Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Mitigation”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,657 records · Page 92
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Insider Threat - Material Control and Accountability Mitigation (Presentation)

Why is the insider a concern? There are many documented cases of nuclear material available for sale - there are more insider diversions than outsider attacks and more than 18 documented cases of theft or loss of plutonium or highly enriched uranium. Insider attributes are: have access, has authority, possesses knowledge, works with absence of timeline, can test system, and may act alone or support a team. Material control and accountability (MC&A) is an essential part of an integrated safeguards system. Objectives of MC&A are: (1) Ongoing confirmation of the presence of special nuclear material (SNM) in assigned locations; (2) Prompt investigation of anomalies that may indicate a loss of SNM; (3) Timely and localized detection of loss, diversion, or theft of a goal quantity; (4) Rapid assessment and response to detection alarms; and (5) Timely generation of information to aid in the recovery of SNM in the event of an actual loss, diversion, or theft from the purview of the MC&A system. Control and accountability of material, equipment, and data are essential to minimizing insider threats.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2020

Proposed Potential Mitigation of Wastewater Disposal Through Treated Produced Water in Bakken Formation

The recent global expansion in the development of unconventional oil and gas assets has also resulted in a tremendous increase in the number of extended horizontal drilling and hydraulic fracturing projects in the Bakken. The United States is presently the largest global crude oil producer, and the Bakken Formation in North Dakota is one of the major contributors to this achievement. However, the wastewater produced from these increased oilfield activities are highly saline (∼170,000 to 350,000 ppm TDS) and no technology currently available can satisfactorily treat it. As a result, more than 90% of wastewater in the Bakken is disposed of by deep injection into disposal wells. However, there are growing environmental and operational concerns about the sustainability and impacts of this approach. Research has shown that cumulative wastewater injection in some areas could increase the chances of earthquakes in those areas. However, if this produced water is efficiently treated, it could be reused in hydraulic fracturing operations or to support coal mining and irrigation activities. All these applications would reduce the need for wastewater injection and reduce the demand for fresh water used in hydraulic fracturing operations across North Dakota. For this purpose, we propose an enhanced supercritical technology we call Supercritical Water Extraction – Enhance Targeted Recovery to handle the issue of high TDS of flowback and produced water in the Bakken.

04 OIL SHALES AND TAR SANDS↗
DOE OSTI2012

The AP1000{sup R} nuclear power plant innovative features for extended station blackout mitigation

Station Blackout (SBO) is defined as 'a condition wherein a nuclear power plant sustains a loss of all offsite electric power system concurrent with turbine trip and unavailability of all onsite emergency alternating current (AC) power system. Station blackout does not include the loss of available AC power to buses fed by station batteries through inverters or by alternate AC sources as defined in this section, nor does it assume a concurrent single failure or design basis accident...' in accordance with Reference 1. In this paper, the innovative features of the AP1000 plant design are described with their operation in the scenario of an extended station blackout event. General operation of the passive safety systems are described as well as the unique features which allow the AP1000 plant to cope for at least 7 days during station blackout. Points of emphasis will include: - Passive safety system operation during SBO - 'Fail-safe' nature of key passive safety system valves; automatically places the valve in a conservatively safe alignment even in case of multiple failures in all power supply systems, including normal AC and battery backup - Passive Spent Fuel Pool cooling and makeup water supply during SBO - Robustness of AP1000 plant due to the location of key systems, structures and components required for Safe Shutdown - Diverse means of supplying makeup water to the Passive Containment Cooling System (PCS) and the Spent Fuel Pool (SFP) through use of an engineered, safety-related piping interface and portable equipment, as well as with permanently installed onsite ancillary equipment. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2012

Chemistry control and corrosion mitigation of heat transfer salts for the fluoride salt reactor (FHR)

The Molten Salt Reactor Experiment (MSRE) was a prototype nuclear reactor which operated from 1965 to 1969 at Oak Ridge National Laboratory. The MSRE used liquid fluoride salts as a heat transfer fluid and solvent for fluoride based {sup 235}U and {sup 233}U fuel. Extensive research was performed in order to optimize the removal of oxide and metal impurities from the reactor's heat transfer salt, 2LiF-BeF{sub 2} (FLiBe). This was done by sparging a mixture of anhydrous hydrofluoric acid and hydrogen gas through the FLiBe at elevated temperatures. The hydrofluoric acid reacted with oxides and hydroxides, fluorinating them while simultaneously releasing water vapor. Metal impurities such as iron and chromium were reduced by hydrogen gas and filtered out of the salt. By removing these impurities, the corrosion of reactor components was minimized. The Univ. of Wisconsin - Madison is currently researching a new chemical purification process for fluoride salts that make use of a less dangerous cleaning gas, nitrogen trifluoride. Nitrogen trifluoride has been predicted as a superior fluorinating agent for fluoride salts. These purified salts will subsequently be used for static and loop corrosion tests on a variety of reactor materials to ensure materials compatibility for the new FHR designs. Demonstration of chemistry control methodologies along with potential reduction in corrosion is essential for the use of a fluoride salts in a next generator nuclear reactor system. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2016

SiC cladding corrosion and mitigation

Silicon carbide (SiC) is a leading candidate for accident tolerant fuel. Testing of SiC in autoclaves at 360 C. degrees in simulated coolant resulted in little corrosion. However, testing of SiC tubes in the Massachusetts Institute of Technology (MIT) reactor manufactured in the same way had unacceptable corrosion levels. This in-reactor SiC corrosion issue is now being addressed by Westinghouse in tests being carried out at our Churchill, PA facility and in tests in the MIT reactor. The suspected driver for the excessive corrosion is the generation of oxidative water radiolysis products in the core. The MIT reactor was identified as running at H{sub 2} levels of ∼20 to 22 cc/kg coolant (cubic centimeters standard temperature and pressure per kilogram coolant) which were below those normally specified in operating pressurized water reactors (PWRs) of 25 to 50 cc/kg. Hydrogen is used to react with the radiolysis products to reduce them to water. The current MIT reactor tests will be run at H{sub 2} concentration levels of ∼50 cc/kg. The applicability of this approach has been supported by recent papers in the literature. Parallel testing at Churchill is being carried out to verify the efficacy of this approach using autoclaves operating at 345 C.degrees with H{sub 2}O{sub 2} injection to simulate the water radiolysis products. Various concentrations of H{sub 2} are being tested to determine the effect on SiC corrosion rate. Further studies are underway to investigate the effects of different SiC fabrication and structural parameters and to optimize for improved corrosion performance. This paper compares the results of the corrosion tests in the MIT reactor and the autoclave tests with H{sub 2}O{sub 2} injection and the effect of H{sub 2} injection on the SiC corrosion rate. The results of the autoclave tests with H{sub 2}O{sub 2} addition indicate that corrosion rates for SiC can be achieved that are much higher than those achieved in a reactor. It appears that the use of H{sub 2}O{sub 2} addition in flow through loops to simulate the corrosion rate of SiC samples in reactor is feasible. The use of H{sub 2} addition to reduce the corrosion rate in-reactor of SiC appears to be feasible.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗