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The_engine_ear
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- TL;DR Summary
- If SCRAM completely removed all moderator from the reactor, would decay heat still be an issue?
Summary: If SCRAM completely removed all moderator from the reactor, would decay heat still be an issue?
My understanding of how decay heat occurs after shutdown in large scale Nuclear Power Reactors. Is that Beta Decay causes residual Neutron activity at a small fraction of the operating power level. This however is potentially still enough to damage plant and equipment in the event of a loss of cooling incident.
First thing first, is my understanding of the process correct?
If so, in the absence of a moderator, are these neutrons in the fast or thermal spectrum?
If it's the former, why not use a separate cooling loop on a PHWR?
Then just install a burst disk on the bottom of the pressurized reactor vessel. This way any over temperature event corresponds to a rise in pressure within the reactor vessel. The burst disk can be relied upon to fail open, at which time 100% of the heavy water moderator would instantly flash to steam, venting into a storage tank. To my way of thinking this would offer a fail-safe shutdown mode similar to LFTR designs, but should however operate much faster than a freeze plug.
Am I correct in my reasoning that complete removal of the heavy water moderator, eliminates decay heat after scram?
My understanding of how decay heat occurs after shutdown in large scale Nuclear Power Reactors. Is that Beta Decay causes residual Neutron activity at a small fraction of the operating power level. This however is potentially still enough to damage plant and equipment in the event of a loss of cooling incident.
First thing first, is my understanding of the process correct?
If so, in the absence of a moderator, are these neutrons in the fast or thermal spectrum?
If it's the former, why not use a separate cooling loop on a PHWR?
Then just install a burst disk on the bottom of the pressurized reactor vessel. This way any over temperature event corresponds to a rise in pressure within the reactor vessel. The burst disk can be relied upon to fail open, at which time 100% of the heavy water moderator would instantly flash to steam, venting into a storage tank. To my way of thinking this would offer a fail-safe shutdown mode similar to LFTR designs, but should however operate much faster than a freeze plug.
Am I correct in my reasoning that complete removal of the heavy water moderator, eliminates decay heat after scram?