The US Navy operates more than 80 nuclear-powered ships, with 103 reactors. Naval reactors run on uranium (U235) fuel, enriched 90% to 95% while civil power reactors run on only 3%to 5% enriched fuel. Naval reactors do not have emergency core cooling, which is standard for civil reactors .

At least five political parties -- the CPI and CPI(M), the AIADMK, the MDMK and the PMK have questioned the government's decision to permit the USS Nimitz to anchor at Chennai's outer harbor. It has two Westinghouse A4W reactors and 5,680 sailors and airmen on board.

At issue for environmentalists and peacenicks also is whether these ships are nuclear armed as well. American policy is to 'neither confirm nor deny' this. 

An American consulate statement here called the Nimitz visit "a
landmark event" and added that the was 'as part of a bilateral and multilateral framework known as the 'Malabar series' of joint Indo-US
exercises'. 

A high-level Indian naval security team, said to be led by M. K. Agarwal, went on board the USS Nimitz, when it was about 10 nautical miles away from the port, to make a safety assessment. 

The row over Nimitz began when the Chennai Port Trust issued a circular to officials "to be prepared to tackle any emergency" during the vessel's visit. 

The circular asked the port's chief medical officer to keep ready a nuclear medicine team to handle any contingencies. Medicines will be provided by the Department of Atomic Energy, the circular said. 

The government of India too issued an alert for the Nimitz visit. "The procedure that is followed for any nuclear powered ship or submarine berthing in any Indian port is well established since 1988," a defence ministry statement said. 

"An Environmental Survey Committee (ESC) has carried out a detailed survey at Chennai and cleared the visit of USS Nimitz from the radiation hazard point of view," it said. 

A stringent radiation monitoring protocol is also in place that shall, "at periodic intervals, monitor and analyze air and water samples," the statement said. 

"These activities shall be conducted under the ambit of a well rehearsed Radiation Safety Contingency Plan under the stewardship of a Crisis Management Group and Crisis Management Cell comprising scientists from DRDO (Defence Research and Development Organisation), BARC (Bhabha Atomic Research Centre), the Defence Laboratory at Jodhpur and representatives of the Chennai Port Trust and the Indian Navy," the statement added. 

Radiation monitoring laboratories manned by scientists of the DRDO and the BARC, as also defence personnel, are set up onboard a suitable ship to undertake frequent monitoring of water and air samples. 

The Indian safety protocol is two- tiered and emphasizes that no other ship can berth within a 200-metre radius of a nuclear powered ship, and ships within 600 metres of the berthed vessel are put on short notice. 

The document, 'OPNAVINST 3040.5B, Nuclear reactor and radiological accidents; procedures and reporting requirements for', is issued by the chief of US Naval Operations. 

It tells nuclear-powered US ship commanders, they are free to use their 'judgment as to the nature and extent of an accident'.

It also tells them that they 'may not need to contact all the relevant authorities', like foreign governments, when a nuclear-powered vessel has an accident in a foreign port, Wills pointed out. 

The US government also has a 'Standard Statement on the operation of U.S. nuclear powered warships in foreign ports' which says, 'the appropriate authorities of the host government will be notified immediately in the event of an accident involving the reactor of the warship, during a port visit'. 

This is not a document in the public domain and the OPNAVINST document nullifies the assurance given by the USA in the 'Standard Statement', Wills told the New Zealand parliament, after a three-year inquiry by its neighbor, the Australian Senate, concluded: 'there is a total lack of knowledge of the contingency procedures that the US authorities would implement in the event of a reactor incident'.

Both Australia and New Zealand have been resisting the parking of nuclear powered ships into their harbors.

The US Navy document says, 'if a commander judges' that panic and stoppage of vital services may have more serious consequences than exceeding specified levels of public exposure to radiation, then civilian authorities need not be notified. 

'Public reaction' is noted as a specific factor for consideration in relation to deciding what actions should be taken. 

Before a US nuclear-powered warship is allowed to visit a foreign port, the chief of naval operations makes a 'reactor safeguards evaluation'. The criteria used for this evaluation are secret and classified. 

'Whatever they are up to when they send a nuclear-powered warship into a foreign port, it is much more secret than spying on foreign governments', Wills told the New Zealand panel. 

'In the event of an accident, the release of information would be limited to that required for public safety, and there would be no discussion of the reasons for the accident', Wills pointed out. 

Loss of radioactivity from a warship does not constitute a 'radiological accident' until projected public exposure to radiation reaches a pre-determined level. 

The US Navy may decide no public notification is necessary. 'In such a case, the government hosting a visiting nuclear-powered warship is also unlikely to be informed', Wills told his parliament. 

The notification procedure is time taking too. 

At the first sign of an accident, the captain orders a radioactivity survey on board. He assesses 'whether or not' an 'accident situation' exists, then notifies his superiors and dispatches a radiological monitoring team ashore to survey the downwind situation. 

The survey result is then reported to an 'area commander' at fleet headquarters. The area commander, in turn, decides whether or not an 'accident situation' exists. 

The area commander then directs mobilization of personnel and resources from a remote 'emergency control centre' . 

'The views of local authorities would not be sought, not even to confirm that they coincide with the judgments of the US Navy', Wills told his country. 

'The standing instructions to US Navy commanders usurp the authority of those responsible for public safety and are irreconcilable with assurances offered to foreign governments in the Standard Statement', said Wills after analyzing the OPNAVINST 3040.5B document.

The US Consulate General in Chennai, in a statement on June 26, said, "There has never been a nuclear accident in the 56-plus-year history of the programme. US Navy nuclear-powered warships have steamed more than 135 million miles and amassed more than 5,700 reactor-years of safe operating experience', adding that the 'safety record of the US nuclear-powered warship is outstanding". 

After the attack on the destroyer USS Cole in Aden in 2000, the US Navy recognizes that nuclear-powered warships in port are prime terrorist targets. 

Indian politicians like J Jayalalitha have said, "This is a serious issue and the possible radiation hazards to the people of Chennai cannot be taken lightly".

MDMK leader Vaiko has noted that, 'as Kalpakkam and Koodankulam atomic power stations were located on Tamil Nadu's coast, there is a fear that the visit of a nuclear-powered warship to the port here would endanger the country's security'.