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The human factor in licensing and operating the next generation of nuclear plants
As human factors specialists working at the intersection of human performance and nuclear operations, we are witnessing one of the nuclear sector’s most significant transitions in decades. The emergence of small modular reactors, microreactors, and other advanced designs is reshaping the industry’s landscape. Digital instrumentation and controls, passive safety systems, and increased automation are creating opportunities for greater safety margins and more flexible operation. These same features also fundamentally redefine what it means to “operate” a nuclear plant. Interactions among human roles, automation, and passive systems shape how people maintain awareness, exercise judgment, and intervene when necessary. These developments affect both operational realities and the regulatory foundations on which nuclear safety is built.
Sourena Golesorkhi, Blair P. Bromley, Matthew H. Kaye
Nuclear Technology | Volume 194 | Number 2 | May 2016 | Pages 178-191
Technical Paper | doi.org/10.13182/NT15-30
Articles are hosted by Taylor and Francis Online.
The pressure-tube heavy water reactor (PT-HWR) has excellent potential as an operational technology to exploit the use of thorium. Reactor core configurations of an existing PT-HWR design with thorium-based fuels were simulated using the DRAGON/DONJON reactor physics code suite. The ultimate goal of this work was to achieve a self-sufficient equilibrium thorium cycle with a fissile inventory ratio (FIR) greater than unity (FIR ≥ 1.0) by altering the fueling configuration and leaving the reactor model relatively unchanged from the existing 700-MW(electric)–class PT-HWR design. A further constraint was the license requirements limiting the maximum channel and bundle powers of existing PT-HWRs. To improve the breeding potential in the PT-HWR, heterogeneous seed and blanket core configurations were selected for assessment as opposed to using a homogenous core configuration with one single type of fuel. A number of bundle design concepts were modeled with DRAGON: A 24-element variant of the internally cooled annular fuel bundle was chosen for the seed fuel, and a conventional 28-element bundle was used for the blanket fuel. Two annular heterogeneous core configurations were considered: inner seed outer blanket (ISOB) and inner blanket outer seed (IBOS). Time-average and instantaneous power calculations were performed using DONJON. It was found that while the ISOB configuration could attain net breeding (FIR ≥ 1.0), the maximum channel and bundle powers exceeded the defined limits. When the reactor was derated to reduce these powers, the fuel cycle fell just below net breeding, although it did have a very high FIR. The IBOS configuration could meet the power limits without derating but was not self-sufficient. Despite not being net breeders, the FIR in both cases was very close to unity (0.986 to 0.995). Work is continuing to further optimize the fuel bundle concepts and core configurations and to achieve net breeding. Overall, the PT-HWR shows great promise for the current-generation implementation of the thorium fuel cycle.
