ML23048A271
| ML23048A271 | |
| Person / Time | |
|---|---|
| Site: | 99902106 |
| Issue date: | 02/17/2023 |
| From: | Adrian Muniz NRC/NRR/DANU/UAL2 |
| To: | Radiant |
| References | |
| Download: ML23048A271 (7) | |
Text
Manufacturing License Phasing and NUREG 1.232 Criteria 17 and 26 Questions Feb 17th, 2023
Manufacturing License Phasing
- What is an applicant not permitted to do without manufacturing license approval?
- Fuel a reactor?
- Purchase or build safety related SSCs?
- Purchase or build non-safety related SSCs?
- Buy tooling or test equipment?
- Build manufacturing facility?
- Purchase land for manufacturing facility?
- Additional phasing opportunities
- Gradual submission of SAR chapters
mHTGR Electrical Power Systems Electric power systems shall be provided when required to permit functioning of structures, systems, and components.
The safety function for each power system shall be to provide sufficient capacity and capability to ensure that 1.That the specified acceptable system radionuclide release design limits and the reactor helium pressure boundary design limits are not exceeded as a result of anticipated operational occurrences and 2.Safety functions that rely on electric power are maintained in the event of postulated accidents.
The electric power systems shall include an onsite power system and an additional power system. The onsite electric power system shall have sufficient independence, redundancy, and testability to perform its safety functions, assuming a single failure. An additional power system shall have sufficient independence and testability to perform its safety function.
If electric power is not needed for anticipated operational occurrences or postulated accidents, the design shall demonstrate that power for important to safety functions is provided.
Q) If all electrical safety functions can be carried out independent of the state of upstream electrical power, are the upstream electrical power systems non-safety?
Q) Can you specify the applicability of mHTGR-13 and mHTGR-64 relative to continued monitoring during an accident in which loss of electrical power is observed and the reactor is in a known safe state?
mHTGR Monitoring Radioactivity Release Means shall be provided for monitoring the reactor building atmosphere, effluent discharge paths, and plant environs for radioactivity that may be released from normal operations, including anticipated operational occurrences, and from postulated accidents.
mHTGR Instrumentation and Control Instrumentation shall be provided to monitor variables and systems over their anticipated ranges for normal operation, for anticipated operational occurrences, and for accident conditions, as appropriate, to ensure adequate safety, including those variables and systems that can affect the fission process and the integrity of the reactor core, reactor helium pressure boundary, and functional containment. Appropriate controls shall be provided to maintain these variables and systems within prescribed operating ranges.
The term independent and diverse indicates no shared systems or components and a design which is different enough such that no common failure modes exist between the system or means Principal Design Criteria - NUREG 1.232 - Criteria 26 Design Criterion 26 Reactivity control systems.
A minimum of two reactivity control systems or means shall provide:
(1) A means of inserting negative reactivity at a sufficient rate and amount to assure, with appropriate margin for malfunctions, that the specified acceptable system radionuclide release design limits and the reactor helium pressure boundary design limits are not exceeded and safe shutdown is achieved and maintained during normal operation, including anticipated operational occurrences.
(2) A means which is independent and diverse from the other(s), shall be capable of controlling the rate of reactivity changes resulting from planned, normal power changes to assure that the specified acceptable system radionuclide release design limits and the reactor helium pressure boundary design limits are not exceeded.
(3) A means of inserting negative reactivity at a sufficient rate and amount to assure, with appropriate margin for malfunctions, that the capability to cool the core is maintained and a means of shutting down the reactor and maintaining, at a minimum, a safe shutdown condition following a postulated accident.
(4) A means for holding the reactor shutdown under conditions which allow for interventions such as fuel loading, inspection and repair shall be provided.
Independent and Diverse Means of Reactivity Control
- NUREG 1.232 item 26 states that a minimum of two reactivity control systems or means shall satisfy 4 separate criteria.
- Question:
- Can a high temperature gas reactor design that utilizes peripheral control drums for reactivity control and shutdown satisfy the requirements of item 26 by utilizing 3 independent groups of drums?
- Assumptions:
- The instrumentation and actuation of each individual drum is independent.
- The energy source and means of control for each group of drums is independent.
- All drums are located at the periphery of the core and the drum design for each group is identical (height, diameter, poison material, supports).
- All other performance and safety requirements can be satisfied with defense in depth.
- There is no other reserve shutdown system.
- A hardware qualification program will demonstrate component and system functions.
Public Comment