Neutron activation of PF-1000 device parts during long-term fusion research

Abstract

The neutron flux emitted from fusion devices induces many different nuclear reactions that can activate the vacuum chamber and irradiate operators. A c-spectrometer was mounted inside the Plasma Focus (PF) PF-1000, the world's largest plasma focus facility, after completing a campaign. Qualitative analysis was performed following a lengthy c-spectrum acquisition period. Instrumental neutron activation analysis identified the elemental composition of the vacuum chamber for use by a Monte Carlo N-Particle simulation. In this way, the radioactivity accumulated inside the PF-1000 as the function of time was calculated.

Radiation hazards in PF-1000 plasma generator fusion research

“…The plasma-focus devices are actually widely explored in the field of fusion research however recently also were used in other applications [5]. This is a continuation of a recently published paper that described activation of vacuum vessel materials by D-D plasmas [6], and prompt EMIR accompanying plasma generation inside the PF-1000 [7].…”

Radiation hazards in PF-1000 plasma generator fusion research (part 2)

“…The active part of the dosimeter probe is a cylindrical proportional counter (40 9 100 mm) filled with a mixture of 3 He and methane. This design, which mainly measures thermal neutrons, has a registration efficiency of approximately 90 %.…”

“…Basing on the dependence of H*(10) n on a particular discharge and the annual neutron yield [2,3], the annual ambient dose equivalent was estimated for the particular positions over the period from 2001 to 2013. The final values of effective doses correspond to the situation where personnel are situated in the specific positions during all realized discharges [4,6].…”

“…We have already reported on the radiation safety challenges posed by the release of electromagnetic ionizing radiation, and by neutron activation of surrounding materials in the facility [2][3][4][5][6]. In this study we aimed to characterize the radiation hazard posed to personnel by neutron streams by the PF-1000.…”

Radiative thermal neutron-capture cross sections for theW180(n,γ)reaction and determination of the neutron-separation energy

“…b Calculated partial γ-ray production cross sections assuming the isotopic abundances of the 11.35%-enriched 180 tungsten where 181 W represents a major contaminant activity [14][15][16][17]. Furthermore, 180 W has been identified as a candidate progenitor for an artificial neutrino source (with 181 W the β − -decaying radioactive product) which could be used in the calibration of neutrino detectors [18,19] as well as for studying fundamental properties of the neutrino itself.…”