ML19261F053
| ML19261F053 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/23/1972 |
| From: | US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| Shared Package | |
| ML19261F050 | List: |
| References | |
| NUDOCS 7910180668 | |
| Download: ML19261F053 (2) | |
Text
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t ALKALINE S0DIC! THIOSULFATE SPRAYS The staf f has concluded that an alkaline sodium thiosulf ate solution has been demonstrated to have both adequate chemical stability and iodine removal and retention capability to be conditionally acceptable for use under post - LOCA conditions.
The decomposition reaction, due to thermal and radiation ef fects, has been determined to yield only very small quantities of solid products as long as a solution pH of greater than 7.5 - 8.0 is maintained.
The decomposition rate has been found to be sufficiently slow to maintain sod.um thiosulfate in the solution for a time period adequately long to perform the primary function of iodine removal Acceptability of an alkaline sodium thiosulfate solution is based on the following criteria which the applicant meets:
1.
ability to monitor the solution pH under post - LOCA conditions 2.
capability to replenish the sodium hydroxide to maintain a minimum solution pH of 8.0 3.
minimum use of aluminum and copper containing materials which come in contact with the spray or sump solutions The staff has used a model for the evaluation of the effectiveness of the alkaline thiosulfate sprays similar to that currently used for the evaluation of sodium hydroxide systems, but differing in several important aspects.
These modifications include a change in the value 1486 168
'910 180 66g
~
. of the iodine deposition velocity to allow for decreased liquid film resistance, credit for limited removal of organic iodides by the sprays, end a revision of the ultimately attainable maximum decontamination factor for inorganic iodides to 1000.
These changes retain a degree of conservatism comparable to that applied to sodium hydroxide systems.
The two hour dose reduction factor is 5.55 for a spray removal constant
-1 of 7.56 hr~
for elemental iodine,.45 hr for particulate iodine and
.10 hr" for methyl iodide.
1486 169
.