diff --git a/src/control/control_rod.cpp b/src/control/control_rod.cpp
new file mode 100644
index 0000000..164d26a
--- /dev/null
+++ b/src/control/control_rod.cpp
@@ -0,0 +1,54 @@
+
+#include "control_rod.hpp"
+
+using namespace sim::control;
+
+control_rod::control_rod(double limit)
+{
+	this->limit = limit;
+}
+
+const char* control_rod::get_name() const
+{
+	return "Control Rod";
+}
+
+void control_rod::display(std::ostream& o) const
+{
+	o << "Inserted: " << (inserted * 100) << "%\n";
+	o << "Absorbed: " << absorbed << " / " << limit << "\n";
+};
+
+double control_rod::get_k(val_t type) const
+{
+	switch(type)
+	{
+	case val_t::HEAT:
+		return 1.0 / 16.0;
+	case val_t::N_SLOW:
+		return 1.0 / 4.0;
+	case val_t::N_FAST:
+		return 1.0 / 2.0;
+	}
+
+	return 0;
+}
+
+void control_rod::set_reactivity(double a)
+{
+	inserted = 1 - a;
+}
+
+void control_rod::update(double secs)
+{
+	update_rod();
+	
+	double m = (1 - absorbed / limit) * inserted;
+	double r_fast = vals[val_t::N_FAST] * m;
+	double r_slow = vals[val_t::N_SLOW] * m;
+
+	vals[val_t::N_FAST] -= r_fast;
+	vals[val_t::N_SLOW] -= r_slow;
+	absorbed += r_fast + r_slow;
+}
+
diff --git a/src/control/control_rod.hpp b/src/control/control_rod.hpp
new file mode 100644
index 0000000..202bb09
--- /dev/null
+++ b/src/control/control_rod.hpp
@@ -0,0 +1,28 @@
+
+#pragma once
+
+#include "../rod.hpp"
+
+namespace sim::control
+{
+
+class control_rod : public sim::rod
+{
+	double inserted = 1;
+	double absorbed = 0;
+	double limit;
+	
+	virtual const char* get_name() const;
+	virtual double get_k(sim::rod::val_t type) const;
+	virtual void display(std::ostream& o) const;
+
+public:
+
+	control_rod(double limit);
+
+	virtual void update(double secs);
+	void set_reactivity(double a);
+};
+
+}
+
diff --git a/src/coolant/pipe.cpp b/src/coolant/pipe.cpp
new file mode 100644
index 0000000..df8a646
--- /dev/null
+++ b/src/coolant/pipe.cpp
@@ -0,0 +1,34 @@
+
+#include "pipe.hpp"
+
+using namespace sim::coolant;
+
+const char* pipe::get_name() const
+{
+	return "Coolant Pipe";
+}
+
+double pipe::get_k(sim::rod::val_t type) const
+{
+	switch(type)
+	{
+	case val_t::HEAT:
+		return 1.0 / 16.0;
+	case val_t::N_SLOW:
+		return 1.0 / 4.0;
+	case val_t::N_FAST:
+		return 1.0 / 2.0;
+	}
+
+	return 0;
+}
+
+void pipe::update(double secs)
+{
+	update_rod();
+
+	double v = vals[val_t::N_FAST] * 0.25;
+	vals[val_t::N_FAST] -= v;
+	vals[val_t::N_SLOW] += v;
+}
+
diff --git a/src/coolant/pipe.hpp b/src/coolant/pipe.hpp
new file mode 100644
index 0000000..94ec5d4
--- /dev/null
+++ b/src/coolant/pipe.hpp
@@ -0,0 +1,20 @@
+
+#pragma once
+
+#include "../rod.hpp"
+
+namespace sim::coolant
+{
+
+class pipe : public sim::rod
+{
+	virtual const char* get_name() const;
+	virtual double get_k(sim::rod::val_t type) const;
+
+public:
+
+	virtual void update(double secs);
+};
+
+}
+
diff --git a/src/display.cpp b/src/display.cpp
new file mode 100644
index 0000000..b92ec98
--- /dev/null
+++ b/src/display.cpp
@@ -0,0 +1,49 @@
+
+#include "display.hpp"
+
+#include <curses.h>
+
+void display::draw_text(int x, int y, const char* str)
+{
+	for(int i = 0;; i++)
+	{
+		const char* start = str;
+		char c = (str++)[0];
+
+		while(c != '\n' && c != '\0')
+		{
+			c = (str++)[0];
+		}
+
+		mvaddnstr(x + i, y, start, (size_t)(str - start));
+
+		if(c == '\0') return;
+	}
+}
+
+void display::draw_box(int x, int y, int h, int w)
+{
+	mvaddch(x, y, '+');
+
+	for(int i = 0; i < w - 2; i++)
+	{
+		addch('-');
+	}
+
+	addch('+');
+
+	for(int i = 0; i < h - 2; i++)
+	{
+		mvaddch(x + i + 1, y, '|');
+		mvaddch(x + i + 1, y + w - 1, '|');
+	}
+	
+	mvaddch(x + h - 1, y, '+');
+
+	for(int i = 0; i < w - 2; i++)
+	{
+		addch('-');
+	}
+
+	addch('+');
+}
diff --git a/src/display.hpp b/src/display.hpp
new file mode 100644
index 0000000..be126e3
--- /dev/null
+++ b/src/display.hpp
@@ -0,0 +1,11 @@
+
+#pragma once
+
+namespace display
+{
+
+void draw_text(int x, int y, const char* str);
+void draw_box(int x, int y, int h, int w);
+
+}
+
diff --git a/src/fuel/fuel_rod.cpp b/src/fuel/fuel_rod.cpp
new file mode 100644
index 0000000..7c63860
--- /dev/null
+++ b/src/fuel/fuel_rod.cpp
@@ -0,0 +1,49 @@
+
+#include "fuel_rod.hpp"
+
+using namespace sim::fuel;
+
+fuel_rod::fuel_rod(double fuel, double mass) : s(fuel, mass)
+{
+
+}
+
+void fuel_rod::display(std::ostream& o) const
+{
+	o << "Fuel: " << s.get_fuel() << " / " << s.get_mass() << "\n";
+	o << "Energy: " << s.get_energy() << "\n";
+}
+
+const char* fuel_rod::get_name() const
+{
+	return "Fuel";
+}
+
+double fuel_rod::get_k(sim::rod::val_t type) const
+{
+	switch(type)
+	{
+	case val_t::HEAT:
+		return 1.0 / 16.0;
+	case val_t::N_SLOW:
+		return 1.0 / 4.0;
+	case val_t::N_FAST:
+		return 1.0 / 2.0;
+	}
+
+	return 0;
+}
+
+void fuel_rod::update(double secs)
+{
+	update_rod();
+	
+	s.add_slow_neutrons(vals[val_t::N_SLOW]);
+
+	vals[val_t::HEAT] += s.extract_energy() / s.get_mass();
+	vals[val_t::N_FAST] += s.extract_fast_neutrons();
+	vals[val_t::N_SLOW] = 0;
+	
+	s.update(secs);
+}
+
diff --git a/src/fuel/fuel_rod.hpp b/src/fuel/fuel_rod.hpp
new file mode 100644
index 0000000..8d52313
--- /dev/null
+++ b/src/fuel/fuel_rod.hpp
@@ -0,0 +1,26 @@
+
+#pragma once
+
+#include "sample.hpp"
+#include "../rod.hpp"
+
+namespace sim::fuel
+{
+
+class fuel_rod : public sim::rod
+{
+	sample s;
+	
+	virtual const char* get_name() const;
+	virtual double get_k(sim::rod::val_t type) const;
+	virtual void display(std::ostream& o) const;
+	
+public:
+
+	fuel_rod(double fuel, double mass);
+	
+	virtual void update(double secs);
+};
+
+}
+
diff --git a/src/half_life.hpp b/src/fuel/half_life.hpp
similarity index 89%
rename from src/half_life.hpp
rename to src/fuel/half_life.hpp
index a2a1ee5..c326e2b 100644
--- a/src/half_life.hpp
+++ b/src/fuel/half_life.hpp
@@ -3,7 +3,7 @@
 
 #include <cmath>
 
-namespace sim::half_life
+namespace sim::fuel::half_life
 {
 
 const double Te_135 = 19;
diff --git a/src/sample.cpp b/src/fuel/sample.cpp
similarity index 95%
rename from src/sample.cpp
rename to src/fuel/sample.cpp
index 3757651..98e1611 100644
--- a/src/sample.cpp
+++ b/src/fuel/sample.cpp
@@ -2,7 +2,7 @@
 #include "sample.hpp"
 #include "half_life.hpp"
 
-using namespace sim;
+using namespace sim::fuel;
 
 static const double Xe_135_M = 1e4;
 static const double NEUTRON_BG = 1e-10;
@@ -17,7 +17,7 @@ void sample::update(double secs)
 {
 	double m;
 
-	// simulate waste and extract products
+	// sim::fuelulate waste and extract products
 	waste.update(secs);
 	fast_neutrons += waste.extract_neutrons();
 	energy += waste.extract_energy();
@@ -49,7 +49,7 @@ void sample::update(double secs)
 	if(neutrons_xenon > xe_135) neutrons_xenon = xe_135;
 	if(neutrons_iodine > i_135) neutrons_iodine = i_135;
 
-	// simulate fuel use
+	// sim::fuelulate fuel use
 	fuel -= neutrons_fuel;
 	energy += neutrons_fuel;
 	fast_neutrons += neutrons_fuel * 3;
diff --git a/src/sample.hpp b/src/fuel/sample.hpp
similarity index 87%
rename from src/sample.hpp
rename to src/fuel/sample.hpp
index 3a190e4..98e95e2 100644
--- a/src/sample.hpp
+++ b/src/fuel/sample.hpp
@@ -5,12 +5,12 @@
 
 #include <ostream>
 
-namespace sim
+namespace sim::fuel
 {
 
 class sample
 {
-	sim::waste waste;
+	sim::fuel::waste waste;
 	
 	double fuel = 0;
 	double i_135 = 0;
@@ -35,6 +35,7 @@ public:
 	
 	constexpr double get_fuel() const { return fuel; }
 	constexpr double get_mass() const { return mass; }
+	constexpr double get_energy() const { return energy; }
 
 	double get_volume() const;
 
@@ -45,6 +46,5 @@ public:
 	}
 };
 
-
 }
 
diff --git a/src/waste.cpp b/src/fuel/waste.cpp
similarity index 96%
rename from src/waste.cpp
rename to src/fuel/waste.cpp
index 2750b4b..367f9dd 100644
--- a/src/waste.cpp
+++ b/src/fuel/waste.cpp
@@ -2,7 +2,7 @@
 #include "waste.hpp"
 #include "half_life.hpp"
 
-using namespace sim;
+using namespace sim::fuel;
 
 void waste::update(double secs)
 {
diff --git a/src/waste.hpp b/src/fuel/waste.hpp
similarity index 93%
rename from src/waste.hpp
rename to src/fuel/waste.hpp
index 5cd4bd1..3bd4a8e 100644
--- a/src/waste.hpp
+++ b/src/fuel/waste.hpp
@@ -1,7 +1,7 @@
 
 #pragma once
 
-namespace sim
+namespace sim::fuel
 {
 
 class waste
diff --git a/src/fuel_rod.cpp b/src/fuel_rod.cpp
deleted file mode 100644
index 07b1320..0000000
--- a/src/fuel_rod.cpp
+++ /dev/null
@@ -1,61 +0,0 @@
-
-#include "fuel_rod.hpp"
-
-using namespace sim;
-
-fuel_rod::fuel_rod(double f, double m) : fuel(f, m)
-{
-
-}
-
-void fuel_rod::update(double secs)
-{
-	double n = fuel.extract_fast_neutrons();
-	double n_slow = n * 0.5 * reactivity;
-	fuel.add_slow_neutrons(n_slow);
-	neutrons_absorbed += n * 0.5 * (1 - reactivity);
-	neutrons_free += n_slow;
-	
-	fuel.update(secs);
-	
-
-	temperature += fuel.extract_energy() / fuel.get_mass();
-}
-
-void fuel_rod::add_neutrons(double amount)
-{
-	fuel.add_slow_neutrons(amount);
-}
-
-double fuel_rod::extract_free_neutrons()
-{
-	double v = neutrons_free;
-	neutrons_free = 0;
-	return v;
-}
-
-double fuel_rod::extract_heat(double k, double o)
-{
-	double v = k * (temperature - o);
-	temperature -= v;
-	return v;
-}
-
-void fuel_rod::add_heat(double amount)
-{
-	temperature += amount;
-}
-
-void fuel_rod::set_reactivity(double v)
-{
-	reactivity = v;
-}
-
-void fuel_rod::display(std::ostream& o) const
-{
-	o << "Temperature: " << temperature << "\n";
-	o << "Reactivity: " << reactivity << "\n";
-	o << "Fuel: " << fuel.get_fuel() << " / " << fuel.get_mass() << "\n";
-	o << "Neutrons:\n  Absorbed: " << neutrons_absorbed << "\n  Free: " << neutrons_free << "\n";
-}
-
diff --git a/src/fuel_rod.hpp b/src/fuel_rod.hpp
deleted file mode 100644
index 8e6055b..0000000
--- a/src/fuel_rod.hpp
+++ /dev/null
@@ -1,44 +0,0 @@
-
-#pragma once
-
-#include "sample.hpp"
-
-namespace sim
-{
-
-class fuel_rod
-{
-	sample fuel;
-	
-	double reactivity = 0;
-	double temperature = 0;
-	double neutrons_absorbed = 0;
-	double neutrons_free = 0;
-
-	void display(std::ostream& o) const;
-
-public:
-
-	fuel_rod(double fuel, double mass);
-	fuel_rod() : fuel_rod(0, 0) {};
-
-	void update(double secs);
-	void set_reactivity(double amount);
-	void add_neutrons(double amount);
-	void add_heat(double amount);
-
-	constexpr double get_temperature() const { return temperature; }
-	constexpr double get_reactivity() const { return reactivity; }
-
-	double extract_free_neutrons();
-	double extract_heat(double k, double o);
-
-	friend std::ostream& operator<<(std::ostream& o, const fuel_rod& fr)
-	{
-		fr.display(o);
-		return o;
-	}
-};
-
-};
-
diff --git a/src/main.cpp b/src/main.cpp
index d50bbf3..77c1661 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,55 +1,14 @@
 
 #include "reactor.hpp"
+#include "control/control_rod.hpp"
+#include "fuel/fuel_rod.hpp"
+#include "coolant/pipe.hpp"
+#include "display.hpp"
 
 #include <sstream>
 #include <unistd.h>
 #include <curses.h>
 
-void draw_text(int x, int y, const char* str)
-{
-	for(int i = 0;; i++)
-	{
-		const char* start = str;
-		char c = (str++)[0];
-
-		while(c != '\n' && c != '\0')
-		{
-			c = (str++)[0];
-		}
-
-		mvaddnstr(x + i, y, start, (size_t)(str - start));
-
-		if(c == '\0') return;
-	}
-}
-
-void draw_box(int x, int y, int h, int w)
-{
-	mvaddch(x, y, '+');
-
-	for(int i = 0; i < w - 2; i++)
-	{
-		addch('-');
-	}
-
-	addch('+');
-
-	for(int i = 0; i < h - 2; i++)
-	{
-		mvaddch(x + i + 1, y, '|');
-		mvaddch(x + i + 1, y + w - 1, '|');
-	}
-	
-	mvaddch(x + h - 1, y, '+');
-
-	for(int i = 0; i < w - 2; i++)
-	{
-		addch('-');
-	}
-
-	addch('+');
-}
-
 int main()
 {
 	initscr();
@@ -59,7 +18,12 @@ int main()
 	nodelay(stdscr, TRUE);
 	curs_set(0);
 	
-	sim::reactor reactor(5, {100, 200});
+	sim::reactor<2, 2> reactor({
+		new sim::fuel::fuel_rod(100, 400),		new sim::fuel::fuel_rod(100, 400),
+		new sim::control::control_rod(1000),	new sim::coolant::pipe()
+	});
+
+	((sim::control::control_rod*)reactor.rods[0][1])->set_reactivity(0.99);
 
 	for(;;)
 	{
@@ -69,22 +33,22 @@ int main()
 		}
 
 		erase();
-		draw_text(1, 0, "Reactor Core:");
+		display::draw_text(1, 0, "Reactor Core:");
 
 		const int X = 3, Y = 4;
 		const int W = 32, H = 8;
 
-		for(int x = 0; x < reactor.get_size(); x++)
-		for(int y = 0; y < reactor.get_size(); y++)
+		for(int x = 0; x < reactor.width; x++)
+		for(int y = 0; y < reactor.height; y++)
 		{
 			std::stringstream ss;
-			reactor.display(ss, x, y);
+			ss << *reactor.rods[x][y];
 			
 			int px = X + (H - 1) * y;
 			int py = Y + (W - 1) * x;
 
-			draw_text(px + 1, py + 2, ss.str().c_str());
-			draw_box(px, py, H, W);
+			display::draw_text(px + 1, py + 2, ss.str().c_str());
+			display::draw_box(px, py, H, W);
 		}
 
 		refresh();
diff --git a/src/reactor.cpp b/src/reactor.cpp
deleted file mode 100644
index ad28291..0000000
--- a/src/reactor.cpp
+++ /dev/null
@@ -1,58 +0,0 @@
-
-#include "reactor.hpp"
-
-#include <iostream>
-#include <iomanip>
-
-using namespace sim;
-
-reactor::reactor(int size, fuel_rod fr)
-{
-	this->size = size;
-	rods.resize(size * size, fr);
-
-	rods[2].set_reactivity(1);
-}
-
-static const double HEAT_K = 1.0/64.0;
-
-void reactor::update(double secs)
-{
-	for(int y = 0; y < size; y++)
-	for(int x = 0; x < size; x++)
-	{
-		fuel_rod& fr = rods[get_id(x, y)];
-		fr.update(secs);
-
-		const int id_os[] = {
-			get_id(x - 1, y),
-			get_id(x, y - 1),
-			get_id(x + 1, y),
-			get_id(x, y + 1)
-		};
-		
-		const double neutrons = fr.extract_free_neutrons();
-
-		for(const int id_o : id_os)
-		{
-			if(id_o == -1) continue;
-
-
-			fuel_rod& fr_o = rods[id_o];
-			fr_o.add_heat(fr.extract_heat(HEAT_K * secs, fr_o.get_temperature()));
-			fr_o.add_neutrons(neutrons / 4);
-		}
-	}
-}
-
-int reactor::get_id(int x, int y) const
-{
-	if(x < 0 || y < 0 || x >= size || y >= size) return -1;
-	return y * size + x;
-}
-
-void reactor::display(std::ostream& o, int x, int y) const
-{
-	o << rods[get_id(x, y)];
-}
-
diff --git a/src/reactor.hpp b/src/reactor.hpp
index 3fa7673..87aa5ad 100644
--- a/src/reactor.hpp
+++ b/src/reactor.hpp
@@ -1,30 +1,58 @@
 
 #pragma once
 
-#include "fuel_rod.hpp"
+#include "rod.hpp"
 
-#include <vector>
+#include <array>
 
 namespace sim
 {
 
-class reactor
+template <int W, int H>
+struct reactor
 {
-	std::vector<fuel_rod> rods;
+	const static int width = W;
+	const static int height = H;
+	
+	std::array<std::array<sim::rod*, H>, W> rods;
 
-	int size;
-	long update_count = 0;
+	reactor(std::array<sim::rod*, W * H> rods)
+	{
+		for(int y = 0; y < H; y++)
+		for(int x = 0; x < W; x++)
+		{
+			this->rods[x][y] = rods[y * W + x];
+		}
+	}
 
-	int get_id(int x, int y) const;
+	void update(double secs)
+	{
+		// do interactions
+		for(int x = 1; x < W; x++)
+		{
+			rods[x][0]->interact(rods[x - 1][0]);
+		}
 
-public:
+		for(int y = 1; y < H; y++)
+		{
+			rods[0][y]->interact(rods[0][y - 1]);
+		}
 
-	reactor(int radius, fuel_rod fr);
+		for(int y = 1; y < H; y++)
+		for(int x = 1; x < W; x++)
+		{
+			rod* r = rods[x][y];
+			r->interact(rods[x - 1][y]);
+			r->interact(rods[x][y - 1]);
+		}
 
-	void update(double secs);
-	void display(std::ostream& o, int x, int y) const;
-
-	constexpr int get_size() const { return size; }
+		// do updates
+		for(int y = 0; y < H; y++)
+		for(int x = 0; x < W; x++)
+		{
+			rods[x][y]->update(secs);
+		}
+	}
 };
 
 }
diff --git a/src/rod.cpp b/src/rod.cpp
new file mode 100644
index 0000000..2300f7b
--- /dev/null
+++ b/src/rod.cpp
@@ -0,0 +1,46 @@
+
+#include "rod.hpp"
+
+using namespace sim;
+
+double rod::get(val_t type) const
+{
+	return vals[type];
+}
+
+void rod::add(val_t type, double v)
+{
+	vals_in[type] += v;
+}
+
+double rod::extract(val_t type, double k, double o)
+{
+	double v = k * get_k(type) * 0.5 * (get(type) - o);
+	vals_in[type] -= v;
+	return v;
+}
+
+void rod::interact(rod* o)
+{
+	for(int i = 0; i < rod::VAL_N; i++)
+	{
+		val_t v = (val_t)i;
+		add(v, o->extract(v, get_k(v), get(v)));
+	}
+}
+
+void rod::update_rod()
+{
+	for(int i = 0; i < rod::VAL_N; i++)
+	{
+		val_t v = (val_t)i;
+		vals[v] += vals_in[v];
+		vals_in[v] = 0;
+	}
+}
+
+void rod::display(std::ostream& o) const
+{
+
+}
+
diff --git a/src/rod.hpp b/src/rod.hpp
new file mode 100644
index 0000000..c8f06a8
--- /dev/null
+++ b/src/rod.hpp
@@ -0,0 +1,52 @@
+
+#pragma once
+
+#include <ostream>
+
+namespace sim
+{
+
+class rod
+{
+public:
+
+	static const int VAL_N = 3;
+	
+	enum val_t
+	{
+		HEAT = 0,
+		N_SLOW = 1,
+		N_FAST = 2
+	};
+
+	virtual void interact(rod* o);
+	virtual void update(double secs) = 0;
+	virtual void add(val_t type, double v);
+	virtual double extract(val_t type, double k, double o);
+	virtual double get(val_t type) const;
+
+	friend std::ostream& operator<<(std::ostream& o, const rod& r)
+	{
+		o << "Name: " << r.get_name() << "\n";
+		r.display(o);
+		o << "Heat: " << r.get(val_t::HEAT) << "\n";
+		o << "Fast: " << r.get(val_t::N_FAST) << "\n";
+		o << "Slow: " << r.get(val_t::N_SLOW) << "\n";
+
+		return o;
+	}
+
+protected:
+
+	double vals_in[VAL_N] = {0};
+	double vals[VAL_N] = {0};
+
+	virtual void display(std::ostream& o) const;
+	virtual double get_k(val_t type) const = 0;
+	virtual const char* get_name() const = 0;
+
+	void update_rod();
+};
+
+}
+