Step 2. Remove the dosimeter from the charger and observe the reading.
Step 3. Repeat Steps 1 and 2 until a zero reading is obtained after the dosimeter has been removed
from the charger. A zero reading on the dosimeter must be obtained after the dosimeter has been charged
and checked.
e. After-operation procedures. After the PP-1578A/PD charger has been used, return it to its
carrying case in the following manner:
Step 1. Unscrew the adapter, if used, from the charging pedestal and place it in its container in the
carrying case.
Step 2. Screw the dust cover into place over the charging pedestal.
Step 3. Place the assembled charger in its carrying case and fasten the flap.
after no more than two or three days of use. They must also be recharged when the total dose reaches or
exceeds 500 cGy on the scale. Recharging times are normally designated in the unit's standing operating
procedure (SOP).
2-11. Procedures for Leakage Testing. The charge that is placed on the dosimeter will gradually leak,
even though the dosimeter is not exposed to radiation. This leakage, if excessive, will cause an improper
reading on the dosimeter during use. The leakage should not be more than 2 percent of the full-scale
reading per day for a good dosimeter. Check the leakage rate as follows:
NOTE: If the dosimeter has not been charged for an extended period of time or has been stored in
an uncharged condition and is then fully charged, excessive leakage may occur. This excessive
leakage is due to insulation soak-in, penetration of part of the charge into the insulation. Do not
perform a leakage-rate check on the dosimeter until it has been charged to zero for five consecutive
days. Ignore the daily leakage that may occur during this period.
Step 1. Charge the dosimeter to read zero on the calibrated scale.
Step 2. Store the dosimeter in a radiation-free area for a 24-hour period.
Step 3. Note the reading on the dosimeter's calibrated scale. This reading represents the leakage
rate in cGy per day.
NOTE: If the leakage-rate reading for a period of one day is difficult to determine, the charged
dosimeter may be allowed to set for several days until a readable value can be obtained. When the
reading is obtained, divide the total reading by the number of days that the charged dosimeter was
allowed to set to obtain the average daily leakage rate.
Step 4. If the leakage rate is greater than 12 cGy per day for the IM-93/UD or IM-93A/UD, or 1
cGy per day for the IM-147/PD, clean the charging end of the dosimeter.
Step 5. Recheck the leakage rate following Steps 1 through 4. If the leakage rate is still greater
than the values given in Step 4, the dosimeter is defective and should be replaced. The acceptable leakage
rate per day for each of the dosimeter models is--
2-13
CM2306
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