ML20055B381
| ML20055B381 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 06/08/1982 |
| From: | GENERAL PUBLIC UTILITIES CORP. |
| To: | |
| Shared Package | |
| ML20055B379 | List: |
| References | |
| PCI-TR-212, NUDOCS 8207210627 | |
| Download: ML20055B381 (10) | |
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Encicsure i PCI-TR-212 9210-0591 i,
3 June 8, 1982 l
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i INVESTIGATION AND ASSESSMENT OF THE l
8 BETA AND GAMMA RADIATION EXPOSURE OF i
i AUXILIARY OPERATOR "W" 0N MARCH 28, 1979 4
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..JESTIGATIO1 AND ASSESSMENT OF THE BETA AfiD GNP.A RADIATION EXPOSURE OF AUXILIARY OPERATOR "W" ON MARCH 28, 1979 Table of Contents Section Page 1.
Introduction 1
1 2.
Suim:ary 2
1 3.
Findings and Discussion 3
2 4.
Conclusions 4
6 5.
Recomendations 5
6 6.
References 6
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a
Investigation and Assessment of the Beta and Gama Radiation Exposure of Auxiliary Operator "W" on March 28, 1979
- 1.. Introduction As a result of the TMI Dosimetry Group's retrospective review and evaluation of early dosimetry records for individuals who were exposed due to the Unit II accident of March 28, 1979, it was noted that two TLDs had been processed manually and only the reading of the garma (deep) TLD chip was recorded.
Therefore, the possibility was recognized that the individuals may have received beta exposure to the skin of the whole body from radioactive noble gases and particulates that had not been properly evaluated and reported.
Further investigation revealed that only one individual (Auxiliary Operator "W")
had a reportable overexposure to the skin of the whole body.
2.
Sumary The conditions under which Auxiliary Operator "W" received his exposure on March 28, 1979, have been investigated. As a result of the 1st Quarter 1979 Dosimetry Recovery Project,it was determined that Auxiliary Operator "W" had made two entries into the Unit II Auxiliary Building during the evening of March 28, 1979.
His TLD was read; however, only the gamma dose from the deep chip was manually recorded on the hardcopy printout.
During the dose assessment for Auxiliary Operator "T" (Ref. Letter LL2-81-0003, l
January 15,1981) it was determined that exposure in the Auxiliary Building could have resulted from two main sources; highly contaminated liquids in l
pipes and storage tanks, and radioactive noble gases and particulates. Since Auxiliary Operator "W" had made two entries into the Unit II Auxiliary Building within about an hour of Auxiliary Operator "T's" entry, it was highly l
probable that his sources of exposure were very similar to that of Auxiliary Operator "T".
Many individuals.sho egressed the Uni-II Auxiliary Euilding curing :re evening of March 28, 1979, appeared to have radioactive noble gases and particulates entrapped in their clothing and hair.
As noted above, Auxiliary Operator "W's" TLD was read, but only the recorded gamma dose was reported; therefore, the nonpenetrating (beta) dosa that he may have received to the skin of the whole body must be estimated.
Investigations have shown that the nonpenetrating cose estimate can be based on a cecafga,na:a ratio of 3 to 7 for individuals who were known to have entered the Unit II Auxiliary Building during the period of 1300-2400 hours on March 28, 79.
Using the beta / gamma ratio of 7, the calculated nonpenetrating dose represents a reasonable upper limit of the dose to the skin of the whole body. Therefore, Auxiliary Operator "W's" penetrating dose will be assigned on the basis of the TLD deep chip reading and a calculated nonpenetrating dose for the exposed skin.
The resulting doses are 3.17 rad whole body and 25.36 rad to the skin of the whole body for March 28, 1979.
3.
Findinas and Discussion Written radiation survey records are not available for the period 0400-2400 i
March 28, 1979. Therefore, NUREG-0600 was reviewed, discussions / interviews were held with a number of individuals, and selected NRC interviews and Control Room Logs were reviewed to provide the best information as to Auxiliary Operator "W's" activities and the radiation fields that may have existed when he made his entries into the Unit II Auxiliary Building on March 28, 1979.
The following summarizes the available survey data:
(a) At about 1300 on March 28, 1979, the general area exposure rate near the Radwaste Disposal Control Panel (RWDCP) was about 8-10 R/hr (see Page II-3-50, NUREG-0600).
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(b) HPR-?32 readincs verified that exposure rates were about 6-10 R/hr near the RWDCP during the period 1800-2300 on March 28, 1979.
(c) Exposure rates measured during Auxiliary Operator "W's" two entries into the Unit II Auxiliary Building on March 28, 1979, are as follows:
(1) First Entry:
-Entrance to 305' elevation.................. 20 R/hr
-denerai areas of the 328' elevation.....30-100 R/hr
-Core Flood Ni trogen Valves.................. 10 R/hr Total stay time in Auxiliary Building was about 5 to 10 minutes, probably less than 10 minutes.
(.2) Second Entry:
-Past Makeup Tank Area and inside the Switch Gear Rooms on the 305' elevation............ 30 R/hr
-Radwaste Disposal Control Panel............. 10 R/hr
-Mo d el Room................................... 3 R/ h r Total stay time in Auxiliary Building was about 10 minutes, with about 2-3 minutes in the Model Room.
Based on the above data, Auxiliary Operator "W" probably received about 60 to 70 percent of his whole body dose during his first entry into the Auxiliary Building. This finding substantiates the statement in Auxiliary Operator "W's" NRC interview, where he said that he thought that he had received most of his exposure during his first entry.
After he dressed out in coveralls (but did not wear a rainsuit), hood, boots, and a Scott air pack, and wearing his TLD under his coveralls in his shirt pocket, Auxiliary Operator "W" made his first entry into the Unit II Auxiliary Building at about 2100 on March 28, 1979, to pressurize the core flood tanks with nitrogen. He made this entry alone, but he had a Teletector during the entry. When he entered the Auxiliary Building on the 305' elevation
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,a irrecia:sO went un :.ne stairs to the 323' elevation tt me core ficod tank valves that are actually located in the Fuel Handling Building.
Exposure rates on the 328' elevation were as high as 100 R/hr.
It took him about 10 minutes to complete this entry.
His 200 mR self-reading dosimeter (SRD) was off scale when he returned to the Unit II Control Room where the nearest frisker was, and he frisked himself.
The frisker pegged, (RM-14 with HP-210 probe) most probably frcm radioactive noble gases and particulates being entrapped in clothing and hair. He did not shower (decontaminate) prior to making another entry into the Unit II Auxiliary Building.
Auxiliary Operator "W" made another entry into the Auxiliary Building to transfer pre-accident Unit II water from the Unit II Neutralizing Tank WLD-T-8B to Unit I MWHT. Auxiliary Operator "W" entered the Auxiliary Building on the 305' elevation and went to the Radwaste Disposal Control Panel (RWDCP) through the switch gear area to perform the valve line-up for the water transfer.
The second entry into the Unit II Auxiliary Building was made alone at about 2120 on March 28, 1979. The exposure rate was about 10 R/hr at the RWDCP.
The switch gear was de-energized for the Neutralizing Tank pump and the pump would not start. Auxiliary Operator "W" waited for a short while (about 2 - 3 minutes) in the Model Room, where the exposure rate was about 3 R/hr, before the Control Room overrode WDL1311 to start the pump. However, the pump still would not energize, so he checked the breakers, found they were tripped, and then he proceeded out of the Auxiliary Building for the second time that evening. Auxiliary Operator "W" had been in the Auxiliary Building for about 10 minutes on this second trip. His 200 mR SRD was off scale again. Auxiliary Operator "W" went back to the Unit II Control Room to frisk. The frisker pegged again. He then proceeded to Unit I to shower. After his decon efforts he had no residual contamination.
i The concentrations of radioactive noble gases and particulates in the Auxiliary Building were very time dependent because of activities that were taking place in the plant.
Therefore, it is only possible to estimate Auxiliary Operator "W's" nonpenetrating dose based on the TLD Chip 1/ Chip 2 ratios for individuals who were known to have entered the Auxiliary Building during the period of 1300 to 24C0 on March 28, 1979. The average TLC Chip 1/ Chip 2 ratio was about 3:1 while the maximum ratio was about 7:1. The beta / gamma (Chip 1/ Chip 2) ratio of 7 is substantiated by the work of Plato et al; see References 6(a) and 6(.b) and a control TLD located in the Unit II HP Area during the period of March 28 - 31, 1979 (See Attachment).
Based on the 3.17 rad penetrating dose obtained from his deep TLD chip it is possible that Auxiliary Operator "W" may have received a nonpenetrating dose to the skin of the whole body of 9,510 to 22,190 mrad based on a beta /gama ratio of 3 to 7 respectively.
4.
Conclusions Based on the above, it was concluded that Auxiliary Operator "W" was exposed to radioactive noble gases and particulates as well as fixed sources while in the Unit II Auxiliary Building. As a conservative estimate, he received a total (beta plus gama) dose to the skin of the whole body of 25.36 rad during his entries into the Unit II Auxiliary Building on March 28, 1979.
Based upon available infonnation/ records, Auxiliary Operator "W's" occupational dose for the first calendar quarter of 1979 is as follows:
mrad mrad mrad Exposed Total mrad Whole Body Whole Body Skin of Whole Body Dose to Skin Period Gama Neutron Beta of Whole Body 1/1/79 - 1/31/79 25 0
0 25 2/1/79 - 2/15/79 0
35 0
35 2/1/79 - 2/28/79 270 0
0 270 3/1/79 - 3/27/79 390 0
0 390 mrad' mrad mrad Exposed Total mrad Whole Body Whole Body Skin of Whole Body Dose to Skin Period Garca Neutron Beta of Whole Body 3/28/79 - 3/28/79 3,170 0
22,190 25,360 3/29/79 - 3/29/79 15 0
0 15 3/30/79 - 3/30/79 0
0 0
0 3/31/79 - 3/31/79*
0 0
0 0
First Quarter 3,870**
35**
22,190**
26,095
- Secause Auxiliary Operator "W" had exceeded the whole body quarterly limit, he was not on the Island on March 31, 1979.
- This gamma exposure was reported to the NRC by Letter GQLO620, on May 1,1979; however, the beta and neutron doses had not been evaluated at the time of the initial report to the NRC. Therefore, his total whole body dose is 3.905 rad for the 1st Calendar quarter of 1979.
5.
Recommendations It is recommended that the doses in Section 4 above be assigned to the official First Calendar Quarter 1979 Dosimetry Records of Auxiliary Operator "W".
A copy of this report should be submitted to the NRC as required by 10 CFR 20.405.
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References (a) Plato, P. A. ; Hudson, C. G. ; Katznan,0. ; and Sha R. ; " Calibration of Environmental and Personnel Dosimeters by Submersion in and Distant Exposure to Xe-133," Health Physics, Vol. 38, 523-528 (April 1980).
(b) Datley, D. ; Hudson, G. ; and Plato, P. ; " Projected Response of
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Panasonic Cosimeters to Submersion in and Distant Exposure by Xe-133," Health Physics, Vol. 41, 513-525 (September 1981).
(c) Riley, R. J. ; Zanzonico, P. B. ; Masterson, M. E.; St. Germain, J. M. ;
and Laughlin, J. S.; " Evaluation of the Response to Xenon-133 Radiations by Thermoluminescent Dosimeters Used During the Accident at Three Mile Island," Health Physics, Vol. 42, 329-334 (March 1982).
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' '0!ICT COPCUlI.1NIS, 13C.
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19003 215 896 5353 UNIT II HP CONTROL POIhT AREA TLD DATA - 999-99-9948_
Time:
1/1/ - 1/31/79 Badge No:
410073 Dose:
0.01 rem gama M
Time:
2/1 - 2/28/79 Badge No:
410073
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Dose:
0.02 rem gama Time:
3/1 - 3/31/79 Badge No:
410073 Dose:
1.08 rem gama, 7.3 rad beta, beca/ gamma - approximately 6.8 Time:
4/1 - 4/26/79 Badge No; 410073 1
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Dose:
0.000 Attachment
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