R.J. Cerbone

Bio: R.J. Cerbone is an academic researcher. The author has contributed to research in topics: Fusion power & Nuclear transmutation. The author has an hindex of 3, co-authored 7 publications receiving 30 citations.

Spherical tokamak (ST) transmutation of nuclear wastes

Abstract: The concept for an ST fusion core that drives a He-cooled, actinide-bearing, molten-salt blanket of moderate power density to generate electricity is examined for the first time. The results show that the fusion core is suited for this purpose and require a level of plasma, power density, engineering, and material performances moderate in comparison with what has been considered desirable for fusion-only power plants. The low aspect ratio of ST introduces a relatively thick, diverted scrape-off layer which leads to reduced heat fluxes at the limiter and divertor tiles. The use of a demountable, water-cooled, single-turn copper center leg for the toroidal field coils enables simplifications of the fusion core configuration and improves overall practicality for future power applications. These result in much reduced size and cost of the fusion core for the transmutation power plant relative to an optimized fusion-only fusion core. Surrounded by a separate tritium-breeding zone, the molten-salt blanket concept is in principle less complex and costly than the thermal breeding blankets for fusion. These combine to effect major reductions in the cost and weight of the power core equipment for the transmutation power plant. The minimum cost of electricity for such a power plant is thus reduced from the best fusion-only counterpart by more than 30%, based on consistent but approximate modeling. The key issues, development steps, and the potential value inherent in the ST fusion core in addressing the world needs for nuclear waste reduction and energy production are discussed.

Disposition of plutonium in a fusion driven subcritical assembly

Abstract: Fusion is one of the options to destroy weapons and spent-fuel plutonium. A fusion reactor with high temperature helium cooled graphite blanket was investigated as a potential plutonium transmutation reactor. Neutronics performance and plutonium isotopic composition during the burn-up were calculated. In addition to the destruction of a large quantity of plutonium, the cost of electricity for the plutonium transmutation plant can be significantly lower than for a pure fusion power plant.

Science and Technology of the 10-MA Spherical Tori

Abstract: The scientific parameters and the technology issues for a modest size spherical torus (ST) at 10 MA plasma current are discussed. This class of devices includes a DT-capable ST experiment (DTST, R0 = 1.2 m) for extended plasma performance tests for limited pulse lengths and neutron fluences, and a volume neutron source (VNS, R0 = 1.1 m) for steady state energy technology testing to high neutron fluences. The scientific issues of interest for DTST include non-inductive ramp-up of plasma current on a limited timescale (~30 s), the confinement needed for high Q burn, the behaviour of energetic particles, the physics and techniques to handle intense plasma exhaust, and the possibility of high performance plasma regimes free of disruptions or large disruption impact. Of further interest for the VNS would be steady state operation using large external current drive, possibly at a modest Q (~1-2), achieving significant neutron wall loading (~1 MW/m2) and a configuration relatively amenable to remote maintenance. A much longer timescale would be permitted in a VNS for non-inductive current ramp-up. The centre leg of the toroidal field coils, possibly multiturn for DTST and necessarily single turn for a VNS without significant nuclear shielding, presents technical and material issues of unique importance to the ST. Positive ion neutral beam injection and high harmonic fast wave (~80 MHz) heating and current drive systems already available are likely to be adequate for DTST following pulse length extension to ~50 s. Given an adequate physics database, the remaining enabling technologies needed for the VNS appear largely similar in nature to those of the ITER EDA design.

Progress of the ST-VNS Study

Abstract: Progress is given on the investigation of a low cost, scientifically attractive, and technologically feasible volumetric neutron source (VNS) based on the spherical torus (ST) concept. The ST-VNS h...

Recent progress on spherical torus research

Abstract: The spherical torus or spherical tokamak (ST) is a member of the tokamak family with its aspect ratio (A = R0/a) reduced to A ∼ 1.5, well below the normal tokamak operating range of A ≥ 2.5. As the aspect ratio is reduced, the ideal tokamak beta β (radio of plasma to magnetic pressure) stability limit increases rapidly, approximately as β ∼ 1/A. The plasma current it can sustain for a given edge safety factor q-95 also increases rapidly. Because of the above, as well as the natural elongation κ, which makes its plasma shape appear spherical, the ST configuration can yield exceptionally high tokamak performance in a compact geometry. Due to its compactness and high performance, the ST configuration has various near term applications, including a compact fusion neutron source with low tritium consumption, in addition to its longer term goal of an attractive fusion energy power source. Since the start of the two mega-ampere class ST facilities in 2000, the National Spherical Torus Experiment in the United St...

Next-step spherical torus experiment and spherical torus strategy in the course of development of fusion energy

Abstract: A spherical torus (ST) fusion energy development path which is complementary to the proposed tokamak burning plasma experiments such as ITER is described. The ST strategy focuses on a compact component test facility (CTF) and high performance advanced regimes leading to more attractive Demo and power plant scale reactors. To provide the physical basis for the CTF an intermediate step needs to be taken, which we refer to as the 'next-step spherical torus' (NSST) device and which we examine in some detail herein. NSST is a 'performance extension' stage ST with a plasma current of 5?10?MA, R = 1.5?m, BT ? 2.6?T and the possibility of varying physical parameters. The mission of NSST is to (1) provide a sufficient physical basis for the design of a CTF; (2) explore advanced operating scenarios with high bootstrap current fraction and high performance which can be utilized by CTF, Demo, and power plants; and (3) contribute to the general science of high ? toroidal plasmas. The NSST is designed to utilize a TFTR-like site to minimize the cost and time required for design and construction.

Spherical Torus Pathway to Fusion Power

Abstract: Spherical Torus (ST) as an example of confinement concept innovation to enable a potentially attractive pathway to fusion power is discussed. Given the anticipated high performance in small size, the ST plasma could be used to stimulate innovation also in engineering, technology, and material combinations to provide a smarter, cheaper, faster pathway. This pathway could complement the mainline program based on the tokamak in making the desired progress in fusion energy sciences. The ST pathway could include a small VNS (Volume Neutron Source) with low fusion amplification (Q ∼ 1–2) for Fusion Energy Development (energy technology) and a small Pilot Plant with high Q (∼15–30) to practice Fusion Power Demonstration. Success in these steps also enhances the possibility for competitive non-electric applications of interest to society in time scales shorter than electric power generation. The scientific basis for these possibilities will be tested in the U.S. by the Proof of Principle experiment NSTX (National Spherical Torus Experiment) presently being built, and could be completed by a Proof of Performance and Optimization experiment such as a small DTST (Deuterium-Tritium Spherical Torus). Utilization of facilities and equipment already available in the U.S. would minimize the time and cost for these experiments and accelerate the approach to the stage of Fusion Energy Development.

The Fusion Hybrid as a Key to Sustainable Development

Abstract: If world development is to continue, mid-century energy requirements are daunting. For world development, per capita energy use in the developing world must be brought up to levels in the already developed world. Restrictions on how much CO2 mankind can responsibly put into the atmosphere may complicate the task further. Studies show that by 2050 the world will require an additional 10–30 terawatts (TW) of carbon free power, at least as much additional, as the 10 TW generated today with fossil fuel. This paper suggests that the fusion hybrid is one of rather few possibilities for generating this power economically, in an environmentally acceptable way, and with little proliferation danger.