Thwarting potential threats

Preventing electromagnetic interference from nuclear and other weapons

By Morand Fachot

As concerns about potential risks to power and telecommunication grids from nuclear devices and electromagnetic weapons grow, IEC subcommittee work takes centre stage

Working on high-voltage power lines and pylons is a hazardous occupation Working on high-voltage power lines and pylons is a hazardous occupation

Known phenomena

Cases of electromagnetic fields from solar activity-induced geomagnetic storms disrupting and damaging power grids have been known for a long time. Another type of electromagnetic field known as HEMP (high-altitude electromagnetic pulse) was discovered when nuclear devices were detonated at high altitudes in the 1950s and 1960s. To develop environmental, protection and test standards for commercial equipment that might be exposed to HEMP, in 1992 the IEC created a SC (Subcommittee) under TC 77: Electromagnetic compatibility in 1992. Nowadays its work is proving ever more relevant.

Unwelcome results

In the late 1950s and early 1960s the US and the USSR carried out nuclear tests at high altitudes to study the possibility of using nuclear devices to defeat incoming ballistic missiles and to understand the effects on radio communications. However these HANEs (high-altitude nuclear explosions), besides indiscriminately knocking out the few satellites in orbit in 1962, had unexpected consequences on the ground by disrupting and even damaging a few telecommunication and electric installations, including portions of the power and communications infrastructures. While these effects were not widespread, it is clear that the electromagnetic sensitivities of the electronics controlling today’s infrastructures are much higher than they were 50 years ago.

Different parameters for the US and Soviet HANEs (altitudes, weapons’ yields and locations –- over water in the Pacific Ocean for US tests, over land for Soviet tests) meant different results.

HEMP from the July 1962 Starfish US test (400 km altitude, 1,4 megaton device) caused burglar alarms and air raid sirens, street lights and telecom systems to malfunction or fail in Hawaii, some 1 400 km away from the burst.

HEMP from several October 1962 Soviet HANEs (300 km, 150 km, and 60 km altitudes, each with a 300 kiloton device) carried out over Kazakhstan in what was then the USSR, fused at least 570 km of overhead telephone lines, overloaded a 1 000 km shallow-buried shielded communications cable and damaged power line insulators, according to information made public by former Soviet scientists in 1994 during the EUROEM 1994 Conference in Bordeaux.

IEC involvement

IEC SC 77C Chairman Dr William Radasky traces back the IEC's involvement in the field to 1989 (as a Working Group of TC 77) when it began the development of environment, protection and test standards for commercial equipment that might be exposed to HEMP.

When the pace of the work on HEMP accelerated in 1992, he says, it was assigned to the newly created IEC SC 77C: Immunity to High Altitude Nuclear Electromagnetic Pulse (HEMP). In 1999 the National Committees in SC 77C decided that it was important to extend this work to include high power electromagnetic transients created by electromagnetic weapons producing IEMI (intentional electromagnetic interference), based on concerns raised by URSI (International Union of Radio Science). The new (and current title) of SC 77C is: High power transient phenomena.

SC 77C's scope is to prepare "standardization in the field of electromagnetic compatibility to protect civilian equipment, systems and installations from threats by man-made high power transient phenomena including the electromagnetic fields produced by nuclear detonations at high altitude."

SC 77C has 18 participating member nations and 15 observing member nations that prepare publications within the IEC 61000 series, many of which are basic standards that need to be applied to specific products and industries.

The 20 publications available thus far in the series are divided into 5 major parts covering: general, environment, testing and measurement techniques, installation and mitigation guidelines, and generic standards. Each part is further subdivided into several subparts or sections, and these are published as International Standards, Technical Specifications or Technical Reports.

Radasky says that the basic work covering both HEMP and electromagnetic weapons that have the capability to produce IEMI is now complete. He adds that future work is planned that will use the existing basic publications as a “tool box” to solve more complex problems – for example, dealing with the distributed civil infrastructure. In a further example, the Chairman of IEC TC 13 recently asked for support from SC 77C to help develop an immunity test method that would allow Smart Meters (electronics based) to be protected from attacks from stun guns.

Governments, other organizations relying on SC 77C work

As a growing number of countries or non-state actors may gain access to nuclear weapons, and criminals may obtain the ability to inflict IEMI (which is a much more accessible technology), IEC SC 77C work is seen as absolutely essential by governments and organizations that seek to protect infrastructures from high power EM threats.

Recent confirmation of this can be found in evidence, documents and references provided to the UK House of Commons Defence Committee by IEC SC 77C Chairman Radasky and Secretary Dr Richard Hoad, which figure prominently in the Committee's 10th Report of Session 2010–12: "Developing Threats: Electro-Magnetic Pulses (EMP)". In addition, earlier work by the US Congressional EMP Commission included contributions from IEC SC 77C. Their work is published in two reports available at

As regards standardization and other organizations, IEC SC 77C publications have been adapted in recent years to the needs of the telecommunications industry by the ITU (International Telecommunication Union) in ITU T Recommendations K.78, and K.81, and to the needs of the international power industry in Cigré (International Council on Large Electric Systems) WG C4.206 where work is underway.

SC 77C International Standards, Technical Specifications and Technical Reports are also extensively referenced in countless specialist reports and documents

Working on high-voltage power lines and pylons is a hazardous occupation Working on high-voltage power lines and pylons is a hazardous occupation
...on power installations... ...on power installations... powerful solar storms (Photo: NASA) powerful solar storms (Photo: NASA)