Systems Exam 3 - Post Accident Instrumentation

Question 1

Post Accident Instrumentation Design Basis Accidents: (3)

Answer 1

1. LOCA
2. Main Steam/Feed Line Break
3. S/G Tube Rupture

Question 2

Type A Variables permit the Control Room operating staff to…

Answer 2

→perform the diagnosis specified in the ERGs
→take the specified pre-planned manually controlled actions, for which no automatic control is provided, that are required for safety systems to accomplish their safety function in order to recover from the DBA, and
→reach and maintain a safe shutdown condition

Note: all of the Type A variables are required by the accident monitoring Tech Spec. The other variables may be required by other specifications, but not specifically for accident monitoring

Question 3

How is Post Accident Instrumentation labelled?

Answer 3

→all Category 1 (RG 1.97) instruments have black labels with white lettering, but not all Category 1 instruments are required by TS 3.3.3 (Modes 1-3)
→in other words, all PAM instrumentation (TS 3.3.3) has black labels with white lettering and are Category 1
→there are additional instruments that are category 1 and have a black label with white lettering

Question 4

List Type A Post Accident Instrumentation (14 items) and review others.

Answer 4

Question 5

Adverse Containment Values

Answer 5

→containment pressure >5 psig, or
→containment radiation >10^5 R/hr, or
→integrated containment radiation dose >10^6 rads (as determined by plant staff)
→Once declared, operators must continue using ADVERSE CONTAINMENT parameters unless integrated radiation dose is verified to be less than 10^6 rads.

Question 6

Post Accident Instrumentation Critical Safety Functions

Answer 6

→subcriticality (reactivity control)
→core cooling
→heat sink
→P - RCS integrity
→Z - containment integrity
→inventory (RCS)

Question 7

Wide Range Gas Monitor (WRGM)

Answer 7

→provides a means to detect significant releases, determine release assessment, and provide long term surveillance for the plant vent stacks
→2 sample flow paths: high flow (low radiation range) and low flow (mid/high radiation range)
→normal, continuous operation is with low range path in service and mid/high range path shut down
→3 detectors with each having a six-decade range (overlap between ranges)
→high radiation signal from the WRGM closes HCV-014 Gaseous Waste Release Valve

Question 8

Six Instrumentation Subsystems of Post Accident Monitoring

Answer 8

Systems designed specifically for accident conditions.

→WRGM for plant vent stack
→MSL monitor (not SG leak rate monitor)
→Containment High Range Radiation monitor (HRRM)
→Containment Pressure WR and NR
→Containment water level (recirc sump level)
→Containment air monitoring (hydrogen concentration)

Question 9

ODCM Section 3.3.3.5 - Radioactive Gaseous Effluent Control

Answer 9

→specifies requirements for Radioactive Gaseous Effluent Monitoring I & C
→WRGM flow rate and sample points
→if WRGM is OOS, flow rate is estimated every 4 hrs OR sample every 24 hrs, depending on which aspect of WRGM is OOS

Question 10

Tech Spec 5.5.4 Administrative Requirement for Control of Radioactive Effluents

Answer 10

→ALARA to the public
→monitor releases

Question 11

Tech Spec 3.3.2 ESF Instrumentation

Answer 11

→containment pressure instruments operable
→Modes 1-3
→trip or bypass in 72 hrs or Mode 3 in 78 hrs, Mode 4 in 84 hrs

Question 12

Tech Spec 3.3.3 PAM Instrumentation

Answer 12

→Modes 1-3
→PAM instruments must be operable