A freezing valve resulted in a water spill on the grounds of Entergy's River Bend nuclear plant Tuesday, but it did not pose a risk to public health.A report filed with the Nuclear Regulatory Commission and released Thursday indicated between 100 and 1,200 gallons leaked because of the valve connected to a cooling tower blow-down line. Upon discovering the leak, crews erected barriers to keep the water from reaching storm drains and confined the spill to plant grounds. At the time the event was reported, the leak had been reduced to a small drip and repairs were underway. The report said the water contained 4,584 pico-curies per liter of tritium, with no detectable gamma activity. By comparison, the EPA limit on tritium in drinking water is 20,000 picocuries per liter. The low temperature in St. Francisville, La., where the plant is located dropped to 19 F on Tuesday when the valve broke.