Reactor Accident Including Radiation Hazard

Question 1

Genuine APD alarms could be the initial indication of a problem with the reactor plant and would result in ?

Answer 1

Adopting emergency stations.

Don EBS throughout the sub

Adopt containment state 1

No eating or drinking in sub

Returning to safe depth

Stopping vents

Question 2

How many fission product alarms are there and where are they ?

What do they do ?

Answer 2

4 and there are 2 on each of the port and stbd loops of the primary system.

They monitor for fission products in the primary fluid there should be NONE.

Question 3

In the event of a fission products alarm which would sound in the man room what would happen ?

Answer 3

Checks would be conducted to verify the alarm.

If genuine the following would occur:
- reactor full scram
-full radiation surveys
-secondary containment secured (if sub is < 12 miles from land)

Question 4

What is the core damage gamma monitoring warning there for ?

Answer 4

It monitors gamma radiation levels in the HPDHR hard tank.

Question 5

If the core damage gamma monitor alarms it provides ?

Answer 5

Guidance to command on when they may have to abandon ship.

Guidance to reactor plant operators on how they must operate plant.

Question 6

Radiation surveys are carried out by who using what and what do they do when they get their readings ? And what do they put in place to warn personnel ?

Answer 6

Conducted by medical staff and they conduct the surveys using hand held equipment. They will post signs in areas where stay times are limited and will report their findings to command.

Question 7

When do medical staff conduct radiation surveys ?

Answer 7

When there are any indications which suggest a possible radiation hazard is present.

Or regularly conducted when the reactor is critical.

Question 8

Primary coolant sampling is conducted regularly and checks for ?

Used as a method of checking ?

Answer 8

Water chemistry (reduce corrosion)

Radio chemistry ( changes in radioactivity levels)

Used as a method of checking other alarms are genuine and whether reactor damage has occurred.

Question 9

If any radiation alarms are proven genuine what happens ?

Answer 9

The reactor is full scrammed

Containment state 1 is adopted

Secondary containment will be secured if the submarine is < 12 miles from land

Question 10

When is containment state 1 adopted ?

Answer 10

When taking primary samples and as required by EOP 84

Question 11

Containment state one is achieved by ?

Who do you report to once it’s achieved ?

Answer 11

Shutting all RSC tunnel doors and activating the interlocks (prevent both doors fwd or aft being open at same time) this is managed by the MR and done by ME dept personnel. Reported to command when completed.

Question 12

The primary containment boundary is ?

Answer 12

Sub hull surrounding the RC, RSC and tunnel.

Blkhds 64 and 74

The RSC airlock structures and doors

Systems that penetrate the boundary above up to the containment vvs.

Question 13

Primary containment is secured how ?

Answer 13

Automatically by the containment automatic isolation system (CAIS)

Remotely by MR watchkeepers using the containment manual initiation switch.

Question 14

Function of CAIS is to ?

Answer 14

Monitor RC pressure and MUD vessel pressure

Automatically initiate containment if the channels trip

Provide the man room team with the ability to remote/manually operate containment vvs via push buttons

Question 15

Systems fitted with automatic containment vvs are ?

Answer 15

Main steam.
Trim, bilge and ballast
APD
CAMS
chilled water
Ventilation
Steam drains
Feed transfer
EBS
AV&B

Question 16

Secondary containment boundary is ?

Answer 16

Minimum of pressure hull enclosed by 26 and 88 DCBs.

Maximum is the entire pressure hull.

Question 17

Who controls secondary containment and who is it reported to once it’s achieved ?

Answer 17

Man room team control it and it’s reported to command upon successful completion.

Question 18

What is ultimate containment defined as and when would it be used ?

Answer 18

The isolation of all vvs which can be shut to create a containment boundary. This includes safety systems once they are no longer needed.

If possible in a reactor accident ultimate containment is to be secured before evacuating the submarine.

Question 19

The role of the radiation monitors is to monitor sub for radiation hazards and :

Answer 19

Brief command

Ensure personnel are exposed to minimum radiation when carrying out work.

Set stay times for work which is required.

Question 20

Evacuating the subs crew at sea is done in accordance with EOP 89 abandon ship as follows :

Answer 20

Muster at the escape compartment

Dress in escape suits

Release the fwd and aft indicator buoys

Fin lighting to be switched on

Under direction of the OOW move to the casing

At this point there may be support vessels to be transferred to or personnel may be advised to man life rafts and move away from sub.

Question 21

In the event of a genuine radiation hazard prior to evacuating the submarine personnel will be moved to the onboard shelter stations which are located :

Answer 21

Fwd and aft ends of the sub (to try and place as much distance and shielding between them and reactor)

Non essential personnel will have been evacuated from the sub before this.

Question 22

Why do reactor accident boxes exist ?

Answer 22

They Provide essential equipment required to facilitate the operations required to make the plant and sub as safe as possible before evacuating in the event of a reactor accident.

Question 23

In harbour when is the reactor to be shutdown ?

Answer 23

In harbour if any indication occurs which suggests a radiation hazards or reactor accident may have or might occur.

Question 24

Potential hazards associated with a reactor accident are ?

Answer 24

Personnel contamination onboard

Personnel contamination in the vicinity of sub

Airborne contamination external to sub

Water contamination external to sub

Longer term contamination issues (of land and rivers)

Question 25

Shore support groups for reactor accidents ?

Answer 25

Nuclear accident head quarters

Group support building

Rhu offsite centre