Annual Report 2020

Waste management, interim and final storage (back end)

GRI 103: Management approach (103-1, 103-2, 103-3)


Power production from nuclear energy produces radioactive waste. As a shareholder in KKG and KKL, Alpiq takes on a part of the annual costs in proportion to its share; this obviously includes the costs of decommissioning and dismantling. At both plants, protecting the population, employees and environment from ionising radiation takes the highest priority. This includes the safe handling of radioactive waste.

Management approach

When handling radioactive waste in nuclear power plants, a distinction is made between operational waste and spent fuel elements and waste from reprocessing. The safety and health of employees is ensured through the consistent implementation of the appropriate guidelines: Guideline ENSI-G15 defines the radiation protection limit values that apply in Switzerland to employees and to the population surrounding the nuclear power plant. These are monitored in accordance with guideline ENSI-B09 and reported to ENSI in accordance with guideline ENSI-B03.

Operational waste (IAEA classification: low and intermediate-level waste, LLW and ILW):

Radioactive operational waste (raw waste) is generated in a nuclear power plant on a regular basis from the water cleaning systems and from exhaust air cleaning. Other waste comes from replacing components during maintenance, modification or retrofitting work and the consumables used in these processes.

The radioactive waste is collected, conditioned on a campaign basis and then placed into intermediate storage. The unconditioned waste present in a nuclear power plant is stored in specified rooms in the controlled zone.

The following conditioning processes are used at a nuclear power plant: Encapsulation of resins in polystyrene, cementing of sludge or bonding in bitumen. Combustible and fusible raw waste or exhaust air filters are provided for treatment in the plasma plant at the central intermediate storage facility (Zwilag) in Würenlingen. For all processes in Switzerland, the type approvals required in accordance with the Swiss Nuclear Energy Ordinance (KEV) and guideline ENSI-B05 are available. The conditioned waste containers are routinely placed into storage at the plant’s own intermediate storage facility or at the Zwilag.

The radioactive waste from Swiss nuclear power plants is logged in an electronic accounting system used by all Swiss nuclear power plants, so that information about quantity, storage location and radiological properties is available at all times.

A key element in the minimization of radioactive waste is the inactive clearance measurement of materials from the controlled zone.

Fuel elements and waste from reprocessing (IAEA classification: high-level waste, HLW):

After final unloading from the reactor core, spent fuel elements are stored for several years in the plant’s own wet storage pool to cool down. During this time, the thermal output subsides significantly, so that the fuel elements can subsequently be placed in optimal storage in intermediate storage containers. These storage containers are constructed according to international standards and licensed and stored in Switzerland in accordance with ENSI guidelines ENSI-G04 and -G05. The currently valid guideline HSK-R-29 will soon be replaced by the guideline ENSI-G04. The loaded containers are transported to the Zwilag where they are placed into storage. In the reporting year, the following transportation took place from KKG and KKL to the Zwilag.

Number of transportation operations of radioactive materials from the nuclear power plants to the Zwilag.

Numer of transportation operations


HLW / fuel elements

Gösgen nuclear power plant



Leibstadt nuclear power plant



The Swiss guidelines on the transportation of radioactive materials on road and rail are based, among others, on the international regulations on the carriage of dangerous goods by road (ADR) or by rail (COTIF). For all modes of transport, the IAEA recommendations for safe transport of radioactive material (IAEA SSR-6) apply.

The process of handling water and wastewater is defined in specific terms for each nuclear power plant in rules of delivery that are checked and approved by ENSI. The delivery data for 2019 and 2020 is publicly available from ENSI (ANPA-EMI data).


To ensure consistency with the data in the ENSI Oversight Report 2019, the following data refers to the calendar year 2019. The data for the calendar year 2020 will not be published by ENSI until mid-2021.

In 2019, all radiation protection limit values were observed, guaranteeing the safety and health of employees. The objective of safe handling of radioactive waste was achieved.

The waste generated in KKG and KKL is listed in the following table. In 2019, no long-lived intermediate-level waste (ILW) or high-level waste (HLW) from the reprocessing of spent fuel elements was transported back into Switzerland. All obligations relating to the return of waste from reprocessing have been fulfilled.

Nuclear data relating to the back end in 2019 (this data refers to the total quantity and is not scaled according to the share proportion).


LLW / ILW unconditioned in m 3

LLW / ILW conditioned in m 3

ILW in m 3

HLW in m 3

Unloaded fuel in t

Fuel transported to Zwilag in t

Gösgen nuclear power plant







Leibstadt nuclear power plant







No Swiss nuclear power plant in which Alpiq holds a share causes significant heating of a body of water. Both KKG and KKL are cooled by cooling towers and not by the adjacent rivers. The water in the cooling towers comes from the rivers and the reintroduction of cooling water does introduce some heat but not significantly. In periods of hot summer causing very high river temperatures, the nuclear power plants reduce their power to remain under the regulatory thresholds.