How about your own neighborhood nuclear energy plant?

[RD]

Because in the case of an accident resulting in an uncontrolled reaction, the only way to cool the core is with vast amounts of water.

Light water reactor?

Remove the water, and the reaction naturally collapses.

Joe

True, but without an ultimate heat sink, the pressure increases.

[MaineShark]

Because in the case of an accident resulting in an uncontrolled reaction, the only way to cool the core is with vast amounts of water.

Light water reactor?

Remove the water, and the reaction naturally collapses.

True, but the pressure increases.  PV = nRT

Pressure in what?  What fluid is being pressurized?  We just removed the water.  If there's anything left, it's some steam and such.  It can't moderate the reaction, the core will start cooling on its own.

Or course, the light water moderates automatically; as the temp increases, the density of the water decreases, and so does its ability to slow neutrons.  So the reaction slows.  Which cools the water.  Which increases the density, and thereby increases the reaction.  The process repeats as a closed-loop feedback cycle.

Joe

[RD]

But there is decay heat, caused by the radioactive fission products, which continues to increase temperature and pressure if no cooling water is available.

[MaineShark]

But there is decay heat, caused by the radioactive fission products, which continues to increase temperature and pressure if no cooling water is available.

Pressure of what?

There is also radiative and conductive heat loss, even without cooling water.

Joe

[RD]

But there is decay heat, caused by the radioactive fission products, which continues to increase temperature and pressure if no cooling water is available.

Pressure of what?

There is also radiative and conductive heat loss, even without cooling water.

Joe

Pressure inside the containment vessel.  You can't just cool the containment vessel via heat radiation and conduction to the outside air.  The pressure (and temperature) inside would build so much faster, due to decay heat, than you could exchange that heat if there is no cooling water present - i.e. an ultimate heat sink.

[MaineShark]

Pressure inside the containment vessel.

Not pressure where, pressure of what?  What fluid is being pressurized?

You can't just cool the containment vessel via heat radiation and conduction to the outside air.  The pressure (and temperature) inside would build so much faster, due to decay heat, than you could exchange that heat if there is no cooling water present - i.e. an ultimate heat sink.

Really?  How many btu's per hour of decay heat do you imagine will be produced by a reactor that small?

Joe

[RD]

Pressure inside the containment vessel.

Not pressure where, pressure of what?  What fluid is being pressurized?

Well if there is no water, then the fluid would be the air in the containment vessel.

You can't just cool the containment vessel via heat radiation and conduction to the outside air.  The pressure (and temperature) inside would build so much faster, due to decay heat, than you could exchange that heat if there is no cooling water present - i.e. an ultimate heat sink.

Really?  How many btu's per hour of decay heat do you imagine will be produced by a reactor that small?

Joe

I have no idea.  It would depend on the amount of fuel and the percent power the reactor was running at when it shut down.  But if it would power a neighborhood, I wouldn't want to be anywhere near it if there is no sufficient supply of cooling water available.  Think about it; there is a specific reason why naval vessels can be powered by nuclear reactors, but non-seagoing vehicles cannot.

[MaineShark]

Well if there is no water, then the fluid would be the air in the containment vessel.

And...?  Know anything about the physical characteristics of air?  What sort of pressure increase will it actually have, relative to temperature increase?

Really?  How many btu's per hour of decay heat do you imagine will be produced by a reactor that small?

I have no idea.  It would depend on the amount of fuel and the percent power the reactor was running at when it shut down.  But if it would power a neighborhood, I wouldn't want to be anywhere near it if there is no sufficient supply of cooling water available.  Think about it; there is a specific reason why naval vessels can be powered by nuclear reactors, but non-seagoing vehicles cannot.

Yeah, there is a specific reason: government regulation.

Joe

[RD]

And...?  Know anything about the physical characteristics of air?  What sort of pressure increase will it actually have, relative to temperature increase?

Pressure is proportional to temperature given a constant volume.  The problem is, eventually, the pressure will be great enough to breech the containment vessel, releasing highly radioactive iodines, noble gases, and other fission products.

Really?  How many btu's per hour of decay heat do you imagine will be produced by a reactor that small?

I have no idea.  It would depend on the amount of fuel and the percent power the reactor was running at when it shut down.  But if it would power a neighborhood, I wouldn't want to be anywhere near it if there is no sufficient supply of cooling water available.  Think about it; there is a specific reason why naval vessels can be powered by nuclear reactors, but non-seagoing vehicles cannot.

Yeah, there is a specific reason: government regulation.

Joe

I think in this case it's actually a physical regulation.

[MaineShark]

And...?  Know anything about the physical characteristics of air?  What sort of pressure increase will it actually have, relative to temperature increase?

Pressure is proportional to temperature given a constant volume.  The problem is, eventually, the pressure will be great enough to breech the containment vessel, releasing highly radioactive iodines, noble gases, and other fission products.

What sort of actual pressure increase will the actual gas actually attain?

You're the one asserting a danger, here.  Demonstrate it.  If I put my hand on a sealed bottle of soda, there will be a pressure increase due to my body heat; doesn't mean there will be any danger of an explosion.  You're suggesting that the pressure increase due to the heat in this system is going to cause a catastrophic failure of the pressure vessel, so why don't you find a high school physics textbook and calculate it...

I think in this case it's actually a physical regulation.

Really?  And what does that mean?

Joe

[RD]

I'm not trying to argue with you, I'm just commenting on the physical requirements of a safe nuclear reactor, because I happen to know something about the subject.  I don't need to do the calculations; they've been done for me many times over for many many years by many many nuclear engineers.

[MaineShark]

I'm not trying to argue with you, I'm just commenting on the physical requirements of a safe nuclear reactor, because I happen to know something about the subject.

Apparently not all that much.

It is not difficult to design a reactor that simply cannot "meltdown" or ever develop enough pressure to breach its pressure vessel,  short of loading it with excessively-rich fuel.

I don't need to do the calculations; they've been done for me many times over for many many years by nuclear engineers.

So you should easily be able to post the results, then, eh?

Joe

[RD]

I don't need to do the calculations; they've been done for me many times over for many many years by nuclear engineers.

So you should easily be able to post the results, then, eh?

Although I did my graduate work in nuclear structure, a good friend that I went to school with, Ed Seabury, has published several papers on decay heat measurements.  I hope to catch up with him at a conference in Oakland at the end of the month, and will ask him about it.  In the meantime, here is some of his work:

Fission-Product Studies
G.P. Couchell, W.A. Schier, D.J. Pullen, E.H. Seabury, J.M. Campbell, S. Li, H.V. Nguyen,
and S.V. Tipnis (University of Massachusetts - Lowell)

This report summarizes aggregate decay-heat measurements and individual fission-product
nuclide cumulative and independent yield measurements that have been both completed and analyzed.
The research covered three separate areas of fission product studies:
- aggregate gamma-energy distributions and decay heat of 235,238U and 239Pu;
- aggregate beta energy distributions and decay heat of 235,238U and 239Pu;
- cumulative and independent yields of short-lived fission-product nuclides of 235,238U.

The primary reason for these studies was to provide tests for evaluated nuclear data files
associated with fission, particularly extending down to very short delay times where no reliable
measurements existed.

Aggregate gamma-ray energy spectra have been measured for fission products resulting from
the thermal-neutron fission of 235U and 239Pu, and from the fast-neutron fission of 238U. The
measurements were performed using a beta-gated 5"x5" NaI (TI) spectrometer and covered an
energy range of 0.1-8.0 MeV. Spectra were taken over a decay time range of 0.1 - 40,000s, with
measurements made at approximately three decay times per decade. An average gamma-ray energy
was determined for each spectrum and the gamma-ray decay heat as a function of decay time was
deduced from the average gamma-ray energy, measured gamma-to-beta activity ratio and the
measured beta activity as a function of time. Since the noble gases transferred by the helium jet are
not retained by the tape transport system, these results represent the gamma decay heat excluding
noble gases. CINDER[1] calculations were used to estimate the noble-gas contribution at each decay
time. Correction factors were thus generated to account for the loss of noble gases. Corrected
gamma-ray decay heats for 235,238U and 239Pu were compared with CINDER calculations and with
earlier ORNL [2,3] and YAYOI [4-6] measurements. The agreement is generally good except at the
shortest and longest decay times. At the shortest decay times there are no earlier measurements for
comparison, but our decay heat values are somewhat higher than the CINDER calculations. At the
shorter decay times the ENDF/B-VI fission-product data base used in the CINDER calculations is
supplemented by theoretical estimates based on the Gross Theory [7,8] of beta decay and a
gamma-ray cascade model [9] for estimating the gamma-ray spectra for many unmeasured fission
products. Our measurements suggest that the discrepancy lies mainly with the aggregate
gamma-to-beta activity ratio, rather than with the average gamma-ray energy or the relative beta
activity.

Beta energy spectra have been measured for the aggregate fission products resulting from
thermal neutron fission of 235U and 239Pu, and from fast neutron fission of 238U. The beta spectrometer
consisted of a 3"x3" plastic scintillator, gated by an optically isolated thin-disk scintillator mounted
on its surface for gamma-ray suppression. Measured spectra covered a beta energy range of 0.15-8.00
MeV and spanned a decay time range of 0.4 - 40,000s in steps of approximately three decay times
per decade. The average beta energy was calculated for each energy distribution, after correcting for
the 150-keV cutoff of our spectrometer. The beta decay heat was obtained by forming the product
of the average beta energy times the relative beta activity. Again the result was corrected for loss of
noble gases. Results of the present study were compared with the earlier ORNL measurements [2,3]
in the case of 235U and 239Pu and with the YAYOI beta decay heat results [4-6] for 238U. The present
results have been normalized to give the best overall agreement with the CINDER10 calculations. For
235U and 239Pu our results are in excellent agreement with those of ORNL throughout their region of
overlap. Excellent agreement was also observed between our 238U beta decay and that reported in
the YAYOI study. For 235U and 239Pu both our measurements and the ORNL results are in excellent
agreement with the CINDER10 calculation everywhere, except in the vicinity of 1000s decay time
where both measurements suggest a slightly higher value for the beta decay heat. The UML and
YAYOI beta decay heat measurements for 238U are also in excellent agreement with CINDER10
calculations, with only a similar slight discrepancy in the vicinity of 1000s.

These studies have also determined independent and cumulative fission-product yields
following fission of 235,238U. Measurements of high-resolution gamma-ray spectra, following the
thermal-neutron fission of 235U have been made with a Compton-suppressed, beta-gated, high-purity
germanium detector at the UML Van de Graaff facility. The gamma spectra were measured at delay
times ranging from 0.2s to nearly 10,000s following rapid transfer of the fission fragments with a
helium-jet system. On the basis of known gamma transitions, forty isotopes have been identified and
studied. By measuring the relative intensities and lifetimes of these transitions and using their
published beta-branching ratios, the relative probabilities for direct production of the various
precursor nuclides have been calculated. Metastable and ground state yields have been measured in
several cases. The division between metastable and ground-state yields tends to be quite uncertain
in the ENDF/B-VI compilation and therefore the current measurements are an important contribution
to this file. Elemental yields for rubidium, cesium, strontium and barium fission products have been
compared to those in ENDF. Even-odd effects in the distributions of partial elemental yields were also
clearly observed.

Measurements of gamma-ray spectra following fast-neutron fission of 238U with the HPGe
system described above were performed in a fast-neutron port on the UML Research Reactor. The
cadmium-shielded fission chamber resided near the core and the counting system was located at a
nearby shielded area. The gamma spectra were measured over delay times ranging from 0.3s to
4,000s. A total of 63 independent yields and 63 cumulative yields have been determined from our
measurements and compared to ENDF/B-VI. Our experimental values typically have uncertainties
of 10% or less while the ENDF values have typical uncertainties of 25% or more. Only 28% of the
nuclides in this study have previously measured independent and cumulative yield values
listed in ENDF with the remainder based solely on model calculations. The overall agreement with
ENDF/B-VI is reasonable, with 57% of the values falling within one standard deviation (68%
expected) and 81% falling within two standard deviations (95% expected).

As expected, a near-Gaussian distribution of elemental yields in our measurements was
observed for rubidium, strontium, yttrium, cesium, barium, and lanthanum. In most cases the
distributions are quite similar to those of ENDF, although our measured distribution for yttrium
indicates a shift to lower mass numbers.
__________
[1] T.R. England, W.B. Wilson, and M.G. Stamatelatos, Fission Product Data for Thermal Reactors,
Part 2: Users Manual for EPRI-CINDER Code and Data, Report LA-6745-MS, Los Alamos
National Laboratory, 1976; also published as Report EPRNI NP- 356, Part 2, Electric Power
Research Institute, December 1976.
[2] J.K. Dickens, T.A. Love, J.W. McConnell, and R.W. Peele, "Fission-Product Energy Release
for Times Following Thermal-neutron Fission of 239,241Pu Between 2 and 14000s", Nuclear Science
and Engineering 78, 126, 1981.
[3] J.K Dickens, T.A. Love, J.W. McConnell, and R.W. Peele, "Fission-Product Energy Release for
Times Following Thermal-neutron Fission of 235U Between 2 and 14000s", Nuclear Science and
Engineering 74, 106, 1980.
[4] M. Akiyama, K. Furuta, T. Ida, K. Sakata, and S. An, Journal of the Atomic Energy Society of
Japan 24, 709, 1982.
[5] M. Akiyama and S. An, "Measurement of Fission-product Decay Heat for Fast Reactors",
Proceedings of an International Conference on Nuclear Data for Science and Technology, Antwerp,
Belgium, 237, 1982.
[6] M. Akiyama and J. Katakura, Measured Data of Delayed Gamma-ray Spectra from Fissions of
232Th, 233,235U, and 239Pu by Fast Neutrons - Tabular Data, Report JAERI-M-88-252, Japan Atomic
Energy Research Institute, 1988.
[7] J. Katakura and T. England, Augmentation of ENDF/B Fission-product Gamma-ray Spectra by
Calculated Spectra, Report LA-12125-MS, Los Alamos National Laboratory, 1991.
[8] K. Takahashi and M. Yamada, Progress in Theoretical Physics 41, 1470, 1969; S. Koyama, K.
Takahashi, and M. Yamada, Progress in Theoretical Physics 44, 633, 1970; K. Takahashi, Progress
in Theoretical Physics 45, 1466, 1971.
[9] T. Yoshida and J. Katakura, Nuclear Science and Engineering 93, 193, 1986.

[MaineShark]

I don't need to do the calculations; they've been done for me many times over for many many years by nuclear engineers.

So you should easily be able to post the results, then, eh?

Although I did my graduate work in nuclear structure, a good friend that I went to school with, Ed Seabury, has published several papers on decay heat measurements.  I hope to catch up with him at a conference in Oakland at the end of the month, and will ask him about it.

Please do keep us informed.  I'd be very interested to hear about information that contradicts everything currently known about nuclear energy.

Joe

[kola]

wow huh