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86-525: On December 6, 1971, Houston Lighting & Power Co. (HL&P), the City of Austin , the City of San Antonio , and the Central Power and Light Co. (CPL) initiated a feasibility study of constructing a jointly-owned nuclear plant. The initial cost estimate for the plant was $ 974 million (equivalent to approximately $ 5,700,741,167 in 2015 dollars). By mid-1973, HL&P and CPL had chosen Bay City as

172-503: A LOC incident. However, when a team was sent to investigate the status of the RCIC of unit 2 the following morning (02:55), they confirmed that the RCIC was operating with the PCV pressure well below design limits. Based on this information, efforts were focused on unit 1. However, the condensate storage tank from which the RCIC draws water was nearly depleted by the early morning, and so the RCIC

258-494: A Nuclear Regulatory Commission report , the low steam generator levels were due to loss of feedwater pumps 11 and 13. However, Unit 2 and both units at the Comanche Peak Nuclear Power Plant remained online during the power outage. South Texas Project Electric Generating Station generated 21,920 GWh in 2022. Nuclear whistleblower Ronald J. Goldstein was a supervisor employed by EBASCO , which

344-445: A causal relationship between radiation and the cancer. Six other persons have been reported as having developed cancer or leukemia . Two workers were hospitalized because of radiation burns , and several other people sustained physical injuries as a consequence of the accident. Criticisms have been made about the public perception of radiological hazards resulting from accidents and the implementation of evacuations (similar to

430-403: A closed coolant loop from the pressure vessel with a heat exchanger in a dedicated condenser tank. Steam would be forced into the heat exchanger by the reactor pressure, and the condensed coolant would be fed back into the vessel by gravity. Each reactor was initially designed to be equipped with two redundant ICs which were each capable of cooling the reactor for at least 8 hours (at which point,

516-405: A closed-loop system which draws coolant from the suppression chamber (SC) instead of the storage tank, should the storage tank be depleted. Although this system could function autonomously without an external energy source (besides the steam from the reactor), direct current (DC) was needed to remotely control it and receive parameters and indications and alternating current (AC) was required to power

602-432: A plume exposure pathway zone with a radius of 10 miles (16 km), concerned primarily with exposure to, and inhalation of, airborne radioactive contamination, and an ingestion pathway zone of about 50 miles (80 km), concerned primarily with ingestion of food and liquid contaminated by radioactivity. In 2010, the population within 50 miles (80 km) of the station was 254,049, an increase of 10.2 percent since 2000;

688-499: A service area of 5,000 square miles (13,000 km ). In 1998 in terms of kilowatt-hour sales it was the tenth-largest energy company in the United States. It began operations in 1882. In 1999 Houston Industries changed its name to Reliant Energy. Therefore HL&P was renamed Reliant Energy HL&P/Entex . When the state of Texas deregulated the electricity market , HL&P was split into several companies. In 2003

774-494: A substantial impact on the nuclear industry including STNP. The new team again moved forward with developing a new budget and schedule. Brown and Root revised their completion schedule to June 1989 and the cost estimate to $ 4.4–$ 4.8 billion. HL&P executives consulted with its own project manager and concluded that Brown and Root was not making satisfactory progress and a decision was reached to terminate their role as architect/engineer but retain them as constructor. Brown and Root

860-758: The CenterPoint Energy Plaza in Downtown Houston . The Bob Lanier Public Works Building in Downtown Houston, formerly the Electric Building, was previously the HL&;P office building. In 1999 the City of Houston, which had acquired the building, renovated it for $ 43 million to house city government offices. Fukushima nuclear accident The Fukushima nuclear accident was a major nuclear accident at

946-480: The Fukushima Daiichi nuclear power plant in Ōkuma, Fukushima , Japan which began on 11 March 2011. The proximate cause of the accident was the 2011 Tōhoku earthquake and tsunami , which resulted in electrical grid failure and damaged nearly all of the power plant's backup energy sources . The subsequent inability to sufficiently cool reactors after shutdown compromised containment and resulted in

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1032-476: The disposal of treated wastewater once used to cool the reactor , resulting in numerous protests in neighboring countries. The Fukushima Daiichi Nuclear Power Plant consisted of six General Electric (GE) light water boiling water reactors (BWRs). Unit 1 was a GE type 3 BWR. Units 2–5 were type 4. Unit 6 was a type 5. At the time of the Tōhoku earthquake on 11 March 2011 , units 1–3 were operating. However,

1118-456: The reactor pressure vessel (RPV) and embedded itself into the concrete at the base of the PCV. Although at the time it was difficult to determine how far the fuel had eroded and diffused into the concrete, it was estimated that the fuel remained within the PCV. Computer simulations, from 2013, suggest "the melted fuel in Unit 1, whose core damage was the most extensive, has breached the bottom of

1204-500: The spent fuel pools of all units still required cooling. Many of the internal components and fuel assembly cladding are made from a zirconium alloy (Zircaloy) for its low neutron cross section . At normal operating temperatures (~300 °C (572 °F)), it is inert. However, above 1,200 °C (2,190 °F), Zircaloy can be oxidized by steam to form hydrogen gas or by uranium dioxide to form uranium metal . Both of these reactions are exothermic . In combination with

1290-492: The 13 EDGs, 10 were water-cooled and placed in the basements about 7–8 m below the ground level. The coolant water for the EDGs was carried by several seawater pumps placed on the shoreline which also provide water for the main condenser. These components were unhoused and only protected by the seawall. The other three EDGs were air-cooled and were connected to units 2, 4, and 6. The air-cooled EDGs for units 2 and 4 were placed on

1376-573: The 20th. Unit 6 was not operating, and its decay heat was low. All but one EDG was disabled by the tsunami, allowing unit 6 to retain AC-powered safety functions throughout the incident. However, because the RHR was damaged, workers activated the make-up water condensate system to maintain the reactor water level until the RHR was restored on the 20th. Cold shutdown was achieved on the 20th, less than an hour after unit 5. On 21 March, temperatures in

1462-567: The Chernobyl nuclear accident), as they were accused of causing more harm than they prevented. Following the accident, at least 164,000 residents of the surrounding area were permanently or temporarily displaced (either voluntarily or by evacuation order). The displacements resulted in at least 51 deaths as well as stress and fear of radiological hazards. Investigations faulted lapses in safety and oversight, namely failures in risk assessment and evacuation planning. Controversy surrounds

1548-462: The FP injection port was hidden under debris. The next morning (12 March, 04:00), approximately 12 hours after the loss of power, freshwater injection into the reactor vessel began, later replaced by a water line at 09:15 leading directly from the water storage tank to the injection port to allow for continuous operation (the fire engine had to be periodically refilled). This continued into the afternoon until

1634-487: The Fukushima coast. In response to the station blackout during the initial hours of the accident and the ongoing uncertainty regarding the cooling status of units 1 and 2, a 2 km radius evacuation of 1,900 residents was ordered at 20:50. However, due to difficulty coordinating with the national government, a 3 km evacuation order of ~6,000 residents and a 10 km shelter-in-place order for 45,000 residents

1720-523: The HPCI and RCIC systems, but both failed to restart. Following this loss of cooling, workers established a water line from the valve pit to inject seawater into the reactor alongside unit 2. However, water could not be injected due to RPV pressures exceeding the pump capability. Similarly, preparations were also made to vent the unit 3 PCV, but PCV pressure was not sufficient to burst the rupture disk. Later that morning (9:08), workers were able to depressurize

1806-539: The HPCI system showed signs of malfunction. The HPCI isolation valve failed to activate automatically upon achieving a certain pressure. In response, the workers switched off HPCI and began injection of water via the lower-pressure firefighting equipment. However, the workers found that the SRVs did not operate to relieve pressure from the reactor vessel to allow water injection by the DDFP. In response, workers attempted to restart

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1892-707: The International Nuclear Event Scale. According to the United Nations Scientific Committee on the Effects of Atomic Radiation , "no adverse health effects among Fukushima residents have been documented that are directly attributable to radiation exposure from the Fukushima Daiichi nuclear plant accident". Insurance compensation was paid for one death from lung cancer , but this does not prove

1978-435: The PCV was completed later that afternoon at 14:00. At the same time, pressure in the reactor vessel had been decreasing to equalize with the PCV, and the workers prepared to inject water into the reactor vessel using the DDFP once the pressure had decreased below the 0.8 MPa limit. Unfortunately, the DDFP was found to be inoperable and a fire truck had to be connected to the FP system. This process took about 4 hours, as

2064-473: The RCIC system failed. In response, the high-pressure coolant injection (HPCI) system was activated to alleviate the lack of cooling while workers continued to attempt to restart the RCIC. Additionally, the FP system was used to spray the PCV (mainly the SC) with water in order to slow the climbing temperatures and pressures of the PCV. On the morning of the 13th (02:42), after DC power was restored by new batteries,

2150-422: The RCIC system was continuing to cool the reactor. However, knowing that their DC supply was limited, the workers managed to extend the backup DC supply to about 2 days by disconnecting nonessential equipment, until replacement batteries were brought from a neighboring power station on the morning of the 13th (with 7 hours between loss and restoration of DC power). At 11:36 the next day, after 20.5 hours of operation,

2236-702: The South Texas Nuclear Project site. South Texas Nuclear Project Partners CPS Energy and Austin Energy were not involved in the initial letter of intent and development plans. On September 24, 2007, NRG Energy filed an application with the NRC to build two Toshiba ABWRs at the South Texas Nuclear Project site. It was the first application for a nuclear reactor submitted to the NRC since 1979. The proposed expansion would generate an additional 2700 MW of electrical generating capacity, which would double

2322-499: The United States Department of Energy. On 19 April 2011, NRG announced in a conference call with shareholders, that they had decided to abandon the permitting process on the two new units due to the ongoing expense of planning and slow permitting process. Anti-nuclear campaigners alleged that the financial situation of new partner TEPCO, combined with the ongoing Fukushima nuclear accident were also key factors in

2408-436: The atmosphere, those which remain in a gaseous phase will simply be diluted by the atmosphere, but some which precipitate will eventually settle on land or in the ocean. Approximately 40–80% of the atmospheric caesium-137 was deposited in the ocean. Thus, the majority (90~99%) of the radionuclides which are deposited are isotopes of iodine and caesium, with a small portion of tellurium , which are almost fully vaporized out of

2494-410: The blackout, the RCIC was functioning as designed without the need for operator intervention. The safety relief valves (SRVs) would intermittently release steam directly into the PCV suppression torus at its design pressure and the RCIC properly replenished lost coolant. However, following the total blackout of Unit 2, the plant operators (similar to Unit 1) assumed the worst-case scenario and prepared for

2580-504: The capacity of the site. The total estimated cost of constructing the two reactors is $ 10 billion, or $ 13 billion with financing, according to Steve Bartley, interim general manager at CPS Energy. In October 2009, main contractor Toshiba had informed CPS Energy that the cost would be "substantially greater," possibly up to $ 4 billion more. As a result of the escalating cost estimates for units 3 and 4, in 2010 CPS Energy reached an agreement with NRG Energy to reduce CPS's stake in

2666-493: The company was split into Reliant Energy , Texas Genco , and CenterPoint Energy . Texas Genco assumed control of the area's power plants. CenterPoint assumed control of the poles and power lines. Reliant Energy took over the sales of electricity to businesses and individuals. Before the dissolution of the company, its headquarters were shared with Houston Industries in the Houston Industries Plaza, now

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2752-459: The condenser tank would have to be refilled). However, it was possible for the IC system to cool the reactor too rapidly shortly after shutdown which could result in undesirable thermal stress on the containment structures. To avoid this, the protocol called for reactor operators to manually open and close the condenser loop using electrically operated control valves. After the construction of Unit 1,

2838-708: The contaminated waters far into the Pacific Ocean, dispersing the radioactivity. As of late 2011, measurements of both the seawater and the coastal sediments suggested that the consequences for marine life would be minor. Significant pollution along the coast near the plant might persist, because of the continuing arrival of radioactive material transported to the sea by surface water crossing contaminated soil. The possible presence of other radioactive substances, such as strontium-90 or plutonium , had not been sufficiently studied. Recent measurements show persistent contamination of some marine species (mostly fish) caught along

2924-431: The core due to their high vapor pressure. The remaining fraction of deposited radionuclides are of less volatile elements such as barium , antimony , and niobium , of which less than a percent is evaporated from the fuel. In addition to atmospheric deposition, there was also a significant quantity of direct releases into groundwater (and eventually the ocean) through leaks of coolant which had been in direct contact with

3010-399: The critical parts of the reactor was found. In 2006, the design of the reactors was reevaluated with new standards requiring the reactors to withstand accelerations ranging up to 450 Gal. In the event of an emergency, operators planned to pump water into the reactors to keep them cool. This would inevitably create steam which should not be very radioactive because the fuel would still be in

3096-534: The decision. NRG has written off its investment of $ 331 million in the project. Despite the April 2011 NRG announcement of the reactor's cancellation, the NRC continued the combined licensing process for the new reactors in October 2011. It was unclear at the time why the reactor license application was proceeding. During early 2015 some pre-construction activities were performed on site and initial NRC documents listed

3182-473: The exothermic reaction of boron carbide with stainless steel , these reactions can contribute to the overheating of a reactor. In the event of an emergency, reactor pressure vessels (RPV) are automatically isolated from the turbines and main condenser and are instead switched to a secondary condenser system which is designed to cool the reactor without the need for pumps powered by external power or generators. The isolation condenser (IC) system involved

3268-443: The explosion. The debris produced by the explosion damaged the mobile emergency power generator and the seawater injection lines. The seawater injection lines were repaired and put back into operation at 19:04 until the valve pit was nearly depleted of seawater at 01:10 on the 14th. The seawater injection was temporarily stopped in order to refill the valve pit with seawater using a variety of emergency service and JSDF vehicles. However,

3354-582: The federal nuclear whistleblower law to provide protection for reports made to internal systems and prevent retaliation against whistleblowers. The STPEGS reactors are operated by the STP Nuclear Operating Company (STPNOC). Ownership is divided among Constellation Energy at 44 percent, San Antonio municipal utility CPS Energy at 40 percent and Austin Energy at 16 percent. The Nuclear Regulatory Commission defines two emergency planning zones around nuclear power plants:

3440-409: The final 20 km evacuation zone. 20% of residents who were within the initial 2 km radius had to evacuate more than six times. Additionally, a 30 km shelter in place order was communicated on the 15th, although some municipalities within this zone had already decided to evacuate their residents. This order was followed by a voluntary evacuation recommendation on the 25th, although

3526-400: The following numbers of fuel assemblies: The original design basis was a zero-point ground acceleration of 250 Gal and a static acceleration of 470 Gal, based on the 1952 Kern County earthquake (0.18 g , 1.4 m/s , 4.6 ft/s ). After the 1978 Miyagi earthquake , when the ground acceleration reached 0.125 g (1.22 m/s , 4.0 ft/s ) for 30 seconds, no damage to

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3612-475: The following units were designed with new open-cycle reactor core isolation cooling (RCIC) systems. This new system used the steam from the reactor vessel to drive a turbine which would power a pump to inject water into the pressure vessel from an external storage tank to maintain the water level in the reactor vessel and was designed to operate for at least 4 hours (until the depletion of coolant or mechanical failure). Additionally, this system could be converted into

3698-455: The freshwater tank was nearly depleted. In response, injection stopped at 14:53 and the injection of seawater, which had collected in a nearby valve pit (the only other source of water), began. Power was restored to units 1 (and 2) using a mobile generator at 15:30 on 12 March. At 15:36, a hydrogen explosion damaged the secondary confinement structure (the RB). The workers evacuated shortly after

3784-542: The fuel pond had risen slightly, to 61 °C (142 °F), and water was sprayed over the pool. Power was restored to cooling systems on 24 March and by 28 March, temperatures were reported down to 35 °C (95 °F). Quantities of the released material are expressed in terms of the three predominant products released: caesium-137 , iodine-131 , and xenon-133 . Estimates for atmospheric releases range from 7–20  PBq for Cs-137, 100–400 PBq for I-131, and 6,000–12,000 PBq for Xe-133. Once released into

3870-496: The fuel. Estimates for this release vary from 1 to 5.5 PBq caesium-137 and 10-20 PBq iodine-131 . According to the French Institute for Radiological Protection and Nuclear Safety , the release from the accident represents the most important individual oceanic emissions of artificial radioactivity ever observed. The Fukushima coast has one of the world's strongest currents ( Kuroshio Current ). It transported

3956-412: The ground floor of the spent fuel building, but the switches and various other components were located below, in the basement. The third air-cooled EDG was in a separate building placed inland and at higher elevations. Although these EDGs are intended to be used with their respective reactors, switchable interconnections between unit pairs (1 and 2, 3 and 4, and 5 and 6) allowed reactors to share EDGs should

4042-440: The ground or basement levels at approximately 15:41. The switching stations that provided power from the three EDGs located higher on the hillside also failed when the building that housed them flooded. One air-cooled EDG, that of unit 6, was unaffected by the flooding and continued to operate. The DC batteries for units 1, 2, and 4 were also inoperable shortly after flooding. As a result, units 1–5 lost AC power and DC power

4128-415: The isolation valves. In an emergency where backup on-site power was partially damaged or insufficient to last until a grid connection to off-site power could be restored, these cooling systems could no longer be relied upon to reliably cool the reactor. In such a case, the expected procedure was to vent both the reactor vessel and primary containment using electrically or pneumatically operated valves using

4214-437: The majority of residents had evacuated from the 30 km zone by then. The shelter in place order was lifted on April 22, but the evacuation recommendation remained. Of an estimated 2,220 patients and elderly who resided within hospitals and nursing homes within the 20 km evacuation zone, 51 fatalities are attributed to the evacuation. There was one suspected death due to radiation, as one person died 4 years later of

4300-455: The need arise. The power station was also equipped with backup DC batteries kept charged by AC power at all times, designed to be able to power the station for approximately 8 hours without EDGs. In units 1, 2, and 4, the batteries were located in the basements alongside the EDGs. In units 3, 5, and 6, the batteries were located in the turbine building where they were raised above ground level. The units and central storage facility contained

4386-601: The new units from 50% to 7.625%. To that point, CPS Energy had invested $ 370 million in the expanded plant. CPS Energy's withdrawal from the project put the expansion into jeopardy. In October 2010, the South Texas Project announced that the Tokyo Electric Power Company (TEPCO) had entered into an agreement with Nuclear Innovation North America (a joint venture between the reactor manufacturer, Toshiba, and plant partner NRG Energy) which

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4472-406: The ocean began two hours later, and cooling of unit 3 resumed in the afternoon (approximately 16:00) and continued until cooling was lost once more as a result of site evacuation on the 15th. Unit 4 was not fueled at the time, but the unit 4 spent fuel pool (SFP) contained a number of fuel rods. On 15 March, an explosion was observed at unit 4 RB during site evacuation. A team later returned to

4558-536: The original targeted commercial operational dates as March 2015 for unit 3 and a year later for the other unit. On February 9, 2016 the NRC approved the combined license. Due to market conditions, no construction events occurred at that time. The two planned units do not currently have a planned construction date. On February 15, 2021 during a major power outage that impacted much of the state of Texas, an automatic reactor trip shut South Texas Nuclear Generation Station Unit 1 due to low steam generator levels. According to

4644-562: The population within 10 miles (16 km) was 5,651, a 2.4 percent decrease. Cities within 50 miles include Lake Jackson (40 miles to the city center) and Bay City. The Nuclear Regulatory Commission's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at South Texas was 1 in 158,730, according to an NRC study published in August 2010. The South Texas Generating Station consists of two operational reactors. A two reactor expansion (Unit 3 and Unit 4)

4730-463: The power station to inspect unit 4, but were unable to do so due to the present radiological hazard. The explosion damaged the fourth-floor rooftop area of Unit 4, creating two large holes in a wall of the RB. The explosion was likely caused by hydrogen passing to unit 4 from unit 3 through shared pipes. The following day, on the 16th, an aerial inspection was performed by helicopter which confirmed there

4816-410: The primary containment vessel and even partially eaten into its concrete foundation, coming within about 30 cm (1 ft) of leaking into the ground". A Kyoto University nuclear engineer said with regard to these estimates: "We just can't be sure until we actually see the inside of the reactors." Unit 2 was the only other operating reactor which experienced a total loss of AC and DC power. Before

4902-496: The primary containment vessel. Therefore, the steam would manually be released by venting valves to prevent a high pressure explosion. The 9.0 M W earthquake occurred at 14:46 on Friday, 11 March 2011, with the epicenter off of the east coast of the Tōhoku region . It produced maximum ground g-force of 560 Gal , 520 Gal, 560 Gal at units 2, 3, and 5 respectively. This exceeded the seismic reactor design tolerances of 450 Gal, 450 Gal, and 460 Gal for continued operation, but

4988-496: The process of restarting seawater injection was interrupted by another explosion in unit 3 RB at 11:01 which damaged water lines and prompted another evacuation. Injection of seawater into unit 1 would not resume until that evening, after 18 hours without cooling. Subsequent analysis in November 2011 suggested that this extended period without cooling resulted in the melting of the fuel in unit 1, most of which would have escaped

5074-468: The reactor by operating the safety relief valves using batteries collected from nearby automobiles. This was shortly followed by the bursting of the venting line rupture disk and the depressurization of the PCV. Unfortunately, venting was quickly stopped by a pneumatic isolation valve which closed on the vent path due to a lack of compressed air, and venting was not resumed until over 6 hours later once an external air compressor could be installed. Despite this,

5160-414: The reactor operators began planning to lower the PCV pressure by venting. The PCV reached its maximum pressure of 0.84 MPa at 02:30 on 12 March, after which it stabilized around 0.8 MPa. The decrease in pressure was due to an uncontrolled vent via an unknown pathway. The plant was notified Okuma town completed evacuation at 9:02 on 12 March. The staff subsequently began controlled venting. Venting of

5246-399: The reactor pressure was immediately low enough to allow for water injection (borated freshwater, as ordered by TEPCO) using the FP system until the freshwater FP tanks were depleted, at which point the injected coolant was switched to seawater from the valve pit. Cooling was lost once the valve pit was depleted but was resumed two hours later (unit 1 cooling was postponed until the valve pit

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5332-426: The reactor vessel. However, the reactor pressure had already increased to many times greater than the limit of the DDFP. Additionally, the team detected high levels of radiation within the secondary confinement structure, indicating damage to the reactor core, and found that the primary containment vessel (PCV) pressure (0.6  MPa ) exceeded design specifications (0.528 MPa). In response to this new information,

5418-603: The release of radioactive contaminants into the surrounding environment. The accident was rated seven (the maximum severity) on the International Nuclear Event Scale by Nuclear and Industrial Safety Agency, following a report by the JNES (Japan Nuclear Energy Safety Organization). It is regarded as the worst nuclear incident since the Chernobyl disaster in 1986, which was also rated a seven on

5504-506: The remaining electricity on site. This would lower the reactor pressure sufficiently to allow for low-pressure injection of water into the reactor using the fire protection system to replenish water lost to evaporation. Station operators switched the reactor control to off-site power for shutdown, but the system was damaged by the earthquake. Emergency diesel generators (EDG) then automatically started to provide AC power. Two EDGs were available for each of units 1–5 and three for unit 6. Of

5590-455: The seismic values were within the design tolerances of unit 6. Upon detecting the earthquake, all three operating reactors (units 1, 2, and 3) automatically shut down. Due to expected grid failure and damage to the switch station as a result of the earthquake, the power station automatically started up the EDGs, isolated the reactor from the primary coolant loops, and activated the emergency shutdown cooling systems. The largest tsunami wave

5676-489: The site for the project and San Antonio had signed on as a partner in the project. Brown and Root was selected as the architect and construction company. On November 17, 1973 voters in Austin narrowly approved their city's participation and the city signed onto the project on December 1. Austin held several more referendums through the years on whether to stay in the project or not. An application for plant construction permits

5762-518: The steam-driven auxiliary feedwater pumps. They were not back in service until March (Unit 1) and May (Unit 2) of 1994. The history of STNP is somewhat unusual since most nuclear plants that were in the early stages of engineering construction at the time of the Three Mile Island event were never completed. On June 19, 2006, NRG Energy filed a letter of intent with the NRC to build two 1,358-MWe advanced boiling water reactors (ABWRs) at

5848-625: The televised news media. Citizens were informed by radio, trucks with megaphones, and door to door visits. Many municipalities independently ordered evacuations ahead of orders from the national government due to loss of communication with authorities; at the time of the 3 km evacuation order, the majority of residents within the zone had already evacuated. Due to the multiple overlapping evacuation orders, many residents had evacuated to areas which would shortly be designated as evacuation areas. This resulted in many residents having to move multiple times until they reached an area outside of

5934-412: The tsunami, operators attempted to manually open the IC control valve, but the IC failed to function, suggesting that the isolation valves were closed. Although they were kept open during IC operation, the loss of DC power in unit 1 (which occurred shortly before the loss of AC power) automatically closed the AC-powered isolation valves to prevent uncontrolled cooling or a potential LOC. Although this status

6020-462: The tsunami. The isolation condenser (IC) was functioning prior to the tsunami, but the DC-operated control valve outside of the primary containment had been in the closed position at the time to prevent thermal stresses on the reactor components. Some indications in the control room stopped functioning and operators correctly assumed loss of coolant (LOC). At 18:18 on 11 March, a few hours after

6106-489: Was 13–14 m (43–46 feet) high and hit approximately 50 minutes after the initial earthquake, overtopping the seawall and exceeding the plant's ground level, which was 10 m (33 ft) above sea level. The waves first damaged the seawater pumps along the shoreline, 10 of the plant's 13 cooling systems for the emergency diesel generators (EDG). The waves then flooded all turbine and reactor buildings, damaging EDGs and other electrical components and connections located on

6192-721: Was a major contractor for the construction of the South Texas plants. In the summer of 1985, Goldstein identified safety problems to SAFETEAM, an internal compliance program established by EBASCO and Houston Lighting, including noncompliance with safety procedures, the failure to issue safety compliance reports, and quality control violations affecting the safety of the plant. SAFETEAM was promoted as an independent safe haven for employees to voice their safety concerns. The two companies did not inform their employees that they did not believe complaints reported to SAFETEAM had any legal protection. After he filed his report to SAFETEAM, Goldstein

6278-457: Was damaged and the isolation valve for the PCV vent was found to be closed and inoperable. At 13:00 on the 14th, the RCIC pump for unit 2 failed after 68 hours of continuous operation. With no way to vent the PCV, in response, a plan was devised to delay containment failure by venting the reactor vessel into the PCV using the SRVs to allow for seawater injection into the reactor vessel. The following morning (March 15, 06:15), another explosion

6364-416: Was established nearly simultaneously at 21:23. The evacuation radius was expanded to 10 km at 5:44, and was then revised to 20 km at 18:25. The size of these evacuation zones was set for arbitrary reasons at the discretion of bureaucrats rather than nuclear experts. Communication between different authorities was scattered and at several times the local governments learned the status of evacuation via

6450-639: Was filled). However, despite being cooled, PCV pressure continued to rise and the RPV water level continued to drop until the fuel became uncovered on the morning of the 14th (6:20), as indicated by a water level gauge, which was followed by workers evacuating the area out of concerns about a possible second hydrogen explosion similar to unit 1. Shortly after work resumed to reestablish coolant lines, an explosion occurred in unit 3 RB at 11:01 on March 14, which further delayed unit 1 cooling and damaged unit 3's coolant lines. Work to reestablish seawater cooling directly from

6536-535: Was fired. Subsequently, Goldstein filed suit under federal nuclear whistleblower statutes. The U.S. Department of Labor ruled that his submissions to SAFETEAM were protected and his dismissal was invalid, a finding upheld by Labor Secretary Lynn Martin . The ruling was appealed and overturned by the Fifth Circuit Court of Appeals , which ruled that private programs offered no protection to whistleblowers. After Goldstein lost his case, Congress amended

6622-533: Was heard on site coinciding with a rapid drop of suppression chamber pressure to atmospheric pressure, interpreted as a malfunction of suppression chamber pressure measurement. Due to concerns about the growing radiological hazard on site, almost all workers evacuated to the Fukushima Daini Nuclear Power Plant . Although AC power was lost, some DC power was still available in unit 3 and the workers were able to remotely confirm that

6708-412: Was lost in units 1, 2, and 4. In response, the operators assumed a loss of coolant in units 1 and 2 and developed a plan in which they would vent the primary containment and inject water into the reactor vessels with firefighting equipment. Tokyo Electric Power Company ( TEPCO ), the utility operator and owner, notified authorities of a "first-level emergency". Two workers were killed by the impact of

6794-424: Was manually reconfigured at 05:00 to recirculate water from the suppression chamber instead. On the 13th, unit 2 was configured to vent the PCV automatically (manually opening all valves, leaving only the rupture disk) and preparations were made to inject seawater from the valve pit via the FP system should the need arise. However, as a result of the explosion in unit 3 the following day, the seawater injection setup

6880-404: Was not possible, as the reactor was not producing sufficient steam. However, the water within the RPV proved sufficient to cool the fuel, with the SRVs venting into the PCV, until AC power was restored on March 13 using the unit 6 interconnection, allowing the use of the low-pressure pumps of the residual heat removal (RHR) system. Unit 5 was the first to achieve a cold shutdown in the afternoon on

6966-400: Was planned but later cancelled. Houston Lighting %26 Power Co. Houston Lighting & Power Co. ( HL&P ), later named Reliant Energy HL&P/Entex , was the single power and utility company that served Greater Houston of the U.S. state of Texas . It was a subsidiary of Houston Industries (HI, NYSE : HOU), which later was renamed to Reliant Energy (REI). HL&P had

7052-854: Was relieved as architect/engineer in September 1981 and Bechtel Corporation contracted to replace them. Less than two months later, Brown and Root withdrew as the construction contractor and Ebasco Constructors was hired to replace them in February 1982 as constructor. Austin voters authorized the city council on November 3, 1981 to sell the city's 16 percent interest in the STP. No buyers were found. Unit 1 reached initial criticality on March 8, 1988 and went into commercial operation on August 25. Unit 2 reached initial criticality on March 12, 1989 and went into commercial operation on June 19. In February 1993, both units had to be taken offline to resolve issues with

7138-757: Was submitted to the Atomic Energy Commission, now the Nuclear Regulatory Commission (NRC), in May 1974 and the NRC issued the permits on December 22, 1975. Construction started on December 22, 1975. By 1978, the South Texas Project was two years behind schedule and had substantial cost overruns. A new management team had been put in place by HL&P in late 1978 to deal with the cost overruns, schedule delays and other challenges. However, events at Three Mile Island in March 1979 had

7224-448: Was sufficient water remaining in the SFP. On the 20th, water was sprayed into the uncovered SFP, later replaced by a concrete pump truck with a boom on the 22nd. Unit 5 was fueled and was undergoing an RPV pressure test at the time of the accident, but the pressure was maintained by an external air compressor and the reactor was not otherwise operating. Removal of decay heat using the RCIC

7310-413: Was the largest of the two stakeholders in the proposed reactors, to purchase an initial 9.2375% stake in the expansion for $ 125 million, and $ 30 million for an option to purchase an additional stake in the new units for $ 125 million more (resulting in approximately 18% ownership by TEPCO, or 500 MW of generation capacity). The agreement was made conditional upon STNP securing construction loan guarantees from

7396-435: Was unknown to the plant operators, they correctly interpreted the loss of function in the IC system and manually closed the control valves. The plant operators would continue to periodically attempt to restart the IC in the following hours and days, but it did not function. The plant operators then attempted to use the building's fire protection (FP) equipment, operated by a diesel-driven fire pump (DDFP), to inject water into

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