The report was obtained under the Freedom of Information Act
An MP has called for an investigation after it emerged that the Faslane naval base has suffered a series of safety breaches including radioactive leaks.
A report, issued under the Freedom of Information Act, showed radioactive coolant leaked from nuclear submarines on three occasions.
The Scottish National Party's Angus Robertson called the disclosures "utterly damning".
The base on the Clyde is home to Britain's Trident nuclear missiles.
Scotland's environment watchdog, Sepa, said it would have considered closing Faslane if it had had the power.
Formal legal action could not be taken because military bases are exempt from the law governing nuclear sites.
The documents also showed the Navy did not know how much radioactivity was discharged.
It is not good enough to say the MoD is exempt from radioactive safety regulations, and ministers must be held to account.
Angus Robertson MP
SNP leader at Westminster
In the report the Ministry of Defence (MoD) described the failings as a "recurring theme".
Mr Robertson, the SNP's leader at Westminster, said: "We are not talking about a one-off incident but a whole catalogue of serious and frankly shocking failures.
"Sepa's indication that it would consider closing the base, if it had the power to do so, underlines just how grave this situation is.
"It is not good enough to say the MoD is exempt from radioactive safety regulations, and ministers must be held to account.
He added: "We need an immediate and top-level investigation into this scandal."
Three times, in 2004, 2007 and 2008, radioactive coolant leaked from nuclear submarines into the Firth of Clyde.
In August 2007, the nuclear-powered submarine HMS Superb discharged water, potentially contaminated with radioactive Tritium and Cobalt-60, directly into Gare Loch.
Sepa's response was a formal letter to Faslane expressing its concern.
It noted that it had not been told about the incident for six days.
In February 2008, it happened again.
This time HMS Torbay was warming up its reactor when a tank overflowed.
Sepa issued another letter in the form of an enforcement notice.
The environment watchdog said the radiological consequences were minor.
But it was concerned proper procedures had not been followed.
An MoD spokesman said: "The discharges into the Gare Loch had no environmental consequences.
An improvement plan is currently under way to ensure modern standards and best practice at the base
"The MoD is a responsible nuclear operator and informed the appropriate regulatory authorities.
"We commissioned an independent study into the facilities and practices at HM Naval Base Clyde and an improvement plan is currently under way to ensure modern standards and best practice at the base."
Liberal Democrat defence spokesman Nick Harvey said: "This is no longer the Cold War. The MoD must operate its nuclear facilities at at least the same level of safety as civilian nuclear operators.
"Given the dire state of the MoD budget and the terrible failure of other military equipment projects like the Nimrod aircraft, the government will need to convince the public that this is not evidence of a deeper malaise in the Armed Forces.
He added: "If the MoD is incapable of safely maintaining Britain's nuclear submarines it will raise further doubts over the Government's premature decision to replace the Trident system."
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