Vol.30,

Charged-particle diagnosis is an important aspect of laser-plasma experiments conducted at super-intense laser facilities. In recent years, Columbia Resin #39 (CR-39) detectors have been widely employed for detecting charged particles in laser-plasma experiments. This is because the CR-39 polymer does not respond to electromagnetic pulses (EMPs) or X-rays. This study presents a method for calibrating the relationship between particle energy and track diameter in a CR-39 detector (TasTrak®) using 3–8 MeV protons, 6–30 MeV carbon ions, and 1–5 MeV alpha particles. The particle tracks were compared under the manufacturer’s recommended etching conditions of 6.25 mol/l NaOH at 98 °C, and under the widely adopted experimental conditions of 6.25 mol/l NaOH at 70 °C. The results show that if the NaOH solution concentration is 6.25 mol/l, then the temperature of 70 °C is more suitable for etching proton tracks than 98 °C, and employing a temperature of 98 °C to etch alpha-particle and carbon-ion tracks can significantly reduce the etching time. Moreover, this result implies that C³⁺ ion or alpha-particle tracks can be distinguished from proton tracks with energy above 3 MeV by controlling the etching time. This calibration method for the CR-39 detector can be applied to the diagnosis of reaction products in laser-plasma experiments.

441

The time-domain calibration coefficient of a D-Dot sensor should be identical across various transverse electromagnetic (TEM) cells to comply with the IEEE Std 1309. However, in our previous calibration experiments, poor consistency was observed. The size of D-Dot sensors relative to TEM cells is considered the main reason for this poor consistency. Therefore, this study aims at determining the calibration coefficient of a D-Dot sensor. We calculate the theoretical coefficient as a reference. Practical calibration experiments involve the processing of TEM cells with three different sizes. To observe the response more clearly, corresponding models are constructed and numerical simulations are performed. The numerical simulations and experimental calibration are in good agreement. To determine the calibration accuracy, we quantify the accuracy using the relative error of the calibration coefficient. By comparing the coefficients obtained, it can be concluded that the perturbation error is about 15% when the relative size is over 1/3. Further, the relative size should be less than 1/5 to obtain a relative error below 10%.

549

The superconducting cyclotron SC200 is intended to generate a 200 MeV, 400 nA proton beam for future particle therapy. The internal hot-cathode-type Penning ionization gauge (PIG) ion source for the SC200 is designed for the generation of hydrogen ions. A brief description of the design of ion source and test bench, which are used in SC200, is given in this paper. The ion source has been verified on the test bench and the results indicated that the designed ion source meets the expected requirements. The lifetime of the filament exceeded 100 h in the test. In addition, the extraction voltage and the gas flow that influence the extracted ion current intensity have been tested in the experiment.

680

The SC200 proton therapy superconducting cyclotron was developed by ASIPP (Hefei, China) and JINR (Dubna, Russia). A measurement system was designed to assess the average radial component of the magnetic field (B_rav) with 15 search coils in the median plane. The winding differences of the search coils affect the measurement accuracy of the B_rav. Based on the electromagnetic induction principle, to measure the B_rav accurately, this paper focuses on the design and commissioning of the B_rav measurement system. The preliminary results confirm that the system design is reasonable and suitable. After testing the search coil at different speeds, the optimal speed was determined as 2.5 mm/s. The relative error was approximately 0.1% under the maximum radial component of the magnetic field B_r of 7 G. The measurement precision was up to 1.0×10^-3, which can provide the required measurement tolerance of 3–7 G for B_r in the median plane. The commissioning of the B_rav measurement system is an important step for B_r measurement. It can check and adjust the asymmetry of the superconducting coils (SCs).

436

The Rare Isotope Science Project (RISP) is a research complex consisting of a heavy-ion accelerator, which contains a front-end system, a super-conducting linear accelerator (SCL), an isotope separator online (ISOL) system, and an in-flight system. The original purpose of the post-linear-accelerator (post-linac) section was to accelerate either a stable driver beam derived from an electron cyclotron resonance (ECR) ion source, or an unstable rare-isotope beam from an ISOL system. The post linac lattice has now been redesigned using a novel and improved acceleration concept that allows the simultaneous acceleration of both a stable driver beam and a radioisotope (RI) beam. To achieve this, the post-linac lattice is set for a mass-to-charge ratio (A/q) that is the average of the two beams. The performance of this simultaneous two-beam acceleration is here assessed using two ion beams: ⁵⁸Ni⁸⁺ and ¹³²Sn²⁰⁺. A beam-dynamics simulation was performed using the TRACK and TraceWin codes. The resultant beam dynamics for the new RISP post-linac lattice design are examined. We also estimate the effects of machine errors and their correction on the post-linac lattice.

538

Annular centrifugal contactors (ACCs) have many advantages and are recognized as key solvent-extraction equipment for the future reprocessing of spent nuclear fuel (RSNF). To successfully design and operate ACCs for RSNF, it is necessary to understand the hydrodynamic characteristics of the extraction systems in ACCs. The phase ratio (R = V_aq/V_org, A/O) and liquid hold-up volume (V) of the ACC are important hydrodynamic characteristics. In this study, a liquid-fast-separation method was used to systematically investigate the effects of the operational and structural parameters on the V and R (A/O) of a φ20 ACC by using a 30%TBP/kerosene-HNO₃ solution system. The results showed that the operational and structural parameters had different effects on the V and R (A/O) of the mixing and separating zones of the ACC, respectively. For the most frequently used structural parameters of the φ20 ACC, when the rotor speed was 3500 r/min, the total flow rate was 2.0 L/h, and the flow ratio (A/O) was 1, the liquid hold-up volumes in the mixing zone and rotor were 8.03 and 14.0 mL, respectively, and the phase ratios (A/O) of the mixing zone and separating zone were 0.96 and 1.43, respectively.

450

Mass attenuation coefficients, effective atomic numbers, effective electron densities and Kerma relative to air for adipose, muscle and bone tissues have been investigated in the photon energy region from 20 keV up to 50 MeV with Geant4 simulation package and theoretical calculations. Based on Geant4 results of the mass attenuation coefficients, the effective atomic numbers for the tissue models have been calculated. The calculation results have been compared with the values of the Auto-Z_eff program and with other studies available in the literature. Moreover, Kerma of studied tissues relative to air has been determined and found to be dependent on the absorption edges of the tissue constituent elements.

461

The Dancoff correction is important in the calculation of the effective cross section of resonant isotopes in a heterogeneous system. Although the neutron current method is a simple and straightforward approach to estimate the Dancoff factor, its use is limited to the black Dancoff factor. In this paper, we expand the current method used to determine both the black and gray Dancoff factors. The method developed also relies on a neutron transport solver, where a fixed source on a fuel rod surface has an outward direction, a cosine distribution, and a constant shape. The detector is located on the surface of the rods to measure incoming and outgoing currents; therefore, there is no need to calculate the chord length and the development, validation and verification of the code can be omitted. The mathematical foundation of the suggested method is derived using the integral transport equation. The effects of the moderator and lattice configuration are followed by a sensitivity analysis of the Dancoff factor for several problems, including pressurized water reactor and cluster fuel assemblies. The maximum and average relative errors of the calculated results are approximately 0.3% and 0.05%, respectively.

467

The accelerator-driven sub-critical system (ADS) with a hard neutron energy spectrum was used to study transmutation of minor actinides (MAs). The aim of the study was to improve the efficiency of MA transmutation while ensuring that variations in the effective multiplication factor (k_eff) remained within safe margins during reactor operation. All calculations were completed using code COUPLE3.0. The sub-critical reactor was operated at a thermal power level of 800 MW and a mixture of mono-nitrides of MAs and plutonium (Pu) was used as fuel. Zirconium-nitride (ZrN) was used as an inert matrix in the fuel elements. The initial mass composition in terms of weight percentages in the heavy metal component (IHM) were 30.6 % Pu/IHM and 69.4 % MA/IHM. To verify the feasibility of this MA loading scheme, variations in k_eff, the amplification factor of the core, maximum power density and the content of MAs and Pu, were calculated over 6 refueling cycles. Each cycle was 600 days duration and therefore there were 3600 effective full power days. Results demonstrated that the effective transmutation support ratio of MAs was approximately 28, and the ADS was able to efficiently transmute MAs. The changes of other physical parameters were also within their normal ranges. It is concluded that the proposed MA transmutation scheme for an ADS core is reasonable.

510

Radiation damage is an important factor that must be considered while designing nuclear facilities and nuclear materials. In this study, radiation damage is investigated in graphite, which is used as a neutron reflector in the Tehran research reactor (TRR) core. Radiation damage is shown by displacement per atom (dpa) unit. A cross section of the material was created by using the SPECOMP code. The concentration of impurities present in the non-irradiated graphite was measured by using the ICP-AES method. In the present study the MCNPX code had identified the most sensitive location for radiation damage inside the reactor core. Subsequently, the radiation damage (spectral-averaged dpa values) in the aforementioned location was calculated by using the SPECTER, SRIM Monte Carlo codes and Norget, Robinson and Torrens (NRT) model. The results of "Ion distribution and quick calculation of damage" (QD) method groups had a minor difference with the results of the SPECTER code and NRT model. The maximum radiation damage rate calculated for the graphite present in the TRR core was 1.567×10^-8 dpa/s. Finally, hydrogen retention was calculated as a function of the irradiation time.

486

During the discharging of Tokamak devices, interactions between the core plasma and plasma facing components (PFCs) may cause exorbitant heat deposition in the latter. This poses a grave threat to the lifetimes of PFCs materials. An infrared (IR) diagnostic system consisting of an IR camera and an endoscope was installed on an Experimental Advanced Superconducting Tokamak (EAST) to monitor the surface temperature of the lower divertor target plate (LDTP) and to calculate the corresponding heat flux based on its surface temperature and physical structure, via the finite element method. First, the temperature obtained by the IR camera was calibrated against the temperature measured by the built-in thermocouple of EAST under baking conditions to determine the true temperature of the LDTP. Next, based on the finite element method, a target plate model was built and a discretization of the modeling domain was done. Then, a heat conduction equation and boundary conditions were determined. Finally, the heat flux was calculated. The new numerical tool provided results similar to those for DFLUX; this is important for future work on related physical processes and heat flux control.

526

In this study, thermal-hydraulic parameters inside the containment of a WWER-1000/v446 nuclear power plant are simulated in a Double Ended Cold Leg (DECL) accident for short and long times (by using CONTAIN 2.0 and MELCOR 1.8.6 codes) and the effect of the spray system as an Engineering Safety Feature (ESF) on parameters mitigation are analyzed with the former code. Along with the development of the accident from Design Basis Accident (DBA) to Beyond Design Basis Accident (BDBA), the zircaloy-steam reaction becomes the source of in-vessel hydrogen generation. Hydrogen distribution inside the containment is simulated for a long time (using CONTAIN and MELCOR) and the effect of recombiners on its mitigation are analyzed (using MELCOR). Thermal-hydraulic parameters and hydrogen distribution profiles are presented as the outcome of the investigation. By activating the spray system, the peak points of pressure and temperature occur in the short time and remain below the maximum design values along the accident time. It is also shown that recombiners have a reliable effect on reducing the hydrogen concentration below flame-propagation limit in the accident localization area. The parameters predicted by CONTAIN and MELCOR are in good agreement with the Final Safety Analysis Report. The noted discrepancies are discussed and explained.

753

The Fluoride Volatility Method (FVM) is a technique tailored to separate uranium from fuel salt of molten salt reactors (MSR). A key challenge in R&D of the FVM is corrosion due to the presence of molten salt and corrosive gases at high temperature. In this work, a frozen-wall technique was proposed to produce a physical barrier between construction materials and corrosive reactants. The protective performance of the frozen-wall against molten salt was assessed using FLiNaK molten salt with introduced fluorine gas, which was regarded as a simulation of the FVM process. SS304, SS316L, Inconel 600 and graphite were chosen as the test samples. The extent of corrosion was characterized by an analysis of weight loss and scanning electron microscope (SEM) studies. All four test samples suffered severe corrosion in the molten salt phase with the corrosion resistance as: Inconel 600 > SS316L > graphite > SS304. The presence of the frozen-wall could protect materials against corrosion by molten salt and corrosive gases, and compared with materials exposed to molten salt, the corrosion rates of materials protected by the frozen–wall were decreased by at least one order of magnitude.

681

The Hefei Light Source-II (HLS-II) is a vacuum ultraviolet synchrotron light source. The Personnel Safety System (PSS), which is a personnel access control system, is a crucial part of the HLS-II, as it protects the staff and users at HLS-II from radiation damages. The prior version of HLS-II PSS was based on an access control system called SiPass. This lacked the personnel management function. Meanwhile, as the prior PSS is a turn-key system, it was not effective for sharing information. To overcome these drawbacks, the novel design of PSS for HLS-II is proposed based on the Siemens redundant programmable logic controller (PLC) under the Experimental Physics and Industrial Control System. The proposed PSS consists of a safety interlock system, access control system, and a radiation monitoring system. The safety interlock system is used to define the interlock logic. The access control system is designed to restrict the access of staff and users at HLS-II, and to provide a personnel management function. The radiation monitoring system is used to monitor the radiation dose rate in both the light source and the surrounding areas. This paper details the architecture and the specific design of the novel PSS. The offline test results demonstrate that the proposed system has achieved the design objectives.

461

508

535