Split radiation from nuclear reactor code

3 files changed, 403 insertions, 398 deletions

diff --git a/technic/init.lua b/technic/init.lua
index 70ad848..4464082 100644
--- a/technic/init.lua
+++ b/technic/init.lua
@@ -35,6 +35,9 @@ dofile(modpath.."/crafts.lua")
 -- Register functions
 dofile(modpath.."/register.lua")
 
+-- Radiation
+dofile(modpath.."/radiation.lua")
+
 -- Machines
 dofile(modpath.."/machines/init.lua")
 
diff --git a/technic/machines/HV/nuclear_reactor.lua b/technic/machines/HV/nuclear_reactor.lua
index 6477697..235d03c 100644
--- a/technic/machines/HV/nuclear_reactor.lua
+++ b/technic/machines/HV/nuclear_reactor.lua
@@ -365,401 +365,3 @@ minetest.register_node("technic:hv_nuclear_reactor_core_active", {
 technic.register_machine("HV", "technic:hv_nuclear_reactor_core",        technic.producer)
 technic.register_machine("HV", "technic:hv_nuclear_reactor_core_active", technic.producer)
 
---[[
-Radioactivity
-
-Radiation resistance represents the extent to which a material
-attenuates radiation passing through it; i.e., how good a radiation
-shield it is.  This is identified per node type.  For materials that
-exist in real life, the radiation resistance value that this system
-uses for a node type consisting of a solid cube of that material is the
-(approximate) number of halvings of ionising radiation that is achieved
-by a meter of the material in real life.  This is approximately
-proportional to density, which provides a good way to estimate it.
-Homogeneous mixtures of materials have radiation resistance computed
-by a simple weighted mean.  Note that the amount of attenuation that
-a material achieves in-game is not required to be (and is not) the
-same as the attenuation achieved in real life.
-
-Radiation resistance for a node type may be specified in the node
-definition, under the key "radiation_resistance".  As an interim
-measure, until node definitions widely include this, this code
-knows a bunch of values for particular node types in several mods,
-and values for groups of node types.  The node definition takes
-precedence if it specifies a value.  Nodes for which no value at
-all is known are taken to provide no radiation resistance at all;
-this is appropriate for the majority of node types.  Only node types
-consisting of a fairly homogeneous mass of material should report
-non-zero radiation resistance; anything with non-uniform geometry
-or complex internal structure should show no radiation resistance.
-Fractional resistance values are permitted.
---]]
-
-local rad_resistance_node = {
-	["default:brick"] = 13,
-	["default:bronzeblock"] = 45,
-	["default:clay"] = 15,
-	["default:coalblock"] = 9.6,
-	["default:cobble"] = 15,
-	["default:copperblock"] = 46,
-	["default:desert_cobble"] = 15,
-	["default:desert_sand"] = 10,
-	["default:desert_stone"] = 17,
-	["default:desert_stonebrick"] = 17,
-	["default:diamondblock"] = 24,
-	["default:dirt"] = 8.2,
-	["default:dirt_with_grass"] = 8.2,
-	["default:dirt_with_grass_footsteps"] = 8.2,
-	["default:dirt_with_snow"] = 8.2,
-	["default:glass"] = 17,
-	["default:goldblock"] = 170,
-	["default:gravel"] = 10,
-	["default:ice"] = 5.6,
-	["default:lava_flowing"] = 8.5,
-	["default:lava_source"] = 17,
-	["default:mese"] = 21,
-	["default:mossycobble"] = 15,
-	["default:nyancat"] = 1000,
-	["default:nyancat_rainbow"] = 1000,
-	["default:obsidian"] = 18,
-	["default:obsidian_glass"] = 18,
-	["default:sand"] = 10,
-	["default:sandstone"] = 15,
-	["default:sandstonebrick"] = 15,
-	["default:snowblock"] = 1.7,
-	["default:steelblock"] = 40,
-	["default:stone"] = 17,
-	["default:stone_with_coal"] = 16,
-	["default:stone_with_copper"] = 20,
-	["default:stone_with_diamond"] = 18,
-	["default:stone_with_gold"] = 34,
-	["default:stone_with_iron"] = 20,
-	["default:stone_with_mese"] = 17,
-	["default:stonebrick"] = 17,
-	["default:water_flowing"] = 2.8,
-	["default:water_source"] = 5.6,
-	["farming:desert_sand_soil"] = 10,
-	["farming:desert_sand_soil_wet"] = 10,
-	["farming:soil"] = 8.2,
-	["farming:soil_wet"] = 8.2,
-	["glooptest:akalin_crystal_glass"] = 21,
-	["glooptest:akalinblock"] = 40,
-	["glooptest:alatro_crystal_glass"] = 21,
-	["glooptest:alatroblock"] = 40,
-	["glooptest:amethystblock"] = 18,
-	["glooptest:arol_crystal_glass"] = 21,
-	["glooptest:crystal_glass"] = 21,
-	["glooptest:emeraldblock"] = 19,
-	["glooptest:heavy_crystal_glass"] = 21,
-	["glooptest:mineral_akalin"] = 20,
-	["glooptest:mineral_alatro"] = 20,
-	["glooptest:mineral_amethyst"] = 17,
-	["glooptest:mineral_arol"] = 20,
-	["glooptest:mineral_desert_coal"] = 16,
-	["glooptest:mineral_desert_iron"] = 20,
-	["glooptest:mineral_emerald"] = 17,
-	["glooptest:mineral_kalite"] = 20,
-	["glooptest:mineral_ruby"] = 18,
-	["glooptest:mineral_sapphire"] = 18,
-	["glooptest:mineral_talinite"] = 20,
-	["glooptest:mineral_topaz"] = 18,
-	["glooptest:reinforced_crystal_glass"] = 21,
-	["glooptest:rubyblock"] = 27,
-	["glooptest:sapphireblock"] = 27,
-	["glooptest:talinite_crystal_glass"] = 21,
-	["glooptest:taliniteblock"] = 40,
-	["glooptest:topazblock"] = 24,
-	["mesecons_extrawires:mese_powered"] = 21,
-	["moreblocks:cactus_brick"] = 13,
-	["moreblocks:cactus_checker"] = 8.5,
-	["moreblocks:circle_stone_bricks"] = 17,
-	["moreblocks:clean_glass"] = 17,
-	["moreblocks:coal_checker"] = 9.0,
-	["moreblocks:coal_glass"] = 17,
-	["moreblocks:coal_stone"] = 17,
-	["moreblocks:coal_stone_bricks"] = 17,
-	["moreblocks:glow_glass"] = 17,
-	["moreblocks:grey_bricks"] = 15,
-	["moreblocks:iron_checker"] = 11,
-	["moreblocks:iron_glass"] = 17,
-	["moreblocks:iron_stone"] = 17,
-	["moreblocks:iron_stone_bricks"] = 17,
-	["moreblocks:plankstone"] = 9.3,
-	["moreblocks:split_stone_tile"] = 15,
-	["moreblocks:split_stone_tile_alt"] = 15,
-	["moreblocks:stone_tile"] = 15,
-	["moreblocks:super_glow_glass"] = 17,
-	["moreblocks:tar"] = 7.0,
-	["moreblocks:wood_tile"] = 1.7,
-	["moreblocks:wood_tile_center"] = 1.7,
-	["moreblocks:wood_tile_down"] = 1.7,
-	["moreblocks:wood_tile_flipped"] = 1.7,
-	["moreblocks:wood_tile_full"] = 1.7,
-	["moreblocks:wood_tile_left"] = 1.7,
-	["moreblocks:wood_tile_right"] = 1.7,
-	["moreblocks:wood_tile_up"] = 1.7,
-	["moreores:mineral_mithril"] = 18,
-	["moreores:mineral_silver"] = 21,
-	["moreores:mineral_tin"] = 19,
-	["moreores:mithril_block"] = 26,
-	["moreores:silver_block"] = 53,
-	["moreores:tin_block"] = 37,
-	["snow:snow_brick"] = 2.8,
-	["technic:brass_block"] = 43,
-	["technic:carbon_steel_block"] = 40,
-	["technic:cast_iron_block"] = 40,
-	["technic:chernobylite_block"] = 40,
-	["technic:chromium_block"] = 37,
-	["technic:corium_flowing"] = 40,
-	["technic:corium_source"] = 80,
-	["technic:granite"] = 18,
-	["technic:lead_block"] = 80,
-	["technic:marble"] = 18,
-	["technic:marble_bricks"] = 18,
-	["technic:mineral_chromium"] = 19,
-	["technic:mineral_uranium"] = 71,
-	["technic:mineral_zinc"] = 19,
-	["technic:stainless_steel_block"] = 40,
-	["technic:zinc_block"] = 36,
-	["tnt:tnt"] = 11,
-	["tnt:tnt_burning"] = 11,
-}
-local rad_resistance_group = {
-	concrete = 16,
-	tree = 3.4,
-	uranium_block = 500,
-	wood = 1.7,
-}
-local cache_radiation_resistance = {}
-local function node_radiation_resistance(node_name)
-	local resistance = cache_radiation_resistance[node_name]
-	if resistance then
-		return resistance
-	end
-	local def = minetest.registered_nodes[node_name]
-	if not def then
-		cache_radiation_resistance[node_name] = 0
-		return 0
-	end
-	resistance = def.radiation_resistance or
-			rad_resistance_node[node_name]
-	if not resistance then
-		resistance = 0
-		for g, v in pairs(def.groups) do
-			if v > 0 and rad_resistance_group[g] then
-				resistance = resistance + rad_resistance_group[g]
-			end
-		end
-	end
-	resistance = math.sqrt(resistance)
-	cache_radiation_resistance[node_name] = resistance
-	return resistance
-end
-
-
---[[
-Radioactive nodes cause damage to nearby players.  The damage
-effect depends on the intrinsic strength of the radiation source,
-the distance between the source and the player, and the shielding
-effect of the intervening material.  These determine a rate of damage;
-total damage caused is the integral of this over time.
-
-In the absence of effective shielding, for a specific source the
-damage rate varies realistically in inverse proportion to the square
-of the distance.  (Distance is measured to the player's abdomen,
-not to the nominal player position which corresponds to the foot.)
-However, if the player is inside a non-walkable (liquid or gaseous)
-radioactive node, the nominal distance could go to zero, yielding
-infinite damage.  In that case, the player's body is displacing the
-radioactive material, so the effective distance should remain non-zero.
-We therefore apply a lower distance bound of sqrt(0.75), which is
-the maximum distance one can get from the node center within the node.
-
-A radioactive node is identified by being in the "radioactive" group,
-and the group value signifies the strength of the radiation source.
-The group value is the distance from a node at which an unshielded
-player will be damaged by 1 HP/s.  Or, equivalently, it is the square
-root of the damage rate in HP/s that an unshielded player one node
-away will take.
-
-Shielding is assessed by adding the shielding values of all nodes
-between the source node and the player, ignoring the source node itself.
-As in reality, shielding causes exponential attenuation of radiation.
-However, the effect is scaled down relative to real life.  A node with
-radiation resistance value R yields attenuation of sqrt(R) * 0.1 nepers.
-(In real life it would be about R * 0.69 nepers, by the definition
-of the radiation resistance values.)  The sqrt part of this formula
-scales down the differences between shielding types, reflecting the
-game's simplification of making expensive materials such as gold
-readily available in cubes.  The multiplicative factor in the
-formula scales down the difference between shielded and unshielded
-safe distances, avoiding the latter becoming impractically large.
-
-Damage is processed at rates down to 0.25 HP/s, which in the absence of
-shielding is attained at the distance specified by the "radioactive"
-group value.  Computed damage rates below 0.25 HP/s result in no
-damage at all to the player.  This gives the player an opportunity
-to be safe, and limits the range at which source/player interactions
-need to be considered.
---]]
-local abdomen_offset = 1
-local cache_scaled_shielding = {}
-local rad_dmg_cutoff = 0.25
-
-local function dmg_player(pos, o, strength)
-	local pl_pos = o:getpos()
-	pl_pos.y = pl_pos.y + abdomen_offset
-	local shielding = 0
-	local dist = vector.distance(pos, pl_pos)
-	for ray_pos in technic.trace_node_ray(pos,
-			vector.direction(pos, pl_pos), dist) do
-		local shield_name = minetest.get_node(ray_pos).name
-		shielding = shielding + node_radiation_resistance(shield_name) * 0.1
-	end
-	local dmg = (strength * strength) /
-		(math.max(0.75, dist * dist) * math.exp(shielding))
-	if dmg < rad_dmg_cutoff then return end
-	local dmg_int = math.floor(dmg)
-	-- The closer you are to getting one more damage point,
-	-- the more likely it will be added.
-	if math.random() < dmg - dmg_int then
-		dmg_int = dmg_int + 1
-	end
-	if dmg_int > 0 then
-		o:set_hp(math.max(o:get_hp() - dmg_int, 0))
-	end
-end
-
-local rad_dmg_mult_sqrt = math.sqrt(1 / rad_dmg_cutoff)
-local function dmg_abm(pos, node)
-	local strength = minetest.get_item_group(node.name, "radioactive")
-	local max_dist = strength * rad_dmg_mult_sqrt
-	for _, o in pairs(minetest.get_objects_inside_radius(pos,
-			max_dist + abdomen_offset)) do
-		if o:is_player() then
-			dmg_player(pos, o, strength)
-		end
-	end
-end
-
-
-if minetest.setting_getbool("enable_damage") then
-	minetest.register_abm({
-		nodenames = {"group:radioactive"},
-		interval = 1,
-		chance = 1,
-		action = dmg_abm,
-	})
-end
-
--- Radioactive materials that can result from destroying a reactor
-local griefing = technic.config:get_bool("enable_corium_griefing")
-
-for _, state in pairs({"flowing", "source"}) do
-	minetest.register_node("technic:corium_"..state, {
-		description = S(state == "source" and "Corium Source" or "Flowing Corium"),
-		drawtype = (state == "source" and "liquid" or "flowingliquid"),
-		[state == "source" and "tiles" or "special_tiles"] = {{
-			name = "technic_corium_"..state.."_animated.png",
-			animation = {
-				type = "vertical_frames",
-				aspect_w = 16,
-				aspect_h = 16,
-				length = 3.0,
-			},
-		}},
-		paramtype = "light",
-		paramtype2 = (state == "flowing" and "flowingliquid" or nil),
-		light_source = (state == "source" and 8 or 5),
-		walkable = false,
-		pointable = false,
-		diggable = false,
-		buildable_to = true,
-		drop = "",
-		drowning = 1,
-		liquidtype = state,
-		liquid_alternative_flowing = "technic:corium_flowing",
-		liquid_alternative_source = "technic:corium_source",
-		liquid_viscosity = LAVA_VISC,
-		liquid_renewable = false,
-		damage_per_second = 6,
-		post_effect_color = {a=192, r=80, g=160, b=80},
-		groups = {
-			liquid = 2,
-			hot = 3,
-			igniter = (griefing and 1 or 0),
-			radioactive = (state == "source" and 16 or 8),
-			not_in_creative_inventory = (state == "flowing" and 1 or nil),
-		},
-	})
-end
-
-if rawget(_G, "bucket") and bucket.register_liquid then
-	bucket.register_liquid(
-		"technic:corium_source",
-		"technic:corium_flowing",
-		"technic:bucket_corium",
-		"technic_bucket_corium.png",
-		"Corium Bucket"
-	)
-end
-
-minetest.register_node("technic:chernobylite_block", {
-        description = S("Chernobylite Block"),
-	tiles = {"technic_chernobylite_block.png"},
-	is_ground_content = true,
-	groups = {cracky=1, radioactive=6, level=2},
-	sounds = default.node_sound_stone_defaults(),
-	light_source = 2,
-})
-
-minetest.register_abm({
-	nodenames = {"group:water"},
-	neighbors = {"technic:corium_source"},
-	interval = 1,
-	chance = 1,
-	action = function(pos, node)
-		minetest.remove_node(pos)
-	end,
-})
-
-minetest.register_abm({
-	nodenames = {"technic:corium_flowing"},
-	neighbors = {"group:water"},
-	interval = 1,
-	chance = 1,
-	action = function(pos, node)
-		minetest.set_node(pos, {name="technic:chernobylite_block"})
-	end,
-})
-
-minetest.register_abm({
-	nodenames = {"technic:corium_flowing"},
-	interval = 5,
-	chance = (griefing and 10 or 1),
-	action = function(pos, node)
-		minetest.set_node(pos, {name="technic:chernobylite_block"})
-	end,
-})
-
-if griefing then
-	minetest.register_abm({
-		nodenames = {"technic:corium_source", "technic:corium_flowing"},
-		interval = 4,
-		chance = 4,
-		action = function(pos, node)
-			for _, offset in ipairs({
-				vector.new(1,0,0),
-				vector.new(-1,0,0),
-				vector.new(0,0,1),
-				vector.new(0,0,-1),
-				vector.new(0,-1,0),
-			}) do
-				if math.random(8) == 1 then
-					minetest.dig_node(vector.add(pos, offset))
-				end
-			end
-		end,
-	})
-end
-
diff --git a/technic/radiation.lua b/technic/radiation.lua
new file mode 100644
index 0000000..2dec38b
--- /dev/null
+++ b/technic/radiation.lua
@@ -0,0 +1,400 @@
+--[[
+Radioactivity
+
+Radiation resistance represents the extent to which a material
+attenuates radiation passing through it; i.e., how good a radiation
+shield it is.  This is identified per node type.  For materials that
+exist in real life, the radiation resistance value that this system
+uses for a node type consisting of a solid cube of that material is the
+(approximate) number of halvings of ionising radiation that is achieved
+by a meter of the material in real life.  This is approximately
+proportional to density, which provides a good way to estimate it.
+Homogeneous mixtures of materials have radiation resistance computed
+by a simple weighted mean.  Note that the amount of attenuation that
+a material achieves in-game is not required to be (and is not) the
+same as the attenuation achieved in real life.
+
+Radiation resistance for a node type may be specified in the node
+definition, under the key "radiation_resistance".  As an interim
+measure, until node definitions widely include this, this code
+knows a bunch of values for particular node types in several mods,
+and values for groups of node types.  The node definition takes
+precedence if it specifies a value.  Nodes for which no value at
+all is known are taken to provide no radiation resistance at all;
+this is appropriate for the majority of node types.  Only node types
+consisting of a fairly homogeneous mass of material should report
+non-zero radiation resistance; anything with non-uniform geometry
+or complex internal structure should show no radiation resistance.
+Fractional resistance values are permitted.
+--]]
+
+local S = technic.getter
+
+local rad_resistance_node = {
+	["default:brick"] = 13,
+	["default:bronzeblock"] = 45,
+	["default:clay"] = 15,
+	["default:coalblock"] = 9.6,
+	["default:cobble"] = 15,
+	["default:copperblock"] = 46,
+	["default:desert_cobble"] = 15,
+	["default:desert_sand"] = 10,
+	["default:desert_stone"] = 17,
+	["default:desert_stonebrick"] = 17,
+	["default:diamondblock"] = 24,
+	["default:dirt"] = 8.2,
+	["default:dirt_with_grass"] = 8.2,
+	["default:dirt_with_grass_footsteps"] = 8.2,
+	["default:dirt_with_snow"] = 8.2,
+	["default:glass"] = 17,
+	["default:goldblock"] = 170,
+	["default:gravel"] = 10,
+	["default:ice"] = 5.6,
+	["default:lava_flowing"] = 8.5,
+	["default:lava_source"] = 17,
+	["default:mese"] = 21,
+	["default:mossycobble"] = 15,
+	["default:nyancat"] = 1000,
+	["default:nyancat_rainbow"] = 1000,
+	["default:obsidian"] = 18,
+	["default:obsidian_glass"] = 18,
+	["default:sand"] = 10,
+	["default:sandstone"] = 15,
+	["default:sandstonebrick"] = 15,
+	["default:snowblock"] = 1.7,
+	["default:steelblock"] = 40,
+	["default:stone"] = 17,
+	["default:stone_with_coal"] = 16,
+	["default:stone_with_copper"] = 20,
+	["default:stone_with_diamond"] = 18,
+	["default:stone_with_gold"] = 34,
+	["default:stone_with_iron"] = 20,
+	["default:stone_with_mese"] = 17,
+	["default:stonebrick"] = 17,
+	["default:water_flowing"] = 2.8,
+	["default:water_source"] = 5.6,
+	["farming:desert_sand_soil"] = 10,
+	["farming:desert_sand_soil_wet"] = 10,
+	["farming:soil"] = 8.2,
+	["farming:soil_wet"] = 8.2,
+	["glooptest:akalin_crystal_glass"] = 21,
+	["glooptest:akalinblock"] = 40,
+	["glooptest:alatro_crystal_glass"] = 21,
+	["glooptest:alatroblock"] = 40,
+	["glooptest:amethystblock"] = 18,
+	["glooptest:arol_crystal_glass"] = 21,
+	["glooptest:crystal_glass"] = 21,
+	["glooptest:emeraldblock"] = 19,
+	["glooptest:heavy_crystal_glass"] = 21,
+	["glooptest:mineral_akalin"] = 20,
+	["glooptest:mineral_alatro"] = 20,
+	["glooptest:mineral_amethyst"] = 17,
+	["glooptest:mineral_arol"] = 20,
+	["glooptest:mineral_desert_coal"] = 16,
+	["glooptest:mineral_desert_iron"] = 20,
+	["glooptest:mineral_emerald"] = 17,
+	["glooptest:mineral_kalite"] = 20,
+	["glooptest:mineral_ruby"] = 18,
+	["glooptest:mineral_sapphire"] = 18,
+	["glooptest:mineral_talinite"] = 20,
+	["glooptest:mineral_topaz"] = 18,
+	["glooptest:reinforced_crystal_glass"] = 21,
+	["glooptest:rubyblock"] = 27,
+	["glooptest:sapphireblock"] = 27,
+	["glooptest:talinite_crystal_glass"] = 21,
+	["glooptest:taliniteblock"] = 40,
+	["glooptest:topazblock"] = 24,
+	["mesecons_extrawires:mese_powered"] = 21,
+	["moreblocks:cactus_brick"] = 13,
+	["moreblocks:cactus_checker"] = 8.5,
+	["moreblocks:circle_stone_bricks"] = 17,
+	["moreblocks:clean_glass"] = 17,
+	["moreblocks:coal_checker"] = 9.0,
+	["moreblocks:coal_glass"] = 17,
+	["moreblocks:coal_stone"] = 17,
+	["moreblocks:coal_stone_bricks"] = 17,
+	["moreblocks:glow_glass"] = 17,
+	["moreblocks:grey_bricks"] = 15,
+	["moreblocks:iron_checker"] = 11,
+	["moreblocks:iron_glass"] = 17,
+	["moreblocks:iron_stone"] = 17,
+	["moreblocks:iron_stone_bricks"] = 17,
+	["moreblocks:plankstone"] = 9.3,
+	["moreblocks:split_stone_tile"] = 15,
+	["moreblocks:split_stone_tile_alt"] = 15,
+	["moreblocks:stone_tile"] = 15,
+	["moreblocks:super_glow_glass"] = 17,
+	["moreblocks:tar"] = 7.0,
+	["moreblocks:wood_tile"] = 1.7,
+	["moreblocks:wood_tile_center"] = 1.7,
+	["moreblocks:wood_tile_down"] = 1.7,
+	["moreblocks:wood_tile_flipped"] = 1.7,
+	["moreblocks:wood_tile_full"] = 1.7,
+	["moreblocks:wood_tile_left"] = 1.7,
+	["moreblocks:wood_tile_right"] = 1.7,
+	["moreblocks:wood_tile_up"] = 1.7,
+	["moreores:mineral_mithril"] = 18,
+	["moreores:mineral_silver"] = 21,
+	["moreores:mineral_tin"] = 19,
+	["moreores:mithril_block"] = 26,
+	["moreores:silver_block"] = 53,
+	["moreores:tin_block"] = 37,
+	["snow:snow_brick"] = 2.8,
+	["technic:brass_block"] = 43,
+	["technic:carbon_steel_block"] = 40,
+	["technic:cast_iron_block"] = 40,
+	["technic:chernobylite_block"] = 40,
+	["technic:chromium_block"] = 37,
+	["technic:corium_flowing"] = 40,
+	["technic:corium_source"] = 80,
+	["technic:granite"] = 18,
+	["technic:lead_block"] = 80,
+	["technic:marble"] = 18,
+	["technic:marble_bricks"] = 18,
+	["technic:mineral_chromium"] = 19,
+	["technic:mineral_uranium"] = 71,
+	["technic:mineral_zinc"] = 19,
+	["technic:stainless_steel_block"] = 40,
+	["technic:zinc_block"] = 36,
+	["tnt:tnt"] = 11,
+	["tnt:tnt_burning"] = 11,
+}
+local rad_resistance_group = {
+	concrete = 16,
+	tree = 3.4,
+	uranium_block = 500,
+	wood = 1.7,
+}
+local cache_radiation_resistance = {}
+local function node_radiation_resistance(node_name)
+	local resistance = cache_radiation_resistance[node_name]
+	if resistance then
+		return resistance
+	end
+	local def = minetest.registered_nodes[node_name]
+	if not def then
+		cache_radiation_resistance[node_name] = 0
+		return 0
+	end
+	resistance = def.radiation_resistance or
+			rad_resistance_node[node_name]
+	if not resistance then
+		resistance = 0
+		for g, v in pairs(def.groups) do
+			if v > 0 and rad_resistance_group[g] then
+				resistance = resistance + rad_resistance_group[g]
+			end
+		end
+	end
+	resistance = math.sqrt(resistance)
+	cache_radiation_resistance[node_name] = resistance
+	return resistance
+end
+
+
+--[[
+Radioactive nodes cause damage to nearby players.  The damage
+effect depends on the intrinsic strength of the radiation source,
+the distance between the source and the player, and the shielding
+effect of the intervening material.  These determine a rate of damage;
+total damage caused is the integral of this over time.
+
+In the absence of effective shielding, for a specific source the
+damage rate varies realistically in inverse proportion to the square
+of the distance.  (Distance is measured to the player's abdomen,
+not to the nominal player position which corresponds to the foot.)
+However, if the player is inside a non-walkable (liquid or gaseous)
+radioactive node, the nominal distance could go to zero, yielding
+infinite damage.  In that case, the player's body is displacing the
+radioactive material, so the effective distance should remain non-zero.
+We therefore apply a lower distance bound of sqrt(0.75), which is
+the maximum distance one can get from the node center within the node.
+
+A radioactive node is identified by being in the "radioactive" group,
+and the group value signifies the strength of the radiation source.
+The group value is the distance from a node at which an unshielded
+player will be damaged by 1 HP/s.  Or, equivalently, it is the square
+root of the damage rate in HP/s that an unshielded player one node
+away will take.
+
+Shielding is assessed by adding the shielding values of all nodes
+between the source node and the player, ignoring the source node itself.
+As in reality, shielding causes exponential attenuation of radiation.
+However, the effect is scaled down relative to real life.  A node with
+radiation resistance value R yields attenuation of sqrt(R) * 0.1 nepers.
+(In real life it would be about R * 0.69 nepers, by the definition
+of the radiation resistance values.)  The sqrt part of this formula
+scales down the differences between shielding types, reflecting the
+game's simplification of making expensive materials such as gold
+readily available in cubes.  The multiplicative factor in the
+formula scales down the difference between shielded and unshielded
+safe distances, avoiding the latter becoming impractically large.
+
+Damage is processed at rates down to 0.25 HP/s, which in the absence of
+shielding is attained at the distance specified by the "radioactive"
+group value.  Computed damage rates below 0.25 HP/s result in no
+damage at all to the player.  This gives the player an opportunity
+to be safe, and limits the range at which source/player interactions
+need to be considered.
+--]]
+local abdomen_offset = 1
+local cache_scaled_shielding = {}
+local rad_dmg_cutoff = 0.25
+
+local function dmg_player(pos, o, strength)
+	local pl_pos = o:getpos()
+	pl_pos.y = pl_pos.y + abdomen_offset
+	local shielding = 0
+	local dist = vector.distance(pos, pl_pos)
+	for ray_pos in technic.trace_node_ray(pos,
+			vector.direction(pos, pl_pos), dist) do
+		local shield_name = minetest.get_node(ray_pos).name
+		shielding = shielding + node_radiation_resistance(shield_name) * 0.1
+	end
+	local dmg = (strength * strength) /
+		(math.max(0.75, dist * dist) * math.exp(shielding))
+	if dmg < rad_dmg_cutoff then return end
+	local dmg_int = math.floor(dmg)
+	-- The closer you are to getting one more damage point,
+	-- the more likely it will be added.
+	if math.random() < dmg - dmg_int then
+		dmg_int = dmg_int + 1
+	end
+	if dmg_int > 0 then
+		o:set_hp(math.max(o:get_hp() - dmg_int, 0))
+	end
+end
+
+local rad_dmg_mult_sqrt = math.sqrt(1 / rad_dmg_cutoff)
+local function dmg_abm(pos, node)
+	local strength = minetest.get_item_group(node.name, "radioactive")
+	local max_dist = strength * rad_dmg_mult_sqrt
+	for _, o in pairs(minetest.get_objects_inside_radius(pos,
+			max_dist + abdomen_offset)) do
+		if o:is_player() then
+			dmg_player(pos, o, strength)
+		end
+	end
+end
+
+
+if minetest.setting_getbool("enable_damage") then
+	minetest.register_abm({
+		nodenames = {"group:radioactive"},
+		interval = 1,
+		chance = 1,
+		action = dmg_abm,
+	})
+end
+
+-- Radioactive materials that can result from destroying a reactor
+local griefing = technic.config:get_bool("enable_corium_griefing")
+
+for _, state in pairs({"flowing", "source"}) do
+	minetest.register_node("technic:corium_"..state, {
+		description = S(state == "source" and "Corium Source" or "Flowing Corium"),
+		drawtype = (state == "source" and "liquid" or "flowingliquid"),
+		[state == "source" and "tiles" or "special_tiles"] = {{
+			name = "technic_corium_"..state.."_animated.png",
+			animation = {
+				type = "vertical_frames",
+				aspect_w = 16,
+				aspect_h = 16,
+				length = 3.0,
+			},
+		}},
+		paramtype = "light",
+		paramtype2 = (state == "flowing" and "flowingliquid" or nil),
+		light_source = (state == "source" and 8 or 5),
+		walkable = false,
+		pointable = false,
+		diggable = false,
+		buildable_to = true,
+		drop = "",
+		drowning = 1,
+		liquidtype = state,
+		liquid_alternative_flowing = "technic:corium_flowing",
+		liquid_alternative_source = "technic:corium_source",
+		liquid_viscosity = LAVA_VISC,
+		liquid_renewable = false,
+		damage_per_second = 6,
+		post_effect_color = {a=192, r=80, g=160, b=80},
+		groups = {
+			liquid = 2,
+			hot = 3,
+			igniter = (griefing and 1 or 0),
+			radioactive = (state == "source" and 16 or 8),
+			not_in_creative_inventory = (state == "flowing" and 1 or nil),
+		},
+	})
+end
+
+if rawget(_G, "bucket") and bucket.register_liquid then
+	bucket.register_liquid(
+		"technic:corium_source",
+		"technic:corium_flowing",
+		"technic:bucket_corium",
+		"technic_bucket_corium.png",
+		"Corium Bucket"
+	)
+end
+
+minetest.register_node("technic:chernobylite_block", {
+        description = S("Chernobylite Block"),
+	tiles = {"technic_chernobylite_block.png"},
+	is_ground_content = true,
+	groups = {cracky=1, radioactive=6, level=2},
+	sounds = default.node_sound_stone_defaults(),
+	light_source = 2,
+})
+
+minetest.register_abm({
+	nodenames = {"group:water"},
+	neighbors = {"technic:corium_source"},
+	interval = 1,
+	chance = 1,
+	action = function(pos, node)
+		minetest.remove_node(pos)
+	end,
+})
+
+minetest.register_abm({
+	nodenames = {"technic:corium_flowing"},
+	neighbors = {"group:water"},
+	interval = 1,
+	chance = 1,
+	action = function(pos, node)
+		minetest.set_node(pos, {name="technic:chernobylite_block"})
+	end,
+})
+
+minetest.register_abm({
+	nodenames = {"technic:corium_flowing"},
+	interval = 5,
+	chance = (griefing and 10 or 1),
+	action = function(pos, node)
+		minetest.set_node(pos, {name="technic:chernobylite_block"})
+	end,
+})
+
+if griefing then
+	minetest.register_abm({
+		nodenames = {"technic:corium_source", "technic:corium_flowing"},
+		interval = 4,
+		chance = 4,
+		action = function(pos, node)
+			for _, offset in ipairs({
+				vector.new(1,0,0),
+				vector.new(-1,0,0),
+				vector.new(0,0,1),
+				vector.new(0,0,-1),
+				vector.new(0,-1,0),
+			}) do
+				if math.random(8) == 1 then
+					minetest.dig_node(vector.add(pos, offset))
+				end
+			end
+		end,
+	})
+end
+