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RSCS MCNP Expertise Benefits Reactors and Accelerators
Posted on August 27th, 2013

In the current domestic energy market, nuclear power plants are compelled to increase their output and efficiency to compete with the oil and gas sectors.  One approach is to perform power uprates by increasing the turbine flow rates on BWR units.  Public and worker dose implications require consideration during an uprate as N-16 activity increases with the flow rate.  RSCS is currently modeling the dose implications from increasing BWR turbine flow rates, using Monte Carlo N-Particle (MCNP) calculations to determine the increased dose rates from N-16 and subsequent shielding required to maintain regulatory compliance. MCNP is an established technique that simulates the passage and interactions of individual particles through matter using the Monte-Carlo algorithm.  MCNP is well suited for complex source and shield geometries where deterministic and point kernel methods are too cumbersome to perform or would be less accurate.    

Engagement to perform MCNP modeling for BWR plants resulted from RSCS’s experience with performing MCNP analyses for new-build cyclotrons and accelerators that have come on-line to meet the increasing need for therapeutic and industrial radionuclides.  RSCS has worked with several nuclide production facilities (both domestic and international) to simulate the shielding design of particle accelerator facilities and the subsequent activation nuclides for both operating and decommissioning purposes.  Dose rates are determined from the simulated radiation fluence rates and are subsequently coupled with conservative use and occupancy factors in order to determine compliance with the facility’s administrative and regulatory limits.  RSCS staff works directly with contracting architects to create precise 3D replications of the facility geometry in formats that are suitable for the conversion to MCNP type inputs.  Monte-Carlo techniques are then performed to determine the most limiting target bombardment scenario and subsequently transport the resultant radiations of consideration throughout the facility and to nearby areas occupied by both site employees and members of the public.  If the shielding proposed by the existing facility design is inadequate, RSCS works with the architects to revise the shielding design to meet regulatory limits and streamline the permitting and licensing approval processes.  

The MCNP work offered by RSCS is unique as there are only a handful of MCNP consultants that offer both Health Physics expertise coupled with understanding Monte Carlo techniques. RSCS is experienced in MCNP modeling problems such as particle accelerator facilities, photon irradiators, criticality detectors, neutron sources, and GM detectors.  Additional Monte Carlo analyses, such as material activation, can be performed on both primary and secondary sources of radiation resulting from the transport, storage, and processing of isotopes, as well as potential accident scenarios.  RSCS excels at performing these analyses, solving complex regulatory problems for our nuclear power and accelerator clients.

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