Fluor Constructors Inc., a Fluor Corp. subsidiary, has received contracts to assess damages and perform repair work at the Hawkeye Chemical Co. ammonia plant in Clinton, Iowa. Value of the contract was not disclosed. The Hawkeye plant was damaged in July when compressor housing exploded. The plant, originally built by Fluor in 1963, is expected to resume partial operations in December. Completion of the entire project is scheduled for March 1986.