Hiroshi Seki

Abnormal Event Identification in Nuclear Power Plants Using a Neural Network and Knowledge Processing

The combination of a neural network and knowledge processing have been used to identify abnormal events that cause a reactor to scram in a nuclear power plant. The neural network recognizes the abnormal event from the change pattern of analog data for state variables, and this result is confirmed from digital data using a knowledge base of plant status when each event occurs. The event identification method is tested using test data based on simulated results of a transient analysis program for boiling water reactors. It is confirmed that a neural network can identify an event in which it has been trained even when the plant conditions, such as fuel burnup, differ from those used in the training and when the analog data contain white noise. The network does not mistakenly identify the nontrained event as a trained one. The method is feasible for event identification, and knowledge processing improves the reliability of the identification.

OPTICAL ABSORPTION AND ELECTRON SPIN RESONANCE SPECTRA OF CATION RADICALS OF DIMERIC CHLOROPHYLL a IN LOW‐TEMPERATURE MATRICES

Abstract— A chlorophyll (Chl) a solution in 3‐methylpentane at 77 K exhibits an absorption spectrum with a distinct peak at 706 nm in the red‐band region. The formation of the 706 nm absorbing species (S706) was reversible with respect to temperature change; no chemical change was observed. γ‐Irradiation of the rigid 3‐methylpentane solution at 77 K yields an absorption spectrum which can be ascribed to S706+ and S706−. When carbon tetrachloride, an electron scavenger, was added to the solution, the absorption of S706+ survived, which has peaks at 850 and 956 nm. It is assumed that the S706 is hydrogen‐bonded dimeric Chi a, which may be regarded as a model of P700 in photosynthesis. Cation radicals of monomeric Chi a were formed in a γ‐irradiated sec‐butyl chloride solution at 77 K, and an absorption spectrum with peaks at 730 and 813 nm was recorded. ESR spectra of the cation radicals of S706 and monomeric Chi a are of a similar shape but their linewidths are 7.5 and 11.0 Gauss, respectively. The linewidth narrowing observed for S706+ is clear evidence for the assumption that S706 is dimeric Chi a. Comparison was made of the absorption spectrum of S706+ with the light‐induced spectrum of P700 reported earlier.

Radiation Chemical Studies with Cyclotron Beams, (I) Fricke Solution

Systematic studies on the LET effect in the radiolysis of organic liquids have been initiated using various types of heavy ions accelerated by cyclotron. First, the effects of differences in irradiation conditions, in particular beam current, stirring speed and concentration of solutes have been examined. Aerated aqueous ferrous sulfate solutions (Fricke solutions) were subjected to irradiation by protons and He ions of various energies, to take advantage of the well-established reaction mechanism of the system. Experimental results obtained under various conditions were analyzed on the basis of the diffusion kinetics model. It was revealed that meticulous care must be taken to control the experimental conditions in studying radiolysis with heavy ions. The oxidation yields of ferrous ions were also determined as a function of linear energy transfer.

The oxidation of ferrocytochrome c by Br−2, (SCN)−2, N3 and OH radicals studied by pulsed-electron and γ-ray radiolysis

The reactions of ferrocytochrome c with Br2-, (SCN)2-, N3 and OH radicals were followed by measuring the change in the optical spectra of cytochrome c on gamma-irradiation as well as the rate of change of absorbance upon pulse irradiation. Ferrocytochrome c is oxidized to ferricytochrome c by Br2-, (SCN)2- or N3 radical with an efficiency of about 100% through a second-order process in which no intermediates were observed. The rate constants in neutral solutions at I = 0.073 are 9.7 . 10(8) M-1 . s-1, 7.9 . 10(8) M-1, 1.3 . 10(9) M-1 . s-1 for the oxidation by Br2-, (SCN)2- and N3 radicals, respectively. The rate constants do not vary appreciably in alkaline solutions (pH 8.9). The ionic strength dependence was observed for the rate constants of the oxidation by br2- and (SCN)2-. Those rate constants estimated on the assumption that the radicals react only with the amino acid residues with the characteristic steric correction factors were less than one-tenth of the observed ones. These results suggest that the partially exposed region of the heme is the probable site of electron transfer from ferrocytochrome c to the radical. Hydroxyl radicals also oxidize ferrocytochrome c with a high rate constant (k greater than 1 . 10(10) M-1 . s-1), but with a very small efficiency (5%).

The cleavage of the carbon-cobalt bond in vitamin B1 2 and coenzyme B1 2 by reduction with electrons in γ-irradiated frozen solutions

Abstract The one-electron reduction of vitamin B1 2 and its coenzyme has been studied by γ-irradiating the frozen methanolic solutions of these compounds. A new optical absorption spectrum was obtained by γ-irradiation of aqueous methanol solution of vitamin B1 2 at 77°K; this spectrum changed by slight warming to that of B1 2 r. ESR spectra were also recorded. The ESR signal at g ≈ 2.3 for the irradiated solution at 77°K was ascribed to the vitamin B1 2 anion, in which an unpaired electron is localized in the σ★ orbital of the cobalt-ligand bond. Upon slight warming the ESR signal changed to that of B1 2 r. In contrast to the vitamin, the ESR spectrum of irradiated coenzyme B1 2 solution in C2 H3 O2 H3 + 2H2 O at 77°K showed no signal due to a paramagnetic cobalt complex but an asymmetric signal of g ≈ 2.0, which is attributable to an organic radical presumably derived from the adenosyl group. The optical spectrum indicates the formation of B1 2 s (diamagnetic) by the CoC bond cleavage. Upon slight warming the optical and ESR spectra changed to those ascribed to B1 2 r. The present study thus revealed that the one-electron reduction of vitamin B1 2 and its coenzyme B1 2 gives rise to the heterolytic cleavage of the CoC bonds by the selective attack of electrons, and the former produces B1 2 r and the latter, B1 2 s.

Laser photolysis studies of copper (II) porphyrins in 2-methyltetrahydrofuran at 77 K. Optical absorption and lifetimes of the excited states

Abstract The transient spectra of copper (II) octaethylpophyrin and copper (II) tetraphenylporphyrin in MTHF at 77 K are attributed to the quartet state oil the basis of an analysis of the decays of the luminescence and transient spectra.

Laser photolysis studies of the anthracene dimer produced by photolytic dissociation of dianthracene in 2-methyltetrahydrofuran solution at 77 K

Abstract The absorption spectrum of the anthracene excimer as well as the triplet species was observed by laser photolysis of the anthracene dimer produced by UV photolysis of dianthracene in 2-methyltetrahydrofuran solution at 77 K.

Drawing data refining system according to plant product life cycle

Abstract Engineering data warehouse has been developed in order to integrate and exchange data through lifecycle of process plants. Based on a common information model, CAD data translators from 2D drawings and 3D models were built and their browsers have been also built. In order to adopt every task in the plant related work with its design data, such as process and instrumentation 2D drawings, a continuous refining system for drawing data has been built. With this system, a mechanism for keeping data consistency between actual project data and design data has been considered.