Pure oxide refractories are generally monocrystaliine in nature and are self bonded __________ bricks are generally used as moderator in nuclear reactors.

Heavy water is used as a moderator in a nuclear reactor. The function of the moderator is

A

to control the energy released in the reactor

B

to absorb neutrons and stop the chain reaction

C

to cool the reactor

D

to slow down the neutrons to thermal energy

Given that, 24 carat gold is pure gold, 18 carat gold is 3/4th of pure gold and 20 carat gold is 5/6th of pure gold, the ratio of the pure gold in 18 carat gold to the pure gold in 20 carat gold is -

A

5 : 8

B

10 : 9

C

8 : 5

D

9 : 10

A first order reaction is to be treated in a series of two mixed reactors. The total volume of the two reactors is minimum, when the reactors are

A

Equal in size

B

Of different sizes

C

Of such size that the ratio of their volumes is

D

None of these

Faster rate of drying of moulded refractories results in high __________ of refractories.

A

Green strength

B

Voids

C

Shrinkage

D

Both B and C

Nuclear fuel generally used in reactors is uranium oxide instead of uranium, because the former has higher

A

Melting point, hence can be subjected to higher temperature

B

Density ; hence core volume for a given power output would be smaller

C

Resistance to effects of irradiation

D

All of the above

A red house is built from red bricks . A blue house is built from blue bricks. A white house is built from white bricks. Then what is a greenhouse made from ?

A

green bricks

B

wood

C

glass

D

steel

The solid brick shown is made of small square shaped bricks of side 1. when the large brick is disassembled into its component small bricks. the total surface area of all the small bricks is how much greater than the surface area of the large brick?

A

32

B

40

C

60

D

72

Where reactor operation is designed with fast neutrons such as in reactors using highly enriched fuel, the moderator used is

A

Heavy water

B

Graphite

C

Carbon dioxide

D

No moderator is needed

Tar bonded dolomite bricks

A

Are stored under controlled temperature & humidity to avoid hydration

B

Are used in outer lining of L.D. converters

C

Have poorer hydration resistance than pitch bonded bricks

D

All of the above

A moderator generally used in nuclear power plants is

A

Graphite

B

Heavy water

C

Concrete

D

Graphite and concrete

Pure oxide refractories are generally monocrystaliine in nature and are self bonded __________ bricks are generally used as moderator in nuclear reactors.

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