The Electric Power Research Institute (EPRI) has issued report 1003483, “Comparative Analysis of Nebula and MOV Long Life Greases for Limitorque Main Gearbox Applications”. This report is dated December, 2002.
This report addressed the need for a replacement for the obsolete and discontinued Nebula EP grease. It is stated that the work was undertaken to qualify MOV Long Life by comparison with Nebula in thermal and radiation exposures simulating service, main steam line break (MSLB) and loss of coolant accident (LOCA) conditions. Testing was done under Herguth Laboratories 10 CFR50, Appendix B, Quality Assurance Program. This included;
- oven aging at 150°C for 300 hours,
- gamma irradiation to 220 Mrad, and
- thin film air and thin film steam exposure at 150°C.
Analytical tests were penetration, weight loss, dropping points, infrared (FTIR) traces, differential scanning calorimitry (DSC), rheometer studies, and pin on disc (POD).
MOV Long Life was said to be superior to Nebula in essentially all key performance respects. Further, that because MOV Long Life is compatible with Nebula that no problems are expected when adding it to actuators in service. Mixtures also tended to perform as well as or better than pure Nebula. As a result MOV Long Life is considered an acceptable replacement for Nebula in both mild and harsh environment