Fitness for duty in the nuclear power industry. Annual summary of program performance reports

This report summarizes the data from the semiannual reports on fitness-for-duty programs submitted to the NRC by utilities for two reporting periods: January 1-June 30, 1995, and July 1 -December 31, 1995. During 1995, licensees reported that they had conducted 150,121 tests for the presence of illegal drugs and alcohol. Of these tests, 1,476 (.98%) were confirmed positive. The majority of positive test results (1, 122) were obtained through pre-access testing. Of tests conducted on workers having access to the protected area, there were 180 positive tests from random testing and 139 positive tests from for-cause testing. Follow-up testing of workers who had previously tested positive resulted in 35 positive tests. For-cause testing resulted in the highest percentage of positive tests; about 18 percent of for-cause tests were positive. This compares with a positive test rate of 1.41 percent of pre-access tests and .27 percent of random tests. The positive test rate for workers with unescorted access was .50 percent. Positive test rates also varied by category of worker. When all types of tests are combined, short-term contractor personnel had the highest positive test rate at 1.44 percent. Licensee employees and long-term contractors had lower combined positive test rates (.34% and .40%, respectively). Of the substances tested, marijuana was responsible for the highest percentage of positive test results (53.08%), followed by cocaine (24.24%) and alcohol (17.17%). The overall positive test rate for 1995 (.98%) was higher than in 1994 (.84%). Several factors had an impact on the positive test rate across test categories for 1994 and 1995 compared to previous years. These factors include the NRC`s reduction in the mandatory random testing rate from 100 percent to 50 percent, effective in 1994, and initiatives by licensees such as lowered marijuana screening cutoff levels and reported improvements in licensees ability to detect subversion of the process

A comparison of the cylinder power and axis resulting from the modification of the gross opthalmometer cylinder by combining it with the hypothetical internal astigmatism with the clinically acceptable cylinder habitually worn by the subject

A comparison of the cylinder power and axis resulting from the modification of the gross opthalmometer cylinder by combining it with the hypothetical internal astigmatism with the clinically acceptable cylinder habitually worn by the subjec

Theory of vortex excitation imaging via an NMR relaxation measurement

The temperature dependence of the site-dependent nuclear spin relaxation time T_1 around vortices is studied in s-wave and d-wave superconductors.Reflecting low energy electronic excitations associated with the vortex core, temperature dependences deviate from those of the zero-field case, and T_1 becomes faster with approaching the vortex core. In the core region, T_1^{-1} has a new peak below T_c. The NMR study by the resonance field dependence may be a new method to prove the spatial resolved vortex core structure in various superconductors.Comment: 5 pages, 3 figure

Photoconductive Detectors with Fast Temporal Response for Laser Produced Plasma Experiments

Processes during laser plasma experiments typically have time scales that are less than 100 ps. The measurement of these processes requires X-ray detectors with fast temporal resolution. We have measured the temporal responses and linearity of several different Xray sensitive Photoconductive Detectors (PCDs). The active elements of the detectors investigated include both diamond (natural and synthetic) and GaAs crystals. The typical time responses of the GaAs PCDs are approximately 60 ps, respectively. Some characterizations using X-ray light from a synchrotron light source are presented

Zeeman Perturbed 63^{63}Cu Nuclear Quadrupole Resonance Study of the Vortex State of YBa2_2Cu3_3O7−δ_{7-\delta}

We report a $^{63}$Cu nuclear quadrupole resonance (NQR) study of the vortex state for an aligned polycrystalline sample of a slightly overdoped high-$T_c$ superconductor YBa$_2$Cu$_3$O$_{7-\delta}$ ($T_{c}\sim$92 K) at a low magnetic field of 96 mT along the c axis, near a lower critical field $H_{c1}$. We observed the frequency distribution of the nuclear spin-lattice relaxation time $^{63}T_1$ in the Zeeman-perturbed $^{63}$Cu NQR spectrum below $T_c$. The characteristic behavior of 1/$^{63}T_1$, taking the minimum values with respect to temperature and frequency, indicates the significant role of antiferromagnetic spin fluctuations in the Doppler-shifted quasiparticle energy spectrum inside and outside vortex cores.Comment: 4 pages, 4 figure

Site-selective nuclear magnetic relaxation time in a superconducting vortex state

The temperature and field dependences of the site-selective nuclear spin relaxation time T_1 around vortices are studied comparatively both for s-wave and d-wave superconductors, based on the microscopic Bogoliubov-de Gennes theory. Reflecting low energy electronic excitations associated with the vortex core, the site selective temperature dependences deviate from those of the zero-field case, and T_1 becomes faster with approaching the vortex core. In the core region, T_1^{-1} has a new peak below the superconducting transition temperature T_c. The field dependence of the overall T_1(T) behaviors for s-wave and d-wave superconductors is investigated and analyzed in terms of the local density of states. The NMR study by the resonance field dependence may be a new method to probe the spatial resolved vortex core structure in various conventional and unconventional superconductors.Comment: 14Pages, 26 figures, revte

Photoconductive Detectors with Fast Temporal Response for Laser Produced Plasma Experiments.

Processes during laser plasma experiments typically have time scales that are less than 100 ps. The measurement of these processes requires X-ray detectors with fast temporal resolution. We have measured the temporal responses and linearity of several different X-ray sensitive Photoconductive Detectors (PCDs). The active elements of the detectors investigated include both diamond (natural and synthetic) and GaAs crystals. The typical time responses of the GaAs PCDs are approximately 60 ps, respectively. Some characterizations using X-ray light from a synchrotron light source are presented

11^{11}B NMR study of pure and lightly carbon doped MgB2_2 superconductors

We report a $^{11}$B NMR line shape and spin-lattice relaxation rate ($1/(T_1T)$) study of pure and lightly carbon doped MgB$_{2-x}$C$_{x}$ for $x=0$, 0.02, and 0.04, in the vortex state and in magnetic field of 23.5 kOe. We show that while pure MgB$_2$ exhibits the magnetic field distribution from superposition of the normal and the Abrikosov state, slight replacement of boron with carbon unveils the magnetic field distribution of the pure Abrikosov state. This indicates a considerable increase of $H_{c2}^c$ with carbon doping with respect to pure MgB$_2$. The spin-lattice relaxation rate $1/(T_1T)$ demonstrates clearly the presence of a coherence peak right below $T_c$ in pure MgB$_2$, followed by a typical BCS decrease on cooling. However, at temperatures lower than $\approx 10$K strong deviation from the BCS behavior is observed, probably from residual contribution of the vortex dynamics. In the carbon doped systems both the coherence peak and the BCS temperature dependence of $1/(T_1T)$ weaken, an effect attributed to the gradual shrinking of the $\sigma$ hole cylinders of the Fermi surface with electron doping.Comment: 8 pages, 6 figures, submitted to Phys. Rev.