«Item 7b Severe Accidents Related Issues Preliminary Monitoring Report Report to the Federal Ministry of Agriculture, Forestry, Environment and Water ...»
7.5.2 Are the staffing/qualification requirements complete i.e. consider all SAM-related parts of the emergency organization (MCR, TSC, operation support, etc.)?
7.5.3 Have appropriate administrative procedures relating to this subject been developed and implemented?
State-of-the-art requirements and practices Appropriately qualified staff should be available at the plant both to participate (or control) in the development/implementation of SAMGs and to ensure effective execution of SAMGs during a severe accident.
The staff involved in the preparation and implementation of the SAMG package should have the expertise and depth of knowledge in plant design and operation as well as in the area of SA phenomenology (including methods/techniques used in SA simulation).
Typically, the team responsible for the execution of SAMG during a severe accident is an integral part of TSC staff (see Section 2.3). The SAMG evaluation group (EG), which is responsible for the evaluation of plant conditions and determination of SAM strategies using SAMGs, is composed of 3 – 4 persons. Typically, the operation support centre (OSC) is used also in the implementation of actions during a SA. No new positions are added to OSC in relation to SAM, however, all staff involved in the execution of SAMGs should receive appropriate training (see Section 3.6.6).
It is desirable that SAMG EG staff, in particular the decision maker, have qualifications and experience in control room operation (senior reactor operator). This would make possible to discuss the actions to be taken under various SAGs and SCGs, the line-ups that have to be made, and the feasibility and execution of repairs in the plant in a proper way (considering the plant capabilities and limitations) independently from the MCR.
Staffing and qualification requirements should be clearly specified and documented for all staff involved in the execution of SAMG. Respective administrative procedures and job descriptions, which reflect the SAM related responsibilities, should be in place.
Current plant status Information on the team involved in the development and implementation of SAMGs at Temelín is limited. It was stated during the Prague workshop that this team included Westinghouse staff and plant staff [Dessars 03]. No detailed information was provided on staffing and qualifications of this team.
Staffing and qualifications of the SAMG Evaluation Group within the TSC have not been discussed in detail during the Prague workshop. Information was given that this group includes 4 persons, namely: the Shift Supervisor, Safety Engineer, Operational Support Engineer, and Intervention Control Engineer [Sỷkora 03 a].
ETE Road Map - Preliminary Monitoring Report – Item 7b: Severe Accidents Related Issues 77 Evaluation The evaluation of SAM-related staffing and qualification aspects was limited due to the lack of information. However, it is well known that Westinghouse has appropriate expertise in the area of SAM and considerable experience in SAMG implementation. Participation of the plant staff ensures good knowledge of the plant. Therefore, it can be expected that this team was properly staffed.
Some concerns can be raised in relation to staffing of SAMG Evaluation Group established within the TSC. It seems that this team is understaffed (see Section 2.4).
The SAM related staffing and qualification aspects should be addressed within an independent review, which would be conducted when the implementation process is finalized (e.g. by IAEA RAMP mission).
3.6.6 SAMGs-Related Training Programme, Training Conduct, and Training Records
VLI No. VLI title / description 7.6.1 Have the training programme and training schedules been defined?
7.6.2 Is the training programme adjusted to the functions of the staff being trained?
7.6.3 Does the training programme for CR operators adequately cover unconventional line-ups actions which may be involved in the implementation of SAMGs?
7.6.4 What type of training is performed? To what extent the training uses practical exercises?
What is the use of simulators? What software tools are available for training?
7.6.5 Does the training address relevant details of SA phenomenology?
7.6.6 Have the staff members, which are involved in SAM, been made familiar with the results of severe accident analysis conducted for the plant?
7.6.7 Is the material, which was prepared to provide basis for SAMP development, used in the training?
7.6.8 Are the emergency response staff members involved in the functional tests of equipment?
7.6.9 Is the training being conducted in accordance to the training programme and schedule?
7.6.10 What SAM-related training records are maintained?
State-of-the-art requirements and practices The staff involved in the development and implementation of SAMGs should receive appropriate training in the field of SA and SAMG. Typically, this training is conducted at external organisations that have the required experience. These staff members become the core of the SAMG development team and later they are an integral part of SAMG EG. This staff would also be involved in the training of other staff involved in SAMG execution (ERO, MCR, OSC, etc.).
Training conducted in relation to SAMGs should include a basic training and refresher training. The training should be adjusted to the functions of the staff being trained. The existence of a well-defined and dedicated training programme is relevant The training programme should be a proper combination of classroom training and exercises.
The classroom training should address all relevant details of SA phenomenology. Presentation of the results of SA analyses for the plant is considered useful way of transferring the required knowledge. The material, which was prepared to provide a basis for SAMP development, can also be used in the training.
The training should include practical exercises. The use of plant specific simulators with severe accident simulation capabilities is desirable. Not all the plants that have implemented 78 ETE Road Map - Preliminary Monitoring Report – Item 7b: Severe Accidents Related Issues SAMGs have simulators that have on-line (real time) capabilities for SA simulation. In these cases the training exercises are based on pre-calculated scenarios that are later reproduced at the training session.
The training programme should adequately cover unconventional line-ups actions that may be involved in the implementation of SAMG strategies during a severe accident. Involving the emergency response staff members in the functional tests of equipment is considered at some plants a good way of enhancing the knowledge of the plant in this context. This issue is in particular applicable to the MCR operators. Since the typical training of operating staff focuses on conventional configurations that are addressed within the DBA, this issue has been found relevant at some plants (e.g. Krško NPP).
The training programme should be documented. The training should be conducted in accordance to the training programme and schedule. The training plans and programmes as well as the execution of training and training results should regularly be evaluated, assessed and approved by the plant management.
The staff training process should be systematically monitored and all relevant training records maintained at the plant. The requirements for storage, maintenance and archiving of trainingrelated documents and records of various types should be specified in the plant administrative procedures that apply to training in general. Typically, the documentation covered by the applicable archive system includes personnel history of training/qualification, training plans, simulator test guides, lectures, and other material used for training. Typically, the responsibility for controlling this documentation and records is given to the training department.
Current plant status No information was provided relating the SAM-related training programme and the staff covered by this training. It was stated during the Prague workshop that such programme is under preparation [Sỷkora 03 b].
Evaluation The SAM related training of Temelín staff is in the stage of preparation and planning. Based on the information presented at the workshop it can be expected that WOG generic training material will be used.
This aspect should be addressed within an independent review, which would be conducted when the implementation process is finalized (e.g. by IAEA RAMP mission).
3.6.7 Feedback from SAMGs-Related Training
VLI No. VLI title / description 7.7.1 Are lessons learned from training and exercises being properly feedback into the SAMGs?
7.7.2 What are the mechanisms/provisions for feedback of lessons from training into the training programme?
7.7.3 Are the responsibilities relating to feedback process clearly assigned to individuals?
State-of-the-art requirements and practices Experience gained during SAMG simulator exercises, which are conducted within the framework of emergency response training, should be incorporated into the training programmes.
Typically, the administrative procedures describing the conduct of simulator training, which should be implemented at the plant, should also be applicable for SAM related training.
ETE Road Map - Preliminary Monitoring Report – Item 7b: Severe Accidents Related Issues 79 These procedures should include explicit corrective action requirements regarding the deficiencies observed during training sessions. They should be addressed and resolved in subsequent training sessions. All identified weaknesses and suggested corrective actions should be documented and analysed to determine areas, which need emphasis in future training.
The responsibilities relating to feedback of this type should be clearly assigned to individuals.
Current plant status Arrangements for feedback of experience from the simulator training into the training programmes and SAMGs were not discussed during the Prague workshop. However, these aspects were addressed in relation to EOPs [Hončarenko 03] (see Section 3.4.1). It is evident that feedback from operational events and from simulator training is systematically made into the EOPs and related training programmes.
Evaluation Considering the existing plant arrangements for feedback in relation to EOPs and experience gained in this area so far, it can be expected that these aspects will be satisfactorily addressed also in relation to SAMGs.
80 ETE Road Map - Preliminary Monitoring Report – Item 7b: Severe Accidents Related Issues
4 ACCIDENT SEQUENCES AND PHENOMENOLOGY
4.1 Accident Analysis Done by PN7 Team As the information on calculations performed by Czech side for Temelín NPP [Duspiva 01, ČEZ 02, Kujal 94, Mlady 01, Sỷkora 01 a, Sỷkora 01 b, SONS 01] was very limited, and no information on verification of these calculations was available, the PN7 team decided to perform a set of calculations for a variety of severe accident scenarios in order to evaluate issues related to severe accident management. Input data used in these calculations were based on the Temelín NPP parameters (when available) and generic WWER 1000 NPP parameters (when the Temelín specific data were not available). It was clear that this approach does not provide results directly applicable to Temelín, but it does allow for identification of potential weak points of the plant and provides a reference framework for a typical WWER 1000 NPP with Temelín features introduced where possible.
Such possibilities existed e.g. in modeling the fuel, which in Temelín is of Western production instead of typical Russian WWER fuel. Also geometrical parameters for Temelín containment and reactor cavity could be taken into account as far as known to the PN7 team. However, a number of important parameters had to be assumed, e.g. the concrete composition or the geometry of passages from the reactor cavity to the containment rooms or the characteristics and locations of hydrogen recombiners.
It was agreed that the analyses would be performed using MELCOR code, since MELCOR was known to be the principal tool used by Czech side in Temelín safety analysis in case of severe accidents and the PN7 team’s analyses were aimed at providing insights into Czech calculations. Some of the scenarios calculated by PN7 team were intended as comparisons to the Czech calculations. The choice of sequences was done taking into account expected Temelín vulnerabilities, judged on the basis of our knowledge of the plant specific PSA and the existing severe accident analyses both of Temelín and other plants of similar vintage.
4.1.1 Temelín Vulnerabilities to Severe Accidents
State-of-the-art requirements and practices The design of NPPs in the 1970s and early 1980s followed the principles of defence in depth (DID) involving multiple barriers placed between the radioactive materials and the environment. The main attention in the design and operation of NPPs at that time was directed to
the first three successive levels of defence of these barriers, namely:
Level 1 Conservative design, providing margins between the planned operating conditions and the failure conditions of the equipment;
Level 2 Control limiting and protection systems, including response to abnormal operation or the indication of system failure;
Level 3 Engineered safety features and accident procedures, to control accidents within the design basis.
Later on, there have been further refinements by including the consideration of external hazards, quality assurance, automation, monitoring and diagnostic tools. Lessons learned from TMI and Chernobyl accidents showed the importance of human factors, man-machine interface, long term effectiveness of containment, need for an effective regulatory body, safety culture, and emergency planning.
The current defence in depth philosophy [IAEA 88, INSAG 3, Frisch 99] gives much consideration to further levels 4 and 5, namely:
ETE Road Map - Preliminary Monitoring Report – Item 7b: Severe Accidents Related Issues 81 Level 4 Complementary measures and accident management to control severe plant conditions, including prevention of accident progression and mitigation of the consequences of severe accidents;
Level 5 Off-site emergency response to mitigate radiological consequences of significant releases of radioactive materials.