The Lost Nuclear Spying Device of Nanda Devi
During a trek - a friend of mine told me about a book The Nanda Devi Mystery: How India and America Lost a Nuclear Device I had to go down that rabbit hole. The mountain that is keeping a secret…
Here’s the juicy bit -
In the mid-1960s, the Cold War between the U.S. and USSR were about stockpiling nukes, while China’s first atomic test in 1964 added a volatile new concern. India, still reeling from the 1962 Sino-Indian war, feared a nuclear-armed neighbor across a disputed, poorly mapped frontier. Washington wanted eyes on China’s Lop Nur tests but couldn’t overfly undetected. The solution: mountain espionage—placing long-range sensors on Himalayan peaks inside India. For Delhi, cooperating with the CIA promised early warning and leverage; for Washington, it offered a stable platform above Tibet. The Nanda Devi mission emerged from that calculus.
In October 1965, a joint CIA–IB team carried a compact, radioisotope thermoelectric generator (RTG) up Nanda Devi—meant to power a listening post pointed at China’s new nuclear test range. A brutal storm hit. The team cached the unit near ~24,000 ft and retreated. When they returned in spring 1966, the device was gone. The story stayed buried until 1978, when it surfaced in the press and inside India’s Parliament. (The Washington Post)
A year after Nanda Devi, climbers installed a second unit on Nanda Kot. It worked briefly, then failed; a check team later found a melted cavity around the hot generator—consistent with what an active Pu-238 heat source can do in ice. (This episode is documented in mountaineer accounts and long-form reporting.) (WIRED)
Why it got me interested? Nanda Devi glaciers feeds River Ganga. And The Gangetic Belt caters to 500M+ people. Melt here becomes the Rishiganga → Dhauliganga → Alaknanda, which meets the Bhagirathi at Devprayag to become the Ganga—a basin that underwrites the livelihoods of over 500 million people through agriculture, fishing, and tourism. If that missing unit is still intact and entombed, the risk is low. If it isn’t, the downstream consequences sit in that uncomfortable quadrant: low probability, very high impact!
What, exactly, was carried up the mountain?
Not a bomb. An RTG—a device that turns the heat from a decaying radioisotope into electricity. In the 1960s, the U.S. used plutonium-238 (Pu-238) for this: a strong alpha emitter with an ~88-year half-life that gives off steady heat. (NASA still uses Pu-238 to power deep-space missions.) The danger isn’t external exposure; it’s if particles are inhaled or ingested—which is why capsule integrity is everything. (The Department of Energy's Energy.gov)
What is firmly on the record
The operation & loss (1965–66): Documented by the Washington Post (1978) and referenced in Indian parliamentary records. The device was cached during a storm and later found missing. (The Washington Post)
The Nanda Kot follow-up (1967): A second unit installed on Nanda Kot functioned briefly; subsequent accounts describe a heat-melt cavity in the ice on inspection. (Useful narrative synthesis in later reporting/interviews.) (WIRED)
Public acknowledgement (1978): Prime Minister Morarji Desai addressed the issue in Parliament; monitoring of the area was discussed/urged in debates. (Rajya Sabha PDFs are available.) (Rajya Sabha Debates)
Chamoli 2021 floods wasn’t radiological: The catastrophic 7 Feb 2021 event was a rock/ice avalanche that transformed into a debris flow, per a paper in Science and aligned technical summaries. Not a radiation incident. (Science)
What remains unknown (publicly)
Location: No open record confirms a recovery. The simplest scenario is still “buried somewhere on Nanda Devi.” (The Washington Post)
Capsule integrity: We don’t have a declassified, technical condition report of the lost unit—only the knowledge of how these systems are designed and how Pu-238 behaves. (The Department of Energy's Energy.gov)
Monitoring data: Parliament debated the issue in 1978, but there isn’t a publicly maintained, time-series dataset of alpha activity and Pu isotopes for the Rishiganga–Dhauliganga–Alaknanda–Bhagirathi chain. (Rajya Sabha Debates)
So… is there a downstream hazard?
There is no confirmed downstream radiological hazard in the public record. But risk isn’t binary; it’s a product of hazard × exposure × vulnerability.
If the unit is intact & entombed: Alpha particles don’t travel far; intact encapsulation + burial = minimal exposure, hence minimal risk.
If the capsule degraded locally: The right place to start (according to AI intelligence) detect it is suspended sediment and sediment cores near the headwaters.
If a failure released fine particles that moved with melt & debris: That’s the low-probability, very high-impact path—where hydropower reservoirs, river intakes, and flood-transported fines matter. Chamoli 2021 shows how fast mass flows can move down these valleys—even though the cause in that case was geologic, not radiological.
What good policy looks like (not panic—planning)
1) Monitoring & transparency
Mandate annual, independent radiological screening of:
Water,
Suspended sediment, and
Reservoir/barrage sediment cores
Cover the Rishiganga → Dhauliganga → Alaknanda → Bhagirathi → Ganga chain and publish raw data + methods. Ground truth beats rumour. (The case exists; Parliament put this on record in 1978.) (Rajya Sabha Debates)
2) Locate-or-leave strategy
Commission a modern assessment using airborne & ground geophysics (GPR, magnetometry, neutron/gamma surveys) with glacier/rock-mechanics models to map a probable burial zone, then compare retrieval vs. monitored entombment in a transparent risk–benefit framework. (Technology has moved a long way since the 1960s.) (CIA)
3) Triggered response & drills
Define thresholds (counts, isotope IDs) that automatically trigger:
upstream intake shutdowns,
public advisories, and
playbooks for hydropower operators and district authorities.
Run table-top and field drills with external observers (IAEA/WHO-aligned methods). The Chamoli 2021 papers are reminders that speed and coordination matter in these valleys. (Science)
Primary & technical sources (open links)
Washington Post (Apr 12, 1978): “CIA Put Nuclear Spy Devices in Himalayas.” (The Washington Post)
Rajya Sabha Debates (May 18, 1978): “Reference to Nuclear Device on Nanda Devi” (PDF). (Rajya Sabha Debates)
Lok Sabha record (Apr 17, 1978): Prime Minister Morarji Desai—item on the reported planting (index entry). (eparlib.sansad.in)
Science (2021): Shugar et al., “A massive rock and ice avalanche caused the 2021 disaster at Chamoli, Indian Himalaya.” (Science)
PubMed / USGS entries summarizing the Chamoli paper and findings. (PubMed)
DOE Pu-238 Fact Sheet (overview of RTGs and Pu-238). (The Department of Energy's Energy.gov)
NASA RPS: About Pu-238 + RTG factsheets. (NASA Science)
Background narrative: Wired feature on the CIA mission (useful interviews and chronology). (WIRED)
The Himalayas deserve better conservation! If the nuclear device stays sealed and buried, great—prove it every year with measurements anyone can audit. If it isn’t, we’ll be glad we prepared…
@the.photoguy
Rajarshi Mitra
