The maximum energy is defined by the possibility of the beam injection into the main ring, the booster circumference is equal to 1/3 of the Nuclotron one. The repetition rate and acceptance are limited by characteristics of the superconducting magnets. New results of the Nuclotron booster conceptual design, a 250 MeV/Amu rapid cycling superconducting synchrotron at a 1 Hz repetition rate and a circumference of 84 m, are presented. The paper describes different options of heavy ion accumulation in the booster for upgrading Nuclotron beam intensities. They are a traditional multiturn and “skew” injection, accumulation of exchange, acceleration of ions with filled K and L shells protons, deuterons and heavy ions up to carbon by charge, their stripping at the booster exit and transfer into the main ring. Numerical estimations of the injection efficiency are given. The application of electron cooling at the superconducting accelerator is considered. The layout of the booster, Nuclotron, linac and beam transfer lines in the Synchrophasotron building is shown in Fig.1. The booster magnetic lattice is presented in detail in [1]. In this paper we consider two operation modes of the booster: heavy ion accumulation and cooling. The progress in the tests of the lattice superconducting magnet prototypes is presented as well. The set of Nuclotron heavy ion sources: a duoplasmatron (for protons, deuterons and α-particle), a source of polarized deuterons, a laser source (for nuclei up to silicon and an electron beam ion source (EBIS, for the heaviest ions) allows one to get ion beams over a wide range of masses. The existing injector (the Alvarez type linac), accelerates ions up to 5 MeV/u and protons up to 20 MeV/u at 1 Hz repetition rate, with a charge-to-mass ratio 0.33 ≤ q/A ≤ 0.5 and 0.28 ≤ q/A ≤ 0.5 after a coming upgrade. The problem of heavy ion beam high intensity can be solved by means of including the rapid cycling superconducting booster [1] in the accelerator facility scheme. The general parameters of this accelerator are presented in the Table 1.