The price of wheat and corn jumped and the stocks of utility companies that own nuclear plants plunged yesterday in response to the Soviet nuclear accident.

Speculation that Russian crops might be damaged quickly showed up in the grain futures markets. At the Chicago Board of Trade, wheat futures prices were up by 20 cents a bushel -- the daily limit for price increases -- and corn was up its 10-cent limit. Prices later receded as grain traders tried to sort out whether fallout from the accident might damage the Russian crop.

The Dow Jones average of 15 utility stocks fell 5.43 points to to 180.14, the biggest drop since the average fell 8.22 points on May 28, 1962.

"I think the situation in Russia certainly has had a ripple effect in the United States," said Joseph B. Muldoon, a utility securities analyst at Janney Montgomery Scott Inc., a Philadelphia investment firm.

"I think this reaction is the nervous nellies, not the people who know what's going on in the industry," Muldoon said.

Linda S. Caldwell, a utility analyst at the Chicago investment firm of Duff & Phelps Inc., said: "Basically, anyone building a nuclear plant got hit."

Many analysts speculated that the Soviet accident served as a convenient excuse for investors to dump their holdings in an industry that has not been doing well economically.

Norton D. Strommen, chief meteorologist with the World Agricultural Outlook Board in Washington, said the radioactive cloud from the accident traveled away from Russia's major winter grain region and has had a "minimal impact" on crops.