CONSTRUCTION STATUS AND ISSUES OF THE

This paper presents an overview of the construction sta-tus and technical issues of the Spallation Neutron Source (SNS) accumulator ring and the transports. DESIGN HISTORY The SNS project is presently in the 6th year of a 7-year construction cycle [2]. The SNS ring, designed and con-structed mainly by the Brookhaven National Laboratory, will accumulate pulses of 1.5×1014 protons of 1 GeV ki-netic energy at a repetition rate of 60 Hz [1]. With a beam power of 1.5 MW in the ring, the primary concern is beam-loss induced radio-activation that can limit the ring’s avail-ability and maintainability. With a dedicated beam colli-mation in the ring at an efficiency above 90%, the tolerable fractional beam loss is about 10−3 [3]. Several key decisions were made during the period of initial R&D and the first year of construction: A study was performed comparing the present structure of full-energy linac plus accumulator ring (AR) to a rapid-cycling-synchrotron (RCS) and validated the AR design for techni-cal feasibility and budgetary advantages [4]; A four-fold symmetric lattice was chosen to dedicate each straight sec-tion to injection, collimation, RF system, and extraction, isolating the highly radio-active collimation section from the rest for special maintenance handling; The injection was located at a dispersion-free region that allows inde-pendently adjustable painting in the transverse (with or-bit bumps in the ring) and longitudinal (with an energy-∗SNS is managed by UT-Battelle, LLC, under contract DE-AC05