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1

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

Jednorog S., Laszynska E., Bienkowska B., Ziolkowski A., Paduch M., Szewczak K., Mikszuta K., Malinowski K., Bajdel M., Potrykus P.

Nukleonika

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2017

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Vol. 62, No. 1

17--22

EN

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.

2

Determination of the emission rate for the 14 MeV neutron generator with the use of radio-yttrium

Laszynska E., Jednorog S., Ziolkowski A., Gierlik M., Rzadkiewicz R.

Nukleonika

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2015

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Vol. 60, No. 2

319--322

EN

The neutron emission rate is a crucial parameter for most of the radiation sources that emit neutrons. In the case of large fusion devices the determination of this parameter is necessary for a proper assessment of the power release and the prediction for the neutron budget. The 14 MeV neutron generator will be used for calibration of neutron diagnostics at JET and ITER facilities. The stability of the neutron generator working parameters like emission and angular homogeneity affects the accuracy of calibration other neutron diagnostics. The aim of our experiment was to confi rm the usefulness of yttrium activation method for monitoring of the neutron generator SODERN Model: GENIE 16. The reaction rate induced by neutrons inside the yttrium sample was indirectly measured by activation of the yttrium sample, and then by means of the γ-spectrometry method. The pre-calibrated HPGe detector was used to determine the yttrium radioactivity. The emissivity of neutron generator calculated on the basis of the measured radioactivity was compared with the value resulting from its electrical settings, and both of these values were found to be consistent. This allowed for a positive verifi cation of the reaction cross section that was used to determine the reaction rate (6.45 × 10–21 reactions per second) and the neutron emission rate (1.04 × 108 n·s–1). Our study confi rms usefulness of the yttrium activation method for monitoring of the neutron generator.

3

Occupational exposure to Am-Be neutron calibration source mounted in OB26 shielding container

Szewczak K., Jednorog S.

Nukleonika

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2014

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Vol. 59, No. 3

97--103

EN

Laboratory for Dosimetric and Radon Instruments Calibration which is a part of Central Laboratory for Radiological Protection (CLRP) in Warsaw is equipped with 241Am-Be neutron calibration source with activity of 185 GBq since 1999. The capsule was mounted in the OB26 type shielding container. The control room is separated from the above source by a concrete wall of 0.5 m in thickness. The calibration hall is adjacent to one side of the offi ce room. To comply with the requirements of the radiological protection system, the occupational exposure of persons that are working both in the offi ce and control room needs to be assessed. Two methods were involved for ambient dose equivalent rate determination. The active instrument measurements (AIMs) performed with the Berthold LB6411 neutron probe and the Monte Carlo simulation method (MCS) based on MCNP5 code. These estimations were completed for fi ve reference points. Additionally the γ-radiation component was measured by RSS131 ionisation chamber. An increased value of the ambient dose equivalent rate from neutrons was observed in two reference positions. The fi rst observation was done in the control room while the second one in the offi ce room. Expected individual dose equivalents were evaluated based on the results of the AIM and on the expected working time in particular reference points. The annual individual dose equivalent associated with calibration activities using mentioned neutron source was estimated at maximum 0.8 mSv.

4

PF-6 an effective plasma focus as a source of ionizing radiation and plasma streams for application in material technology, biology and medicine

Gribkov V., Dubrovsky A., Scholz M., Jednorog S., Karpiński L., Tomaszewski K., Paduch M., Miklaszewski R., Pimenov V., Ivanov L. I., Dyomina E. V., Maslyaev S. A., Orlova M. A.

Nukleonika

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2006

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Vol. 51, nr 1

55-62

EN

A review of results on the design and operation of the new efficient Dense Plasma Focus device PF-6 of medium size (transportable) having bank energy of ca. 7 kJ and possessing a long lifetime is presented. New data on the interaction of the pulsed fast ion beams and dense plasma streams generated at this apparatus with various materials are given. These results are compared with the analogous information received at the biggest facility PF-1000. It is shown that it is possible to have about the same power flux density (in the range of 105 109 W/cm2) in both devices however in different areas. Doses of soft X-rays produced by the device within the resists for the goals of microlithography and micromachining appear to be several times less that it is with the conventional X-ray tube. In biological application of this device, medium- and hard-energy X-rays are exploited in the field of radioenzymology. It was found that the necessary dose producing activation/inactivation of enzymes can be by several orders of magnitude lower if used at a high-power flux density in comparison with those received with isotope sources. In medicine, short-life isotope production for the goals of the positron emission tomography (medicine diagnostics) is possible by means of the fast ions generated within DPF. All these experiments are discussed in the framework of pulsed radiation physics and chemistry in its perfect sense thereto the criteria are formulated.