IR 05000346/2023050
| ML23214A344 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 08/03/2023 |
| From: | Jason Kozal NRC/RGN-III/DORS |
| To: | Tony Brown Energy Harbor Nuclear Corp |
| References | |
| IR 2023050 | |
| Download: ML23214A344 (1) | |
Text
SUBJECT:
DAVIS-BESSE NUCLEAR POWER STATION - SPECIAL INSPECTION REPORT 05000346/2023050
Dear Terry Brown:
On March 23, 2023, the U.S. Nuclear Regulatory Commission (NRC) completed its initial assessment of ground settling, which was identified as the likely cause of a firewater line break resulting in the loss of fire protection function for about 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> at Davis-Besse Nuclear Power Station on October 9, 2022. This assessment was initiated after NRC inspectors discovered information regarding numerous ground settling indications around the plant on February 27, 2023, while reviewing the firewater pipe failure. Based on this initial assessment, the NRC sent a Special Inspection Team (SIT) to your site on April 23, 2023, to assess the stations current performance in understanding ground settling occurring at the site and its potential effect on risk-important structures, systems, and components (SSCs).
On June 23, 2023, the NRC completed its special inspection and discussed the results with you and other members of your staff. The results of this inspection are documented in the enclosed report. In summary, the special inspection found that Davis-Besse Nuclear Power Station has documented well over 100 corrective action documents related to ground settlement since initial construction in the 1970s. Despite of the number of ground settling zones around the site, including notable examples, such as settlement of the cooling tower and turbine building portions, as well as recent adverse impacts to the firewater system, the station has not concluded ground settling is a site-wide issue warranting a comprehensive review.
Importantly, the special inspection did not identify any immediate safety concerns to risk-important SSCs.
Two findings of very low safety significance (Green) are documented in this report. One of these findings involved a violation of NRC requirements, as the station failed to evaluate the effects of ground settling on nearby safety-related structures not anchored to bedrock in accordance with the applicable station procedure. We are treating this violation as a non-cited violation (NCV)
consistent with Section 2.3.2 of the Enforcement Policy.
August 3, 2023 The second issue involves the stations failure to address an adverse condition on a portion of the firewater system piping. Station personnel noted a downward deflection and inadequate support in the fire protection system piping and documented a possible correlation with ground settlement. However, they did not evaluate the potential effects of this condition, as required by the stations Corrective Action Program. This condition led to the firewater line break, causing the loss of fire protection function for about 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> on October 9, 2022.
If you contest the violation or the significance or severity of the violation documented in this inspection report, you should provide a response within 30 days of the date of this inspection report, with the basis for your denial, to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region III; the Director, Office of Enforcement; and the NRC Resident Inspector at Davis-Besse Nuclear Power Station.
If you disagree with a cross-cutting aspect assignment or a finding not associated with a regulatory requirement in this report, you should provide a response within 30 days of the date of this inspection report, with the basis for your disagreement, to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region III; and the NRC Resident Inspector at Davis-Besse Nuclear Power Station.
This letter, its enclosure, and your response (if any) will be made available for public inspection and copying at http://www.nrc.gov/reading-rm/adams.html and at the NRC Public Document Room in accordance with Title 10 of the Code of Federal Regulations 2.390, Public Inspections, Exemptions, Requests for Withholding.
Sincerely, Jason W. Kozal, Deputy Director Region III Division of Operating Reactor Safety Docket No. 05000346 License No. NPF-3
Enclosure:
As stated
Inspection Report
Docket Number:
05000346
License Number:
Report Number:
Enterprise Identifier:
I-2023-050-0000
Licensee:
Energy Harbor Nuclear Corp.
Facility:
Davis-Besse Nuclear Power Station
Location:
Oak Harbor, OH
Inspection Dates:
April 23, 2023 to June 23, 2023
Inspectors:
L. Bauer, Geologist
M. Domke, Reactor Inspector
T. Hartman, Senior Project Engineer
W. Wang, Senior Geotechnical Engineer
T. Weaver, Seismologist/Geophysicist
Approved By:
Néstor J. Féliz Adorno, Chief
Engineering and Reactor Projects Branch
Division of Operating Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a special inspection at Davis-Besse Nuclear Power Station, in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information.
List of Findings and Violations
Failure to Address External Bending Loads on the Firewater System Due to Ground Settling Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green FIN 05000346/2023050-01 Open/Closed
[P.1] -
Identification 93812 The team identified a finding of very low safety significance (Green) for the licensees failure to address an adverse condition (i.e., external bending loads) on a portion of the firewater system piping. Specifically, on August 10, 2021, the licensee noted a portion of fire protection system piping was deflected downward and no longer supported properly. They considered ground settlement as a likely cause. However, they did not evaluate the potential effects of the condition as required by procedure NOP-LP-2001, Corrective Action Program.
Failure to Evaluate Ground Depressions Identified within 15 Feet of Safety-Related Structures Not Bearing in Bedrock Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000346/2023050-02 Open/Closed
[H.1] -
Resources 93812 The team identified a finding of very low safety significance (Green) and an associated Non-Cited Violation of 10 CFR 50, Appendix B, Criterion V, "Instructions, Procedures and Drawings," when the licensee failed to evaluate the effects of ground settling on safety-related structures in accordance with procedure EN-DP-01511, Structures Monitoring. Specifically, the licensee failed to perform evaluations of five areas with ground settling identified within 15 feet of safety-related structures not bearing on bedrock as required by procedure step 6.3.8.
Additional Tracking Items
None.
INSPECTION SCOPES
Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in effect at the beginning of the inspection unless otherwise noted. Currently approved IPs with their attached revision histories are located on the public website at http://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/index.html. Samples were declared complete when the IP requirements most appropriate to the inspection activity were met consistent with Inspection Manual Chapter (IMC) 2515, Light-Water Reactor Inspection Program - Operations Phase. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.
OTHER ACTIVITIES
- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL 93812 - Special Inspection In accordance with the SIT Charter (ML23129A606), the inspection team conducted a detailed review of the ground settling that has been occurring since the sites original construction. As detailed in the SIT Charter, the following items were reviewed:
the construction phase of the Davis-Besse Nuclear Power Station. The objective is to provide a comprehensive understanding of the ground settling activity at the site, its effect to risk-important structures, systems, and components (SSCs), and the licensees actions taken associated with ground settling.
2. Review the licensees evaluations of the ground settling occurrences and their potential
impact to risk-important SSCs. This includes reviewing ongoing and planned monitoring and mitigation activities.
3. Review the reasonableness of the licensees corrective action program (CAP) at
addressing internal and external operating experiences involving ground settling, including determining how the licensee considered any relevant plant-specific operating experience related to ground settling in support of their License Renewal Application.
INSPECTION RESULTS
Assessment 93812 Charter Item 1 - Establish a historical sequence of events related to ground settling occurrences since the construction phase of the Davis-Besse Nuclear Power Station.
The objective is to provide a comprehensive understanding of the ground settling activity at the site, its effect to risk-important SSCs, and the licensees actions taken associated with ground settling.
During the construction phase in the 1970s, geotechnical investigations revealed the presence of small solution cavities in the explored bedrock. Aerial analysis of the site further identified small surface depressions.
Surface depressions have been documented in the licensee's CAP since the site's construction. The licensee has attributed most of these depressions to leaking pipes. Prior to 2002, the licensees records indicate at least 16 instances of underground leaks or ground settling. These leaks involved systems such as fire protection, diesel oil, domestic water, and sanitary and storm sewers.
Since 2002, enhancements have been made to the CAP database, allowing for a more comprehensive and detailed timeline. The CAP has documented well over 100 corrective action documents related to ground settlement since 2002. Notably, on October 9, 2022, a firewater line break occurred, resulting in the loss of fire protection function for about 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. Subsequent evaluations determined that the likely cause of the pipe break was external stresses caused by ground settling.
The following detailed timeline provides relevant themed chronologies and is not intended to cover all aspects of the topic. An example of ground settling not discussed in detail in this report is the approximately 3-inch settlement of the non-safety-related Low-Level Radiological Waste Building, which is adjacent to the safety-related Auxiliary Building and not directly bearing on bedrock. The team verified that, as of the time of this inspection, it did not adversely impact the Auxiliary Building.
Bedrock During the construction phase in the 1970s, geotechnical investigations encountered small solution cavities throughout the bedrock that was explored. The reports highlighted the potential for groundwater to dissolve additional gypsum if it flowed through the bedrock. As a result of solution activity, the soluble material within the Tymochtee formation dissolved, leading to the collapse of the overlying, more resistant dolomite. Aerial analysis of the site area identified small surface depressions, which were interpreted by geotechnical investigators as being related to solution cavity activity. These depressions represented surface bedrock cavities where the overlying soils had slumped.
The Bedrock Verification Program and associated boring program conducted during construction showed no zones of low drill times or sudden drops of the drill steel. Additionally, there was also no evidence of significant solution activity observed in rock cores recovered.
However, during geologic mapping for foundation excavation, solution activity was observed at the upper 3 feet of the bedrock near the cooling tower area. To address the bedrock dissolution, a remedial grouting program was implemented.
Turbine Building Turbine building loads are supported on pier footings with diameter or maximum rectangular dimension ranging from 3 feet to 14 feet. Piers are socketed from 3 feet to 8 feet into bedrock. The piers are designed to resist maximum axial loads and moments resulting from combined static and dynamic loads. A portion of the building at ground level is not supported by piers on bedrock and is referred to as the "slab." There are no safety-related SSCs located on the slab, but it does support SSCs important to safety, such as, motor control center (MCC) E31A, a fire protection deluge pit, and the isophase bus duct cooler. Additionally, a safety-related electrical ductwork routes under the turbine building slab, which supply power to safety-related service water pumps.
2002 - The licensee identified an underground fuel oil break outside the turbine building rollup door near the auxiliary transformer resulting in significant ground settlement and excavation of the area.
2005 - The licensee identified an underground firewater main break outside the turbine building rollup door near the auxiliary transformer. The licensee determined wet backfill used during the 2002 repairs likely contributed to this break.
2013 - In June, the licensee discovered the east condenser pit sump pumps were partially clogged with debris, indicating potential washout from beneath the floor slab. In July, the licensee documented a ground depression increasing in size outside of a door on the northern wall of the turbine building. It was found that a leaning drain catch basin had caused deterioration of the basin structure. The licensee believes the 2002 backfill and excavation activities contributed to this underground drain piping failure.
2015 - In April, the licensee documented a continued increase in ground depression size in the same area as July 2013. The licensee observed washout from underneath a nearby sidewalk.
2015-2016 - The licensee estimated that an auxiliary boiler drain failure occurred between 2015 and 2016 under the turbine building concrete slab. The licensee believes the 2002 backfill and excavation activities contributed to this failure.
2016 - In March, the licensee recorded voiding under the northern turbine building, causing the settlement of an isolated phase electrical bus duct cooling unit by approximately 3 inches.
The licensee also documented separation of conduit for motor control center, E31A, as a result from turbine building slab settlement. In April, the licensee identified a strong fuel oil smell around the auxiliary 11 transformer, which is just outside the turbine building, and inside the turbine building at the fire protection deluge pit indicating a possible fuel oil leak. In July, the licensee documented continued increase in size of the ground depression immediately north of the turbine building, like the observations made in July 2013 and April 2015. In December, the licensee completed corrective actions to mitigate further settlement of the turbine building floor slab. This involved the injection of 96 cubic yards of flowable fill under the turbine building floor slab between November 8 and December 2.
2017 - In February, the licensee replaced the sidewalk outside the northern end of the turbine building after injecting flowable fill. The licensee believes that these sidewalk replacement efforts and heavy construction equipment may have applied downward forces on buried piping in this area, which could have contributed to later piping failures.
2018 - In January, the licensee observed that the flowable fill material injected in 2016 was not effective, as a borescope found a larger void beneath the floor. In March, during refueling outage 1R20, operators observed steam rising through the expansion joints in the turbine building slab when operating the auxiliary boiler. The licensee also documented further turbine building slab settlement. In April, a gap was discovered in the drain line piping of the fire protection deluge pit on the inside wall of the turbine building. Subsequent investigation revealed a 12-inch-high void extending in all directions from this drain gap.
Furthermore, the licensee detected the presence of diesel fuel oil beneath a core bore in the northern turbine building concrete floor slab. In May, the licensee poured 45 cubic yards of flowable fill into floor drains and core drills in the turbine building slab to stabilize the settlement of the flooring. The total amount of flowable fill utilized to mitigate settlement since 2016 amounted to approximately 140 cubic yards.
2019 - In February, the licensee detected further turbine building slab settlement of 1/8 inch near the isophase bus duct cooler and MCC E31A. In October, the licensee determined through eight monitoring points that no discernible settlement of the concrete slab had occurred in the north turbine building.
2020 - In March, during performance of main transformer deluge test, leakage was detected from a firewater flange downstream of valve FP129. In April, the licensee observed that the turbine building slab settlement continued, ranging from 1/4 to 3/8 inches. The licensee noted the rate of settlement had been significantly reduced due to the 2018 flowable fill injections. In September, the licensee removed the expansion joint along a portion of the north turbine building wall to enable engineering inspections for potential voiding between the floor and building foundation. In November, the licensee discovered a cracked firewater flange downstream of valve FP130. This flange was situated in the transformer deluge pit, located inside the north wall of the turbine building.
2021 - In August, the licensee replaced flanges in firewater lines FP123, FP129, and FP130 with more flexible Mega-flanges.
2022 - In July, the licensee determined that the maximum turbine building slab settlement since April 2018 was approximately 1/2 inch, equating to an average annual settlement of 1/8 inch. The total settlement of the turbine building slab reached slightly over 4 inches.
Monitoring activities revealed that the settlement rate was lower than the previous rate observed before the fill injections in 2018. However, continued settlement was attributed to the partial filling of voids in 2018. The licensee identified buried drain piping failures as a factor contributing to further ground settlement and voiding beneath the slab. These failures were believed to have played a role in the fire protection flange failures observed inside the turbine building wall from 2016 through 2020, as well as the underground firewater main failure outside the northern turbine building in October. Specifically, a catastrophic failure occurred in the buried 10-inch firewater main line FP123 located immediately north of the turbine building, resulting in the loss of fire protection functionality for approximately 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
The failure of the gray cast-iron pipe, which is a non-ductile material, was attributed to ground settlement. The affected section of the pipe was replaced with ductile iron and backfilled with self-compacting stone. In November, during the investigation of the firewater line break in FP123, it was determined that pipe FP129 had not bottomed out on the wall penetration and did not require re-leveling. However, it was discovered that the piping downstream from FP130 did not have a thrust block at the first change of direction. To prevent future deflection, the licensee installed a thrust block in this location.
Circulating Water System The condenser circulating water system is designed to accommodate the maximum heat loads of the condenser. It comprises a closed system that utilizes a hyperbolic natural draft cooling tower, along with circulating water pumps, piping, and valves. The fill and makeup water for the system are sourced from Lake Erie through the intake water system and intake structure. The system operates with four circulating water pumps, which draw water from the cooling tower discharge channel, pump it through the condenser, and then return it to the cooling tower.
The circulating water system, including the cooling tower, is classified as non-safety related.
Although it does not play a role in supporting any engineered safety features, the loss of circulating water would lead to a transient, disrupting reactor stability.
Cooling Tower The cooling tower consists of a reinforced concrete shell at its base, standing at a height of 493 feet above the basin sill. The shell is supported by a 13-feet-wide ring footing, which rests on compacted granular fill ranging from 6 to 8 feet in thickness. This compacted granular fill is underlain by a layer of till deposit, which in turn sits on bedrock. To mitigate potential excessive settlements, remedial grouting has been carried out on the cooling tower basin.
2006-2010 - Survey data for the cooling tower did not reveal any significant settling of the cooling tower structure.
2010 - The licensee identified and repaired cracks in the cooling tower basin slab and its liner.
2011 - The licensee repaired the basin slab near the canal interface and near the desilting trench.
2014 - The licensee identified and repaired cracks in the basin near loop two bypass. The licensee identified seal degradation between the piping and the basin wall which resulted in ground erosion from under the piping.
2016 - The licensee repaired sections of the basin slab and liner. The licensee injected grout into the subgrade during these repairs.
2020 - The licensee repaired a section of basin slab near mouth of canal.
2022 - The licensee identified settlement of the ring foundation and voiding beneath it. They repaired a separated basin-to-canal membrane and injected flowable fill. The license also established the Cooling Tower Restoration Project, which is discussed in more detail in the assessment for Charter Item 3.
Ground Between the Lake Erie Intake and the Main Plant Facility Since 1988 - The licensee observed underground leaks between the lake intake structure and main plant facility as early as 1988. The licensee attributed most of these underground leaks to significant plant construction activities like building additions and asphalt installation over previously grassed areas. The underground leaks originated from systems like fire protection, backwash sump discharge, domestic water, storm and sanitary sewers, and condenser pit drains.
1987-1995 - The licensee determined surface loading and excavation activities caused or significantly contributed to underground leaks and ground settlement.
2007 - The licensee determined that the condensate sump and backwash pipeline experienced internal corrosion, necessitating piping replacement.
2008-2011 - Replacement of the condensate sump and backwash pipeline led to substantial excavations from 2008 through 2011. This excavation work led to additional ground settlement in the area between the intake and the main plant facility.
2012 - The licensee excavated a surface depression at the southeast corner of the turbine building and discovered a broken sanitary drainage pipe and a ground void approximately 50 feet long, 30 feet wide, and 4 feet high. The licensee hired a contractor to address the void. The resolution process spanned across 2013.
Circulating Water 108-Inch Concrete Pipe Section Seals The circulating water 108-inch lines transfer circulating water between the cooling tower and the main condenser. They are routed between the pump house at the northwest corner of the turbine building, across the northern end of the protected area, to the cooling tower.
Since 2008, the licensee observed degraded grout at the joints of the 108-inch circulating water concrete pipe section. This degradation allowed water to leak and created areas of ground settling above these leaks. The licensee documented 31 condition reports associated with ground settlement related to circulating water pipe joints.
In 2020, the licensee completed repairs for all pipe joint leaks at the completion of refueling cycle 21. As part of their ongoing efforts, the licensee continues to regularly monitor pipeline repairs with walkdowns of top surface conditions.
Fire Suppression Systems The fire suppression systems serve several important functions, including providing water for automatic and manual fire suppression systems, confining fires for extinguishment, protecting structural steel associated with fire barriers, and maintaining fire barrier integrity.
Over the years, there have been multiple instances of buried fire suppression system leaks within the owner-controlled area, spanning from the late 1980s to the present. Among the events occurring within the risk-significant protected area of the plant, most of the underground fire suppression leaks have taken place between the intake and main plant facility.
Approximately 30 percent of notable underground leak events reported between the lake intake and main plant facility are associated with the buried fire suppression systems.
Noteworthy instances of fire suppression leaks began in 1988, shortly after the completion of the personnel support facility addition to the turbine building. Subsequent occurrences took place in 2007, 2008, 2015, 2016, 2018, 2021, and 2023.
Safety-Related Structures The foundations of safety-related structures mostly bear on bedrock. No instances of settlements in structures directly bearing on bedrock have been observed. Safety-related structures not bearing directly on bedrock, such as underground electrical duct banks, service water tunnels, and borated water storage tanks, according to the licensees Structures Monitoring Program procedure, could be affected by ground settlement.
The safety-related duct banks, which are routed beneath the settling turbine building concrete flooring slab, carry power cabling for motor control center F12C in the intake structure. The duct bank supplies power to the safety-related service water pumps, cooling tower makeup pump, the auxiliary transformer, and nonessential unit substation EF4.
The safety-related service water tunnel is located between the Auxiliary Building and intake structure. This reinforced concrete tunnel is buried underground and serves as a protective enclosure for service water pipes and other minor pipes. The service water pipe tunnel structure measures 12 feet in height, 11 feet in width, and spans a length of 360 feet. It connects service water valve room No. 1 in the turbine building with service water valve room No. 2, adjacent to the intake structures.
1986 - The licensee documented a fire protection pipe break and subsequent repair located south of the service water tunnel. However, the available records did not provide details regarding the proximity of the pipe break to the safety-related tunnel.
1988 - The licensee documented the identification and repair of a 1-foot-diameter void beneath the buried electrical duct bank adjacent to the diesel oil storage tank.
2008 - The licensee discovered an underground firewater leak between the lake intake and main plant facility, necessitating the addition of structural backfill in the service water tunnel areas. During the excavation to repair this firewater leak, the licensee discovered a 3-inch condensate demineralizer backwash pipe leaking nearby. The condensate pipe was routed at a height of 9 inches to 2 feet above the service water tunnel. The licensee replaced the pipe and backfilled the areas above the service water tunnel.
2016 - The licensee evaluations of voiding beneath the turbine building flooring determined that areas of voiding, situated approximately 4 to 5 feet below grade, were not low enough to impact the design function of the duct bank and their associated cabling. The duct bank was 10 feet below grade.
2018 - The licensee expanded the scope of repair for the voiding beneath the turbine building slab. During this scope expansion, the licensee determined the safety-related duct bank, a 3-inch-thick concrete structure, was not impacted by the floor slab because it was not gross settlement, and it was reasonable to conclude no change to the loading on the duct bank from the slab, or slab loads.
2022 - After the buried firewater main FP123 ruptured, the licensee did not assess the impact of the failure and the resulting ground settling on the safety-related duct bank situated beneath the turbine building floor slab. Despite the failure occurring within a proximity of 15 feet from the duct bank, which should have triggered an evaluation as per procedure EN-DP-01511, step 6.3.8, the licensee did not conduct an evaluation of the safety-related duct bank. The reason for this omission was the lack of any indication that the washed-out area had affected either the turbine building slab or the duct bank when the excavation took place.
Prior NRC Activities Related to Ground Settling at Davis-Besse Nuclear Power Station 2010 - On August 27, 2010, the NRC received the station's License Renewal Application. The application included a discussion concerning structure settlement, asserting that the need for managing structure settling was not warranted.
2016 - On April 30, 2016, the NRC issued its approval of the License Renewal Application, without an explicit provision specifically addressing the management of structure or ground settling.
2019 - The NRC conducted a Problem Identification and Resolution inspection that noted the licensee was not addressing ground settlement holistically. This observation was documented in NRC Inspection Report 2019010 (ML19252A853).
2022 - NRC inspectors review the CAP for potential adverse trends related to ground settling.
Inspection Report 2022004 (ML23038A204) stated the inspector determined that the ground settling examples reviewed may indicate a potential weakness when viewed in aggregate.
Assessment 93812 Charter Item 2 - Review the licensees evaluations of the ground settling occurrences and their potential impact to risk-important SSCs. This includes reviewing ongoing and planned monitoring and mitigation activities.
The team identified several observations related to the licensee's assessment and response to ground settling. Importantly, the team did not identify any immediate safety concerns with risk-important SSCs.
1. The team determined the licensee has not undertaken a comprehensive assessment
of the widespread ground settling across the site and its potential effects on risk-important SSCs. The licensee has historically attributed ground settling to various factors on a case-by-case basis, including backfill dissolution, backfill washout, heavy loads, backfill quality, and construction activities, as well as soil natural settlement.
While most instances of ground settling were attributed to backfill washout caused by non-radioactive underground pipe leaks, the licensee did not provide information demonstrating that the leaks preceded ground settling. Furthermore, the team noted examples of backfill settlement without evidence of washout, such as from pipe leaks.
The direct causes for these examples remain uncertain. Also, initial construction photos show surface depressions caused by ground dissolution.
2. The licensee indicated that their number of underground piping failures aligned with
the industry trend. However, the team noted the industry data gathered by the licensee did not support this. According to the data, the average failure rate over a 5 to 10-year period was 0.48 failures per year, with a median failure rate of 0.3 failures per year. Over a 15-year period, the licensee had a failure rate of 0.53 failures per year. Notably, they encountered five failures within a 5-year period, resulting in an elevated rate of 1.0 failure per year.
3. The team noted the possibility of bedrock dissolution based on the site's susceptibility,
and historical instances of bedrock dissolution beneath the cooling tower. However, the team did not have any immediate safety concerns because they did not observe any bedrock dissolution or settling of structures directly anchored on bedrock. The licensee believes bedrock has remained unchanged due to the absence of observed solution activity in nearby quarries, the Bedrock Verification Program conducted during initial construction, and the equilibrium of groundwater chemistry with gypsum at that time. However, the team noted these factors regarding bedrock dissolution:
a.
The licensees geotechnical evaluation for initial construction stated that there was no hydraulic gradient across the site, and that the ground water regime must be maintained to avoid bedrock dissolution. However, the Updated Final Safety Analysis Report mentioned intermittent reversals in groundwater flow towards Lake Erie due to lake level changes and the licensees groundwater data showed there is a hydraulic gradient at the site that changes with time.
b.
During construction, the licensee discovered dissolution of the bedrock beneath the cooling tower and addressed it by grouting the affected areas.
The effectiveness of this mitigation remains unverified, and the licensee did not provide information to rule out bedrock dissolution as a contributor of the cooling tower backfill settlement.
c.
The team observed 45-degree cracks on multiple Auxiliary Building walls anchored in bedrock. The licensee is monitoring crack growth and has determined no further action is currently required based on the American Concrete Institutes guidance. The licensee has not considered differential settlement as a potential cause, and the reason for their presence remains uncertain.
4. The licensee determined the cooling tower settlement was caused by a combination
of age-related degradation of the membrane surrounding the cooling tower basin, resulting in water flowing into the ground below and causing backfill washout. Signs of washout and settling were observed as early as spring 2014. On April 12, 2023, the licensee initiated a causal evaluation of the cooling tower settlement.
5. The licensees procedure EN-DP-01511, Structures Monitoring, established to
implement, in part, provisions of the Maintenance Rule and License Renewal Programs, included instructions for monitoring settlement. As discussed in the NCV within this report, the licensee introduced these instructions in response to an earlier NRC inspection observation that they were not addressing ground settlement holistically. The team noted the following:
a.
Portions of the procedure addressing ground settling were not being implemented. Step 6.3.8.a required evaluations of ground settling within 15 feet of safety-related structures not bearing on bedrock. However, the licensee did not have records of evaluations of five out of six ground depressions documented within 15 feet of such structures, which were identified since the introduction of this step in the procedure. The team determined this was a finding with an associated NCV, as described later in this report.
b.
The procedure did not address ground settling near non-safety-related structures. Although both the Maintenance Rule and License Renewal Programs covered safety and risk-important non-safety-related structures, step 6.3.8.a of the procedure solely focused on safety-related structures. The licensees position is that step 6.3.8 provided general instructions for addressing areas exhibiting ground settling, while step 6.3.8.a emphasized the importance of safety-related structures. However, the team noted that step 6.3.8 did not provide any instructions or directed actions. It simply stated Settlement: Apparent excessive total or differential settlement based on visual inspection. Thus, the procedure only required evaluations of ground settling within 15 feet of safety-related structures. Moreover, the licensee did not provide any evaluations for non-safety related but risk-important structures.
The licensees position is that evaluations were performed but not documented because there is no requirement to document them.
Assessment 93812 Charter Item 3 - Review the reasonableness of the licensees CAP at addressing internal and external operating experiences involving ground settling, including determining how the licensee considered any relevant plant-specific operating experience related to ground settling in support of their License Renewal Application.
General Ground Settling Response The licensee's CAP has documented well over 100 corrective action documents related to ground settlement, with most of them occurring since 2002. However, despite of the number of ground settling zones around the site and notable examples such as settlement of the cooling tower and turbine building portions, as well as recent adverse impacts to the firewater system, the licensee has not recognized ground settling as a site-wide issue warranting a comprehensive review.
The NRC conducted a Problem Identification and Resolution inspection in 2019, which noted that the licensee was not addressing ground settlement holistically. This observation was documented in NRC Inspection Report 2019050 (ML19252A853). In response, the licensee revised procedure EN-DP-01511, Structures Monitoring, by adding an instruction to evaluate safety-related structures not bearing directly on bedrock whenever a ground depression is identified within 15 feet of such structures. However, this instruction was limited to safety-related structures and did not extend to all structures important to safety. In addition, the licensee did not have records of evaluations of five out of six ground depressions documented within 15 feet of such structures, which were identified since the introduction of this step in the procedure, as outlined in the NCV documented in this inspection report.
The NRC identified a finding of very low safety significance (Green) for the licensee's failure to address an identified adverse condition on a portion of piping in the firewater system. This finding is discussed elsewhere in the Results section of this report.
Turbine Building Settlement Response As per the timeline included in Charter Item 1, a specific instance highlighting the licensee's response to ground settling is associated with the turbine building. A portion of this building, which is not supported by bedrock, and the surrounding ground, experienced settlement. The licensee attempted to halt the settling by injecting approximately 140 cubic yards of flowable fill into an underground void in 2016 and 2018, after the turbine building slab had already settled by approximately 4 inches. Following the flowable fill injection, the building continued to experience settlement at a slower rate, with an additional settlement of approximately 5/8 inches recorded as of this inspection.
Cooling Tower Settlement Response As discussed in the timeline included in Charter Item 1, the non-safety-related cooling tower, which is supported by backfill, has experienced settlement. Over the last 15 years, the structure has undergone multiple repairs, but degradation continues to persist. In 2022, the licensee identified settlement of the ring foundation and voiding beneath it. In response, they repaired a separated basin-to-canal membrane and injected flowable fill. In the same year, the licensee also established the Cooling Tower Restoration Project with plans to address the settling by: 1) installing micropilings in areas where the support piers have settled; 2) restore full support to the circulating water and bypass piping; 3) extend the basin walls back to original elevation height; 4) remove and restore the slab, membrane, and subgrade near the canal; and 5) perform ground-penetrating radar to identify and address any other voiding areas. The licensee expects to complete these activities by spring 2024.
Ground Settlement Considerations in License Renewal Application The team did not find any site-specific operating experience involving ground settling occurring prior to the License Renewal Application submittal that should have been considered during the License Renewal review. License renewal is the process of extending the operating licenses of nuclear power plants beyond their initial expiration dates, with aging management programs and activities to monitor and mitigate the effects of aging on SSCs to provide reasonable assurance they will continue to perform their intended functions for the period of extended operation.
The License Renewal Application was submitted in 2010 and stated that no aging management program was required for structure settlement, based on geotechnical evaluations conducted during the initial construction of Class 1 and 2 structures. These evaluations stated that no long-term settlement of the structures was anticipated after construction. Although the License Renewal Application mentioned a separate instance of settlement-related operating experience, it was unrelated to the ground settlement issues addressed in this inspection. Specifically, it was related to intake canal embankment slope stability.
The team also noted potential limitations in the licensees approach for managing the effects of aging for the buried portions of the fire protection system. The licensees methodology, which was endorsed by the NRC during License Renewal review, relies on a form of leak rate monitoring. Conceptually, any unexplained increase in system leakage can identify age-related degradation prior to a loss of intended function. However, the firewater system experienced a rupture in 2022, just 1 day after the last leak rate measurement, despite consistent leakage for the previous 5 weeks leading up to the failure. Based on this information, the leak rate monitoring for the brittle gray cast-iron piping did not appear to provide any indication of system degradation prior to the loss of intended function during the 2022 event.
Failure to Address External Bending Loads on the Firewater System Due to Ground Settling Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green FIN 05000346/2023050-01 Open/Closed
[P.1] -
Identification 93812 The team identified a finding of very low safety significance (Green) for the licensees failure to address an adverse condition (i.e., external bending loads) on a portion of the firewater system piping. Specifically, on August 10, 2021, the licensee noted a portion of fire protection system piping was deflected downward and no longer supported properly. They considered ground settlement as a likely cause. However, they did not evaluate the potential effects of the condition as required by procedure NOP-LP-2001, Corrective Action Program.
Description:
On June 30, 2016, the licensee documented a through-wall leak on a flange in the firewater system piping as Condition Report (CR) CR-2016-08333 within their CAP. The affected section of piping transverses through the turbine building wall, with portions located inside the building and others outside. The external segments of the pipe are buried underground, while the cracked flange was located inside the building. To address the leak, the licensee isolated the affected section of piping to mitigate the leakage rate. There was no further documentation regarding whether the leak was fully stopped or any information on the initial and final leak rates to assess the success of the isolation. Subsequently, the licensee closed the CR to notification 601048984, which was processed into work order (WO) 200685865.
On August 10, 2021, the licensee initiated repairs on the cracked flange by implementing WO 200685865. To prevent a recurrence of failure, the licensee opted to replace the cracked flange with a more robust alternative known as MegaFlange. During the repair/replacement activity, the licensee documented in the WO that the probable cause of failure was "Abnormal Stress." In addition, they documented that they "believed that the outside pipe is pushed down due to settlement." However, no new CR was initiated for this condition, and it was not further addressed under the existing CR or WO.
On October 10, 2022, the buried portion of the repaired firewater pipe ruptured. Upon evaluating this failure, the licensee documented that the earlier repair had relieved stresses at the repaired location but had not relieved the stresses at the other end of the pipe where the recent failure occurred. In addition, it was documented that the piping had bottomed out against the pipe penetration, causing additional pipe stresses. The final failure mode analysis determined "the combination of external bending loads (caused by soil movement and the subsequent bottoming out of the FP122/FP123 pipe against the bottom of the wall penetration and concentrated by the thrust constraints) and hoop stress (normally present due to internal firewater pressure), resulted in a mixed-mode failure manifested in an approximately 45-degree diagonal fracture." In addition, the licensee documented "the MegaFlange installed 8/2021 accommodated the shifting of the pipe between the building and 1st buried flange, but without the buried pipe being raised back up to its original height, stresses remained at the bolt holes of the first buried flange."
NOP-LP-2001, "Corrective Action Program," Revision 48, Step 4.1.2 states, in part, that "All CAQ [Condition Adverse to Quality] and CARC [Condition Adverse to Regulatory Compliance] issues, regardless of significance level, shall be entered in the condition report process and the associated electronic database unless listed as an exception in Section 2.2."
Section 2.2 described the exceptions to the program and are limited to performance management of personnel (i.e., human resources issues) and safeguards and security sensitive conditions. Section 4.3.2 stated, in part, "CRs shall be initiated for any issue, event, defect, characteristic that could credibly impact nuclear safety, personnel safety, plant reliability or compliance with federal, state or local regulations." Section 3.1 of the procedure defined a CARC as A condition in which the licensee is not in conformance with NRC regulations; a failure to comply with a docketed commitment made to the NRC; a non-compliance with the licensees Quality Assurance Program that does not consequently affect the safety-related function of a structure, system or component." Attachment 1 of NOP-LP-2001 provided examples of items that met the definition of a CARC. This attachment stated in part, "Conditions Adverse to Regulatory Compliance are addressed within the licensee corrective action program." In addition, Example 5 stated that a CARC includes "A condition adversely affecting performance in Initiating Events, Mitigating Systems or Barrier Integrity. This includes issues involving:...fire protection..." Section 4.6.3 established the method to evaluate the condition based on the cause uncertainty and risk/consequence to the station. Section 4.9.3 dictated the resolution needed to address the condition identified (i.e., Rework, Repair, or Use-As-Is).
Corrective Actions: The piping was replaced as a result of the failure and the misalignment was corrected to address the stresses. In addition, the licensee planned to perform an extent of condition of the remaining pipes passing through the same wall section to identify any potential instances of unacceptable stresses.
Corrective Action References: CR-2023-05000
Performance Assessment:
Performance Deficiency: The team determined the licensee's failure to address an adverse condition on the fire protection system as required by NOP-LP-2001, "Corrective Action Program," was a performance deficiency. Specifically, on August 10, 2021, the licensee noted a portion of fire protection system piping was deflected downward and no longer supported properly. They considered ground settlement as a likely cause. However, they did not capture the condition in their condition report process, assign an evaluation method, and correct it.
Screening: The inspectors determined the performance deficiency was more than minor because if left uncorrected, it would have the potential to lead to a more significant safety concern. Specifically, not addressing adverse conditions in accordance with the CAP can lead to more significant concerns, such as loss of risk-important functions.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. In consultation with Senior Reactor Analysts, the team determined the performance deficiency was not the proximate cause of the 2022 firewater pipe failure. Specifically, between August 10, 2021, and October 20, 2022, the available time was insufficient to evaluate and implement corrective actions to prevent the subsequent failure in the firewater system. Thus, IMC 0609 Appendix A was applicable. The finding was determined to be of very low safety significance (Green) because the team answered "no" to all the questions in Exhibit 2 - Mitigating Systems Screening Questions.
Cross-Cutting Aspect: P.1 - Identification: The organization implements a corrective action program with a low threshold for identifying issues. Individuals identify issues completely, accurately, and in a timely manner in accordance with the program. In this context, the licensee observed that a portion of the firewater system piping exhibited deflection and inadequate support. However, they failed to fully recognize and identify this issue as an adverse condition that needed to be addressed in accordance with their CAP.
Enforcement:
Inspectors did not identify a violation of regulatory requirements associated with this finding.
Failure to Evaluate Ground Depressions Identified within 15 Feet of Safety-Related Structures Not Bearing in Bedrock Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000346/2023050-02 Open/Closed
[H.1] -
Resources 93812 The team identified a finding of very low safety significance (Green) and an associated Non-Cited Violation of 10 CFR 50, Appendix B, Criterion V, "Instructions, Procedures and Drawings," when the licensee failed to evaluate the effects of ground settling on safety-related structures in accordance with procedure EN-DP-01511, Structures Monitoring. Specifically, the licensee failed to perform evaluations of five areas with ground settling identified within 15 feet of safety-related structures not bearing on bedrock as required by procedure step 6.3.8.
Description:
In 2019, the NRC conducted a Problem Identification and Resolution inspection that noted the licensee was not addressing ground settlement holistically. This observation was documented in NRC Inspection Report 2019010 (ML19252A853). In response, on November 20, 2019, the licensee revised procedure EN-DP-01511, Structures Monitoring.
This procedure establishes responsibilities, requirements, and guidelines for performing periodic inspections as required by Maintenance Rule and License Renewal. The inspections aim to monitor structural conditions and identifying age-related degradation. Additionally, the procedure includes instructions for inspections not required by the Maintenance Rule and License Renewal, but they are intended to further monitor structural conditions and age-related degradation.
Following this revision, step 6.3.8 was added to the procedure to require the evaluation of safety-related structures not bearing directly on bedrock, as shown on Attachment 8 of the procedure, whenever a ground depression is detected within 15 feet of such structures.
Examples of structures described in Attachment 8 include the safety-related service water tunnel, electrical duct banks, borated water storage tank, and dry cask storage pad.
On May 5, 2023, the team requested evaluations completed in accordance with step 6.3.8 of EN-DP-01511, as specified in Revision 14 of the procedure. The licensee responded on May 8, providing a list of condition reports documenting ground depressions within 15 feet of safety-related structures not bearing on bedrock. However, out of six condition reports, only one included an evaluation that met the requirements of procedure EN-DP-01511. On May 16, 2023, the licensee clarified that no formal evaluations had been documented for the remaining five instances. Specifically, the licensee failed to evaluate the effects of ground depressions identified within 15 feet of the safety-related MH3001 electrical duct bank (CR-2023-01677, CR-2022-07575, and CR-2021-05651) and service water tunnel (CR-2023-03114 and CR-2021-05651). Although the licensee asserted that informal evaluations had been conducted but not documented, the team noted that such informal evaluations did not comply with the rigorous quality controls required for safety-related activities by their Quality Assurance Program.
The safety-related service water tunnel is a structure through which service water piping portions are routed among other fluid systems. The safety-related MH3001 duct bank routes safety-related power cabling to motor control center F12C in the intake structure, which powers safety-related service water pumps. The duct bank is located beneath the turbine building floor slab, which is experiencing settling and is in proximity to a ground void.
Although the licensee assessed the operability of the MH3001 electrical duct bank in condition reports CR-2016-13526 and CR-2018-03630 in 2016 and 2018, respectively, and the settling rates of the turbine building slab have decreased since the injection of 140 cubic yards of flowable fill in 2016 and 2018, the licensee documented additional ground settling within 15 feet since 2019 without evaluating their impact on the duct bank in accordance with EN-DP-01511.
Corrective Actions: The licensee created an assignment to perform an organizational effectiveness investigation which will include an extent of condition review. In a discussion with the team, the licensee confirmed their intent to develop corrective actions to restore compliance using the results from their investigation.
Corrective Action References: CR-2023-04944
Performance Assessment:
Performance Deficiency: The team determined the licensee's failure to evaluate the effects of ground settling identified within 15 feet of safety-related structures not bearing on bedrock was contrary to licensee procedure EN-DP-01511, "Structure Monitoring," and was a performance deficiency.
Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Equipment Performance attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the failure to evaluate the effects of ground settling on nearby safety-related MH3001 electrical duct bank and service water tunnel does not ensure the availability and reliability of the supported mitigating systems, such as the safety-related service water system.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The finding was determined to be of very low safety significance (Green) because the team answered "no" to all the questions in Exhibit 2 - Mitigating Systems Screening Questions.
Specifically, the finding did not involve the loss of operability or functionality.
Cross-Cutting Aspect: H.1 - Resources: Leaders ensure that personnel, equipment, procedures, and other resources are available and adequate to support nuclear safety.
Specifically, the licensee's leaders failed to ensure that personnel performing the ground settling evaluations applied all quality assurance requirements to support nuclear safety.
Enforcement:
Violation: 10 CFR 50 Appendix B, Criterion V, Instructions, Procedures and Drawings, requires, in part, activities affecting quality to be prescribed by documented instructions, procedures, or drawings of a type appropriate to the circumstances, and be accomplished in accordance with these instructions, procedures, or drawings.
Contrary to the above, since July 25, 2021, the licensee failed to accomplish activities affecting quality in accordance with instructions, procedures, or drawings. Specifically, on November 20, 2019, the licensee revised procedure EN-DP-01511, Structures Monitoring, to require the evaluation of safety-related structures not bearing directly on bedrock, as shown on Attachment 8 of the procedure, whenever ground settling is detected within 15 feet of such structures. Since the procedure was revised, the licensee identified five ground depressions within 15 feet of MH3001 electrical duct bank (CR-2023-01677, CR-2022-07575, and CR-2021-05651) and the service water tunnel (CR-2023-03114 and CR-2021-05651).
However, the licensee failed to evaluate the effects of these ground depressions on these safety-related structures included in Attachment 8 of procedure EN-DP-01511, which are not bearing on bedrock. The licensee indicated that they conducted informal evaluations, but the team noted these were insufficient to meet the procedural requirement. The evaluations required by the procedure are activities affecting quality, as they assure that safety-related functions are maintained by confirming ground settling is not adversely affecting safety-related structures or identifying degraded conditions requiring repairs. As such, these evaluations necessitate rigorous quality controls that cannot be applied informally.
Enforcement Action: This violation is being treated as a non-cited violation, consistent with Section 2.3.2 of the Enforcement Policy.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
On April 28, 2023, the inspectors presented the Onsite Debrief inspection results to Terry Brown, Site Vice President, and other members of the licensee staff.
On May 19, 2023, the inspectors presented the Interim Exit inspection results to Terry Brown, Site Vice President, and other members of the licensee staff.
On June 23, 2023, the inspectors presented the special inspection results to Terry Brown, Site Vice President, and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
CR-2013-10643
Sink Hole Outside Turbine Building North Roll-Up Door 334
07/11/2013
CR-2019-05840
2019 NRC PI&R: Evaluate Approach to Address Sinkholes
07/10/2019
CR-2019-05889
2019 NRC PI&R: Minor Violation for Maintenance Rule and
Aging Management Evaluations for Sinkholes
07/11/2019
CR-2021-02350
Sink Hole in Owner Controlled Area
03/29/2021
CR-2021-04199
Small Sinkhole Identified South of Wellness Center
05/24/2021
CR-2021-04366
Potential Sinkhole Near Water Treatment Plant
06/01/2021
CR-2021-04728
Sinkhole Identified in Security Isolation Zone
06/16/2021
CR-2021-05651
Potential Sinkhole North of Circ Pump House
07/25/2021
CR-2021-05696
Sink Holes in the Protected Area
07/27/2021
CR-2021-08529
Sinkhole Under Sidewalk
11/08/2021
CR-2022-01260
Degraded Storm Drain and Sinkhole Identified in ROCA
2/18/2022
CR-2022-02401
Cooling Tower Bypass Pipe Support Settlement/Sinkhole
03/19/2022
CR-2022-03999
Security Zone 9 Sink Holes Continue to Get Worse
05/11/2022
CR-2022-06310
Sinkhole Training Center Contractor Lot
08/16/2022
CR-2022-07031
Possible Sink Hole/ Trip Hazard Along Safe Walkway
Southwest of the Primary Access Facility
09/15/2022
CR-2022-07575
North Underground Fire Protection Loop Pipe Rupture
10/10/2022
CR-2022-07790
Potential Sinkhole Near AC Transformer
10/15/2022
CR-2022-09856
Potential Sink Hole Identified in Personnel Walkway between
PSF and South PAC
2/29/2022
CR-2023-00052
Sinkhole Near Safe Walkway Zone 5
01/04/2023
CR-2023-00594
Turbine Building Ground Sinking/Unlevel
01/27/2023
CR-2023-01041
Sinkhole Degrading Fence in Zone 5
2/15/2023
CR-2023-01458
Sinkhole Appeared Near the West Gate of the Circ Water
Canal
03/01/2023
CR-2023-01677
Underground Fire Protection Leak Causes Electric Fire Pump
to Auto Start
03/07/2023
CR-2023-02918
108" Potential Sinkholes Summary
04/12/2023
93812
Corrective Action
Documents
CR-2023-02948
Conditions Outside of Original Design Tolerance Identified
While Mapping the Cooling Tower
04/12/2023
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
CR-2023-03114
Ground Settling Between Old Office Building and Intake
Structure
04/16/2023
CR-G201-2002-
216
East Condenser Pit Has Diesel Fuel Oil Entering from an
Unknown Source
08/14/2002
CR-G201-2002-
08323
Water "Gushing" Through the Wall into the Motor Driven
Feed Pump Area
10/18/2002
CR-G201-2003-
00494
Potential Fire Protection Piping Leak
01/21/2003
CR-G201-2005-
05713
Electric Fire Pump Auto Start Due to Leak in System
11/23/2005
CR-G201-2005-
05987
Sinkholes Located Near Wooden Walkway by Vault 100
2/28/2005
CR-G201-2006-
273
Possible Sinkhole Near Fire Hydrant 13
05/12/2006
CR-G201-2006-
2309
Sink Hole Located
05/17/2006
CR-G201-2006-
2346
Sink Hole Located
05/21/2006
CR-G201-2006-
2465
Sink Hole Near Wooden Walkway
06/03/2006
CR-G201-2006-
2699
Sinkhole at Service Building #6
06/29/2006
CR-G201-2006-
2779
Sinkhole Inside the Protected Area
07/11/2006
CR-G201-2006-
11140
Sinkhole East of Old Office Building
2/08/2006
CR-G201-2007-
15989
Sinkhole Found in the Protected Area
03/11/2007
CR-G201-2007-
214
A New Sinkhole Was Discovered Near the Start-Up
Transformers
03/14/2007
CR-G201-2007-
17117
Sinkhole East of PSF
03/29/2007
CR-G201-2007-
20136
Unexpected Auto Start of Electric Fire Pump
05/07/2007
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
CR-G201-2007-
20863
Tutorial CR
05/20/2007
CR-G201-2007-
21754
Grounding Wires Outside of LLRW Building Stretched and
Clamps Pulled Free
06/07/2007
CR-G201-2007-
2680
A New Sink Hole Has Developed Next the Fire Water Test
Header Platform
06/27/2007
CR-G201-2007-
23574
Issue in Analysis of Ground Water Monitoring Sample
Results
07/16/2007
CR-G201-2007-
26481
WANO 2007 - AFI ER.3-2, Buried Piping and Cathodic
Protection
09/12/2007
CR-G201-2007-
230
Possible Sink Hole Near Hose House 13
10/26/2007
CR-G201-2008-
2996
108" Circ Water South Pipe Joint Leak
01/09/2008
CR-G201-2008-
34441
Gross Leakage Identified on Circ Water North 108" Cooling
Tower Return Line
01/28/2008
CR-G201-2008-
35563
Possible Sinkhole Developing East of PSF
2/19/2008
CR-G201-2008-
39459
Sink Hole
04/30/2008
CR-G201-2008-
41167
Loss of the Turbine Building Domestic Water Header
06/03/2008
CR-G201-2008-
41830
Sink Hole
06/15/2008
CR-G201-2008-
44824
Possible Sinkhole
08/15/2008
CR-G201-2008-
45666
Possible Sinkhole Forming Under Sulfuric Acid Tank, North
of Water Treatment
09/02/2008
CR-G201-2008-
47504
Broken Sewer Line Found East Side of PSF
10/07/2008
CR-G201-2008-
47596
Domestic Water Leak Found
10/09/2008
CR-G201-2008-
47835
Electric Fire Pump Start Due to Apparent Leak in Fire
Protection System
10/14/2008
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
CR-G201-2008-
288
Leaking Pipe Found
10/22/2008
CR-G201-2009-
53473
Sink Hole Developing East of Plant
2/13/2009
CR-G201-2009-
58566
Sinkhole Inside the Protected Area
05/04/2009
CR-G201-2009-
59505
Water Leaking from Pipe in Grassy Area Near Sewage
Treatment Plant
05/21/2009
CR-G201-2009-
2991
Sinkholes Forming North of the Protected Area Fence
08/10/2009
CR-G201-2009-
64067
Thru Wall Hole in Elbow - Underground PVC Domestic Water
Line to Circ Pumps
09/04/2009
CR-G201-2009-
68446
Sinkhole at East Side of PSF
2/01/2009
CR-G201-2009-
69100
Sinkhole Forming Inside of PA Perimeter Fence Zone.
2/16/2009
CR-G201-2010-
71890
Sinkhole Found from a Suspected Broken Sewer Force Main
2/22/2010
CR-G201-2010-
241
Discovered Water Leaking from Ground South of Intake
Structure
03/01/2010
CR-G201-2010-
255
Underground Line Break/Contaminated Leak - Tritium
03/01/2010
CR-G201-2010-
209
Sinkhole Found from a Suspected Broken Sewer Line
03/25/2010
CR-G201-2010-
76498
Increasing Tritium Trend in Groundwater Well MW-105A
05/06/2010
CR-G201-2010-
77198
Sinkhole Forming in the Protected Area
05/22/2010
CR-G201-2010-
80408
Sinkhole Forming in the NE Corner of the PA
07/28/2010
CR-G201-2010-
80966
Sinkhole Forming North of the Protected Area Fence
08/09/2010
CR-G201-2010-
2006
Sink Hole Developing Outside of the Protected Area Near
Pavilion
08/31/2010
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
CR-G201-2010-
2850
Sinkhole Forming Near Junction of Old Office Building and
Circ. Pump House
09/19/2010
CR-G201-2010-
83147
Underground Piping and Tanks Integrity Initiative
09/24/2010
CR-G201-2010-
86434
Sinkhole Forming on the Southeast Corner of the Protected
Area
11/30/2010
CR-G201-2010-
87632
Site Protection Officer Had Incident/Near Miss
2/31/2010
CR-G201-2011-
244
Sinkhole Forming in the Protected Area
03/01/2011
CR-G201-2011-
91803
Sink Hole Located in Security Zone East of the Circ. Water
Canal
03/26/2011
CR-G201-2011-
260
Sink Hole Identified on the East Side of the PA Near the
Delay Fencing
05/21/2011
CR-G201-2011-
95615
Sinkhole Forming in the Protected Area
05/28/2011
CR-G201-2011-
95854
Possible Sink Hole on the West Side of the Plant Near S/U
XFMR 02
06/02/2011
PCAQ-86-0094
Evaluate Potential for 30 Day Report
07/09/1986
PCAQ-88-0469
Grout Used as Backfill Is Not Allowed
06/24/1988
PCAQ-94-0232
Domestic Water Pipe Failure
2/29/1994
PCAQ-94-0855
Sinkhole at the Beach Station Caused by Pipe Leaking
10/01/1994
PCAQ-95-0529
A Discharge Line Leak at Sanitary Lift Station Causing Sink
Hole
06/21/1995
PCAQ-95-0636
Sink Hole Observed on the West Side of the Wet Wash
Facility
08/01/1995
PCAQ-95-0692
Sink Hole Discovered North and West of the Collection Box
08/18/1995
PCAQ-95-0964
A Sink Hole Was "Noted" West of BD Transformer
11/16/1995
PCAQ-96-0015
There Are Possible Voids Underneath the Roadway
Pavement Adjacent to Door 300
01/05/1996
PCAQ-96-0206
Fork Lift Wheel Went Through the Blacktop
2/27/1996
PCAQ-96-0208
A Sink Hole Was Noted About 30' Northwest of the #2 SU
Xfmr Just Outside the Vehicle Barrier
2/27/1996
PCAQ-96-0243
A Small Sink Hole Developing Between Inner and Outer
03/04/1996
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Security Fences
PCAQ-97-0093
A Sink Hole Was Observed Behind the Wet Wash Facility
(WWF)
01/24/1997
PCAQ-97-0856
The 4" Sanitary Force Main Near Lift Station #7 May Have a
Break Which Has Caused a Sink Hole to Form
06/23/1997
PCAQ-97-0877
A Sink Hole Has Formed Just North of the Aux Boiler Room
Roll-up Door Around Connection Box 13
06/25/1997
PCAQ-97-1020
Several Sink Hole Have Appeared Within the Protected Area,
Due to the Intense Thunderstorm of 7/26/97
07/26/1997
CR-2023-03456
North Switch Yard Gate Damaged Hardware and Found
Unlocked
04/24/2023
CR-2023-04944
Insufficient Documentation of Evaluations for Sink
Holes/Areas of Settlement within 15 Feet of Safety-Related
Structures
06/21/2023
Corrective Action
Documents
Resulting from
Inspection
CR-2023-05000
Failure to Address Adverse Condition (Fire Protection Piping
Misalignment) in Corrective Action Program
06/22/2023
ATL-2023-0343-
ATA-02
Turbine Building Foundation Drawings
04/25/2023
Drawings
ATL-2023-0343-
ATA-11
Foundation Drawings for the Low-Level Radwaste (LLRW)
Building and Auxiliary Building
04/27/2023
CR Disposition Final
05/16/2023
Operating Experience White Paper Final
05/12/2023
ATL-2023-0343-
ATA-01
Turbine Building Floor Settling Monitoring
04/25/2023
ATL-2023-0343-
ATA-03
Gypsum Transport in Bedrock
04/24/2023
ATL-2023-0343-
ATA-05
List of CRs/Evaluations Associated with North Turbine
Building Floor Settling
04/26/2023
ATL-2023-0343-
ATA-06
Flowable Fill Composition
04/25/2023
ATL-2023-0343-
ATA-08
Cooling Tower Plan of Action
04/26/2023
Miscellaneous
ATL-2023-0343-
ATA-13
LLRW Building Impact on Auxiliary Building
05/02/2023
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
ATL-2023-0343-
ATA-15
Phase I Report - Geology, Seismology, Subsurface
Conditions, and Preliminary Foundation Recommendations
for Proposed Davis-Besse Nuclear Power Station, Locust
Point, Ottawa County, Ohio
Prepared for The Toledo Edison Company Under the
General Direction of Bechtel Associates by Woodward-Clyde
& Associates, Inc.
07/18/1969
ATL-2023-0343-
ATA-21
Evaluation of Deficiencies in Structures Monitoring Program
05/08/2023
ATL-2023-0343-
ATA-28
Crack on EDG Room Wall Exterior
05/09/2023
ATL-2023-0343-
ATA-32
Groundwater Data
05/11/2023
ATL-2023-0343-
ATA-33
Lake Level Changes
05/10/2023
ATL-2023-0343-
ATA-34
Maximum TB Settlement
05/10/2023
ATL-2023-0343-
ATA-35
BMI Cooling Tower Report
05/09/2023
ATL-2023-0343-
ATA-36
Q-Class 1 Fill
05/10/2023
ATL-2023-0343-
ATA-40
Settlement Deflection Limits
05/10/2023
ATL-2023-0343-
ATA-44
Cooling Tower Causes
05/12/2023
EN-DP-01511
Structures Monitoring
EN-DP-01511
Structures Monitoring
MRPM 42
Maintenance Rule Program Manual
NOP-ER-3004
NOP-OP-1009
Operability Determinations and Functionality Assessments
Procedures
NORM-OP-1009
SRO Review of Condition Reports
Work Orders
MWO-1-88-1401
Two Sink Holes Have Developed on the East Side of the
PSF Near Hydrant #3 and Sanitary Lift Station #7
05/31/1988
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
MWO-1-88-2312
There is a Sink Hole That Needs Backfilling
07/01/1988
MWO-1-89-0225
A Sink Hole has Developed in the Area of FP0059
01/25/1989
MWO-1-89-0391
Sinkhole has Developed Near the South Entrance of the
Water Treatment Building
04/26/1989
MWO-1-90-1351-
An Area East of the Old Maintenance Shop's Overhead Door
is Sinking
06/14/1990
MWO-1-90-2175-
A Sink Hole Has Again Developed East of the Old
Maintenance Shop
10/18/1990
MWO-1-91-0764
Investigate the Sink Hole That Has Appeared Outside the
Old Maintenance Shop
05/21/1991
MWO-1-92-1073
A Sink Hole has Developed East of the PSF/Office Building
08/28/1992
MWO-1-93-1053
Sink Hole Areas Have Developed East of the Old Office
Building
08/13/1993
MWO-1-95-0753
A Sink Hole West of the Wet Wash Facility Appears to be
Growing
07/31/1995
MWO-7-95-0692
A Sink Hole Was Discovered North and West of the
Collection Box
11/06/1995
MWO-80-2776
Excavate Test Pit in Depression Area on Northwest Side of
Aux Building
07/02/1980
MWO-80-3047
Ground Subsidence in the Vicinity of Storm Sewer Line
Between Catch Basin #23 and Catch Basin #7
08/24/1980