It has been proposed that, following a pressurized water reactor (PWR) loss-of-coolant accident (LOCA), sprays be used for the twofold purpose of pressure suppression and fission product (largely 131I) removal. These proposed sprays must operate under severe conditions of high energy radiation (∼3 × 108 rads) and temperature (∼135°C). Studies have been carried out on a series of such sprays to ascertain their stability under these conditions. It was found that several of the solutions exhibit satisfactory behavior under accident conditions while others were discarded from consideration because of either thermal and/or radiation instability. The two sprays found to demonstrate acceptable stabilities under test conditions are the basic borate (0.15N NaOH-3000 ppm B) and basic borate thiosulfate (1 wt% Na2S2 O3-0.15N NaOH-3000 ppm B). However, even these demonstrate a radiolytic gas generation (H2) sufficient to be a possible safety hazard. Various studies have been carried out to establish G(H2) values and/or equilibrium radiolytic gas concentrations. Other studies were carried out on possible spray solution interaction with reactor containment metals and alloys.