function u = ctrl_scram(t, x, plant, ref)
% CTRL_SCRAM  Emergency shutdown: max negative rod worth inserted.
%
%  Applies the full scram rod worth instantaneously.  In a real plant the
%  rods free-fall in ~2-3 seconds; this idealized version steps to the
%  final worth at t = t_scram.  Good enough for first-pass reachability,
%  conservative for safety arguments (faster insertion => less excursion).
%
%  u = -8 * beta   (~8 $, in the typical 8-10 $ regulatory band)
%
%  Same feedback-linearization comment as ctrl_shutdown: this dominates
%  any plausible feedback the reactor can produce en route from any
%  power/temperature state.
%
%  Inputs:
%    t, x, plant, ref - standard signature; all unused here.

    u = -8 * plant.beta;

end