Just as a starting point, the Wikipedia article for the Loongson processor family points to this paper, which has a few more cool details.
2.2 Loongson X-CPU radiation hardening by design
The paper titled “Loongson X-CPU radiation hardening by design” introduces the design
of a radiation hardened processor for space applications. Radiation
hardening can be achieved by adjusting the manufacturing process;
however, this approach is prohibitively expensive. Radiation hardening
by design (RHBD) [18,19] is the most widely used radiation hardening
method that does not require adjustments to the manufacturing process.
The authors discuss the RDHB method from multiple aspects, including
circular-shape gate layout, guard-ring protect, time and space triple
modular redundancy, dual interlocked storage cells, and error
detection and correction coding, and apply all of them to the
anti-radiation design of Loongson X-CPU. The Loongson X-CPU is a
highly integrated, high-performance SoC based on the dual-issue,
32-bit Loongson GS232 CPU core. It was fabricated with 180 nm CMOS
The chip operates at 100 MHz and contains a CPU core with
separate instruction and data caches, an SDRAM/SRAM controller, a PCI
controller, an SPI controller, an interrupt controller, two UARTs, an
I2C and WDT interfaces. The chip was tested up to a total dose of 300
krad (Si), and it yielded an SEU error rate better than 1.90362 ×
10^−5/device/day. The results demonstrate that the chip can adapt to
complex space environments and meet the demands of complicated
applications. On March 30, 2015, China launched a new-generation
manmade satellite into space for its BeiDou global navigation and
positioning network. In this satellite, Loongson X-CPUs are used to
perform tasks such as controlling, communication and data processing.
I haven't found a source for the referenced paper, "Loongson X-CPU radiation hardening by design".