There are several simple (loosely defined) ways to accomplish this without a bulky reactor plant. Use the heat from radioactive decay to create power. It eliminates the need for the reactor vessel and a cooling structure. I understand this is not a nuclear reactor, but it is a way a home consumer could access nuclear power.
Advanced Stirling Radioisotope Generator
An Advanced Stirling Radioisotope Generator (ASRG) is a radioisotope power system developed at NASA's Glenn Research Center. It's based on an idea of creating power from the heat of radioactive decay from plutonium.
It uses a Stirling power conversion technology to convert the radioactive-decay heat into electricity for use on spacecraft.
A Stirling engine is a closed-cycle regenerative heat engine with a permanently gaseous working fluid. Closed-cycle, in this context, means a thermodynamic system in which the working fluid is permanently contained within the system, and regenerative describes the use of a specific type of internal heat exchanger and thermal store, known as the regenerator. The inclusion of a regenerator differentiates the Stirling engine from other closed cycle hot air engines.
The positive is this a pretty simple mechanical system. The drawback is that this unit will produce 130 watts of power from 1.2 kilos of plutonium-238-dioxide. To meet your power goals, you would need to run several in series, or perhaps in your world, the technical limitations were overcome and one unit will produce the required power.
For more information, check out: https://en.wikipedia.org/wiki/Advanced_Stirling_radioisotope_generator
Radioisotope thermoelectric generator
Another existing power source is the Radioisotope thermoelectric generator.
The positives are this can be created with no moving parts. The drawback is a low power yield.
A Thermovoltaic generator captures the light given off the thermal source and translates that into power. The positives are that thermovoltaics provide consistent and reliable power without large amounts of fuel. The drawback is that they are not very efficient. If your power source was in a sphere of thermal-voltaic cells, you could run them in series to produce the energy you need. Perhaps in your world, there's a more efficient source of thermovoltaic cells, which could produce the 8,000 watts of desired power.