STATE NUCLEAR REGULATORY INSPECTORATE OF
BOARD RESOLUTION
| 19 May 2011 | Kyiv | No. 2 |
| On Action Plan for special targeted safety reassessment and further safety improvement of Ukrainian NPPs in the light of the events at Fukushima-1 (“stress tests”) |
Two severe accidents occurred in the history of nuclear energy before March 2011: Three Mile Island NPP (
The
The Chornobyl accident was the largest in the history of nuclear energy. The accident resulted in radioactive contamination to extensive areas, and its consequences were highly detrimental to human health and the environment. The causes of the accident were investigated to reveal deviations from safety requirements in the design and operation of the nuclear power plant. Measures were developed and implemented to prevent similar accidents in future. The IAEA’s International Nuclear Safety Advisory Group (INSAG) prepared summary reports on the accident (INSAG-1 and INSAG-7) and reports on basic safety principles (INSAG-3) and safety culture (INSAG-4). The international nuclear safety regime was promoted under the Convention on Nuclear Safety and other international agreements, approaches to regulation of nuclear and radiation safety were improved, and the fundamental principle of safety culture was implemented into everyday practices.
In view of the measures implemented, the nuclear community built confidence that no severe accidents were likely to occur and substantially affect personnel, the public, and the environment. However, the expectations have not been met.
On 11 March 2011, the Fukushima-1 NPP (
According to preliminary data, the accident at Fukushima-1 (
- an earthquake of more than 9 magnitude according to the Richter scale that led to loss of off-site power and damage of a part of equipment;
- a tsunami that was induced by the earthquake (with a wave higher than
- dependent loss of safety functions such as residual heat removal, heat removal to ultimate heat sink, and reactor coolant level, confinement of radioactivity, which are performed by active safety systems.
The Fukushima-1 events have posed new challenges to the nuclear community, which has to carry out a detailed analysis of the courses and learn lessons from the accident and develop and implement measures to prevent severe accidents or, if such an accident occurs, prevent its adverse effects on the public and environment.
On 24 March 2011, the Council of the European Union declared that the safety of all EU nuclear power plants should be reviewed on a basis of a comprehensive and transparent risk assessment ("stress tests"). The Western European Nuclear Regulators Association (WENRA) organized the development of “stress test” specifications, involving Ukrainian experts as well. According to WENRA, “stress tests” are defined as a targeted reassessment of the safety margins of nuclear power plants in the light of the events that occurred at Fukushima-1. Extreme natural events and their combinations challenging the plant safety functions and leading to a severe accident should be analyzed in detail.
At the Fifth Review Meeting under the Convention of Nuclear Safety (4-14 April 2011), the member countries made a common statement and identified a need to conduct safety reassessments at NPPs and take additional immediate actions regarding the accident at Fukushima-1.
The improvement of operational safety at all Ukrainian nuclear power plants in the light of the Fukushima-1 accident was discussed at the meeting of the National Security and Defense Council of Ukraine (NSDC) on 8 April 2011. The NSDC resolutions, indicating a need for a special in-depth safety assessment of Ukrainian NPPs including seismic analyses, were implemented by Presidential Decree No. 585/2011 of 12 May 2011.
On 17 March 2011, the “Statement of the State Nuclear Regulatory Inspectorate of Ukraine Relating to the Events at Fukushima-
In cooperation with the State Technology-Related Safety Inspectorate of Ukraine and National Nuclear Utility Energoatom, the State Nuclear Regulatory Inspectorate of Ukraine (SNRIU) developed an action plan to perform a special targeted safety assessment and promote further safety improvement of Ukrainian NPPs in the light of the events at Fukushima-1, which includes short-term and long-term measures.
Short-Term Measures
1. Special targeted safety assessment of NPPs (“stress tests”)
A special targeted safety assessment focuses on the response of NPPs to external natural events that lead to the loss of basic safety functions and, consequently, to severe accidents and is intended to:
- evaluate NPP vulnerability to external natural events;
- identify countermeasures to ensure NPP robustness under multiple equipment failures.
The targeted safety assessment is performed individually for each site, taking into account differences between the sites and specific features of different types of power units. Nuclear fuel in the reactor core, cooling pool, and fresh fuel storage is considered. All operational states of the power units should be analyzed.
The assessment of NPP vulnerability to external events will cover:
- earthquakes and tornados;
- external flooding (resulting from high waters and precipitations for all NPPs and from accidents at hydraulic structures for Zaporizhya NPP);
- external fires (for Rivne and Khmelnitsky NPPs).
- extreme high/low temperatures.
The assessment will provide the following information:
- confirmation of design characteristics (levels) of events;
- confirmation of safety margins for design-basis events;
- threshold levels of events (based on design provisions or safety analysis report) at which basic safety functions are degraded and design limits are challenged.
To identify countermeasures to ensure NPP stability under multiple equipment failures, the loss of safety functions is considered for all power units at the NPP site:
- major blackout of the NPP site;
- loss of ultimate heat sink;
- combination of two above events.
The assessment of loss of safety functions should identify:
- assumed accident progression under postulated events;
- available time before severe damage of nuclear fuel;
- additional adverse effects induced by a severe accident;
- technical and administrative provisions for recovery of basic safety functions (in particular, residual heat removal from the reactor core and fuel storage pool during 72 hours in case of major blackout) to prevent incompliance with acceptance criteria for severe accidents. The main acceptance criterion is limitation of radioactive accident releases below the levels that require public evacuation at the boundary of the NPP controlled area.
2. Targeted assessment of emergency preparedness:
- conduct emergency training at Zaporizhya NPP on 25 May 2011 under an extended scenario agreed upon with the SNRIU and Ministry of Emergencies (considering the events at Fukushima-1);
- taking into account results of the training at Zaporizhya NPP, determine the scope and schedule for additional, special emergency training at a state level, with involvement of central and local executive bodies;
- conduct additional special emergency training at a state level;
- taking into account results of the additional special emergency training at a state level, develop measures to improve the emergency response and preparedness system.
3. Revision and amendment of the Comprehensive (Integrated) Safety Improvement Program (upgrade package) for Ukrainian NPPs and the Schedule of Measures for 2011:
- include safety improvement measures into upgrade package to be taken immediately, without additional studies (for example, introduce a system for forced emergency steam dump from the containment);
- review (increase) priorities of measures directly related to the prevention of severe accidents and/or mitigation of their consequences.
4. Analysis of the regulatory and legal framework on nuclear and radiation safety and development of proposals for its improvement and establishment of stricter safety requirements for operating and new power units.
Long-Term Measures
Short-term measures should be followed by long-term measures in response to the events at Fukushima-1 to improve safety of Ukrainian NPPs. The long-term measures will be based on results of the special targeted safety assessment:
- upgrade package amended to incorporate results from targeted review of standards and rules on nuclear and radiation safety;
- improvement of the emergency response and preparedness system resulting from targeted assessment of NPP emergency preparedness.
Based on the review and discussion of the Action Plan for special targeted safety assessment and further safety improvement of NPP units in the light of the events at Fukushima-1 and the scope and methods of the targeted safety assessment, the Board of the State Nuclear Regulatory Inspectorate of Ukraine
decrees the following:
1. Agree the Action Plan for special targeted safety assessment and further safety improvement of NPP units in the light of the events at Fukushima-1.
2. National Nuclear Utility Energoatom: perform the special targeted safety assessment of Ukrainian NPPs in compliance with the agreed approaches.
Deadline: 15 October 2011
3. National Nuclear Utility Energoatom, Ministry for Energy and Coal Industry, State Nuclear Regulatory Inspectorate, and Ministry of Emergencies: conduct additional special training at a state level, with involvement of central and local executive bodies.
Deadline: 30 September 2011
4. Conduct an extended meeting of the Board of the State Nuclear Regulatory Inspectorate to discuss results of the special targeted safety assessment of Ukrainian NPPs and targeted assessment of emergency preparedness, approve additional measures on safety improvement of nuclear power units.
Deadline: 24 November 2011
5. State Nuclear Regulatory Inspectorate, State Agency for Exclusion Zone Management, and Chornobyl NPP: identify areas, scope, and schedule for special targeted safety assessment of Chornobyl facilities, specifically: power units 1–3 (regarding safety of spent fuel management) and Interim Spent Fuel Storage Facility ISF-1.
Deadline: 15 June 2011
6. State Nuclear Regulatory Inspectorate and State Technology-Related Safety Inspectorate: establish a task force and prepare proposals on an action plan to improve fire safety at Ukrainian NPPs and an efficient method to coordinate regulation and supervision, with subsequent review at a joint meeting of the boards.
Deadline: July 2011
7. State Nuclear Regulatory Inspectorate and Security Service and Other Competent Bodies of Ukraine: establish a joint task force and prepare proposals on the format, methods, and schedules for assessing the security and protection of Ukrainian NPPs against terrorist threats and illegal actions.
Deadline: July 2011
Board Chairperson O. A. Mykolaichuk
Board Secretary N. S. Kumetska