Neutron shielding and activation of the MASTU device and surrounds

TL;DR

This paper assesses neutron shielding and activation issues for the upgraded MASTU device, identifying insufficiencies in current measures and proposing improvements to ensure safety during increased neutron radiation emissions.

Contribution

It provides a detailed analysis of neutron shielding and activation challenges for MASTU's upgrade, offering specific recommendations for enhanced safety measures.

Findings

Existing shielding is insufficient in some areas

Recommendations include improved shielding doors and tunnel modifications

Addresses neutronic dose rate questions like skyshine

Abstract

A significant functional upgrade is planned for the Mega Ampere Spherical Tokamak (MAST) device, located at Culham in the UK, including the implementation of a notably greater neutral beam injection power. This upgrade will cause the emission of a substantially increased intensity of neutron radiation for a substantially increased amount of time upon operation of the device. Existing shielding and activation precautions are shown to prove insufficient in some regards, and recommendations for improvements are made, including the following areas: shielding doors to MAST shielded facility enclosure (known as "the blockhouse"); north access tunnel; blockhouse roof; west cabling duct. In addition, some specific neutronic dose rate questions are addressed and answered; those discussed here relate to shielding penetrations and dose rate reflected from the air above the device ("skyshine").