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Problem

Problem. Accurately monitor releases from the RWST (for fuel failure conditions) Why?. RA-RA-RA. Record All Releases As Reasonably Achievable. Problems/Issues. RWST (at MP) is vented to atmosphere

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Problem

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  1. Problem • Accurately monitor releases from the RWST (for fuel failure conditions) • Why?

  2. RA-RA-RA • Record • All • Releases • As • Reasonably • Achievable

  3. Problems/Issues • RWST (at MP) is vented to atmosphere • Source terms (makeup water) may contain significant amounts of activity (fuel failures) • Use of calculations has resulted in some issues (+5000 uCi of I-131 for 2R15, uncertainty)

  4. RWST Vent • Contaminated sources (unprocessed pressurizer water, waste water, refuel cavity water, VCT see OE24665) • Source terms (Noble Gas, H-3, Iodines, Particulates)

  5. Release Quantification • Noble gas – easy, just assume it is all released (or you could be less conservative and do an activity balance, i.e.. what’s released = what goes in – what stays in the RWST) • H-3 – release = water lost due to evaporation (we assumed negligible based upon review of another site’s method – also think about comparison to SFP) • Iodines and Particulates – ???????

  6. Quantification – I & Part. • Calculations based upon source term & assumed RF’s (EPRI project NP-1271- Nuclear Power Plant Related Iodine Partition Coefficients) – Rad Engineering gave us #’s ranging from 100 – 3000 • Measurements1. Activity Balance – problems with tank recirculation, potential plateout in RWST2. Actual “effluent sampling” – HOW (e.g., OE24665; LLD)?

  7. Temp Mod – Special Study Capture and analyze the RWST “venting” • Vent pipe mod • Hoses • Moisture separator • Charcoal with pre-HEPA • HEPA • Air sample pumps/filters & sample nozzles (both pre and post filtration)

  8. RWST Tank Vent

  9. Effluent Results – 2R17 • Noble Gases • Iodines • Particulates

  10. Noble Gases • Waste Tank (CWMT) transfer to RWST1st tank - 1.4 Ci 2nd tank - 0.7 Ci • Cavity Water transfer to RWST1st drain - 0.07 Ci2nd drain - 0 Ci • Outage Purge – 13 Ci • Outage Ventilation – 3 Ci

  11. I-131 • Aux. Bldg Ventilation – 621 uCi (2e-2 mrem) • Equipment hatch – 29 uCi (7e-4 mrem) • RWST (prior to filt.) – 116 uCi (3e-3 mrem) • RWST (after filtration) – 5.8 uCi (1e-4 mrem) • Only saved 15% of total by filtration, but this extra would have been ground level and now it was monitored Note: Pressurizer replacement during 2R17

  12. I-131 - Details • Waste Tank (CWMT) transfer to RWST1st - 74.6 uCi (2.3 uCi after filtration) 2nd - 9.8 uCi (0.77 uCi after filtration) • Cavity Water transfer to RWST1st - 29.9 uCi (2.18 uCi after filtration)2nd - 2.1 uCi (0.56 uCi after filtration) • Charcoal filtration varied in effectiveness – moisture issue

  13. Results - Discovery Iodine Reduction Factor (RF) “across tank” • 1.6 for 1st CWMT - pH of 5.69 to 4.31 • 23 for 2nd CWMT - pH of 5.43 to 4.66 • 2770 for 1st Cavity drain – much lesser pH change • 9610 for 2nd Cavity drain - even lesser pH change

  14. Implications- I-131 • Approximate 18% increase in 2R17 effluents (if unfiltered, but at ground level; of which 1/3 was due to cavity water) • Approximate 100% increase in 2R15 effluents (+5000 uCi, for RF = 100; this very likely unconservative based upon this “test”) • Unit 2 has HEPA on Auxiliary Building ventilation (no charcoal) – for plants with charcoal, the % will be significantly higher (factor of 4 increase for ventilation RF of 100, if equipment hatch releases same as ours)

  15. Implications- I-131 (cont’d) • LOCA assumptions – may be invalid – I-131 source term may be significantly higher than “expected” (leakage past isolation values and large pH difference, TSP in CTMT sump for LOCA)

  16. Effluent Results – 2R17 • Particulates1. Aux. Building Ventilation – 0.3 uCi2. Equipment hatch – 3.6 uCi3. RWST (prior to filtration) – 7 uCi4. RWST (after filtration) – 0 uCi • Although RWST a significant component, iodine is much more limiting (for sites with no Aux Building HEPA, will be an insignificant component)

  17. Results - Particulates • Reduction FactorsCo-58 – 2.4 e+4Co-60 – 4.3 e+4Nb-95 – 2.0 e+4Sb-125 – 1.3 e+6

  18. Conclusion RWST vent may be important for I-131 effluents: • Outages (could increase I-131 by factors of 1.2 to 4 or more & a ground level release) • Other events (see OE24665) • LOCA analyses (pH from 7 to 4.6 may cause a significant fraction of the I-131 going over to the RWST to be released) • NRC Information Notices 86-60, 90-64 & 91-56

  19. REMEMBER • Think football/cheerleading – summer football camp is almost here • RA – RA – RA

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