ML19322C455
| ML19322C455 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 06/26/1979 |
| From: | Shuping R HEALTH & HUMAN SERVICES, DEPT. OF, U.S. PUBLIC HEALTH |
| To: | HEALTH & HUMAN SERVICES, DEPT. OF, U.S. PUBLIC HEALTH |
| References | |
| TASK-TF, TASK-TMR NUDOCS 8001170627 | |
| Download: ML19322C455 (3) | |
Text
MEMORANDUM
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runLIC 11F,ALTH sF,RVICE pg 7/g j TOOD AND DRUC ADhe:NIsTRATION
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DATc: June 26,1979 To
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ruoM :Mcdical Radiation Physicist Radiologic Imaging Section, MPB, DEP, BRII sunJrar:TMI Photographic Film Dosimetry Project After the Three Mile Island (TMl) incident, the BRII contacted the Eastman Kodak Company regarding an appropriate photographic film for retrospective dosimetry of the 3MI incident. Kodak recommended the use of Kodacolor 400 film in 35 mm format and offered the company's assistanec in processing any films obtained and in interpretation of results.
Our first action was to visit shops and stores in the TMI vicinity on May 2 and 8 and scarch for Kodacolor 400 film which was present in shops and stores during the first 3 days of the incident.
Six film samples per site were obtained from Elizabethtown, Manchester, Steelton and New Cumberland, PA and from a discount store 2.b miles cast of Middletown, PA.
Other towns and villages (including Middletown, Royalton, Ilighspire, and Goldsboro) were visited,but no appropriate film was found. Either the proper film was placed in the store after the critical 3 day period or no Kodacolor 400 film was stocked.
For reference, samples having similar expiration dates as those collected in Pennsylvania were obtained on May 8 in Rockville and Frederich, MD.
To provide calibrations group (s of films were exposed to x radiation and 3
Xenon 133 gas in an 8 m tent, 2n geometry).
All films were taken by automobile te Rochester, NY on May 8 and processed by Eastman Kodak in.two batches (May 0 and l\\iay 17).
Eastman Kodak provided control strips for cach batch of film obtained in Maryland or Pennsylvania. These controls were being held in the Eastman Kodak fihn vaults at 0 F and were used to provide information on the cxtent of thermal and radiation fogging undergone by the films from Pennystvania and Maryland.
Results The sensitivity of the Kodacolor 400 (CG-135) film to Xenon gas exposure is.05 increase in optical density per 10.mR of exposure to the film cassette. CG 135 *s 35 mm film in a metal cassette. The sensitivity of this film to x ray)is an 0.1 increas in optical density per 10 mR of x radiation (5.05 mm IIVL,100 kVep.
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.r Pftms obtained in Maryland had, on the average, the same from Rockville having the same batch number as the sampic obtained from New Cumberland had a higher fog level than the New Cumberland sampic, None of the fog Icycis observed on the films were judged to be larger than expected from normal aging of the product.
For the Pennsylvania sampics, all fog IcVels except the Middletown sampic were.02 OD or less above the 0 F reference for that batch. The Middletown sample fog IcVel was.025 above the 0 F reference.
If a roll of film is irradiated by a directional source of x radiation, a cyclic density pattern will be goduced on the strip of film. One of G of the Middletown sampics possibly had such a pattern. This pattern and the density increase of 0.025 would correspond to 5 mR of x-or gamma-ray exposure to Xenon 133.
Ilowever, it is possibic for physical effects induced by winding the film on the spool to cause a cyclical pattern such as was seen on the Middletown film.'
Films exposed to Xenon 133 gas in a tent (2n geometry) exhibited a ' cyclical pattern with a sharp spike supcrimposed on the pattern (Soc figure 1). The spike is caused by low energy x rays (which are strongly attenuated by the steel cassette)
Of the ' films exposed to penetrating the film port on the side of the cassette.
Xenon gas, the lowest exposure was G.5 mit. For this exposure levci, the cyclical pattern and the spike were distinct.
The pattern on the Middletown sample was much less distinct than this and no evidence of a spike was seen.
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h To inside of roll of film %
N Figure 1.
'ILc films obtained from Pennsylvania, with the exception of Middletown, present no evidence of Xenon or other radiation exposure to the sito at which the films were obtained.
Fog levcis measured on all pennsylvania sampics were consistent with one another, with fog levcis found' on Maryland samples and with the expected fogging of Kodacolor 400 film.
If all fogging of the Pennsylvania samples were due to -
radiation, exposure to the film cassette would be less than 5 mII. One film of the G
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from Middictown possibly had a cyclic pattern (which could be attributed to cither radiation or a physical effcet). The fog level on this film was the same as the other 5 from Middletown, about 0.025 above the 0"F control film.
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d ',1VQ Ralph E. Shuping, Sc.D.
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