Satellite surveys suggest that the flood originated in the valley of the stream Raunthi, which is the first major confluence upstream of Reni village on the Rishi Ganga. This puts the origin of the flood at a tributary valley that's outside of any path the secret Nanda Devi expedition would have taken.
The rumour supposed that perhaps the plutonium capsules (which continue to generate heat by radioactive decay, since that's their purpose) had melted through ice and the meltwater deluged downstream. It's not improbable that this may happen someday, or that their presence perhaps already contributes meltwater into the Rishi Ganga, but the location of their demise is not the tributary valley where the February 2021 flood appears to have originated.
Part of the confusion is that the origin point of the flood was not immediately known, only that it came from somewhere within the Nanda Devi Sanctuary, a large nature reserve area that shares the name with the famous mountain contained within.
The rumour supposed that perhaps the plutonium capsules (which continue to generate heat by radioactive decay, since that's their purpose) had melted through ice and the meltwater deluged downstream. It's not improbable that this may happen someday, or that their presence perhaps already contributes meltwater into the Rishi Ganga, but the location of their demise is not the tributary valley where the February 2021 flood appears to have originated.
Part of the confusion is that the origin point of the flood was not immediately known, only that it came from somewhere within the Nanda Devi Sanctuary, a large nature reserve area that shares the name with the famous mountain contained within.