Sodium Safety: Action and Reaction

1979 film, with transcript

Catalog description: A liquid metal sodium safety film made as part of the Clinch River Breeder Reactor Program. This is for training operators of sodium-cooled nuclear reactors.

This is film 7479944 in our catalog.

Show transcript
00:30 The fast flux test facility, a test reactor operating at high core temperatures.
00:47 At the FFTF, sodium is used as a coolant to carry reactor heat.
00:51 There are several reasons sodium has been selected.
00:55 One is that it doesn't slow down the fast neutrons in the fission process as much as
00:58 in water-cooled reactors. Another is that sodium has a high boiling point, enabling it to be used
01:05 at essentially atmospheric pressure. In the event of a leak then, the sodium would not be driven out
01:10 as it would in a pressurized reactor. The high temperature at which sodium can be operated will
01:16 result in efficient electricity generation in future liquid metal-cooled reactors. Additionally,
01:22 sodium has excellent heat transfer properties, which would allow the use of a more compact
01:27 reactor core. As you know, there are some potential hazards associated with sodium.
01:33 Your awareness of these hazards is an important part of the assurance that there will be no
01:38 incidents. One concern is the possibility of radioactive contamination. Contamination and
01:45 activation of the sodium can result from the high neutron density within the reactor itself.
01:50 Because of this condition in the reactor, the contaminated sodium will be limited to the
01:54 primary loop, only the sodium's heat will be transferred. This is done by an intermediate
02:00 heat exchanger to a secondary loop of sodium which is not radioactive. After passing through
02:05 the secondary loop, the heat will be released to the atmosphere through these heat exchangers.
02:14 Sodium was in solid form when it arrived in tank cars at FFTF. In this form, it was not
02:19 radioactive. Later it was melted in the tank cars through heating, then transferred to the loops.
02:27 Warning signs and barriers are placed to indicate the location of sodium in the FFTF.
02:32 Be sure to observe and obey these signs. And before you enter any area marked as restricted,
02:38 be sure you are authorized to enter. If you are in doubt, check with the control room first.
02:44 Normal operating temperatures in the FFTF range between 400 and 1000 degrees Fahrenheit.
02:51 Since sodium can spontaneously ignite in air at temperatures as low as 238 degrees Fahrenheit,
02:57 we have designed several features into the plant to moderate the effects of a sodium fire.
03:02 For example, pressure in the system itself is so low, sodium leaks would usually be very small.
03:09 small. Primary sodium systems will be in steel-lined cells which are inerted with nitrogen. Because
03:16 it normally won't contact an oxygen atmosphere, any leakage of primary sodium would not ignite.
03:22 It would flow to the floor and solidify, where it could be easily cleaned up. Secondary sodium
03:28 systems will be in cells which can be flooded with nitrogen to extinguish sodium fires.
03:39 Here at a test site near the 300 area, 20 pounds of sodium is heated to its ignition point.
03:50 The resulting fire is relatively low-lying and gives off little adjacent heat.
04:00 A gasoline fire, by comparison, burns much hotter, sending flames several feet into the air.
04:06 Although a sodium fire appears tame, it cannot be extinguished in the usual way.
04:13 Here's why.
04:14 When sodium combines with water, it forms sodium hydroxide and hydrogen.
04:19 The hydrogen is ignited by the heat of the burning sodium.
04:23 So, rather than extinguishing it, water would feed the flames,
04:26 causing a more serious fire, and under certain conditions, explosions can result.
04:36 Water, then, cannot be used to fight a sodium fire.
04:42 Carbon dioxide extinguishers are also ineffective because if dry ice, which normally forms on
04:48 the nozzle, drops in the sodium, an explosion results.
04:54 Therefore, neither water-filled nor CO2 extinguishers should be found near a sodium system.
05:01 liquid metal fires at FFTF will be fought with nitrogen or NACs. NACs is a fluidized
05:08 form of sodium carbonate. This compound will not interact with sodium, so it is an effective
05:14 extinguishing for sodium fires. NACs extinguishers have a star marking and are yellow. They are
05:21 also labeled NACs. When NACs is sprayed over a sodium fire, it breaks the fire's chain
05:28 It breaks the fire's chain reaction by removing one of the vital links, oxygen.
05:34 As you see, a small sodium fire is easily extinguished by coating the surface with NACs.
05:44 After the sodium is allowed to cool, it solidifies and can then be removed.
05:53 This special gear is an added protection for personnel working in an area where there is
05:57 a sodium leak potential. It includes protective clothing, a hard hat with face shield, and
06:05 spats to protect the shoes. Although the risk of a sodium leak or fire is minimal, there
06:12 is still the potential that such an incident could occur. With your help, however, we can
06:16 be prepared for such an incident and reduce the consequences. In the event of a sodium
06:22 fire, you should inform the control room and other personnel so that the area can be evacuated
06:27 immediately. Operations and maintenance personnel at FFTF are trained to respond in emergency
06:33 situations and fight any fire until the fire department arrives.
06:39 Another factor to consider is personal contact with sodium. Liquid sodium contact with your
06:44 skin poses two hazards. First, since your body is largely water, the sodium will interact
06:51 resulting in a caustic or chemical burn.
06:56 Second, because most sodium in FFTF will be above 300 degrees Fahrenheit, you could receive
07:02 a high temperature burn similar to the kind you would get from hot solder.
07:08 If liquid sodium comes into contact with your skin, you can reduce injury by following these
07:13 simple steps.
07:14 Brush the sodium off.
07:17 Immediately remove all clothing and get under a safety shower.
07:21 stay under the shower for at least 15 minutes. This will allow the remaining sodium to be
07:27 fully reacted with the shower water rather than with your skin. The reason you must remove
07:33 all clothing prior to entering the safety shower is to prevent any sodium which might
07:37 be trapped in the folds of the clothing or in the pockets from interacting with the water
07:42 in the shower. As you saw earlier the interaction of sodium with water could cause an explosion
07:48 leading to further injury.
07:50 In a sodium fire the white smoke produced is made up of sodium oxide.
07:55 It is very acrid and unpleasant.
07:58 But more important, this smoke can interact with the moisture in your lungs,
08:02 your eyes, or even with perspiration on your skin.
08:07 This interaction produces sodium hydroxide and again
08:11 this can result in a caustic burn.
08:14 If a sodium fire occurs,
08:16 Avoid contact or inhalation of the smoke.
08:21 As we have shown any contact with sodium, no matter how minor,
08:25 can produce caustic burns.
08:28 After washing the sodium off, go to first aid immediately.
08:32 Do not ignore the sodium contact because the sodium hydroxide burn will continue
08:37 to grow.
08:38 This effect can easily be counteracted by treatment at first aid.
08:43 We have had extensive experience in handling sodium.
08:46 at the high temperature sodium facility in the 300 area,
08:50 in the 200 area, and at EBR 2 in Idaho Falls.
08:55 We also have information on dealing effectively with sodium fires.
09:00 We're pleased to report there have been no major leaks or serious injuries.
09:04 This is a record we need your help in maintaining.
09:08 The actions you take in the event of a sodium leak or fire are simple and
09:11 effective.
09:13 With your help We will all continue to work in a safe and healthy environment at FFTF.