The present document discusses the results of the measurements carried out during the test run performed before the main beam time of the HRMT-15 (RPINST) experiment in the HiRadMat facility, which is planned for October 2012. A prototype detector, specifically designed for measuring pulsed neutron fields, was employed in different positions in order to evaluate the stray neutron field conditions in the TA7 tunnel of HiRadMat. Critical points to be taken into account for the main experiment in October are presented, along with solutions to overcome them.