Переводы документов. Translations in English

NP-008-16. Nuclear safety rules for critical test stands

Approved by

Approved by

Order of the Federal

Environmental, Industrial

and Nuclear Supervision Service

dated 23 August 2016 No. 348

 

FEDERAL RULES AND REGULATIONS

IN THE FIELD OF ATOMIC ENERGY USE "NUCLEAR SAFETY RULES

FOR CRITICAL TEST STANDS"

(NP-008-16)

 

I. Purpose and scope

 

1. These Federal rules and regulations in the field of atomic energy use “Nuclear safety rules for critical test stands” (NP-008-16) (hereinafter referred to as the Rules) are developed in accordance with Federal Law N 170-FZ “On Atomic Energy Use” dated 21 November 1995 (Collected Acts of the Russian Federation N 48, 1995, art. 4552; 1997, N 7, art. 808; 2001, N 29, art. 2949; 2002, N 1, art. 2; N 13, art. 1180; 2003, N 46, art. 4436; 2004, N 35, art. 3607; 2006, N 52, art. 5498; 2007, N 7, art. 834; N 49, art. 6079; 2008, N 29, art. 3418; N 30, art. 3616; 2009, N 1, art. 17; N 52, art. 6450; 2011, N 29, art. 4281; N 30, art. 4590, art. 4596; N 45, art. 6333; N 48, art. 6732; N 49, art. 7025; 2012, N 26, art. 3446; 2013, N 27, art. 3451; 2016, N 14, art. 1904; N 15, art. 2066), Decree of the Government of the Russian Federation N 1511 “On approval of Regulation on development and approval of Federal rules and regulations in the field of atomic energy use” dated 1 December 1997 (Collected Acts of the Russian Federation, 1997, N 49, art. 5600; 1999, N 27, art. 3380; 2000, N 28, art. 2981; 2002, N 4, art. 325; N 44, art. 4392; 2003, N 40, art. 3899; 2005, N 23, art. 2278; 2006, N 50, art. 5346; 2007, N 14, art. 1692; N 46, art. 5583; 2008, N 15, art. 1549; 2012, N 51, art. 7203).

2. These Rules shall be applicable to designed, constructed and operated critical test stands.

3. These Rules establish the requirements for the design, characteristics and operating conditions for safety-related systems and components of critical test stands as well as organizational requirements aimed to ensure nuclear safety in the course of design, construction, commissioning and operation of critical test stands.

4. These Rules are developed on the basis of safety assurance principles and requirements established in the federal rules and regulations "General safety provisions of nuclear research installations" (NP-033-11) approved by Order of the Federal Environmental, Industrial and Nuclear Supervision Service No. 348 dated 30 June 2011 (registered by Ministry of Justice of the Russian Federation on 29 August 2011; registration number No. 21700; Russian Newspaper, 2011, No. 195) (hereinafter - NP-033-11) with due regard for experience in design, development, construction and operation of critical test stands.

5. The list of abbreviations used in these Rules is given in Appendix 1 to these Rules, terms and definitions are given in Appendix 2 to these Rules.

 

II. General

 

6. The purpose of CTS safety assurance is to prevent any unauthorized transition of the critical assembly to the critical state and increase of the critical assembly power above the safe operation limits established in the design and (or) the CTS SAR and also to prevent occurrence of self-sustained chain fission reaction in the course of NM handling.

7. Nuclear safety of the CTS shall be ensured by:

1) compliance of the engineering and technical solutions used in the CTS design and engineering documentation (hereinafter - the design) with the requirements of federal rules and regulations in the field of atomic energy use and state of the art in science, technology and production;

2) adherence to the CTS design requirements in the course of the CTS construction and development;

3) usage of safety systems arranged on the basis of independence, diversity, redundancy and single failure principles;

4) application of field-proven technical solutions and substantiated methods, calculation analyses and experimental studies;

5) the system of administrative and technical arrangements aimed to mitigate the consequences of any potential human errors and unauthorized actions, equipment failures and external impacts of natural and human-induced origin;

6) implementation of the quality assurance systems, qualification of the personnel, formation and implementation of safety culture at all stages of the CTS development and operation.

 

III. Requirements for the design and engineering

documentation for a critical test stand aimed

to ensure nuclear safety

 

General requirements

 

8. Safety-related CTS systems and components shall be designed with due regard for any internal impacts possible under normal CTS operation conditions and in case of abnormal operation including design basis accidents as well as external impacts of natural and human-induced origin that can occur at the CTS site.

9. The following information shall be specified in the CTS design (operation documentation):

1) fuel load patterns defining material composition and geometrical parameters of the nuclear core and the reflector, reactivity margin and efficiency of the CPS control devices for all critical assemblies with the neutron and physical characteristics to be studied on the CTS;

2) control and testing programs and procedures in the course of installation, adjustment and operation of safety-related systems and components;

3) nuclear safety assurance conditions in the course of NM handling at the CTS outside the critical assembly;

4) operation limits and conditions, safe operation limits and conditions;

5) the list of nuclear hazardous activities in the course of the CTS operation and nuclear safety assurance measures during their performance;

6) parameters of external impacts of natural and human-induced origin requiring the CTS shutdown;

7) the list of parameters and criteria used for assessment of the residual lifetime and replacement of safety-related components;

8) the service life specified in the design;

9) analysis results for response of control and other safety-related systems to integrated impact of natural and human-induced factors typical for the CTS site;

10) analysis results for response of control and other safety-related systems to any possible failures and malfunctions of the CTS systems and equipment confirming absence of any responses dangerous for the critical assembly;

11) consequence assessment for any potential design basis and beyond design basis accidents including any accident due to the maximum possible reactivity of the critical assembly.

10. Technical solutions used in the CTS design shall provide:

1) sub-criticality of the critical assembly of at least 1% (Кeff base_1_206738_32768 0.99) after lifting of the emergency protection control devices;

2) sub-criticality of the critical assembly in the temporary CTS shutdown mode of at least 2% (Кeff base_1_206738_32769 0.98);

3) sub-criticality of the critical assembly in the long-term CTS shutdown mode of at least 5% (Кeff base_1_206738_32770 0.95);

4) the possibility for visual control (in particular through the use of television devices) of the personnel's actions in the critical assembly room from the CTS control room;

5) acoustic indication of the critical assembly power level in the critical assembly room and the CTS control room;

6) generation of the following signals transmitted to the control room (panel):

warning (light and sound) - upon approach of the controlled parameters of the critical assembly to the EP actuation setpoints and in case of any deviations from the operation limits and conditions defined in the CTS design;

indicative - informing on the position of remotely controlled reactivity control devices, the state of safety-related process systems and components and presence of voltage in the CPS power supply circuits;

7) monitoring of the critical assembly sub-criticality and (or) the CPS CD position in case of any loss of the CPS power supply from the CTS power supply sources ensuring its operation under normal conditions;

8) integrity and operability of the equipment used for recording and storage of information necessary for the accident investigation under the design basis accident conditions;

9) protection against any unauthorized access to the software means used in the CPS;

10) the personnel warning in case of any nuclear accident (alarm horn).

11. The critical assembly room shall be equipped with a water detector and the system for automatic water removal in accordance with the water detector signals in case any flooding of the critical assembly with water is possible, and flooding of the critical assembly with water results in Keff increase.

12. Technical solutions used for the CTS shall prevent:

1) entry to the critical assembly room if the critical assembly is not brought to sub-critical state;

2) increase of the critical assembly reactivity through the use of remotely controlled reactivity control devices if the door of the critical assembly room is open.

 

Critical assembly

 

13. The critical assembly design shall prevent:

1) any unauthorized modifications of the composition and configuration of the nuclear core and the reflector resulting in the critical assembly reactivity change;

2) decrease of the critical assembly sub-criticality with subsequent transition of the critical assembly to the critical (super-critical) state upon approach of the personnel and approach (withdrawal) of the process equipment;

3) sticking of the CPS control devices;

4) unauthorized lifting (ejection) of the CPS control devices and unauthorized movement of any remotely controlled experimental devices.

14. The critical assembly shall include the external (start-up) neutron source; intensity and position of this source in the critical assembly shall be selected in such a way so that insertion of the external neutron source to the critical assembly without nuclear fuel would be accompanied with increase in the parameters of the CPS start-up channels by at least twice.

15. The external neutron source in the critical assembly may be absent provided that the internal source (radionuclide, spontaneous fission or photo-neutron) is available, and it is substantiated in the CTS SAR that the critical assembly state can be monitored with the internal neutron source.

16. Fuel elements (fuel assemblies) with different enrichment or nuclide composition of nuclear fuel and neutron poisons shall have labeling (distinguishing signs).

 

Control and protection system

 

17. The following shall be provided in the CTS design within the CTS CPS:

1) the normal operation control system ensuring control of the reactivity control devices used under normal CTS operation conditions;

2) the control safety system (the EP control system) ensuring control of the reactivity control devices used in case of abnormal operation (the EP CDs).

18. The reactivity control devices used under normal operation conditions shall include reactivity compensation control devices (RC CDs), manual controller devices (MC CDs) and also automatic controller devices (AC CDs) in case an automatic power controller is used in the CPS.

19. Efficiency of each MC CD and AC CD shall not exceed 0.7 βeff

20. MC CDs, AC CDs and RC CDs shall have intermediate and end position indicators.

21. The CTS design shall specify the conditions for safe replacement and withdrawal of the CPS CDs, CPS CD actuators and other reactivity control devices from service for repair.

22. The normal operation control system shall ensure the neutron flux density (power) control within the range established in the CTS design, control of the critical assembly power and shall perform the following functions:

1) control of the MC CD, AC CD and RC CD actuators;

2) control of actuators for the loading and experimental devices;

3) monitoring of the parameters for safety-related process systems.

23. The normal operation control system shall include:

1) at least two independent neutron flux density (power) control channels with indicating instruments, in this case at least one of the channels shall be equipped with a recording device ensuring automatic registration of any neutron flux density changes in the critical assembly over time;

2) the neutron flux density change rate (period) control channel with an indicating device;

3) channels for monitoring of the parameters for safety-related critical assembly process systems;

4) the external neutron source control system (in case any external source is used);

5) the liquid level control system in case of any liquid in the nuclear core.

24. The CTS design shall provide for the neutron flux density control within the entire critical assembly power changing range in particular in case of abnormal operation including design basis accidents.

In case the neutron flux density control range is divided into several sub-ranges overlapping of the sub-ranges within at least one decade shall be provided.

25. The normal operation control system shall prevent:

1) insertion of positive reactivity with the rate of more than 0.07 βeff/sec during any movement of remotely controlled reactivity control devices;

2) insertion of positive reactivity by MC CD, AC CD, RC CD and other remotely controlled reactivity control devices in case the EP control devices are not lifted;

3) insertion of positive reactivity by the reactivity control devices in the presence of any warning alarms with regard to the neutron flux density or the neutron flux density increase rate or the control channels for the parameters of safety-related process systems;

4) insertion of positive reactivity by the reactivity control devices in case of power supply loss in the intermediate position indicator circuits of the control device  used for reactivity increase or in the emergency and warning alarm circuits;

5) the possibility for remote reactivity increase from two and more workplaces and (or) by two or more ways at the same time.

26. The normal operation control system shall ensure:

1) step-by-step motion of the RC control device with the efficiency exceeding 0.07 βeff resulting in reactivity increase by no more than 0.3 βeff with the rate of not more than 0.03 βeff/sec per each step;

2) alternation of the reactivity increase steps and subsequent pauses with the duration specified in the CTS design (operation documentation) in the course of step-by-step reactivity increase;

3) the possibility to break the power supply circuit of the actuator drives for the RC control devices with the efficiency exceeding 0.7 βeff from the CTS control room (panel), in this case the drive power supply circuit break shall not affect the possibility to bring the critical assembly to sub-critical state upon the signal of the control system;

4) automatic remote termination of reactivity increase through the use of controllable reactivity control devices in case of any warning signals in the normal operation control system.

27. Any failure of a neutron flux density control channel or a neutron flux density change rate (period) control channel shall be accompanied with failure registration, and a warning signal on such channel failure shall be generated in the CTS control room (panel).

28. In case an automatic power controller is used in the CTS the following shall be substantiated in the CTS design:

1) the critical assembly power changing range within which automatic control is provided;

2) tolerance for maintenance of the required power level;

3) stability of the automatic power control system.

29. The critical assembly and the main CTS systems shall be controlled from the CTS control room (panel) equipped with two-way loudspeaker communication with the critical assembly rooms and other CTS rooms. The CTS control room shall be equipped with telephone communications.

30. The EP shall include at least two independent EP control devices (EP CD groups).

31. Upon any EP signal regardless of the most efficient EP control device (EP CD group) the emergency protection shall ensure insertion of negative reactivity with the value of at least 1 βeff within the period not exceeding 1 s.

32. The EP shall be designed in such a way so that to ensure completion of any started protective action.

33. In case of any EP signal the EP control devices shall be automatically actuated in any positions, and insertion of negative reactivity shall be ensured at any section of the EP CD motion; in this case negative reactivity shall be also inserted by other CPS control devices.

34. The emergency protection shall perform its functions regardless of the state of the CPS power supply sources.

35. Apart from emergency shutdown of the CTS the EP control devices may be also used for scheduled CTS shutdown.

36. In case any CPS control device combines the functions of a RC CD and a MC CD and (or) AC CD and (or) EP CD safety and feasibility of such combination shall be specified in the CTS design (SAR).

37. The aggregate efficiency of all EP control devices shall be at least equal to the total efficiency of all AC CDs and MC CDs.

38. Apart from emergency protection the CTS design may provide for any other CTS shutdown systems intended to increase sub-criticality of the critical assembly and actuated automatically or by the CTS personnel. The aggregate efficiency of the CTS shutdown systems shall exceed the reactivity margin of the critical assembly.

39. The control safety system shall ensure control of the critical assembly shutdown systems and control of the end position (positions) for the EP control devices and other reactivity control devices used in the shutdown systems.

40. Subsequent to the reliability analysis results it should be demonstrated in the CTS design that the CPS unavailability factor for performance of the emergency protection function upon any EP signal does not exceed 10-5.

41. The control safety system shall be designed in such a way so that to ensure control of the critical assembly shutdown and maintenance in sub-critical state.

42. The control safety system shall include at least three independent EP channels particularly two protection channels with regard to the neutron flux density and a protection channel with regard to the neutron flux density increase rate (period); in this case the control safety system shall ensure the EP actuation upon any exceedance of the emergency setpoints established in the CTS design for any emergency protection channel.

43. In case the number of the EP channels for the neutron flux density or the neutron flux density increase rate is more than two the EP actuation by simultaneous signals from any two protection channels for the neutron flux density or any two protection channels for the neutron flux density increase rate (period) is permitted.

44. Sensitivity and location of the neutron flux density detectors of the control safety system shall ensure the possibility for the EP actuation in the course of transition to the critical state and within the entire critical assembly power range defined in the CTS design.

45. In case any protection channels operating within limited sub-ranges of the neutron flux density measurement are used in the control safety system the sub-ranges shall overlap within at least one decade. Switching of the measurement sub-ranges shall be automatic and shall not impair generation of EP signal.

46. In case the measuring parts of the EP channels are combined (united) with the measuring parts of the control channels it should be substantiated in the CTS design (or the CTS SAR) that this combination does not affect the EP capability to perform safety functions.

47. The control safety system shall prevent the EP CD lifting in the following cases:

1) the external neutron source is not inserted into the critical assembly;

2) MC CDs, AC CDs and RC CDs are not at the lower limit switches;

3) there are any warning signals with regard to the parameters of process systems.

47. The control safety system shall ensure the EP CD actuation in the following cases:

1) reaching any EP setpoint, failure or inoperable state of any EP channel;

2) reaching of the EP setpoints for process parameters;

3) any emergency signals from experimental devices requiring the critical assembly shutdown;

4) actuation of the critical assembly room flooding sensor (if any);

5) initiating of the EP actuation by the personnel through the use of the relevant buttons (keys) on the control panel and in the critical assembly room;

6) failure of the CPS power supply in particular for the power supply units of the neutron flux density detectors in the control channels or EP channels.

49. The following requirements shall be fulfilled for temporary disabling (interlocking) of the emergency alarm with regard to the neutron flux density increase rate in order to perform any experiments with the use of a pulse neutron generator, a fast-moving neutron source and any other devices changing the neutron flux density and capable to cause actuation of emergency protection for the neutron flux density increase rate but not changing reactivity:

1) the EP disabling (interlocking) time shall be substantiated in the CTS design and specified in the SAR and in the CTS operation guideline;

2) disabling (interlocking) shall be performed from the CTS control room (panel) through the use of the button which ensures prohibition of reactivity increase in any way;

3) the alarm for the EP signal disabling (interlocking) with regard to the neutron flux density increase rate (period) shall be provided in the CTS control room (panel).

50. Diagnostics of the EP channels and display of information on any failures in the CTS control room (panel) shall be provided.

51. The EP actuation setpoints determined in the CTS design shall prevent any deviations from the safe operation limits, in this case:

1) the emergency setpoint for the neutron flux density shall not exceed 120% of the value corresponding to the maximum permissible power specified in the CTS design;

2) the emergency setpoint for the neutron flux density increase period shall be at least 10 s.

52. The control safety system shall provide for output of light and acoustic emergency alarm signals to the CTS control room (panel) in order to inform the personnel on the EP actuation.

53. In case any software tools are used in the control safety system they shall be protected against any unauthorized access.

 

Loading and experimental devices

 

54. The design of loading and experimental devices shall eliminate any possibility for unauthorized changes of the critical assembly reactivity.

55. Design of the devices used for nuclear fuel loading shall prevent occurrence of self-sustained chain fission reaction.

56. In case any increase of the critical assembly reactivity by more than 0.3 βeff is possible in the course of operation of loading or experimental devices, step-by-step reactivity increase initiated by the operator shall be provided with due regard for the requirements specified in par. 26 of these Rules.

57. Remote filling of the critical assembly with separate liquid portions and (or) remote drainage of liquid in portions shall be provided for critical assemblies containing nuclear fuel solution, liquid moderator or liquid reflector and in case filling (drainage) of these liquids can result in reactivity increase.

58. Networks, dosing devices and any other equipment intended for liquid supply to the critical assembly shall eliminate any possibility for their unauthorized filling with liquid (unauthorized drainage of liquid) from the critical assembly under normal operation conditions and in case of abnormal operation including design basis accidents.

59. The liquid supply lines to the critical assembly and the liquid discharge lines shall be equipped with a device preventing liquid supply to the critical assembly (or liquid drainage) if the EP control devices are not lifted and stopping liquid supply and drainage upon any EP signal; in this case absence of liquid supply to the critical assembly (liquid discharge from the critical assembly) shall be controlled.

60. Combination of the loading and experimental device functions in one and the same unit shall be substantiated in the CTS design (SAR).

61. End position control shall be provided for remotely controlled loading and experimental devices.

 

IV. Nuclear safety assurance in preparation

of the critical test stand for commissioning

 

General requirements

 

62. Preparation of the CTS for commissioning shall provide consistent implementation of the commissioning work stage and the checkout physical start-up stage.

63. Operability of each individual CTS system and its compliance with the CTS design shall be checked and integrated verification of the CTS systems in the course of their interaction shall be performed at the commissioning work stage.

64. Compliance of the neutron and physical CTS characteristics with the CTS design shall be verified at the checkout physical start-up stage including loading of nuclear fuel into the core.

65. Commissioning works and the checkout physical start-up of the CTS shall confirm that the CTS in general as well as safety-related systems (elements) are completed and function in accordance with the CTS design.

66. Subsequent to the results of commissioning works and checkout physical start-up of the CTS the operating organization shall introduce any modifications to the CTS design and engineering documentation, SAR and  operation documentation and issue the order on the CTS commissioning.

 

Checkout physical start-up

 

67. Subsequent to acceptance of the CTS rooms, systems and equipment for operation by the operating organization the CTS readiness for checkout physical start-up shall be checked by the nuclear safety commission appointed by the order of the operating organization and the commission of the competent authority for state regulation of safety in atomic energy use.

68. The nuclear safety commission of the operating organization shall check:

1) results of the commissioning works and testing of the CTS systems, availability of the testing reports for the CTS systems and commissioning work completion certificates;

2) performance of the planned administrative and technical arrangements for nuclear safety assurance at the CTS;

3) preparedness of the personnel for commencement of the works according to the CTS checkout physical start-up program including availability of any permits for performance of works in the field of atomic energy use and results of the personnel workplace knowledge assessment.

69. Subsequent to elimination of any defects revealed by the nuclear safety commission of the operating organization the commission of the competent authority for state regulation of safety in atomic energy use shall check:

1) technical readiness of the CTS for checkout physical start-up;

2) preparedness of the personnel for checkout physical start-up;

3) availability and contents of the operation documentation.

70. Subsequent to elimination of any defects revealed by the commission of the competent authority for state regulation of safety in atomic energy use the operating organization shall issue the order on checkout physical start-up of the CTS.

71. Works for the CTS checkout physical start-up shall be performed within the framework of the checkout physical start-up program approved by the operating organization.

72. The checkout physical start-up program for the CTS shall contain:

1) the list of systems and equipment required for checkout physical start-up;

2) the procedure for the critical assembly loading;

3) the procedure for criticality achievement;

4) description of the experiments in order to define the CTS characteristics and the procedure for their performance;

5) expected critical loading of the nuclear core, critical positions (states) of the reactivity control devices, their efficiency, assessment of impact of the loaded fuel, moderating materials and the coolant on reactivity;

6) experiment and measurement procedures;

7) nuclear safety measures during checkout physical start-up.

73. Loading of nuclear fuel to the nuclear core shall start with insertion of the external neutron source to the critical assembly, the EP actuation verification and subsequent sequential lifting of the EP control devices.

Neutron flux density and neutron flux density increase rate protection setpoints providing acoustic and light alarms at the minimum power level established in the CTS design shall be set for the instruments of the control safety system.

74. Loading of nuclear fuel into the nuclear core of the critical assembly shall be accompanied with development of count-down curves according to the readings of at least two neutron flux density control channels, in this case at least two count-down curves shall have safe run. The following requirements shall be fulfilled:

1) the first portion of loaded nuclear fuel shall not exceed 10% of the design value corresponding to the critical state;

2) the second portion of loaded nuclear fuel shall be loaded after taking the readings of the neutron flux density control instruments and shall not exceed the first one;

3) the primary assessment of the critical loading shall be performed according to the count-down curve (based on the results of the curve extrapolation to zero count-down value);

4) each subsequent portion of loaded nuclear fuel shall not exceed 1/4 of the remaining value to the minimum loading corresponding to the critical state as extrapolated from the count-down curve;

5) upon reaching of Keff equal to base_1_206738_327790.98 (neutron multiplication factor base_1_206738_3278050) sequential efficiency assessment for all CPS control devices shall be performed and presence (absence) of critical state after withdrawal of all CPS control devices shall be checked.

75. Upon reaching of Keff equal to base_1_206738_327810.98 further fueling and subsequent transition to the critical state shall be carried out with inserted MC, AC and RC control devices by one of the methods described below.

In case of any direct gathering of critical mass the personnel carrying out the critical assembly loading shall perform the following actions:

1) performance of the planned additional loading; then the personnel shall leave the critical assembly room;

2) step-by-step reactivity increase through the use of RC, MC and AC control devices with due regard for the requirements of par. 26 of these Rules up to the critical assembly transfer to the critical state;

3) insertion of the RC, MC and AC control devices into the nuclear core and repetition of the previous operations specified in this paragraph in case the critical state is not reached.

In case remotely controlled loading devices are used loading shall be performed in portions subject to the critical state presence (absence) checks with step-by-step withdrawal of the CPS control devices in accordance with the requirements of par. 26 of these Rules after each additional loading with subsequent insertion of the RC, MC and AC control devices.

76. In case the critical state is reached by filling of the CTS with liquid moderator after nuclear fuel loading the moderator loading (filling) shall be arranged in portions. Amount of the portions shall be selected similar to the requirements for portion loading of nuclear fuel specified in par. 74 of these Rules.

77. After completion of checkout physical start-up the component parts of the nuclear core including nuclear fuel, moderator and the reflector components not used in the formation of the critical assembly core shall be submitted for storage in order to prevent their unauthorized use.

78. The report signed by the CTS manager shall be issued subsequent to the checkout physical start-up results where the basic results of checkout physical start-up shall be specified and compliance of the list of performed works with the checkout physical start-up program shall be demonstrated.

79. The CTS certificate shall be issued on the basis of the CTS design and the checkout physical start-up report. The CTS certificate shall specify the basic parameters of critical assemblies planned to be studied at the CTS as defined in the CTS design, configuration and characteristics of safety systems as well as numerical values of operation limits confirmed by experiments or adjusted in accordance with the checkout physical start-up results in order to ensure the CTS safety. The CTS certificate shall be issued in accordance with Appendix 3 to these Rules.

80. In case the results of checkout physical start-up demonstrate impossibility to reach the design characteristics of the CTS and necessity to make any changes in the CTS design the operating organization shall introduce the relevant modifications to the design and documents substantiating safe operation of the CTS in accordance with the requirements of par. 122-128 of these Rules.

 

V. Operation of the critical test stand

 

General requirements

 

81. Persons performing the following duties shall be appointed in the operating organization:

1) the CTS manager;

2) shift supervisors (duty research managers);

3) the CTS control engineers (control panel operators);

4) supervising physicists.

82. The list of documentation applicable to the CTS shall be developed by the operating organization, and availability of the documentation at the CTS in accordance with the list approved by the operating organization shall be ensured. The list of documents that shall be present at the workplace of the shift supervisor is given in Appendix 4 to these Rules.

83. The CTS operation shall be carried out in accordance with the CTS operation guidelines, operation manuals for the CTS systems, devices and equipment, the guidelines on nuclear safety assurance in the course of storage, refueling and transportation of nuclear fuel at the CTS that should reflect the nuclear safety measures.

The above-mentioned documents shall be updated with due regard for the obtained CTS operation experience, implementation of new federal rules and regulations in the field of atomic energy use, introduction of any changes into the CTS process systems and equipment and reviews at least once per five years.

84. The operating organization shall ensure timely familiarization of the personnel with all modifications introduced to the CTS documentation.

85. The operating organization shall arrange annual commission inspections of nuclear safety at the CTS. Results of the inspections shall be reflected in the annual nuclear and radiation safety assessment report for the CTS.

 

Start-up and power operation mode

 

86. The CTS operation in the start-up and power operation mode shall be carried out subject to compliance of the CTS parameters and technical characteristics to the nominal data and in accordance with the basic experimental program approved by the operating organization where the aim and objectives of the experiments shall be specified, the stages of research shall be defined, and the program validity period shall be indicated.

87. Working experimental programs shall be developed for each stage of the works provided in the basic experimental program and different with regard to the critical assembly parameters, applied experimental devices or methodological support; these programs shall be approved by the operating organization. Working experimental programs shall contain:

1) the aim of the works;

2) the basic characteristics of the critical assembly (including fuel load patterns, reactivity margin and efficiency of all CPS control devices of the critical assembly and other reactivity control devices provided in the CTS design for all planned states of the nuclear core), estimates of the critical parameters and assessment of the expected reactivity effects;

3) the list and procedures of experimental works;

4) nuclear safety measures.

88. Arrangement of the shift works in the course of the CTS operation in the start-up and power operation mode as well as the procedure for experiments shall be specified in the CTS operation guideline and particularized in the shift work program.

89. In the course of the CTS operation in the start-up and power operation mode a shift shall include the following personnel: the shift supervisor (duty research manager), the supervising physicist, the control engineer (control panel operator) of the CTS and any other CTS personnel as per decision of the CTS manager in order to provide maintenance of the CTS equipment and hardware as well as the personnel monitoring the radiation situation at the CTS.

90. Inclusion of a supervising physicist into the shift is not mandatory if reactivity change in the course of experiments on the critical assembly with the reactivity margin not exceeding 0.7 βeff is performed only by remote movement of the CPS control devices and experimental devices with the efficiency determined through experiments. The list of works performed without inclusion of a supervising physicist into the shift shall be defined in the CTS operation guideline.

91. All works in the start-up and power operation mode shall be performed in accordance with the shift work program. The shift work program shall be developed and approved by the CTS manager and recorded in the in-process shift log sheet (shift task log sheet).

92. The shift log program shall contain:

1) the aim of the works;

2) sequence and technique for performance of the works;

3) the list of technical and administrative measures aimed to ensure safety of the works;

4) calculation (experimental) estimates of reactivity changes in the course of works and expected value of Keff (sub-criticality) after their completion;

5) permissible power (neutron flux density) levels for the critical assembly and the permissible minimum power increase period;

6) personnel in the shift.

93. All personnel shall be familiarized with the shift work program against written acknowledgment.

94. Prior to commencement of the works in accordance with the shift work program the CTS shift supervisor shall arrange operability checks for all CTS systems important for safe performance of the future works.

95. The procedure and scope of operability checks for the CTS systems shall be described in the CTS operation guidelines. Operability of the normal operation control system and the control safety system shall be checked through the use of a neutron source.

96. Subsequent to operability checks for the CTS systems the record on the operability check results for the CTS systems, the emergency protection setpoints, the radiation situation and the CTS readiness for operation shall be made in the in-process shift log sheet (shift task log sheet) and signed by the shift supervisor.

97. Repeated (after checkout physical start-up) loading of nuclear fuel and subsequent transition to the critical state for the critical assembly with the parameters determined by experiments may be performed up to the Keff value of base_1_206738_327830.98 in portions (steps) defined in the shift work program. Continuation of the nuclear core loading and transition to the critical state shall be performed in accordance with the requirements of par. 75 of these Rules.

98. Units and parts of the critical assembly not used in the performed experiment shall be stored in the places preventing any possibility for their unauthorized use.

99. In case the control instruments for the critical assembly parameters show any conflicting readings the critical assembly shall be immediately brought into sub-critical state in order to detect the causes of such discrepancies.

100. In case any safety-affecting circumstances not taken into account in the shift work program are revealed in the course of the CTS operation in the start-up and power operation mode the critical assembly shall be brought into sub-critical state and the work shift program and the working experimental program shall be adjusted and approved again.

101. Nuclear-hazardous works including the works for maintenance, routine repair, testing and operability checks for safety-related systems may be performed in the critical assembly room in the start-up and power operation mode.

At least 2% sub-criticality shall be ensured and maintained prior to commencement of the works, in the course of the works and after their completion; in this case the neutron flux density and the neutron flux density increase rate shall be controlled, and EP setpoints providing acoustic and light alarms at the minimum power level established in the CTS design shall be set for the instruments of the control safety system.

102. The start-up and power operation mode shall be deemed completed subsequent to assurance of at least 2% sub-criticality (Кeff < 0.98) for the critical assembly, switch-off of power supply for actuators of the CPS control devices, experimental and loading devices and other reactivity control devices.

103. In case of any accident at the CTS the shift personnel shall adhere to the action plan for protection of the personnel in case of accidents at the CTS and the guidelines for the personnel's actions in case of occurrence and mitigation of any accidents at the CTS; in this case bringing of the critical assembly to sub-critical state shall be the action of top priority.

104. In case of any accident at the CTS it is prohibited to open the CPS equipment and to change any EP setpoints prior to the relevant instructions from the operating organization management.

 

Temporary shutdown mode

 

105. The temporary shutdown mode begins after insertion of the EP control devices into the nuclear core and switch-off of the power supply for the actuators of the CPS control devices, loading and experimental devices. Completion of the temporary shutdown mode - switch-on of the power supply for the actuators of the CPS control devices, loading and experimental devices.

106. At least 2% sub-criticality (Кeff < 0.98) shall be ensured and maintained in the temporary shutdown mode as per the moment of the works commencement, in the course of the works and after their completion.

107. Nuclear-hazardous works in the critical assembly room subsequent to the CTS transition into the temporary shutdown mode including any works for maintenance, routine repair, testing and operability checks for safety-related systems, equipment of the CTS with new experimental devices shall be performed by the shift and (or) repair personnel under the control of the shift supervisor in accordance with the CTS operation guidelines and the shift work program recorded in the in-process log sheet (the shift task log sheet). In this case the neutron flux density and the neutron flux density increase rate shall be controlled, and EP setpoints providing acoustic and light alarms at the minimum power level established in the CTS design shall be set for the instruments of the control safety system.

108. Subsequent to completion of the works for maintenance, repair or replacement of the components of safety-related systems their operability and compliance of their characteristics with the design values shall be checked.

109. In case it is confirmed through experiments that the works for maintenance, repair or replacement of the CTS system components performed in the temporary shutdown mode will not result in any sub-criticality decrease the shift appointment is not required. Works in the critical assembly room shall be performed by at least two workers with registration of the list and performers of the works in the in-process log sheet (the shift task log sheet).

 

Long-term shutdown mode

 

110. The CTS long-term shutdown mode shall be introduced by the order of the operating organization when the experimental works are completed and the CTS operation in the temporary shutdown mode is not feasible.

111. Prior to commencement of the CTS operation in the long-term shutdown mode the operating organization shall develop the arrangements aimed to ensure safety of the CTS in this mode and lifetime management for the safety-related system components.

112. Prior to commencement of the CTS operation in the long-term shutdown mode at least 5% CTS sub-criticality (Кeff base_1_206738_32784 0.95) shall be ensured.

113. It is permitted to use additional neutron poisons in the critical assembly or to perform partial (complete) unloading of the nuclear core in order to ensure 5% sub-criticality. Unless nuclear fuel is completely removed from the core any possibility of voltage supply to the actuators of the CPS control devices, experimental and loading devices shall be eliminated, and unauthorized withdrawal of neutron poisons from the critical assembly shall be prevented.

114. The scope and frequency of state control for the CTS systems and components in the long-term shutdowm mode shall be defined in the CTS operation guidelines.

115. The procedure for the CTS preparation for operation in the start-up and power operation mode subsequent to termination of the long-term shutdown mode shall be described in an individual working program.

116. Completion of the long-term shutdown mode and the possibility for the CTS operation in the start-up and power operation mode shall be arranged via the order of the operating organization after verification of the CTS readiness for operation in the start-up and power operation mode by the nuclear safety commission appointed by the order of the operating organization.

117. The first physical start-up of the critical assembly after the long-term shutdown mode shall be performed in accordance with the requirements of par. 67-80 of these Rules.

 

Final shutdown mode

 

118. The final CTS shutdown mode shall be introduced via the resolution of the atomic energy use controlling agency. The mode provides for implementation of administrative and technical arrangements by the operating organization in order to prepare the CTS for decommissioning, including nuclear fuel unloading from the critical assembly core and removal of nuclear fuel and other nuclear materials from the CTS site.

 

Nuclear materials management

 

119. Nuclear materials at the CTS shall be stored in the rooms specified in the CTS design and complying with the requirements of federal rules and regulations in the field of atomic energy use establishing the requirements for safety in the course of nuclear fuel storage and transportation at nuclear facilities.

120. All works with nuclear materials at the CTS shall be performed by at least two workers.

121. Temporary storage facilities for nuclear materials located in the CTS rooms shall not affect neutron and physical characteristics of the critical assembly.

122. For the CTS where reconfiguration of fuel assemblies (fuel elements) is to be performed in accordance with the experiment conditions the relevant workplaces shall be arranged in order to perform these works.

123. The operating organization shall develop the guidelines for nuclear safety assurance in the course of storage, transportation and handling of nuclear fuel at the CTS where the procedure for performance of any works with nuclear fuel and nuclear safety measures in the course of these works shall be defined.

 

VI. Requirements for introduction of modifications to the systems and components

of a critical test stand

 

124. In case any modifications of the CTS systems and components are planned the operating organization shall classify the future modifications referring them to one of the following categories:

1) the CTS refurbishment including any modifications of safety-related systems (components) leading to changes in the lists of initiating events for design basis and (or) beyond design basis accidents specified in the CTS design and also the list and values of safe operation limits and conditions thus requiring development of a new design and introduction of amendments to the CTS SAR;

2) the CTS retrofitting including modifications of any CTS system requiring adjustment of safe operation limits and/ or conditions for the CTS and introduction of changes to the CTS design and SAR (replacement of individual systems and (or) components or installation of additional ones);

3) modification (reconstruction) of the critical assembly including replacement of the existing critical assembly by another one from among critical assemblies with configurations specified in the CTS design and nuclear safety substantiated in the CTS SAR;

4) modifications of safety-related CTS systems not changing any safe operation limits and conditions for the CTS established in the CTS SAR;

5) modifications of non-safety-related normal operation CTS systems.

125. In case of the CTS refurbishment the CTS design and the CTS SAR shall be developed, and commissioning of the refurbished CTS shall be carried out in accordance with the procedure established in the CTS SAR for a newly constructed CTS in compliance with the requirements of Section IV of these Rules.

126. The CTS retrofitting shall include the following main stages:

1) development of the CTS design modifications and their approval by the CTS designers;

2) introduction of changes to the CTS SAR;

3) manufacturing, installation and testing of equipment;

4) introduction of changes to the CTS operation documentation;

5) personnel training.

127. The critical assembly modification shall be performed in accordance with the procedure established by the operating organization and shall provide for checkout physical start-up of the CTS for the purpose of experimental confirmation of the basic neutron and physical characteristics important for nuclear safety assurance at the CTS after the critical assembly modification.

128. Modifications associated with replacement of replaceable safety-related system components and experimental devices and not changing any safe operation limits and (or) conditions and results of the consequence analysis for any potential accidents considered in the CTS SAR shall be recorded in the CTS operation documentation according to the procedure established by the operating organization.

129. Modifications not affecting the CTS safety shall be introduced in accordance with the procedure established by the operating organization; in this case all introduced modifications shall be reflected in the CTS operation documentation and their classification as non-safety-related modifications shall be substantiated.

130. Results of any modifications of safety-related CTS systems shall be specified in the annual nuclear and radiation safety assessment report for the CTS.

 

 

 

 

 

Appendix 1

to federal rules and regulations

in the field of atomic energy use

"Nuclear safety rules

for critical test stands"

approved by Order of the Federal

Environmental,

Industrial and Nuclear Supervision Service

dated 23 August 2016 No. 348

 

ABBREVIATIONS

 

EP

-

Emergency Protection

AC

-

Automatic Controller

RC

-

Reactivity Compensator (compensation device)

CTS

-

Critical Test Stand

Кeff

-

Effective neutron multiplication factor

SAR

-

safety analysis report

CD

-

Control Device

MC

-

Manual Controller

CPS

-

Control and Protection System

-

-

Operating Organization

NM

-

Nuclear Materials

βeff

-

effective fraction of delayed neutrons

 

 

 

 

 

Appendix 2

to federal rules and regulations

in the field of atomic energy use

"Nuclear safety rules

for critical test stands"

approved by Order of the Federal

Environmental,

Industrial and Nuclear Supervision Service

dated 23 August 2016 No. 348

 

TERMS AND DEFINITIONS

 

Terms and definitions specified in NP-033-11 as well as the following terms and definitions are used in these Rules.

Emergency protection:

safety function including emergency (fast) shutdown of the CTS;

the set of safety systems performing the emergency protection function.

Emergency signal - a signal generated in the EP hardware in order to initiate actuation of the EP control devices and transmitted to the recording equipment as well as to the control panel for the personnel warning.

Safe run of the count-down curve - the type of the count-down curve when the extrapolated value of the parameter used for the critical state achievement corresponding to the critical state of a multiplying system is understated.

Lifting of the control devices of the control and protection system and other reactivity control devices - change in the position (state) of the CPS control devices and other reactivity control devices resulting in positive reactivity insertion.

Group of the CPS control devices - one or several CPS control devices with common control for simultaneous joint movement and impact on reactivity.

Loading devices of the critical test stand - transportation and handling equipment, mechanisms and devices used for loading (reloading) of the critical assembly and nuclear fuel to the nuclear core, filling of liquid (including nuclear fuel solution) and installation (withdrawal) of experimental devices.

Reactivity margin of the critical assembly - positive reactivity which can be effected with the selected critical assembly configuration and geometry in case of lifting of all CPS control devices and any other reactivity control devices to the maximum efficiency.

Control channel - a set of sensor(s), communication line and means for signal processing and  information displaying intended to ensure the parameter control.

Start-up channels of the control and protection system - neutron flux density (power) control channels providing control from the neutron flux density level corresponding to activity of the external (start-up) neutron source up to the level reliably controlled via other neutron flux density control channels (if any are used).

Checkout physical start-up of the critical test stand - the stage of the CTS preparation for commissioning including the first nuclear fuel loading into the core and subsequent transition of the critical assembly to the critical (super-critical) state and to power in order to study its basic neutron and physical characteristics and the radiation situation at the CTS for experimental confirmation of the CTS safety.

Count-down curve of a multiplying system - dependence of the system reverse multiplication from the parameter changing its multiplying properties.

Critical assembly - a set for experimental studies of systems containing fissile materials with the configuration and geometry enabling to arrange controlled self-sustained chain nuclear fission reaction operated at the power level not requiring any forced heat removal and not affecting its neutron and physical characteristics.

Maximun possible reactivity of a critical assembly - maximum super-criticality of a critical assembly which can occur due to erroneous decisions of the personnel and failures in the CTS systems in case of withdrawal of all reactivity control devices and removable poisons from the nuclear core.

Shutdown of the critical assembly - transfer of the critical assembly from the critical (super-critical) state to the sub-critical state through the use of the CPS control devices and other shutdown systems and operation of the critical assembly in the sub-critical state.

Emergency shutdown of the critical assembly - transfer of the critical assembly from the critical (super-critical) state to the sub-critical state through the EP actuation.

Scheduled shutdown of the critical assembly - transfer of the critical assembly from the critical (super-critical) state to the sub-critical state through the use of MC, AC and RC control devices with subsequent or simultaneous insertion of the emergency protection control devices.

Nuclear core refueling (reloading) - nuclear-hazardous works on the critical assembly for the nuclear fuel solution filling (drainage), withdrawal and transportation of fuel elements, fuel assemblies, components of experimental devices and tested samples, reactivity control devices and other reactivity-affecting elements for the purpose of their repair, replacement or dismantling.

Preparation of the critical test stand for commissioning - activity including commissioning works and checkout physical start-up of the CTS when compliance of individual systems and equipment and the entire CTS with the design is verified.

Actuator of the control and protection system control device - the device intended to change the position of the CPS control device and to hold it in the fixed position.

Commissioning works - the stage of the CTS commissioning when operability and compliance with the design are verified for each CTS system separately and integrated check of systems in the course of their interaction is performed.

CPS control device - a reactivity control device used in the CPS and ensuring reactivity variation through its position (state) changing.

In accordance with their functional purpose the CPS control devices are divided into the emergency protection control devices, manual reactivity control devices, automatic reactivity control devices and reactivity compensation control devices.

Reactivity control devices - the CPS control devices, loading, experimental and other devices located in the nuclear core and changing the critical assembly reactivity in case of their movement or state variation.

Experimental devices of the critical test stand - devices, units, instruments and equipment used to carry out experimental studies at the CTS.

 

 

 

 

 

Appendix 3

to federal rules and regulations

in the field of atomic energy use

"Nuclear safety rules

for critical test stands"

approved by Order of the Federal

Environmental,

Industrial and Nuclear Supervision Service

dated 23 August 2016 No. 348

 

(recommended sample)

 

                        Critical test stand certificate

 

1. Name of the critical test stand, type of the critical assembly ...........

.............................................................................

    (nuclear fuel type and enrichment, moderator material, reflector

             material, geometry of the core and the reflector)

2. Location .................................................................

3. Critical test stand designers ............................................

4. Operating organization ...................................................

5. Date of the critical test stand commissioning ............................

6. <*> Reactivity margin of the critical assembly,βeff .......................

7. Maximum reactivity margin, βeff ...........................................

8. Maximum permissible power, W .............................................

9. Limit values of process parameters <*> ...................................

10. CPS characteristics:

10.1. Control channels:

    a) with regard to neutron flux density ..................................

                                                (type and number of channels)

    b) with regard to the neutron flux density increase period ..............

(type and number of channels)

10.2. Emergency protection channels:

    a) with regard to neutron flux density ..................................

                                               (type and number of channels

                                                      and instruments)

    b) with regard to the neutron flux density increase period ..............

(type and number of channels and instruments)

    c) data on combination of protection and control functions ..............

    10.3. Adjustment and compensation control devices <*> ...................

                                                            (number,

                                                           efficiency,

                                                          response time)

    10.4. Emergency protection control devices ..............................

                                             (number, efficiency,

                                                   response time)

11. Shutdown systems used in addition to emergency protection ...............

                                                                     (type,

.............................................................................

        method of actuation, efficiency, response time)

12. Experimental and loading devices <*> ....................................

                                                      (type, purpose,

                                                    maximum introduced

                                                        reactivity)

13. Design (specified) service life .........................................

14. Additional information ..................................................

15. The certificate is issued on the basis of ...............................

 

                 Chief executive officer of the operating organization

                 ________________________________________

                             (Full name/ signature)

 

                .... ............. 20 ....

 

                            L.S. (if any)

 

--------------------------------

<*> Potential ranges of change for the parameters and neutron and physical characteristics may be additionally specified in case they are determined in the critical test stand design.

 

 

 

 

 

Appendix 4

to federal rules and regulations

in the field of atomic energy use

"Nuclear safety rules

for critical test stands"

approved by Order of the Federal

Environmental,

Industrial and Nuclear Supervision Service

dated 23 August 2016 No. 348

 

LIST

OF DOCUMENTS TO BE PRESENT AT THE WORKPLACE

OF THE SHIFT SUPERVISOR

 

1. Technical design and any other technical documentation of the CTS including descriptions, certificates, drawings and diagrams of safety-related systems and components.

2. The list of regulatory documents on safety of nuclear facilities effective at the CTS.

3. The CTS safety analysis report.

4. The CTS checkout physical start-up program (for newly constructed and refurbished CTSs).

5. Report on the checkout physical start-up results.

6. Basic experimental program.

7. Working experimental programs.

8. General and individual quality assurance programs for the CTS.

9. The CTS operation guideline.

10. Operation manuals for the CTS systems and equipment.

11. Action plan for protection of the workers (personnel) in case of accident at the CTS.

12. Guidelines for the personnel's actions in case of occurrence and mitigation of any accidents at the critical test stand.

13. Guidelines on nuclear safety assurance in the course of storage, transportation and handling of nuclear fuel at the CTS.

14. Lifetime management program for safety-related CTS systems (upon reaching of the specified or 30-year period of operation).

15. In-process documentation including the in-process shift log sheet and the fuel loading pattern logs.

16. CTS commissioning work completion certificate.

17. Periodic testing reports and protocols for safety-related CTS systems.

18. Reports of the nuclear safety commission.

19. Order of the chief executive officer of the operating organization on the CTS commissioning.

20. Job descriptions for the CTS personnel.

21. The list of documentation effective at the CTS.

22. Proficiency assessment reports for the shift personnel of the CTS.

23. Orders (extracts from orders) on appointment of the CTS personnel for certain positions.

24. The personnel's permits for performance of works in the field of atomic energy use.

25. The CTS certificate.

26. Periodical safety assessment reports for the CTS.

27. Schedules of routine preventive and repair works for safety-related systems.

28. Schedules of testing and operability verifications for the CTS safety systems.

 

 

 

 


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