TMI-2: 1980 - The Susquehanna Valley Alliance, based in Lancaster, successfully prevented GPU/Met Ed from dumping 700,000 gallons of radioactive water into the Susquehanna River.
TMI-1: August 14, 1985 - Three-thousand gallons of LLRW water leaked into the containment building.
TMI-2: February 1986 - One celled organisms believed to be fungus, bacteria and algae like creatures were discovered. These creatures obscured the view of the reactor core, and impeded the cleanup.
TMI-2: May 23, 1988 - A clean up worker "fell part-way into an opening above the Unit 2 reactor vessel" and "received low radiation exposure to the skin below the knees." During the incident the "worker's legs were immersed in shielding water above the reactor vessel up to his knees.
TMI-2: December 1990 - Despite legal objections, GPU began evaporating 2.3 million gallons of accident-generated radioactive water (AGW). The evaporator was shut down two days after operations commenced due to mechanical problems.
TMI-2: January 1991 - The evaporator was shut down four times due to electrical and mechanical "difficulties."
TMI-2: February 1991 - An operator "inadvertently flooded the vaporizer" and several days later an operator was discovered "apparently sleeping."
TMI-2: March, 1991 - A "small quantity of accident generated water was vaporized" without being processed.
TMI-2: April-May 1991 - The evaporator was shut down for most of this period so GPU could "rewrite the main operating procedure." The Nuclear Regulatory Commission (NRC) issued a Notice of Violation related to evaporator operations
TMI-2: June, 1991 - The NRC noted repeated mispositioning of an AGW valve. The valve in question was also involved in the NRC's Notice of Violation issued in April.
TMI-2: February 1992 - The evaporator was shut down again due to the failure of the blender-dryer. Replacement of the blender was delayed until August.
TMI-2: May 1992 - GPU decided to use a "temporary" blender-dryer until a permanent replacement was installed in August.
TMI-2: August 5, 1992 - GPU "declared an event of potential public interest when the Unit-2 west cooling tower caught fire." The fire lasted for ten minutes.
TMI-2: August-September 1992 - Some of the water in the evaporator's borated water storage tank was "processed" twice due to "slightly higher activity levels."
TMI-2: November 1992 - Approximately 600,000 gallons of AGW was processed twice due to "slightly higher activity levels."
TMI-1: March 5, 1993 - The NRC issued a Notice of Violation "related to an event which resulted when an Auxiliary Operator (AO) bypassed river water from both Decay Heat Service Coolers (DC-C -2A/B) affecting both trains of the Decay Heat Closed Cooling Water System" (GPU Nuclear response to NOV, August 17, 1993.
TMI-1: September 15, 1993 - During surveillance testing, "250 gallons of water leaked from the 'C' makeup pump casing drain valve, MU-V-172C, because the valve had been inadvertently left open approximately 1.5 turns." (IR 50-289/93-22.)
TMI-1: September 22, 1993 - During a 90 minute interval, "4,600 gallons of water were inadvertently transferred from the reclaimed water storage tank to the Reactor Building sump...Maintenance personnel had opened the reclaimed water supply valve, CA-V-194, to the reactor coolant drain (RCDT) which in turn overflowed to the Reactor Building sump via the opening from the RCDT relief valve. Operators were not alerted to the rising level in the RCDT, because the level instrumentation and high level alarm were out of service." (IR 50-289/93-22.)
TMI-1: September 24, 1993 - "[D]ue to a level difference, about 4000 gallons of water were inadvertently transferred from the fuel transfer canal to the pressurizer..." (IR 50-289/93-22.)
TMI-2: November 2, 1993 - In a letter to the NRC, GPU Nuclear acknowledged: "During the TMI-2 accident, the cork seam located in the Auxiliary Building Seal Injection Valve Room (SIVR) was contaminated with radioactive water. Attempts to contain the contamination within the room have been unsuccessful. During the past 14 years, radioactive material has spread along the joint in one direction into the Annuls, and in the other direction into the Auxiliary Building, Service Building and Control Building West (R. L. Long, GPU Nuclear, Director, Services Division/TMI-2.)"
TMI-2: August, 1993 - Evaporation of 2.3 million gallons of AGW was completed over six months behind schedule. The evaporator will be disassembled and removed from the site by October, 1993.
TMI-1: October 8, 1993 - "[W]hile filling the 'A' condensate storage tank (CST) from the million gallon tank, 300 to 400 gallons of water spilled through the CST vent." (IR 50-289/93-22.)
TMI-2: October 28, 1993 - According to the Pennsylvania Department of Environmental Resources, the total activity during evaporation was 658 curies of tritium or 1 to 1.3 MR dose to the public.
TMI-2: November 2, 1993 - In a letter to the NRC, GPU Nuclear acknowledged: "During the TMI-2 accident, the cork seam located in the Auxiliary Building Seal Injection Valve Room (SIVR) was contaminated with radioactive water. Attempts to contain the contamination within the room have been unsuccessful. During the past 14 years, radioactive material has spread along the joint in one direction into the Annuls, and in the other direction into the Auxiliary Building, Service Building and Control Building West (R. L. Long, GPU Nuclear, Director, Services Division/TMI-2.)"
TMI-2: December, 1993 - GPU placed TMI-2 in Post-Defueling Monitored Storage.
TMI-1: February 23, 1994 - GPU "determined that the spline adapters were installed upside down [for the nuclear river water motor operated valves.]" (IR 50-289/94-13.)
TMI-1: May 23, 1994 - An auxiliary operator inadvertently reduced the level deferential in the sodium hydroxide tank/borated water storage tank. The incident prompted a Licensee Event Report.
TMI-1: July 12, 1994 - A through wall leak was discovered in a safety related nuclear service river water pipe.
TMI-1: September 16, 1994 - Power was reduced to 50% to test problems associated with the condenser. "Small leaks in tubes inside the condenser are allowing river water used for cooling to mix with pure water of the steam system" (GPU Nuclear, "News Release," September 15, 1994.)
TMI-1: December 3, 1994 - Power was reduced to 50% to repair a "water leak", i.e. repair main condenser tube leaks. In addition, 145 of the the condenser's 66,000 tubes were "removed."
TMI-1: March 8, 1995 - Radioactive water leaked and contaminated a worker. An Unusual Event was declared.
TMI-1: August 17, 1995 - "A weakness was noted in the plant response to the degraded condition of the safety related 'B' nuclear river (NR) water pump discharge check valve NR-V-20B. The check valve was declared inoperable after the plant operators noticed the 'B' NR pump rotating backwards on two separate occasions. When the problem was first noted on June 10, 1995, the check valve condition, pump performance, and understanding of the pump discharge MOV operation were not evaluated thoroughly to ensure that the NR system was performing acceptably. The performance of the pump inservice surveillance test on June 28, 1995, revealed that the condition of the check valve was degraded." (Jacques P. Durr, Chief, Projects branch No. 4, Division of Reactor Projects, NRC.)
TMI-1: October 10, 1995 - "A number of issues have occurred that raise concern regarding the adequacy of your planning process for maintenance activities. Examples of these include, maintenance on instrument line fittings which resulted in a reactor coolant system leak ...and a weak initial response to the degraded condition of the nuclear river discharge check valve that resulted in a delay in identifying the degraded condition of the nuclear river water system. Richard W. Cooper, Division of Reactor Projects, NRC.)
TMI-1: December 4, 1995 - The NRC identified an "area of concern" relating to "a clogged strainer for a decay river pump. Considering the potential generic concern with the other safety related river water pumps, it appears that a more timely approach was warranted to ensure the operability of the non-running pumps." (See August 10, 1995 for a related incident.)
TMI-1: December 21, 1996 - GPU reported that the reactor was "outside the design basis", due to concerns caused by a recent evaluation of the borated water switch over tank. (Event, 31497.) (See August, 1999, for follow-up report.)
TMI-1: April 25, 1997 - An apparent violation associated with Technical Specification was identified, and "A predecisional enforcement conference to discuss these apparent violations has been scheduled for May 22, 1997."
The NRC identifed design control weaknesses in the performance of calculations and in the control of calculations used in the analysis for switch over to decay heat removal system (DHRS) pump suction from the borated water storage tank (BWST) to the reactor building sump under post-accident conditions
TMI-1: July 28, 1997 - GPU "declared the 'B' train of low pressure injection and building spray inoperable because these systems are affected by the transfer from the borated water storage tank to the reactor building sump. This places the unit in a 72-hour technical specification limiting condition for operation." [Event date: July 25, 1997.] (NRC Region I, IHQ OPS Officer, Leigh Trocine.)
TMI-1: October 15, 1997 - GPU failed to implement operating procedures during the filling and venting of the reactor coolant system (RCS). "Consequently, approximately 50 gallons of RCS water overflowed out of the CRDM [control rod drive mechanism] vents onto the reactor vessel head area." (NRC 50-289/97-09 [EA 97-433 & 50-289/97-10).
The NRC issued a Notice of Violation.
TMI-2: June 4, 1998 - "GPUN found several pipes penetrating the wall between the turbine building basement and the control building in Unit-2 to be open on both sides of the wall. This condition was contrary to the Unit-2 post-defueling monitored storage safety analysis report (PDMS-SAR) which requires entrances to the control building area to be watertight or provided with flood panels and openings that are potential leak baths to be sealed." (IR 50-289/98-08.)
TMI-2: July 2, 1998 - An LER was necessary due to the breaching of flood barriers "between the turbine building and the control building area due to inadequate fieldwork documents." (IR 50-289/98-08.)
TMI-1: June 23, 1999 - "Three Mile Island, trying to rid itself of clams, recently released too much of a potentially hazardous chemical into the Susquehanna River ...State regulations allow TMI to release 0.3 parts per million of Clamtrol back into the Susquehanna River. For about an hour, the plant was releasing 10,500 gallons per minute containing twice the amount." (York Daily Record, July 7, 1999.)
TMI-1: July 6, 1999 - "The feed tank to the miscellaneous waste evaporator was overfilled resulting in a spill of contaminated water in the miscellaneous waste evaporator room." (NRC, IR 50-289/99-04.)
TMI-1: February 2, 2000 - The "operating crew" improperly implemented a controlled draining of the borated water storage tank (BWST).
TMI-1: August 24, 2001 - The NRC identified two Non-Cited Violations "of very low safety significance". One NCV dealt with improper "design assumptions...for cross connecting the safety related NR [Nuclear Services River Water] and non-safety related SR [Secondary River Water], on a total loss of SR." The other NCV related to an inadequate pump surveillance acceptance standards for the DH river water pumps... This issue was considered to be more than minor because the lack of proper acceptance criteria in surveillance procedure 1300-3D had a credible impact on safety." (IR 50-0289/01-010).
TMI-1: April 16, 2002 - The following issue was reviewed by the NRC: "[U]nanticipated reactor coolant system (RCS) letdown isolation." (IR 50-289/02-05).
Also a "Green" cornerstone event was identified regarding the inoperability of instrumentation that would have "precluded the operation of traveling screens in fast speed, which could have impacted the reliability of the screen river debris removal function." (See May 30, 2002, for a related event.)
TMI-1: May 30, 2002 - "The emergency feedwater system was potentially impacted ...while an anomaly was investigated...The configuration of the safety-related river water systems was altered for the bi-annual clam treatment in June 2002. The inspectors verified...that operating parameters were normal." (IR 50-289/02-05). (See April 16, 2002, for a related event.)
TMI-1: March 22, 2003* - The NRC issued a Green Non-Cited Violation after "inspectors found AmerGen failed to adequately control the use of a temporary floor drain plug used to function as a flood barrier. The inspectors found the plug deflated and longer capable of functioning as a flood barrier. The finding is greater than minor because, in the event of a maximum probable flood, the operability of the safety-related equipment the river water pump house would have been challenged"(IR 05000289/2003003).
* Please note that AmerGen replaced 'C' nuclear river water pump on March 3, 2003 .
(IR 50-289/03-02) (For more information on "River Water problems", please refer to: (March 3 and August 17, 1993; February 23, March 30, July 12 and September 16, 1994; October 9 and December 4, 1995; September 29, 1996; November 20, 1997; and, August 24, 2001.)