Nuclear Power Plant In Taiwan Research Articles

Dose assessment on the impact of accidents with Fukushima nuclear meltdown emission levels at the four nuclear power plants in Taiwan

There is a heated debate for including nuclear power as an important source of energies for pursuing net-zero carbon emission in the coming years. An advanced Gaussian trajectory dispersion model is used to evaluate the consequent impacts of nuclear power plant (NPP) accidents with Fukushima nuclear meltdown emission levels occurring at all of the four power plants (NPP1–NPP4) in Taiwan. Our study indicates the exposure pathway emergency planning zone (EPZ) would be as far as 17, 25, 5 and 17 km downwind from NPP1 to NPP4, respectively, for an event occurring on 11 March 2011. Our study indicates that the percentages of the land in Taiwan becoming permanent evacuation zones (PEZs) are as high as 8%, 13%, 2%, and 11% for an event occurring randomly during a year from 11 March 2011 at NPP1 to NPP4, respectively. The mean percentages of the land for Taipei City becoming PEZs are 35%, 71%, 0% and 48%, respectively. The mean percentages of the land for Kaohsiung City becoming PEZ are 4%, 5%, 5% and 3%, respectively. The analysis shows that for pursuing net-zero carbon emission, the conventional nuclear energy might not be a good choice for Taiwan, since about 2–13% of the Island can be inhabited for more than 30 years while a Fukushima-level nuclear meltdown occurs. The methodology and the trajectory model used here can be applied for other countries for quantifying the EPZ and PEZ for each nuclear power plant to substitute a conventional straight-line-type plume model, such as MACCS2.

International case survey and literature review of maintenance strategy for decommissioning nuclear power plant during transition period

The Chinshan nuclear power plant in Taiwan has currently shutdown when the operating license expired in 2018. However, because the operation license of the independent spent nuclear fuel dry storage facility has not been approved yet, and the fuel storage racks of Spent Fuel Pool (SFP) has almost saturated, there is not enough space to accommodate all irradiated fuels from the reactor core during the transition period. Therefore, part of the mechanical systems, plant structures and electrical equipment of the plant still have to meet the functional requirements for maintaining the safety under the pre-decommissioning activities.In this article, we introduce the international cases of permanent shutdown but the fuel still in the reactor core, and also describe the actions of the Taiwan Power Company in response to this situation. For the providing regulatory advice, we have also proposed a framework of the maintenance strategy associated with important issues for the transition period since 2018, including a revised Aging Management Program (AMP) for keeping the safety of spent nuclear fuel. From the knowledge level and important issues related to the topic, the Phenomena Identification and Ranking Table (PIRT) is quoted to complete the understanding level of requirements during the transition period.

Study Protocol for Radiation Exposure and Cancer Risk Assessment: The Taiwan Nuclear Power Plants and Epidemiology Cohort Study (TNPECS).

This cohort was established to evaluate whether 38-year radiation exposure (since the start of nuclear reactor operations) is related to cancer risk in residents near three nuclear power plants (NPPs). This cohort study enrolled all residents who lived within 8 km of any of the three NPPs in Taiwan from 1978 to 2016 (n = 214,502; person-years = 4,660,189). The control population (n = 257,475; person-years = 6,282,390) from three towns comprised all residents having lived more than 15 km from all three NPPs. Radiation exposure will be assessed via computer programs GASPAR-II and LADTAP-II by following methodologies provided in the United States Nuclear Regulatory Commission regulatory guides. We calculated the cumulative individual tissue organ equivalent dose and cumulative effective dose for each resident. This study presents the number of new cancer cases and prevalence in the residence-nearest NPP group and control group in the 38-year research observation period. TNPECS provides a valuable platform for research and opens unique possibilities for testing whether radiation exposure since the start of operations of nuclear reactors will affect health across the life course. The release of radioactive nuclear species caused by the operation of NPPs caused residents to have an effective dose between 10-7 and 10-3 mSv/year. The mean cumulative medical radiation exposure dose between the residence-nearest NPP group and the control group was not different (7.69; standard deviation, 18.39 mSv and 7.61; standard deviation, 19.17 mSv; P = 0.114).

Deep learning schemes for event identification and signal reconstruction in nuclear power plants with sensor faults

An initiating event (IE) is an event that may lead to core damage in a nuclear power plant (NPP), and being able to identify an IE is crucial in determining what actions to take. This process requires examining the data from the widespread NPP sensors. Any fault in these sensors can be a severe issue that may defer the mitigation action that would bring the NPP back into safe shutdown conditions. In this study, we focus on addressing two issues in this regard: (1) event identification with sensor faults, and (2) faulty sensor signal reconstruction under an IE with the help of two deep learning (DL)-based schemes. Through the superior capability of DL in feature extraction, discriminant information can be extracted to enable valid event identification even when the faulty sensors have been discarded. Owing to the nonlinear nature of the DL network model, the process information for sensor reading generation and the interrelations among the sensors in the event recordings can be used to reconstruct faulty sensor readings without the need for deterministic trend removal. Results from detailed experiments using data generated by a simulator of the Maanshan NPP in Taiwan are provided to illustrate the efficacy of the proposed approaches.

Risk perceptions of nuclear energy, climate change, and earthquake: How are they correlated and differentiated by ideologies?

Nuclear energy is a complicated issue for both the public and policymakers because it is perceived as a possible solution to climate change risk, but it is also a safety concern, especially since the 2011 Fukushima disaster. This paper examines the factors that influence the risk perceptions of nuclear power plants in Taiwan, focusing on the correlations between risk perceptions of nuclear power plants, climate change, and earthquakes. We analyzed the 2013 and 2019 Taiwan Social Change Survey (TSGS) data using the ordinary least squares (OLS) regressions models. The results demonstrate strong positive correlations between the risk perceptions of the nuclear plant, climate change, and the presence of earthquakes.We argue that the public does not consider a “risk–risk trade-off” between climate change and nuclear energy. Instead, the perceptions of all the risk factors are strongly correlated. Women and respondents with conservative political ideology reported higher risk perceptions of nuclear power plants. Since the ruling party switched between the survey date (2013 and 2019), the trust in government significantly correlated with the nuclear risk perceptions very differently. Thus this paper can provide valuable implications contributing to climate and energy policymaking in the future.

Nuclear Power in Taiwan: A Clash of Views

The article addresses the issue of nuclear energy in Taiwan, which became particularly relevant after the 2016 elections, when the winning Democratic Progressive Party (DPP), led by President Tsai Ing-wen, announced the rejection of the use of nuclear energy by 2025. By 2020, adopted against the backdrop of thousands of protests after the Fukushima-1 accident, this course gained many supporters and opponents and became the subject of a political struggle between the currently ruling DPP and its rival Kuomintang. The paper analyzes the reasoning by the parties, describes the opposing organizational structures and their relations with political forces. Three main general issues are in the focus of debates: security, ecology and economics. In security matters, opponents of nuclear energy in Taiwan use the Chernobyl accident and Fukushima-1 as an example, talking about the danger of nuclear energy per se, the inability to control it and ensure an appropriate level of safety of nuclear facilities. Supporters argue that the safety systems of nuclear power plants in Taiwan are superior to those at Fukushima-1, and the company itself is constantly upgrading them. In the ecology sector, the most acute issue is low-level nuclear waste disposal, and the opponents pay much attention to reducing CO2 emissions into the atmosphere. In the area of economic matters, there is a lack of reserve capacity in Taiwan, and the parties emphasize the relatively high cost of alternative environmentally friendly energy sources. Anti-nuclear activists talk about the high costs of building and operating nuclear power plants, arguing that in the long run, nuclear power plants lose out to renewable energy sources both economically and technologically, considering atomic power as an outdated industry.

Assessment of resident doses near nuclear power plants in Taiwan for epidemiology study

Dose assessments were required for the epidemiological study of residents living near nuclear power plants. In the present work, environmental pathway models have been applied to estimate radiation doses to residents living near the nuclear power plants in Taiwan. Best estimates of doses were made for residents by their age groups in different compass sectors centered at the nuclear power plants. In each sector, radiation doses were assessed using the averaged environmental, consumption and lifestyle data. For epidemiological analyses of cancer risks in different organs or tissues, individual organ absorbed doses were assessed for both the airborne and waterborne effluent releases. Such assessments were performed based on the historic data, including measured effluent releases, detected meteorological parameters, and surveyed data on the production and consumption of local agricultural, fishery and livestock products, etc. Exposure pathways consisted of the external irradiations from air submersion, ground deposition and water immersion plus the internal irradiations from inhalation and ingestion. Age-dependent annual intakes and occupancy time were locally surveyed. Dose conversion coefficients were taken from published data after International Commission on Radiological Protection Publication 60. Annual doses and cumulated doses during residence were assessed and examined for their dependence on age, organ and compass sector.

Demonstration of Structural Integrity of Boiling Water Reactor Pressure Vessels Under Ultimate Response Guideline Operation

In recent years, the compound beyond-design-basis accident (BDBA), which combines earthquake, tsunami, or some other severe events to impact a nuclear power plant (NPP), has received more attention. After the Fukushima nuclear disaster, the licensee of NPPs in Taiwan established the ultimate response guideline (URG) that instructs operators to perform reactor depressurization, low-pressure water injection, and containment venting to prevent core meltdown and hydrogen explosion once long-term loss-of-power and water-supply events occur. In this paper, we employed the probabilistic fracture mechanics (PFM) method to evaluate the structural integrity of boiling water reactor (BWR) pressure vessels under URG operation. At first, models of the beltline shell welds for BWR vessels associated with the Pressure Vessel Research Users Facility-Exponential flaw distribution were built for the PFM Fracture Analysis of Vessels–Oak Ridge (FAVOR) code. Then, the thermal-hydraulic data of URG transients for Taiwan domestic BWRs were imposed as the loading conditions. The analysis results demonstrate that performing URG operation will not cause significant fracture probability even at extreme embrittlement conditions. If long-term station blackout occurs due to a compound BDBA, the URG procedures can prevent core damage and hydrogen explosion, while maintaining the structural integrity of the reactor pressure vessels.

Thermal Spray Coatings of Al, ZnAl and Inconel 625 Alloys on SS304L for Anti-Saline Corrosion

Stainless steel 304L (SS304L) has been selected as the material for canisters for spent fuel storage from three nuclear power plants in Taiwan. A crucial issue is extending the spent fuel storage safety standards of the canisters. The anti-saline corrosion abilities of three thermal spray coatings (i.e., Al, ZnAl, and 625 Inconel alloys) on the SS304L were evaluated by immersion in 3.5 wt % aqueous NaCl and with 0.025 g/cm2 NaCl deposition at 80 °C and 80% relative humidity (RH) for 1000 h. The pristine thermal spray coatings were examined using the pull-off adhesion test to understand the adhesion strength, and Vickers hardness was measured for the mechanical properties of the three coatings. Confocal laser scanning microscopy (CLSM) was used to identify the porosities of the coatings. Furthermore, the surfaces of the specimens before and after corrosion were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS). The composition and distribution of the oxide layers formed on the coating surfaces during corrosion were evaluated. Electrochemical measurement was also performed with the polarization method to quantify the corrosion property of the three thermal spray coatings. The results showed that the corrosion rate of Al coating was lowest from the Tafel analysis after the 1000 h corrosion test in 3.5% aqueous NaCl. In contrast, the corrosion rate of Inconel 625 was lowest after 1000 h of the NaCl deposition corrosion test in a controlled environment. Therefore, the ZnAl thermal spray coating is a potential protection layer, keeping in mind economic considerations, of SS304L for anti-corrosion in saline environments.

Sensor fault detection, isolation and reconstruction in nuclear power plants

The widespread sensors in a nuclear power plant (NPP) provide vital support to its operation. Any fault in these sensors can be a severe issue, threatening the safety of the NPP. Thus, the detection and isolation of the problematic sensors and the reconstruction of their readings are essential. In this study, several algorithms for sensor fault detection, isolation, and signal reconstruction are proposed. Through simultaneously monitoring changes in the recordings from sensors of the same type, an anomaly can be detected while the preset thresholds are exceeded. No subjective reasoning is required in setting the thresholds. To prevent improper recovery actions, an interquartile range-based scheme is employed to avoid falsely linking the variations in sensor readings caused by an initiating event (IE) to those caused by sensor faults. Moreover, via a sequential backward selection-based approach, the faulty sensors can be effectively isolated without the need for checking all the installed ones when the variations are deemed to be caused by sensor faults. Lastly, multivariate autoregressive model-based approaches are introduced to reconstruct the readings of faulty sensors either when an NPP is in normal operation or during the occurrence of an IE. Results of experiments using data generated by a simulator of the Maanshan NPP in Taiwan are provided to illustrate the efficacy of the proposed approaches.

Largescale mullet (Planiliza macrolepis) can recover from thermal pollution-induced malformations.

It is well known in aquaculture that hyperthermic perturbations may cause skeleton malformations in fish, but this phenomenon has rarely been documented in wild species. One rare location where thermal pollution has increased the proportion of malformed fish in wild population is in the waters near the Kuosheng Nuclear Power Plant in Taiwan. At this site, the threshold temperature and critical exposure time for inducing deformations have not been previously determined. In addition, it was unclear whether juvenile fish with thermal-induced malformations are able to recover when the temperature returns below the threshold. In the present study, juvenile largescale mullet (Planiliza macrolepis) were kept at temperatures ranging from 26°C and 36°C for 1–4 weeks, after which malformed fish were maintained at a preferred temperature of 26°C for another 8 weeks. The vertebrae bending index (VBI) of fish was increased after 2 weeks at 36°C, and deformed vertebral columns were detected by radiography after 4 weeks. However, malformations were not observed in groups kept at or below 34°C. Moreover, at the end of the recovery period, both the VBI and the vertebrae malformations had returned to normal. The results of this study may help to more precisely determine potential environmental impacts of thermal pollution and raise the possibility that the capacity for fish vertebrae to recover from the impacts of chronic thermal exposures may be an important consideration in marine fish conservation.

Probabilistic Risk Assessment of Station Blackouts in Nuclear Power Plants

Adequate ac power is required for decay heat removal in nuclear power plants. Station blackout (SBO) accidents, therefore, are a very critical phenomenon to their safety. Though designed to cope with these incidents, nuclear power plants can only do so for a limited time, without risking core damage and possible catastrophe. Their impact on a plant's safety are determined by their frequency and duration, which quantities, currently, are computed via a static fault tree analysis that deteriorates in applicability with increasing system size and complexity. This paper proposes a novel alternative framework based on a hybrid of Monte Carlo methods, multistate modeling, and network theory. The intuitive framework, which is applicable to a variety of SBOs problems, can provide a complete insight into their risks. Most importantly, its underlying modeling principles are generic, and, therefore, applicable to non-nuclear system reliability problems, as well. When applied to the Maanshan nuclear power plant in Taiwan, the results validate the framework as a rational decision-support tool in the mitigation and prevention of SBOs.

Crack Growth and Tolerance of Stainless Steel Canisters in the Marine Environment

Most of the dry storage cask systems that are used to contain nuclear fuel are austenitic stainless steel canisters. Past experience suggests that stainless steel is susceptible to stress corrosion cracking (SCC) in the presence of chloride salts. A crack growth rate (CGR) model has been developed and applied to evaluate the crack depth in stainless steel canisters over the timeframe of the storage at independent spent fuel storage installations. This study focuses on stainless steel canisters for dry storage systems in the two nuclear power plants in Taiwan. The crack depth was first evaluated using the CGR model, site climate data, and canister surface temperature. The critical crack size and depth were then determined from the structural tolerance assessment of the canister shells. It was found that the variations in the thermal and hydraulic properties of dry storage canisters produce large variations in the SCC initiation time but do not affect the surface temperature in the range of 55–60 °C. The CGR at the SCC initiation is high and the growth of flaws is significant. The surface temperature and CGR decrease with time. The total crack depth therefore may not vary greatly as a function of SCC initiation time. Overall, dry storage canisters show high structural tolerance to crack size and depth.

Incorporating Tidal Uncertainty into the Methodology of Probabilistic Tsunami Hazard Analysis

Wu, E.C.; Chen, Y.L.; Wu, H.L.; Hu, K.C.; Hsiao, S.C., and Wu, Y.C., 2018. Incorporating Tidal Uncertainty into the Methodology of Probabilistic Tsunami Hazard Analysis. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 691–695. Coconut Creek (Florida), ISSN 0749-0208.The Circum-Pacific Belt has become active in recent years, and the earthquake in the border area of land and sea probably causes tsunami disaster. The hazard includes overflow flooded, building damage, casualties, and radiation crisis of nuclear power plant. To quantify the risk, probabilistic tsunami hazard analysis (PTHA) serves as a robust methodology. The uncertainty stemming from the deviation of modeling, named aleatory uncertainty, is considered with including the tidal effect on the tsunami. To deal with the aleatory uncertainty, we incorporate tidal uncertainty into PTHA. Different static tidal stages are set in Cornell Multi-grid Coupled Tsunami model (COMCOT) to evaluate tsunami hazards. Three kinds of method are presented. One could apply theoretical probability distribution to different maximum wave height by the Gaussian Method. On the other hand, the Δt method and the Pattern Method combine tsunami events with a typical year of tidal record. The difference between these methods are discussed, and the Pattern Method is regarded as the most rigorous way. Finally, the method of incorporating tidal uncertainty into PTHA has been established and been utilized to Maanshan nuclear power plant in Taiwan.

Safety analysis methodology for Chinshan nuclear power plant spent fuel pool under Fukushima-like accident condition

Abstract Chinshan nuclear power plant (NPP), a BWR/4 plant, is the first NPP in Taiwan. After Fukushima NPP disaster occurred, there is more concern for the safety of NPPs in Taiwan. Therefore, in order to estimate the safety of Chinshan NPP spent fuel pool (SFP), by using TRACE, MELCOR, CFD, and FRAPTRAN codes, INER (Institute of Nuclear Energy Research, Atomic Energy Council, R.O.C.) performed the safety analysis of Chinshan NPP SFP. There were two main steps in this research. The first step was the establishment of Chinshan NPP SFP models. And the transient analysis under the SFP cooling system failure condition (Fukushima-like accident) was performed. In addition, the sensitive study of the time point for water spray was also performed. The next step was the fuel rod performance analysis by using FRAPTRAN and TRACE's results. Finally, the animation model of Chinshan NPP SFP was presented by using the animation function of SNAP with MELCOR analysis results.

Probabilistic Tsunami Hazard Analysis — Application to Maanshan Nuclear Power Plant in Taiwan

ABSTRACT Wu, E.C.; Ma, W.H., Chen, Y.L.; Wu, H.L.; Hu, K.C.; Hsiao, S.C. and Wu, Y.C., 2016. Probabilistic Tsunami Hazard Analysis — Application to Maanshan Nuclear Power Plant in Taiwan. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 1267 - 1271. Coconut Creek (Florida), ISSN 0749-0208. In the past twelve years, two earthquakes of magnitude 9.0 have occurred in the western Pacific. These earthquakes resulted in tsunamis, causing tremendous casualties, such as the nuclear disaster in Japan on March, 2011. Taiwan is an island located in the circum-Pacific belt, along which approximately 90% of the world's largest earthquakes take place. To prevent hazards, probabilistic tsunami hazard analysis (PTHA) is applied to nuclear power plants in the coastal regions of Taiwan. The approach developed here allows for the selection of reasonable tsunamis gene...

Characterization of crud deposited on fuel rods under HWC environment in Kuosheng Nuclear Power Plant

Under normal water chemistry conditions, the oxygen and hydrogen peroxide produced by water radiolysis in the coolant of boiling water reactors (BWRs) can lead to intergranular stress corrosion cracking in the constituent materials of plant components. This fact has led to the wide-scale adoption of hydrogen water chemistry (HWC) in the nuclear industry to counteract these effects. This study seeks to characterize the metallic composition and the surface properties of the constituent materials of plant components in order to determine their effects on the accumulation of chalk river unidentified deposits (crud) on fuel rods in the BWR Unit-1 of the Kuosheng Nuclear Power Plant in Taiwan. Inductively coupled plasma-atomic emission spectroscopy was used to calculate the concentrations of surface crud and gamma spectrometry was used to determine the radioactivity of the corrosion products, as well as their axial distribution across the surface of the fuel rods. X-ray diffraction analysis and scanning electron microscopy/energy-dispersive X-ray spectroscopy were used to identify the crystalline phase and morphology of the crud as irregular shapes and flakes. The amount of crud deposited during the fourth fuel cycle exceeded that of the third fuel cycle due to extended burn-up time. Our analytical results indicate that the implementation of HWC had no significant effect on the characteristics of subsequent crud.

Cancer incidence in the vicinity of nuclear power plants in Taiwan: a population-based study.

Numerous antinuclear demonstrations reveal that the public is anxious about the potential health effects caused by nuclear power plants. The purpose of this study is to address the question "Is there a higher cancer incidence rate in the vicinity of nuclear power plants in Taiwan?" The Taiwan Cancer Registry database from 1979 to 2003 was used to compare the standardized incidence rate of the top four cancers with strong evidence for radiation risks between the "plant-vicinity" with those "non-plant-vicinity" groups. All cancer sites, five-leading cancers in Taiwan, and gender-specific cancers were also studied. We also adopted different observation time to compare the incidence rate of cancers between two groups to explore the impact of the observation period. The incidences of leukemia, thyroid, lung, and breast cancer were not significantly different between two groups, but cervix uteri cancer showed higher incidence rates in the plant-vicinity group. The incidence of cervical cancer was not consistently associated with the duration of plant operation, according to a multiyear period comparison. Although there was higher incidence in cervix cancer in the plant-vicinity group, our findings did not provide the crucial evidence that nuclear power plants were the causal factor for some cancers with strong evidence for radiation risks.

Enhancing post-nuclear temporary housing solutions in Taiwan

The nuclear accidents in Chernobyl in Ukraine in 1986 and Fukushima in Japan in 2011 shocked the world. Because of the widespread release of radiological materials during these accidents, tens of thousands of citizens were evacuated from their houses. Since post-nuclear decontamination is time-consuming, resettling evacuees in temporary housing facilities became imperative. If a nuclear accident occurs in one of the four nuclear power plants in Taiwan, Taiwanese government agencies would have difficulty accommodating evacuees because of unavailable resettlement sites, inappropriate housing layouts, and delayed construction projects. Therefore, to assist Taiwanese government agencies to prepare post-nuclear temporary housing solutions, this study proposes an approach that integrates computer simulation-, Building Information Modeling (BIM)-, and project management-based information techniques. In a simulated scenario, this study examined the efficiency of this approach. The tests revealed that Taiwanese government agencies effectively selected resettlement sites, confirmed housing layouts, and scheduled construction projects. Overall, the results of this study can be of help in similar applications of emergency management regarding nuclear accidents.

Negative pressure difference evaluation of Lungmen ABWR containment by using GOTHIC

Negative pressure difference of the pressure suppression containments means that the wetwell pressure is greater than the drywell pressure and is an undesired effect to the containment safety. The Wetwell-to-Drywell Vacuum Breakers (WDVBs) are check valves used to mitigate this adverse effect. The Lungmen Nuclear Power Plant in Taiwan is a twin-unit Advanced Boiling Water Reactor (ABWR) plant. There are totally 8 WDVBs in the ABWR containment. In this study, a GOTHIC model is developed to evaluate the negative pressure difference of the Lungmen plant. Sensitivity study on the operable WDVB number is also performed. The results show that there is sufficient margin against the negative pressure difference for the ABWR containment. The design value will not be exceeded unless only one WDVB is operable. Furthermore, the effect of the WDVB leakage on the drywell pressure is evaluated by performing the short-term containment analyses. The peak drywell pressure will be greater than the design value with leakage area greater than 50% of one WDVB area. Based on the results of this study, the current requirement that all WDVBs shall be closed and operable during normal operation ensures the Lungmen containment safety.