They were national strategic programs. The strategic programs were aligned with nuclear weapons programs. The government picked and enforced a single design for all of the reactors. The reactors were GW-scale due to thermal efficiencies required for cost effectiveness. The government ran human resourcing. The programs ran for 20 or 30 years. They built dozens of nuclear reactors to maintain the teams and momentum and to share lessons learned.

Blockchains and distributed ledgers also use SMR, in which casethe chain of blocks (and the transactions therein) constitutes theevent log, the ledger (e.g. the balance of every account) is the result-ing state, and smart contracts or the network’s built-in transactionprocessing logic are the state transition function [66].

Nuclear reactors are large because of economies of scale. A reactor that produces three times as much power as an SMR does not need three times as much steel or three times as many workers. This economic penalty for small size was one reason for the early shutdown of many small reactors built in the U.S. in the 1950s and 1960s.