He added that the utility would not face fines because the problem was corrected without presenting a public danger.
Under a tax, different utilities would face different challenges.
The utility is facing increasing competition from smaller energy producers and large industrial customers that are generating more of their own power.
Other utilities face questions about the condition of their reactor vessels, the great steel pots that hold the fuel.
S.& P. said that its action was to take into account the tougher times that many utilities would face.
The move by the Pacific Gas illustrates a quandary that many utilities face.
Lilco's problem is the most severe, but other utilities will face the same problems later, industry analysts say.
If tariff revenues remain constant in real terms, utilities face a funding gap of the same magnitude.
Quebec's largest private utility faced the same problem.
Nationwide, utilities face somewhere between $45 billion and $400 billion in stranded costs as they try to gear up for competition, according to various studies.