The current project covered some of the assistance provided to the State Nuclear Regulatory Committee of Ukraine needed for the licensing activity related to TACIS/NSA financed Decommissioning Facilities at Chernobyl NPP. In particular, the project was designed to deal with the necessary technical evaluation needed for the licensing of design and construction of a Liquid Radwaste Treatment Plant.
The work was performed in parallel by an EU TSO on the one side (GRS for Riskaudit), using Western European approach and practice, and an Ukrainian TSO (State Scientific and Technical Center - SSTC) on the other side using existing Ukrainian practice.The task of Riskaudit (project contractor) was to assess the "EU- TSO" analysis, to guide the Ukrainian evaluation, and finally, as far as possible, to harmonise the two sets of conclusions and recommendations.
A quality control by a second EU TSO (ANPA, Italy) of results achieved by GRS have been performed to guarantee acceptable quality level of the evaluation report.
The main objective of the UK/TS/20 project was to provide assistance and support to the SNRCU in licensing of design and construction phases for the Liquid Radwaste Treatment Plant (LRTP) to be built at the Chernobyl NPP site.
The specific objectives were to formulate relevant recommendations to SNRCU based on the review of the following document supplied by the applicant for license.
For the design phase:
- The first stage reconciliation programme,
- The first conceptual design information with supporting documentation,
- The corresponding QA programme,
- The proposed PSAR content, the list of initiating events to be considered, the list of studies to be performed.
For the construction phase:
- The draft Preliminary Safety Analysis Report (PSAR) and associated documents delivered by the Applicant in the framework of the Construction Licence process, including also siting aspects, decommissioning plan and environmental impact assessment statements.
These reports were evaluated in order to verify that the technical options taken into account for the design of the LRTP can fulfil the nuclear safety and radiological protection objectives or requirements.
The evaluation process included several steps. In the first step Riskaudit and SSTC identified and commented issues of safety relevance in each chapter of the draft PSAR, which needed further clarification. These comments were transmitted through SNRCU to the Applicant with the request for resolution and written answers. In the second step Riskaudit and SSTC evaluated a revised second version of the PSAR that the Applicant submitted to SNRCU to get a construction license. The results of this evaluation were reported in several documents (see below)
As a result of the evaluation the following technical reports were produced and provided to the beneficiary SNRCU:
- Preliminary comments on the Draft Liquid Radwaste Treatment Plant(LRTP) PSAR content
- Comments on the Draft LRTP PSAR content,
- Report on the evaluation of draft information for the construction licence of the LRTP;
- Report on the evaluation of draft information for the construction licence of the LRTP, prepared by SSTC;
- Evaluation of the Preliminary Safety Analysis Report (PSAR Rev. 2) and the Environmental Impact Assessment Report (EIAR) for the Liquid Radwaste Treatment Plant (LRTP), Safety Evaluation Report and Recommendations for Improvement of the Safety Demonstration;
- Conclusion of State Expert Assessment on Nuclear and Radiation Safety. Preliminary Safety Analysis Report for Liquid Radwaste Treatment Facility of Chernobyl NPP;
- Common Riskaudit and SSTC Recommendations for Improvement of the Safety Demonstration after Evaluation of the Preliminary Safety Analysis Report (PSAR Rev. 2) for the Liquid Radwaste Treatment Plant (LRTP) and the Environmental Impact Assessment Report (EIAR);
- Common Riskaudit and SSTC Expert Assessment on the Chernobyl NPP Technical Note C1/01/002 "Liquid Radwaste Treatment Plant -Radiological Dose Assessment of the Intervention Personnel".
As a result of the evaluation the following recommendations were done and provided to the beneficiary SNRCU:
The description of radiological protection requirements and measures for the workers during the construction of the LRTP does not present sufficiently the protection of the workers against doses due to inhalation and the potential need for protection measures (e.g., requirement for measures to avoid dust and to protect worker against airborne a-activity during the construction). Dose limits (0,5 ~Sv/h) should be substantiated more correctly in the PSAR considering all sources of ionising radiation and waste with impact on the personnel. The results of the dose assessment for normal operation have to be reviewed to eliminate some faults.
It is necessary to present substantiation of mechanical strength reliability and longterm stability of building, systems and components with consideration of possible impacts of natural phenomena in the area of the site and man-induced impacts. In addition, description of calculation methods and input data for calculations should be presented.
According to requirements in the Technical Specification the Licensee shall perform a reconciliation of the codes and standards applied to the Ukrainian requirements. Reconciliation documentation shall be submitted prior to the start of the associated work. We consider the LRTP building important for safety, and therefore, besides the required scope of strength calculations, the Licensee shall present the reconciliation of construction norms and rules that he will use prior to get a construction license.
The design loads for earthquake design are still under discussion, and final conclusions have not yet been achieved. Therefore, the seismic properties of the site should be further substantiated. An inadequate design basis for earthquakes could have consequences for the dimensioning of the LRTP building.
All radioactive materials handled in the LRTP are separated from the environment by at least two containment systems. The separation between rooms providing barriers to the first containment system and rooms specifically dedicated to the second containment system is ensured by tight doors and by an air pressure difference (dynamic containment).
The description in the PSAR of the second containment system does not include provisions for the vertical connections between rooms at different levels with different classification, in particular the openings for crane load lifting (e.g. between room 126-1 and room 215-2). The RA449_WO3_TR9k)C design must ensure that at the vertical openings at least the dynamic containment will be maintained, and the air pressure difference will be as efficient, as described for horizontal connections. The Applicant should explain how this aspect would be ensured.
Quality standards for the structures, components and other systems shall be described in the PSAR or supporting documentation. A quality assurance programme at the stages of LRTP design and construction is missing in the PSAR and should be prepared.
(Quality of the results, Lesson learned, Recommendations for follow-up)
In the TACIS project UK/TS/20 the evaluation of licensing documentation for the Liquid Radwaste Treatment Plant (LRTP) was followed by a draft Preliminary Safety Analysis Report (PSAR), prior to get the construction license. However, the Licensee resolved only partially the issues, which were addressed by Riskaudit and SSTC based on the first draft PSAR.
The most urgent safety issues to be solved before commissioning the LRTP were summarised in Riskaudit Report No. 408 (January 2001). They mainly concerned radiological protection issues and formal aspects of compliance of building and equipment with Ukrainian norms and standards.