This paper assesses the uncertainty associated with the utilization and implementation of advanced fuel cycles to control plutonium inventories. The specific fuel cycles investigated are a partially closed cycle utilizing MOX reactors and completely closed one-tier fuel cycles utilizing fast reactors. Multiple methods for assessing these uncertainties were utilized. A scenario approach that varied the time and number of the implementation of the advanced reactors was used. It was found that the implementation of 3 FR/yr with a CR of 0.5 could reduce the amount of Pu by over 36% in reference to building 3 LWR/yr. In addition to reducing the inventory with respect to the reference LWR case, the growth rate can be reduced from an initial 22 tons Pu/ year growth to 5 tons Pu / year growth with the 2030 actual initial Pu inventory implementation cases. The MOX cases keep the Pu/ TWhe inventory slightly above 1 ton Pu/TWhe and the extremely low CR FR cases even lower than that value. Thus from this work the extremely low CR FR scenarios show the greatest ability to control the growing Pu inventory. In addition to the scenario approach a Monte Carlo uncertainty model was developed and analyzed. The uncertainty analysis showed the high burn up cases are comparable with the of the low CR FR cases in there ability to control the Pu inventory with the Pu inventories ranging from 2500 tons of Pu to 7500 tons of Pu. However, for the high burn up cases the majority of the Pu is Out-Of-Pile as opposed to the FR cases where a considerable amount of the Pu is In-Pile. From a proliferation stand point, the low CR FR case is better at the controlling the Pu inventory because the total inventories are relatively the same for the majority of the runs, and the FR cases keep most of the Pu In-Pile rather than the high burn up cases which keep most of it Out-Of-Pile. Lastly, a brief economic uncertainty model was developed. The economic results show that the once-through cycle is the cheapest with over 50% of the test cases coming in cheaper than all of the FR and MOX cases. The FR cases come out to be the next cheapest with the MOX cases being the most expensive.

Cavitation is a significant concern for the reliable operation of a centrifugal pump. Liquid metal flow loops are used in nuclear, chemical, metal forming, and liquid metal dynamo applications. Understanding of the cavitation characteristics of liquid metals is increasingly important to the design and operation of these facilities. One recent field of cavitation research has developed for mercury flow in spallation targets used in neutron sources. To further the understanding of mercury cavitation, a review of the existing literature on water cavitation, liquid metal cavitation, and mercury cavitation is performed. The mechanics of cavitation and the analytical methods applied to cavitation problems are discussed and analyzed. Acoustic data from the centrifugal pump for the mercury flow loop at the Spallation Neutron Source in Oak Ridge National Laboratory are examined.

The hydrocyclone is commonly used to separate oil from water, and particulates from fluid streams in various process industries. Two-fluid hydrodynamic theory is used here to develop a model for hydrocyclone performance in the application of separation of helium bubbles larger than 30 micron in diameter from liquid mercury at system pressure near 1 bar. The application is related to high power liquid metal target development for proton beams used in spallation neutron sources.

The use of Bonner Sphere Spectrometer (BSS) is a well-established method of measuring the energy distribution of neutron emission sources. The purpose of this research is to apply the Generalized Regression Neural Network (GRNN), a kind of Artificial Neural Network (ANN), to predict the neutron spectrum using the count rate data from a BSS. The BSS system was simulated with the MCNP5 Monte-Carlo code to calculate the response to neutrons of different energies for each combination of thermal neutron detector and polyethylene sphere. One hundred and sixty-three different types of neutron spectra were then investigated. GRNN Training and testing was carried out in the MATLAB environment. In the GRNN testing, eight-one predicted spectra were obtained as outputs of the GRNN. Comparison with standard spectra shows that 97.5% of the prediction errors were controlled below 1%, indicating ANN could be used as an alternative with high accuracy in neutron spectrum unfolding methodologies. Advantages and further improvements of this technique are also discussed.

ANSI/ANS 8.3 “Criticality Accident Alarm System”, Appendix B states “Determining the adequacy of criticality alarm detector placement is far from an exact process”. With this statement in mind a novel method for establishing areas of acceptable Criticality Accident Alarm System (CAAS) coverage was developed and demonstrated utilizing Los Alamos’ Monte Carlo N-Particle Code 5 (MCNP5) in multigroup Adjoint. Validation of the methodology was shown in the comparison of benchmark calculations with empirical results of Sandia testing and with hand calculations utilizing ANS 8.3. Demonstration involved the determination of zones of CAAS coverage from detector sensitivity maps generated by MCNP5 for a conceptual geometry of a new storage facility involving homogenized concrete and BoroBond® slabs. Multiple detector coverage was further demonstrated through the superimposing of several maps corresponding to differing detector locations.

<p>Precisely-known fission yield distributions are used to determine a fissioning isotope and the incident neutron energies in nuclear security applications. 14 MeV neutrons from DT fusion at the National Ignition Facility (NIF) induced fission in depleted uranium (DU) contained in the target assembly hohlraum. The fission yields of Kr isotopes (85m, 87, 88, 89, and 90) were measured relative to the cumulative yield of 88Kr. The fission gas was pumped from the target chamber, collected, and analyzed in the Radiochemical Analysis of Gaseous Samples (RAGS) diagnostic. Isotopes with half-lives ranging 8 s-9 hr can be measured. Kr fission yields have been measured both from the fission of DU in the hohlraum and DU doped into the capsule ablator. Since the mass of U was not known, the relative amounts of Kr isotopes were calculated and compared to existing fission product distribution tables. It was found that measurements can be performed with high precision for isotopes with half lives longer than 4 minutes. A more precise quantification of gas transport needs to be achieved to quantify isotopes with shorter half lives to a precision of the published tables.

Up to this time, the design of Pressurizers in Nuclear Power Plants has been quite empirical due to the deficiency of standard thermodynamic relationships when applied to the solution of two phase systems. Recently, a new thermodynamic approach was expounded to the 2nd Nuclear Engineering and Science Conference which attempts to deal with the problem of two phase systems by breaking the thermodynamic unit into various subsystems and solving each separately. However, no experimental proof of the new theory was given. The object of this investigation was to prove or disprove the validity of this new thermodynamic approach as applied to the prediction of the performance of a Pressurizer. A small, simplified model of a pressurizer was constructed, and surge tests were conducted. The surges were then calculated by means of the new thermodynamic equations and compared with the actual results. It was found that the prediction of pressurizer surges depends greatly upon the exactness to which the transient heat loss to the walls of the pressurizer can be calculated. Nevertheless, the use of standard heat transfer relationships when used in the theoretical surge equations, predicted the pressure surges to within 40%. An attempt to obtain closer theoretical results by determining the transient heat loss from pressure and temperature decay curves was unsuccessful due to improper pressure recording equipment. Some doubt has been cast on one of the assumptions of the theoretical equations, in that the pressurizer steam was not compressed isentropically as assumed. It is felt that this deviation from the theoretical was due to the small size of the model pressurizer, but proof of this is left to future experimenters. This investigation did prove that with this new thermodynamic approach of subsystems, and with the use of standard heat transfer expressions, the performance of nuclear power plant pressurizers can be predicted within reasonable limits. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1991. / Title as it appears in the June, 1991 M.I.T. Graduate List: Geochemistry and petrogenesis of basalts from Broken Ridge and Naturaliste Plateau, S.E. Indian Ocean. / Includes bibliographical references (leaves 47-48). / by Mahmood A. Cheema. / Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1991.

The future role of nuclear power in global sustainable development, and particularly in the development of industrialising countries is contentious; the debate is often highly emotive. The Republic of South Africa's (RSA) progress towards its largest nuclear procurement program is taking place in the midst of changes within the African National Congress (ANC) ruling party, an increase in global demand for uranium and growing energy needs within South Africa. Major nuclear accidents such as Chernobyl or Fukushima have set nuclear power plant security on top of the public agenda. The internalisation of governance through the creation of responsible eco-citizenship is a primary technique to screen perceived risk, which works through the course of public participation. Participation however, must include those that drive the objectives within the nuclear context. Eskom's Koeberg Nuclear Power Station (KNPS) has a workforce of more than 2000 employees. In 2016, the Department of Energy (DOE) had decided that Africa's leading power utility will be the owner operator and procurer of the planned 9.6 Gigawatts (GW) (e) nuclear fleet that is set out in the IRP2010 report. The perceptual impact of this workforce that keeps the country's economic lifeblood moving is often understated, which was the focus of this study. This study had a distinct focus on what Eskom employee's perceptions are with respect to the IRP2010 nuclear new build program. It was limited to the Western Cape Province and included views from divisions that may be involved in the realisation of the nuclear project. It is unique in its context, as very little has been documented on employee perception within RSA's nuclear industry. It is comparative to a public perception survey, which had a distinct focus on nuclear risk. The public's greatest concerns were noted to be corruption, project mismanagement, excessive cost and lack of trust in stakeholders. The outcome of this study discovered similarities with the public perception survey, however here within nuclear safety and compliance to business best practice were greater significant factors. Most respondents had sufficient knowledge and support for RSA's nuclear plans set out in the IRP reports. Dimensions of how perception was created were voted as being heavily dependent on the leadership within the organisation. With this in mind, Eskom employees have indicated that they are more likely to influence the public if they have their leadership's support, and have gone as far as selecting nuclear power over renewable energy to drive towards the country's commitment towards low greenhouse gas (GHG) emissions. So while there may be shades of perceptual similarities between the public and Eskom employees, fundamentally this study revealed that these two bodies do not have the same perception on nuclear power. The study revealed that if Eskom employee's nuclear perception is disregarded and mismanaged, it may delay the realisation of the nuclear new build program in line with IRP 2010 timelines. This is mainly due to the concern of adherence to good corporate governance by Eskom's leadership.

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