SALEM
SALEM STUDY SYSTEM
Systems > Waste Gas

Waste Gas

⚠️ DRAFT

Waste Gas

Function

The gaseous waste system collects, processes, monitors, and releases gaseous radioactive waste. Sources include: cover gas from the VCT and RCDT, vent gases from various tanks, and containment purge air. Processing includes decay (holdup tanks), filtration (HEPA and charcoal), and dilution. Monitored before release through the plant vent. (UFSAR 11.3)

Gaseous Waste Processing

  • Waste gas decay tanks (GDTs) provide holdup time for radioactive decay before release
  • Gas released through 2WG41 (GDT Vent Control Valve) to the plant vent
  • Plant vent radiation monitor (2R41D) provides automatic protection against unmonitored releases

Radiological Monitoring

  • Process radiation monitors: Monitor liquid and gaseous effluent pathways
  • Area radiation monitors: Monitor dose rates in occupied and restricted areas
  • Containment atmosphere monitors: Monitor containment air for activity
  • Main steam line monitors: Detect primary-to-secondary leakage (SG tube leaks)
  • Effluent monitors: Monitor liquid and gaseous releases at the point of discharge (UFSAR 11.4)
Exam — 2019 Q35
During a 24 GDT release per S2.OP-SO.WG-0011, 2R41 Channel D High Radiation Alarm causes 2WG41 (GDT VENT CONT V) to AUTOMATICALLY close, terminating the release. Other valves open during the release — 24WG34 (GDT STOP TO PLNT), 2WG39 (GDT TO VENT HOR STOP V), 2WG38 (GDT VENT CONTROL VALVE) — do NOT automatically close on 2R41 high radiation. Only 2WG41 receives the automatic closure signal.
Exam — 2022 Q23
2R41D (Plant Vent radiation monitor) in ALARM automatically closes: 2WG41 (GDT Vent Control Valve — terminates waste gas release), 2VC1 and 2VC4 dampers (containment purge), and 2VC5 and 2VC6 dampers (containment pressure relief). Also aligns 2R45 skid to accident sampling loop.

Tech Spec LCOs

Exam — 2023 Q90
Containment pressure relief and ODCM 3.3.9: per Table 3.3-13 Item 3.a, either 2R12A OR 2R41A & D channels is required for containment pressure relief. If only 2R12A fails (power supply failure) and 2R41 channels remain operable, ODCM 3.3.9 is MET — no compensatory actions required to recommence the relief. Trap: Action 37 (two independent samples + verified release rate calculations) only applies if BOTH 2R12A AND 2R41A & D are inoperable. Action 33 (grab samples every 8 hours) applies to the Plant Vent Radiation Monitor, not the containment atmosphere monitor.
JPM — 2023 IP-k
Waste Gas Decay Tank release (S2.OP-SO.WG-0008): latch-and-set sequence on 2WG41 must be performed before commencing release. Max release rate 32 SCFM (Flow Bias <=100%). Terminate release at 10 psig tank pressure: reduce Flow Bias to <0%, close 2WG41-SWT, close 21WG34.
Exam — 2020 Q98
GDT release restrictions per S1.OP-SO.WG-0011:
  • "DO NOT release more than one GDT at a time." (P&L 3.2)
  • "DO NOT transfer Waste Gas from one GDT to another during the GDT Release." (P&L 3.3)
VCT Purge to the plant vent IS allowed during a GDT release — per S1.OP-SO.WG-0005(Q), step 1 of the VCT Purge Radioactive Gaseous Release Form. Trap: waste gas cannot be transferred between units or between GDTs during a release, and only one GDT may be released at a time, but VCT purge is a separate permitted activity.
JPM — 2018 SRO-A4
CRS review of S1.OP-SO.WG-0010 for 13 GDT release: release cannot be authorized due to two errors. (1) Pre-Release Verification in Attachment 1, Section 1.0 not performed. (2) Maximum Allowable Release Rate of 32 SCFM is NOT > 32 SCFM — per NOTE in Step 3.4, tanks with a calculated rate <= 32 SCFM cannot be released. Common trap: finding one error and stopping the review. The examiner cue directs review of the ENTIRE procedure.
JPM — 2019 IP-k
22 GDT release per S2.OP-SO.WG-0009: same latch-and-set sequence as 21 GDT (S2.OP-SO.WG-0008). 22 GDT discharge valves are 22WG31 and 22WG34, pressure instrument is PIS2037. 2WG38 downstream pressure monitored on 2PL8678 — terminate if >8.0 psig. Terminate release when tank pressure reaches 10 psig. MET data recorded during release: Wind Speed 5.8 MPH at El 33 ft, Wind Direction 290 degrees. Calculate average release rate every 10 minutes on Attachment 3.

Physical Connections to Liquid Waste System

Exam — 2018 Q38
Of the Radioactive Liquid Waste System tanks, ONLY the RCDT has a physical connection to the Waste Gas Compressor Header. Other liquid waste tanks (WHUTs, Chemical Drain Tank, Auxiliary Building Sump Tank) do not connect to the waste gas header.

Connections