Vol.18,

575

This paper introduces the injection and extraction control system design for SSRF, which is a distributed control system aimed at stability and reliability of the pulse power supplies, PPS (Personnel Protection System) and MPS (Machine Protection System). The hardware environment is mainly based on PLC (Programmable Logic Controller), and ARM (Advanced RISC Machine) is also applied for studying stability of the power supplies. WinCC and EPICS (Experimental Physics and Industrial Control System) have been selected as the platforms of SCADA (Supervisory Control and Data Acquisition). For unifying the interfacing to the control computer, all front-end equipments are connected via Industrial Ethernet.

548

A mathematical method was developed to calculate the yield, energy spectrum and angular distribution of neutrons from D(d,n)³He (D-D) reaction in a thick deuterium-titanium target for incident deuterons in energies lower than 1.0MeV. The data of energy spectrum and angular distribution were applied to set up the neutron source model for the beam-shaping-assembly (BSA) design of Boron-Neutron-Capture-Therapy (BNCT) using MCNP-4C code. Three cases of D-D neutron source corresponding to incident deuteron energy of 1000, 400 and 150 keV were investigated. The neutron beam characteristics were compared with the model of a 2.45 MeV mono-energetic and isotropic neutron source using an example BSA designed for BNCT irradiation. The results show significant differences in the neutron beam characteristics, particularly the fast neutron component and fast neutron dose in air, between the non-isotropic neutron source model and the 2.5 MeV mono-energetic and isotropic neutron source model.

672

A previous analytical model for N-member radionuclide decay chains has been extended to include the effect of radionuclide sorption with groundwater colloids. Published distribution coefficients were employed in the nuclide decay chain to illustrate the present model. The colloid concentration was assumed constant in time and space owing to equilibrium between colloid generation and sedimentation by chemical and/or physical perturbations. Furthermore, the diffusion of colloids into the rock matrix was ignored because the diameter of colloid is relatively large and colloids and fracture surfaces are like-charged. The results indicated that colloids could facilitate the transport of radionuclides and the large adsorbability of nuclides with colloids enlarged the effect of acceleration by colloids. The influence of colloids on the radionuclide transport was expected to be crucial to the actinides with large adsorbability; however, the present results revealed that the low-adsorbing nuclides whose parent nuclides have large capability of sorption could be also facilitated significantly by colloids indirectly. Therefore, the role of colloids played in the transport of the radionuclides decay chain should be assessed carefully in the radioactive waste disposal. The analytical method presented herein is helpful to verify/validate further complex far-field models.

776

In this work, TTHMP was synthesized and labelled with ^117m Sn. The preparation conditions, stability and lipophilicity of ^117mSn(IV)-TTHMP were investigated. Biodistribution of the complex in rabbits and mice was studied. It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of ^117mSn(IV)-TTHMP. It was also found that ^117mSn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air. ^117mSn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals. This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.

587

Formation of nuclear tracks in solids has been described as a thermal spike as well as a Coulomb explosion spike. Here, formation of nuclear tracks is described as a compound spike including partial roles of both thermal and Coulomb explosion spikes in track formation. Fractional roles of both spikes depend on atomic and electronic structure of a track detector and deposited energy density in the track detector by the incident charged particle. Behavior of the cylindrical zone along the path of the incident particle is described mathematically in terms of bulk and individual atomic flow or movement. Defect structure of the latent nuclear tracks is described and conditions of continuity and discontinuity of latent tracks are evaluated and discussed. This paper includes mathematical description, analysis and evaluation of the nuclear track formation issue in the light of published experimental and theoretical results, which are useful for users of nuclear track detection technique and researchers involved in ion beam induced materials modification and ions implantation in semiconductors.

561

Characteristic gamma rays of 100 keV to about 6 MeV from different elements stimulated by neutrons have been applied to diagnosis biological imaging. In this paper, BGO detectors are used for the spectrum simulation. Signals from a single crystal and after correction are both obtained, and the energy spectrum summing adjacent signals seems possible to achieve excellent energy resolution for such high-energy photons. Some ideal suppositions are introduced and some other information, such as spatial resolution and difficult electronics, should be considered after this correction.

2128

Cadmium zinc telluride (CZT) is a preferred material for X-ray and gamma-ray detector. Thanks to the relatively high atomic number, high density and wide band-gap, CZT detector possesses sharp energy resolution and high detection efficiency without cryogenic cooling. We have developed a CdZnTe detector with an energy resolution of 3.45% (FWHM) at 59.54 keV at room temperature, and it is used for X-ray fluorescence analysis. In this paper, leakage current, energy resolution and long term stability of the CZT detector are discussed.

551

In order to compare the dosimetric properties of two kinds of solid state detectors used for monitoring external exposures, experiments were performed for the GD-300 series of radiophotoluminescent glass detectors (RPLGD) and the GR-200 series of thermoluminescent detectors (TLD). X-rays and ¹³⁷Cs and ⁶⁰Co γ-rays were used to irradiate the RPLGDs and TLDs, their dose linearity, uniformity/reproducibility of signal, fading effect and energy dependence were compared. Both kinds of the detectors have generally good dosimetric properties. The dose linearity and energy dependence of the GD-351 dosimeters and the TLDs are nearly the same, but the RPLGD is much better than the TLD in terms of the uniformity and fading effect.

919

Monitoring results of gamma dose rate level in 1992~2004 in the ambient environment of the Qinshan Nuclear Power Plants (QNPP) Base, the northeast of Zhejiang Province, are reported in this paper. It is shown that the gamma dose rate of five monitoring sites of 2.5 km to QNPP Base is 84~113 nGy/h, with an average of 96 nGy/h in the 13 years. The average value is close to the background level of 93 nGy/h prior to operation of the QNPP Base, and is lower than the monitoring result of 101 nGy/h at the reference site in Hangzhou City. Within 50 km from the QNPP Base, the cumulative dose rate of the thermoluminescent dosimeter (TLD) is 90 nGy/h, which is lower than the background level of 111 nGy/h.

946

Soil samples in and around salt field area have been analyzed for natural radioactivity concentration using gamma ray spectrometer. The activity concentration for ²³²Th, ²³⁸U and ⁴⁰K are ranged from 27.88 to 45.27 Bq/kg, from BDL to 13.30 Bq/kg, and from 135.54 to 381.28 Bq/kg, respectively. The measured activity concentrations for these radionuclides were compared with world average activity of soil. The average activity concentration of ²³²Th in the present study is 1.19 times higher than world median value while the activity of ²³⁸U and ⁴⁰K is found to be lower. The absorbed dose rates due to these radionuclides were calculated. The average absorbed gamma dose rate due to the presence of ²³²Th, ²³⁸U and ⁴⁰K in soil samples is 36.99 nGy·h^-1. These results indicate no radiological anomaly. The data presented in this study will serve as a base line survey for primordial radionuclides concentration in the study area.

774

An experiment facility for observing low-temperature molten tin alloy droplet into water was established to investigate mechanisms of vapor explosion occurring in severe accidents of a fission nuclear reactor. The vapor explosion behaviors of the molten material were observed by a high-speed video camera and the vapor explosion pressures were recorded by a pressure transducer mounted under the water surface. The results showed that the pressure reached a peak value when the molten metal temperature was 600℃–650℃, and the coolant temperature had an obvious decreasing effect on the droplet breakups. A model for single droplet fuel/coolant interaction is proposed. It considers that in the case of Rayleigh-Taylor instability, the coolant that jets from opposite direction penetrates into the fuel and the vapor explosion occurs because of the rapid evaporation. This model explained the effect of metal droplet temperature and coolant temperature on vapor explosion.

656