ML19256D260
| ML19256D260 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/26/1971 |
| From: | Wilson T US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Long C US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 7910170772 | |
| Download: ML19256D260 (3) | |
Text
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m APR 2c 19 71 N'N7 C. G. Lang, Chief, PWR Branch No. 2, DRL ACRS REPORT FOR THREE MILE ISLAND 1 - ALKALINE SODIUM THIOSULFATE The staff report on the 11rree Mile Island 1 sprsy system, requested from the Site, Environmental and Radiation Safety Branch, is attached.
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T. R. Wilsen Assistant Director, DRL Enclosures Three Mile Island Sprey System Staff Ryt.
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ALF.Ai "': SODID: T"ICS1'L1 'T2 SPt?S The sta f f has ccncluded that an alkaline sodium thioculfate sol-ution has been demonstrated to have both adequate chemical stability and iodine removal and retention capability to be conditionally acceptable for use under post - LCCA ccnditions. The deccapcsition reaction, due to thermal and radiation effects, has been determined to yield only very.small quantities of solid products as long as a solution pH of greater than 7.5 - S.0 is maintained.
The decem-position rate has been found to be sufficiently slow to maintain sodium thiosulfate in the solution for a time period adequately long to perform the primary functica of iodine removal.
Acceptability of an alkaline sodium thiosulfate solution is based on the following criteria:
1.
ability to monitor the solution pH under post - LOCA conditions 2.
capability to replenish the sodium hydroxide to maintain a minimum solutica pH of 8.0 3.
limitation on the use of aluminum or copper containing materials which could come in contact uith the spray or sump solutions (the total weight of exposed aluminum
'hould not exceed 300-500 lbs. and the total amount of ex-posed copper should be minir.21)
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The st'.ff has used a model for the evaluation of the offectiveness of the alkalina thiosulfate sprays similar to that currently used for the evaluation of sodiua hydroxide systems, but differing in several important aspects. These modifications include a change in the value of the iodine deposition velocity to allow for decreased liquid film resistance, credit for limited recoval of organic iodides by the sprays, and a revision of the ultimately attainable maximum decontamination factor for inorganic iodides to 1000.
These changes are based on the best available data, and stain a degree of conservatism ccmparable to that applied to sodium hydroxide systems.
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