Method of fission product beta spectra measurements for predicting reactor anti-neutrino emission
Not Available
Asner, D. M.↗
Engineering topics
Greenfield, Bryce A.
Publications and source records attributed to Greenfield, Bryce A..
Source Recertification, Refurbishment, and Transfer Logistics
The 2012 Gap Analysis of Department of Energy Radiological Sealed Sources, Standards, and Materials for Safeguards Technology Development report, and the subsequent Reconciliation of Source Needs and Surpluses across the U.S. Department of Energy National Laboratory Complex report, resulted in the identification of 33 requests for nuclear or radiological sealed sources for which there was potentially available, suitable material from within the U.S. Department of Energy (DOE) complex to fill the source need. Available, suitable material was defined by DOE laboratories as material slated for excess, or that required recertification or refurbishment before being used for safeguards technology development. This report begins by outlining the logistical considerations required for the shipment of nuclear and radiological materials between DOE laboratories. Then, because of the limited need for transfer of matching sources, the report also offers considerations for an alternative approach – the shipment of safeguards equipment between DOE laboratories or technology testing centers. Finally, this report addresses repackaging needs for the two source requests for which there was available, suitable material within the DOE complex.
Logistics↗
Predicting Reactor Antineutrino Emissions Using New Precision Beta Spectroscopy
Neutrino experiments at nuclear reactors are currently vital to the study of neutrino oscillations. The observed antineutrino rates at reactors are typically lower than model expectations. This observed deficit is called the “reactor neutrino anomaly”. A new understanding of neutrino physics may be required to explain this deficit, though model estimation uncertainties may also play a role in the apparent discrepancy. PNNL is currently investigating an experimental technique that promises reduced uncertainties for measured data to support these hypotheses and interpret reactor antineutrino measurements. The experimental approach is to 1) direct a proton accelerator beam on a metal target to produce a source of neutrons, 2) use spectral tailoring to modify the neutron spectrum to closely simulate the energy distribution of a power reactor neutron spectrum, 3) irradiate isotopic fission foils (235U, 238U, 239Pu, 241Pu) in this neutron spectrum so that fissions occur at energies representative of a reactor, 4) transport the beta particles released by the fission products in the foils to a beta spectrometer, 5) measure the beta energy spectrum, and 6) invert the measured beta energy spectrum to an antineutrino energy spectrum. A similar technique using a beta spectrometer and isotopic fission foils was pioneered in the 1980’s at the ILL thermal reactor. Those measurements have been the basis for interpreting all subsequent antineutrino measurements at reactors. A basic constraint in efforts to reduce uncertainties in predicting the antineutrino emission from reactor cores is any underlying limitation of the original measurements. This may include beta spectrum energy resolution, the absolute normalization of beta emission to number of fission, statistical counting uncertainties, lack of 238U data, the purely thermal nature of the IIL reactor neutrons used, etc. An accelerator-based neutron source that can be tailored to match various reactor neutron spectra provides an advantage for control in studying how changes in the neutron spectra (i.e. "in the reactor core") affects the resulting fission product beta spectrum. Furthermore, the 238U antineutrino spectrum, which has not been measured, can be studied directly because of the enhanced 1 MeV fast neutron flux available at the accelerator source. A facility such as the Project X Injector Experiment (PXIE) 30 MeV proton linear accelerator at Fermilab is being considered for this experiment. The hypothesis is that a new approach utilizing the flexibility of an accelerator neutron source with spectral tailoring coupled with a careful design of an isotopic fission target and beta spectrometer and the inversion of the beta spectrum to the neutrino spectrum will allow further reduction in the uncertainties associated with prediction of the reactor antineutrino spectrum.
Asner, David M.↗
Enhancing the Security of TIDs Using OSL
Tamper indicating devices (TIDs) such as tags and seals are integral to the safety and security of both equipment and nuclear material. They find prominence in both safeguards and arms control, yet many of the tags and seals in use today have been around for many years, with little or no serious modifications and security updates over their lifetime. There are many very simple changes or additions that can be implemented that will significantly enhance the security and robustness of both tags and seals. Incorporating optically stimulated luminescent (OSL) material is one example. OSL materials have found wide use in the nuclear community, currently in the form of millions of personnel dosimeters. However, the same properties that make it useful for dosimetry, can be utilized as a security feature in tags and seals to provide tamper indication, and potentially unique identification. When OSL materials are interrogated with specific wavelengths of light, they will excite and emit light at different, specific wavelengths. PNNL has undertaken to utilize this unique property of OSL material and incorporate the material into commercially available tags and seals. Currently PNNL is exploring two options; working with a manufacturer to incorporate OSL prior to distribution, or integration into commercially purchased TIDs just prior to use. PNNL is also developing a hand-held reader to interrogate and measure the light emitted from the OSL incorporated tags and seals. This paper discusses the evolution of this endeavor and the progress made to date. As part of this discussion, the success and future use of the idea of incorporating OSL material into tags and seals to enhance security and provide tamper indication will also be provided.
Miller, Steven D.↗