ML19220B477
| ML19220B477 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/12/1979 |
| From: | Barrett L Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7904260292 | |
| Download: ML19220B477 (20) | |
Text
.
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APR I 2 im i
met:CRA!iDU!1 FOR:
Distribution t
}
FRO 1:
Lake H. Barrett, Sect, ion Leader, Environnental Evaluation i
Branch, Division of Operating Reactors, OfiRR t
(
SLBJECT:
PRELIMINARY ESTItiATES OF RADI0 ACTIVITY RELEASES FROM THPEE ItILE ISLAtiD I
i Attached is a sumary of available infomation in Bethesda regarding enticates of radioactivity releases from 'Ihree flile Island. We have estimated a total i
Xe-133 release of approxirately 13 million curies and an I-131 release of ap-proxicately 1 A curies from March 28 through April 5.
This estimate was nade by back calculating radioactivity releases using measured offsite TLD dose data, radiciodine air concentratfor.s and concurrent meteoroloaical conditions. As l
nore infomation and time become available, more refineil calculations can be' i
rade.
ii As of midday April 9,1979, the population dose due te noble gases is estimated to be 2400 man-rens with the maximum individual exposure at less than 100 mrem (33 tren).
i (signed)
L. Barrett i
Lake H. Barrett, Section Leader Environrental Evaluation Cranch Division of Operating Reactors l
Office of fluclear Reactor Regulation
Enclosure:
As stated DISTRIBUTI0ti:
Distribution:
Central Files As attached EEB Reading
!!RR Reading (P-428)
L. Barrett D. tiossburo
- R, O 4 2 (o o ff 1 EEB/ DOR EEB/ DOR or,,c.
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DGhd* Pr%3 Rad 113 d e.74 % MECM 02mA k u.s. eowee nasset meeswee oersca : t eve - aos - Fee
Distribution Memorandum on Preliminary Estimates of Radioactivity Releases from Three Mile Island V. Stello B. Grimes R. Vollmer F. Congel G. Knighton L. G. Hulman W. Kreger R. W. Houston D. Davis G. Lainas M. Aycock D. Eisenhut F. Miraglia J. Fairobent L. Battist J. Buchanan
(.,w 1.11
~x
SUMMARY
OF PRELIMINARY RADI0 ACTIVITY RELEASES FROM THREE MILE ISLAND AS OF APRIL 7, 1979 Preliminary rough estimates of Xe-133 and I-131 releases frcm Three Mile Island (TMI) have been made based on reported environmental measurements made with off-site TLDs and radiciodine air samplers using meteorolocical data con-current with the environmental measurement times.
This approach has been used to obtain a rough estimate of releases because accurate in-plant effluent moni-tor information is not available at this time. The ventilation exhaust monitors did not provide accurate readings of absolute quantities of radioactivity re-leases during the accident because of high airborne radioactivity concentra-tions and direct radiation from auxillary building components resulted in in-accurate readings, e.g., off scale.
The most feasible method for rough preliminary estimates of the amount of noble gases releesed during the accident is to back-calculate a curie release based on radiation measurements taken in the environs, the isotopic spectrum of the effluents and actual meteorological conditions. Environmental TLDs have been used to provide the best estimate of the integrated radiation dose at a specific location.
R'ound sur.3y measure ents with portable instrumenta-tion have not been used because the actual measurement reported was for a spe-cific short time period ('10 seconds when the reasurement was taken) which is not a long enough time period to permit the calculation of meteorological dispersion conditions.
Tne isotopic distribution has been assumed to be essentiall; Xe-133 based upon ARs data.
ARMS aircraft spectrun measurements indicated m:s:1; a Xe-133 spec-trur In :ne first days, some Xe-135 was detected bu: leve's were an order of 73 112
. magnitude below Xe-133 and quickly decayed (9 hour1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> half-life) to undetectable levels.
Consequently, we have assumed a single Xe-133 spectrum foi these cal-culations.
Meteorological dispersion factors ( VQ) were calculated for the specific time periods and locations of the exposed TLDs. The weather conditions for these calculations were originally based on information from the haticnal Weather Service. Actual meteorological data from the TMI weather tower has recently been obtained by HMB and has been used with the weather service data in determining the dispersion factors for the TLD locations.
The equations and assumptions used for the calculation of the releases is pro-vided in Table 10.
Table 1 is a summary of the Xe-133 release from TMI as a function of the time the TLDs were exposed.
Tables 2 through 8 are the TLD and meteorological data used to make the estimated release for each time period.
The estimated re-lease for each time period is the aveiage of the release calculated for each of the TLD locations.
Considering the assumptions necessary to permit hand calculations tne release estimates based on each of the TLC readings are fairly consistent.
The total release of Xe-133 through April 5 using this method of estimation is 13 million curies.
Lawrence Livermore LaLoratory (LLL) has also provided a very r:uen estimate" cf :ne releases on April 4 based on ARMS information, wnicr is 'ncecendent of tre TLD c.?. nod used herein.
LLL estimated the most"prctacle re'easf rate as 73~113
. 20 to 50 Ci/sec of Xe-133.
This corresponds to 14 million to 34 million curies of Xe-133 through April 5 which is consistent with the NRC estimate of 13 million.
The iodine 131 releases have also been estimated using a similar method but with measured I-131 concentrations instead of TLD data.
Eight offsite iodine sampler locations have been reported.
The estimated I-131 release through April 3 is 1.4 curies.
The offsite radiciodine concentrations, sampler loca-tions, and meteorological conditions are provided in Table 9.
To date we have not received any useful information from the radiciodine in-plant monitors. The radiciodine samplers should have been continuously samp-ling the effluents from the station vent except for the period from 0100 to 0330 on March 30 when the auxiliary building fans were secured in an attempt to reduce the release rate. When the fans were secured some unsampled build-ing exfiltration took place, however, this was only for a short period. The iodine sampler contains a charcoal cartridge which can be removed and analyzed for radiciodines in a laboratory.
Data from the inplant radiation detector which normally monitors the charcoal cartridge has not been reliable because noble gases also accumulate on the charcoal cartridge resulting in abnormally high readings.
These charcoal cartridges can be counted in a laboratory within a few weeks and accurately predict what the actual I-131 release had been.
No historical information can be established from the effluen-instrumentation for noble gases when the monitors are off scale.
Information such as
,b
4 area radiation monitor readings could be useful in the future for estimating airborne concentrations, however, direct radiation from com;onents will make this approach difficult,if not impossible.
The noble gas release history in Table 1 is generally consistent with various activities that occurred during the post-accident period.
The higher release rate of the 28th and 29th probably correspond to the pumping of the contamina-ted water from the containment sump to the Auxiliary Building tanks which over-flowed onto the Auxiliary Building floor.
The noble gases then evolved from the water as it was exposed to the building air and was then exhausted by the auxiliary building ventilation system. On about 3/29 much of the water that had spilled on the floor had been pumped into tanks which reduced the evolution of gases to the air. The release rate after 3/29 and before 3/31 was reduced possibly because the letdown flow path of primary coolant was to the Reactor Coolant Bleed Holdup tanks and waste gas system.
The increase in release on 3/31 could corrtspond to the establishment of the normal letdown path through the Makeup Tank.
Establishment of normal letdown resulted in several gaseous releases as problems were encountered with leakage of dissolved gases evolving from the makeup tank vent.
Also, during this period the bubble in the reactor vessel was the main concern and efforts were directed toward degasification of the primary system. The method of degasification was through the makeuD tank to the vent gas system and waste gas decay tanks as well as venting the pres-surizer to containment.
During this mode of operation tr.ere were apparent leaks in the vent gas system between the makeup tank and waste gas decay tanks.
Altn.ough little verified information concerning waste gas decay tank pressures QS21.U
. exist at this time, it appears that the waste gas decay tank pressures did not increase as much as was expected, also indicating vent gas system leakage.
The degasification of the primary system through the makeup tank could well have removed much more than 10% of the noble gases from the primary system.
The in-itial core inventory of xenon at 0400 cn 3/28 was 140 million curies.
It is possible when considering the amount of Xe-133 available to be released to the primary coolant, the severe core overheating, the method cf primary system de-gasification and the leaks in the vent gas system between the nakeup tank and waste gas decay tanks that the release of 13 million curies of Xe-133 is feasible.
It is again stated that these quantitative estimates have been based on data reported from the TMI site.
Much of the information was provided verbally from the site and cannot be verified at this time. As rore information becomes available, more accurate estimates can be made.
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TABLE 3 floble Gas Release Estimates Time Period 3/29 (1500 hrs) - 3/31 (1000 hrs)
(43 hr period)
TLD TLD Calculated Release x/g Location Dose (1111es)
(Direction)
(mrem)
(s/m )
(C1 Xe-133) 2.3 SSE 9.3 2 x 10-6 1.0 x 106 6
13 S
1.7 2 x 10-7 1.8 x 10 I
15 flW 2.1 8 x 10-8 5.6 x 10) 15 SE 1.7 1 x 10-7 3.6 x 106 6
2.6 il 2.9 1 x 10-6 6.2 x 10 6
9 SE 1.2 2 x 10-7 1.3 x 10 6
10 EllE 1.3 2 x 10-7 1.4 x 10 Av9 k.2 x 106 q
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TABLE 5 Noble Gas Release Estimates Time Period 4/1 - 4/2 (24 hr. period)
TLD TLD Calculated Location Dose
- x/
Release (Miles)
(Direction)
(mrem)
(s/mg)
(Ci Xe-133) 2.6 303o 1.5 1 x 10-6 3.2 x 105 1.3 2630 1.0 1.
x 10-6 2.1 x 105
- 7. 8 2970 0.6 4.0 x 10-7 3.2 x 105 1.8 200 0.6 6.0 x 10-7 2.1 x 105
- 9. 3 223 0.3 6.0 x 10-8 1.1 x 10 6 Av g.
C3 x 105 h
- Corrected for Background (0.19 mrem / day) i 6, 3
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TABLE 6 Noble Gas Release Estimates Time Period 4/2 - 4/3 TLD TLD Calculated Location Dose
- x/g Release (Miles)
(Direction )
(mrem)
(s/m )
(Ci Xe-133)
-8 6
7.8 297 0.4 2 x 10 4.3 x 10
-7 5
1.3 263 1.2 3 x 10 8.6 x 10
-6 5
1.8 200 1.0 1 x 10 2.1 x 10
-7 6
5.1 272 0.5 5 x 10 1.1 x 10
-7 5
2.4 203 1.1 5 x 10 4.7 x 10
-6 5
2.5 169 2.0 2 x 10 2.1 x 10
~7 6
6.2 178 1.3 2 x 10 1.4 x 10
-7 5
8 181 1.3 3 x 10 9.3 x 10
-7 6
7 225 0.6 1 x 10
- 1. 3 x 10 h
~0 6
9.3 225 0.6 6 x 10 2.1 x 10 31
-7 0
12 184 1.2 1 x 10 2.6 x 10 i
-6 5
1.9 162 4.2 2 x 10 4.5 x 10
~0 5
l.0 151 8.9 5 x 10 3.8 y 10
TABLE 6 (Continued) floble Gas Release Estimates Time Period 4/2 - 4/3 TLD TLD Calculated Location Dose
- y/g Release (flil es )
(Direction )
(mrem)
(s/m )
(Ci Xe-133)
-8 5.3 310 0.4 6.
x 10 1.4 x 106
-7 6
2.6 303 1.1 2.
x 10 1.2 x 10
-6 1.3 252 0.8 2.
x 10 8.6 x 10
~0 5
2.9 270 0.6 1.
x 10 1.2 x 10
-7 5
7.1 262 0.7 7 x 10
- 1. 5 x 10 6
Avg.1.1 x 10 Cort ected for Background (0.19 mrem / day) si
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TABLE 8 floble Gas Release Estimates Time Period 4/4 to 4/5 TLD TLD Calculated Location Dose *
>/Q Release 3
(fliles (Direction )
(mrem)
(s/d )
(Ci Xe-133) a
~7 5
1.0 151 0.73 6 x 10 2.60 x 10
-7 5
1.9 162 0.19 4 x 10 1.02 x 10
~7 5
2.5 169 0.18 1 x 10 3.85 x 10
~0 6.2 178 0.13 7 x 10 3.97 x 10
/
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-8 5
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8.0 181 0.21 6 x 10 7.49 x 10
~0 6
12.0 134 0.26 5 x 10 1.11 x 10 4
l 1.8 200 0.18 1 x 10'0 3.85 x 10
-7 4
2.4 203 0.11 6 x 10 3.92 x 10
-7 5
q
/.0 225 0.26 3 x 10 1.85 x 10
-7 5
9.3 225 0.26 3 > 10 1.85 x 10 f4
-6 4
N 1.3 263 1.11 4 x 10 5.94 x 10 C/I
-6 4
1.3 252 0.53 2 x 10 5.67 x 10
-6 4
2.9 270 0.23 3 x 10 1.64 x 10
-6 4
5.1 272 0.26 2 x 10 2.78 x 10 i
TABLE 8 (Continued)
Noble Gas Release Estimates 1ime Period 4/4 to 4/5 TLD TLD Calculated Location Dose
- x/Q Release 3
(Miles)
(Di rec tion")
(mrem)
(s/m )
(Ci Xe-133)
-6 4
7.1 262 0.41 2
x 10 5.85 x 10
-6 4
2.6 303 0.19 1.0 x 10 4.07 x 10
-7 4
5.3 310 0.14 9.0 x 10 3.33 x 10
-7 5
7.8 297 0.19 2.0 x 10 2.03 x 10 5
Avg.
2.2 x 10
- Corrected for Background (0.19 mrem / day) m.1 bO i
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TABLE 9 (Continued)
Radioiodine Release Estimates
-6 2.6 fl 12.7 2 x 10
),)
-6 1.6 WSW 23.9 3 x 10 1.38
-7 13 S
0.14 2 x 10 0.12 Avg.
1.2 Time Period 3/31-4/3
-5
-3 0.4 fl 0.11 2 x 10 1.4 x 10
-6 2.3 SSE 1.39 2 x 10 0.18
-5
-3 0.4 E
0.27 2 x 10 3.5 x 10
-7 9
SE 0.16 3 x 10 0.14
-2 2.6 fl 0.051 5 x 10-2.6 x 10
-6
-3 1.6 WSW 0.07 2 x 10 9.1 10 h
-7 13 S
0.36 1 x 10 0.93 11 15 f1W 0.024 1 x 10 6.2 x 10-
-7 M
Avg.
0.17 Time Period 3/28-4/3 Cumulative Av9
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