Solution of the solar neutrino problem is significantly depends on the next generation of detectors that can measure the neutrino radiation from the Sun in intermediate energies. An intense (~ 1 MCi) 3 7 Ar source would be an ideal tool for the calibration of new solar neutrino detectors. The technology of the production of such a source is based on the irradiation of a large mass of a Ca-containing target in a high-flux fast-neutron reactor. Produced 3 7 Ar extracted from this target, will be purified and encapsulated in a source holder. A joint scientific collaboration of Russian, US and Japanese institutions are researching and developing the initial steps of this work and are funded by ISTC and CRDF.