Grid Down, Power Up

Air University Comprehensive Criticism of EPRI 2019 Report on the Power Grid

Air University has provided an excellent comprehensive (40 page) critique of the EPRI Report. Click here for that August 27, 2019 Over the Horizon’s Report, Electromagnetic Pulse Threats to America’s Electric Grid: Counterpoints to Electric Power Research Institute Positions.

In spring 2019, a group of nearly 200 military, government, academic, and private industry experts in various areas of electromagnetic defense gathered for the second Electromagnetic Defense Task Force (EDTF) summit.   

During this time a full analytical and technical review was initiated on the recently released report titled “High-Altitude Electromagnetic Pulse and the Bulk Power System: Potential Impacts and Mitigation Strategies” authored by the Electric Power Research Institute (EPRI). This essay outlines the strengths and weaknesses of the report and aims to generate further discussion among industry, policy makers, military, and academia to ensure the nation is adequately prepared for any potential electromagnetic event.

Executive Summary
The Electric Power Research Institute (EPRI) authored an April 2019 report titled: “High-Altitude Electromagnetic Pulse and the Bulk Power System: Potential Impacts and Mitigation Strategies.” If US Government policymakers rely upon the methodology and conclusions of the EPRI report, effective high-altitude EMP protections will not be implemented, jeopardizing security of the US electric grid and other interdependent infrastructures.

EPRI’s effort draws conclusions about the survivability of the complete electric grid based on a limited assessment of the transmission grid only, omitting attention to the other two main grid sectors: generation and distribution.  Furthermore, EPRI’s assessment of the transmission grid focuses on transformers and digital protective relays and does not take into consideration the vulnerability of other essential electronic systems necessary for transmission grid communication and control.

EPRI used a wide range of optimistic assumptions that downplay the threat of high-altitude EMP from the detonation of nuclear weapons over the United States. Despite having access to defense-conservative Department of Defense threat scenarios, EPRI used alternative Department of Energy scenarios that assume adversaries would detonate nuclear weapons at non-optimal altitudes,when the optimal altitudes are available in the open literature.

For example, rather than modeling an optimal burst height of 75 km for peak E1 field strengths, EPRI chose a non-optimal burst height of 200 km, lowering the peak E1 field strength by approximately 65 percent.  Rather than modeling the optimal burst height of 150 km for peak E3B field strengths, EPRI used an Oak Ridge National Laboratory scenario to assume a burst height of 400 km, significantly lowering the peak E3B field strength.  EPRI used a Los Alamos National Laboratory (LANL) scenario to assume a non-optimal burst height of 200 km, again significantly lowering the maximum E3B field strength. EPRI also assumed latitudes and longitudes for its detonation scenarios that are non-optimal for producing maximum HEMP fields in the Northern Hemisphere.

Additionally, the EPRI report implies that megaton class weapons are needed to cause serious HEMP effects, which is technically incorrect. Multiple high altitude nuclear detonation scenarios will amplify high-altitude EMP effects, but EPRI assumes that adversaries will conduct a HEMP attack with only one nuclear weapon.

EPRI scientists did not use the data and modeling most accurate for assessing high altitude EMP impacts at northern latitudes, including the Soviet high-altitude nuclear tests over Kazakhstan. EPRI had available but chose not to use the HEMP model and waveforms of the Congressional EMP Commission Report of July 2017 which were derived from this real-world Soviet data.[iii] The Soviet data indicates that a peak E3 high-altitude HEMP threat of 85 V/km is possible over continental United States locations. The EPRI report relied instead on a DOE Laboratory (LANL) model that projected the late-time E3 peak field of approximately 35 V/m, which is just 41 percent of the peak field that the EMP Commission recommends for US critical infrastructures.

By avoiding the use of data from declassified Soviet EMP tests on the realistic E3 threat level EPRI was able to minimize numerical estimates of damaged grid equipment, including hard-to-replace high voltage transformers.

EPRI’s optimistic assumptions and scenarios obtained from non-DOD sources allowed them to reach conclusions that do not accurately portray risks to the US electric grid. For example, EPRI’s report states: “Based on the assumptions made in the assessments, it was estimated that approximately 5% of the transmission line terminals in a given interconnection could potentially have a DPR that is damaged or disrupted by the nominal E1 EMP environment, whereas approximately 15% could potentially be affected by the scaled E1 EMP environment.”

The EDTF disputes EPRI’s conclusion that potential loss of 5 percent of transmission line terminals is only a “moderate” concern. Protective relay damage and associated line terminal loss from realistic HEMP scenarios could be far greater, especially with a multiple-bomb EMP attack. Relay malfunction during a HEMP attack would likely cause other electric grid systems to fail, resulting in large-scale cascading blackouts and widespread equipment damage.Notably, E1 effects on protective relays are likely to interrupt substation self-protection processes needed to interrupt E3 current flow through transformers.

“EDTF concludes that the methodology and findings of the EPRI report are inconsistent with the 60+ years of DOD research and experience in understanding EMP environments, system effects, and protection requirements and that the report dangerously and inadequately characterizes impacts on the US electric grid for an EMP event.”


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