The thermal neutron capture cross section and resonance capture integral of 35Cl for (n, γ) and (n, p) reactions

Evidence of neutron leakage at the Fukushima nuclear plant from measurements of radioactive35S in California

“…Here, using measurements of radioactive 35 S contained in sulfate aerosols and SO 2 gas at a coastal site in La Jolla, California, we show that nearly 4 × 10 11 neutrons per m 2 leaked at the Fukushima nuclear power plant before March 20, 2011. A significantly higher 35 SO 4 2− activity as measured on March 28 is in accord with neutrons escaping the reactor core and being absorbed by the coolant seawater 35 Cl to produce 35 S by a (n, p) reaction. Once produced, 35 S oxidizes to 35 SO 2 and 35 SO 4 2− and was then transported to Southern California due to the presence of strong prevailing westerly winds at this time.…”

“…A significantly higher 35 SO 4 2− activity as measured on March 28 is in accord with neutrons escaping the reactor core and being absorbed by the coolant seawater 35 Cl to produce 35 S by a (n, p) reaction. Once produced, 35 S oxidizes to 35 SO 2 and 35 SO 4 2− and was then transported to Southern California due to the presence of strong prevailing westerly winds at this time. Based on a moving box model, we show that the observed activity enhancement in 35 SO 4 2− is compatible with long-range transport of the radiation plume from Fukushima.…”

“…Based on a moving box model, we show that the observed activity enhancement in 35 SO 4 2− is compatible with long-range transport of the radiation plume from Fukushima. Our model predicts that 35 SO 4 2− , the concentration in the marine boundary layer at Fukushima, was approximately 2 × 10 5 atoms per m 3 , which is approximately 365 times above expected natural concentrations. These measurements and model calculations imply that approximately 0.7% of the total radioactive sulfate present at the marine boundary layer at Fukushima reached Southern California as a result of the trans-Pacific transport.…”

“…Once produced, 35 S oxidizes to 35 SO 2 and 35 SO 4 2− and was then transported to Southern California due to the presence of strong prevailing westerly winds at this time. Based on a moving box model, we show that the observed activity enhancement in 35 SO 4 2− is compatible with long-range transport of the radiation plume from Fukushima. Our model predicts that 35 SO 4 2− , the concentration in the marine boundary layer at Fukushima, was approximately 2 × 10 5 atoms per m 3 , which is approximately 365 times above expected natural concentrations.…”

“…A consequence is that salts and minerals present in seawater become radioactive by reaction with thermal neutrons emitted from the reactor. For example, nuclear detonation in seawater produces 35 S by slow neutron capture by 35 Cl via the (n, p) reaction (2 35 Cl½n;p 35 S has a substantial cross-section of 0.44 AE 0.01b for thermal neutrons (4,5). 35 S is also produced via 34 Sðn;γÞ 35 S, but approximately 200 times less than 35 Clðn;pÞ 35 S (2).…”