Shielding technology for upper structure of HTTR

Ueta, Shohei; Sakaba, Nariaki; Sawa, Kôichiro

doi:10.1016/j.anucene.2016.02.021

Cited by 5 publications

(1 citation statement)

References 10 publications

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“…In the PWR (pressurized water reactor), water itself provides good shielding for the main vessel. In the HTGR (high temperature gas-cooled reactor), the permanent reflector block is used to moderate the fast neutron and the side shielding blocks composed of B 4 C/C, and SUS 316 stainless steel casing is employed as in-reactor shielding [16]. In the MSFR, curved blanket walls are used to reduce the irradiation damages of the outer main vessel [17].…”

Section: Introductionmentioning

confidence: 99%

Neutron/Gamma Radial Shielding Design of Main Vessel in a Small Modular Molten Salt Reactor

Zhu

Zou

et al. 2023

JNE

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The SM-MSR (small modular molten salt reactor) has a good prospect for development with regards to combining the superiority of the molten salt reactor and modularization technologies, showing the advantages of safety, reliability, low economic cost and flexibility of site selection. However, because its internal structural parts are not easily replaced, and the outer shielding structure is limited, the lifespan of the reactor vessel and its in-reactor shielding design needs to be addressed. In order to find an optimal shielding model with both high fuel efficiency and strong radiation shielding capability, five different design schemes were proposed in this work, which varied in thickness and boron concentration in inner-shielding materials. The neutron/gamma flux and DPA (displacements per atom)/helium production rates were evaluated to obtain an appropriate scheme. Several beneficial results were obtained. Considering the above factors and the actual manufacturing process, 20 cm-thick boron graphite with a 5 wt% Boron-10 concentration combined with a 1 cm-thick Hastelloy barrel was chosen as the in-reactor shielding structure. Outside the reactor, the neutron flux was reduced to 8.33 × 1010 cm−2 s−1, and the gamma flux was decreased to 1.13 × 1011 cm−2 s−1. The vessel/barrel material could maintain a lifespan of more than 10 years, while the burnup depth was 6.25% lower than that of a model without inner-shielding. The conclusions of this research can provide important references for the shielding design and parameter selections of small molten salt reactors in the future.

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Section: Introductionmentioning

confidence: 99%

Neutron/Gamma Radial Shielding Design of Main Vessel in a Small Modular Molten Salt Reactor

Zhu

Zou

et al. 2023

JNE

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Calculation of shutdown gamma distribution in the high temperature engineering test reactor

Ishii

Nagasumi

et al. 2022

Nuclear Engineering and Design

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Shutdown dose rate calculations in high-temperature gas-cooled reactors using the MCNP-ORIGEN activation automation tool

Fairhurst-Agosta,

Kozlowski

2023

nuclscitechnolopenres

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Background High-temperature gas-cooled reactors (HTGRs) have many distinct features from the current light water reactor (LWR) fleet, and potential decommissioning strategies should take them into consideration. The proper characterization of the shutdown dose rates can establish a suitable strategy. Methods This article introduces a new shutdown dose rate calculation capability that relies on the MCNP-ORIGEN activation automation tool and the MCNP repeated structures to explicitly model the TRistructural ISOtropic (TRISO) particles as decay radiation sources. Results Three exercises are conducted with this capability, and their results discussed. The first two exercises verify and demonstrate the workflow. The third exercise proposes a decommissioning strategy for a high-temperature gas-cooled microreactor and studies its feasibility from the shutdown dose rate standpoint. The calculations yield a dose rate map above at the reactor citadel after a three month cool-down, showing values above 40 mSv/h. Conclusions The findings imply that the decommissioning strategy based on placing the reactor in a safe shutdown state and allowing it to cool down for three months before removing various components and extracting the fuel assemblies, may not be sufficient to minimize unnecessary exposure of personnel.

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Shielding technology for upper structure of HTTR

Cited by 5 publications

References 10 publications

Neutron/Gamma Radial Shielding Design of Main Vessel in a Small Modular Molten Salt Reactor

Neutron/Gamma Radial Shielding Design of Main Vessel in a Small Modular Molten Salt Reactor

Calculation of shutdown gamma distribution in the high temperature engineering test reactor

Shutdown dose rate calculations in high-temperature gas-cooled reactors using the MCNP-ORIGEN activation automation tool

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