumps and pits. Further, there is nothing provided in the design manuals that would have assisted the operations in assessing trench related design changes. The Cell Room trenches were not lined and liquids were not routinely expected in them. It was understood that these trenches were primarily to house the tempered cooling water return line from the cells and convey any water that might be present away from the cells. Water entry into these trenches might occur in one of two ways. If molten electrolyte is discharged from a cell, due to over-pressurization, the electrolyte quickly freezes and is scraped up and shoveled into a drum. Water may be used to wash down the spill area and it is directed to the trenches. The other water source is leakage from the cell tempered cooling water piping components. Water leakage at piping components typically occurs at the threaded connection of the piping from a cell into the common return line. The acidic nature of the electrolytic cell operation results in the corrosion of Monel components (liners and cooling coils). In the event of wear through of a cooling coil, the tempered cooling water will become contaminated with electrolyte. Electrolyte itself becomes contaminated with the chemicals that it is exposed to and includes concentrations of arsenic (from the AHF) and nickel and copper (from the Monel cell components). There would be little or no uranium expected in the electrolyte. The electrolyte contains HF, which would make the water acidic. Any water in the Cell Room trenches should have flowed from the west end to the east end and then into the common N-S Trench and ultimately into the Pit. Actual elevation measurements indicates the slope is minimal and there are low points in some sections. The Liquid Effluent trenches would contain the scrubber solutions, which are primarily KOH of varying strength along with uranium, fluoride, and smaller concentrations of arsenic. These solutions are generally caustic and the floors and trenches were coated to handle them. Cell Maintenance floors and trenches were intended to handle the neutralized electrolyte and therefore would contain KOH, arsenic, copper, and nickel and lower concentrations of uranium. The uranium would have been present in the KOH scrub solution as the solution was recycled, which is to say that the solution was treated and reused. At present, recycled KOH is not used which should eliminate the uranium from this source.


The shallow trenches connecting the Effluent Room trenches to the N-S Trench are not part of the original construction and appear to have been installed prior to 1986.

6.2 Sumps

Sumps installed in the UF6 plant had a steel liner with a gap between it and the concrete structure. Although the design manual makes no mention of this, this design was, to the best of our knowledge, developed based on operating experience. The Lummus Engineering Design Manual describes the acid wash (small items), rinse tank and caustic wash tanks along with the four (4) sumps for the Liquid Effluent area. Two sumps were intended to collect overflows and tank drainage. The other two collected wash solutions and other overflows. The estimated flows for these discharges were described in the Lummus Design Manual as follows: “The above flows are best guessed estimates by ENL and LCI. The flows listed are small and infrequent enough that the 405 Area (Sump Treatment) will have no problem handling this extra wastewater.” Two of the metal-lined sumps are still in operation. In 2000, one sump was converted to a shallow pump box, while the other sump was filled-in. No specific preventive maintenance program was established to perform the monitoring on these sumps. The area engineer conducted an inspection, which led to filing of a sump as previously described.

6.3 Pit

The structure that is presently referred to as the Pit was originally simply an in-ground structure. It has no equipment identification number so there is little information other than what is provided in the structural drawings. The Pit was not part of the Liquid Effluent system originally, but was instead part of the Cell Maintenance system. It is a lined structure and originally housed two tanks, a pump, a sump and a sump pump that was to be supplied as needed. These are detailed in Process & Instrumentation Drawing (P&ID) 302005 Sheet 1. The trenches also flowed into this Pit. A reference to the Pit in the Lummus Engineering Design Manual identifies this as a sludge pit. It contained two neutralization tanks, one which received the sludge from the cell cleaning operation and overflowed to the second. The pit also received floor drains from the area. The contents of the tanks were pumped to the Liquid Effluent circuit.


From discussions with various personnel interviewed it is understood that the two tanks did not operate as designed. The sludge that was discharged into the tanks from the Cell Maintenance area proved more difficult to handle and required manual cleaning. It is also important to note that the actual cell life was initially about 50% of the anticipated design life, resulting in more sludge than anticipated. Their placement in an in-ground structure added to the workload. In response to these difficulties, an engineering project was created to remove the two tanks, pump, and associated piping/wiring; modify the piping and install submersible pump; connect the fume line vent; and, install a cover plate. The project request was created on December 19, 1984 and the completed project signed off in the fall of 1986. A review of the engineering project file identifies one key aspect of the project, in that the function of the Pit would be changed from secondary containment to primary containment. The client notes that the pit “was designed for secondary containment with the tanks as primary containment. We should, if at all possible, retain this concept. If it is impractical to do this then we must take a calculated risk that when the dykes develops a leak we can correct or control it.” The project engineer notes, “the pit would now be used for primary containment when it was initially designed for secondary containment with short term liquid holding requirements”. He goes on to say, “Unless the concrete has been effectively coated and sealed, leaks will almost certainly develop and could prove difficult to detect and repair.” It was recommended that the pit be re-sealed with an appropriate material. There is no evidence that the pit was re-sealed, the lining is as originally installed. The Golder inspection of the pit did not identify any leak paths. Additional analysis would suggest that although it is secondary containment in the context of the two tanks, it is in fact primary containment in the context of this area of Building 50. Any water that is released into this area of the building will eventually enter the Pit, as it is a low point in this section of Building 50. It may help to explain why the Pit, as secondary containment, was in fact lined. This reality, though not formally documented, became evident during the times when the plant experienced water balance problems. These occurrences were often enough in the first few years that it became an accepted practice to use this structure in this manner and it thereafter became an integral part of the effluent circuit. As early as December of 1984, this in-ground structure is referred to as the effluent Pit. The water balance problems required provision of additional tankage, which took the form of a 10,000 gal vessel, which was relocated to the plant and was in use until late 1987. In summary, the changes that were made to the trenches in the Liquid Effluent area (creation of shallow trenches), and the constant presence (poor slope and/or low points) of liquids in this area, lead to the Cell Room trenches being exposed to more liquids that had been anticipated. These trenches were not lined, and the


additional design construction (floor to wall joint and lack of slope), meant that the corrosive effluent would enter and be retained in the trenches. This eventually led to the leak path identified by Golder. The modifications in the Liquid Effluent area also damaged the coating on the floors, which were intended to receive these liquids and were designed for it. The concrete floor then developed additional leak paths as determined by Golder. Although the above discussion focuses on sumps, pits and trenches, there are many other forms of in-ground structures. As a final comment on in-ground structures, the “floors, sumps & trenches” have a finite service life. Although not explicitly stated it has become clear that the floors are barriers between the subsurface and process fluids and as such they must be periodically inspected and maintained to ensure their integrity. This aspect of their function has not been identified previously.

7.0 CONTAMINANT TYPES AND SOURCES

Contaminant sources were identified as potentially coming from any of the following areas:

a) historical pre-existing conditions of the current UF6 plant; b) migration from off-site waste contaminated soils; c) deposition of licensed emissions around the facility; d) spills or other operational activities; and e) leakage of contaminants from within Building 50.

The area around Building 50 is part of the historical contamination associated with the operation of the original refinery operations, which were shutdown in the early 1980s. These included a waste site located to the north and west of Building 50 and the surrounding soils that were contaminated from historical emissions (i.e. deposition from air emissions, spills, etc). Soil underneath and adjacent to Building 50 was removed when the plant was constructed and the replacement soil should not have been contaminated. The exact depth and quantities of soil were not established in this investigation. Re-contamination of the clean soil could only then occur from contaminant migration from the soil below it which had not been removed; emissions or spills from the current operation; or leakage from Building 50 itself. The complex nature of current and historic emissions requires careful examination of the data. For example, the presence of arsenic as a hexafluoroarsenate (the form of arsenic which was introduced to the UF6 plant as a contaminant in the purchase HF) is associated with the current operations, any speciation of the arsenic would likely imply a historical source. The presence of the hexafluoroarsenate eliminates (a) and (b). The fact that the existing groundwater monitoring wells have not detected this contamination would also eliminate (c). Spills or leaks would be very local and unlikely to have originated from the Study Area, thus focusing attention on (e).


Recent Golder sampling results from monitoring wells closer to the perimeter fence have identified contamination that has different characteristics than that of the Study Area. This suggests that contribution from (a) – (d) on the south side of Building 50 may need to be re-examined.

As discussed above, the Cell Room trench contaminants would be acidic in nature and would be expected to contain contaminants such as arsenic, copper and nickel at elevated concentrations. The Cell Maintenance area trench would contain the same contaminants as the Cell Room trench as well as KOH, and low levels of uranium. Liquid Effluent areas would contain KOH, more elevated levels of uranium and lower levels of arsenic, nickel and copper. Unfortunately, these contaminant signatures have been lost as a result of the operating conditions that have existed over the years. The water balance problems experienced during the first few years of operation resulted in the Pit being flooded, which then flooded the Cell Room trenches, mixing up the Cell Room and Cell Maintenance contaminants. Some of the flooding in the Liquid Effluent area went toward the Cell Maintenance area meaning that it would also have potentially filled the Cell Room trenches. Eventually, the Liquid Effluent trenches were connected to the Cell Room trenches with a shallow trench for a period of time. The result is that Liquid Effluents become mixed and their signatures are lost. Additionally, it was common practice to empty and wash out the floor sweepers in the Cell Maintenance trenches. This would be a source of uranium for the Cell Room trenches, regardless of the interplay with the other area trenches. The uranium level in the annular space between the tempered cooling water tank and concrete was analyzed at 5.1 % uranium. At this concentrations the only possible sources are the Liquid Effluent area solutions or the practice of dumping/cleaning of the floor sweepers. Over the last few years flooding has not been a problem and the shallow trenches in the Liquid Effluent area have been filled in. The lower levels of uranium currently found in the Cell Room trenches, may be residual uranium from past practices or from the continued dumping of floor sweeper contents. The reason for presence of residual uranium is that although the Cell Room trenches may have been shoveled out in the past, they were not likely spray washed. The presence of the irregular concrete surfaces would means some of the solids would remain after shoveling. The arsenic contamination requires some comment with respect to toxicity. Although arsenic is recognized as a toxic substance, the arsenic species from the UF6 operation is a hexafluoroarsenate and is considerably less toxic due to its low bioavailablity. The arsenic results reported by Golder are as total arsenic, and more than 95 % of it is in the form of hexafluoroarsenate. This issue has been discussed in the past with both the federal and provincial regulators. In order to


confirm that this is the situation, some of the samples were re-analyzed using different techniques and the results are presented in Table 1 below. Figure 2 identifies all of the groundwater monitoring wells that have been currently installed in and around Building 50. Proposed installations are also shown.

Table 1: Arsenic Speciation Results for Borehole Locations

Arsenic Content and Species (mg/L) ** Bore Hole Number * Total Non-

hexafluoroarsenate Hexafluoroarsenate

Percentage as Hexafluoroarsenate (%)

50-2 17 1.6 15.4 90.5950-2 17 1.6 15.4 90.5950-4 87 0.06 86.94 99.9350-2 14 1.6 12.4 88.5750-4 69 0.12 68.88 99.8350-5 52 0.033 51.967 99.94

50-10 0.245 <0.005 0.245 100.0050-15 20.6 <0.005 20.6 100.0050-8A 0.375 <0.005 0.375 100.0050-4 66 0.07 65.93 99.8950-1 45 0.06 44.94 99.8750-9 61 0.02 60.98 99.97

Average: 97.43 mg/L * Refer to Figure 2 for bore hole locations. ** mg/L = ppm

Attachment A: Summary Report Page 20 of 25 Building 50 Subsurface Contamination October 15, 2007 8.0 IDENTIFICATION OF ROOT CAUSES

The investigation was conducted using the TapRooT® root cause analysis process. As described in Attachment C of this submission, this process identifies what happened in the time leading up to and including: • The confirmation of subsurface contamination in Building 50; • The issues or problems identified in the design, maintenance and/or

routine operation of the UF6 plant; and • A determination of why these conditions existed and how they led to the

subsurface contamination. This analysis leads to the development of CARs that address the root cause of these problems. After reviewing the information gathered and summarized in the SnapChart ® found in the root cause investigation report (Attachment C), the root cause investigation identified six Causal Factors. Causal Factors are critical issues or problems that contributed to the event and all must have existed for uranium and chemicals to be discovered in the excavation for the new CTCW tank, and subsurface contamination to be subsequently confirmed. The six Causal Factors identified in this investigation, provided in chronological order are as follows: 1. Some ‘floors, sumps & trenches’ are not designed to resist a corrosive

environment; 2. Liquid entering ‘floors, sumps & trenches’ is frequently corrosive and

attacks the structures; 3. Uranium and chemicals frequently enter the ‘floors, sumps & trenches’; 4. Liquid and sludge remain in the ‘floors, sumps & trenches’ for sustained

periods of time; 5. Some ‘floors, sumps & trenches’ deteriorated over time and began to leak;

and 6. The monitoring program does not detect deterioration of and/or leakage

from the ‘floors, sumps & trenches’. Each of these Causal Factors were associated with numerous conditions as shown in the SnapChart® in Attachment C. The additional information provided by these conditions explains why the Causal Factor existed. Typically, for each of the Causal Factors, there are several root causes that detail why the Causal Factor was allowed to exist. Each of the Causal Factors were independently analyzed for root causes using the TapRooT® Root Cause Tree. The investigation into the subsurface contamination in Building 50 found root causes to be primarily grouped into the basic cause categories of Management System and Equipment Difficulty. The root cause “No SPAC” (Standards, Policies and Administrative Controls) was identified for each of the Causal


Factors (Table 2). Inadequate design specifications, problems not anticipated, lack of preventative maintenance (PM) and inadequate evaluation/hazard analysis are other common root cause themes.

Table 2. Root Causes grouped by Causal Factor

Causal Factor Basic Cause Categories

Near Root Cause Categories Root Causes

Management System

Standards, Policies or Admin Controls (SPAC) NI

No SPAC

Confusing or Incomplete

Drawings/prints NI

Design

Design Specs NI

Equipment environment not considered

Management of Change (MOC) NI

Hazard analysis NI

Some ‘floors, sumps & trenches’ are not designed to resist a corrosive environment Equipment

Difficulty

Preventive/Predictive Maintenance

No PM for Equipment


No SPAC

Confusing or Incomplete Management

System Oversight/Employee Relations A&E lack depth

Procedures Not Used/Not Followed No procedure

Liquid entering ‘floors, sumps & trenches’ is frequently corrosive and attacks the structures

Equipment Difficulty Design Problem not

anticipated Standards, Policies or Admin Controls (SPAC) NI

No SPAC Uranium and chemicals frequently enter the ‘floors, sumps & trenches’

Management System Oversight/Employee

Relations

Employee feedback NI

Employee communications NI

Attachment A: Summary Report Page 22 of 25 Building 50 Subsurface Contamination October 15, 2007 Table 2. Root Causes grouped by Causal Factor



Equipment Difficulty Design Problem not

anticipated


No SPAC Management System

Oversight/Employee Relations A&E lack depth

Equipment Difficulty Design

Design Specs NI

Problem not anticipated


No SPAC Management System

Corrective Action Corrective Action NI

Design

Design Specs NI

Equipment environment not considered

Management of change (MOC) NI

Some ‘floors, sumps & trenches’ deteriorated over time and began to leak Equipment

Difficulty

Preventive/Predictive Maintenance

No PM for Equipment

PM for Equipment NI

Attachment A: Summary Report Page 23 of 25 Building 50 Subsurface Contamination October 15, 2007 Table 2. Root Causes grouped by Causal Factor




No SPAC Management

System Oversight/Employee Relations A&E lack depth The monitoring

program does not detect deterioration of and/or leakage from the ‘floors, sumps & trenches’ Equipment

Difficulty Design

Design Specs NI

Problem not anticipated

Management of change (MOC) NI

Hazard analysis NI

The challenge once the root causes are determined is to present them in a format that is succinct and manageable. The common theme found in this investigation was that right from the design stage of Building 50, the Liquid Effluent area was not considered part of the building’s formally identified safety systems, and the floors and trenches were not identified as potential leak paths. Over time there was a growing awareness of the sumps and the Pit as potential leak paths, but there was no formal recognition of this potential issue. As such, policies regarding the integrity of these structures were limited, hazard analysis programs did not flag these areas as critical, and PM programs were not triggered.

9.0 IDENTIFICATION OF RECOMMENDED CORRECTIVE ACTIONS

Thirty-four root causes were determined through the analysis of the six Causal Factors through the TapRooT® process. Following the root cause analysis, each root cause and the analysis pathway that lead to that root cause was reviewed. The root causes were then grouped by similar themes and four groups of related root causes emerged. Then, for each group of root causes, consideration was given to what would have been the activities and circumstances that could have prevented each root cause in the group from being selected. These activities and circumstances were then combined to form a corrective action recommendation (CAR). These CARs are outlined below, the recommendations with the associated root causes are provided as part of the root cause analysis report in Attachment C of this submission. Corrective Action Recommendation 1 - Cameco Port Hope needs to identify “floors, sumps & trenches” as a safety related system because of the potential for leak paths. This aspect must be reflected in the Safety Report and in the application of the quality assurance program. Appropriate design, construction


and operating standard(s) and management change controls must be established and maintained. As a minimum, these must ensure that: a) “floors, sumps & trenches” have corrosion resistant surfaces where

appropriate; b) “floors, sumps & trenches” have double barriers, and monitoring between

barriers for any chronically wet locations such as sumps or pits; c) any spills to “floors, sumps & trenches” are promptly cleaned and/or

neutralized; d) “floors, sumps & trenches”, and associated monitoring systems, are

appropriately inspected and maintained; and e) procedures are written and implemented to ensure that no contaminated or

corrosive liquids are deliberately discharged to “floors, sumps & trenches” except where they have a corrosion resistant liner.

Corrective Action Recommendation 2: Cameco Port Hope needs to carry out a design related assessment of credible acute and chronic challenges to ‘floors, sumps & trenches’ and then ensure their structural surfaces are appropriately designed; The designs must be developed as per an approved design standard to ensure requirements (e.g. PMs and maintenance of as-built drawings) are clearly documented, communicated and implemented. Corrective Action Recommendation 3: Cameco Port Hope needs to implement an effective corrective action program so that problems are routinely identified and appropriate corrective action taken Corrective Action Recommendation 4: Cameco Port Hope needs to assess the adequacy of the groundwater monitoring program for early leak detection, and implement any necessary improvements

10.0 ASSESSMENT OF IMPACT

The possibility of groundwater contamination from the UF6 plant was identified at the time of the siting and construction approvals. Issues raised by the Inter-Agency Review Committee were related to the potential impact on the municipal water storage tanks, which were located to the south of the proposed facility. The assessments conducted at that time indicated that the groundwater flow was predominately to the southeast and the soil conditions were such that the groundwater flow was very slow. The assessment at the time was that should a leak occur the likelihood of impacting the water storage tanks was low and there would be sufficient time to develop and implement appropriate corrective actions. In the present situation, the municipality has relocated the water treatment facility to the west of its former location (in 2005), and the underground drinking water reservoirs south of Building 50 are no longer in use.


Although no contaminated groundwater has reached the existing Refinery Wells, the water quality results from a recently installed monitoring well, along the fenceline to the south of Building 50, has indicated uranium concentrations in the few mg/L range. Efforts are ongoing to characterize the contaminant source and southern extent of impact. It should be noted that the new findings may not be related to this investigation as the groundwater in this area is relatively low in arsenic and has near-neutral pH (whereas the groundwater impacts in the Cell Maintenance and Effluent Room area are generally high in arsenic as well as uranium, and have an elevated pH). This would suggest that the contamination may be historical.

11.0 MANAGEMENT RESPONSE

The above CARs do not identify specify actions to be taken, but rather what these actions must address. The management groups at the Port Hope conversion facility, the Fuel Services Division and the corporate office have reviewed and responded to the root cause investigation findings. Management’s response and action plan is found in Attachment B of this submission. Preventive actions, consideration of similar potential problems have also been captured in the management response.

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ATTACHMENT A BUILDING 50 SUBSURFACE CONTAMINATION … · cause of this contamination. Cameco also...

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