A quick-response protective system for high power klystron with long pulse which is used in FEL injector based on RF linac is described. After a brief discussion of the requirements of a quick-response protective system for such a high power klystron with long pulse and a review of some methods which are still used at present, the basic principle, theoretical calculation and circuit design of this system are presented. The influence of change of klystron output power and of imperfect matching of the detector pair when the quick-response protective system is running can be elimitated by means of a method in which the voltage standingwave ratio(vswr)of the buncher is monitored and the coaxial thermionic diodes are used, which have nearly linear detection characteristics. Eventually, some test results are presented. It is shown that the system has short response time (2s) , adjuctable vswr (1.5-2.0) , simple structure and better antijamming performance. The system has been operated successfully for more than two years.

In order to perform the start-up of pressurized water reactor (PWR) for 300 MWe Qinshan Nuclear Power Plant, a pair of primary source rods with 210Po-Be neutron sources were made successfully. The total neutron emission was (3. 0 x108+5%) n/s (May 10, 1991). The dimensions of source rod were 10 mm in diameter and 3173 mm long. The research for source core (210Po-Be source) and source rod technology are described. A new production line of source rod has been established and approved source rod technology has been used. All examinations (including neutron emission,surface contamination, helium leak rate, weld detection, dimension measurement, linearity inspection, etc. ) showed that the quality of neutron source rods meets or exceeds the technical specifications of Inspecting and Accepting Outline of Primary Start-up Source Rods , prepared by the Qinshan Nuclear Power Plant and the Shanghai Institute of Nuclear Engineering Research Design. The 210Po-Be neutron source rods to start-up pressurized water reactor of Qinshan Nuclear Power Plant were utilized.

A 1.5 m tapered hybrid undulator has been designed and built for mid-infrared free electron laser experiments at CIAE. The undulator utilizes the REC-steel hybrid configuration. The magnetic gap and magnetic field taper can be continuously adjusted. The rms error of the peak field is less than 0. 53%. The electron trajectory deviation is around 0. 03 mm. The design of undulator, sorting of magnets in hybrid undulator using Simulated Annealing technique, the motion of electron beam in the ideal and measured magnetic field, magnetic field measurement technique and magnetic field adjustment are described.

Synchronizing hyperchaos is realized by the drive-respone relationship in the complex Lorenz-Haken system and its higher-order cascading systems for the first time. Controlling hyperchaos is achieved by the intermittent proportional feedback to all of the drive (master) system variables. The complex Lorenz-Haken system describes the detuned single-mode laser and is taken as a typical example of hyperchaotic synchronization to clarify our ideas and results. The ideas and concepts could be extended to some nonlinear dynamical systems and have prospects for potential applications, for example, to laser, electronics, plasma, cryptography, communication, chemical and biological systems and so on.

The transient behaviours of Miniature Neutron Source Reactor MNSR are analyzed and calculated with the reactor thermohydraulics RETRAN-02 [1] program and the reactor physics MARIA [2] program. The obtained event sequence and consequence from the calculation are compared with the experiments[3],The effective resonance integral for study on Doppler effect is taken into account. The reactivity temperature coefficient weighting factors are computed. The transient parameters related to reactor power peaking, coolant inlet temperatures, outlet temperatures and coolant mass flow, etc. are computed and compared with the experimental results.

In the preparation of Co, the reactions of 56Fe (d, n) 57Co and 56Fe (d, 2n) 57Co were selected by using 8.7 MeV deuteron to radiate natural iron which was electroplated on copper target. The methods of TBP-Benzene extraction and cation exchange were used for separating and purifying Co. The purity of the solution was checked by HPGe Y spectrometer and the total contents of impurities were below 0.2%. To prepare the source, silicon gel suspension was electrosprayed on VYNS thin film which was metalized by gold to form a proper source pad. Weighing balance was used to quantatively prepare the sources. Research on the ef-fecfs of the working gas pressure and the working voltage on the plateau curve was carried on by the presurized 4 coincidence equipment. Finally, efficiency extrapolation method was used to acurrately measure the specific activity of Co solution by means of changing the discrimination threshold. The total uncertainty is about 1.2% (3). It is shown that the solution is uniform,stable and accuracy with the reliable specific activity through the domestic comparison.

The preparation technology and characteristics of semiinsulating bulk single crystal GaAs surf ace-barrier detectors and single crystal CdTe sarface-barrier detectors are described. The spectroscopic performance of the detectors for Y-rays from 125I,241Am and 57Co at room temperature is given. The influence of the magnitude of toward resistive induced by ohmic contacts and of the surface passivation and aging in the fabrication process of sarface-barrier detectors on the performance of the detectors is discussed. Finally, the influence of the fabrication technology of ohmic contacts and selected materials,such as Ni-Ge-Au and In-Ge-Ag,on the performance of the detectors is also studied.

The developmental history of nuclear-agricultural sciences (NAS) in China was introduced. The proportion of NAS estimated by the scientometrics is about 1%-3% to the agricultural sciences, 3% to the nuclear science and technology, and below 0. 3% to the foundational life science, respectively. Citation indexes of NAS in China were compared with those of other scientific literatures domestic and abroad with bibliometrics. The main achievements and outcomes of NAS in China were described. In the past 25 years,the contribution of the NAS to the gross agricultual production in China was up to 250 hundred millions yuan RMB, corresponding to the ratio of 1: 31 of integrated scientific investments to the output . Comparison was made between the development of NAS in China and that abroad. Present situation and the prospect of the NAS were also discussed

In China, research on mutation breeding of ornamental plants was begun in the late 70's. In the past decade, about 40 plant species were tested, and hundreds of useful mutants were obtained. At least 63 mutant varieties have been produced, approved and released for cultivation in rose, chrysanthemum, canna, dahlia, bougainvillea and lotus. A rapid progress in methodology and technology of induced mutation breeding has been achieved, particularly in the selection of starting material , determination of suitable exposure and irradiation dose, expression and isolation of somatic mutation etc. In the future it is necessary to develop more plant species and mutation varieties, to improve the mutation breeding method and to raise the economic benefit. Along with the development of China's economy and improvement of people's living standard more and more new varieties of ornamental plants will be required. In view of the good beginning, rich germplasm resource and favorable conditions, the prospect of mutation breeding for ornamental plants in China is very encouraging.

The Zirconium Hydride Solid Zero Power Reactor built at China Institute of Atomic Energy is introduced. In the reactor Zirconium-hydride is used as moderator, plexiglass as reflector and U3O8 with enrichment of 20% as the fuel. Since its initial criticality, the physical characteristics and safety features have been measured with the result showing that the reactor has sound stability and high sensitivity, etc. It has been successfully used for the personnel training and for the testing of reactor control instruments and experiment devices. It also presents the special advantage for the pre-research of some applications.

Natural radionuclide contents were measured in various industrial waste slags in China by a low background HPGe r spectrometer and the radiological impact was estimated for some comprehensive utilization of these slags. Most waste slags can be used for building materials except for tailing and waste rock form nuclear industry.

A silver dichromate dosimeter was developed. With a spectrophotometer at wavelength of 350 nm, the molar linear absorption coefficient determined for Cr2O72- ions in perchloric acid solution is 315.9+1.5m2/mol. The G (-Cr2O72- value for this system is (3.75+0.02)x10-8 mol/J and the dose conversion factor K is 8403+42Gy. It is found that the G value slightly depends on the initial concentration of dichromate ions. The irradiation temperature coefficient of G is -0.22%C The total uncertainty is +4%(2) within the dose range from 0. 4 to 5 kGy.

The ammonia/hydrazine AVT (all-volatile treatment) can not prevent the erosion/corrosion of materials in two phase steam-water mixtures area of SG (steam generator) in PWR. According to the reports, the chemical addition agent, morpholine, which has less volatility can reduce the erosion/corrosion of materials in the two phase area of SG. The morpholine AVT has been used in the PWRs. This article is to introduce the optimum concentration of morpholine under the shutdown wet protection condition and operating condition of PWR. The experimental results show that under the shutdown wet protection condition in PWR SG secondary side the optimum concentration of morpholine is 200 ppm, and in operation condition the optimum concentration of morpholine is 25 ppm. The mechanism of anti-corrosion has been studied with the surface analysis technique of XPS (X-ray photoelectron spectroscopy). It shows that oxidation film and absorption film are formed on materials surface (A3, S271) when morpholine is used.

The methods of determining the superficial absorbed dose distributions in a water phantom by experiments and available theories are reported. The distributions of beta dose were measured by an extrapolation ionization chamber at definite depths corresponding to some superficial organs and tissues such as the radiosensitive layer of the skin, cornea, sclera, anterior chamber and lens of eyeball. The ratios among superficial absorbed dose D(0.07) and average absorbed doses at the depths of 1,2,3,4,5 and 6 mm are also obtained with Cross's methods. They can be used for confining the deterministic effects of some superficial tissues and organs such as the skin and the components of eyeball for weakly penetrating radiations.

By using l5N-labelling technique and Tn5-induced mutants the attachment of associative diazotroph Alcaligenes faecalis to intact rice plants was examined in vitro. Three distinguished modes of attachment of Alcaligenes faecalis : adsorption, anchoring and colonization were proposed by using 15N-labelling bacterial cells and Tn5-induced mutants. Che~mutants affected on adsorption, but not on anchoring. Exo- Che- mutant is deffective in both adsorption and anchoring. Exo~ or exo++ mutants are only deffective in anchoring. Effective colonization is benefit for establishment on the associative system. The data also indicated that EPS (ex-opolysaccharide) play rather important roles in the association between the host plant and bacteria.

It was showed that the dry weight and grain yield of rice were 2. 3%~12. 7% and 1.6%~11.8% higher respectively than those of urea applied alone when urea applied with cow slurry, rare-earth, maifanshi, calcium chloride and dicyandiamine (DCD). Among the treatments, BCD and maif anshi increased the nitrogen use efficiency of urea from 4. 3 kg grain/kg N applied when urea applied alone to 10. 7 kg grain and 12. 5 kg grain per kg N applied. It was shown from I5N tracing experiment that the nitrogen uptake efficiency of urea for rice when applied alone was 20. 6% while 25. 9, 26. 3, 24. 0, 28. 3 and 27. 9% respectively when applied with cow slurry , rare-earth, maifanshi, calcium chloride and DCD. Application of urea with above various materials contributed to a apparent effect on increase of nitrogen residue in soil and nitrogen loss (particularly in loss by air) from urea, among which, the best effect was obtained on nitrogen residue in soil from urea when applied with cow slurry and rare-earth, the residues were 30. 3% and 27. 3% of applied nitrogen respectively, and DCD could decrease the nitrogen loss of greatly, from 57. 5% of applied nitrogen when applied alone to 36. 3% of applied nitrogen. It was also showed that the difference of effect on kinetics of soil available nitrogen between one treatment and another was not significant, but significant difference existed in effect of different treatments on loss of soil nitrogen and soil nitrogen mineralization. Compared with labelled urea applied alone, application with cow slurry and DCD resulted in great decrease in loss of soil nitrogen and soil nitrogen mineralization while not apparent effect for application with rare-earth, calcium chloride and maifanshi.

A method to determine the hydrogen in sodium is introduced. The sodium sample, which is less than 7 g, is put into a thin iron capsule in argon atmosphere, the capsule is sealed by electron beam welding and heated to 700C in a vacuum system with pressure less than 10-5Pa, then the hydrogen released from the vacuum system can be determined. The determined limit by this method is 20-150ug and the standard deviation is 20%. This method uses electron beam welding to replace the argon arc welding and combines the off-line sampling with on-line measuring. It is an easier off-line measurement to determine hydrogen in sodium.

The cadmium ratio RCA and thermal neutron flux are usually measured in a re- ' actor. But its data process is rather complex. The results from same measured data differ by different existing process methods. The purpose of this work is to standardize data process in Ret and thermal neutron flux measures. A natural choice for this purpose is to derive a RCd formula based on standard average thermal activation cross section and resonance integral and to define related parameters or factors that provide an unique base for comparison between different measures in laboratories. These parameters or factors include Ec, Fm, Fm' and Gth' in thermal energy region due to upper truncated Maxwellian distribution and Ecd,FCd,Gr' and Sr in intermediate energy region. They are the function of multiple variables. The Au foil is used as an example to demonstrate their behaviors by chosen figures and tables which provide for practical data process by hand. The work also discusses limitation of RCA measurement in terms of so called available and optimum region and notes that Co and Mn foils have a much wider available region among Au, In, Mn, W and Co, the commonly used detector foils.

The ophthalmic radiotherapy dosimetry and some affecting factors are introduced. The distributions of absorbed doses to the main parts of a fresh eyeball such as the cornea, sclera, lens and anterior chamber, during the radiotherapy by using a 90Sr+90Y ophthalmic applicator are presented. An tissue-equivalent extrapolation ionization chamber was used in the dose measurement. The reasonable doses during ophthalmic radiotherapy for different depths have been obtained. Therefore, the absorbed dose to the lens, the most sensitive organ, can be given. These data are useful for radiation protection in ophthalmic radiotherapy.