Safety and Licensing HTR Module Siemens Design of the 80ies IAEA Course on HTR Technology Beijing, 22-26.October 2012 Dr. Gerd Brinkmann AREVA NP GMBH Henry-Dunant-Strasse 50 91058 Erlangen phone +49 9131 900 96840 fax +49 9131 900 94166 mail: [email protected]
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Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 2
HTR-Module - Power Plant for Cogeneration of Electrical Power and Process Heat
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 3
Nuclear Licensing Ordinance
Paragraph 3 - kind and extent of the documents
The application for a license is to be accompanied by the documents which are required
for the examination of the licensing prerequisites in particular
1. Safety analysis report, which ... in the safety analysis report shall be represented and
explained the concept, the safety related design bases, and the function of the plant
including its operation and safety systems. There are to be described the effects related
to the plant and its operation including the effects of accidents ...;
2. Supplemental plans, drawings and descriptions of the plant and its parts;
3. Information about measures provided to the protection of the plant and its operation
against disturbance or other interference by third persons ...;
4. Information allowing to check reliability and expert knowledge of the persons responsible
for the construction of the plant and the management and control of its operation;
5. Information allowing to check ...:
6. A list of all information important to the safety of the plant and its operation .... (safety
specifications);
7. Recommendations for provisions for compliance with legal liabilities for damages;
8. A list of the measures provided for the non-contamination of water, air and soil
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 4
Hierarchy of the German Rules and Regulations
Atomic
Energy
Act
Ordinances
(e.g. Nucl. Lic. O.,
Rad. Prot. O.)
Authoritative Regulations
(e.g. BMI-Safety Criteria, RSK Guidelines)
Technical Rules (e.g. KTA-Safety Standards,
DIN Standards)
Company International Regulations
and Specifications
BMI: Federal Minister of the Interior
RSK: Reactor Safety Commission
KTA: Nuclear Safety Standards Committee
DIN: German Inst. for Standardization
Co
ncre
tisation
and
De
taila
tio
n
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 5
Article 7a the Atomic Energy Act (AtG)
Upon application, a preliminary ruling may be
rendered with respect to individual aspects which
determine the granting of the license for an installation
under Article 7, ....
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 6
German Regulations for Design and Operation of Nuclear Power Plants
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 7
Contents of Report I Introduction
II Table of contents
III List of tables
IV List of figures
V Abbreviations
VI Codes from identification system for power plants (KKS)
VII Graphical symbols used for mechanical, electrical and instrumentation and control equipment
1 Site
2 General design features of the HTR module power plant
3 Power plant
4 Radioactive materials and radiological protection
5 Power plant operation
6 Accident analysis
7 Quality assurance
8 Decommissioning
9 Waste management provisions
10 Guidelines and technical rules
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 8
Schematic Representation of Participants in the Licensing Procedure under the Atomic Energy Act
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 9
Time Schedule of the Licensing Procedure / Safety Concept Review (I)
Apr 87 Application for initiation of concept licensing procedure
pursuant to Art. 7 a of the Atomic Energy Act docketed with
Lower Saxony Ministry for the Environment (licensing authority)
on the basis of safety analysis submitted by Siemens/Interatom
May 87 Lower Saxony Ministry for the Environment retains TÜV Hanover
to conduct safety review of HTR Module concept
Sep-Dec 87 Technical consultations with experts and licensing authority;
appr. 100 technical documents generated for this purpose
Feb 88 Experts call for more supplementary technical documents
Sep 88 Revision of safety analysis report completed; submission to
licensing authority and expert
Dec 88 Start of RSK consultations
Feb 89 Report on fire protection concept completed
Mar 89 Report on plant security concept completed
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 10
Time Schedule of the Licensing Procedure / Safety Concept Review (II)
April 89 Application for concept licensing procedure withdrawn by applicant
and proceedings suspended by Lower Saxony Ministry for the
Environment
May 89 Review continued by TÜV Hanover on behalf of BMFT
July 89 Draft review report submitted by TÜV Hanover
Sep 89 Final meeting of RSK Subcommittee for HTRs
Oct 89 Final meeting of RSK Subcommittee for Electrical Engineering
Dec 89 Completion of final review report
Mar 90 Recommendation on the HTR Safety Concept by RSK
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 11
Contents of Chapter 2 (SAR HTR Module)
> General design features of the HTR module power plant
> Introductory remarks
> Characteristic safety features
Barriers against release of radioactivity
Inherent safety
> Technical design features
Reactor
Nuclear steam supply system
Confinement envelope
Residual heat removal
Helium purification system
Fuel handling and storage
Emergency power supply
Reactor protection system
Remote shutdown station
Controlled area
> Nuclear classification and quality requirements
> Summary of design basis events
> Postulates and measures for in-plant events
> Postulates and measures for external events
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 12
Section 2.2 (SAR): Characteristic Safety Features
> The engineering configuration and nuclear design of the HTR module
is such that even in the event of postulated failure of all active
shutdown and residual heat removal systems, the fuel temperature
stabilizes at 1620°C. No appreciable release of radioactivity from the
fuel elements occurs below this temperature.
> Active residual heat removal systems which limit the loading on
components and structures surrounding the core can fail for several
hours without the allowable limits being exceeded.
> Assessment in report: approved
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 13
Section 2.3 (SAR): Technical design Features
> Fuel Element Coatings (TRISO)
Enrichment (8 ± 0,5%)
1620 °C max. temperature, minimal release through SiC layer
Particle failure curve (manufacturing defects: </= 6 x 10-5,
irradiation induced: </= 2 x 10-4; accident-induced: </= 5 x 10-4
Assessment in report: approved
> Reactor Core By virtue of core design, fuel temperature stays below 1620°C under all
accident conditions even on loss of active residual heat removal
Due to uranium content of 7 g per fuel element the reactivity excursion on
water leakage is less than on inadvertent withdrawel of all reflector rods
Design for unrestricted load cycling between 50 and 100%
Assessment in report: approved; restriction on part-load operation below
50% and during the running-in phase (because no analyses submitted for
this case): limits on absorber ball level in storage vessels
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 14
Section 2.3 (SAR): Technical Design Features (II)
> Shutdown Systems Shutdown by absorbers in reflector
Shutdown by 6 rods and 18 absorber ball units
Location of rod drive mechanisms in RPV
Location of all absorber ball unit components needed for shutdown in RPV
Assessment in report: design and configuration approved. Reactivity balances for
equilibrium core approved but those for running-in phase up to several months have
relatively small margins; consequences: reactor power might be below of 200 MW at
first
> Pressure vessel unit Consists of reactor pressure vessel, gas duct pressure vessel and steam generator
pressure vessel inclusive of valve banks on RPV, nozzles of steam generator pressure
vessel
Offset configuration, thus limiting natural circulation in the primary system
Leak before break, assured safety for entire pressure vessel unit
Assessment in report: approved after discussion of dissimilar-metal weld and change
of material for main steam nozzle. Requirement: preservice pressure test to include
RPV nozzles
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 15
Section 2.3 (SAR): Technical Design Features (III)
> Primary and secondary system isolation Primary system by two valves in each line of which only one operated by reactor protection system (failsafe) Secondary system by two valves in each line (failsafe) both actuated by reactor protection system whenever reactor is shut down. Consequently, rest of secondary system outside reactor building has no functions important to safety Primary system overpressurization protection: two safety valves; secondary system: one safety valve backed up by steam generator relief system Assessment in report: approved
> Confinement Envelope Consisting of reactor building and other features (secured subatmospheric pressure system, building pressure relief system, HVAC system isolation) Normal operation: no filtering At overhauls: filtering by exhaust air filtering system (aerosols) During major depressurization accident (non-isolable DN65 line): unfiltered venting through two dampers to vent sack Other depressurization accidents: possibility of filtering by subatmospheric pressure system (iodine filter) Environmental impact of all accidents far below limits prescribed in Art. 28.3 of the radiological protection ordinance even without active measures taken or filtering: consequently no containment necessary Assessment in report: approved. Requirement: higher grade exhaust air filtering system
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 16
Section 2.3 (SAR): Technical Design Features (IV)
> Residual heat removal Provided by secondary system, cavity coolers, helium purification system
On loss of active cooling, residual heat removed from core to cavity coolers solely by
thermal conduction, radiation and natural convection
Secured component cooling system, two-train
With cavity coolers intact and loss of core cooling, core can run hot for lengthy period
of time (15 h) without design limits for RPV and concrete of reactor cavity being
violated
External supply can be connected to cavity coolers in the event of severe accident
conditions
Assessment in report: approved (see emergency power supply below for restriction)
> Emergency power supply Two trains served by two diesel generator sets, started by operational sequencing
controls or by hand
DC busses (e.g. reactor protection system) battery-buffered for two hours
Reactor system can sustain loss of power for at least fifteen hours (loss of auxiliary
power supply, failure of diesel generator sets) without design limits being violated.
Assessment in report: approved. Restriction: quality assurance for diesel must be so
strict that the diesel generators can certainly be started within the fifteen-hour period
Dr. Brinkmann, IAEA Course on HTR Technology,Beijing,22-26.October 2012 Page 17
Section 2.3 (SAR): Technical Design Features (V)
> Reactor protection system Few process variables
Three protective actions always actuated on shutdown (reflector rod drop, blower trip,