Running Neural Network experiments in loop I need to run neural network training with different hyper parameters settings like this: 

for seed in range(2):
        NN_inst = FeedForwardNN(seed)
        NN_inst.load_data()
        NN_inst.classification_model()
        NN_inst.run_model()


First run everything works. On the second run I get tensorflow.python.framework.errors_impl.FailedPreconditionError: Attempting to use uninitialized value training/Adam/Variable_39
     [[{{node training/Adam/Variable_39/read}} = IdentityT=DT_FLOAT, _class=["loc:@training/Adam/Variable_39"], _device="/job:localhost/replica:0/task:0/device:CPU:0"]]

It looks like I need to clear tensorflow memory, but 

K.clear_session()
tf.reset_default_graph()


do not help. I am using Keras, error is on fit(). 
What should I do?
I using InteractiveSession() and closing it every time worked

sess = tf.InteractiveSession()
#code here ...
sess.close()