Provisional Translation(Feb.13,2013 Rev.0）

February 6, 2013

Outline of New Safety Standard (Design Basis)(DRAFT)For Public Comment0February 6, 2013
Outline of New Safety Standard (Design Basis) (DRAFT)

Table of Contents
1. General ............................................................................................................ 4(1) Definitions of terms ...................................................................................... 4(2) Applicable standards ..................................................................................... 7
2. Common technical requirements for reactor facilities ............................................ 8(1) Design considerations for natural phenomena (Guide 2) ................................... 8(2) Design considerations for external human events ........................................... 10(3) Design considerations for internally generated missiles (Guide 4) .................... 11(4) Design considerations for internal flooding (New) ......................................... 12(5) Design considerations for fire (Guide 5) ........................................................ 13(6) Design considerations for environmental conditions ....................................... 14(7) Design considerations for common use ......................................................... 15(8) Design considerations for operator manipulations .......................................... 16(9) Design considerations for reliability.............................................................. 17(10) Design considerations for testability............................................................ 19(11) Design considerations for telecommunication systems .................................. 21(12) Design considerations for evacuation routes................................................. 22
3. Individual systems within the reactor facility...................................................... 23(1) Core, etc. ................................................................................................... 23
Guide 11. Core design
Guide 12. Fuel design
Guide 13. Reactor attributes(2) Reactivity control systems and reactor shutdown systems ............................... 25
Guide 14. Reactivity control system
Guide 15. Independence and testability of reactor shutdown system
Guide 16. Control rod reactor shutdown margin
Guide 17. Shutdown capability of reactor shutdown system
Guide 18. Capability of reactor shutdown system during accidents(3) Reactor coolant pressure boundary ............................................................... 28
Guide 19. Integrity of reactor coolant pressure boundary
Guide 20. Preventing failure of reactor coolant pressure boundary1

Guide 21. Leak detection of reactor coolant pressure boundary
Guide 22. In-service inspections and tests of reactor coolant pressure boundary(4) reactor cooling systems ............................................................................... 30
Guide 23. Reactor coolant makeup system
Guide 24. System to remove residual heat
Guide 25. Emergency core cooling system
Guide 26. System to transfer heat to the ultimate heat sink
New: Steam turbine facilities subject to regulation under the Reactor
Regulation Act due to the consolidation of the Electricity Business Act
and Reactor Regulation Act.
(5) Reactor containment facilities ...................................................................... 35
Guide 28. Functions of the reactor containment vessel
Guide 29. Preventing failure of the reactor containment vessel boundary
Guide 30. Isolation functions of the reactor containment vessel boundary
Guide 31. Reactor containment vessel isolation valves
Guide 32. Reactor containment vessel heat removal system
Guide 33. System to control containment facility atmosphere(6) Measurement and control systems ................................................................ 40
Guide 47. Instrumentation and control system
Guide 34. Redundancy of safety protection system
Guide 35. Independence of safety protection system
Guide 36. Function of safety protection system during transients
Guide 37. Function of safety protection system during accidents
Guide 38. Function of safety protection system during failure
Guide 39. Separation of safety protection system and instrumentationand control system
Guide 40. Testability of safety protection system
Guide 42. Control room
Guide 43. Design considerations for control room habitability
Guide 44. Nuclear power plant emergency response center(7) Electric systems .......................................................................................... 49
Guide 48. Electrical system
New: Nuclear generation facilities subject to regulation under the Reactor
Regulation Act due to the consolidation of the Electricity Business Act
and Reactor Regulation Act.

2

(8) Design considerations toward station blackout ............................................... 53
Guide 27. Design considerations for loss of power(9) Radioactive waste processing facilities.......................................................... 54
Guide 52. Radioactive gaseous waste treatment facilities
Guide 53. Radioactive liquid waste treatment facilities
Guide 54. Radioactive solid waste treatment facilities
Guide 55. Solid waste storage facilities(10) Fuel handling systems ............................................................................... 56
Guide 49. Fuel storage facilities and handling facilities
Guide 50. Preventing criticality of fuelGuide 51. Monitoring of fuel handling areas(11) Radiation control ...................................................................................... 58
Guide 56. Surrounding area radiation protection
Guide 57. Radiation protection of radiological workers
Guide 58. Radiation management of radiological workers
Guide 59. Radiation monitoring(12) Miscellaneous........................................................................................... 62
New: Auxiliary boiler subject to regulation under the Reactor Regulation Act
due to the consolidation of the Electricity Business Act and Reactor
Regulation Act.
4. Safety evaluation ............................................................................................. 63(1) Safety evaluation ........................................................................................ 63(Caution)This document contains the new safety standards (Severe Accident Management)
outline compiled based on the discussions by the “The Study Team on the New
Safety Standards for Light Water Reactor for Electric Power Generation”.

This document compiles regulatory requirements in a free format. Legislative
structure, definitions of terms, and detailed provisions shall be determined in the
future in accordance with legal examples.



Review of the “Regulatory Guide for Reviewing Classification of Importance of
Safety Functions for Light Water Nuclear Power Reactor Facilities” (Nuclear
Safety Commission Decision August 30, 1990) is planned. Item “2. (7) Design
considerations for common use” and “Item 2. (9) Design considerations forreliability” are planned for review in advance of developing future regulatory
guides.

3

1. General(1) Definitions of terms
The terms in the following items as used in this draft outline are defined according to
the provisions of each of the relevant items (corresponding to the definitions in thedesign guidelines).
①“Safety function” is the function of necessary structures, systems, and components toensure safety of the reactor facility and may be categorized as following.
1) Those that, if lost, may lead to abnormal transients during operation of thereactor facility and design basis accident, leading to excessive radiation
exposure to the general public or workers.
2) Those that prevent the expansion of or quickly resolve abnormal transientsduring operation of the reactor facility or design basis accidents thereby
preventing or mitigating excessive radiation exposure to the general public orworkers and radioactive contamination of the environment outside of thereactor site premises.
②“Importance of safety functions” is the level of importance of the safety function
from the perspective of ensuring the safety of the reactor facility.
③“Normal operation” is planned startup, shutdown, power operation, hot standby,
refueling and other operations of the reactor facility that are within designated limitsof the operating conditions.
④“Abnormal transients during operation” are abnormal conditions that arise due toforeseen equipment single failures or spurious actions, single operator erroneous
operations during the lifetime of the reactor facility or caused by disturbancespredicted to occur at similar frequencies.
⑤“Design basis accident” (DBA) is an abnormal condition exceeding an “abnormaltransient during operation” which has an occurrence frequency that is rare but isassumed to occur from the perspective of the safety design of the reactor facility.
⑥“Reactor containment vessel boundaries” are the equipment that are designed to be
the pressure barrier against assumed reactor containment vessel events and which
form the barrier against release of radioactive materials.
⑦“Reactor coolant pressure boundaries” are the equipment that contain reactor coolant(primary coolant for pressurized water reactors) during normal reactor operation, andwhich constitute the pressure barrier during abnormal transients during operation anddesign basis accidents, leads to loss of coolant accident, if damaged⑧“Reactor coolant systems” are systems for reactor coolant which directly cool thecore during normal reactor operation (primary cooling system in pressurized water
reactors, primary loop recirculation system, main steam system, and feedwater
system for boiling water reactors).
⑨“Reactor cooling systems” are the systems to remove heat from the reactor during4normal reactor operation, abnormal transients during operation, and design basis
accidents (including reactor coolant system, systems to remove residual heat,
emergency core cooling system, secondary cooling systems (for pressurized water
reactors), and systems to transfer heat to the ultimate heat sink).
⑩“Reactor shutdown systems” are the systems designed to bring the reactor subcriticalby injecting negative reactivity to the reactor from critical or supercritical conditions.
⑪“Reactivity control systems” are the systems designed to adjust reactivity change
depending on the reactor output, burn-up, fission products, temperature, and otherelements by controlling the reactivity of the reactor.
⑫“Safety protection systems” are the systems designed to detect abnormal transientsduring operation of reactor facilities and design basis accidents, and, if necessary,
directly actuate the reactor shutdown systems, engineered safety facilities, and othersystems.
⑬“Engineered safety facilities” are the equipment designed to constrain or prevent
massive release of radioactive materials in the unlikely event of failure of fuel in thereactor caused by damage or failure of the reactor facility.
⑭“Single failure” refers to the loss of prescribed safety functions due to failure of one
component. It also includes multiple failures based on dependent causes. “Dependentcauses” refers to causes that occur inevitably due to a single cause.
⑮“Active components” refer to the components that actively execute prescribedfunctions in response to actuation signals or inputs from components, such as
actuators, other than the said one.
⑯“Passive components” refer to the components that are not active components.
⑰“Redundancy” refers to having two or more systems or components that have thesame properties with the same functions.
⑱“Diversity” refers to having two or more systems or components that have thedifferent properties with the same function. “Different properties” as referenced
herein refers to having different operation principles and functions that are notsimultaneously hindered by common causes or dependent causes. “Common cause”
refers to the causes that act simultaneously on two or more systems or components
such as impact factors of environmental temperature, humidity, pressure, orradiation; and, impact factors of power, air, oil, cooling water supplied to systems orcomponents, in addition to, impact of earthquakes, flooding, or fire.
⑲“Independence” refers to when the functions of two or more systems or components
are not simultaneously hindered due to common causes or dependent causes during
environmental and operating conditions considered in design.
⑳“Allowable design limit of fuel” is the allowable level of fuel damage in terms ofsafety with regard to reactor design and is the limit at which the reactor may continue
operation. “Reactor may continue operation” herein does not necessarily refer to5operation of the reactor in an as-is condition, but includes restart of operations after
repairing the relevant failure and inspect/replace the fuel, if necessary.

61. General(2) Applicable standards[Basic requirement]
Design, selection of materials, production, and inspection of structures, systems, andcomponents with safety functions shall be according to the codes and standards
recognized as appropriate in consideration of the level of importance of the intended
safety function.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 1)[Requirement Details]
A In principle, design, selection of materials, production, and inspection of structures,
systems, and components with safety functions shall be according to the codes andstandards based on current domestic laws. However, if the applied codes andstandards are from other countries or if the codes and standards are not generally
used, it is necessary to clarify the basis for applying these codes and standards, tocompare them to domestic laws, and to explain the validity of their application.
B“Shall be according to the codes and standards” means that the applicable codes andstandards shall be clarified regarding the design, selection of materials, production,and inspection of applicable structures, systems, and components.

7

2. Common technical requirements for reactor facilities(1) Design considerations for natural phenomena (Guide 2)[Basic requirement](Earthquakes, tsunamis (including accompanying events)
1. Structures, systems, and components with safety function shall be classified forseismic design considering the importance level of its safety function and the impact
on safety if functions were lost due to earthquake, and it shall be designed to
sufficiently withstand the design seismic force as considered appropriate.
(* The above is written based on the current Safety Design Regulatory Guide, butshall be replaced by the results of the on-going separate study team examining
design basis earthquakes/ tsunamis (including accompanying events).)(Natural phenomena other than earthquakes)
2. Structures, systems, and components with safety functions shall be designed so as to
not impair safety of the reactor facilities due to assumed natural phenomena other thanearthquakes, tsunamis, and accompanying events. For structures, systems, andcomponents with particularly high level of importance in their safety functions, thedesign shall consider the severest conditions among the predicted natural phenomena
and an appropriate combination of the natural forces and accident loads.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 2)[Requirement Details]
A “Design to sufficiently withstand the design seismic force as considered appropriate”
shall be according to provisions in the Regulatory Guide for Reviewing Seismic
Design of Nuclear Power Reactor Facilities (Nuclear Safety Commission Decision
September 19, 2006).
B“Design so as to not impair safety of the reactor facilities due to natural phenomena”
refers to, in case natural phenomena necessary to be considered for design or a
combination of such natural phenomena occurs, the safety function of theequipment shall be achieved under the environmental conditions brought on by thenatural phenomena and the environmental conditions arising at the facility as aresult.

8

C“Structures, systems, and components with particularly high level of importance intheir safety functions” shall be separately provided for based on the Regulatory
Guide for Reviewing Classification of Importance of Safety Functions for Light
Water Nuclear Power Reactor Facilities (Nuclear Safety Commission Decision
August 30, 1990).

D“Predicted natural phenomena” are those applicable phenomena based on thenatural environment of the site including flooding, wind (typhoon), tornado,
freezing, precipitation, snow accumulation, lightning, landslide, volcanic effects,
biological events, forest fires and others.

E“The most severe conditions among the natural phenomena” are those that may be
predicted based on the newest scientific and technological knowledge regardingthat natural phenomenon. Based on the past records, results of field investigations,the newest knowledge, the combination with other natural phenomena shall all beconsidered.

F“A combination of the natural force and accident load” does not necessarily requirethat the natural force considered the most severe and the accident load to be themaximum load during an accident. Instead it refers to an appropriate combinationconsidering respective cause and chronological relationships between these forces
and loads.

92. Common technical requirements for reactor facilities(2) Design considerations for external human events[Basic requirement](Random event)
1. Structures, systems, and components with safety functions shall be designed so thatassumed random external human events do not impair safety of the reactor facility.
(Illegal approach by third parties)
2. The reactor facility shall be designed with the appropriate measures to protect against
illegal approach by third parties to those structures, systems, and components withsafety functions.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 3)[Requirement Details]
A “Random external human events” are selected based on the conditions of the site
and the site location and refers to missiles (airplane crashes), dam collapses,
explosions, fires in nearby factories, toxic gases, ship collisions, electromagnetic
interference, and others.
B

For airplane crashes, the necessity for a protective design shall be confirmed basedon the “Assessment of airplane crash probability for commercial power reactor
facility (2009.06.25 NISA-1)” stipulated as of July 30, 1995 and revised as of June30, 2009 by the former Nuclear and Industrial Safety Agency.

C“Illegal approach by third parties” includes: illegal transport of nuclear material bypeople on-site, sabotage, transport of explosives or hazardous materials onto thesite including using mail and cyber terrorism.

10

2. Common technical requirements for reactor facilities(3) Design considerations for internally generated missiles[Basic requirement]
Structures, systems, and components with safety functions shall be designed so that thesafety of the reactor facility is not impaired by missiles that may be assumed to begenerated within the reactor facility.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 4)[Requirement Details]
A “Internally generated missiles” refer to the missiles generated by breakage of valvesor pipes containing fluid with high internal energy, breakage of high-speed rotating
equipment, gas explosions, and the dropping of heavy equipment. Secondary
missiles, fires, chemical reactions, electrical damage, piping breakage, equipment
failures and other secondary impacts shall also be considered.
B

Assessment of internally generated missiles shall be according to “Assessment of
turbine missiles” (Nuclear Safety Commission, Reactor Safety Dedicated Review
Committee, July 20, 1977) and other appropriate documents.

112. Common technical requirements for reactor facilities(4) Design considerations for internal flooding[Basic requirements]
Structures, systems, and components with safety functions shall be designed so that thesafety of the reactor facility is not impaired by flooding that is assumed to occur
internally in the reactor facility.
(New)[Requirement Details]
A “Flooding that is assumed to occur internally in the reactor facility” refers to theflooding caused by breakage of components and piping installed within the reactor
facility (including seismically-induced breakage), actuation of fire protection
systems, overflow or sloshing of the water in the spent fuel pool or spent fuel pit.
B

“Design so that the safety of the reactor facility is not impaired” in these regulations
refers to the ability to bring the reactor to hot shutdown, continue to cold shutdown,
and maintain confinement functions of radioactive material. If the plant is in a
shutdown condition, to the plant must be able to continue to maintain suchconditions when internal flooding is assumed to occur. For the spent fuel pool orspent fuel pit, the capability to maintain pool cooling and water supply to the poolmust be preserved.

122. Common technical requirements for reactor facilities(5) Design considerations for fire[Basic requirement]
Reactor facilities shall be designed considering protection measures such as preventionof fires, fire detection and suppression, and mitigation of impacts of fires so the safetyof the reactor facilities is not impaired by fires. The protection measures shall be
designed so as not to impair the safety functions of structures, systems, and components
important to safety due to failure or spurious actuation of the protection measures.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 5)[Requirement Details]
A. “Design considering protection measures such as prevention of fires, fire detection
and suppression, and mitigation of impacts of fires” refers to the design that complies
with separately defined requirements (※).
((※) Assessment guide is to be developed by the Nuclear Regulation Authority
referencing the US and other specification rules.)13

2.Common technical requirements for reactor facilities(6) Design considerations for environmental conditions[Basic requirement]
Structures, systems, and components with safety functions shall be designed to comply
with all environmental conditions for which the safety function is requred.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 6)[Requirement Details]
A. “All environmental conditions for which the safety function is required” refers to all
the environmental conditions to which the structures, systems, and components may
be exposed, and for which this equipment is expected to be operable during normal
operation, abnormal transients during operation, and during design basis accidents.

14

2.Common technical requirements for reactor facilities(7) Design considerations for common use[Basic requirement]
In principle, among structures, systems, and components with safety functions ofparticular importance shall not be shared or interconnected between two or more unitsof reactor facilities. However, this shall not apply if safety is enhanced through shareduse or interconnections.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 7)[Requirement Details]
A Items applicable under “among structures, systems, and components with safetyfunctions of particular importance” shall be determined based on Regulatory Guide
for Reviewing Classification of Importance of Safety Functions for Light Water
Nuclear Power Reactor Facilities.
B“If safety is enhanced” refers to cases in which consideration is given to benefits
resulting from shared use. Nevertheless, the technical requirements for each of the
facilities to be shared must be met. For example, control rooms can be designed tobe commonly used by the two units at a twin unit plant to enable the share ofoperators as long as habitability requirements are met.

C

“Common use” refers to using the same structures, systems, and components at two
or more reactor facilities.

D“Interconnection” refers to connection of systems or components between two or
more reactor facilities.

15

2. Common technical requirements for reactor facilities(8) Design considerations for operator manipulations[Basic requirements]
Reactor facilities shall be designed to take appropriate measures to prevent erroneous
operations by operators. The safety equipment constituting the reactor facility shall be
designed so that the operators can easily operate under environmental conditions inwhich operation is required.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 8)[Requirement Details]
A “Design taking into account appropriate measures” refers to the design features thatincorporate ergonomics such as: considerations for the location of panels andoperability of tools and valves, consideration so the conditions of reactor facility
can be accurately and quickly understood through instrument indications and alarmindications, and considerations so errors in maintenance and inspection will be lesslikely. In addition, it also refers to design that ensure necessary safety functions
without expecting operator actions up to a certain period of time after theoccurrence of an abnormal transient during operation or design basis accident.
B“Design so that operators can easily operate” refers to the designs that allow
operators to easily operate equipment even assuming environmental conditions due
to an abnormal event (for example, aftershocks) and environmental conditions thatare likely to occur simultaneously with other abnormal conditions assumed for thefacility.

16

2. Common technical requirements for reactor facilities(9) Design considerations for reliability[Basic requirement]
1

Structures, systems, and components with safety functions shall be designed toensure sufficiently high reliability and to allow it to be maintained corresponding to
the classification of importance of such safety function.

2

For systems with safety functions of particular importance, it shall be designed toachieve the safety function of the system even when offsite power is unavailable inaddition to assuming a single failure of a component that constitutes the system.

3

Therefore, the system in the above paragraph shall be designed with redundancy ordiversity and independence considering its structure, operation principles, andnature of safety function it fulfills.

(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 9)[Requirement Details]
A. “Ensure sufficiently high reliability corresponding to the classification ofimportance of such safety function” and “systems with safety functions of particularimportance” shall be stipulated separately based on “Regulatory Guide for
Reviewing Classification of Importance of Safety Functions for Light Water Nuclear
Power Reactor Facilities.”
B. “Single failure” can be separated into a single failure of active equipment and asingle failure of passive equipment. For systems with safety functions of particularimportance, it is necessary to design so that the prescribed safety functions areachieved even when postulating either a single failure of active equipment in the
short-term or single failure of active equipment or an assumed single failure ofpassive equipment in the long-term.
C. The boundary between short and long terms shall basically be 24 hours, and, if
operation mode is switched, that timing shall be the boundary between short andlong terms. For example, switching of the operating mode for PWRs would beswitching from injection mode using emergency core cooling system or containment

17

heat removal system to recirculation mode.
D. For safety function assessment in the long term that should postulate either a single
failure of active equipment or an assumed single failure of passive equipment as
indicated above, if it is certain that the single failure can be eliminated or remedied
within a time period that would not hinder safety even under the severest assumed
conditions, it is acceptable not to postulate this single failure.
E. If it is possible to rationally explain that the possibility of occurrence of a single
failure is extremely low, or if it can be confirmed through safety analysis and othermethods that there is an alternative to that function using other systems even in casesystem functions are lost when postulating a single failure, requirements for
redundancy shall not apply to the relevant component.

18

2. Common technical requirements for reactor facilities(10) Design considerations for testability[Basic requirement]
Structures, systems, and components with safety functions shall be designed to allow
testing and inspection (hereafter “testing”) during reactor operation or shutdown using
the appropriate methods corresponding to the classification of importance of the safetyfunction to confirm its integrity and capability.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 10)[Requirement Details]
A. “Appropriate methods” refer to the case when testing or inspection using actual
system is inappropriate and use of bypass systems for testing is allowed.
B. “Testing” shall be according to the following items:(a) Structures, systems, and components with safety function in standby condition
during reactor operation may be tested periodically during operation. However,
if testing during operation has a major impact on operation, this shall not apply.
In addition, testing can be conducted independently for individual systems andcomponents with redundancy or diversity. “Periodical testing during operation”
shall include tests stipulated in “Ordinance of Establishing TechnicalRequirements (Standards) for Nuclear Power Generation Equipment” (Ministryof International Trade and Industry Ordinance No. 62 (planned to be revised as
Nuclear Regulation Authority Rules).
(b) Regarding the functional test of each channel of safety protection systems
during operation, even when conducting the test, the safety protection system
function itself shall be maintained and any unnecessary operation of the reactor
shutdown system, emergency core cooling system or others shall not occur atthe same time.
(c) “Periodical testing during reactor shutdown” shall include tests stipulated by thelaws and regulations related to Reactor Regulation Law.
C. For the facilities listed in the left column in the table below, the requirements in theright column shall be met.

19

Structures, systems, components

Requirements

Reactivity control system

Design allows testing

Reactor coolant pressure
boundary

Design allows testing and inspection while reactor
is in service

System to remove residual heat

Design allows testing

Emergency core cooling system

Design allows testing and inspection periodicallyand testing and inspection can be conducted foreach system independently to check that integrity
and diversity is maintained

System to transport heat toultimate heat sink

Design allows testing

Reactor containment vessel

Design allows periodical leak rate test of theoverall reactor containment vessel using theprescribed pressure
Testing can be conducted for leaks from important
areas such as penetrations for cables and piping andaccess ways

Reactor containment vessel
isolation valve

Periodical operation test of the reactor containment
vessel isolation valve can be conducted and leaktests of major valves can be conducted

Reactor containment vessel heatremoval system

Design allows testing

Systems to control containment
facility atmosphere

Design allows testing

Safety protection system

In principle, the design allows periodical testing
during reactor operation and each channel can betested independently to check that its integrity andredundancy is maintainedElectrical systems

Electrical systems related to safety functions ofparticular importance shall be designed to allow
periodical testing and inspection of the important
portions of the system in an appropriate manner.

Fuel storage and handlingfacilities

Structures, systems, and components with safetyfunctions shall allow periodical testing andinspection in an appropriate manner.

202. Common technical requirements for reactor facilities(11) Design considerations for telecommunication systems[Basic requirement]
1

The reactor facility shall have telecommunication facilities and alarm systems inplace to provide proper instruction to all of the people at the nuclear power stationin case of a design basis accident.

2

The telecommunication facilities to offsite locations and telecommunication lines
for data transfer facilities shall be dedicated lines and shall be designed withdiversity.

3

The telecommunication facilities used between onsite locations shall be designedwith diversity.

(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 45)[Requirement Details]
A “Telecommunication facilities” refers to the facilities that allow communicationsuch as providing verbal instructions on operation, work, or evacuation from themain control room to personnel on locations inside and outside of the building.
B“Data transfer facilities” refers to the facilities to transfer necessary data fromonsite (main control room or other location) to off-site emergency response support
system (ERSS).

C“Telecommunication lines shall be dedicated lines and shall be designed withdiversity” refers to the design of communication lines with diversity incommunication methods (for example cables and wireless). This includes lines thatcan be used without limitations such as congestion. They include satellite-specific
IP phones and other dedicated telecommunication lines developed independently by
the reactor licensee or telecommunication lines dedicated for special customers
provided by the power and communication operator.

21

2. Common technical requirements for reactor facilities(12) Design considerations for evacuation routes[Basic requirement]
1

Reactor facilities shall be designed with evacuation lighting equipment that willremain functioning when normal lighting power supplies are lost and with safety
evacuation routes with simple, clear, and lasting signs.

2

Reactor facilities shall have lighting and dedicated power supply separate from
evacuation lighting to allow for work activities in case field work arises for accident
response.

(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 46)[Requirement Details]
A “Reactor facilities shall have lighting and dedicated power supply to allow for work
activities and field work required for accident response” refers to the need to havelighting systems to enable the work activities required for accident response in thereactor facility at any time of the day or night, or at any location. In terms of theemergency of the field work, it is acceptable to consider the use of temporary
lighting (portable) as time allows.

22

3. Individual systems within the reactor facility(1) Core, etc.
[Basic requirements](Core)
1 The core shall be designed in combination of the functions of the reactor coolingsystems, reactor shutdown systems, reactivity control systems, instrument control
systems and safety protection systems to ensure that allowable design limit of fuelis not exceeded during normal operation or abnormal transients during operation.
2 The composition elements of the core excluding fuel rods, as well as composition
elements in the vicinity of the core within the RPV, shall be designed to ensure safe
reactor shutdown and core cooling during normal operation, abnormal transientsduring operation, or design basis accidents.
(Fuel)
3 Fuel assemblies shall be designed to ensure integrity is not lost, even when
considering factors which could conceivably occur within the reactor during its
period of usage.
4 Fuel assemblies shall be designed to prevent occurrence of excessive deformation
during transport or handling.
(Reactor characteristics)
5 The core and relevant systems shall be designed to possess specific output control
characteristics, and be able to easily control any output fluctuation that may occur.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 11, 12, 13)[Requirement Details](Core)A Allowable design limits of fuel shall be set using factors such as fuel pellet
maximum temperature, fuel cladding pipe maximum temperature, maximum heat
flux, minimum critical heat flux, minimum critical power ratio, fuel pellet
maximum enthalpy, and fuel cladding maximum deformation as bases fordetermination.

23

B

Specific methods of the evaluation shall be as per the "Power generating light water
reactor facility reactivity insertion event evaluation policy (determined by Nuclear
Safety Commission of Japan on Jan. 19, 1984, partially revised on Aug. 30, 1990)."(Fuel)C "Factors which could conceivably occur" refer to the factors such as changes inpressure or temperature, chemical effects, static or active load, fuel pellet
deformation, and composition of gas sealed within fuel rods due to the difference
between internal and external pressure of fuel rods; as well as irradiation or load on
fuel rods and other materials.
D"Design to ensure integrity is not lost" refers to the design which ensures functions
such as the confinement function of fuel cladding, as well as insertability andgeometries of control rods maintained during both normal operation and abnormaltransients during operation for the prescribed operation period.

ESpecific methods of the evaluation shall be as per the "Power generating light water
reactor fuel design method,” (Approved by Nuclear Safety Commission of Japan on
May 12, 1988)."(Reactor characteristics)
F "Possess specific output control characteristics" refers to the reactivity feedback
effects (comprising of the Doppler coefficient, moderator temperature coefficient,moderator void coefficient, pressure coefficient, etc.) to control output in a
responsive manner for all foreseeable scopes of operation and to prevent or mitigate
fuel damage due to excessive changes in reactor output.
G"Easily control any output fluctuations that may occur" refers to the sufficientattenuation capability to prevent allowable design limit of fuel from being exceededor ability to control output fluctuations.

24

3. Individual systems within the reactor facility(2) Reactivity control systems and reactor shutdown systems[Basic requirements](Reactivity control systems)
1 Reactivity control systems shall be designed to maintain stable operation byadjusting foreseeable reactivity changes that are expected to take place during
normal operation.
2

Reactivity control systems shall be designed so that the maximum reactivity worth
and reactivity insertion rate of control rods will not cause damage to the reactor
coolant pressure boundary in case of a postulated reactivity insertion event, andalso ensure that destruction of the core, core support structures, or RPV internal
structures which would impair core cooling do not occur.

3

4

5

6

Reactivity control systems shall be designed to have two independent systems atleast to bring the core subcritical from a hot standby or hot operation state, and also
maintain subcriticality in a high temperature state.
Among the independent systems constituting the reactivity control systems, at least
one system shall be designed to bring the core subcritical in a high temperaturestate during normal operation or abnormal transients during operation without
exceeding allowable design limit of fuels, and also maintain subcriticality after atransient in a high temperature state has been terminated until Xenon decay allows
addition of reactivity.
Among the independent systems constituting the reactivity control systems, at least
one system shall be designed to bring the core subcritical while in a lowtemperature state, as well as maintain subcriticality in a low temperature state.
Among the independent systems constituting the reactivity control systems, at least
one system shall be designed to bring the core subcritical during design basis
accident. Among the independent systems constituting the reactivity control
systems, at least one system shall be designed to maintain core subcriticality.

(Reactor shutdown systems)
7 Reactor shutdown systems by way of control rods shall be designed to bring thecore subcritical in a high temperature state, even if a single control rod with thehighest reactivity worth (or a cluster of control rods when the concerned control rod
belongs to the same hydraulic control unit) has been completely withdrawn out of
the core and cannot be inserted. Reactor shutdown systems consisting of control

25

rods shall be designed to bring the core subcritical in a low temperature state, in
combination with the reactivity control systems if necessary, even if a single
control rod with the highest reactivity worth (a cluster of control rods when theconcerned control rod belongs to the same hydraulic control unit) has been
completely withdrawn out of the core and cannot be inserted.
※The testability shall be summarized in the common matters.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 14, 15, 16, 17, 18)[Requirement Details]
A. Evaluation of the "control rod maximum reactivity worth" may take into
consideration the effects of equipment installed to control reactivity value, such as
those limiting the extent of control rod insertion or positions depending on reactor
operation status.
B. "Foreseeable reactivity insertion events" refer to the events where abnormal
reactivity is introduced into the reactor. These are as stipulated in the "Regulatory
Guide for Reviewing Safety Design of Light Water Nuclear Power Reactor
Facilities " and "Guideline for Evaluation of Reactivity Insertion Events at Light
Water Nuclear Power Reactor Facilities"
C. "Maintain subcriticality in a high temperature state" refers to maintaining
subcriticality in the period after a transient has been terminated until reactivity isadded due to Xenon decay. The actions of other systems may be relied upon or
expected when maintaining subcriticality for greater lengths of time after thisperiod.
D. "Ability of bring the core subcritical in a low temperature state, and maintainsubcriticality in a low temperature state" refers to compensating for the reactivity
added due to Xenon decay or reactor coolant temperature changes during hightemperature subcriticality, while also achieving and maintaining low temperature
subcriticality.
E. The control rod systems and soluble poison systems currently used in light water
reactors (standby liquid control system for BWR, standby boric acid injection
systems as part of chemical and volume control system for PWR) can be considered
to be reactivity control systems which satisfy Item 3 above when looking at their26

functions.
F. The abilities of reactivity control systems during design basis accident may take thecontributions of systems which possess reactor shutdown ability into consideration
if their operation can be expected. An example would be the reactivity control
systems working in combination with the emergency core cooling system during
PWR main steam pipe rupture to induce subcriticality in the core and maintain coresubcriticality.
G. Regarding the equipment included in the reactor shutdown systems or reactivity
control systems, the control rod/chemical and volume control systems are bothincluded in the reactor shutdown systems or reactivity control systems for PWR,
while the control rod and SLC systems are both included in the reactor shutdown
systems or reactivity control systems for BWR. The reactor recirculation flow
control system is included in the reactivity control systems.

27

3. Individual systems within the reactor facility(3) Reactor coolant pressure boundaries[Basic requirements]
1. Reactor coolant pressure boundaries shall be designed to ensure its integrity during
normal operation, abnormal transients during operation, or DBA.
2. Piping systems connected to the reactor coolant system shall be designed to haveisolation valves in principle.
3. Reactor coolant pressure boundaries shall be designed so as not to show any brittle
behavior during normal operation, abnormal transients during operation, or DBA,
and not to cause sudden propagative fractures.
4. Reactor coolant pressure boundaries shall be designed to ensure that, in the event ofreactor coolant leakage from the reactor coolant pressure boundary, leak can beswiftly and accurately detected.
※The reliability and testability are to be summarized in the common matters.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 19, 20, 21, 22)[Requirement Details]
A. The reactor coolant pressure boundary refers to the equipment or piping within thescope covered below.
(a) RPV and associated components (components directly attached to the RPV, CRDM
housing, etc.).
(b) Equipment and piping comprising the reactor cooling system. For PWR, this refers
to the primary coolant pump, steam generator channel head, tubesheet and tubes,
pressurizer, primary cooling system pipes, and valves. For BWR, the scope ofequipment covered includes the main steam pipes and feedwater pipes up to thesecondary isolation valves as seen from the reactor side.
(c) Connection pipingi) Including the pipes that are equipped with valves which are normally open andclosed in case of an accident up to the secondary isolation valves as seen fromthe reactor side.
ii) Including the pipes that are equipped with valves which are normally closed
and closed in case of an accident up to the secondary isolation valve as seen
28

from the reactor side.
iii) as Also including the pipes of the emergency core cooling system which areequipped with valves that are normally closed in and opened when reactor
coolant is lost as stipulated in i) above.
iv) "Isolation valves" above refers to the automatic isolation valves, check valves,normally locked shut-off valves, and remote control shut-off valves.
B. "Design which ensures integrity" refers to designs where the functions of thereactivity control systems, reactor cooling systems, instrumentation and control
systems, safety protection systems, and safety valves are able to prevent sudden
cooling/heating or abnormal pressure increase of the reactor coolant pressure
boundary. The reactor coolant pressure boundary shall be designed to ensure that it
can sufficiently withstand such temperatures or pressure changes, and incorporate
design considerations to minimize abnormal reactor coolant leakage or damage tothe reactor coolant pressure boundary.
C. "Design that is provided with isolation valves in principle" refers to the design
where sufficient consideration is given to the objective of use and conditions ofpiping systems during normal operation, and appropriate isolation valves have been
installed. The purpose thereof is to terminate the loss of reactor coolant in the eventthat abnormal leakage takes place at piping systems which comprise the reactor
coolant pressure boundary, and specifically occurs between the piping systems
which are connected to the reactor cooling system and the piping systems are notconnected. The phrase "as a general rule" here refers to piping where measurement
or sampling vital to reactor safety are performed, and assumes that the leakage
which takes place at these pipes is so minor as to be sufficiently allowable. Piping
which does not comprise the reactor coolant pressure boundary shall not haveisolation valves installed.
D. Specific methods of the evaluation shall be as per the "Guideline for Evaluation of
Reactivity Insertion Events at Light Water Nuclear Power Reactor Facilities.
(Determined by Nuclear Safety Commission of Japan on Jan. 19, 1984, partiallyrevised on Aug. 30, 1990)"

29

3. Individual systems within the reactor facility(4) Reactor cooling system① Reactor coolant makeup system[Basic requirements]
The reactor coolant makeup system shall be designed to have the ability to feed coolant
at an appropriate flow rate so that the reactor coolant inventory can be restored even in
the event of a minor reactor coolant leakage.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 23)[Requirement Details]
A. The "reactor coolant makeup system" refers to the system which feeds the reactor
cooling system with reactor coolant (the CRD hydraulic system and reactor
isolation cooling system (excluding feedwater system) for BWR, and the systems
feeding coolant by utilizing charge pumps for PWR).
B. "Minor reactor coolant leakage" refers to the reactor coolant leakage from cracking
and form seals of valves and pumps constituting the reactor coolant pressure
boundary.

30

3. Individual systems within the reactor facility(4) Reactor cooling system② RHR system[Basic requirements]
1. The RHR system shall be designed to have the ability to remove fissile productdecay heat and other residual heat from the core to prevent the allowable design
limit of fuel and reactor coolant pressure boundary design conditions being
exceeded during reactor shutdown.
2. The RHR system shall be designed to achieve its safety function in the event thatexternal power sources are not available, in addition to an assumed single failure of
the equipment which constitutes the RHR system.
※The reliability and testability are to be summarized in the common matters.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 24)[Requirement Details]
A. The "RHR system" refers to the system designed to remove residual heat in the eventthat heat removal by the main condenser fails (reactor core isolation cooling system,
RHR system, HPCS system, and automatic depressurization system for BWR; steam
generator, main steam relief valves, main steam safety valves, auxiliary feedwaterequipment, and residual heat removal system for PWR).In addition, systems are inplace to depressurize the reactor cooling system for BWR (main steam safety relief
valves) and PWR (pressurizer relief valves).
B. "Other residual heat" refers to the heat stored within areas such as the core,equipment, and materials such as the reactor cooling system, reactor coolant, andsecondary coolant (for PWR) during normal operation.

31

3. Individual systems within the reactor facility(4) Reactor cooling system③ Emergency core cooling system[Basic requirements]
1. The emergency core cooling system shall be designed to prevent extensive fueldamage in the event LOCA caused by assumed piping rupture and other events, andto minimize the interaction between fuel cladding metal and water.
2. The emergency core cooling system shall be designed to achieve its safety functionin the event external power supplies are not available in addition to an assumed
single failure of equipment which constitutes the system.
※The reliability and testability are to be summarized in the common matters.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 25)[Requirement Details]
A. Specific methods of the evaluation shall meet the "Guideline for Evaluation of
Performance of Emergency Core Cooling System of Light Water Nuclear Power
Reactor Facilities (determined by Nuclear Safety Commission of Japan on Jul. 20,
1981, partially revised on Jun. 11, 1992)."
B. "assumed piping rupture" refers to "assumed LOCA accidents" described in the"Guideline for Evaluation of Performance of Emergency Core Cooling System ofLight Water Nuclear Power Reactor Facilities"
C. "Piping ruptures etc." shall include accidents where LOCA is caused by e.g. stuck
open of relief valves which doesn’t accompany actual physical break.
D. Decisions regarding "sufficiently minor amount" shall be made according to the"Guideline for Evaluation of Performance of Emergency Core Cooling System ofLight Water Nuclear Power Reactor Facilities ".

32

3. Individual systems within the reactor facility(4) Reactor cooling system④System to transfer heat to the ultimate heat sink
[Basic requirements]
1. The system to transfer heat to the ultimate heat sink shall be designed to transfer
heat generated or accumulated in structures, systems or equipment having safetyfunctions of particular importance to the ultimate heat sink.
2. The system to transfer heat to the ultimate heat sink shall be designed to achieve its
safety functions event if external power sources are not available in addition to anassumed single failure of equipment which constitutes the system.
3. The system to transfer heat to the ultimate heat sink shall be designed taking into
account the physical protection against design basis tsunamis, flooding, missiles,
and all other external human events.
※The reliability and testability are to be summarized in the common matters.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 26)[Requirement Details]
A. "Ultimate heat sink" refers to the seas, rivers, ponds, lakes, and atmosphere.
B. "System to transfer heat to the ultimate heat sink" refers to the system to transfer
heat from the emergency core cooling system and RHR system (e.g., reactor
auxiliary component cooling equipment, reactor auxiliary component coolingseawater equipment) to the ultimate heat sink.

33

3. Individual systems within the reactor facility(4) Reactor cooling system⑤Steam turbines[Basic requirements]
1. Steam turbines and their associated components shall be designed so that they will
not cause any adverse effect on the safety of reactor facilities.
2. Steam turbines and their associated components shall be designed to monitor
parameters necessary to prevent reactor facility safety from being impaired bydamage to turbines.
(※Equipment requiring establishment of new standards due to unification with
Electricity Business Act)
[Requirement Details]
A. "Design not causing any adverse effect on the safety of reactor facilities" refers to
the use of materials with resistance against chemical and physical effects underassumed environmental conditions, and to the sufficient structural strength including
countermeasures against steam turbine vibration and over speed to ensure the safetyof the reactor facility is not affected in the event of damage to steam turbines.

34

3. Individual systems within the reactor facility(5) Reactor containment vessel① Reactor containment vessel[Basic requirements](Functions of the reactor containment vessel)
1 The reactor containment vessel shall be designed to withstand loads(pressure,temperature, dynamic load) arising from an anticipated event as well as relevant
seismic loads, and to function in combination with an appropriate isolation function
to keep the amount of leakage within a specified limit.
※The reliability and testability are to be summarized in the common matters.
(Preventing damage to the reactor containment vessel boundary)
2 The reactor containment vessel boundary shall be designed not to exhibit brittle
behavior and develop any quickly propagative failure during normal operation,
maintenance, testing, abnormal transient and design basis accident.
(Isolation function of the reactor containment vessel)
3 The pipes that penetrate through the walls of the reactor containment vessel shall be
provided with containment isolation valves except for those pipes used formeasurement or sampling important to the reactor safety and CRDM hydraulicpipes for which leakage through the pipe walls is small enough to be allowable.
4

The containment isolation valves to be installed on main pipe systems shall be
designed to automatically and reliably close in the event of a design basis accident
which requires the secured isolation function except for the pipes in the systems
needed to bring the accident under control.
※The reliability and testability are to be summarized in the common matters.

(Containment isolation valves)
5 Containment isolation valves shall be installed close to the reactor containment
vessel.
6

Containment isolation valves shall be installed in the following manners:
a For the pipes that either open inside of the reactor containment vessel orconnected to the reactor coolant pressure boundary, and are not closed on
the outside of the reactor containment vessel, install one valve on the inside

35

b

c

d

and another valve on the outside of the reactor containment vessel. If it isdifficult to install isolation valves for physical reasons or due toenvironmental conditions, two isolation valves may be installed either on
the inside or the outside of the reactor containment vessel provided thatsuch installation is shown to be valid.
For the pipes other than those described in the preceding paragraph, thatare closed either on the inside or the outside of the reactor containment
vessel, install one isolation valve on the outside of the reactor containment
vessel. Alternatively, one isolation valve may be installed on the insideprovided that such installation is shown to be valid.
Notwithstanding the provisions of the two preceding paragraphs, for thepipes that have a rupture disk, it is allowed to install one normally closed
isolation valve, in addition to the rupture disk, either on the inside or theoutside of the reactor containment vessel.
Containment isolation valves shall not lose its isolation function even when
their source of drive force is lost after their closure.

(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 28-31)[Requirement details]
A "Anticipated event" refers to an event anticipated for determining the validity ofreactor containment vessel design. It encompasses the most severe conditions
against relevant parameters out of evaluated parameters that could hinder theassurance of containment vessel functions such as pressure / temperature increase,dynamic load development, combustible gas generation, and concentration ofradioactive materials. Specific details are defined in the Regulatory Guides for
Reviewing Safety Evaluation of Light Water Nuclear Power Reactor Facilities(adopted by the Nuclear Safety Commission on August 30, 1990 and partiallyrevised on March 29, 2001).
B"Containment isolation valves" refer to automatic isolation valves (including checkvalves designed to deliver a sufficient isolation function at the time of a designbasis accident), normally-locked shut-off valves and remote-controlled shut-off
valves. "Check valves designed to deliver a sufficient isolation function at thetime of a design basis accident" refer to check valves designed to sustain theirisolation function by way of gravitational force, etc., even in the loss of all counter36pressure to the applicable check valve following damage to the applicable pipe
system penetrating through containment vessel walls either on the inside or theoutside of the primary containment vessel.
C"Main pipe systems" refer to pipe systems that must have containment isolation
valves installed and could cause an unallowable level of leakage from thecontainment vessel if left in the state of normal operation, excluding those designed
to have containment isolation valves closed in high temperature operation.

D"Function to automatically and reliably close" refers to the function of
automatically closing in response to a reactor containment vessel isolation signal
from the safety protection system, and reducing the leakage of radioactive materials
from the reactor containment vessel in combination with isolation barriers otherthan containment isolation valves even in the event of a single failure when off-site
power is not available.

E"Except for the pipes in the systems needed to bring the accident under control"refers to the exclusion of the pipes in the Emergency Core Cooling System, etc. that
do not have to be closed in response to an automatic isolation signal so as not tocompromise the safety functions expected of the applicable system. However,these pipes must not cause the loss of the reactor containment vessel's isolation
function.

F

The containment isolation valves that are automatically closed shall take into
account the cancellation of isolation to allow necessary actions to be taken after an
accident.

G"Pipes that are not closed on the outside of the reactor containment vessel" refer tothe pipes that could form a channel for discharging an unallowable level ofradioactive materials from the reactor containment vessel atmosphere to the outside
if not isolated, in the event of a design basis accident.

H"Installation of a rupture disk" can occur only when it is shown not to adversely
affect the safety functions of sever accident management equipment, which is to be
separately installed. If installed, a rupture disk may be opened at a pressure
setting sufficiently below the containment vessel's design pressure.

I

Specific evaluation is performed in accordance with the "Regulatory Guide for
Evaluating Dynamic Load on BWR Mark II Containment Pressure Suppression
Systems (adopted by the Nuclear Safety Commission on July 20, 1981 and partiallyrevised on August 30, 2000).
37

3. Individual systems within the reactor facility(5) Reactor containment vessel② Reactor containment vessel heat removal systems, systems controlling thecontainment atmosphere[Basic requirements](Reactor containment vessel heat removal system)
1 The reactor containment vessel heat removal system shall be designed to havesufficient functionality for reducing the pressure and temperature inside the reactor
containment vessel, generated from the energy released in the event of a designbasis accident.
2

The reactor containment vessel heat removal system shall be designed to achieve its
safety in the event that the external power sources are not available in addition to anassumed single failure of equipment constituting the system.
※The reliability and testability are to be summarized in the common matters.

3(Systems controlling the containment atmosphere)
The containment atmosphere purifier system must be designed to have the functionof lowering the concentration of radioactive materials, released into the atmospherein the event of a design basis accident.

4

The flammability control system shall be designed to control the concentration ofhydrogen or oxygen inside the reactor containment vessel, generated in the event ofa design basis accident, in order to maintain the integrity of the containment facility.

5

The containment atmosphere control system shall be designed to achieve its safety
in the event that the external power sources are not available in addition to anassumed single failure of equipment constituting the system.
※The reliability and testability are to be summarized in the common matters.

(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 32-33)[Requirement details]
A “Reactor containment vessel heat removal system” refers to the system thatsufficiently reduces the pressure and temperature inside the reactor containment

38

vessel in the event of a design basis accident.
Spray System and its heat removal systems.

This includes the Containment

B“Systems controlling the containment atmosphere” refer to the containment
atmosphere purifier system and flammability control system.

C“Containment atmosphere purifier system” refer to the emergency Gas Treatment
System, Filtration Recirculation and Ventilation System, Containment Spray
System, etc. in a BWR and the Annulus Air Recirculation System, Containment
Spray System, etc. in a PWR.

D“Controlling the concentration of hydrogen or oxygen” refers to keeping theatmosphere inside the reactor containment vessel inert or keeping the concentrationof hydrogen or oxygen below the combustible limit by means of hydrogen
recombiners or other methods as necessary.

39

3. Individual systems within the reactor facility(6) Instrumentation and control system① Instrumentation and control system[Basic requirements]
1 The Instrumentation and control system shall be designed to fulfill the following
requirements during normal operation and abnormal transients during operation:a All the parameters required for securing the integrity of the reactor core, reactor
coolant pressure boundary, containment vessel boundary, fuel storage facilities
and associated systems, shall be maintained and controlled within the assumed
range of fluctuation.
b The parameters listed in the preceding paragraph shall be monitored within theassumed range of fluctuation to facilitate necessary response.
2

The instrumentation and control system shall be designed to fulfill the following
requirements in the event of a design basis accident:a All the parameters required for identifying and countering accident conditions
shall be monitored in an environment anticipated in an accident over a
sufficient range and period.
b The reactor's shutdown state and core cooling state shall be monitored or
estimated based on at least two of these parameters.
c Readings of required parameters must be kept in records and archives.

(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 47)[Requirement details]
A "All the parameters required for securing the integrity" refer to in-core neutron flux,
neutron flux distribution, reactor coolant inventory, reactor coolant system'spressure / temperature / flow volume, reactor coolant quality, pressure / temperature/ atmospheric gas concentration in the primary containment vessel, and pool level /temperature at fuel storage facilities.
B"All the parameters required for identifying and countering accident conditions"refer to the pressure, temperature, hydrogen gas concentration, radioactive material
concentration, etc. in the atmosphere inside the containment vessel.

40

C"Required parameters" in Paragraph 2 Item 3 refer to items listed in Article 20
Paragraph 1 Item 1 and from Item 3 to Item 14 of the government directive defining
the technological standards concerning nuclear facilities for power generation.

D"Records and archives" refer to the state whereby necessary parameters "can bereferenced" after an event.

E

The requirements for the measurement and control systems in the event of a designbasis accident are as defined in the Regulatory Guide for Reviewing Radiation
Measurement during Accidents at Light Water Nuclear Power Reactor Facilities(adopted by the Nuclear Safety Commission on July 23, 1981 and partially revised
on September 19, 2006).

41

3. Individual systems within the reactor facility(6) Instrumentation and control systems② Safety protection systems[Basic requirements]
1

The safety protection systems shall be designed with redundancy so that the safety
protection functionality is maintained during normal operation, abnormal transient
during operation and a design basis accident even if a single device or channel
comprising the applicable system is removed.

2

The safety protection systems shall be designed to have channels comprising theapplicable system mutually separated to achieve each channel’s independence, sothat the safety protection function is maintained in normal operation, maintenance,
testing, and abnormal transient during operation and a design basis accident.

3

The safety protection systems shall be designed to detect an abnormal status at thetime of abnormal transient during operation, and automatically activating
appropriate systems including the reactor shutdown systems, so as to keep the fuelwithin its allowable design limit.

4

The safety protection systems shall be designed to detect an abnormal status in theevent of a design basis accident, and automatically actuate the reactor shutdown
systems and other necessary systems including engineered safety facilities.

5

The safety protection systems shall be designed to bring the reactor facility to a safe
state even in the loss of drive power source, system shutdown or any other adverse
state.

6

The safety protection systems shall be designed to take into account unauthorized
system breach from an external network and other cyber security issues.

7

The safety protection systems shall be designed to be functionally separated fromthe measurement and control systems, if they are partially shared, so that themeasurement and control systems would not disrupt the functionality of the safety
protection systems.
※The reliability and testability are to be summarized in the common matters.

42

(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 34-39)[Requirement details]
A “Channels” refer to arrays of components (resister, condenser, transistor, switch,
conductor, etc.) and modules (assemblies of components that are internallycommunicating) from a detector to the inlet of a logical circuit, required to generatea stand-alone signal for activating safety protection.
B“Having channels mutually separated” refers to a mechanism for preventing anadverse condition on one channel from inducing a similar adverse condition on
another channel, or safeguarding a channel from influence that could hinder its
safety functionality.

C

An example of the safety protection systems’ function in abnormal operationaltransient is to detect the abnormal state and activate the reactor shutdown systemand other relevant systems to initiate emergency shutdown, in order to prevent
excessive reactor output and sudden output rise.

D“Loss of drive power source, system shutdown or any other adverse state” refers to
the shutoff of a safety protection system’s logic circuit due to the air loss of
instrumentation or some other cause. An adverse state includes environmental
conditions, but the state that needs to be taken into account is determined on acase-by-case basis for individual designs.

E“To bring the reactor facility to a safe state” refers to the reactor facility settling andremaining in a safe condition even when a safety protection system fails, or thereactor facility maintaining a state with no safety issues even if a safety protection
system fails.

F“Design that takes into account cyber security issues” refers to a design approachthat prevents unauthorized actions and changes via physical hardware separation,functionality separation, and preventing computer viruses on the stages of system
introduction, update, and testing.

G“Will not lose the functions of the safety protection systems” means, even if asingle failure, erroneous operation or single removal from the service occurred inany component or channel of the connected instrumentation and control system, the43

portions of the safety protection system that immune to such failure/removal would
satisfy the basic requirements 1 to 6 for the safety protection systems.

44

3. Individual systems within the reactor facility(6) Instrumentation and control systems③Control room, etc. (excluding habitability)[Basic requirements](Control room)
1 The control room shall be designed to monitor the operation status and main
parameters of the reactor and its associated facilities.
2 The control room shall be designed to be able to identify the status outside thereactor facility.
3 The control room shall be designed to enable quick manual operation for assuringsafety if such operations are required.
(Reactor shutdown function from outside the control room)
4 The reactor facility shall be designed to have the following functions so that thereactor can be shut down from an appropriate location outside the control room:a Being able to bring the reactor to a rapid hot shutdown with necessary
instrumentation and control systems to maintain the reactor facility in a safe
stateb Being able to bring the reactor to a cold shutdown by way of following
appropriate procedures(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities41-42)[Requirement details]
A "Able to monitor main parameters" refers to the ability to monitor, from the control
room, the parameters that are subject to monitoring as [Basic requirements] for the
instrumentation and control systems and need to be monitored continuously.
B"Designed to be able to identify the status outside the reactor facility" refers to theability to identify, from the control room, any natural phenomena, etc. that could
affect the reactor facility.

C"Quick manual operation" refers to the operation for shutting down a reactor andensuring the cool-down of the reactor after its shutdown.

45

D"The reactor can be shut down from an appropriate location outside the controlroom" means that some countermeasures are in place when personnel cannot
approach the control room for some reason.

E"Bringing the reactor to a rapid hot shutdown" refers to the ability to shut down areactor immediately, remove residual heat, and safely maintain the state of hot
shutdown.

46

3. Individual systems within the reactor facility(6) Instrumentation and control systems④ Control room, etc. (habitability)[Basic requirements]
The control room shall be designed to have a fire protection mechanism, shield facilities
so that personnel can access or stay in the control room even in the event of a designbasis accident to carry out accident response operations, and a ventilation system toprovide adequate protection against toxic gas and radioactive materials that could bedischarged in a fire or an accident.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 43)[Requirement details]
A "So that personnel can access or stay in the control room" means having an accessroute secured for personnel in charge of accident response operations to reach thecontrol room when an accident occurs, facilitating personnel's stay in the control
room for an appropriate period of time, and enabling the implementation of
exposure protection measures following accident response operations once theradiation level attenuates after a certain period of time, so as to allow replacement
personnel to approach the control room.

47

3. Individual systems within the reactor facility(6) Instrumentation and control systems⑤ Emergency response center[Basic requirements]
The reactor facility shall be designed so that the emergency response center for issuingnecessary orders/commands on countermeasures in the event of a design basis accident
can be installed on site.
(See the requirements for severe accidents for specific requirements.)(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 44)

48

3.Individual systems within the reactor facility(7) Electric systems① Basic requirements concerning the safety design of electric systems for the reactor
facility[Basic requirements]
1

The structures, systems and components with safety functions of particularimportance shall be designed to be able to receive power from both an off-site
power source (electric system) and emergency power source on site, with the power
supplies designed to secure and sustain a sufficiently high level of reliability when
they need electricity to fulfill their functions. Also, in order to ensure that theywould not lose required power supplies as a result of a fault in electric systemequipment such as a main generator, off-site power system, emergency on-site
power system, etc. or disruption to the off-site power (electric system), thesestructures, systems and components should be designed to detect an abnormal status
and prevent its expansion or propagation.

2

The off-site power system shall be connected to the reactor facility's electric system
via at least 2 transmission lines, which are connected to at least 2 separate,
independent substations or switchyards, wherein at least one of the transmission
lines must be physically separate from other lines. A nuclear power station thathas multiple reactor facilities shall be designed so that the reactor facilities would
not lose off-site power simultaneously even if any two of the transmission lines are
lost.

3

The emergency on-site power systems shall be designed to have sufficient capacityand functionality to ensure the following matters even if any one of the systems is
lost:a. Shutting down and cooling the reactor in the event of an abnormaltransient during operation without exceeding the allowable design limit forfuel or design conditions for reactor coolant pressure boundaryb. Cooling the core in the event of a design basis accident such as the loss ofreactor coolant, ensuring the integrity of the reactor containment vessel andsecuring the safety functions of other relevant systems and equipmentc. Ensuring that emergency on-site power facilities do not rely on shared use
between at least two reactor facilities49

4Emergency on-site AC power facilities shall be designed to continuously supply
required electricity in the event of the loss of off-site power for a cerain period oftime.
※The reliability and testability are to be summarized in the common matters.

(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 48)[Requirement details]
A "Power supplies designed to secure and sustain a sufficiently high level ofreliability" means that electric systems' bus is configured in view of systemseparation so as not to compromise the redundancy for the structures, systems andcomponents with safety functions of particular importance, and that individualcomponents comprising the electric systems are highly reliable to make it easy to
switch bus, for example, to receive power from the emergency on-site powersystem.
B"Off-site power source (electric system)" refers to an electric system outside thepower station's switchyard and does not include the applicable reactor facility's
main generator or the main generators of other reactor facilities within the same
nuclear power station.

C"Designed to detect an abnormal status and prevent its expansion or propagation"refers to a design that detects the short circuiting / grounding of devices in theelectric systems as well as low voltage / over voltage of bus and uses a circuit
breaker, etc. to isolate the fault location to localize the impact or limit its impact onother safety functions.

D"Off-site power system" refers to the off-site power source (electric system) and aseries of components for supplying electricity from the applicable reactor facility's
main generator to the reactor facility.

E"At least 2 separate, independent substations or switchyards" refer to at least 2
different substations or switchyards that are connected to a single substation or aswitchyard upstream of the electric system, so that the shutdown of one of thesesubstations or switchyards would not entirely halt power transmission on thetransmission lines connected to the nuclear power station.

50

F"At least 2 transmission lines" in the off-site power system shall be achieved by
combining lines that can send and receive power and lines dedicated to receiving
power, provided by establishing at least two lines connecting the electric system toemergency on-site power distribution facilities for receiving power from an off-site
power source. "Physically separate" refers to the mechanism of preventing
simultaneous transmission cut by laying transmission lines through multiple
transmission line towers to avoid the situation in that the collapse of a transmission
tower that carries all the transmission lines would result in simultaneoustransmission cut.

G

Switchyards and power transmission / receiving facilities at a nuclear power stationmust be built on the ground foundation that has sufficient support to resist uneven
subsidence or inclination, and use insulators, circuit breakers, etc. that are highly
earthquake resistant. These facilities shall be isolated or protected from the impact
of possible tsunami, with considerations given to salt damage.

H

In the case of a nuclear power station that has multiple reactor facilities, the off-site
power system shall be connected to the electric systems of each of the reactor
facilities via at least three transmission lines in a tie-line design so that the multiple
reactor facilities would not experience the loss of off-site power simultaneously
even if any two of those lines fail.

I“Emergency on-site power system” refers to facilities (emergency bus switch gear,
cables, etc.) supplying power to the equipment with safety functions of particularimportance, including emergency on-site power source facilities (e.g., emergency
diesel generators, batteries) and engineered safety features.

J“Loss of off-site power for a certain period of time” for emergency on-site AC
power supplies (emergency diesel generators, etc.) refers to the assumption of a
7-day loss of off-site power, during which the emergency diesel generators, etc.
must operate continuously to supply electricity. The facilities for storing the fuelfor the emergency diesel generators, etc. (seismic S class) shall be designed to havea capacity to store enough fuel required to operate them for 7 consecutive days on
site.

K

“Safety function of particular importance” is to be defined separately based on the“Review Guide for Classification of Safety Function Importance in Light Water
Nuclear Power Reactor Facilities”.

51

3. Individual systems within the reactor facility(7) Electric systems②Basic requirements concerning electrical facilities at a nuclear power station[Basic requirements]
1 Of electrical facilities at a nuclear power station, switchyards, large transformers, main
generators, etc. shall be designed considering electric circuits' electric insulation, open
circuit prevention, grounding measures, earthing measures, over-current measures, heat
resistance and mechanical impact caused by short-circuit current.
2 Compressed air equipment used in circuit breakers and gas-insulated circuit breakers
shall be designed to facilitate the monitoring and control of pressure used, sufficiently
withstand the pressure applied and have anti-corrosive property.
3 The rotating part of the main generators shall be designed to have sufficientmechanical strength. Of the main generators, those in the hydrogen cooling system
must be designed to prevent hydrogen leakage or air entry, detect any hydrogenleakage, sound an alarm in the case of leakage, stop the leakage and release the leakedhydrogen outside.
4 Lightning arresters shall be installed so that lightning would not damage electric
circuits' electric facilities.
(New)[Requirement Details]
A. "Electrical facilities at a nuclear power station" refer to electrical facilities for power
generation purposes, driven with nuclear energy (according to Article 106 of theElectricity Business Act), and represent equipment at a switchyard within a nuclear
power station (circuit breakers, line switches, lightning arresters, insulators, etc.),
large transformers for sending / receiving electricity to/from off-site power sources,
main generators, electric circuits that mutually connect these electrical facilities,
electric circuits connecting to off-site power sources, and security communications
system.

52

3.Individual systems within the reactor facility(8) Design considerations against station blackout[Basic requirements]
Reactor facilities shall be designed to shut down the reactor safely, cool it down after
shutdown, and secure the integrity of the reactor containment vessel in the event ofstation blackout that lasts for a certain period of time.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water
Nuclear Power Reactor Facilities Guide 27)[Requirement Details]
A To be prepared for station blackout (combination of the loss of off-site power andthe loss of emergency on-site AC drive power), emergency on-site DC power
supply shall be designed to serve as the source of power required for safe reactor
shutdown and subsequent cooling for a certain period of time.
B"Designed to shut down the reactor safely, cool it down after shutdown, and secure
the integrity of the reactor containment vessel" refers to the design of theemergency on-site DC power supply to have sufficient capacity to handle the power
load assigned to these facilities to maintain the functions associated with reactor
shutdown, subsequent reactor cooling, and securing the integrity of the containment
vessel.

53

3.Individual systems of a reactor facility(9) Radioactive waste treatment facilities[Basic requirements](Treatment facilities for radioactive gaseous waste and radioactive liquid waste)
1. The treatment facilities for radioactive gaseous waste and radioactive liquid waste,
generated during the operation of a reactor facility, shall be designed to sufficiently
lower the concentration and volume of radioactive materials discharged into thesurrounding environment.
2. The treatment facilities for radioactive liquid waste and associated facilities shall be
designed to prevent the leakage of liquid radioactive materials from these facilities ortheir discharge to the outside of the plant site.
(Treatment and storage facilities for radioactive solid waste)
3. The treatment facilities for radioactive solid waste, generated from a reactor facility,
shall be designed with considerations to prevent the possible dispersion of radioactive
materials.
4. The storage facilities for radioactive solid waste shall have sufficient capacity forstoring radioactive solid waste, generated from a reactor facility, and shall be
designed with considerations to prevent the spread of contamination attributable towaste.

(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 52-55)[Requirement Details](Treatment facilities for radioactive gaseous waste and radioactive liquid waste)
A. "Design to sufficiently lower the concentration and volume of radioactive materials
discharged" refers to the use of filtration, retention, attenuation, management, etc.
for gaseous waste treatment facilities, and filtration, evaporation, ion exchange,
retention, attenuation, management, etc. for liquid waste treatment facilities.
B. "Sufficiently lowering" refers to lowering radiation dose to the target level definedin the "Annual Dose Target for the public in the Vicinity of Light Water Power
Reactor Facilities" (adopted by the Nuclear Safety Commission of Japan on May 13,54

1975) <Note: 50 μSv/year> under the concept of ALARA (As Low As Reasonably
Achievable).
C. The evaluation of abovementioned dose target shall be conducted according to the"Regulatory Guide on the Assessment of Exposure Dose of the Public in Safety
Examination of Power Generating Light Water Reactors" (adopted by the Nuclear
Safety Commission of Japan on September 28, 1976).
D. The "treatment facilities for radioactive liquid waste" refer to facilities that separate
and collect radioactive liquid waste as well as radioactive waste in the liquid state
containing sludge and other solid matter, and apply filtration, evaporation, ion
exchange, retention, attenuation, management, and other appropriate processing
according to the properties of the waste liquid.
E. "Associated facilities" refer to buildings or areas for housing treatment facilities.
F. "Design to prevent the leakage of radioactive liquid materials from these facilities ortheir discharge to the outside of the plant site" is determined according to"Considerations and Basic Approach to the Safety Review of Radioactive Liquid
Waste Processing Facilities" (adopted by the Nuclear Safety Commission of Japanon September 28, 1981).
(Treatment and storage facilities for radioactive solid waste)
G. “Dispersion of radioactive materials” includes the spread of waste through theprocesses of crushing, compaction, incineration, and solidification.
H. The storage facilities for radioactive solid waste shall be capable of storing andmanaging the volume of radioactive solid waste generated at or transported into thereactor facility in the future.

55

3. Individual systems of a reactor facility(10) Fuel handling systems[Basic requirements]
1. The new and spent fuel storage and handling facilities shall be designed to meet thefollowing requirements:
a. Storage facilities shall have appropriate containment systems and air purification
systems.
b. Storage facilities shall have an appropriate storage capacity.
c. Handling facilities shall be able to prevent the fall of fuel assemblies during transfer
operation.
※ The testability is to be summarized in the common matters.
2. The storage facilities (excluding the cases where dry storage casks are used) andhandling facilities for spent fuel shall be designed to meet the following requirements
in addition to the requirements listed in the preceding paragraph:a. The facilities shall have appropriate shields for radiological protection.
b. The facilities shall have the systems for removing decay heat from spent fuel andtransfer heat to the ultimate heat sink, as well as associated systems for purification.
c. The facilities shall be able to prevent significant reduction in coolant inventory andcarry out appropriate leakage detection.
d. The facilities shall be able to maintain their safety functions even in an anticipated
event during the handling of fuel assemblies, such as dropping of the assemblies or
falling of a heavy item.
3. The storage facilities for spent fuel (only for the cases where dry storage casks areused) shall be designed to meet all the following requirements in addition to therequirements listed in Paragraph 1 (excluding air purification systems if the lid fordry storage casks are not to be opened in the applicable facility, and if thecontainment of radioactive materials can be secured only with the use of the dry
storage casks):a. The facilities shall have appropriate shields for radiological protection.
b. The facilities shall be able to remove decay heat properly.
c. The facilities shall be able to properly contain radioactive materials included in spent
fuel, and monitor their functions appropriately.

56

4.

The storage facilities and handling facilities for fuel shall be designed to prevent
criticality.

5.

The storage and handling facilities for new and spent fuel shall be designed to beable to measure the water level and temperature of spent fuel storage facilities andradiation level of the location of fuel handling, detect abnormal readings, andinform workers of abnormal readings reliably or address them automatically.
Furthermore, they shall be designed to monitor multiple parameters even whenoff-site power is not available.

(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 49-51)[Requirement Details]
A. “Dry storage casks” refer to containers in which spent fuel is loaded with inert gas
for storage, consisting of the main cask unit, a (double) lid, a basket, etc.
B. “Informing workers of abnormal readings” means the readings can be monitoredfrom the control room even if access to the location of fuel handling is restricted due
to an abnormal state.
C. The design of dry storage casks is verified according to “Dry cask storage of spent
fuel at nuclear power stations” (adopted by the Nuclear Safety Commission of Japanon August 27, 1992 and partially amended on September 29, 2001).

57

3.Individual systems of a reactor facility(11) Radiation control① Surrounded radiological protection facilities (during normal operation)[Basic requirements]
The reactor facility shall be designed to sufficiently lower the space dose rate insurrounding areas during normal operation, caused by direct gamma rays and skyshine
gamma rays.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 56)[Requirement Details]
A. “Sufficiently lowering” means the facilities shall be designed and managed to keep
the air kerma no more than 50 micro gray per annum based on the concept of
ALARA and according to the “Dose Evaluation for Members of the Public during
Safety Review of Light Water Nuclear Power Reactor Facilities” (adopted by the
Nuclear Safety Commission of Japan on March 27, 1989). If the facilities aredesigned and managed accordingly, there is no need for dose evaluation.

58

3. Individual systems of a reactor facility(11) Radiation control② Protection and management facilities[Basic requirements](Radiological protection for radiation workers)
1. The reactor facility shall be designed with radiological protection measures so as tosufficiently reduce radiation dose in areas accessed by radiation workers.
2. The reactor facility shall be designed with radiological protection measures so thatradiation workers can conduct necessary operations during an abnormal operationaltransient and a design basis accident.
(Radiation control for radiation workers)
3. The reactor facility shall be designed with radiation control facilities to protect
radiation workers from radiation.
4. The aforementioned radiation control facilities shall be designed to display
necessary information in the control room or other appropriate locations.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 57 & 58)[Requirement Details](Radiological protection for radiation workers)
A. “Design with radiological protection measures” in Paragraph 1 refers to the designthat incorporates relevant radiological protection measures such as shielding,equipment layout, remote control, prevention of radioactive material leakage, andventilation under the concept of ALARA and in consideration for the workability ofradiation workers.
(Radiation control for radiation workers)
B. “Radiation control facilities” refer to the facilities for radiation workers’ access
control, contamination management and decontamination, established formonitoring and managing radiation exposure.
C. “Displaying necessary information in the control room or other appropriate
59locations” refers to the ability to display the space dose rate, measured with area
radiation monitors for radiation control, in the control room, as well as the spacedose rate in controlled areas, in-air concentration of radiation materials and surface
concentration of contamination of radioactive materials on floors at otherappropriate locations.

60

3. Individual systems of a reactor facility(11) Radiation control③ Monitoring facilities[Basic requirements]
The reactor facility shall be designed to appropriately measure and monitor thedischarged radiation and radioactive materials during normal operation, abnormal
operational transient and design basis accident, and display necessary information in thecontrol room or other suitable locations.
(Corresponds to Regulatory Guide for Reviewing Safety Design of Light Water Nuclear
Power Reactor Facilities Guide 59)[Requirement Details]
A. “Appropriately gauging and monitoring” means the reactor facility can measure andmonitor the concentration of radioactive materials and space dose rate throughsampling and radiation monitors for the atmosphere inside the primary containment
vessel and in areas under surveillance surrounding the reactor facility and can also
gauge and monitor relevant locations such as radiation sources, discharge points,
around the nuclear power station, and at anticipated discharge channels ofradioactive materials, so as to facilitate quick response in the event of a design basis
accident.
B. The gas and liquid waste discharged into the environment during normal operation
should be measured and monitored according to the “Guidelines on themeasurement of radioactive materials discharged from light water nuclear reactor
facilities” (adopted by the Atomic Energy Commission on September 29, 1978).
C. The measurement and monitoring during a design basis accident should be
conducted according to the Review Guide for Radiation Measurement During
Accidents from Light Water Nuclear Power Reactor Facilities (adopted by the
Atomic Energy Commission on July 23, 1981).
D. Monitoring posts shall be designed, if not connected to an emergency electrical
power distribution system, to secure the functionality until the restoration of power
supplies through the use of uninterruptible power supplies, etc. Also, thetransmission system of monitoring posts shall be designed to have diversity.

61

(12) Miscellaneous① Basic requirements on auxiliary boilers[Basic requirements]
1. Auxiliary boilers shall have the capacity to supply required steam under anticipatedusage conditions.
2. Auxiliary boilers must be designed to not compromise the safety of the reactor
facility.
(※Electrical facilities that need to have new standards defined due to the incorporationof the Electricity Business Act)
[Requirement Details]
A. "Capacity to supply required steam" refers to the ability to supply enough steam forstructures, systems, and components with safety functions.
B. "Design to not compromise the safety of the reactor facility" refers to design thatwould not affect the safety of the reactor facility even when the auxiliary boiler
becomes damaged.

62

4. Safety evaluation(1) Safety evaluation[Basic requirements]
1. Analysis and assessment shall be carried out against abnormal operational transientsand design basis accidents in order to confirm that the basic policies of safety design
for a reactor facility meet the requirements defined in 1 – 3.
2. The aforementioned analysis and assessment concerning abnormal operationaltransient shall confirm the following requirements are met. [Judging criteria for the
Evaluation Guideline 4.1]
a. The minimum critical power ratio or minimum critical output ratio shall exceed theallowable limit.
b. Fuel cladding shall not be mechanically damaged.
c. Fuel enthalpy shall not exceed the allowable limit.
d. The pressure applied to the reactor coolant pressure boundary shall be no more than
1.1 times the maximum service pressure.
3. The aforementioned analysis and assessment concerning a design basis accident
shall confirm that the following requirements are met. [Judging criteria for theassessment guideline 4.2]
a. The reactor core can be sufficiently cooled down without resulting in significant
damage.
b. Fuel enthalpy shall not exceed the limit.
c. The pressure applied to the reactor coolant pressure boundary shall be no more than
1.2 times the maximum service pressure.
d. The pressure and temperature at the containment vessel boundary shall not exceed
the maximum service pressure and temperature.
e. The reactor facility shall not cause significant exposure risk to the general public in
the surrounding areas(Corresponds to Regulatory Guide for Reviewing Safety Assessment of Light Water
Nuclear Power Reactor Facilities)[Requirement Details]
A. "Analysis and assessment against abnormal operational transient and design basis

63

accident" shall be performed based on the “Review Guidelines on the safety
evaluation of light water nuclear reactor facilities” and the “Meteorological
Guidelines on the safety analysis of light water nuclear reactor facilities” (adopted
by the Nuclear Safety Commission of Japan on January 28, 1982).

64