in both locked and unlocked flavors. All of the chests work with the
pneumatic tubes of the pipeworks mod.
+radioactivity
+-------------
+
+The technic mod adds radioactivity to the game, as a hazard that can
+harm player characters. Certain substances in the game are radioactive,
+and when placed as blocks in the game world will damage nearby players.
+Conversely, some substances attenuate radiation, and so can be used
+for shielding. The radioactivity system is based on reality, but is
+not an attempt at serious simulation: like the rest of the game, it has
+many simplifications and deliberate deviations from reality in the name
+of game balance.
+
+In real life radiological hazards can be roughly divided into three
+categories based on the time scale over which they act: prompt radiation
+damage (such as radiation burns) that takes effect immediately; radiation
+poisoning that becomes visible in hours and lasts weeks; and cumulative
+effects such as increased cancer risk that operate over decades.
+The game's version of radioactivity causes only prompt damage, not
+any delayed effects. Damage comes in the abstracted form of removing
+the player's hit points, and is immediately visible to the player.
+As with all other kinds of damage in the game, the player can restore
+the hit points by eating food items. High-nutrition foods, such as the
+pie baskets supplied by the bushes\_classic mod, are a useful tool in
+dealing with radiological hazards.
+
+Only a small range of items in the game are radioactive. From the technic
+mod, the only radioactive items are uranium ore, refined uranium blocks,
+nuclear reactor cores (when operating), and the materials released when
+a nuclear reactor melts down. Other mods can plug into the technic
+system to make their own block types radioactive. Radioactive items
+are harmless when held in inventories. They only cause radiation damage
+when placed as blocks in the game world.
+
+The rate at which damage is caused by a radioactive block depends on the
+distance between the source and the player. Distance matters because the
+damaging radiation is emitted equally in all directions by the source,
+so with distance it spreads out, so less of it will strike a target
+of any specific size. The amount of radiation absorbed by a target
+thus varies in proportion to the inverse square of the distance from
+the source. The game imitates this aspect of real-life radioactivity,
+but with some simplifications. While in real life the inverse square law
+is only really valid for sources and targets that are small relative to
+the distance between them, in the game it is applied even when the source
+and target are large and close together. Specifically, the distance is
+measured from the center of the radioactive block to the abdomen of the
+player character. For extremely close encounters, such as where the
+player swims in a radioactive liquid, there is an enforced lower limit
+on the effective distance.
+
+Different types of radioactive block emit different amounts of radiation.
+The least radioactive of the radioactive block types is uranium ore,
+which causes 0.25 HP/s damage to a player 1 m away. A block of refined
+but unenriched uranium, as an example, is nine times as radioactive,
+and so will cause 2.25 HP/s damage to a player 1 m away. By the inverse
+square law, the damage caused by that uranium block reduces by a factor
+of four at twice the distance, that is to 0.5625 HP/s at a distance of 2
+m, or by a factor of nine at three times the distance, that is to 0.25
+HP/s at a distance of 3 m. Other radioactive block types are far more
+radioactive than these: the most radioactive of all, the result of a
+nuclear reactor melting down, is 1024 times as radioactive as uranium ore.
+
+Uranium blocks are radioactive to varying degrees depending on their
+isotopic composition. An isotope being fissile, and thus good as
+reactor fuel, is essentially uncorrelated with it being radioactive.
+The fissile U-235 is about six times as radioactive than the non-fissile
+U-238 that makes up the bulk of natural uranium, so one might expect that
+enriching from 0.7% fissile to 3.5% fissile (or depleting to 0.0%) would
+only change the radioactivity of uranium by a few percent. But actually
+the radioactivity of enriched uranium is dominated by the non-fissile
+U-234, which makes up only about 50 parts per million of natural uranium
+but is about 19000 times more radioactive than U-238. The radioactivity
+of natural uranium comes just about half from U-238 and half from U-234,
+and the uranium gets enriched in U-234 along with the U-235. This makes
+3.5%-fissile uranium about three times as radioactive as natural uranium,
+and 0.0%-fissile uranium about half as radioactive as natural uranium.
+
+Radiation is attenuated by the shielding effect of material along the
+path between the radioactive block and the player. In general, only
+blocks of homogeneous material contribute to the shielding effect: for
+example, a block of solid metal has a shielding effect, but a machine
+does not, even though the machine's ingredients include a metal case.
+The shielding effect of each block type is based on the real-life
+resistance of the material to ionising radiation, but for game balance
+the effectiveness of shielding is scaled down from real life, more so
+for stronger shield materials than for weaker ones. Also, whereas in
+real life materials have different shielding effects against different
+types of radiation, the game only has one type of damaging radiation,
+and so only one set of shielding values.
+
+Almost any solid or liquid homogeneous material has some shielding value.
+At the low end of the scale, 5 meters of wooden planks nearly halves
+radiation, though in that case the planks probably contribute more
+to safety by forcing the player to stay 5 m further away from the
+source than by actual attenuation. Dirt halves radiation in 2.4 m,
+and stone in 1.7 m. When a shield must be deliberately constructed,
+the preferred materials are metals, the denser the better. Iron and
+steel halve radiation in 1.1 m, copper in 1.0 m, and silver in 0.95 m.
+Lead would halve in 0.69 m if it were in the game, but it's not, which
+poses a bit of a problem due to the drawbacks of the three materials in
+the game that are better shielding than silver. Gold halves radiation
+in 0.53 m (factor of 3.7 per meter), but is a bit scarce to use for
+this purpose. Uranium halves radiation in 0.31 m (factor of 9.4 per
+meter), but is itself radioactive. The very best shielding in the game
+is nyancat material (nyancats and their rainbow blocks), which halves
+radiation in 0.22 m (factor of 24 per meter), but is extremely scarce.
+
+If the theoretical radiation damage from a particular source is
+sufficiently small, due to distance and shielding, then no damage at all
+will actually occur. This means that for any particular radiation source
+and shielding arrangement there is a safe distance to which a player can
+approach without harm. The safe distance is where the radiation damage
+would theoretically be 0.25 HP/s. This damage threshold is applied
+separately for each radiation source, so to be safe in a multi-source
+situation it is only necessary to be safe from each source individually.
+
+The best way to use uranium as shielding is in a two-layer structure,
+of uranium and some non-radioactive material. The uranium layer should
+be nearer to the primary radiation source and the non-radioactive layer
+nearer to the player. The uranium provides a great deal of shielding
+against the primary source, and the other material shields against
+the uranium layer. Due to the damage threshold mechanism, a meter of
+dirt is sufficient to shield fully against a layer of fully-depleted
+(0.0%-fissile) uranium. Obviously this is only worthwhile when the
+primary radiation source is more radioactive than a uranium block.
+
+When constructing permanent radiation shielding, it is necessary to
+pay attention to the geometry of the structure, and particularly to any
+holes that have to be made in the shielding, for example to accommodate
+power cables. Any hole that is aligned with the radiation source makes a
+"shine path" through which a player may be irradiated when also aligned.
+Shine paths can be avoided by using bent paths for cables, passing
+through unaligned holes in multiple shield layers. If the desired
+shielding effect depends on multiple layers, a hole in one layer still
+produces a partial shine path, along which the shielding is reduced,
+so the positioning of holes in each layer must still be considered.
+Tricky shine paths can also be addressed by just keeping players out of
+the dangerous area.
+
electrical power
----------------
* sonic screwdriver
* liquid cans
* wrench
-* radioactivity
* frames
* templates
projects / zefram / minetest / technic.git / commitdiff