| 摘要 |
<p>PROBLEM TO BE SOLVED: To avoid extinction, which is due to electric/mechanical damage, of a radiation accumulation value. SOLUTION: As to values stored in a nonvolatile storage unit 9, a radiation quantity is added and stored, and when it is detected that stored contents reach a set value set to the upper limit value or less of the actual rewriting number of the nonvolatile storage device 9, a storage position for the value is changed, and a radiation accumulation value is found from a total of the stored storage position values, so that the extinction of the radiation accumulation value is prevented even if a power source is cut off.</p> |
