Use of passive auto recombiners (PARs) started over 30 years ago on a large scale and has been state of the art for more than two decades now: https://inis.iaea

Use of passive auto recombiners (PARs) started over 30 years ago on a large scale and has been state of the art for more than two decades now: https://inis.iaea.org/collection/NCLCollectionStore/_Public/33/020/33020098.pdf https://inis.iaea.org/collection/NCLCollectionStore/_Public/... However, many operators didn't want to spend the money, which is why Fukushima didn't have a PAR at the time of the accident. The problem with Fukushima is that I fear we do not learn from accidents. Otherwise, Fukushima wouldn't even have been in operation at the time of the accident as it is an old reactor model well past its design life. The location was, as we have known before the accident, poorly chosen. Safety measures, such as PARs, seawalls and properly redundant power supplies were skipped or badly implemented due to the cost involved. All this was known before the accident, however neither the operator nor the national oversight took any action before it was too late.