Primary Containment (T23)

Question 1

What are the PCIS Group 1 isolation signals?

What Valves are affected?

Answer 1

x3 Low’s, x3 Hi’s

Low RWL -101”
Low Cond Vac 10” Hg
Low MS Line Press 855 (850) in RUN
Hi MS Line Flow 169 (136) psid
Hi Temp Steam Tunnel 190 (185) °F
Hi Temp Turbine Bldg 196 (187) °F

Valves:
B21-F022A-D (inbd) B21-F028A-D (outbd) (MSIVs)
B21-F016/19 (MSL Drains)
B31-F019/20 (Rx Wtr Sample)

3x Normal MSL rad – isolates small bore pipe
(Setpoint raised upscale @ > 20%)
3x Normal affects B31-F019/20, MVP and SPE

Question 2

What are the PCIS Group 2 isolation signals?

What major systems are affected?

Answer 2

RWL Low + 3”
Drywell High Pressure 1.85 psig
R/B Exh Rad High (R609) 18mr/hr*
R/F Exh Rad High (R611) 18mr/hr*
(R634) 6.9mr/hr*
(R635) 5.7mr/hr *
Drywell Rad High 138 R/hr **
**Isolates D/W & Torus 18” V&P Vlvs ONLY

Major systems:
DW & Torus V & P         (2” CAD & 18”)
DW Floor/Equip Drn
H2O2 Analyzer
TIP Withdraw
FP Monitor
RHR F040/F049
1/2E11-F015

Question 3

What are the PCIS Group 3 isolation signals?

What system/valves are affected?

Answer 3

SELF

Steam Line Press HPCI Lo 134(128) #
Exhaust Diaphragm Press Hi 10 #
Leak Detection
HPCI Area Air Temp 165°F
HPCI Pipe Pen Rm 165°F
Torus Temp 165°F 14(13.5) min TD
Torus ΔT 36°F 14(15) min TD
Flow HPCI Steam Hi 303%
+202 (218)” H20 d/p
-100 H20 d/p

HPCI
E41-F002/3 (Steam Supply)
E41-F041/42 (Torus Suction valves)

Question 4

What are the PCIS Group 4 isolation signals?

What system/valves are affected?

Answer 4

SELF

Steam Line Press RCIC Lo 95 #
Exhaust Diaphragm Press Hi 10 #
Leak Detection
RCIC Area Air Temp 165°F
Torus Temp 165°F 29(28.5) min TD
Torus ΔT 36°F 29(28.5) min TD
Flow RCIC Steam Hi 307%
+143 (199/173)” H20 d/p
-100” H20 d/p

RCIC
E51-F007/8 (Steam Supply)

Question 5

What are the PCIS Group 5 isolation signals?

What system/valves are affected?

Answer 5

RWCU
G31-F001/4

RWL Low Low -35”
RWCU Differential Flow Hi 56 gpm for 42.5 s

Room High Temp 140°F
Pump Room
Hx Room
CUPS Room

Room ΔT
Pump Room 60°F
Hx Room 60°F (45°F)
CUPS Room 60°F (40°F)

G31-F004 ONLY
NRHX Outlet Temp Hi 140°F
SBLC Actuation (from MCR)

Question 6

What are the PCIS Group 6 isolation signals?

What system/valves are affected?

Answer 6

RWL Low + 3”
RPV Pressure >138 psig

RHR in SDC
E11-F008/9 (RHR Shutdown Cooling Suct Vlvs)

Question 7

What is the purpose of primary containment and what exposure limits does it provide for?

Answer 7

Contains radioactive material in a controlled volume and, in conjunction w/ ECCS, prevent exceeding rad exposure limits of 10-CFR-100 for a postulated LOCA (25 Rem WB, 300 Rem thyroid, w/in 2 hrs in exclusion area & entire accident w/in 5 miles)

*Not sure that 10-CFR-100 is the correct document, pretty sure that it is 10-CFR-50.67

Question 8

What are the internal/external pressure limits for the Drywell?

What are the Temperature limits?

What is the T.S. limit for DW temperature?

Answer 8

Internal press – 56 # External press – 2 #

Temp – 340°F (281°F)

T.S./EOP DW Temp ≤ 150°F in Modes 1, 2 and 3

Question 9

Where is the sacrificial shield located? What is its purpose?

Answer 9

Inside the Drywell

“Sacrificial” shield protects portions of DW space from excessive rad exposure during ops

During S/D, sacrificial shield provides shielding from Rx vessel radiation for personnel

Question 10

Where is the biological shield located? What is its purpose?

Answer 10

Outside the Drywell

Concrete serves as primary radiological “biological” shielding for personnel in Rx Bldg

Limits to 2.5 mr/hr

Question 11

What is the min/max water level in the Torus for normal operations?

Answer 11

T.S. 3.6.2.2

Min ≥146”
Max ≤150”

Mode 1 2 & 3
LCO
Torus Water Level shall be ≥ 146 in and ≤ 150 in
Conditions
A. Water Lvl not in limits - Restore to limits in 2 hrs
B. Not Met Mode 3 in 12 & Mode 4 in 36

Question 12

What are the Torus Temperature limits? What modes are they applicable for?

Answer 12

Torus Temp Limitations Mode 1,2,3 & >Rng 7 IRM:

95° F: Enter Abnormal procedures and initiate torus cooling

100°F: Place both loops of torus cooling in service & enter TS LCO

105°F: Suspend all RCIC/HPCI testing, enter TS LCO

110°F: Scram reactor IMMEDIATLEY & enter TS LCO

120°F: Depressurize the reactor vessel to < 200 psig.

Question 13

What is the purpose behind inerting the Drywell with Nitrogen?

Answer 13

Inerting primary containment with N2 lowers the O2 levels in the containment atmosphere so that an EXPLOSIVE mixture is not reached when H2 is produced during LOCA conditions.

Question 14

What are the Leakage Limits?

Answer 14

Pressure Boundary None

Unidentified ≤ 5 gpm

Total ≤ 30 gpm

Unidentified increase within previous 24 hours ≤ 2 gpm

Question 15

What is the difference between the Drywell Equipment Drain Sump and the Drywell Floor Drain sump?

Answer 15

Drywell Equipment Drain Sump (DWEDS) - collects water from identified or known sources (hard piped equipment drains)

Drywell Floor Drain Sump (DWFDS) - collects water from unknown or unidentified sources (floor drains)

Question 16

What is the purpose of the Rx Building/Torus Vacuum breakers? How many of them are there?

Answer 16

2 lines (w/ 2 valves in series) - run from Rx Bldg atmosphere to air space inside Torus – each line provides 100% capacity

First valve (outboard) – self actuating check valve

Second valve (inboard) – air operated butterfly type vacuum breaker (for isolation/testing purposes)

Intended to bleed air from Rx Bldg into Torus

Completely opens w/in 1 second after a 0.5 psid applied across the seat – each line provides 100% capacity

Question 17

What is the purpose of the Drywell/Torus Vacuum breakers? How many of them are there?

Answer 17

12 vacuum relief valves located inside Torus on continuous vent header w/ a direct flow path into DW – total combined capacity of 133%

Intended to return non-condensable gases from Torus to DW

Completely open w/in 1 second after 0.5 psid applied across the seat.

Self-actuating w/ remote controlled air operator for testing

Question 18

What signals cause the purge supply valves (307, 308, 309, and 324) and Drywell Torus 18” vents (318, 319, 320 and 326) to isolate?

Answer 18

High Drywell pressure 1.85psig
Low RPV level +3”
Rx Building Hi Radiation 18 mr/hr
Drywell Hi Radiation 138 R/hr

Question 19

What do the amber lights above the 18” vent valves (307, 308, 309, 318, 319, 320, 324, 326) mean?

Answer 19

Indicate Hi Drywell Radiation at 138 R/hr

Question 20

What are the major Torus water levels of concern?

Answer 20

57.5” (63”) SRV T-Quenchers uncovered

98” (102”) Downcomer Vent Openings Uncovered

110” (115”) HPCI exhaust vent uncovered

146-150” Technical Specification LCO

193” Bottom of Ring Header (Pressure Suppression capability maintained below this level)

215” (197.5”) Torus to Drywell Vac Bkrs covered

285” Torus spray headers covered

Question 21

What are the consequences of a failed Torus to DW vacuum breaker?

Answer 21

FAILED OPEN - Containment pressure can exceed 56 psig on DBA LOCA due to loss of suppression capability.

FAILED CLOSED - Containment pressure can exceed external pressure of 2 psid when DW sprays are placed in service (condensation, vacuum effect).

Question 22

What is the Tech Spec for DW Pressure? Required action and time?

Answer 22

Drywell pressure shall be ≤ 1.75 psig

MODES 1, 2, and 3

A.1 Restore DW pressure to within limit in 1 hour

Question 23

How do the Drywell Drain Sump Timers work?

Answer 23

Sump pump-out timer, Sump fill timer, Level HI-HI

Timer starts on sump pump activation
If pump still running when timer times out, you get “Drywell Floor/Equipment Drains Sump Leak High”

“Fill timer” starts when pump stops. If pump starts prior to timer expiration, same annunciator alarms.

“Drywell Equip/Floor Drains Sump Lvl High-High” indicates a pump start failure or in-leakage is greater than 100 gpm
The second pump auto starts when High-High alarm comes in

140 F, sumps goes into recirc

Question 24

How does the TIP system respond to PCIS isolation?

Answer 24

The majority of the time, the TIP system will not be in use; the probe will be IN SHIELD and the ball valve will be closed

If the probe is inserted past the ball valve and it is necessary to isolate the containment (Group 2 signal), the probe must first be withdrawn before the ball valve can be closed

A backup isolation shear valve, for remote manual operation, is provided to ensure isolation in the event that the probes are jammed in the vessel when isolation is required

Confirm leak is in TIP room to actuate the shear valve.