<Reference> Development of a technology to investigate inside the Reactor Primary Containment Vessel (PCV) - Results of follow up check after the site test - [For April 18 and 19, 2015] April 20, 2015 Tokyo Electric Power Company The content of this material includes the output of the International Research Institute for Nuclear Decommissioning (IRID)
1. Check items The following items were checked on the counterclockwise route. Route of remaining cable, Degree of interference of remained cables at the opening to access the basement, Status of the investigation device blocked in the vessel, and Access route to the CRD rail. CRD rail C11, C10, C9, C8, C7, C6, C5, C4, C3, C2, B1, B2, C1, C0, B0, Spot where the investigation device blocked on the counterclockwise route. (Apr. 10) The opening to access the basement. X-100B 1
2. Status of the cable remained The route of remaining cables is shown as below. It was confirmed that the remaining cable around the opening to access the basement will be no obstacle to B2 investigation. X-6 Penetration Spot where the investigation device blocked. Pedestal Opening (D) X-100 B penetration pipe Opening to access the basement : the part the cable attached on floor.. : the part the cable is floating. 2
3. Status of the investigation device blocked The situation of the investigation device blocked is shown as below, which is almost compatible with what has been assumed. Structural object Gap at the wide point (Space with one step lower) B1, B2, B0, Grating Crawler on right side was stuck and contacted with the structural object. Investigation device (Final position ) Images captured by the investigation device The investigation device blocked Structural object 3 3
4. Check on the access route to CRD rail It was judged that the suggested access route to CRD rail would be too narrow to get the device pass through between the two structural objects. Suggested access route Structural object B1, B2, Structural object Investigation device blocked Shooting range B0, Images captured by the investigation device Investigation device Suggested access route 4
5. Collection of the investigation device Earning information inside the reactor primary containment vessel, which is the main purpose of this investigation, has been achieved. Due to the deterioration of the monitoring camera with radiation, it became disabled to perform a deformation check on the device. Accordingly, the collection of the device to outside the reactor primary containment vessel has been judged as risky. (* 1 ) PCV X-100B penetration Bldg. concrete Bellows part of guide pipe Device hatch monorail Guide pipe CRD Support beam * 1 Having found that there is a slight unevenness at the bellows part of guide pipe when inserting the investigation device, there is a risk that the device might get stuck when its passing though the bellows. Monitoring camera In order to collect the device from the grating floor, check the deformation degree of the device. 1F Grating Investigation device 5
6. Leaving the investigation device Locations where the devices are left are shown as below. Those are places that are able to retain the devices in a stable state. The remaining devices will be no obstacle to B2 investigation. CRD rail MS pipe : Access route investigated (counterclockwise route) : Access route investigated (clockwise route) C11, Pedestal Opening Spot where the device is left on the counterclockwise route. C10, C9, C8, C7, C6, C5, Spot where the device is left on the clockwise route C4, C3, C2, B1, B2, C1, C0, B0, X-100B penetration pipe Opening to access the basement 6
(Reference) Measurement on temperature/ dose rate Temperature and dose rate were measured at the following points. CRD rail Pedestal opening Measurement taken: April 19, 2015 Dose rate (Sv/h) Temperature ( ) Around B14 4.4 17.9 Around B11 5.7 18.7 Around B7 5.9 19.1 C5, C4, C3, C2, C1, C0, B0, B1, B2, Final point (around C3) 4.1 20.4 X-100B 7