Forgive me for being so bold as to post my naive comments at this point.
I have never seen a Dogbone in person and have certainly not ever designed or built one.
Given that, I still have formed some opinions and observations after lurking on the fora all of these

It seems to me that we are designing a device that is somewhat like a Nuclear Power Plant, something
like a Coal-Fired Power Plant and something like a Propane Gas Grill.

Let us first look at Fission Power Plants and how they are controlled.

To control a nuclear power plant, we need to have a means of slowing down the reaction.  Control
rods that absorb some of the neutrons are used in this case.  When nuclear chain reactions are present,
we are apt to operate either at a subcritical point or an supercritical point.  Either we don't get enough
of  our chain reaction or we get too much of it and have a melt down.  When we are operating
subcritical, we get a COP of 1.2 or so.  When we are operating supercritical, we get a COP of 10 for a
while and then burn out...meltdown.  So far, Parkhomov and me356 seem to be spending some time
operating subcritical and when they try to boost the COP they end up operating in the supercritical
region of the curve and then they are having meltdowns.  Here is one of the more successful trials:

Fission plants use Control Rods to moderate the reaction. These are made with neutron-absorbing
material such as cadmium, hafnium or boron, and are inserted or withdrawn from the core to control
the rate of reaction, or to halt it.  This is fine, but very slow.  Another means is needed that reacts more
quickly to the situation.  In fission power plants, most of the neutrons are released promptly, but some
are delayed.  These delaying mechanisms are crucial in enabling a chain reacting system to be
controllable and to be able to be held precisely at the critical level.  

What is our moderator?   What are we absorbing and retaining for a bit to slow the reaction down?  
Do some isotopes of Ni act as a moderator?  Perhaps Ni64, due to its half-life and beta emission
capabilities  (T½ = 12.7 hours)?

The "Coefficient of Reactivity" is the curve that describes how any reactor responds to an increase in
temperature.  A "Void Coefficient of Reactivity"is different and plots what is happening to that curve
when we start to get bubbles in the water coolant.  Chernobyl is an example of a reactor that had a
positive portion of their Void Coefficient of Reactivity.  When they hit that portion of their curve, it
melted down (or melted up, if you prefer).

Do we have a negative slope in our Coefficient of Reactivity Curve over the whole range of our
operating temperatures?  
Do we have a negative slope in our Void Coefficient of Reactivity Curve over the whole range of our
operating temperatures?

We should, but it appears that we have not yet met this requirement.

Next, let us look at Coal Fired Heating Plants

In a coal fired plant, we have a source of coal and a source of oxygen to control the rate of burning.  
We also have a source of cool water to keep the boiler within an acceptable range of temperatures.

How about Propane Fired Outdoor Grills?

In a Propane Outdoor Grill, we have a source of C3H8 and a source of air/oxygen.  We can control the
amount of C3H8, but we cannot starve it for air lest we build up unburned Propane.

Back to LENR reactors
We have heard that Dogbones can have a rapid rise in temperature.  Is this more analogous to a
buildup in Propane or is it more like hitting a supercritical nuclear reaction?

The hotter something gets, the more rapid its heat gets conducted away from it.  

Can we control a dogbone simply by running enough cold water over it or do we need moderators on
the atomic level?
If it is like a Propane grill, should we be controlling the amount of H2?  Should we be controlling the
amount of H+?