A new concept of fusion neutron monitoring for PF-1000 device

Abstract

The power output of plasma experiments and fusion reactors is a crucial parameter. It is determined by neutron yields that are proportional and directly related to the fusion yield. The number of emitted neutrons should be known for safety reasons and for neutron budget management. The PF-1000 is the large plasma facility based on the plasma focus phenomenon. PF-1000 is operating in the Institute of Plasma Physics and Laser Microfusion in Warsaw. Neutron yield changes during subsequent pulses, which is immanent part of this type device and so it must be monitored in terms of neutron emission. The reference diagnostic intended for this purpose is the silver activation counter (SAC) used for many years. Our previous studies demonstrated the applicability of radio-yttrium for neutron yield measurements during the deuterium campaign on the PF-1000 facility. The obtained results were compared with data from silver activation counter and shown linear dependence but with some protuberances in local scale. Correlation between results for both neutron monitors was maintained. But the yttrium monitor registered the fast energy neutron that reached measurement apparatus directly from the plasma pinch. Based on the preliminary experiences, the yttrium monitor was designed to automatically register neutron-induced yttrium activity. The MCNP geometrical model of PF-1000 and yttrium monitor were both used for calculation of the activation coefficient for yttrium. The yttrium monitor has been established as the permanent diagnostic for monitoring fusion reactions in the PF-1000 device.

Accelerator based epithermal neutron source for clinical boron neutron capture therapy

“…7, respectively. The dominant dose component was the boron dose (resulting from the alpha particle and 7 Li ion), with the effect being more distinct for the tumour dose (>90%). Normally, for BNCT the dose is prescribed to the healthy tissue (e.g., skin, brain, or mucosal membrane).…”

“…115 In (natural abundance of 95.7%) is excited by the (n, n ) process producing 115m In, which returns to the ground state by emitting a 340 keV gamma ray. The threshold neutron energy of this nuclear reaction is approximately 340 keV [7].Indium also reacts to thermal neutrons that produce both beta and gamma rays with different energies, making the measurement of the 340 keV difficult. To minimise these reactions, the indium foil was covered with cadmium to shield the low energy neutrons.…”

“…where D T represents the total absorbed dose from each component, D B is dose resulting from the 10 B (n, α) 7 Li reaction, D H is the dose from the epithermal and fast neutrons causing reoil protons from hydrogen in tissue, D N is the dose from the 14 N in tissue capturing a thermal neutron and emitting a proton in a 14 N(n, p) 14 C reaction, and D γ is dose from the gamma rays accompanying the neutron beam as well as gamma rays induced in the tissue itself. RBE H , RBE N and RBE γ are relative biological effectiveness (RBE) values of hydrogen, nitrogen, and gamma rays, respectively.…”

An integrated digital framework for the design, build and operation of fusion power plants

“…A digital framework must incorporate large quantities of both design and power plant data; for this to be effective, a new generation of sensors/technologies will need to be developed which are capable of automatic model updates from real-time operational measurements. These developments will need to include both technologies specific to fusion reactors, such as monitoring of power output via neutron yields [53] and of surface morphology of plasma-facing components [54], e.g. breeder blankets, but also more conventional structural health monitoring during operations and non-destructive evaluation during manufacture and maintenance, for instance ultrasound examination of welds [55] and hydrostatic heat sinks [56,57].…”

Absolute determination of the neutron source yield using melamine as a neutron detector

“…In recent years one could notice a growing interest in absolute determining the neutron emission from different accelerator-based sources [22,23] as well as from plasma focus [24,25], inertial confinement fusion [26] and magnetic confinement fusion devices [27]- [33]. The neutron yield is one of the most important parameter to characterize all types of nuclear fusion experiments.…”