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

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Presentation on theme: "Problem Accurately monitor releases from the RWST (for fuel failure conditions) Why?"— Presentation transcript:

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


3 RA-RA-RA Record All Releases As Reasonably Achievable

4 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)

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

6 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 – ???????

7 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 Measurements 1. Activity Balance – problems with tank recirculation, potential plateout in RWST 2. Actual “effluent sampling” – HOW (e.g., OE24665; LLD)?

8 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)

9 RWST Tank Vent


11 Effluent Results – 2R17 Noble Gases Iodines Particulates

12 Noble Gases Waste Tank (CWMT) transfer to RWST 1 st tank - 1.4 Ci 2 nd tank - 0.7 Ci Cavity Water transfer to RWST 1 st drain - 0.07 Ci 2 nd drain - 0 Ci Outage Purge – 13 Ci Outage Ventilation – 3 Ci

13 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

14 I-131 - Details Waste Tank (CWMT) transfer to RWST 1 st - 74.6 uCi (2.3 uCi after filtration) 2 nd - 9.8 uCi (0.77 uCi after filtration) Cavity Water transfer to RWST 1 st - 29.9 uCi (2.18 uCi after filtration) 2 nd - 2.1 uCi (0.56 uCi after filtration) Charcoal filtration varied in effectiveness – moisture issue

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

16 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)

17 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)

18 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)

19 Results - Particulates Reduction Factors Co-58 – 2.4 e+4 Co-60 – 4.3 e+4 Nb-95 – 2.0 e+4 Sb-125 – 1.3 e+6

20 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

21 REMEMBER Think football/cheerleading – summer football camp is almost here RA – RA – RA

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