Radiation Safety

The modern Russian nuclear power plants are able to withstand the following natural and man-induced impacts:

— seismic impact up to 8 points as per MSK-64 scale;

— aircraft crash with the weight of 400 tons with the speed 200 m/sec.;

— external shock wave with compression pressure in the front of 30 MPa;

— hurricane, tornado — under rated wind speed up to 56 m/sec.;

— flooding — at the reliability level > 0,01%.

NPP safety

NPP safety is ensured by means of consecutive implementation of defense-in-depth principle based on using a physical barriers system at the way of ionizing radiation and radioactive substances distribution in the environment and the system of technical and organization measures to guard barriers and keep their efficiency, as well as to protect personnel, population and the environment.

LEVELS OF DEFENCE-IN-DEPTH

Level 1

Conditions of NPP location and prevention of normal operation failures

Level 2

Prevention of design accidents by means of normal operation systems

Level 3

Prevention of beyond design basis accidents by means of normal operation systems

Level 4

Beyond design basis accidents management

Level 5

Emergency planning

NPP safety system

A high level of NPP safety in Russia is ensured by different factors. The main of them — the reactor self-protection principle, availability of several safety barriers and multiple redundancy of safety channels.

Safety system of the modern Russian NPPs consists of four barriers at the way of ionizing radiation and radioactive substances distribution in the environment.

The first one is a fuel matrix that prevents the release of fission products under the fuel element cladding.

The second one is the cladding itself of the fuel element that prevents the fission products from entering the coolant of the main circulation circuit.

The third one is the main circulation circuit that prevents the fission products from entering under the containment.

The fourth one is the system of containment that excludes the fission products release into the environment.

The principle of defense in depth also presupposes the existence of such a concept of security, which provides not only means to prevent accidents, but also means for managing the consequences of beyond design basis accidents that ensure the localization of radioactive substances within the containment. These include hydrogen removal systems (with passive recombiners); protection of the primary circuit against overpressure; heat removal through steam generators; heat removal from the containment and core melt localization device (the so-called “molten core catcher”). For example, the system of heat removal from the containment provides a long-term heat removal under any emergency situations, including when the nuclear stations are completely de-energized. As for the core melt localization device, it ensures the melt localization and excludes the possibility of its escape beyond the containment under any scenarios. In fact, this is a cold crucible, located under the reactor and filled with so-called “sacrificial” material, which allows you to instantly suppress the reaction. Its presence makes it possible to ensure that the molten fuel “falling” into this nozzle refractory remains in a stable state, that is, the subcriticality of the melt will be maintained.

The NPP project provides for radiation monitoring systems (automated radiation monitoring system (ARMS) operating at the NPP and its industrial site and the automated radiation monitoring system (ARMS) operating outside the NPP site) that provide measurement of the monitored parameters values characterizing the radiation state at the NPP and in the environment within a certain volume under all NPP operating modes, as well as under design and beyond design basis accidents.

To monitor the environmental objects around the NPP, a network of specially equipped permanent observation points is being created. The points of observation are chosen primarily in settlements and located in four main directions in relation to the NPP: in the direction from the NPP, coinciding with the prevailing wind direction in a given locality and, respectively, in the opposite and perpendicular directions. In addition, observations are made at the control point, which should be located on the windward side from the NPP outside the radiation control area (RCA).

An obligatory component of the RME is the measurement of the gamma background in the vicinity of the NPP. Measurement of the gamma background in the field should be carried out in the territory of the NPP buffer area (BA) and RCA, as well as in the control point.

The RME in the automated mode should be implemented by ARMS. It is possible to transfer information from ARMS to The Unified State Automated Radiation Monitoring System (USARMS).

Ensuring radiation safety during construction of nuclear facilities and their decommissioning

The construction of new units of nuclear power plants on the territory of the Russian Federation is carried out on construction sites in the immediate vicinity of existing NPP and fall into the BA. Accordingly, the radiation monitoring at the nuclear power plant construction site is made by and at the cost of the customer (the NPP Radiation Safety department).

The General contractor and contracting organizations at the stage of NPP buildings and structures erection, which includes a complex of construction works, installation of equipment, auxiliary, transport and other works, production radiation monitoring is not carried out. Author’s and technical supervision of compliance with design solutions for the NPP radiation safety assurance is carried out.

JSC ASE EC and the companies that are part of management scope of JSC ASE EC (JSC NIKIMT — Atomstroy,PJSC Energospetsmontazh and VDMU LLC) have been acknowledged by the organ of state control of nuclear power — Rosatom State Atomic Energy Corporation, to be suitable for activities related to operation and decomissioning of radiation sources and storage facilities for radioactive substances.

In order to perform activities with sources of ionizing radiation, these companies have licenses for the right to perform works in the sphere of nuclear power issued by the state safety regulatory body. FMBA of Russia has granted sanitary and epidemiological permissions for the above activities. The companies have nominated persons responsible for ensuring and maintaining radiation safety. Such persons have undergone training, have obtained certification and permissions of Federal Environmental, Industrial and Nuclear Supervision Service of Russia.

Industrial radiation monitoring is performed in accordance with radiation monitoring program approved by FMBA of RF.

Individual exposure doses are accounted. Quarterly and annual doses as well as the total dose during the whole working period are accounted as well.

Exposure doses of Group A* personnel

Subdivision

Number of monitored persons

Number of persons who have received effective radiation doze (mSv)

Annual effective dose (mSv)

0-1 mSv

1-2 mSv

2-5 mSv

5-20

mSv

20-50

mSv

Above 50

mSv

JSC ASE EC

2015

9

9

0

0

0

0

0

0.26

2016

6

6

0

0

0

0

0

0.25

JSC NIKIMT-Atomstroy

2015

21

6

9

5

1

0

0

1.18

2016

21

0

0

0

0

0

0

0

PJSC ESM

2015

73

22

20

19

12

0

0

3.11

2016

43

10

8

19

6

0

0

4.38

VDMU LLC

2015

19

6

0

1

12

0

0

4.03

2016

20

5

1

5

9

0

0

3.81

* persons who, in accordance with Basic Sanitary Regulations for Radiation Safety Assurance (OSPORB-99/2010) are admitted to work with radiation sources (not younger than 18, without medical contra-indications, referred to Group A personnel in the order of the company management, having undergone training on the rules of work with radiation sources and radiation safety and radiation safety briefing).

ПАО “ЭСМ”

PJSC ESM

ООО “ВдМУ”

LLC VdMU

АО ИК “АСЭ”

JSC ASE EC

АО “НИКИМТ”

JSC NIKIMT

Exceeding of control and allowable levels agreed with FMBA on planning, production of works with radiation sources (by types of production control) of 19 mSv/year is not allowed.

The personnel is equipped with individual dose meters performing the accumulative and indicating function with a sound alarm when the radiation dose exceeds the threshold. Individual dose meters undergo annual verification with issuance of certificates.

Registration and control of radioactive substances are performed in accordance with NP-067-16 “General Rules for Accounting and Control of Radioactive Substances and Radioactive Waste in Organization”. These organizations are entered into the resister of organizations of the system of state registration and control of radioactive substances and radioactive waste.

The storage of ionizing radiation source is performed in stationary storage facilities in accordance with the requirements of radiation safety.

In order to ensure readiness to prevention of accidents at nuclear facilities, measures for prevention of accidents and incidents are in place. There are plans available to protect the personnel against radiation accident and its consequences approved by FMBA of RF. Regular drills are held in accordance with the approved programs and methods of anti-accident drills.

Sets of individual protection means is available, as well as communication facilities and tools for elimination of the consequences of radiation incidents.