Whose measurements these are
Ingrid Švajger and Luka Snoj of the Jožef Stefan Institute published the reactor’s pulses, one record at a time.
Their pulse database, of the institute’s Reactor Physics Department, gives each pulse of cores 215, 217 and 231, of 2014, 2015 and 2018. The models on this page are the verifier’s validated models of those published data. The data are the institute’s. The credit for every measurement is theirs.
- The measurements
- Ingrid Švajger and Luka Snoj, Jožef Stefan Institute
- The database
- Pulse experiments on TRIGA Mark II at “Jožef Stefan” Institute. Reactor Physics Department, Ljubljana: trigapulse.ijs.si
- The constants
- I. Švajger, D. Čalič, A. Pungerčič, A. Trkov and L. Snoj, Evaluation of reactor pulse experiments. Nuclear Engineering and Technology 56(4), 1165–1203, 2024: doi.org/10.1016/j.net.2023.11.021. Open access under CC BY-NC-ND 4.0.
- The hot-rod factor
- Ingrid Vavtar, Analiza fizikalnih parametrov reaktorskega pulza, master’s thesis, University of Ljubljana, 2019: hdl.handle.net/20.500.12556/RUL-109204
- The reactor’s design
- Matjaž Ravnik, Description of TRIGA Reactor, course note, Jožef Stefan Institute, Reactor Infrastructure Centre
What happened
The power climbs to hundreds of megawatts, and the heating of the fuel turns it back.
The records give each pulse’s peak power, the energy released and the reading of the thermocouple in element 6753, for pulses of 1.4 to 3.0 printed dollars.
The institute’s physicists put the records of the reactor’s pulses online, each with its power and the reading of the thermocouple in one fuel element.
This page is about two models: one of the reactor through a pulse, and one of fuel element 6753, fed by the reactor’s release of energy. A run of the reactor hands its pulse to the element under one chain proof, the coupling triga_pulse_to_element_6753.
None of the database’s measured values is stored in either model. They are the record both are held to.
What the model did
On all 16 pulses not in the fit, fuel element 6753’s thermocouple maximum comes within 9.2 percent.
The reactor’s model computes power, energy released and core-average fuel temperature through the pulse, the scram and after it, by point kinetics with six delayed groups and fuel-temperature feedback, on the rod tables of cores 215, 217 and 231. It is fitted on 36 of the 43 recorded pulses: ten constants, a scale and an offset for each rod table, two feedback coefficients, the generation time and the heat flow to the water.
Compared with the 20 table rows of the same cores not in the fit, in units of the comparison’s uncertainty: on 12 rows of core 231 from March 2018, peak power within 1.21 RMS against a target of 1.5 (18.0 percent), energy within 50 ms of the peak within 1.47 and the thermocouple maximum within 1.29 (8.0 K); on 8 repeats of core 217 at 2.5 dollars, peak power within 1.09 (5.6 percent high).
The element’s model carries radial conduction through the zirconium rod, the uranium-zirconium-hydride meat, a gas gap and the steel clad, 1.387/56 of the core’s energy into the meat, convection and boiling to the pool, and the thermocouple as a first-order lag, every step’s energy account closed to 1e-9. It is fitted on 39 pulses with two constants: the gap conductance, 1780 W/m² K, and the thermocouple’s time constant, 1.03 seconds. On 16 pulses of cores 217 and 231 not in the fit, from each record’s own power, the thermocouple’s maximum rise is within 9.2 percent on all 16 (target 10), its time after the power peak within 19.6 (target 20), and the rise 10 seconds after the peak within 4.3 on the 8 records that run that long.
The largest gaps: the reactor’s peak power reads 44 and 23 percent low on the two rows of 22 March 2018, a day whose printed 1.5 and 2.0 dollars stand at rod positions the fitted day prints as 1.75 and 2.25; below 2.0 dollars peak power reads 29, 21 and 9 percent low at 1.4, 1.6 and 1.8 dollars. The element’s maximum rise reads 7.7 percent low at the mean on the 2015 core 217.
Asked for a pulse of 2.0 dollars on the rod table of core 217 from 25 °C, the reactor’s model gives a peak of 139.8 megawatts at 0.174 seconds with 2.50 megawatt-seconds released to the peak, the core-average fuel reaching 408.2 K by the end of the run. The run comes back with the proof d2da4051…3b39be, 96 characters of SHA-384, and the signature of the verifier’s answer key.
A dataset of 16 card runs and 141 solves of element 6753, sealed on engine 0.15.0, is on Hugging Face.
Comparedwith measurement
Element 6753, all 16 pulses within9.2%
Its target10%
Where it stops
Compared at 2.0 to 3.0 printed dollars. Past that it computes with the same equations. It refuses more than the rod’s whole worth.
In the verifier’s own words: “Past what a model was compared with, it keeps going with the same equations and flags every step. It stops only at a physical limit, or where its equations, constants or tables no longer hold, and it names the reason.”
What it was compared on
- The reactor: 2.0 to 3.0 printed dollars, starts of 20.9 to 29.2 °C, scrams 1.51 to 7.45 seconds after the peak, up to 954 MW and 585 K.
- The element: starts of 293.14 to 305.53 K, core energy releases of 6.85 to 19.41 MW s, core power to 994 MW, histories in 1 ms and 10 ms intervals to 14 seconds.
Past that, and what its own description says of itself
- The reactor: any reactivity above zero up to the rod’s whole worth of 4.16 printed dollars, any start in liquid water and any scram time or none.
- The element: any start of liquid pool water from 273.15 to 385 K and any history up to 600 seconds, with the same equations; each answer outside the compared span carries one of four
*_outside_comparedkeys. - The reactor refuses a reactivity above the rod’s whole worth (
ReactivityAboveRodWorth), a rod table other than those of cores 215, 217 and 231 (RodTableOutsideCard) and a start outside liquid water (StartTemperatureNotLiquidWater). - The element refuses the meat above 1150 °C (
FuelAboveSafetyLimit) and a clad heat flux above Zuber’s critical heat flux, 1.47 MW/m² (CriticalHeatFluxPassed).
For the reader who wants every number
The reactor, in the verifier’s own words.
Everything above is this page’s telling. What follows is the verifier’s own, exact and whole: the spec sheet of the model energy/reactor_triga_jsi as version 0.15.0 serves it in its description, in its six parts, with its word for how it stands against measurement: compared with measurement. The verifier’s current description is the one to trust. Where it says card it means a model, and where it says refuses it names the reason a run stops.
What it computes
Pulses of the TRIGA Mark II reactor of the Jozef Stefan Institute, Ljubljana (56-element core of standard U-ZrH fuel, rod tables of cores 215, 217 and 231), by point kinetics with six delayed groups and fuel-temperature feedback: power, energy released and core-average fuel temperature through the pulse, the scram and after it.
Range
Range: compared at 2.0 to 3.0 printed dollars, starts of 20.9 to 29.2 degC, scrams 1.51 to 7.45 s after the peak, up to 954 MW and 585 K; computes any reactivity above zero up to the rod’s whole worth of 4.16 printed dollars, any start in liquid water and any scram time or none.
Fitted on
Fitted on 36 of the 43 recorded pulses of cores 215, 217 and 231 in the institute’s pulse database, 1.4 to 3.0 printed dollars: ten constants, a scale and an offset for each rod table, two feedback coefficients, the generation time and the heat flow to the water, with five more fitted to the instruments.
Compared with
Compared with the 20 table rows of the same cores not in the fit, other days on the fitted tables, in units of the comparison’s uncertainty: on 12 rows of core 231 from 22 and 28 March 2018, peak power within 1.21 RMS (target 1.5; 18.0 percent), energy within 50 ms of the peak within 1.47 (15.7 percent) and thermocouple maximum within 1.29 (8.0 K); on 8 repeats of core 217 at 2.5 dollars, peak power within 1.09 (5.6 percent high), thermocouple maximum within 0.42 (2.1 K low) and energy within 2.01 (5.4 percent high).
Gap
Gap: peak power reads 44 and 23 percent low on the two rows of 22 March 2018, a day whose printed 1.5 and 2.0 dollars stand at rod positions the fitted day prints as 1.75 and 2.25 (worst 3.02, target 3); on the 2018 rows the worst energy and thermocouple maximum reach 3.75 and 3.10 (target 3); below 2.0 dollars peak power reads 29, 21 and 9 percent low at 1.4, 1.6 and 1.8 dollars; the fuel temperature is compared through one thermocouple of one element.
Refuses
Refuses a start outside liquid water, 273.15 to 373.124 K (StartTemperatureNotLiquidWater), a reactivity of zero or less (ReactivityNotPositive) or above the rod’s whole worth of 4.16 printed dollars (ReactivityAboveRodWorth), a rod table other than those of cores 215, 217 and 231 (RodTableOutsideCard) and a reactivity changed during a run (ReactivityChangedDuringRun).
Fuel element 6753, in the verifier’s own words.
Everything above is this page’s telling. What follows is the verifier’s own, exact and whole: the spec sheet of the model solver fuel_rod_triga_jsi as version 0.15.0 serves it in its description, in its six parts, with its word for how it stands against measurement: compared with measurement. The verifier’s current description is the one to trust. Where it says card it means a model, and where it says refuses it names the reason a run stops.
What it computes
Temperature of the instrumented fuel element 6753 of the JSI TRIGA Mark II reactor through a pulse, from the core’s energy release given as a history: radial conduction through the zirconium rod, the U-ZrH1.6 meat, a gas gap and the SS-304 clad by backward Euler in the enthalpy, 1.387/56 of the core’s energy into the meat, convection and boiling to the pool, and the fuel thermocouple as a first-order lag, every step’s energy account closed to 1e-9.
Range
Range: compared from starts of 293.14 to 305.53 K and core energy releases of 6.85 to 19.41 MW s, core power to 994 MW, histories in 1 ms and 10 ms intervals to 14 s; computes any start of liquid pool water from 273.15 to 385 K and any history up to 600 s with the same equations, each answer outside the compared span carrying one of four *_outside_compared keys.
Fitted on
Fitted on 39 pulses of cores 215, 217 and 231, 1.4 to 3.0 printed dollars: two constants, the gap conductance, 1780 W/m2 K, and the thermocouple’s time constant, 1.03 s; refitted on all 55 pulses the same pair is the best, on a grid of 7.5 percent steps about it.
Compared with
Compared with 16 pulses of cores 217 and 231 at 2.0 to 2.6 printed dollars not in the fit, from each record’s own power: the thermocouple’s maximum rise within 9.2 percent on all 16 (9.2 low to 0.3 high, mean 5.5; target 10), its time after the power peak within 19.6 percent (mean 11.9; target 20), and the rise 10 s after the peak within 4.3 percent on the 8 records that run that long (mean 3.1; target 10).
Gap
Gap: on all 55 pulses the maximum rise reads 6.3 percent low on the 2014 core 215 and 7.7 on the 2015 core 217 at the mean, 2.2 on the 2018 core 231; a gap conductance per core leaves core 217 at 7.4 percent low and moves only the time of the maximum, while 8 to 10 percent more of the core’s energy in the element closes it; fed by the reactor_triga_jsi card through the coupling, the 10 s rise reads 11.2 to 5.0 percent low.
Refuses
Refuses a start outside a liquid pool (StartTemperatureOutsideLiquidPool), times not rising (HistoryTimesNotRising), energy released falling (EnergyFalls), the meat above 1150 degC (FuelAboveSafetyLimit), a clad heat flux above Zuber’s critical heat flux, 1.47 MW/m2 (CriticalHeatFluxPassed), and a history past 600 s, the capacity of one solve (HistoryBeyondCapacity).
Hand this one to your agent.
https://mcp.zerotrustphysics.com/mcp
Something to paste
Connect to https://
Give it this page too.
What it will find
The two spec sheets: what each computes, its range, what it was fitted on, what it was compared with and how close it came, its gap and what it refuses.