The Versatile Test Reactor (VTR) is currently under development by the U.S. Department of Energy (DOE). It will provide very high fast neutron flux irradiation capabilities that are currently unavailable in the U.S. Given the increasingly large number of advanced reactor concepts being pursued in recent years, this irradiation testing capability will be essential to support maturation of these concepts. Radiation protection is an important part of the VTR design. High neutron fluxes can pose a challenge for radiation protection of the structures and equipment near the reactor core. This paper provides a summary on the status of the shielding considerations and analysis performed for VTR. The paper focuses on the shielding needs for the secondary sodium flowing through the Intermediate Heat Exchanger (IHX), the air flowing through the Reactor Vessel Auxiliary Cooling System (RVACS), the dose rate above the reactor head access area, the radiation dose and flux in the neutron detectors, and the radiation damage on the reactor vessel wall and the structures near the core. One key challenge for the shielding design of VTR is the activation of the secondary sodium when it flows through the IHX. The IHXs are placed in the primary sodium pool inside the reactor vessel. During operation, neutrons produced in the core can reach the IHXs due to the small absorption cross section of sodium and the large mean free path of fast neutrons. The secondary sodium gets activated inside the IHX and emits photons in the secondary loop outside of the reactor vessel. Activation of secondary sodium needs to be mitigated in order to meet the radiation dose limit sets for personnel working at the plant as secondary sodium circulates outside of the reactor building to the air-dump heat exchangers. Similarly, for the RVACS, the air flowing in the system gets close to the reactor core, and some argon would become activated and released into the atmosphere. Thus, proper shielding is also required to reduce argon activation in the RVACS. The VTR design and development is underway and shielding considerations discussed in this paper will progress with the rest of the reactor.
The work reported in this summary is the result of studies supporting a VTR conceptual design, cost, and schedule estimate for DOE-NE to make a decision on procurement. As such, it is preliminary.
|Speaker's email email@example.com|
|Affiliation/Organization||Argonne National Laboratory|
|Country/Int. organization||United States of America|