- Legal Principles
- Assessment Methods for Containers for Intermediate and Permanent Storage
- The Safety Engineering Assessment of Containers for Long-term Intermediate Storage of Irradiated Nuclear Fuel Elements or Highly Radioactive
- The Nuclear Supervisory Process for Approved Intermediate Storages for Containers
- The Safety Engineering Assessment of Containers for the Permanent Storage of Weakly Active or Medium Active Solid or Solidified, Non-heat-generating Radioactive Waste
- Enclosed Radioactive Substances
The safety engineering assessment of containers for long-term intermediate storage of irradiated nuclear fuel elements or highly radioactive waste from reprocessing is carried out in compliance with §6 Atomgesetz (Atomic Energy Act) (AtG): "Approval for the storage of nuclear fuels“. According to Section 6(1) AtG, this refers to storage outside of safekeeping by the state.
According to Section 6(2) of the AtG, "the approval is to be granted if there is a need for such storage“, and according to Section 6(2)2 "measures against damage have been taken by means of storage in compliance with the state of the art of technology“.
According to Section 23(1)4 of the AtG, "the Federal Office for Radiation Protection (BfS) is responsible for the approval of the storage of nuclear fuels outside of the scope of safekeeping by the state“.
The assessment of containers with regard to safety-engineering is performed by the BAM when the BAM is consulted as a specialist by the BfS in compliance with Section 20 AtG, see 2.1.
Based on the storage approval for intermediate container storage, issued by the BfS in compliance with Section 6 AtG, BAM has been commissioned by the nuclear supervisory authorities responsible for the approved plants (generally the environmental ministries of the states) to perform safety-engineering assessments of container-specific aspects compare 2.2. Here an important aspect is the monitoring of production-accompanying controls during the manufacture of storage containers.
In the field of type testing for containers/packagings to be used for the permanent storage of radioactive waste, the BAM has, in compliance with Section 9a(3) AtG in conjunction with Section 23(1)2 AtG been commissioned by the BfS to work for the KONRAD mine facility compare 2.3.
The Atomic Energy Act (AtG) as well as other current legislation can be viewed in whole under The Federal Office for Radiation Protection (BfS) "Laws and Regulations“.
Assessment Methods for Containers for Intermediate and Permanent Storage
The Safety Engineering Assessment of Containers for Long-term Intermediate Storage of Irradiated Nuclear Fuel Elements or Highly Radioactive
The safety engineering assessment of containers for long-term intermediate storage of irradiated nuclear fuel elements or highly radioactive, glass-encapsulated waste from reprocessing includes examining the proof of safety that must be forwarded by he respective applicant.
The focal points for assessment include the following issues:
- Long-term stability of the container and all of its components (particularly the metallic sealing systems) und storage-specific operating conditions, such as temperature conditions, humidity in the store house, radiation intensity, mechanical loads.
- Assurance of tight enclosure of the radioactive content under the mechanical and thermal loads prevalent in the operation for which it was designed.
- Safety engineering assessment of the effects of a presumed dropping of a container while it is being handled on the store house (design incident).
- Assessment, determination and monitoring of the necessary quality assurance measures for manufacturing the container and operating it. This includes material and component specifications, regulations for testing, working and erecting as well as servicing instructions e.g. for container dispatching after loading, for storing containers and for monitoring leak tightness of containers in storage.
- Safety-engineering assessment of container related effects (particularly on integrity and leak tightness) of incident events with probability of their occurrence, which lie within the residual-risk range, e.g. the accidental crash of a fast-flying military aircraft.
The examination of application documents is performed with regard to completeness and factual correctness on the basis of the state of the art of science and technology, as required in the German Atomic Energy Act e.g. in Section 6 (2) 2. For this purpose the evidences presented are individually assessed using suitable testing methods to determine their correctness and the statements that they make relevant to safety engineering.
- Classic test methods used include:
- recalculation and examination of the underlying boundary conditions,
- focused mathematical comparison with other calculatory methods or models (e.g. with analytical approximation methods or suitable finite-element calculations),
- performance of or referral to the results of experimental investigations,
- use of comparative considerations, transferability analyses and/or model considerations.
Where relevant deficiencies are found during the examination of the documents forwarded by the applicant, the latter is requested to correct or supplement these as required.
The results of the safety-engineering examination and assessment are compiled in a comprehensive Expert Opinion and Appraisal prepared by BAM. Where applicable, these contain corresponding remarks and suggested conditions with respect to additional measures considered necessary for ensuring the safe operation of the container.
Die Expert Opinions and Appraisals provided by the BAM serve to provide the responsible authority with a decision basis with respect to the application of nuclear regulatory approvals. An overview of issued storage approvals as well as current examples concerning the approval of so-called decentralized intermediate storages for an intermediate storage period of up to 40 years for CASTOR containers at the nuclear power plant sites can be found on the homepage of the The Federal Office for Radiation Protection (BfS)..
The Nuclear Supervisory Process for Approved Intermediate Storages for Containers
Within the framework of the nuclear supervisory process for approved intermediate storages for containers , the BAM is concerned with the safety engineering assessment of container-specific aspects in conjunction with container production, dispatching of containers after filling, and their deposition and/or storage in the intermediate storage facility.
In the production of containers, the BAM or a specialist appointed by her, performs the specified production-line examinations, similarly to the way in which it is already being performed in the area of traffic regulations for transport and storage containers by the BAM, which is the responsible authority in compliance with the „Technische Richtlinie über Maßnahmen zur Quali-tätssicherung (QM) und -überwachung (QÜ) für Verpackungen zur Beförderung radioaktiver Stoffe“ (TRV 006 - Engineering guideline for measures for quality assurance and monitoring for packagings for the transport of radioactive substances). Depending on the results of these tests, so-called Konformitätsbescheinigungen (certificates of conformity) are issued; these certificates confirm for every single container produced in series that all required quality assurance measures have been properly implemented, and that all specified requirements with respect to their suitability as intermediate storage containers have been proven.
When intermediate storage containers are loaded and dispatched in nuclear power plants and nuclear reprocessing plants (e.g. at COGEMA in La Hague (F)), specialists from the BAM are generally consulted when these processes are being performed the first time or when considerable changes are made to important process steps. Here, particular content focus is placed on the assembly processes used for cover-sealing systems for containers including the helium sealing test, as well as drying and the residual moisture test for containers that are loaded with nuclear fuel elements under water in the cooling pit of a nuclear power plant.
In conjunction with the deposit of loaded containers into the intermediate storage facility, it is required to assess the concluding assembly work for the secondary so-called secondary cover sealing system as well as the container monitoring system with respect to their adherence to the seal tightness requirements. Here too BAM specialists are generally consulted when these are performed the first time or when there are considerable changes. Furthermore, this is also done when there is any conspicuousness during storage operation, and this requires an additional safety engineering assessment as commissioned by the responsible supervisory authority.
The tests performed by the BAM within the framework of the nuclear energy supervision process, during which the same methods are used as presented in section 2.1, are documented in expertise statements and/or in the above mentioned certificates of conformity which, here too, serve the respective responsible nuclear energy supervisory authority as a basis for decision-making.
The Safety Engineering Assessment of Containers for the Permanent Storage of Weakly Active or Medium Active Solid or Solidified, Non-heat-generating Radioactive Waste
The safety-engineering assessment of containers for the permanent storage of weakly active or medium active solid or solidified, non-heat-generating radioactive waste encompasses examining the safety evidence to be provided by the respective applicant, with due consideration being given to the specified permanent storage requirements. Currently the requirements for the above waste types from medicine, research and the operation of nuclear facilities are for the Konrad final disposal site. These have been defined in the „Planfeststellungsbeschluss für die Errichtung und den Betrieb des Bergwerkes Konrad in (Planning permission decision for the establishment and operation of the Konrad mine in Salzgitter) dated 22 May 2002. For further information, please consult e.g.
Federal Office for Radiation Protection
Federal Environment Ministry
Ministry for Environment Lower Saxony
Various cylindrical and cubic container types have been defined for permanent storage; depending on the respective type of waste and their activity inventory, these must meet certain safety engineering requirements. These requirements embrace general design specifications such as geometry and masses, corrosion protection requirements, requirements concerning mechanical design with respect to normal operating conditions (e.g. handling) and incident conditions (e.g. falling container) and thermal design with respect to normal operating conditions and incident conditions (e.g. fire).
To provide evidence that such containers meet these requirements, different type tests have been specified (e.g. stacking test, lifting test, fall test), and it is the respective applicant’s responsibility to provide evidence that these have been properly performed and interpreted. Finally, evidence must be provided to show that a suitable quality assurance program has been put in place for the series production of containers.
An English-language overview of BAM activities in this field.
Testing and assessing of the safety evidence forwarded to the BAM by the applicant are performed in compliance with the test methodology presented in Section 2.1. Depending on the result of this examination, the BAM will issue a BAM test certificate, which serves the Federal Office for Radiation Protection as a basis for confirming the suitability of a container type for final storage purposes.
Enclosed Radioactive Substances
Methods for type approval
Within the scope of its type-approval work for apparatuses and devices into which other radioactive materials have been introduced, BAM complies with Section 25 of the German Radiation Protection Ordinance "Verfahren der Bauartprüfung" (methods of type testing) to assess the enclosure of the introduced radioactive materials with respect to design, choice of materials used and leak-tightness as well as the quality assurance used during production and operation.
The basis for the appraisal is the suggestion put forward by the Commission on Radiological Protection:
- Suggestion for requirements for type-testing devices into which radioactive materials are introduced
Report by the Commission on Radiological Protection
177th Meeting of the Commission on Radiological Protection
Requirements for type-testing
Recurring leak test
BAM assesses test schedules for the recurring leak tests required by Section 66 of the German Radiation Protection Ordinance "Wartung, Überprüfung und Dichtheitsprüfung" (maintenance, examination and leak test), paragraph 4, for enclosed radioactive materials.
The basis for the BAM's responsibility is the directive concerning leak tests performed on enclosed radioactive materials:
- Suggestion for a revised version of the directive concerning leak tests performed on enclosed radioactive materials
Report by the Commission on Radiological Protection
179th Meeting of the Commission on Radiological Protection
Suggestion for a revised version