Technical preparations for the in-vessel 14 MeV neutron calibration at JET

Batistoni, P.; Popovichev, S.; Crowe, R.D.; Čufar, Aljaž; Ghani, Z.; Keogh, K.; Peacock, Alan T.; Price, R.; Baranov, A.; Korotkov, S. A.; Lykin, P.; Samoshin, A. V.

doi:10.1016/j.fusengdes.2017.01.023

Cited by 10 publications

(5 citation statements)

References 5 publications

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“…Another useful check is to compare the calculated and measured neutron rates. The total neutron rate from fusion reactions, including the thermal, beam-thermal, and beambeam fusion, is measured by the fission chambers at JET [6]. TRANSP calculates the synthetic neutron rate data with the given input profiles and Z eff with the NUBEAM module [22] using the following formula: For the DD discharges, pure deuterium fuel gas is assumed and the thermal ion density is n thermal,D = n e − ∑ j n imp,j Z imp,j and n thermal,T = 0 in equation (3).…”

Section: Data Consistencymentioning

confidence: 99%

“…Hence, in preparation for the optimized ITER operation, it is necessary to demonstrate the transferability of the operation scenarios to the DT mixture plasmas in the ILW, and investigate the impact on the fusion performance. In addition, the 2020 JET-DTE2 will provide a good opportunity for study of isotope effects [5] and alpha particle physics, and the improvement of DT operation technology [6] such as tritium cycling, 14 MeV neutronics, remote handling, etc.…”

Section: Introductionmentioning

confidence: 99%

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1997 JET DT experiments revisited—comparative analysis of DD and DT stationary baseline discharges

et al. 2020

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This paper compares the stationary ELMy H-mode baseline 50%-50% deuterium-tritium (DT) mixture discharges in the first high -power JET DT experimental campaign in 1997 (JET-DTE1) with the counterpart 100% deuterium (DD) baseline discharges which have the same engineering parameters, i.e. I p , B t , q 95 , NBI power, plasma shape, no gas dosing, divertor structure, and the carbon wall. There is no difference in profile peaking of T e , T i , and n e between the DT and the counterpart DD baseline discharges, indicating that there was no isotopic effect on the core transport in the stationary baseline DT discharges in the 1997 JET-DTE1. The core values of T e , T i , and n e are higher in some DT discharges compared to their counterpart DD discharges, but this is attributed to the higher pedestal values, rather than any improvement in the core transport. The interpretive TRANSP simulations also show that the local heat diffusivity is not consistently different between the DT and the counterpart DD baseline discharges.The baseline discharges in the 1997 JET-DTE1 are also compared to the latest high-power ELMy H-mode baseline DD discharges with an ITER-like wall (ILW) in 2016. Despite the similar effective collisionality and ion heat deposition in the core, it was observed that T i /T e is consistently close to unity in the 1997 JET-DTE1 discharges, while the 2016 JET baseline discharges have high T i , exceeding T e , which enabled the highest fusion performance in the ITER-Like Wall. The high rotation frequency was the key factor in increasing T i /T e in the 2016 JET baseline discharges, and it is also the main difference compared to the stationary baseline discharges in the 1997 JET-DTE1. Based on this, it is prospected that higher rotation frequency is the key factor to achieving high fusion power in the stationary baseline discharges in the 2020 JET-DTE2, and the plasma operation with the low gas dosing and increased torque available in the present NBI system would enable such a high rotation frequency.

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Section: Data Consistencymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

1997 JET DT experiments revisited—comparative analysis of DD and DT stationary baseline discharges

et al. 2020

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“…It can measure the distribution of particle number and size. − According to the equivalent projection particle size, the light flux, which is blocked by particles, is received through the shading sensor and converted into electrical signals, which are transmitted to the counter through the preamplifier for counting. However, the trace free water suspended in jet fuel can also shield the light, which interferes with the results of the automatic particle counting method. − …”

Section: Introductionmentioning

confidence: 99%

Research on the Influence of Cosolvent on the Determination of the Contamination Degree of Jet Fuel

Mao¹,

Zheng²,

et al. 2020

ACS Omega

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The effect of cosolvent on trace free water in the determination of the contamination degree of jet fuel was investigated. The interference of trace free water on the automatic particle counter can be eliminated by adding isopropanol as a cosolvent to the measured oil sample. Isopropanol can dissolve trace free water in oil. Addition of isopropanol could stabilize the pollution grade of particles with size ≥30 μm (c) at the same level, which is most obviously affected by free water without isopropanol. The standard uncertainty u(X 1 ) is slightly reduced with the addition of isopropanol, and the repeatability and accuracy of the automatic particle counting method are obviously improved. The results show that isopropanol should be added as a cosolvent to eliminate the interference of free water when the contamination degree of jet fuel oil samples with obvious free water is determined by the automatic particle counting method.

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“…The constraints and early decisions which defined the main calibration approach, e.g. the RH compatibility and the limited space available, the technical requirements of the 14 MeV NG and the deployment method and the safety and engineering aspects have been discussed in a separate paper [5]. As the NG is not a stable neutron source, several monitoring detectors are attached to it by means of an ad hoc mechanical structure to continuously monitor the neutron emission rate and the total neutrons emitted during the in-vessel calibration.…”

Section: Introductionmentioning

confidence: 99%

14 MeV calibration of JET neutron detectors—phase 2: in-vessel calibration

et al. 2018

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A new DT campaign (DTE2) is planned at JET in 2020 to minimize the risks of ITER operations. In view of DT operations, a calibration of the JET neutron monitors at 14 MeV neutron energy has been performed using a well calibrated 14 MeV neutron generator (NG) deployed, together with its power supply and control unit, inside the vacuum vessel by the JET remote handling system. The NG was equipped with two calibrated diamond detectors, which continuously monitored its neutron emission rate during the calibration, and activation foils which provided the time integrated yield. Cables embedded in the remote handling boom were used to power the neutron generator, the active detectors and pre-amplifier, and to transport the detectors’ signal. The monitoring activation foils were retrieved at the end of each day for decay γ-ray counting, and replaced by fresh ones. About 76 hours of irradiation, in 9 days, were needed with the neutron generator in 73 different poloidal and toroidal positions in order to calibrate the two neutron yield measuring systems available at JET, the 235U fission chambers (KN1) and the inner activation system (KN2). The NG neutron emission rates provided by the monitoring detectors were in agreement within 3%. Neutronics calculations have been performed using MCNP code and a detailed model of JET to derive the response of the JET neutron detectors to DT plasma neutrons starting from the response to the NG neutrons, and taking into account the anisotropy of the neutron generator and all the calibration circumstances. These calculations have made use of a very detailed and validated geometrical description of the neutron generator and of the modified MNCP neutron source subroutine producing neutron energy-angle distribution for the neutrons emitted by the NG. The KN1 calibration factor for a DT plasma has been determined with ±4.2% experimental uncertainty. Corrections due to NG and remote handling effects and the plasma volume effect have been calculated by simulation modelling. The related additional uncertainties are difficult to estimate, however the results of the previous calibration in 2013 have demonstrated that such uncertainties due to modelling are globally ⩽ ±3%. It has been found that the difference between KN1 response to DD neutrons and that to DT neutrons is within the uncertainties in the derived responses. KN2 has been calibrated using the 93Nb(n,2n)92mNb and 27Al(n,a)24Na activation reactions (energy thresholds 10 MeV and 5 MeV, respectively). The total uncertainty on the calibration factors is ±6% for 93Nb(n,2n)92mNb and ±8% 27Al(n,a)24Na (1σ). The calibration factors of the two independent systems KN1 and KN2 will be validated during DT operations. The experience gained and the lessons learnt are presented and discussed in particular with regard to the 14 MeV neutron calibrations in ITER.

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Technical preparations for the in-vessel 14 MeV neutron calibration at JET

Cited by 10 publications

References 5 publications

1997 JET DT experiments revisited—comparative analysis of DD and DT stationary baseline discharges

1997 JET DT experiments revisited—comparative analysis of DD and DT stationary baseline discharges

Research on the Influence of Cosolvent on the Determination of the Contamination Degree of Jet Fuel

14 MeV calibration of JET neutron detectors—phase 2: in-vessel calibration

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