Risk and Responsibility Sharing in Nuclear Spent Fuel Management

With the Nuclear Waste Policy Act of 1982, the responsibility of American utilities in the long-term management of spent nuclear fuel was limited to the payment of a fee. This narrow involvement did not result in faster or safer development of a solution for commercial nuclear waste. In most other countries, the financial liability and practical involvement of utilities appear more extensive. This paper highlights how such differences in institutional frameworks affect risk sharing and economic incentives. It argues that a greater allocation of risk and responsibility to the utilities should reenter the debate over nuclear waste in the US.Massachusetts Institute of Technology, Center for Energy and Environmental Policy Research. EPRI and the Idaho National Laboratory

Nuclear Fuel Recycling - the Value of the Separated Transuranics and the Levelized Cost of Electricity

We analyze the levelized cost of electricity (LCOE) for three different fuel cycles: a Once-Through Cycle, in which the spent fuel is sent for disposal after one use in a reactor, a Twice-Through Cycle, in which the spent fuel is recycled for a second use in a light water reactor after which the spent fuel is sent for disposal, and a Fast Reactor Recycle in which all of the transuranics are repeatedly recycled in fast reactors. We carefully define the LCOE and provide a simple solution method that involves simultaneously calculating the value of the recycled materials, whether plutonium or the transuranics. We parameterize our formulas and calculate the LCOEs. Earlier reports do not provide general formulas and solution methods for calculating the LCOE. We contrast our methodology with the definitions and solution methods employed in various prior reports, and we compare our parameter inputs and resulting LCOEs. For example, we show that the ‘equilibrium cost’ of fast reactor systems as calculated in other studies exaggerates the LCOE. Our calculations show that, based on current estimates of the costs for the various activities, recycling increases the LCOE by between 1.7 and 2.8 mills/kWh. This is an approximately 20-34% increase in the fuel cycle cost of the Once-Through Cycle, which we estimate at 8.28 mill/kWh. This is an approximately 2-4% increase in the total LCOE of the Once-Through Cycle, which we estimate at 75.32 mill/kWh. For the Twice- Through Cycle, the separated plutonium has a negative value, meaning that a reactor will have to be paid to take the recycled plutonium. For the Fast Reactor Cycle, the separated transuranics have a negative value, meaning that a fast reactor will have to be paid to take the transuranics.Massachusetts Institute of Technology. Center for Energy and Environmental Policy Research

Economics of nuclear fuel cycles : option valuation and neutronics simulation of mixed oxide fuels

Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student submitted PDF version of thesis.Includes bibliographical references (p. 71-73).In most studies aiming at the economic assessment of nuclear fuel cycles, a primary concern is to keep scenarios economically comparable. For Uranium Oxide (UOX) and Mixed Oxide (MOX) fuels, a traditional way to achieve this is to evaluate both fuels on the deterministic premise that the fuel will be sent to geologic disposal once spent. This methodology often leads to higher costs for cycles using MOX fuel. Geologic disposal is not the sole possible ending for spent LightWater Reactor (LWR) fuel. Fast Reactors (FRs), which feed on transuranics (TRUs) extracted from LWR spent fuel, are seriously considered as a future technology. If it is cheaper to extract TRUs from spent MOX than from UOX, then the relative cost of a fuel cycle using MOX fuel may be less than in the case of their geologic disposal. However, the commercial development of FR cycles is uncertain. The value of UOX and MOX is therefore not the deterministic value in case of geologic disposal or in case of reprocessing into FRs. This thesis develops a method to assess the cost of thermal reactor fuel cycles in the presence of uncertainties in back-end management. The representation of future progress in FR technology through a resulting value of TRUs exhibits the properties of MOX as a financial option on the marginal TRU extraction cost. The framework establishes a significant modification of the back-end costs for countries using MOX, compared to traditional valuations. However, these savings do not completely offset the higher costs of recycling in the reference case.by Guillaume De Roo.S.M.S.M.in Technology and Polic

Multivariate analysis identifies the estradiol level at ovulation triggering as an independent predictor of the first trimester pregnancy-associated plasma protein-A level in IVF/ICSI pregnancies

STUDY QUESTION: Can independent predictors of pregnancy-associated plasma protein-A (PAPP-A) levels be identified in a group of women who conceived following IVF/ICSI? SUMMARY ANSWER: The significantly decreased PAPP-A level in IVF and ICSI pregnancies compared with non-IVF/ICSI pregnancies was correlated strongly with the serum estradiol (E2) level at ovulation triggering. WHAT IS KNOWN ALREADY: The first trimester prenatal combined screening test for fetal aneuploidies in pregnancies conceived following assisted reproduction techniques (ART) is complicated by an alteration of the maternal biomarkers free β-hCG and PAPP-A, causing a higher false-positive rate compared with pregnancies which are conceived naturally. The use of controlled ovarian stimulation prior to IVF/ICSI is suggested to be the principle reason for these alterations of biomarkers in ART pregnancies. STUDY DESIGN, SIZE, DURATION: Between January 2010 and December 2011, 1474 women who conceived naturally and 374 women who conceived following IVF (n = 89), ICSI (n = 204) or intrauterine insemination (IUI, n = 81) were included in this retrospective study. Only singleton pregnancies were eligible for this study. For all women, serum analysis was performed in the same clinical laboratory. Measurement of nuchal translucency (NT) thickness was performed by four physicians belonging to the same infertility centre. PARTICIPANTS/MATERIALS, SETTING, METHODS: First-trimester combined screening test of aneuploidy parameters (maternal age, PAPP-A and free β-hCG, NT thickness) were compared between non-ART and ART (IVF, ICSI and IUI) singleton pregnancies. Next, a minimal threshold E2 level at ovulation triggering was suggested for IVF/ICSI pregnancies above which the PAPP-A levels were significantly decreased compared with non-ART pregnancies. Finally, a multivariate analysis was performed to reveal independent predictors of PAPP-A level in IVF/ICSI pregnancies. MAIN RESULTS AND THE ROLE OF CHANCE: We showed a decrease of the multiple of the median (MoM) PAPP-A level in IVF and ICSI singleton pregnancies compared with non-ART singleton pregnancies (P < 0.001), with MoM values of 0.74 (0.16-3.16) and 0.81 (0.12-4.61) versus 0.98 (0.14-5.76), respectively. Analysis of variance of the overall model was highly significant (Fisher test 3.76, P = 0.01), indicating that the model explains a significant portion of the variation in the data. No difference in PAPP-A level was found between non-ART and IUI pregnancies. The free β-hCG level and NT thickness did not differ between ART and non-ART pregnancies. PAPP-A levels in IVF and ICSI pregnancies were strongly correlated with the E2 level at ovulation triggering. We showed by multivariate analysis that an E2 cut-off level of 1300 pg/ml at the time of ovulation could predict a significantly lower PAPP-A level at first trimester combined screening (β -0.239 ± 0.088, P < 0.005). LIMITATION, REASONS FOR CAUTION: The measures of biochemical markers can differ between laboratories and with the used equipment; therefore, extrapolation of the E2 cut-off level to other infertility centres should be undertaken with caution. WIDER IMPLICATIONS OF THE FINDINGS: One should be careful when using correction factors for ART patients undergoing the first trimester combined screening test. The proposed E2 cut-off level may help to identify a subgroup of women within the population of ART patients for whom use of a correction factor is justified. STUDY FUNDING/COMPETING INTEREST(S): None

Microchannel cooling for the LHCb VELO Upgrade I

The LHCb VELO Upgrade I, currently being installed for the 2022 start of LHC Run 3, uses silicon microchannel coolers with internally circulating bi-phase \cotwo for thermal control of hybrid pixel modules operating in vacuum. This is the largest scale application of this technology to date. Production of the microchannel coolers was completed in July 2019 and the assembly into cooling structures was completed in September 2021. This paper describes the R\&D path supporting the microchannel production and assembly and the motivation for the design choices. The microchannel coolers have excellent thermal peformance, low and uniform mass, no thermal expansion mismatch with the ASICs and are radiation hard. The fluidic and thermal performance is presented.Comment: 31 pages, 27 figure

A methodology for calculating the levelized cost of electricity in nuclear power systems with fuel recycling

In this paper we show how the traditional definition of the levelized cost of electricity (LCOE) can be extended to alternative nuclear fuel cycles in which elements of the fuel are recycled. In particular, we define the LCOE for a cycle with full actinide recycling in fast reactors in which elements of the fuel are reused an indefinite number of times. To our knowledge, ours is the first LCOE formula for this cycle. Others have approached the task of evaluating this cycle using an 'equilibrium cost' concept that is different from a levelized cost. We also show how the LCOE implies a unique price for the recycled elements. This price reflects the ultimate cost of waste disposal postponed through the recycling, as well as other costs in the cycle. We demonstrate the methodology by estimating the LCOE for three classic nuclear fuel cycles: (i) the traditional Once-Through Cycle, (ii) a Twice-Through Cycle, and (iii) a Fast Reactor Recycle. Given our chosen input parameters, we show that the 'equilibrium cost' is typically larger than the levelized cost, and we explain why.Levelized cost of electricity Nuclear power Recycling

Le modèle Leviathan sans commérage ou vanité : la richesse d'une influence basée sur la hiérarchie perçue

International audienceThis paper studies a model of agents having an opinion about each other agent and about themselves. During dyadic meetings, the agents change their opinion about themselves and about their interlocutor in the direction of a noisy perception of the opinions of their interlocutor. Moreover highly valued agents are more influential. This model produces several patterns depending on the parameter values. In particular, in some cases several highly influential agents (called leaders) emerge and sometimes the leaders have a low opinion of each other