ML20133N346
| ML20133N346 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom, Surry, 05000000 |
| Issue date: | 02/20/1985 |
| From: | Cybulskis P Battelle Memorial Institute, COLUMBUS LABORATORIES |
| To: | Jeffrey Mitchell NRC |
| References | |
| RTR-NUREG-0956, RTR-NUREG-956 NUDOCS 8508130458 | |
| Download: ML20133N346 (3) | |
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!clem 24 i 454 February 20, 1985 Ms. Jocelyn Mitchell U.S. Nuclear Regulatory Commission Willste Building - P-822 7915 Eastern Avenue Silver Spring, Maryland 20910
Dear Jocelyn:
As discussed during last month's meeting in Columbus, we have reviewed the MARCH results for the Surry and Peach Bottom sequences in order to quantify the noble gas releases that would be expected in each of these cases.
As you are well aware, MARCH is not designed to address questions of fission product transport and deposition; however, for purposes of fission product decay heat distribution to be used in the thermal hydraulic analyses MARCH does incorporate an approximate tracking of the various fission product groups.
The MARCH model is quite appro-priate for the behavior of the noble gases.
The noble gas release re-suits obtained are discussed below.
Surry Sequences AB-BETA The BMI-2104 analyses included two variations on the treatment of the AB-BETA sequences.
The first, labeled 2-volume, considered the primary as well as the secondary containments, with each modeled as a single separate volume.
The second, labeled 4-volume, considered only the primary containment but subdivided it into four compartments.
The fractional noble gas leakages to the environment derived from the MARCH analyses for the two cases are 0.89 and 0.82, respectively.
These values are at the end of the calculations; it is reasonable to infer that essen-tially all the noble gases would be released eventually for these cases.
AB-GAMMA The results for the AB-GAPPM sequence indicate release of 0.83 of the noble gases at the end of the calculation; complete release would be expected eventually.
AB-EPSILON For this sequence, the fractional noble gas release at the end of the calculation was 0.15.
This value was relatively low because the analysis took into account the hydrostatic pressure outside the containment basemat; i
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February 20, 1985 I
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Ms. Jocelyn Mitchell USNRC l
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since the containment pressure at the time of predicted meltthroug I
is relatively low, only a fraction of the containment atmosphere isSinc f
I predicted to be released.quite low, further leakage to the environment would d
I S2D-GAMMA The fractional noble gas release for this sequence at the end of t l
sequence keeps the containment pressure low, except for the large hy-calculation is 0.46.
drogen burn that is postulated to lead to failure of cont the total release.
S20-EPSILON i
The MARCH calculation for this sequence was not carried out to the po n be of containment meltthrough, thus leakage to the environment must The operation of the containment sprays during tnis sequenceAt the inferred.
keeps the containment pressure low.
thus the containment pressure was calculated to be near atmospheric; little leakage to the environment would be indicated even at the t pressure take place relatively early in the sequence when the con of basemat penetration.
of 0.01 of the noble gases to the environment.
TMLB-BETA Complete release of the noble gases was calculated for this sequence; time this particular MARCH calculation was carried out for a longer than a number of the other sequences.
TMLB-0 ELTA i
The fractional noble gas release at the end of the t
lly.
TMLB-EPSILON The fractional release of the noble gases for this sequence at the end The large release in this case compared f
of the calculation was 0.82.
to the other basemat meltthrough cases is due to the to atmospheric pressure.
V SEQUENCE i
The fractional gas release for this sequence at the end of the calculat o was 0.95; complete release would be expected eventually.
f I
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N Ms. Jocelyn Mitchell 3
February 20, 1985 USfiRC Peach Bottom Sequences Complete release of the noble gases was indicated for all three of the Peach Bottom sequences analyzed in Biil-2104. The relatively small free volume of this containment together with higher noncondensable generation from concrete decomposition in comparison with the Surry results leads to little or no retention of the noble gases in any of these sequences.
I trust that the above will be of benefit in your preparation of fiUREG-0956.
Sincerely,
/,) /
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hi: U.in
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' -Peter Cybulskis [
fluclear Systems Section cc:
R. Meyer, flRC PC:dem
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