Norman C. Rasmussen

APPLICATION OF FOURIER TRANSFORMS TO THE ANALYSIS OF SPECTRAL DATA.

Abstract A computer method for automatically identifying the peaks in complex spectra and determining their centers and areas is described. The principal feature of the method is a data smoothing technique employing Fourier transforms. The smoothing eliminates most of the random fluctuations without effecting the spectral resolution and makes identification of maxima using a zero slope criterion possible. Using the same Fourier transform with different constants it is possible with a second transformation to improve the spectral resolution. The computer program has been written in FORTRAN IV for the MIT IBM 360 model 65 computer and also for the Toshiba Electric Co. GE 635 computer. The complete analysis of a 4096 channel spectrum containing several hundred peaks requires about 75 sec of computation time.

The Public Perception of Risk

There has been a very rapid increase in the use of probabilistic risk analysis (PRA) in recent years. Typically these studies calculate risk as the product of probability (or more correctly frequency) and consequences. This format of course does not account for any differences in the characteristics of the risk so that direct comparison of the results of such studies for different risks can be misleading. An example would be comparison of auto fatalities with commercial airline fatalities. In the United States there are annually about 50,000 auto fatalities and about 200 commercial airline fatalities. Yet it is clear that in our society there are many more people apprehensive about commercial air travel than driving in automobiles. There may be many reasons for this, among them being a risk aversion for large-consequence events. There are of course other characteristics that lead people to feel differently about risks for which the products of frequency and consequence are the same.

METHODS OF HAZARD ANALYSIS AND NUCLEAR SAFETY ENGINEERING

The accident at Three Mile Island has focused considerable attention on the methods of reliability analysis that can provide estimates of the risks associated with hazardous activities. It has become fairly common practice to use the term “hazard” to refer to the potential for producing some undesired consequence, while the term “risk” is used to refer to some function of the undesired consequence and its probability of occurrence. The most commonly used function is the simple product of probability and consequence magnitude. Reliability methods are those techniques for identifying system failure modes and estimating their probability of occurrence. The purpose of this paper is to review how these methods have been applied to nuclear power plants and, when combined with calculations of consequences, have been used to make risk estimates of nuclear power plants. Because of the author’s close association with the Reactor Safety Study (WASH 14001, the discussion will focus mainly on the approach used in that study.’ The paper will also examine the strengths and shortcomings of the study in predicting an accident like Three Mile Island.

GAMANL : a computer program applying Fourier transforms to the analysis of gamma spectral data

GAMANL, a computer code for automatically identifying the peaks in a complex spectra and determining their centers and areas, is described. The principal feature of the method is a data smoothing technique employing Fourier transforms. The smoothing eliminates most of the random fluctuations without effecting the spectral resolution and makes identification of maxima using a zero slope criterion possible. Using the same Fourier transform with different constants it is possible with a second transformation to improve the spectral resolution. The computer program has been written in FORTRAN IV for the M.IT. IBM 360 model 65 computer and also for the Toshiba Electric Company G.E. 635 computer. The complete analysis of a 4096 channel spectrum containing one hundred twenty peaks requires about 75 seconds of comput-

Six‐Meter Radius Bent‐Crystal Spectrograph for Nuclear Gamma Rays

A six‐meter radius bent‐crystal spectrograph for the precision measurement of nuclear gamma‐ray wavelengths has been designed, constructed, and placed into operation at the Massachusetts Institute of Technology. This instrument is particularly well suited for directly measuring neutron capture gamma rays produced by samples placed in the through port of the MIT research reactor. The spectrograph is designed to measure wavelengths of gamma rays in the energy region from 0.1 to 4.0 Mev with an estimated precision that varies from about 0.01% at 0.1 Mev to 0.3% at 4 Mev. Photographic methods are used to record the gamma‐ray lines on the focal circle. A bent crystal is used to diffract and focus the gamma rays. Line width and efficiency data have been obtained for the (310), (003), and (006) planes of quartz. The efficiency of the instrument is quite low. In order to record a line at 2.0 Mev an exposure time of about 6000 curie hours is required.

Gamma rays following the decay of Nd147 and Sm153

Abstract A two meter radius bent quartz crystal spectrograph has been used to study gamma rays following the β-decay of Nd147 and Sm153. A gamma ray of 91.05±0.04 keV was observed following the decay of Nd147. This gamma ray corresponds to the transition between the first excited level and the ground state of the isotope Pm147. Three gamma rays are observed in the decay of Sm153. Two strong lines at 103.17±0.04 keV and 69.66±0.02 keV correspond to short-lived isomeric levels in Eu153. These have been observed previously. In addition, a weak line at 97.42±0.04 keV is present. A line at approximately this energy has been observed in the electron capture decay of Gd153 to Eu153. The intensity ratio of the 103.17 keV transition to the 97.42 keV line is greater than 20 to 1.

A probabilistic risk assessment-related methodology to support performance-based regulation within the nuclear power industry

Maintenance and inspection costs at nuclear power plants consume a large portion of a utility`s resources. The stresses of commercial competition make better resource allocation for such procedures vital. A nuclear power plant`s probabilistic risk assessment (PRA) is an excellent source of information about the safety importance of various plant systems, structures, and components. As both the nuclear power industry and the US Nuclear Regulatory Commission begin to focus attention on the use of performance-based regulation, it is important to find how best to put a nuclear power plant`s PRA to work in prioritizing maintenance and inspection resources. In light of these concerns, two ratios were developed to compare the risk significance of individual components to the amount of plant staff time, or burden, associated with inspecting the component. These risk-to-burden ratios point out existing disparities between inspection practices and safety concerns. These ratios can be used to develop new inspection schedules constituting a more equitable risk-to-burden distribution.

Nuclear power: Rasmussen on reactor safety: How nuclear power reactor risks are quantified; and nuclear sabotage, theft, shipping, and waste disposal risks put in perspective

Describes how nuclear power reactor risks are quantified; and nuclear sabotage, theft, shipping, and waste disposal risks put in perspective.

REACTOR PHYSICS PROJECT PROGRESS REPORT NO. 2.

Statement of responsibility on title page reads: Editors: M.J. Driscoll, I. Kaplan, D.D. Lanning; Contributors: V. Agarwala, F.M. Clikeman, J.N. Donohew, M.J. Driscoll, G. T. Hamilton, T.L. Harper, Y. Hukai, I. Kaplan, T. J. Kelley, D.D. Lanning, T.C. Leung, E.L. McFarland, N.C. Rasmussen, S.S. Seth, J.M. Sicilian, G.E. Sullivan, A.T.Supple and T.J. Thompson

REACTOR PHYSICS PROJECT PROGRESS REPORT.

Statement of responsibility on title page reads: Editors: M.J. Driscoll and T.J. Thompson; Contributors: F.M. Clikeman, J.N. Donohew, M.J. Driscoll, J.D. Eckard, T.L. Harper, Y. Hukai, I. Kaplan, C.H. Kim, Y.-M. Lefevre, T.C. Leung, N.R. Ortiz, N.C. Rasmussen, C.S. Rim, S.S. Seth, A.T. Supple C. Takahata, and T.J. Thompson