diff --git a/src/coolant/fluid_t.hpp b/src/coolant/fluid_t.hpp
index 87fa23e..e153ca2 100644
--- a/src/coolant/fluid_t.hpp
+++ b/src/coolant/fluid_t.hpp
@@ -12,9 +12,18 @@ struct fluid_t
 	const double gPmol; // g/mol
 	const double jPg; // J/g		latent heat of vaporisation
 	const double jPgk; // J/g/K		heat capacity
+	const double bubble_speed; // m/s
+	
 	const coolant::vapor_pressure vapor_pressure;
 	
-	constexpr fluid_t(double gPl, double gPmol, double jPg, double jPgk, coolant::vapor_pressure vapor_pressure) : gPl(gPl), gPmol(gPmol), jPg(jPg), jPgk(jPgk), vapor_pressure(vapor_pressure) { }	
+	constexpr fluid_t(double gPl, double gPmol, double jPg, double jPgk, double bubble_speed, coolant::vapor_pressure vapor_pressure) :
+			gPl(gPl), gPmol(gPmol),
+			jPg(jPg), jPgk(jPgk), 
+			vapor_pressure(vapor_pressure),
+	   		bubble_speed(bubble_speed)
+	{
+
+	}	
 
 	constexpr double g_to_mol(double g) const { return g / gPmol; }
 	constexpr double mol_to_g(double mol) const { return mol * gPmol; }
@@ -24,7 +33,7 @@ struct fluid_t
 	constexpr double l_to_mol(double l) const { return g_to_mol(l_to_g(l)); }
 };
 
-constexpr const fluid_t WATER = fluid_t(1000, 18, 2257, 4.1816, {8.07131, 1730.63, 233.426});
+constexpr const fluid_t WATER = fluid_t(1000, 18, 2257, 4.1816, 0.3, {8.07131, 1730.63, 233.426});
 
 }
 
diff --git a/src/graphics/window.cpp b/src/graphics/window.cpp
index 32bdfba..6ce2463 100644
--- a/src/graphics/window.cpp
+++ b/src/graphics/window.cpp
@@ -26,7 +26,10 @@ static mesh MeshScene, MeshText;
 
 void GLAPIENTRY cb_debug_message(GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei length, const GLchar* message, const void* userParam)
 {
-	std::cout << "GL CALLBACK: " << message << "\n";
+	if(severity != GL_DEBUG_SEVERITY_NOTIFICATION)
+	{
+		std::cout << "GL CALLBACK: " << message << "\n";
+	}
 }
 
 void window::create()
@@ -90,10 +93,10 @@ void window::create()
 	glViewport(0, 0, 800, 600);
 }
 
-void window::loop()
+void window::loop(const char* str)
 {
 	MeshText.bind();
-	font::generate(MeshText, "Hello, World!\nThis is cool!\n=)", 0.1);
+	font::generate(MeshText, str, 0.1);
 
 	glm::mat4 mat_projection = glm::perspective(glm::radians(90.0f), 1.0f, 0.01f, 20.f);
 	glUniformMatrix4fv(shader::gl_projection, 1, false, &mat_projection[0][0]);
diff --git a/src/graphics/window.hpp b/src/graphics/window.hpp
index 3b031fd..a55c2a3 100644
--- a/src/graphics/window.hpp
+++ b/src/graphics/window.hpp
@@ -8,7 +8,7 @@ namespace sim::graphics::window
 
 void create();
 bool should_close();
-void loop();
+void loop(const char* str);
 void destroy();
 void close();
 
diff --git a/src/main.cpp b/src/main.cpp
index 2a6c134..dd32fde 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -2,7 +2,7 @@
 #include <sys/time.h>
 
 #include <random>
-#include <iostream>
+#include <sstream>
 #include <cmath>
 
 #include "reactor/builder.hpp"
@@ -31,6 +31,21 @@ int main()
 {
 	std::random_device rd;
 	std::mt19937 rand(rd());
+	
+	sim::reactor::coolant::vessel vessel(8, 10, 300, sim::coolant::WATER);
+	sim::reactor::reactor<5, 5> reactor = sim::reactor::builder<5, 5>(
+		sim::reactor::fuel::fuel_rod(2000, 4000),
+		sim::reactor::control::control_rod(vessel, 10000, 1),
+		sim::reactor::coolant::pipe(vessel), {
+			"#C#C#",
+			"CFCFC",
+			"#C#C#",
+			"CFCFC",
+			"#C#C#"
+		});
+	
+	sim::coolant::valve<sim::reactor::coolant::vessel> valve(vessel, 1, 500);
+	sim::coolant::pump<sim::reactor::coolant::vessel> pump(vessel, 1e4, 15);
 
 	graphics::window::create();
 
@@ -42,9 +57,18 @@ int main()
 		long passed = now - clock;
 		double dt = (double)passed / 1e6;
 		clock += passed;
+		
+		std::stringstream ss;
+
+		reactor.update(rand, dt);
+		pump.update(dt);
+		valve.update(dt);
+		vessel.update(dt);
+		
+		ss << "Reactor Vessel\n\n" << vessel;
 
 		graphics::camera::update(dt);
-		graphics::window::loop();
+		graphics::window::loop(ss.str().c_str());
 	}
 
 	graphics::window::destroy();
diff --git a/src/reactor/coolant/pipe.cpp b/src/reactor/coolant/pipe.cpp
index 3e7824e..e78810e 100644
--- a/src/reactor/coolant/pipe.cpp
+++ b/src/reactor/coolant/pipe.cpp
@@ -11,7 +11,7 @@ pipe::pipe(coolant::vessel& v)
 
 double pipe::get_k(val_t type) const
 {
-	return vessel->get_level() / vessel->get_volume() * 0.5;
+	return vessel->get_level() / vessel->get_volume() * (1 - vessel->get_void_ratio()) * 0.5;
 }
 
 void pipe::update(double secs)
diff --git a/src/reactor/coolant/vessel.cpp b/src/reactor/coolant/vessel.cpp
index 0e83547..fa2bbf0 100644
--- a/src/reactor/coolant/vessel.cpp
+++ b/src/reactor/coolant/vessel.cpp
@@ -2,17 +2,31 @@
 #include "vessel.hpp"
 #include "../../constants.hpp"
 #include "../../conversions/temperature.hpp"
+#include "../fuel/half_life.hpp"
 
 #include <cmath>
 
 using namespace sim::reactor::coolant;
 
-vessel::vessel(double level, double volume, sim::coolant::fluid_t fluid) : volume(volume), fluid(fluid)
+constexpr static double calc_cylinder(double h, double d)
 {
-	this->level = level;
+	double r = d / 2;
+	
+	return M_PI * r * r * h;
 }
 
-void vessel::update()
+vessel::vessel(double height, double diameter, double level, sim::coolant::fluid_t fluid) :
+		height(height),
+		diameter(diameter),
+		volume(calc_cylinder(height, diameter)),
+		fluid(fluid),
+		level(level),
+		bubble_hl(height * 0.5 / fluid.bubble_speed)
+{
+	
+}
+
+void vessel::update(double secs)
 {
 	double V = (volume - level) * 0.001;
 	double P = fluid.vapor_pressure.calc_p(heat);
@@ -46,6 +60,9 @@ void vessel::update()
 	steam = s;
 	level = fluid.g_to_l(l);
 	heat -= diff * fluid.jPg / (fluid.l_to_g(level) + steam) / fluid.jPgk;
+
+	if(diff > 0) steam_suspended += diff;
+	steam_suspended *= fuel::half_life::get(secs, bubble_hl);
 }
 
 double vessel::add_heat(double t1)
@@ -116,6 +133,7 @@ std::ostream& operator<<(std::ostream& o, const vessel& v)
 	o << "Steam: " << v.get_steam() << " g\n";
 	o << "Heat: " << v.get_heat() << " C\n";
 	o << "Pressure: " << (v.get_pressure() * 0.001) << " kPa\n";
+	o << "Void Ratio: " << (v.get_void_ratio() * 100) << " %\n";
 
 	return o;
 }
diff --git a/src/reactor/coolant/vessel.hpp b/src/reactor/coolant/vessel.hpp
index 13c2f6a..b9dbc5a 100644
--- a/src/reactor/coolant/vessel.hpp
+++ b/src/reactor/coolant/vessel.hpp
@@ -13,26 +13,34 @@ class vessel
 	double level; // litres
 	double heat = 0; // celcius
 	double steam = 0; // grams
+	double steam_suspended = 0; // grams
 
 public:
 	
+	const double height; // meters
+	const double diameter; // meters
 	const double volume; // litres
+	const double bubble_hl; // seconds
+
 	const sim::coolant::fluid_t fluid;
 
-	vessel(double level, double volume, sim::coolant::fluid_t fluid);
+	vessel(double height, double diameter, double level, sim::coolant::fluid_t fluid);
 
-	void update();
+	void update(double secs);
 	double add_heat(double amount);
 	double add_fluid(double amount, double heat);
 	double extract_steam(double dt, double a, double p2);
 
-	constexpr double get_volume() const { return volume; }
-	constexpr double get_level() const { return level; }
-	constexpr double get_heat() const { return heat; }
-	constexpr double get_steam() const { return steam; }
-	constexpr double get_mass() const { return fluid.l_to_g(level) + steam; }
+	constexpr double get_volume() const { return volume; } // litres
+	constexpr double get_level() const { return level; } // litres
+	constexpr double get_heat() const { return heat; } // celsius
+	constexpr double get_steam() const { return steam; } // grams
+	constexpr double get_mass() const { return fluid.l_to_g(level) + steam; } // grams
+	constexpr double get_steam_density() const { return steam / (volume - level); } // g/L
+	constexpr double get_steam_suspended() const { return steam_suspended; } // grams
+	constexpr double get_void_ratio() const { double s = steam_suspended / get_steam_density(); return s / (level + s); }
 	
-	double get_pressure() const;
+	double get_pressure() const; // pascals
 };
 
 }