Japan Newspaper: Leaks plaguing Fukushima No. 5 reactor — Experts: Indicates “deterioration in the system” — Report: Water contains up to 3,000 Bq/liter of Cobalt-60, had been used to cool spent fuel (PHOTOS)
Asahi Shimbun, July 20, 2014: Water leaks continue to plague No. 5 reactor at Fukushima plant— A leak of radioactive water was found in the piping of water used to cool the spent fuel pool […] a sign of possible deterioration in the system. [TEPCO] said water from the cooling pond leaked […] TEPCO employee found a pool of water in each of two boxes–75 centimeters by 50 cm–that house a control valve in the cooling water piping system on the fifth floor […] The water had collected to a depth of 9 cm in one box and 18 cm in the other. The water contained 2-3 becquerels of cobalt 60 per cubic centimeter [2,000 to 3,000 Bq/liter], according to the utility. This particular piping section has been unused since July 6, when a similar leak was discovered at another section. Experts say the continuing leaks indicate that valves are deteriorating, and that the utility’s inspections are inadequate. […] the pumping of cooling water was temporarily halted after a leak in a similar piping system [inside the No. 6 reactor building] was detected on July 11.
See also: Cobalt-60 detected in Unit 4 fuel pool during first month of disaster
TEPCO official: “We are aware that our approach proved to be lax as we were unable to detect the problem until the leak occurred. We are reviewing the way checks should be conducted.”
Similar incident at Unit 5 on July 6 — Fukushima Daiichi NPS Prompt Report, Jul 8, 2014: The cooling of the spent fuel pool of Unit 5 […] was stopped due to seawater leak found at a pipe resumed cooling by another system at 15:40 today […] A system that cools the spent fuel pool at Unit 5 has been stopped on July 6 2014, after seawater was found leaking from a pipe […] the cooling of 994 fuel assemblies inside the spent fuel pool will be continued through another system […]