PIPPA and Calder Hall

The idea of getting useful power from a reactor using only natural uranium had been under consideration since the late 1940s. A report had been commissioned from the Parolle Company of Newcasde upon Tyne, who manufactured turbines and electrical generators for power stations. This was a study of the steam plant for a nuclear power station assuming that there was hot gas coming from the reactor at a temperature of 350 °C. The reactor itself was treated as a black box — in other words, there was no attempt to produce any specific reactor design.  

This paper had a very bad reception. We were accused of undue pessimism and the whole project was belittled as being retrograde and a wastefiil diversion of effort. We were strongly urged to stop work on the seheme and only the Director s casting vote saved the project from the dustbin. 

In particular, the reactor was criticised by Hinton and others at Risley as being low-rated, large and clumsy. It seemed that the gas-cooled reactor would be dropped from the power prograname for 1952. 

Unfortunately, it became clear that the critical size calculations on which the project was based were in error and that either the uranium would need enriching or the diameter of the pressure vessel would have to be increased by ten feet. Increasing the size of the pile would make the calculations more difficult, but would be more worthwhile than having to resort to eiuichment. 

In the meantime, another problem was also becoming more serious the increased requirement for plutonium for military purposes. The existing piles were not sufficient. One option was to restart work on the third pile, which had been abandoned in 1950, but another possibility seemed to be to combine the design for the new power reactor with a production reactor. This would be the origin of PIPPA and, by extension, Calder Hall. 

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The route to the magnox reactors used for the first power programme is easy to trace the air-cooled Windscale piles lead to the idea of closed-circuit gas-cooling, which in turn lead to the PIPPA design and Calder Hall. Calder Hall can be considered as a prototype for the magnox stations, and the commercial versions took the design to its limit. 

By the end of 1952 it was eertain that a PIPPA design had been produeed whieh eould and should be built. A summary report was prepared in January 1953, and soon after approval was granted for eonstmetion of the first two Magnox reaetors at Calder HaU. Before the first reaetor went eritieal in 1956 work had started on a further two reaetors at Calder Hall, and all four were at power in 1959. Constraetion at Chapeleross, in the southwest of Seotland, began in 1955. The fist... 

Needless to say, even before work had begun on what would become Calder Hall, a PIPPA Mark II was being considered. Some obvious improvements could be made, such as increasing the heat output and improving the efficiency for steam production. The Mark II study was for a power station to produce 100 MW (E), and among the changes were ... 

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