In November 1957, staff at the Atomic Energy Commission, penned a report to the commissioners entitled “Status of Research and Development on Reactor Pressure Tubes.” If any decent-sized reactor was cooled by a gas, it needed to be held under pressure, either in a big ultra-strong pressure vessel or in tough tubes. America didn’t use tubes, only the Canadians and Soviets did. Here’s how the AEC staff summed up:
High thermal efficiency in a power reactor can only be attained with the coolant circulating at high temperatures and (with most coolants) high pressures. The moderator, however, may be effective at low pressures. Accordingly, the use of pressure tubes for circulating the coolant within a reactor offers the possibility of lower cost construction of the moderator vessel because this vessel would then have to withstand the relatively low pressure of the moderator. The use of pressure tubes seems especially desirable in designs using heavy water or graphite moderator and natural (or slightly enriched) uranium fuel when the lattice requirements would call of especially large pressure vessels. To date studies have indicated that no clear-cut economic advantage can be claimed for the pressure tube concept except, possibly, for very large reactors.
AEC. 1957. Status of Research and Development on Reactor Pressure Tubes. “Reactor Development 12,” Box 114, Entry 67-B1, RG 326. NARA II, College Park, Maryland.
The United States never did have a go at pressure tubes. Whether this was a sound decision is not yet clear to me, mainly because the first volume of my reactor history series closes at the end of 1957, and I haven’t worked through later years.
