Engineering Papers⌕ Search

Engineering topics

Pena, Michael

Publications and source records attributed to Pena, Michael.

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Yield and PDV Measurements of the Godiva-IV Critical Assembly (Preliminary Report)

A high dynamic range, scinillator based detector, the MHD-240, was used to measure the gamma and neutron flux of several prompt critical bursts of the Godiva-IV assembly. The measurements provided the alpha and FWHM for several different burst temperatures. Calibrations of the MHD240 gamma and neutron sensitivity along with MCNP based simulation of the Godiva-IV assembly will allow us to also determine the total fission yield of the burst integrated over approximately 5 ms. Work is ongoing to check the calibrations of the MHD-240, and improve the MCNP simulations. This is a preliminary report, and the fission yields reported here are not final and are likely inaccurate. The measured alpha and FWHM are not impacted by the calibration issues and are considered final.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Yield and PDV Measurements of the Godiva-IV Critical Assembly

A high dynamic range, scinillator based detector, the MHD-240, was used to measure the gamma and neutron flux of several prompt critical bursts of the Godiva-IV assembly. The measurements provided the alpha and FWHM for several different burst temperatures. Calibrations of the MHD240 gamma and neutron sensitivity along with MCNP based simulation of the Godiva-IV assembly allowed us to also determine the total fission yield of the burst integrated over approximately 5 ms. In addition a Photo Doppler Velocimetry measurement was conducted to determine the surface motion vibrational frequency of Godiva-IV assembly during the bursts. The combined data were collected to be used as input to multi-physics simulation of the Godiva-IV assembly. This is a preliminary report, there is an ongoing effort to update the MCNP simulations used in the analysis and develop a correction for the room return component of the measured signal.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2017

Modeling of Hypervelocity Impact Experiments Using Gamma-SPH Technique

Hypervelocity impact research has been conducted using light gas guns to characterize materials under shock conditions. Hypervelocity impact produces high pressure and temperature states during the projectile-target interaction. Projectile and target materials both experience severe localized deformation under these conditions, which creates stretching, bending, and complete perforation in thin target plates. Relatively thick target plates show several failure modes, such as spalling, petalling, discing, and plugging. These failure modes are mostly controlled by several factors such as impact velocity, material properties, loading geometry, etc. Gas gun experiments were performed to measure the plastic deformation of steel plates during hypervelocity impact. The MPDV system was used to measure free surface velocity during these experiments. Simulation models developed in the IMPETUS AFEA Gamma SPH solver show that the physical measurements of impact cratering and bulge are in reasonable agreement with simulation results. Velocity profiles are in general agreement with the experiments capturing all the major features observed experimentally.

36 MATERIALS SCIENCE↗
DOE OSTI2017

An Overview of Broadband Laser Ranging (BLR) Architecture and Measurement Considerations

Broadband Laser Ranging (BLR) is a developmental diagnostic intended to measure the position of rapidly moving surfaces in combination with optical velocimetry. Design and employment of a BLR diagnostic on dynamic experiments requires consideration for both the inherent measurement system tradeoffs as well as architectural choices appropriate to the nature of investigation. The diagnostic uses spectral interferometry to measure distance by mapping femtosecond laser pulses to the time domain via chromatic dispersion within the fiber-optic architecture. The system parameters and governing equations that describe measurement range, resolution, and Doppler sensitivity will be discussed. We will also briefly review the impact of diagnostic architectural choices including: nature of interferometer, Interferometric dispersion matching, optical amplification, integration of optical velocimetry, BLR calibration, and field operability. To summarize we will present the architectural and operational approach currently being pursued by NSTec within an on-going collaboration between NSTec, Lawrence Livermore and Los Alamos National Labs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗