A former Sellafield worker is appealing against an employment tribunal which dismissed claims her contract was terminated unfairly.
Consultant Alison McDermott made allegations of harassment and bullying against the nuclear site but a judge ruled that she could not qualify as a whistleblower.
She has lodged an appeal on the basis that key evidence wasn't taken into account during her hearing.
Ms McDermott, who was paid £1,500 a day for her services, had her contract terminated in October 2018 after she wrote a report which was highly critical of the HR department.
Ms McDermott said the report also described a "legacy of cover-up" around multiple allegations.
However, the Sellafield nuclear plant HR director who was accused of terminating Ms McDermott contract because she was a whistleblower denied the accusations, and said she made the decision because of "mistrust".
Sellafield has confirmed that it won't comment on the case for legal reasons.