They single-handedly cost the taxpayers and ratepayers of California several billion dollars in "stranded costs".
To the best of my knowledge, they were a local, homegrown group with no outside funding, although they were in cahoots with groups like the "Government Accountability Project".
I could be wrong, but it doesn't take much money to file all these objections. The system is set up to make it easy for intervenors.
Basically the cost of paper, an envelope, and a postage stamp. Petitions for leave to intervene with the NRC may involve a filing fee, but its pretty mimimal.
The hell of it is, when such things are filed, at least with the NRC, they are legally obligated to at least consider them and issue a finding. That takes staff time. Since the NRC is 100% funded by licensing fees (no net taxpayer dollars expended), the costs for dealing with allegations filed by intervenors filed against licensees or applicants is paid for by...licensees and applicants. You couldn't do a better job if you tried of designing a system tailor-made for abuse.