[en] Objective: To evaluate the imaging features of extratesticular scrotal masses in children. Methods: Imaging findings and clinical records were retrospectively analyzed in 10 children with extratesticular scrotal masses confirmed by surgery and pathology. Results: Benign lesions (7) included 2 fibrous hamartomas of infancy, 1 ectopic spleen tissue, 1 vascular malformation, 1 venous hemangioma, 1 abscess, and 1 cyst whereas malignancy was rhabdomyosarcoma in 3 children. All presented as painless scrotal masses with non-specific laboratory examinations. On CT and MRI, fibrous hamartoma of infancy appeared as heterogeneous scrotal masses near the inguinal canals with mild to moderate enhancement. The ectopic spleen tissue was a round, well-circumscribed nodule with intense homogeneous contrast enhancement superior to the left testis. Vascular malformation was seen as a mass with irregular shape under the tunica vaginalis with some flow voids on T₂-weighted imaging and early intense contrast enhancement. Venous hemangioma with thrombus formation exhibited a round well-defined mass with soft tissue density located above the testis and medial side of sperm cord, majority of which did not enhance. Abscess was a round heterogeneously hyperintense lesion on T₂- and diffusion-weighted imaging with ill-defined margins in the midline of the scrotum. Cyst showed typical round lesion with fluid density and no enhancement. Rhabdomyosarcomas demonstrated as heterogeneous markedly enhancing paratesticular masses, one of which invaded the testis and associated with distant metastasis. Conclusion: Most extratesticular scrotal lesions in children are benign, some of which have characteristic imaging appearance. Preoperative assessment with ultrasound and MRI is recommended. (authors)

[en] According to the material composition, flux spectrum measured and irradiation time, the dose and attenuation of products of NTD silicon system irradiated are calculated with ORIGEN and MCNP software. The different contributions of dose and decay time of product activation nuclide are analyzed. Meanwhile, the validation of calculation with the measurement of ionization chamber and estimation of shield thickness of hall show that the shield of NTD silicon system irradiated could meet the requirement of radiation protection and some suggestions are offered. (authors)

[en] The wall temperature of fuel element is an important factor affecting the integrity of the cladding. After the attenuation of secondary circuit water flow occurs during HFETR power operation, whether the inherent safety of HFETR can ensure that the fuel element temperature does not exceed the operating limit is the focus of this paper. Therefore, this paper established the HFETR loop system model based on RELAP5 program, simulated and analyzed the secondary circuit water flow attenuation of HFETR 80 MW in different degrees, and assumed that the operator did not intervene. The results show that the maximum wall temperature of the fuel element is 174.7 ∼ 174.8℃, which is less than the allowable limit (195℃), depending on the reactor protection system to shut down automatically within 30 minutes without human intervention. Even after the secondary circuit water is completely cut off and the operator does not conduct any operation within 30 minutes, the reactor is still in a safe state, which can avoid the safety risk introduced by human misoperation. (authors)

[en] This paper analyzes the basic requirements of the Monte Carlo burnup calculation for HFETR with MCNPX. The mathematical calculation model of HFETR is established by the Monte Carlo N-Particle extended code (MCNPX), and the MCNPX burnup interface program of HFETR is developed. The burnup and physical parameter of continuous three operation lifetime of HFETR are calculated, and the results are compared with neutron flux in the central position of the core and the net burnup calculated by traditional burnup calculation procedure ECP493, and compared with the actual control rod position of each burnup step. The calculation results are consistent with the actual operation data, with some deviations, mainly due to the imperfect model. Further study is required for the improvement of the precise of the reactor modeling in order to improve the calculation accuracy. (authors)

[en] In order to monitor the operation status of the main pump of the reactor, this paper designs a sound acquisition device for the project by using common tools such as pickup equipment and recording equipment from the point of view of simplicity and effectiveness, and collect the sound of the environment, motor end bearing and pump end bearing of four main pumps in different ways. The frequency spectrum of the collected sound signal is analyzed by MATLAB software, and the frequency and wavelength data are obtained. Then the operation status of the main pump is obtained by waveform comparison and spectrum data analysis. The results show that the sound frequencies of the four main pump bearings are mostly concentrated in the low frequency band, and there are abnormalities in the operation sounds of the 2# main pump and the 4# main pump bearings. The results are consistent with the actual situation. (authors)

[en] The leakage rate, related to the safety of reactor operation, is an important parameter for monitoring the operation of HFETR Research Reactor. While the current calculation of it is merely based on the change of the deaerator level rather than the power change of reactor, the level change of volume compensator and radiochemical sampling. Therefore, in order to improve the accuracy of leakage rate calculation, this paper will focus on the practical operation of HFETR Research Reactor and deeply analyze the reasons for dynamic change of total amount and operating data of RCP to correct and summarize the calculation of RCP leakage rate. (authors)

[en] This paper builds a primary loop thermal-hydraulic calculation model of High Flux Engineering Test Reactor (HFETR) based on Relap5, and the model is proved to be effective and accurate by an experiment in cold state. By simulating the full open fault of degassing flow control valve (DFCV) happened in running state with this model, the varieties of inlet pressure, outlet pressure and water level of volume compensator are obtained. The results of modeling show that fuel rods of HFETR are confirmed to be well submerged and cooled down, and HFETR remains safe. The reaction time for reactor operators and the reasonable water level of volume compensator are given by analyzing the calculation results, and an advice on DFCV working sate adjustment is proposed. (authors)

[en] Based on the improved droop control of the bidirectional converter controlled by the DC (direct current) side power quantity, a coordinated control scheme with energy storage is proposed. Not only can the two-way converter automatically and smoothly switch in the rectification, inverter, and idle modes, but also the energy storage device can perform coordinated control in the DC side idle mode to maintain the DC bus voltage stability. Using DC side power control, there is no need to switch control strategies to meet islanding and grid-connected modes. The simulation results show that improved droop control can reduce frequent actions of power electronic devices caused by small-range fluctuations in DC bus voltage and AC (alternating current) frequency. Coordinated control can make the DC bus voltage more stable, ensure stable operation of the AC and DC hybrid microgrid, and improve system reliability. (paper)