3 ms·

RE: Furthermore, they were in the 1960s, before the NRC existed and before we worried about ALARA. "Exposure of personnel to radiation has been held well below

RE: Furthermore, they were in the 1960s, before the NRC existed and before we worried about ALARA. "Exposure of personnel to radiation has been held well below permissible limits: the maximum exposure of any individual in any quarter has been <0.5 rem." This is within the ALARA standards. http://moltensalt.org/references/static/downloads/pdf/NAT_MSREexperience.pdf http://moltensalt.org/references/static/downloads/pdf/NAT_MS... RE: no real fluid-to-fluid heat exchanger. MSRE had salt-to-salt and salt-to-air heat exchangers made from hastelloy-N. https://www.flickr.com/photos/oakridgelab/31537153147/ https://www.flickr.com/photos/oakridgelab/31537153147/ RE: or power conversion cycle, which is where lots of maintenance troubles arise from. That's the part which is not highly radioactive. Fluid fuel reactors have simplest fuelling mechanism of any reactors. The fuelling of a fluid-fuel reactor is even simpler than fuel injectors of diesel engine. Where the need for "maintanence" arise in this simple machine?? Only moving parts are the pump impellers and the control rods. ORNL had some difficulty designing the bearing, seals etc. for the salt pump. But, even that is solved today with concentrating-solar salt pumps.

acidburnNSA 7y ago
> Exposure of personnel to radiation has been held well below permissible limits Ah, the good old days! 25-50% of the radioiodine from MSRE is completely unaccounted for. No one knows where it went. This is wholly unacceptable from a modern regulatory approach. It will have to be found. http://moltensalt.org/references/static/downloads/pdf/ORNL-4865.pdf http://moltensalt.org/references/static/downloads/pdf/ORNL-4... > MSRE had salt-to-salt and salt-to-air heat exchangers made from hastelloy-N Fair enough. It's generally in the salt-to-water heat exchanger where major maintenance concerns take place in a power reactor. Check out steam generator problems in PWRs and SFRs to see what I mean. You're right that the radiation will be low there if they use an intermediate salt. But the baseline maintenance problems come in at the steam generator in most plants. So MSRE avoided any problems there but any power MSR will have them like any other reactor. Good old BWRs get around this via direct cycle. > Where the need for "maintanence" arise in this simple machine?? Pumps. Heat Exchangers. Valves. Flanges. Welds. Vessels. Graphite. Reflectors. Fission product processing equipment. Instruments/sensors. Control mechanisms. There are very complex systems with lots of things working together in a very tough environment (high radiation, high temperature). Maintenance is a major challenge.
- achalhp 7y ago
  RE: Ah, the good old days! <0.5 rem per quarter (or 5 mSV) is in compliance with today's dose limit. ORNL was a competent American national lab with high standards even back in the 1960s. Another hollow argument from today's incompetent nuclear industry. "Exposure of personnel to radiation has been held well below permissible limits: the maximum exposure of any individual in any quarter has been <0.5 rem." http://moltensalt.org/references/static/downloads/pdf/NAT_MSREexperience.pdf http://moltensalt.org/references/static/downloads/pdf/NAT_MS... "The maximum annual dose allowed for radiation workers is 20 mSv/yr" https://www.world-nuclear.org/information-library/safety-and-security/radiation-and-health/nuclear-radiation-and-health-effects.aspx https://www.world-nuclear.org/information-library/safety-and...

acidburnNSA 7y ago

> Exposure of personnel to radiation has been held well below permissible limits Ah, the good old days! 25-50% of the radioiodine from MSRE is completely unaccounted for. No one knows where it went. This is wholly unacceptable from a modern regulatory approach. It will have to be found. http://moltensalt.org/references/static/downloads/pdf/ORNL-4865.pdf http://moltensalt.org/references/static/downloads/pdf/ORNL-4... > MSRE had salt-to-salt and salt-to-air heat exchangers made from hastelloy-N Fair enough. It's generally in the salt-to-water heat exchanger where major maintenance concerns take place in a power reactor. Check out steam generator problems in PWRs and SFRs to see what I mean. You're right that the radiation will be low there if they use an intermediate salt. But the baseline maintenance problems come in at the steam generator in most plants. So MSRE avoided any problems there but any power MSR will have them like any other reactor. Good old BWRs get around this via direct cycle. > Where the need for "maintanence" arise in this simple machine?? Pumps. Heat Exchangers. Valves. Flanges. Welds. Vessels. Graphite. Reflectors. Fission product processing equipment. Instruments/sensors. Control mechanisms. There are very complex systems with lots of things working together in a very tough environment (high radiation, high temperature). Maintenance is a major challenge.

achalhp 7y ago
RE: Ah, the good old days! <0.5 rem per quarter (or 5 mSV) is in compliance with today's dose limit. ORNL was a competent American national lab with high standards even back in the 1960s. Another hollow argument from today's incompetent nuclear industry. "Exposure of personnel to radiation has been held well below permissible limits: the maximum exposure of any individual in any quarter has been <0.5 rem." http://moltensalt.org/references/static/downloads/pdf/NAT_MSREexperience.pdf http://moltensalt.org/references/static/downloads/pdf/NAT_MS... "The maximum annual dose allowed for radiation workers is 20 mSv/yr" https://www.world-nuclear.org/information-library/safety-and-security/radiation-and-health/nuclear-radiation-and-health-effects.aspx https://www.world-nuclear.org/information-library/safety-and...