Outdoor Tanks – Potential Release Issues

Vent – for some sites vented to atmosphere

Overflow line – to a pit or sump (difference?) – where does it go?

Tank leaks – are they contained, how well?

Vent

If to atmosphere, is it accounted? How (empirical, measured)?

Accurately monitor releases from the RWST (outages, fuel failure)

Why? Routine airborne releases typically low, may be a significant contributor to total iodine and/or particulate releases

Problems/Issues

Source terms (makeup water) may contain significant amounts of activity (fuel failures, crud burst)

Makeup water – RCS, “cleaned RCS,” refuel cavity, VCT see OE24665

Source terms - Noble Gas, H-3, Iodines, Particulates Use of calculations has resulted in some issues (+5000

uCi of I-131 for 2R15, doubled MP2 releases, “model” uncertainty, important parameters?)

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; where does it go may be important - GPI)

Iodines and Particulates – ???????

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 RWST, small % released, significant error in calc. (subtraction of large # from large #)2. Actual “effluent sampling” – HOW (e.g., OE24665; LLD)? When to sample?

Temp Mod – Special Study – 2R17 & 2R18

“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)

RWST Tank Vent

Effluent Results

2R17 discussed at last year’s workshop 2R18 results to be briefly discussed What did we learn?

Noble Gases Released – 2R18

Waste Tank (CWMT) transfer to RWST- (< 2R17)1st tank (cancelled) – 0.12 Ci 2nd & 3rd tank - 0.004 Ci each

Cavity Water transfer to RWST – (< 2R17) 1st drain - 0.003 Ci

2nd drain - 0.02 Ci Outage Purge – 2.1 Ci (< 2R17) Outage Ventilation – 7.6 Ci (> 2R17)

I-131 Released

Aux. Bldg Ventilation – 1056 uCi (> 2R17) Equipment hatch – 2.4 uCi (< 2R17) RWST (prior to filtration) – 3 uCi (<2R17) RWST (after filtration) – 0 uCi (<2R17) Did not discharge 1 CWMT (reason: chloride issue;

219 uCi) and the 2 others I-131 LLD, but detectable I-132; 2nd cavity transfer: I-131 LLD

Ground level vs mixed release height and now it was monitored

Note: Alloy 600 replacement during 2R18

I-131/I-132 - Released

Waste Tanks and Cavity transferred within 1 day (not like 2R17); not able to differentiate the Iodine releases from them

I-131 & I-132 exhibited different DF’s (present in different ratios in tanks and cavity, able to show differences in DF’s with source terms (tanks vs. cavity)

Tanks had significantly lower DF (similar to 2R17)

Transfer of waste tanks (2 – 100 DF) and initial cavity drain-down (2000 – 10000 DF) can contribute to significant iodine releases

DFs - I-131

Effluent Results – 2R17

Particulates1. Aux. Building Ventilation – 5 uCi2. Equipment hatch – 14 uCi3. RWST (prior to filtration) – 18 uCi4. RWST (after filtration) – 0 uCi (similar to 2R17)

Although RWST has a significant particulate component, iodine likely more limiting (for doses, dependent on fuel failure) (for sites with no Aux Building HEPA, will be a less significant component)

Results - Particulates

Reduction Factors 2R17 2R18Co-58 – 2.4 e+4 1e+6Co-60 – 4.3 e+4 2e+5Nb-95 – 2.0 e+4 2.5e+5Ag-110m 2e+4Sn-124&125 5e+4Sb-125 – 1.3 e+6 1e+6

RWST Vent Releases - Conclusion

RWST vent may be important for I-131 & particulate effluents: Outages (could increase I-131 by factors of 1 to 4 or more & a

ground level release – depends on several variables) 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 - leakage past isolation values and large pH difference, TSP in CTMT sump for LOCA) - existing LOCA assumptions – may be invalid – I-131 source term may be significantly higher than “expected”)

NRC Information Notices 86-60, 90-64 & 91-56 Particulate releases – significant compared to other source

terms - could explain why we had trace particulate contamination in the MP3 yard

Considering MP3 temp mod for 3R12 (next outage is this Fall)

Foundation Drain Sump 3 (ESF)Sampling Timeline For ESF Sump 3

Sample Date Result Date Results pCi/LConfirmation Date

(as applicable)Results pCi/L Result Discussion

1/2/07 1/4/071920, 2140, 2760,

1050*01/08/2007 2440 (AREVA)

CR-07-01375 generated, results were just above or below LLD value of 2000 pCi/L, focus was on likelihood that H3 was introduced from surface runoff.

5/4/07 NA NA    

Generated CR-07-05070 to revise catch basin monitoring procedure to include MP3 outside underdrain foundation sumps, because of GWPI recommendations.

6/6/07 6/6/07 less than 1770 06/18/2007 1070 (AREVA) Follow-up sample to January result was less than the LLD.

10/5/07 10/5/07 12,000 11/28/07 9390 (AREVA)

First attempt at sample protocol in support of procedure under revision. First result indicated potential interferences; sample was submitted to independent lab for confirmation.

11/28/07 11/28/07 34,000    

Analyses of sump refill water confirms groundwater activity, started GWPI report generation. Generated CR-07-11784.

RWST Overflow Line Found H-3 in MP3 foundation drain (great GPI

sampling point(s); in a way, better than wells!) Performed inspection of sump 3 – sampled 2 of

the 3 inputs (third was “dry”) Traced to RWST pit (diluted with rain, H-3: 4e-3

uCi/ml = 4e+6 pCi/liter; Cs-134, Cs-137, Ni-63 – supports RWST vent “carryover” of particulates)

RWST oveflow pipe – H-3, Co-60 and Cs-127 Source – RWST overflow line (RWST H-3: 2e-1

uCi/ml) Not first time – H-3, Cr-51, Co-58,60, Nb-95 and

Cs-137 in 2002

Sump 3 Actions

Short term corrective actionsincreased sampling, find source & minimize impact, determine extent of plume

Long term corrective actionseliminate source, remediation?

OE26024, OE26571 What about MP2?

MP3 Waste Test Tanks

Negative suction tank vents – adequate? Tank leaks (tank, piping, instrumentation) Berm

Conclusion

Outdoor tanks are a “challenge” RWST Vents – airborne RWST Overflow Lines – GPI Tank leaks – GPI