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Nuclear Plants and Disasters: NRC Inspection Results

After the earthquake and tsunami crippled the Fukushima Daiichi plant in Japan, the Nuclear Regulatory Commission ordered an inspection of U.S. plants to check their preparedness for a catastrophic natural disaster or terrorist attack. Inspectors found problems at 60 of the 65 plants. Excerpts from the inspection reports are below. For help with acronyms, see this glossary. | Related Story: Nuke Plant Inspections Find Flaws in Disaster Readiness

Arkansas Nuclear One | Beaver Valley | Braidwood | Browns Ferry | Brunswick | Byron | Callaway | Calvert Cliffs | Catawba | Clinton | Columbia Generating Station | Comanche Peak | Cooper | Crystal River | Davis Besse | DC Cook | Diablo Canyon | Dresden | Duane Arnold | Farley | Fermi | Fitzpatrick | Fort Calhoun | Ginna | Grand Gulf | Harris | Hatch | Hope Creek | Indian Point 2 | Indian Point 3 | Kewaunee | Lasalle | Limerick | McGuire | Millstone | Monticello | Nine Mile | North Anna | Oconee | Oyster Creek | Palisades | Palo Verde | Peach Bottom | Perry | Pilgrim | Point Beach | Prairie Island Units 1 and 2 | Quad Cities Units 1 and 2 | River Bend | Robinson | St. Lucie | Salem | San Onofre | Seabrook | Sequoyah | South Texas Project | Summer | Surry | Susquehanna | Three Mile Island | Turkey Point | Vermont Yankee | Vogtle | Waterford | Watts Bar | Wolf Creek

Arkansas Nuclear One
NRC Inspection Report
Issues Cited:

  • Several of the portable flood control pumps were not functional. The licensee has sufficient numbers of portable pumps on hand to meet the B.5.b strategy. The licensee is verifying the adequacy of the process to ensure portable pumps are maintained in a functional status.
  • During walk downs, it was discovered that pre-marked locations for cutting access holes in the unit 1 spent fuel pool roof had been obscured during roof upgrade activities. These marks have been reapplied.
  • During walk downs, two pieces of passive equipment necessary to flood the Unit 1 or Unit 2 containment building via the escape hatches were not identified or staged with B.5.b equipment. The equipment has been obtained and staged. The procedure was changed to reflect the connections and equipment.

Beaver Valley
NRC Inspection Report
Issues Cited:

  • Although the station meets the current design and licensing bases for station blackout, the inspectors concluded that coping with a dual unit Station Blackout (a beyond design basis event) could present significant challenges. For example: the SBO cross-tie equipment is located in non-seismically qualified areas (normal switchgear) of each unit; and Unit 1 requires AC power to the MOVs to isolate the safety injection accumulators during RCS depressurization. The licensee documented the general issue of a dual unit SBO under CR 1 1-93717.
  • While no operability or significant concerns were identified, the licensee identified that two portable pumps credited in the flood analysis did not have periodic testing performed, and that flood barriers and penetrations that were not part of the fire protection program were not routinely inspected. These and several other minor deficiencies were entered into the CAP and the associated condition reports are listed in the Attachment to this report.

Braidwood
NRC Inspection Report
Issues Cited:

  • The inspectors identified that the licensee would have encountered several unplanned challenges in implementing various B.5.b mitigating strategies. These issues were identified by both the inspectors and by the licensee. These challenges include several examples in which prior opportunities for identification by the licensee existed. For example, the starting of the B.5.b pump was delayed after an issue with a support system required to start the pump was identified (IR 118926). Other delays identified by the licensee and/or the inspectors included: Flanges required to support B.5.b strategies were made of steel and were very heavy, making transport and installation of the equipment difficult with the resources that may be available (IR 1190517); Difficulty in obtaining access to a fire protection valve needed to implement B.5.b strategies due to the specific location (IR 1190203); Miscellaneous B.5.b equipment was not labeled (IR 1195986, IR 1190292); A weld must be removed to open a hatch to gain access to a refueling water storage tank (RWST) area used to implement B.5.b strategies (IR 1190588).

Browns Ferry
NRC Inspection Report
Issues Cited:

  • The inspectors determined that the licensee did not adequately verify the station’s capability to mitigate Station Blackout conditions. The AOI that governs response to an Station Blackout was not completely walked down, and therefore, was not demonstrated to be executable. Specifically, control room operator actions were not walked down.
  • However, the inspectors identified two longstanding licensee identified issues associated with Station Blackout mitigation capabilities that have not been completely resolved to date. These issues were associated with installed plant equipment involving safety related Emergency Diesel Generators (EDG) and the non-safety related 4KV Bus-Tie Board. The EDG parallel function has never been fully tested with two Residual Heat Removal (RHR) pumps loaded onto the same bus supplied from two paralleled Emergency Diesel Generators. The licensee’s design basis LOCA (Loss of Coolant Accident) with a concurrent LOOP (Loss of Offsite Power) required the onsite electrical system to be capable of powering two RHR subsystems (two RHR and two RHR Service Water pumps) on each unit, which per the licensee’s loss of offsite power and SBO procedure, required paralleling the Unit 1/2 and Unit 3 DGs for long term suppression pool cooling.

Brunswick
NRC Inspection Report
Issues Cited:

  • Inspectors also noted that the B.5.b equipment is stored in areas that would be affected by non-B.5.b scenarios. This would reduce its effectiveness in a severe natural phenomenon scenario, such as hurricane or flooding. Although this is in accordance with B.5.b guidelines, it is not reasonable to assume that the equipment would be available in a severe weather event.
  • Diesel fire pump batteries and 4kV breaker control box for the electric fire pump would be under water during a design basis external flooding event. Both of these pumps are located at ground level in the makeup water treatment building. This building is not seismically qualified or safety related. While designed according to existing requirements, this equipment would be adversely affected by a severe natural phenomenon. The licensee is assessing an improvement to this equipment through their corrective action program.

Byron
NRC Inspection Report
Issues Cited:

  • The flood barrier surveillance procedure did not require that heavy floor plugs be removed periodically to check the condition of their seals. A concern with the condition of the plug seals had been previously identified by the NRC inspectors in the spring of 2007 and in response the licensee had enhanced their flood seal inspections to add a requirement that when a floor plug was removed that flood seal be inspected. Additional enhancements were being considered by the licensee.

Callaway
NRC Inspection Report
Issues Cited:

  • The inspectors noted that the potential source of flooding identified for Rooms 5201 and 5203, emergency diesel generator rooms, was nonconservative in that it: Used a pressure lower than the system design pressure for the postulated break in the essential service water system. Credited installed sump pumps when a credible single source of power loss would have affected both pumps. A reanalysis confirmed that the resulting flood height with no sump pumps was acceptable. These issues were entered into the corrective action program as Callaway Action Request 201102691. The inspectors also identified that the licensee had not updated the internal flooding analysis for Room 3101, essential service water pipe chase, following a planned modification to the essential service water supply and return headers. Specifically, the licensee’s installation of high density polyethylene piping created a potential flooding source in excess of that currently analyzed in the Callaway licensing basis.
  • Also, the scenario posed revealed that the fire pumper truck did not have sufficient lengths of suction hose to reach the alternate water sources specified in the licensee procedure. Additional suction hose was located elsewhere in a procedurally unspecified locker after the inspectors' question. The procedure required a strainer for the suction hose that was not on the truck.

Calvert Cliffs
NRC Inspection Report
Issues Cited:

  • The inspector identified that the acceptance criteria for the timed start of the Station Blackout diesel was non-conservative. A timed start of the SBO is performed every 24 months to verify that the SBO diesel can be started and loaded within one hour of an SBO condition. The inspector determined that the acceptance criteria did not take into account the time for operators to complete steps in Emergency Operating Procedure (EOP)-O, "Post-Trip Immediate Actions." In the event of a Station Blackout, operators would perform steps in EOP-0 prior to transitioning to the EOP-7, "Station Blackout," which would be used to start and load the SBO diesel. The licensee initiated action to evaluate and correct the acceptance criteria. The inspector determined that the issue is minor because even with the adjustment to the acceptance criteria, the licensee can still meet the SBO rule requirements to start and load the SBO diesel within one hour of an SBO condition.

Catawba
NRC Inspection Report
Issues Cited:

  • Foam penetration seals in the auxiliary feedwater pump rooms and the diesel room roofs were not coated with sealant per the licensee’s design specification. The licensee wrote Work Orders to apply sealant to the foam.• The auxiliary feedwater room penetration seals were not included in the licensee’s internal flooding design basis document and were inspected as part of the existing seal inspection PM. Additional inspection PMs were created for inspection of conduit manhole flood seals and the diesel generator roof hatch covers. The licensee noted that two limited areas of the cooling tower yard berms designed to direct precipitation runoff away from the power block were degraded and required repair. Additionally, two jersey barriers were identified near the low pressure service water intake structure that could potentially affect runoff and were removed. The inspectors noted several cooling tower yard catch basins were partially blocked by rocks, silt and vegetation growth. Additional minor issues were identified relating to degraded trench cover sealant and flood barrier/door labeling.

Clinton
NRC Inspection Report
Issues Cited:

  • Material condition of the diesel-driven horizontal fire pump was generally poor and the licensee has not focused appropriate attention to maintaining the pump. During a test run observed by the inspectors on April 6, 2011, the pump’s inboard and outboard shaft packing glands overheated and failed. The operator had to shut down the pump early during the test run. ARs 01198618 and 01203214 were written to address the pump shaft packing problem. During the past year, there have been several material condition issues identified by the licensee affecting the horizontal fire pump including problems with the pump shaft packing glands, bearings, battery, and battery charger. No specific commitments were found during this review for the licensee to maintain this pump to implement the strategies associated with B.5.b and 10 CFR 50.54(hh).
  • Adequate training is lacking for implementation of CPS 4303.01, “Extensive Damage Mitigation Guide,” and CPS 4303.01P018, “ERO Activation During Extreme Damage Event,” to enable non-licensed plant staff (e.g., non-licensed operators and security staff) on shift to initiate communications and activate the ERO in accordance with the procedures. In particular, non-licensed operators and security staff were unfamiliar with these procedures and have had no specific training on them.
  • AR 01197979 was written to identify that most flood penetration seals were not routinely inspected. No preventive maintenance program or procedural acceptance criteria existed. The licensee completed walk downs of plant areas with flood penetration seals and observed accessible seals. The licensee’s long term resolution will be to develop a preventive maintenance program to inspect seals on a periodic basis.

Columbia Generating Station
NRC Inspection Report
Issues Cited: None significant.

Comanche Peak
NRC Inspection Report
Issues Cited:

  • The inspectors observed that some suction hoses listed in the extreme damage mitigation procedure for the accident mitigation equipment pump were not in the designated location or were absent. The equipment in the procedure did not match the operations inventory that the licensee used to walk down the equipment. This observation was documented in Condition Report CR-2011-004919. The licensee currently plans to add suction hoses or revise the procedure as necessary. The inspectors plan to conduct further inspection and document the results in NRC Inspection Report 2011003. The inspectors also observed that some electrical equipment used in the extreme damage mitigation alternate instrument power and indication was absent, however, identical equipment was available in a different location that was proceduralized.
  • The inspectors observed that the lube oil storage building is a potential fire/explosion hazard and is located near the accident mitigation equipment sea-land trailer. The licensee documented this observation in Condition Report CR-2011-005399. The inspectors also observed that the alternate service water pumps were located in a non-seismic building. The licensee documented this observation in Condition Report CR-2011-005615. In addition, the inspectors observed that the licensee has never tested the fire truck pumping from the reservoir.

Cooper
NRC Inspection Report
Issues Cited:

  • The licensee has an issue documented in Inspection Report 05000298/2010006, "Cooper Nuclear Station - NRC Triennial Fire Protection Inspection Report," Dated March 17, 2011, that is relevant to this inspection scope: An apparent violation of 10 CFR Part 50, Appendix B, Criterion V, "Instructions, Procedures, and Drawings," and Criterion XVI, "Corrective Action," with a preliminary white significance, was identified for the licensee’s failure to ensure that some steps contained in emergency procedures at Cooper Nuclear Station would work as written and the concurrent failure to assure that a condition adverse to quality was promptly identified and corrected.
  • The licensee identified a potential vulnerability associated with its ability to position various contingency components during a site-wide flood. For example, the licensee’s ability to put in place the portable fire pump or portable diesel generator would be challenged with the river at probable maximum flood levels. The licensee identified that the diesel fire pump batteries could be impacted during a probable maximum flood. The administration building houses the technical support center and the operations support center but receives no flooding barriers per current side procedures. The flooding of this building could hamper the execution of the emergency plan following a safe shutdown earthquake concurrent with a probable maximum flood event. All of these issues have been entered into the station corrective action program for resolution.

Crystal River
NRC Inspection Report
Issues Cited:

  • The licensee identified that some as-found raw water and circulating water encapsulation sleeve gap tolerances were too large and exceeded the design requirements. As a result of the larger gaps, a greater leak flow rate into the auxiliary building would cause the flood rate to increase. This in turn could challenge the 30-minute period that is credited for operators to take action to stop the leak into the auxiliary building.

Davis Besse
NRC Inspection Report
Issues Cited:

  • In one instance, however, the inspectors identified a discrepancy with the necessary equipment staged to perform the actions to start an Emergency Diesel Generator (EDG) without normal station direct current (dc) power available. Specifically, Attachment 8 of DB-OP-02600, “Operational Contingency Response Action Plan,” requires a total of 11 prepared 8 gauge insulated wires. Nine wires are used to connect 10 emergency batteries in series, and 2 longer lead wires are provided to connect positive and negative sides of the series batteries to the EDG panel. When the batteries are connected they are able to produce an approximate 60 volts direct current (Vdc) supply used to provide excitation needed for field flash of the EDG. During a walkdown of the required inventory, the inspectors only found a total of 10 wires staged and available. One longer lead wire was missing from the bundle.
  • During their CAP review, however, the licensee noted that a previously identified condition documented in CR 10-79719 had not yet been fully corrected. That condition, a reduction in the Station Blackout diesel generator’s cooling capacity, presently limits SBO diesel generator availability such that the Station Blackout diesel generator must be declared unavailable whenever outside ambient air temperature exceeds 95 degrees F. Corrective actions planned by the licensee include cleaning and inspection of the Station Blackout diesel generator radiator tubes. The licensee initiated CR 11-91648 to capture this issue in their CAP.

DC Cook
NRC Inspection Report
Issues Cited:

  • The licensee identified during material staging walk downs that hoses for aligning demineralized water to the spent fuel pool during a loss of inventory needed to be designated and staged in closer proximity to the spent fuel pool. Additionally, the licensee identified that specified materials required to repair or reduce spent fuel pool leakage are currently stored off site and need to be stored on site. The inspectors verified these conditions were entered into the licensee’s corrective action program.

Diablo Canyon
NRC Ins

This article is part of an ongoing investigation:
Nuclear Safety

Nuclear Safety

With the disaster in Japan, we're investigating questions about nuclear safety.

The Story So Far

Following a massive earthquake and tsunami in Japan, hydrogen explosions rocked three reactors at the Fukushima Daiichi nuclear power plant. Radioactive spent fuel stored in pools was also affected, especially at one reactor—the plant has a total of six—where multiple fires erupted. Evacuation orders were issued, potassium iodine tablets distributed, and plant employees used seawater and external electrical power to cool the stricken reactors, three of which had a partial core meltdown.

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