京都大学 / 新制・課程博士 / 博士(エネルギー科学) / 甲第23290号 / エネ博第415号 / 新制||エネ||80(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻 / (主査)教授 石原 慶一, 教授 手塚 哲央, 教授 大垣 英明 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

Bibliography: pages 112-138. / The large volume of seawater used for cooling at Koeberg Nuclear Power Station contains many planktonic organisms which are exposed to heat, chlorine and physical stress during their passage through the system. Phytoplankton biomass, measured as chlorophyll a, was reduced by an average of 55.32% due to entrainment, and productivity was decreased by 38.30% on average, mainly due to chlorination. Zooplankton mortality averaged 22.34% for all species and 30.52% for copepods, the dominant group. The copepod Paracartia africana was used in laboratory experiments designed to simulate entrainment. Latent mortality was monitored up to 60 hours after a 30-minute application of stress factors (physical stress was not simulated), and approximately 75% of the total mortality occurred within the 30-minute period. Male Paracartia experienced higher mortalities than females. Extrapolation of these results predicts an overall entrainment mortality (including latent mortality) of 40% for copepods and 29.04% for total zooplankton, although the latter cannot be substantiated. Plankton entrainment at Koeberg was not considered to be overly detrimental to the marine environment because of the very localised area affected, rapid dispersion of heat and chlorine, rapid regeneration times of phytoplankton and some zooplankton, low abundance of commercially important species and potential recruitment from the surrounding productive Benguela upwelling region.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Bibliography: Ref 1-Ref 7. / by Walter Herbert Strohmayer. / Ph.D.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第17796号 / エネ博第279号 / 新制||エネ||58(附属図書館) / 30603 / 京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻 / (主査)教授 下田 宏, 教授 手塚 哲央, 教授 釜江 克宏 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

Sweden is generally considered to be a low seismicity area, but for structures within nuclear power facilities, the safety level demand with respect to seismic events are high and thus, these structures are required to be earthquake-resistant. The seismic hazard is here primarily considered to be associated with near-field earthquakes. The nuclear power plants are further founded on hard rock and the expected ground motions are dominated by high frequencies. The design earthquake considered for the nuclear facilities has an annual probability of 10-5 events, that is, the probability of occurrence is once per 100 000 years. The focus of the study is the seismic response of large concrete structures for the nuclear power industry, with regard not only to the structure itself but also to non-structural components attached to the primary structure, and with emphasis on Swedish conditions. The aim of this licentiate thesis is to summarize and demonstrate some important aspects when the seismic load is dominated by high frequencies. Additionally, an overview of laws, regulations, codes, standards, and guidelines important for seismic analysis and design of nuclear power structures is provided. The thesis includes two case studies investigating the effect of seismic high-frequency content loads. The first study investigates the influence of gaps in the piping supports on the response of a steel piping system subjected to a seismic load dominated by high amplitudes at high frequencies. The gaps are found in the joints of the strut supports or are gaps between the rigid box supports and the pipe. The piping system is assessed to be susceptible to high-frequency loads and is located within the reactor containment building of a nuclear power plant. The stress response of the pipe and the acceleration response of the valves are evaluated. The second study investigates the effect of fluid-structure interaction (FSI) on the response of an elevated rectangular water-containing concrete pool subjected to a seismic load with dominating low and high frequencies, respectively. The pool is located within the reactor containment building of a boiling water reactor at a nuclear power plant. The hydrodynamic pressure distribution is evaluated together with the stress distribution in the walls of the tank. From the two case studies, it is evident that the response due to a seismic load dominated by high frequencies and low frequencies, respectively, is different. Although the seismic high-frequency load may be considered non-damaging for the structure, the effect may not be negligible for non-structural components attached to the primary structure. Including geometrical non-linear effects such as gaps may however reduce the response. It was shown that the stress response for most of the pipe elements in the first case study was reduced due to the gaps. It may also be that the inclusion of fluid-structure interaction effects changes the dynamic properties of a structural system so that it responds significantly in the high frequency range, thus making it more vulnerable to seismic loads dominated by high frequencies. In the second case study, it was shown that even for a seismic load with small amplitudes and short duration, but with dominating high-frequency content, as the Swedish 10-5 design earthquake, the increase of the dynamic response as fluid-structure interaction is accounted for is significant. / <p>QC 20150519</p>

Studien har utförts på uppdrag av en avdelning som arbetar med säkerhet och kvalitet på ett svenskt kärnkraftverk. Avdelningen ansvarar bland annat för analys och värdering av säkerhetskulturen samt kunskapsspridning inom området. Bristande säkerhetskultur har vid flera tillfällen varit orsaken till kärnkraftsolyckor och ledarskap anses vara en viktig faktor för att utveckla och upprätthålla en stark säkerhetskultur. På kärnkraftverket arbetar skiftlag dygnet runt. Skiftlagen har i uppdrag att leda den operativa driften och varje skiftlag har en skiftchef. Denna studie har syftat till att undersöka skiftchefens beteenden och erfarenheter som ledare inom organisationen samt identifiera eventuella utveklingsområden gällande ledarskapet och dess förutsättningar.  Studien är kvalitativ och datainsamlingen består av nio intervjuer som analyserats via tematisk analys. Skiftcheferna som grupp uppvisar flera beteenden som enligt ledarskapsmodellen Stärkande ledarskap bidrar till mer säkra beteenden hos medarbetarna. Arbetsmetoder och de nära relationerna i skiftlaget är en möjlig faktor till att vissa beteenden som en stärkande ledare bör uppvisa främjas. Däremot framgår det att beteenden kopplade till bland annat att förklara företagsbeslut och mål, vilket är en viktig del i att upprätthålla en stark säkerhetskultur, inte uppvisas.  Skiftcheferna uttrycker flera utmaningar i sin roll och det framgår även en skillnad i hur skiftcheferna upplever att vara ledare och vad ett ledarskap innebär. Kärnkraftverket uppmanas att undersöka vidare hur man kollektivt kan arbeta med ledarskapsutveckling och vem som är i behov av att utveckla ledarskapskompetenser. / This study has been carried out on behalf of a unit working with safety and quality at a Swedish nuclear power plant. The unit is responsible for tasks such as analyzing and evaluating safety culture, as well as spreading knowledge within the field. Insufficient safety culture has been identified as a contributing factor to nuclear accidents, and leadership is considered an important factor in developing and maintaining a strong safety culture. The nuclear power plant is operated by shift teams on a round-the-clock basis, with each team being led by a shift manager. This study aims to investigate the behaviors and experiences of shift managers in their role as a leader within the organization and identify areas for development regarding leadership and its prerequisities.  The study is qualitative, and the data collection consists of nine interviews that have been analyzed using thematic analysis. The shift managers as a group show several behaviors that according to the leadership model of Empowering leadership contribute to safer behaviors from the employees. It is possible that the work methods and close relationships within the shift team promote certain behaviors that an empowering leader should demonstrate. However, it appears that behaviors linked to explaining company decisions and goals, which is an important aspect of maintaining a strong safety culture, are not shown.  The shift managers express sedveral challenges in their role and there is also a distinction in their perception of leadership and its implications. The nuclear power plant is encouraged to durther examine how they can collectively work on leadership development and identify indiciduals in need of developing leadership competencies.

The purpose of this study has been to investigate if and how the Swedish Moderate party´s views and ideas regarding nuclear energy, within the energy production has changed in the timeframe of 2010 - 2021. This has been investigated through an idea analysis.The study's research question was asked as follows: Have the Swedish Moderate party´s views and ideas regarding nuclear energy within energy production changed within the timeframe 2010 - 2021? And if that is the case, how have the views and ideas changed?The material that this study used to maintain its purpose contained motions from the Swedish Moderate party within the time frame 2010 - 2021. The motions involved nuclear energy.The conclusion of this study is that the Swedish Moderate party has changed its views and ideas concerning energy politics focusing on nuclear energy. The changes are marginal. However, the Energiöverenskommelsen is an anomaly regarding this case. Energiöverenskommelsen does not match the views and ideas presented by the Swedish Moderate party within the study´s timeframe.

In order to find the optimal placement for a nuclear power plant (NPP) many different factors have to be taken into consideration. Choosing the wrong location could result in higher construction costs and/or taking avoidable risks. GIS can be used to compare different spatial criteria efficiently. There are currently six nuclear reactors operating in Sweden, producing approximately 40% of the total electricity produced in the country every year. These reactors are divided over three nuclear power plants: Ringhals, Forsmark and Oskarshamn. The objective of this thesis is to evaluate the suitability of existing NPPs location in Sweden according to the current standards and guidelines and find good potential sites for a new hypothetical NPP in Sweden. The thesis is limited to investigate the geographical aspects of siting an NPP, and therefore economic decisions and law restrictions will have less impact on the end result. The methodology of the thesis is in line with International Atomic Energy Agency’s step by step siting procedure that includes a site survey in which candidate areas are derived using a set of exclusionary and avoidance criteria. This is followed by the comparison and ranking of these sites by implementing a suitability analysis in the site selection process to derive potential sites. The site survey process result in a map layer containing the candidate areas that fulfills the spectre of exclusionary and avoidance criteria set by the analyst. The site selection process includes weighting criteria compared to each other using the analytic hierarchy process which is based on the perceived importance of each criterion. The criteria are found in an initial study of available literature. Based on the gathered information, data is collected to execute the analysis in ArcMap. Both vector operations and raster calculations are made to produce the end result map layers. The analysis shows that Forsmark is the most suitable location for an NPP among the existing sites. Neither of the existing sites is considered a candidate site, but that depends heavily on how strict the avoidance criteria is set. Three candidate areas were chosen to be further investigated; Sjötorp, Mariefred and Vanneberga. Between these three Sjötorp was determined to be the most suitable location to site an NPP. One conclusion that can be drawn is that more knowledge in the nuclear power industry and more insight in the weighting part would probably lead to more accurate results. It is hard to know how accurate the model is but it could definitely be used and modified for further studies, either with the same goal in mind or with a different goal and modified criteria. / För att hitta det optimala området för ett kärnkraftverk måste man ta hänsyn till flera kriterier. Fel val av område kan resultera i extra konstruktionskostnader och/eller onödiga säkerhetsrisker. GIS kan användas för att jämföra geografiska kriterier på ett effektivt sätt. Idag finns det sex stycken reaktorer i bruk i Sverige. Dessa producerar ungefär 40% av landets el. Reaktorerna är fördelade på tre stycken anläggningar: Ringhals, Forsmark och Oskarshamn. Syftet med detta arbete är att utvärdera lämpligheten av placeringen av de existerande kärnkraftverken i Sverige i enlighet med nutida standarder och riktlinjer och att hitta bra potentiella områden för ett nytt hypotetiskt kärnkraftverk i Sverige. Arbetet är begränsat till att undersöka de geografiska aspekterna av nyförläggningsprocessen och därmed har ekonomiska beslut och lagrestriktioner mindre påverkan på slutresultatet. Metodiken för arbetet är i linje med IAEAs steg för steg nyförläggningsprocedur som inkluderar en site survey där candidate areas tas fram genom att använda en rad med kriterier för områden som antingen ska exkluderas eller undvikas. Dessa områden jämförs och rankas sedan genom att implementera en suitability analysis i site selection processen för att framhäva potentiella områden. Site survey processen resulterar i ett kartlager med de kandidatområdena som uppfyller spektrumet av kriterier som analytikern har bestämt antingen ska exkluderas eller undvikas. Site selection processen inkluderar att vikta kriterier i förhållande till varandra med hjälp av den så kallade analytic hierarchy process som baseras på den uppfattade vikten av varje kriterium. Kriterierna formuleras efter en initial litteraturstudie. Baserat på den samlade informationen hämtas data för att kunna utföra analysen i ArcMap. Både vektoroperationer och rasterberäkningar utförs för att producera de kartlager som sedan återfinns i slutresultatet. Analysen visar att Forsmark är den bäst lämpade platsen för ett kärnkraftverk utav de områdena där existerande kärnkraft är placerade. Inget av de existerande områdena anses vara ett kandidatområde, men det beror till stor del på hur strikt de kriterier som ska undvikas är satta. Tre kandidatområden valdes för vidare undersökning; Sjötorp, Mariefred och Vanneberga. Av dessa tre ansågs Sjötorp vara det bäst lämpade området för ett kärnkraftverk. En slutsats som kan dras är att djupare kunskap inom kärnkraftsindustrin och mer insikt i viktningen skulle leda till mer exakt resultat. Det är svårt att veta hur exakt modellen är men den skulle definitivt kunna modifieras och användas för framtida studier, antingen med samma slutmål eller med ett annat mål och modifierade kriterier.

An operator's performance and mental workload when interacting with a complex system, such as the main control room (MCR) of a nuclear power plant (NPP), are major concerns when seeking to accomplish safe and successful operations. The impact of performance on operator workload is one of the most widely researched areas in human factors science with over five hundred workload articles published since the 1960s (Brannick, Salas, & Prince, 1997; Meshkati & Hancock, 2011). Researchers have used specific workload measures across domains to assess the effects of taskload. However, research has not sufficiently assessed the psychometric properties, such as reliability, validity, and sensitivity, which delineates and limits the roles of these measures in workload assessment (Nygren, 1991). As a result, there is no sufficiently effective measure for indicating changes in workload for distinct tasks across multiple domains (Abich, 2013). Abich (2013) was the most recent to systematically test the subjective and objective workload measures for determining the universality and sensitivity of each alone or in combination. This systematic approach assessed taskload changes within three tasks in the context of a military intelligence, surveillance, and reconnaissance (ISR) missions. The purpose for the present experiment was to determine if certain workload measures are sufficiently effective across domains by taking the findings from one domain (military) and testing whether those results hold true in a different domain, that of nuclear. Results showed that only two measures (NASA-TLX frustration and fNIR) were sufficiently effective at indicating workload changes between the three task types in the nuclear domain, but many measures were statistically significant. The results of this research effort combined with the results from Abich (2013) highlight an alarming problem. The ability of subjective and physiological measures to indicate changes in workload varies across tasks (Abich, 2013) and across domain. A single measure is not able to measure the complex construct of workload across different tasks within the same domain or across domains. This research effort highlights the importance of proper methodology. As researchers, we have to identify the appropriate workload measure for all tasks regardless of the domain by investigating the effectiveness of each measure. The findings of the present study suggest that responsible science include evaluating workload measures before use, not relying on prior research or theory. In other words, results indicate that it is only acceptable to use a measure based on prior findings if research has tested that measure on the exact task and manipulations within that specific domain.

Nuclear Power Plants (NPP) undergo fault and sensitivity analysis with scenario modelling to predict catastrophic events, specifically releases of Cesium 137 (Cs-137). The purpose of this thesis is to find which of 108 input-features from Modular Accident Analysis Program (MAAP)simulation code are important, when there is large release of Cs-137 emissions. The features are tested all together and in their groupings. To find important features, the Machine learning (ML) model Random Forest (RF) has a built-in attribute which identifies important features. The results of RF model classification are corroborated with Support Vector Machines (SVM), K-Nearest Neighbor (KNN) and use k-folds cross validation to improve and validate the results, resulting in a near 90% accuracy for the three ML models. RF is successful at identifying important features related to Cs-137 emissions, by using the classification model to first identify top features, to further train the models at identifying important input-features. The discovered input-features are important both within their individual groups, but also when including all features simultaneously. The large number of features included did not disrupt RF much, but the skewed dataset with few classified extreme events caused the accuracy to be lower at near 90%.