Steam Generator

Question 1

Purpose of Steam Generator

Design d/p across tubes

of tubes

Answer 1

• heat sink for Rx
• generate steam to make electricity
• part of second fission product Barrier
• Barrier between clean water and “hot” water

1600 psig

4444 tubes/SG

Question 2

Flow path through S/G

Answer 2

• in through feed ring (submerged)
• down downcomer annulus
• mixes with moisture separated in M.S.’s
• through tube bundles at bottom
• as rises it boils
• through primary moisture separator’s riser barrel
• through primary M.S.
• through secondary M.S.
• outlet nozzle

Question 3

Normal operating parameters

No load Pstm

100% Pstm

Answer 3

1005 psig

790 psig

Question 4

Describe construction of feed ring

Purpose

Answer 4

Ring with nozzles on top with holes

Keep ring filled with water=>when feed stoped and restarted, no water hammer

Question 5

What is quality of steam exiting S/G?

Answer 5

99.95%

Question 6

What is purpose/functions of integral S/G flow restrictor nozzle?

Answer 6

• minimize pipe whip (reaction force as mass leaves break)
• limit mass and energy release rate into CNMT
• RCS c/d rate limited
• minimize mass flow rate msiv must close against following steam break

Question 7

What parameters ensure “heat sink” is maintained?

Answer 7

15% Ls/g in @ least on S/g

435 gpm total AFW flow

Question 8

What chemicals do we add to S/G’s?

Answer 8

ETA- used for pH control (corrosion control)

Hydrazine- O2 scavenger (corrosion control)

AVT chemicals boil off with steam maintaining chemistry throughout steam system

Sample and monitor for impurities

Question 9

Describe instrumentation of S/G

Answer 9

Level
3 NR detectors (LT-517,518, 519, hot cal)
1 WR detector (LT-501, cold cal)

Press (off steam line)
   3 detectors (PT-514,515,516)

Steam flow (off steam line)
   2 detector (FT-512,513)

Feed flow (off feed line)
   2 detectors (FT-510,511)

Question 10

Steam generator overprotection features

Answer 10

10% steam dumps at 1020 psig
Safeties at 1065 psig( +13+12+13+12)

Question 11

Steam generator tube rupture radiation monitors

Answer 11

MS line RM-71/72/73/74(tuned specifically for N16)
SJAE RM-15/15R(argon)

Question 12

What is swell? What causes swell?

Answer 12

More flow=more turbulence =more head loss=more pressure to maintain flow=higher indicated flow

Rapid up power
Opening of a 10% SDV or SV
Faulted SG

Question 13

What is shrink? What causes shrink?

Answer 13

Less flow=less turbulence =less head loss=less pressure needed= lower indicated level

Turbine trip