Presentation on theme: "Problem Accurately monitor releases from the RWST (for fuel failure conditions) Why?"— Presentation transcript:
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 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)
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 – ???????
Quantification – I & Part. Calculations based upon source term & assumed RF’s (EPRI project NP Nuclear Power Plant Related Iodine Partition Coefficients) – Rad Engineering gave us #’s ranging from 100 – 3000 Measurements 1. Activity Balance – problems with tank recirculation, potential plateout in RWST 2. Actual “effluent sampling” – HOW (e.g., OE24665; LLD)?
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)
Noble Gases Waste Tank (CWMT) transfer to RWST 1 st tank Ci 2 nd tank Ci Cavity Water transfer to RWST 1 st drain Ci 2 nd drain - 0 Ci Outage Purge – 13 Ci Outage Ventilation – 3 Ci
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
I Details Waste Tank (CWMT) transfer to RWST 1 st uCi (2.3 uCi after filtration) 2 nd uCi (0.77 uCi after filtration) Cavity Water transfer to RWST 1 st uCi (2.18 uCi after filtration) 2 nd uCi (0.56 uCi after filtration) Charcoal filtration varied in effectiveness – moisture issue
Results - Discovery Iodine Reduction Factor (RF) “across tank” 1.6 for 1 st CWMT - pH of 5.69 to for 2 nd CWMT - pH of 5.43 to for 1 st Cavity drain – much lesser pH change 9610 for 2 nd Cavity drain - even lesser pH change
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)
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) Implications- I-131 (cont’d)
Effluent Results – 2R17 Particulates 1. Aux. Building Ventilation – 0.3 uCi 2. Equipment hatch – 3.6 uCi 3. RWST (prior to filtration) – 7 uCi 4. 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)
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, &
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