Sentence:  Upon the expiration of a period deemed adequate for demonstration purposes for each plant , but not to exceed such twelve year period , the Secretary shall proceed as promptly as practicable to dispose of any plants so constructed by sale to the highest bidder , or as may otherwise be directed by <WSD>Act</WSD> of Congress . 
Meaning of the word marked with <WSD> tags:  a legal document codifying the result of deliberations of a committee or society or legislative body