Quote:– 2 hrs 26 mins ago

(Reuters) – Radiation was leaking from an unstable nuclear reactor north of Tokyo on Saturday, the Japanese government said, after an explosion blew the roof off the facility following a massive earthquake.

The development has led to fears of a disastrous meltdown. Here are comments from experts about what might have happened.

PROF PADDY REGAN, PROFESSOR OF NUCLEAR PHYSICS AT THE

UNIVERSITY OF SURREY

"It looks as if the coolant pumps had initially stopped working. They shut down automatically when the reactor shuts down, but there is a backup system running off a diesel generator -- it looks as though that's the bit that failed.

"As a result there is no way of pumping heat out of the reactor, so it has to cool naturally. If the reactor gets too hot, in principle this means the fuel rods can melt - but it looks unlikely this has happened to any great extent in this case.

"To reduce the pressure, you would have to release some steam into the atmosphere from the system. In that steam, there will be small but measurable amounts of radioactive nitrogen - nitrogen 16 (produced when neutrons hit water). This remains radioactive for only about 5 seconds, after which it decays to natural oxygen.

"But if any of the fuel rods have been compromised, there would be evidence of a small amount of other radioisotopes in the atmosphere called fission fragments (radio-caesium and radio-iodine).

"The amount that you measure would tell you to what degree the fuel rods have been compromised. Scientists in Japan should be able to establish this very quickly using gamma ray spectroscopy as the isotopes have characteristic decay signatures. Current reports seem consistent with a small leak to relieve pressure."

"But we still need to establish the cause and exact location of the explosion, which is a separate issue. So far it looks like it's not the reactor core that's affected which would be good news.

"We must remember that there are 55 reactors in Japan and this was a huge earthquake, and as a test of the resilience and robustness of nuclear plants it seems they have withstood the effects very well."

Quote:TOKYO (Nikkei)--The Nuclear and Industrial Safety Agency (NISA) said Saturday afternoon the explosion at the Fukushima No. 1 nuclear plant could only have been caused by a meltdown of the reactor core.



The same day, Tokyo Electric Power Co. (9501), which runs the plant, began to flood the damaged reactor with seawater to cool it down, resorting to measures that could rust the reactor and force the utility to scrap it.



Cesium and iodine, by-products of nuclear fission, were detected around the plant, which would make the explosion the worst accident in the roughly 50-year history of Japanese nuclear power generation.



An explosion was heard near the plant's No. 1 reactor about 3:30 p.m. and plumes of white smoke went up 10 minutes later. The ceiling of the building housing the reactor collapsed, according to information obtained by Fukushima prefectural authorities.



At a news conference Saturday night, Chief Cabinet Secretary Yukio Edano discounted the possibility of a significant leak of radioactive material from the accident. "The walls of the building containing the reactor were destroyed, meaning that the metal container encasing the reactor did not explode," Edano said.



The amount of radiation detected inside the plant after 4:00 p.m. slightly exceeded the dose people can safely receive in a year, according to information obtained by the Fukushima prefectural government.



The No. 1 reactor shut down automatically soon after a massive earthquake hit the area Friday, but its emergency core cooling system failed to cool the reactor's core sufficiently.



NISA is affiliated with the Ministry of Economy, Trade and Industry.

Quote:(Reuters) - Nuclear fuel rods at a quake-stricken Japanese nuclear reactor are now fully exposed, Jiji news agency said, quoting the plant's operator, Tokyo Eletcric Power Co

Quote:Seventeen U.S. Navy crew members have been contaminated with low-levels of radiation during disaster relief missions in Japan, military officials said Monday.



The radioactivity was detected when the service members returned to the aircraft carrier Ronald Reagan aboard three helicopters. They were treated with soap and water and their clothes were discarded.



"No further contamination was detected," the military said.



The helicopters were also decontaminated.



The U.S. 7th Fleet, positioned about 100 miles northeast of the Fukushima Daiichi nuclear power plant to deliver aid to Japan's coastal region, moved its ships further away due to "airborne radioactivity" and contamination found on its planes.

Quote:Two more reactors at Fukushima Daini have now achieved cold shutdown with full operation of cooling systems. Engineers are working for the same at the last unit.



The power plant's four boiling water reactors stopped automatically on last week's earthquake. At unit 3 the shutdown appears to have gone exactly as expected, with no systems damaged by the huge earthquake or tsunami. It went from power production to cold shutdown - where coolant water is at less than 100ºC - in about 34 hours.



All the reactors have remained safe, but damage to the emergency core cooling systems of units 1, 2 and 4 led to the announcement of emergency status. Those reactors used their a secondary system, the make up water condensate system, and this was used to maintain coolant levels above the reactor core. An additional emergency notice came from unit 1 concerning the temperature of a suppression chamber, which reached 100ºC after some time.



In the last 48 hours, Tepco has carried out repairs to the emergency core coolant systems of units 1, 2 and 4 and one by one these have come back into action. Unit 1 announced cold shutdown at 1.24 am today and unit 2 followed at 3.52 am.



Repairs at unit 4 are now complete and Tepco said that gradual temperature reduction started at 3.42pm. An evacuation zone extends to ten kilometres around the plant, but this is expected to be rescinded when all four units are verified as stable in cold shutdown conditions.

Quote:The Japan-based Indian employees of Infosys Technologies are returning to India, its chief executive said, as panic swept Tokyo after a rise in radioactive levels around an earthquake-hit nuclear power plant. "Some of them have returned, some are in the process of coming back," S Gopalakrishnan sai Indian software firms ready to relocate Japan staff

d. "The revenue from Japan is very small and overall it will have a minimal impact on business."



Infosys, India's second-largest software services exporter, has about 500 employees in Japan out of which 350 are from India, he said.

Quote:By Sudha Ramachandran



BANGALORE - The nuclear disaster looming at the Fukushima Daiichi plant in Japan in the wake of Friday's devastating earthquake and tsunami has sparked debate over the safety of India's nuclear drive. While the [url="http://www.atimes.com/atimes/South_Asia/MC17Df02.html#"][color="green"]government[/color][/url] has gone into overdrive to allay public apprehensions over the safety of Indian reactors, several experts and activists remain unconvinced. .. . . . .... Several of the top brass of India's nuclear establishment have come out in defense of the nuclear reactors. "All our plants have been tested to withstand earthquakes and tsunamis.

Seeking to reassure the country, Prime Minister Manmohan Singh told parliament on Monday that an "immediate technical review of all safety systems in nuclear power plants" would be carried out to ensure that they would be able to "withstand the impact of large natural disasters such as tsunamis and earthquakes".



Nuclear experts are underlining that the type of reactors in India and Japan and the environment in which they operate are different; hence similar scenarios are unlikely.



Unlike Japan's nuclear plants which are located in highly seismic areas (Fukushima is located in Zone 5) most of India's nuclear plants are situated in the moderately seismic Zone 3. The Narora plant is the only one located in Zone 4. Officials rule out the possibility of an 8.9 magnitude earthquake striking Indian nuclear plants since none of them are located in the highly seismic Himalayan region.



Besides, Indian nuclear plant structures, systems and equipment are designed to withstand the maximum possible earthquake at their location, says Shashikant Dharne, joint director at the Nuclear Power [url="http://www.atimes.com/atimes/South_Asia/MC17Df02.html#"][color="green"]Corporation[/color][/url] (NPC).



Indeed quakes and tsunamis have done little damage to nuclear reactors in India. The Narora plant has not been damaged in the several tremors it has experienced in the past 21 years it has been in [url="http://www.atimes.com/atimes/South_Asia/MC17Df02.html#"][color="green"]operation[/color][/url], including one of 6.3 magnitude.



When an earthquake of 6.7 magnitude hit Gujarat in 2001, operations at the Kakrapur plant went on uninterrupted. When the 2004 tsunami battered the Tamil Nadu coast, the Kalpakkam nuclear power plant's grounds were flooded, and the reactor went through an automatic shutdown process and did not operate for a few days. According to P K Iyengar, former chairman of the AEC, the decision to install its electrical systems 17 meters above the ground, prevented damage to the reactor.



"Indian reactors are inherently safer as they use natural uranium as fuel as against enriched uranium that the Japanese reactors use," says Pallava Bagla, a science journalist with NDTV. They also "use a double containment as against the single containment used in Japan". Besides, the reactor design "allows for cooling using convection currents even in a state of station blackout - when all power and backups fail," points out Om Pal Singh, an expert on nuclear design safety at the Indian [url="http://www.atimes.com/atimes/South_Asia/MC17Df02.html#"][color="green"]Institute of Technology[/color][/url] at Kanpur.



Officials point out that 18 of India's 20 reactors are indigenously built, pressurized heavy water reactors (PHWRs) and only two - those at Tarapur - use boiling water reactors (BWRs) as did those in Fukushima. They admit that like the facility at Fukushima, the Tarapur Atomic Power Station (TAPS) is an old plant. But TAPS was renovated and additional safety features consistent with latest safety standards were added, they argue.



Not everyone is convinced of the safety of India's nuclear reactors or of the country's preparedness to respond to a nuclear disaster.



Many fear that if Japan - a country known for its quiet efficiency and discipline as well as its immense expertise in earthquake and tsunami-resistant design - has not been able to prevent explosions in its nuclear facilities, there is little chance that India, which is notorious for its chaos and the low priority it accords to public safety, will be in a position to do so.



"We are most disorganized and unprepared to handle emergencies of any kind of even much less severity," A Gopalakrishnan, former chairman of the Atomic Energy Regulatory Board (AERB) told Asia Times Online. "The AERB's disaster preparedness oversight is mostly on paper and the drills they conduct once in a while are half-hearted efforts, which are a sham," he said.



India's nuclear top brass insist that safety audits of nuclear plants are taken seriously in the country. Nuclear plants need clearance from the AERB every five years and safety audits are mandatory for relicensing, Nuclear Power Corporation of India, Ltd (NPCIL) chairperson S K Jain told the media in the wake of the disaster in Japan.



However, a mandatory safety audit alone does not make reactors safe. Who conducts the audit is important. And in India, the body that does the audit is not autonomous. The AERB draws its personnel from the Department of Atomic Energy (DAE) and reports to the AEC.



It "merely serves as a lapdog of the DAE and the Prime Minister's Office. With a captive AERB reporting to the DAE, overall nuclear safety management in India has been rendered worthless," Gopalakrishnan pointed out.



"The earthquake-resistant designs and tsunami abatement measures adopted in India's nuclear plants need a high-level, in-depth review by an independent expert group, consisting of experts outside of the DAE and the NPCIL," he said. "But there is practically no independent verification of data or design methodologies."



"This is no way to run a critical safety regulatory function," writes activist Prabir Purkayastha, describing the lack of a separation in the regulatory and operational functions in nuclear energy as the "single-biggest obstacle for a safe nuclear energy program in the country".



A culture of opacity surrounds India's nuclear establishment. It is not just the nuclear weapons program that is shrouded in secrecy. Little is known about the civilian nuclear program and the functioning of bodies like the AEC and the AERB. In the circumstances, the veracity of audits is hard to accept.



"Audits conducted in the past did reveal loopholes in safety measures at nuclear reactors but these findings were never made public," a senior official at the Kaiga nuclear plant told Asia Times. "Worse, there was little follow-up action."



Activists say they are not expecting anything to come of the prime minister's promised audit of nuclear reactors. "We can already predict the report - all we need to do is to listen what the nuclear establishment has been saying for the last few days and we will know what the report is likely to say," observes Purkayastha.



The explosions at the Fukushima nuclear plant have revived opposition to the proposed nuclear plant - the world's largest - at Jaitapur in Maharashtra's Konkan region. While Jaitapur's proponents say it is in a seismically safe area - it is in Zone 3 - activists point out that it is located in a region that has been hit by three severe earthquakes of a magnitude exceeding 5 points over the past two decades, including one in 1993 that left almost 10,000 people dead.



Questions have also been raised over the safety of Jaitapur's reactors. India plans to purchase six European Power Reactors (EPRs) from the French company [url="http://www.atimes.com/atimes/South_Asia/MC17Df02.html#"][color="green"]Areva[/color][/url] for Jaitapur. The EPR is of unproven design and the first unit has already run into trouble with British and Finnish nuclear regulators drawing attention to serious design deficiencies in its control and safety systems.



Given that India built on its own 18 PHWRs, three generations of Indian engineers and scientists are familiar with PHWR technology. "The safest route is to consolidate and expand on our PHWR experience, import natural uranium and build more PHWRs," Gopalakrishnan said. Instead the government is [url="http://www.atimes.com/atimes/South_Asia/MC17Df02.html#"][color="green"]purchasing[/color][/url] French EPRs in Jaitapur, of which neither Indians nor the French, know much about.



"If a major accident occurs in a PHWR, we have Indian engineers and scientists who are totally familiar with the technology, who can jump in and rapidly bring the situation to normal. For Indian engineering teams to react in a similar timely and effective manner against an accident in one of the planned imported reactors will be next to impossible for at least few decades to come," Gopalakrishnan said.



In the next few years, India plans to spend billions of dollars on importing reactors. The explosions at Fukushima may compel the government to believe that this might not be the safest option.



Sudha Ramachandran is an independent journalist/researcher based in Bangalore.

Quote:2011-03-16 16:50:00

New Delhi, March 16 (IANS) Even as Japan deals with the threat of a nuclear meltdown in the wake of a devastating earthquake and tsunami, Prime Minister Manmohan Singh held a meeting Wednesday with the heads of the Atomic Energy Commission (AEC) and the Atomic Energy Regulatory Board (AERB) to review the safety measures of nuclear installations in India, sources in the PMO said.



On Monday, in a statement in parliament, the prime minister had assured that Indian nuclear power plants would undertake an immediate technical review of all safety systems to ensure that they are able to withstand large natural disasters.



According to PMO sources, the AEC and AERB chiefs briefed the prime minister about the technical safety systems in place in existing power plants in India.



India has 20 nuclear power reactors, out of which only two at Tarapur are boiling water reactors of the type at the Japan's Fukushima Dai-ichi nuclear plant, where three of its six reactors were hit by explosions and a fourth caught fire in the aftermath of the earthquake. A fresh fire broke out Wednesday in a reactor in the plant.



While the earlier explosions took place due to the failure of the cooling systems, there have been more serious apprehensions about the integrity of the stored spent fuel rods being damaged due to fire.



Indian officials said there was not much worry of a similar situation arising in India.



'We asked the AEC and the Department of Atomic Energy the same question, and what they tell us is that here the designs are different, the storage of spent fuel is different,' National Security Advisor Shivshankar Menon said during an interaction at the Indian Women's Press Corps.



He added that DAE officials had noted that a scenario here as in Japan 'was most unlikely'.



At the same time, officials were closely monitoring the situation in Japan and were hoping to learn from it to further strengthen India's nuclear safety measures, said Menon.

1. After earthquake Japanese reactors were shut down. But they are light water cooled design, that have far different meltdown failure risk compared to Heavy Water cooled Indian PHWR.
2. Almost all reactors are natural Uranium fed core, thus core size is big, and cooling is much easier.
3. Most Japan failures are due to residual heat when reactor is shutdown. Their enriched core design result in high flux even when spent fuel is taken out of reactor. So the heat flux is also high.
4. Only FBR and Tarapur use higher enrichment fissile fuel.
5. Kalapakkam did pretty well against last Indian Ocean Tsunami
6. AHWR design is based on learning from PHWR, with various levels of emergency protection, moving more towed passive protection features as against active protection that depend on pumps, generators etc.

Quote:TOKYO (Nikkei)--Japanese officials have installed cables to supply electricity from Tohoku Electric Power Co.'s (9506) power grid to the Fukushima Daiichi nuclear power plant, a step they hope will help inject water more efficiently into the facility's crippled reactors that are at the center of Japan's nuclear crisis, the government's Nuclear and Industrial Safety Agency said at a news conference Thursday night.



Officials will try to connect the cable to the plant's No. 2 reactor on Friday, the agency said.



The No. 2 reactor's containment vessel was partly damaged in its pressure suppression chamber. The reactor building is emitting vapor deemed to have originated from spent nuclear fuel's storage pools into the air.



Tokyo Electric Power Co. (9501), which operates the plant, will try to restart the No. 2 reactor's cooling system Friday by using the power supply from Tohoku Electric, officials said.