By Pedro Fonseca RIO DE JANEIRO, April 6 (Reuters) - Brazil's brutal surge in COVID-19 deaths will soon surpass the worst of a record January wave in the United States, climbing well beyond an average 3,000 fatalities per day, scientists predict, as contagious new variants overwhelm hospitals. Brazil's overall death toll trails only the U.S. outbreak, with nearly 333,000 killed, according to Health Ministry data, compared with more than 555,000 dead in the United States. But with Brazil's healthcare system at the breaking point, the country could also exceed total U.S. deaths, despite having two-thirds the population, two experts told Reuters. "It's a nuclear reactor that has set off a chain reaction and is out of control. It's a biological Fukushima," said Miguel Nicolelis, a Brazilian doctor and professor at Duke University, who is closely tracking the virus.