Castleford came through their last match before Sunday’s Tetley’s Challenge Cup semi-final against Widnes Vikings with no major injury concerns and Powell felt a testing opening period will stand his team in good stead.
London, who have yet to win this year, led twice in the first quarter, before Justin Carney’s eight-minute hat-trick set Castleford – whose previous Cup semi-final was in 2011 – on course for their highest score of the season.
“It was a tough game for a period,” Powell said.
“They rattled us a bit early on, we were a bit sloppy and they put some points on us, but I don’t think it matters.
“We are expecting a tough game on Sunday and it feels like it has been an age getting to a point when we can talk about the semi-final.
“We have got it in front of us, it is one game and we need to get it right. We need to be composed and calm and get our preparation right.
“We’ve had some tough games recently, so we’ve got plenty of experience.”
Carney faces an anxious wait to hear if he will be charged after being penalised for a dangerous tackle in the second half.
Powell said: “He lifted him up a little bit, but I don’t think there was anything dangerous.”
The coach confirmed Castleford will appeal against a two-match suspension which is set to keep former Leeds Rhinos forward Weller Hauraki out of the semi-final as well as the win over London.
The Broncos made a good start, but failed to cope when put under pressure and their regular errors gave Castleford, even playing well within themselves, the opportunity to run up a huge score.
Carney was the destroyer in chief, crossing after 25, 30 and 33 minutes to transform a 12-6 deficit into a 22-12 lead.
His first two scores were routine efforts, the Australian touching down from kicks by Liam Finn and Marc Sneyd respectively, but he showed raw power for his third, a tremendous solo run tight to the left-hand touchline.
London had gone ahead after nine minutes through a close-range try by Olsi Krasniqi and were in again on 19 when substitute Erjon Dollapi crossed with his first touch,
Josh Drinkwater adding both conversions.
In between, Luke Dorn – who joined Castleford last autumn from London – scored a spectacular long-range try following a quick 20 metre tap re-restart by Kirk Dixon, after the winger had collected a high kick behind his own line.
Jamie Ellis created a try for Scott Wheeldon on the final play of the first half and Michael Shenton and Garreth Carvell both added to the tally within 10 minutes of the resumption.
The second 40 was little more than a training run for Castleford, who increased their score at regular intervals.
London’s defence did a better job of keeping Carney in check, but that just created space on the other wing for Dixon to go over twice.
Frankie Mariano and Adam Milner also touched down and Sneyd finished with eight conversions, before Mike McMeeken scored a late consolation for London, improved by Drinkwater.
Castleford have already announced London winger Denny Solomona and loose-forward Matt Cook as recruits for next season and coach Joe Grima confirmed afterwards that hooker Scott Moore will be joining them.
He said: “It will be fantastic for them.
“Daryl is a very good coach and he is going to be very good for those three, as they will be for the club.”
Castleford Tigers: Dorn, Dixon, Gibson, Shenton, Carney, Sneyd, Finn, Jewitt, Milner, Huby,Holmes, Webster, Massey. Substitutes: Mariano, Wheeldon, Ellis, Carvell.
London Broncos: Farrar, Atkins, Minns, Mataitonga, Solomona, Keyes, Drinkwater, Slyney, Moore, Krasniqi, McMeeken, Vea, Cook. Substitutes: Wicks, Griffin, Wallace, Dollapi.
Referee: J Cobb (RFL).