Gamma dose rate in the vicinity of JCO as of approximately 8:00 pm on September 30, 1999

While the criticality was continuing at the uranium conversion building of the JCO Company Limited, Tokai, Japan on September 30, 1999, the gamma dose rate was measured by carborne GM survey meters. The maximum dose rate along Route 6, 20.8 μSv/h, was observed at a distance of 280 m from the source at 16:45 on September 30, 1999. Along Prefectural road 62, the maximum dose rate, 510 μSv/h, was recorded at a distance of 70 m from the source at about 20:00 on September 30, 1999.