MELGYM is a Gymnasium-based tool designed to facilitate interactive control over MELCOR 1.8.6 simulations.

Every control functionality in MELCOR is determined by Control Functions (CFs). However, the batch execution mode of MELCOR makes it difficult to interactively control and modify functions under certain user-defined conditions. Control conditions are defined a priori and sometimes requires the concatenation of several CFs that must be done in an unfriendly way.

MELGYM allows the definition of external user-defined controllers, allowing the use of reinforcement learning agents or any other custom/external control algorithm.

MELGYM leverages MELCOR's restart capabilities to modify CFs every few simulation cycles. Just before a warm start is performed, the underlying MELCOR model is modified according to the last registered simulation state, and continues running until the next control action is performed.

Check the MELGYM documentation for more detailed information.

MELGYM environments adhere to the Gymnasium interface, and can be combined with DRL libraries such as Stable-Baselines3.

import melgym
import gymnasium as gym
from stable_baselines3 import TD3

env = gym.make('branch_1', render_mode='pressures')

# Training
agent = TD3('MlpPolicy', env)
agent.learn(total_timesteps=10_000)

# Evaluation
obs, info = env.reset()
done = trunc = False

while not (done or trunc):
    env.render()
    act, _ = agent.predict(obs)
    obs, rew, trunc, done, info = env.step(act)      

env.close()

For faster experimentation, the run_experiment.py script allows to launch experiments by using the configuration defined in config.yaml.

$ ./run_experiment.py -conf config.yaml

See our contributing guidelines.

MELGYM rely on the auxiliar toolbox MELKIT. Feel free to help us improving both projects!