Nixon was exposed to potentially harmful ionising radiation while staying at the US ambassador’s residence in Moscow during the first days of his trip, said secret service documents obtained by the National Security Archive at George Washington University.
He was vice president at the time.
The threat was not made known to the vice president following a decision taken by then US envoy to Moscow, Llewellyn Thompson, and a senior member of Nixon’s entourage, Vice Admiral Hyman Rickover.
The state department was informed of the incident 17 years later in 1976, when a member of Nixon’s secret service team, James Golden, revealed detection equipment known as Radiac Dosimeters, had “measured significant levels of radiation” in and around the vice president’s sleeping quarters at Spaso House.
Golden claimed he was later informed that he had been exposed to “massive dosages” of ionising radiation emanating from an atomic battery used by the Soviet intelligence to power bugging devices such as radio transmitters.
Analyst William Burr, who made the request to the Nixon Presidential Library to obtain the records, said: “This unusual and virtually unknown Cold War episode deserves more attention so the mysteries surrounding it can be resolved.”
The Spaso House was reportedly the location of a previous Soviet eavesdropping operation.
American technicians in 1952 discovered a small, sophisticated listening device hidden in a wooden carving of the “Great Seal” of the US, which was a gift from Soviet girl scouts to the wartime and post-Second World War US ambassador Averell Harriman in 1946.
The device remained a secret for six years because its power source was generated by radio frequency waves beamed at Spaso House from a “van parked across the street”.
Prior to his visit to Soviet Moscow, Nixon was asked by a member of his secret service if he wanted radiation detection devices taken on the trip. The vice president agreed to more discreet dosimeters, while refusing to wear one himself to keep the discussion a secret.
On 23 July 1959, dosimeters brought to detect the radiation levels provided readings of up to 15 roentgen per hour during an inspection of Nixon’s quarters.
While the levels were far from lethal exposure, the permissible standard for occupational exposure in the US was 5 roentgen per year.
Assuming the rooms were bugged after the discovery of radiation levels, secret service agents, the next morning, started “berating the Russians in loud voices” and “cursing them for pulling a trick like this”.
“We sat down on the beds facing each other and began berating the Russians in loud voices cursing them for pulling a trick like this and wondering in loud voices why they were taking us for fools and asking each other if they thought they were going to get away with doing this,” Golden said.
The radiation stopped by the afternoon.