The popular Canberra Raiders forward needs a medical clearance to be allowed to firstly return to contact training and then to return to play.

He's been sidelined since he suffered a terrifying seizure during the Raiders-South Sydney game at Homebush in May last year - more than 10 months ago - when he was taken to hospital in an ambulance after collapsing on the field during play.

Harawira-Naera has had a defibrillator inserted in his chest, near his armpit, to help with his underlying heart condition.

While there have been cases of professional soccer players continuing their careers with a defibrillator, no one has been cleared to play a brutal collision sport like rugby league at the elite level.

The 28-year-old has been cleared to increase his training intensity, but gaining that medical clearance for contact has proved problematic - which was why his management were seeking a second opinion.

The news comes as the Raiders look to return to the winners' circle when they take on Cronulla at Shark Park on Easter Sunday.

While they've lost captain Elliott Whitehead to a recurring calf injury, they've been bolstered by the returns of Sebastian Kris (concussion) and Corey Horsburgh.

Raiders coach Ricky Stuart said Horsburgh will play at prop when he comes off the bench for his first NRL game of the season.

Initially, Stuart was going to bring Horsburgh back into the NRL side for next week's home game against Parramatta, but that's been brought forward due to Whitehead's calf.

Stuart said there were no dramas bringing Horsburgh back through NSW Cup - especially after they won their opening two games of the season.

"We've all got team-first mentality here. It's easy to say, sometimes it's hard to live," he said.

"But when the environment is strong and the culture is strong, players, staff have that and that's what it's all about.

"And it's very hard to change a winning formula after the first two games."

The Raiders have also lost outside back Albert Hopoate to a barbecue accident that led to second-degree burns on his right arm.

Despite having an arm covered in blisters, Stuart revealed Hopoate still fronted for training on Monday ready to go.

But Canberra medical staff were concerned about the potential of infection if he trained and played.

"Poor Albert - he never likes to give up his position at all," Stuart said.

"He turned up here on Monday ready to train. It was the day after he'd had the explosion with the barbecue, he was here the next day strapped up.

"There was no way we were going to risk him. He had second-degree burns to his arm."

NRL ROUND 4

Sunday: Canberra Raiders v Cronulla Sharks at Shark Park, 6.15pm.

Raiders squad: 1. Jordan Rapana, 2. James Schiller, 3. Matt Timoko, 4. Sebastian Kris, 5. Xavier Savage, 6. Ethan Strange, 7. Jamal Fogarty, 8. Josh Papali'i, 9. Danny Levi, 10. Joe Tapine, 11. Hudson Young, 16. Zac Hosking, 13. Morgan Smithies. Interchange: 14. Tom Starling, 15. Ata Mariota, 17. Pasami Saulo, 19. Corey Horsburgh. Reserves: 20. Kaeo Weekes, 22. Nick Cotric.

Sharks squad: 1. Will Kennedy, 2. Sione Katoa, 3. Jesse Ramien, 4. Kayal Iro, 5. Ronaldo Mulitalo, 6. Braydon Trindall, 7. Nicho Hynes, 8. Tom Hazelton, 9. Blayke Brailey, 10. Oregon Kaufusi, 11. Siosifa Talakai, 12. Teig Wilton, 13. Cam McInnes (c). Interchange: 14. Daniel Atkinson, 15. Jack Williams, 16. Billy Burns, 17. Tuku Hau Tapuha. Reserves: 18. Jayden Berrell, 19. Blake Hosking.