Fluence, neutron

The linear relation between the PSL signal and neutron fluence was established to exist over three decades up to 6. lO cm. The IP-ND can be used as fast and efficient neutron monitors at rather low neutron fluxes. However, for neutron dosimetry individual IP-ND must be calibrated individually since their sensitiviy can differ from one plate to another. In Gd/film based direct NR the film fog below the exposure dose of about 8.10 cm is the limiting factor. 

Reactor power lOkW, exposure time 20 sec., neutron fluence 5.6 10+5 n/cm2 sec... 

The effect of fast neutron fluence on thermal conductivity and thermopower has been determined by Uher and Huang (70). For fluences to 3 x 1018 n/cm2 Tc decreases in Y-Ba-Cu-O to a temperature of 86 K, the thermal conductivity decreases and is without a peak above Tc and the thermopower starts from a negative value and approaches zero and becomes positive. As will be seen below the more usual value of thermopower is positive in the superconducting material but these authors note the variability dependent on sample preparation conditions. 

The water thickness measurement uncertainty due to neutron counting statistics can be calculated from Poisson counting statistics. For a random process, the standard deviation, Ah in the observed counts I is A/ = y7. The number of neutrons in the incident, or open beam, I0, is the product of the neutron fluence rate (cur2 s 1), integration time T (s), integration area A (cm2), and neutron detection efficiency, ip... 

KAERI is joining the PYCASSO experiment to investigate coating behaviour under irradiation (Groot, 2008). The objective of the experiment for KAERI is to analyse the porosity and property changes of a pyrolytic carbon buffer layer as a function of neutron fluence and temperature. Approximately 10 000 coated particles of four different coating layer densities were provided for PYCASSO. 

Figure 3. Fast neutron fluence dependence of conductivities for SrCeo Yboosfh-n specimens (a) with H at 384-401 and 484-519 K and (b) without H at 473 and 673 K, respectively.

Figures 3(a) and (b) show fast neutron fluence dependence of conductivities for the specimens (a) with and (b) without H at ionizing dose rates of 0.5 and 1.8 Gy/s, respectively. The irradiation temperatures for the specimens with and without H were 384-401 and 473 K at the first cycle and 484-519 and 673 K at the second cycle. It was found that the RIC increased with raising the irradiation temperature. Particularly, the RIC with H greatly corresponds to the change of the irradiation temperature. On the other hand, the RIC without H quickly decreased at the initial fluence and hereafter gradually as the fast neutron fluence increased, even if the irradiation temperature was constant.

The most stable graphites are the near-isotropic materials ". The effects of irradiation on the properties of graphite are governed by neutron energy, neutron fluence, temperature, temperature gradients, and structure and type of graphite used. The effects of irradiation are dimensional changes, reduction in thermal conductivity, and enhancement of creep rates. 

Abstract The Lifshitz - Slezov theory is applied to study the metastable states of the matrix damage clusters, MA, and the copper enriched clusters, CEC, in neutron irradiated steels. It was found that under irradiation conditions the CE Cs are at the Ostwald stage for a neutron fluence of about 0.0002 dpa. The time dependence of number density, MDn, is determined by summarizing all differential equations of the master equation for MA with neglecting of dimmers concentration in comparison with concentration of the single vacancies and subtraction of the number CEC that replace the MA, namely vacancy clusters, due to the diffusivity of copper and other impurity atoms to them. For binary Fe-0.3wt%Cu under neutron irradiation with dose 0.026, 0.051, 0.10 and 0.19 dpa the volume content of the precipitates from the SANS experiment is found to be about 0.229, 0.280, 0.237 and 0.300 vol% respectively. The volume fraction of CEC, in these samples is 0.195 vol% and the calculated volume fraction ofMA is 0.034, 0.085, 0.042 and 0.105 vol% for doses 0.026, 0.051, 0.10 and 0.19 dpa respectively. 

Gv is about 0.649-10 Y in study and Cvsat is about 10 atom respectively on Eq. (15). The upper limit of value to is about 15 hours for conditions in accordance with relations (11)-(16) and known from SANS upper limit of c mean maximal fluence. The corresponding neutron fluence... 

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