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Four fluoride fuel salt samples (78LiF-22ThF4) in graphite crucibles were irradiated in the HFR Petten for a duration of 508 Full Power Days under the name SALIENT-01 (SALt Irradiation ExperimeNT). Goal of the experiment was to gain experience with the design of liquid salt experiments and the handling of the salts before and after irradiation. Specific research goals for SALIENT-01 are (i) to confirm claims of good fission product retention in the salt, (ii) to obtain size distributions for noble metal particles using Transmission Electron Microscopy and (iii) to assess possible interactions between fuel salt and fine-grained nuclear graphite, as well as possible uptake of fission products by the graphite. Here the design and irradiation history of the experiment are discussed together with plans for post-irradiation examinations. Limitations in representativeness of this experiment and capsule irradiations in general are discussed as well as follow-up actions to improve the quality of future irradiations.

Representative irradiated graphite properties are essential for the successful design, licensing and long term operation of a graphite moderated reactor. These properties are acquired from irradiation programs that are executed in different Materials Test Reactors around the world. Recently, the Nuclear Research and consultancy Group (NRG) has completed a graphite irradiation creep program by the name ACCENT to support long term operation of Advanced Gas-cooled Reactors in the UK. In a series of 4 irradiation steps, paired graphite specimens are irradiated at a temperature of 440 °C under loaded and non-loaded conditions. By using a modular design with pressurized bellows, a load of 5 or 10 MPa is applied to the specimens. Characterization of the graphite specimens is performed before, between and after the irradiation steps to generate graphite property curves in a range of 0 to 14 DPA. This paper describes the different design, construction and operational aspects of graphite irradiation (creep) facilities that are fundamental to successfully acquire representative irradiation data. It will be demonstrated how these different aspects are controlled for the ACCENT graphite irradiation creep facility.

The synthesis and characterization of the monopyridine complexes of ethylzinc hydride and phenylzinc hydride are described. On treatment with TMED these complexes are converted into R2Zn3H4. TMED species through a combination of ligand-exchange and disproportionation. The formation of organozinc hydrides from ω-functionally-substituted diorganozinc compounds is only successful when the intramolecular coordination in these starting materials is weak and easily broken by pyridine. The results of these investigations are used as a basis for a discussion of the factors governing the formation of stable organozinc hydrides. The RZnH.py complexes easily reduce ketones and aldehydes, but no unusual stereoselectivity was observed in the reduction of substituted cyclohexanones. EtZnH.py reacts with an excess of pyridine with formation of the bis pyridine complex of ethyl(1,4-dihydro-1-pyridyl)zinc, a soluble compound, which is monomeric in benzene. The corresponding phenylzinc complex, however, cannot be isolated; disproportionation to Ph2Zn .2py and the bis pyridine complex of bis(1,4-dihydro-1-pyridyl)zinc occurs.

Ethyl (ω-dimethylamino-1 -alkynyl)zinc compounds and bis (ω-dimethylamino-l-alkynyl)zinc compounds were prepared by metalation of the dimethyl amino alkynes HCC(CH 2 ) n ,NMe 2 ( n = 1–4) with diethylzinc and diphenylzinc. All compounds show oligomeric or polymeric association in benzene, the degree of association being dependent on the value of n . The presence of coordinating dimethylamino groups and/or bridging alkynyl groups was established by IR and NMR spectroscopy. Plausible structures for all compounds, based on spectroscopic and molecular weight data, are presented.

The arylation of carbonylgold chloride with diarylzinc compounds yields either triarylgoldzinc or diarylgoldzinc chlorides, depending on the reactant ratio and the nature of the aryl group. The same reactions with diphenylcadmium and diphenylmercury yield exclusively diphenylgoldcadmium chloride and diphenylgoldmercury chloride, respectively. The reactions of the products with N , N , N ′, N ′-tetramethylethylenediamine and triphenylphosphine were studied. Phenylgold has been obtained as a very unstable solid from diphenylgoldzinc chloride and diphenylgoldmercury chloride.

The synthesis and characterization of 1,4-dihydro-1-pyridylzinc and -magnesium complexes are described. Zinc hydride and magnesium hydride dissolve in and react with pyridine, and the reaction has been studied in detail in the case of zinc hydride. Evaporation of the solvent after 1–2 hours at 0°C yielded a product containing pyridine, a 1,4-dihydropyridyl moiety and zinc hydrogen bonds, and two alternative structures are proposed for this complex. When the reaction was carried on for a long period, a yellow precipitate began to separate after about 40 hours, and reaction was complete after 7 days. The yellow product was identified as the pyridine complex of bis(1,4-dihydro-1-pyridyl)zinc. The corresponding magnesium complex was obtained from the reaction between magnesium hydride and pyridine for 50 hours at room temperature.

Bis(1,4-dihydro-1-pyridyl)zinc and -magnesium complexes are mild reducing agents. These compounds contain metal-bound 1,4-dihydropyridyl groups which act as hydride donors. In this paper we report the reactions of these new reagents with compounds which contain a carbonyl group, viz. ketones, aldehydes, enones and carboxylic esters. The stereochemistry of the reduction of cyclic ketones by bis(1,4-dihydro-1-pyridyl)zinc and -magnesium complexes has been studied. In reactions with carboxylic esters no reduction was observed; instead, acylation of one of the 1,4-dihydropyridyl groups bound to the metal took place yielding (novel) N-acyl-1,4-dihydropyridines. The scope of the reductions by the bis(1,4-dihydro-1-pyridyl)metal complexes is outlined, and the possible biological implications of the study are discussed.

Ethyl(4-dimethylamino-1-butynyl)zinc was prepared by metalation of 1-dimethylamino-3-butyne with diethylzinc in benzene. Bis(4-dimethylamino-1-butynyl)zinc was synthesized similarly from diphenylzinc and two equivalents of the acetylenic amine. Both compounds are trimeric in benzene; structures are proposed on the basis of the spectroscopic evidence.

The pyridine complexes of ethyizinc hydride and phenyLzinc hydride were prepared by treatment of the corresponding diorganozinc compounds with zinc hydride and two equivalents of pyridine in THF or benzene solution. Both complexes of the type RZnH·py, which were characterized by NMR spectroscopy, are trimeric in benzene solution.

The synthesis and NMR spectroscopic properties of some methyl-substituted 1-methyl-1,4-dihydropyridines are described.

Aromatic nitrogen heterocycles, e.g. quinoline, 2,2‘-bipyridyl and 1,10-phenanthroline, are reduced in a uniquely specific and selective way by the bispyridine complexes of bis(1,4-dihyro-1-pyridyl)zinc and bis(1,4-dihydro-1-pyridyl)magnesium. The reactions occur by hydrogen transfer from the metal-bound 1,4-dihydropyridyl moieties to the substrates and yield zinc or magnesium salts of the 1,4-dihydroazaaromatic derivatives. Upon hydrolysis, the 1,4-dihydroazaaromatic compounds are liberated from the metal ions. The isolation and purification of several of the (novel) reduced compounds, e.g. 1,4-dihydroquinoline and 1,4-dihydro-1,10-phenanthroline, are described.