ML20141A161
| ML20141A161 | |
| Person / Time | |
|---|---|
| Issue date: | 11/07/1985 |
| From: | Silberberg M NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Saffell B Battelle Memorial Institute, COLUMBUS LABORATORIES |
| Shared Package | |
| ML20140J438 | List: |
| References | |
| FOIA-85-772, RTR-NUREG-0956, RTR-NUREG-956 NUDOCS 8604040404 | |
| Download: ML20141A161 (3) | |
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Subj NOV 7 1985 Circ Chron Branch r/f JMitchell JMitchell r/f rberg RMe er Mr. Bernard F. Saffell, Jr. assett ,
Program Manager WMorrison i 505 King Avenue RMinogue i Columbus, OH 43201 Dross i D::ar Mr. Saffell: '
Subject:
Aerosol Groupings for In-Vessel and Containment Aerosol Codes In the past, the grouping of chemical elements for calculations of off-site consequences of severe reactor accidents has been based on the groups chosen t l
for the Reactor Safety Study (RSS, WASH-1400). With the advent of the source l term analytical procedure as used in BMI-2104, much more information is cvailable on chemical behavior, and chemical elements that were perceived to behave the same in the RSS are now perceived to behave differently. However, the calculations in BMI-2104 did not follow a large number of chemical element )
groups or chemical compounds and some of the additional insights based on the l chemical behavior were lost. Since some of these elements have radionuclides '
of biological important (for instance, Np and Pu), the number and grouping of elements followed in the source term calculations has been reviewed for continued adequacy. It has been concluded by consensus among a small group consisting of J. Mitchell, J. Martin, and J. Read of NRC and H. Ludwig of BNL that the grouping should be changed for the Source Term Code Package (STCP).
It is expected that future consequence calculations will use the MACCS code, which has no restriction on the number of element groups and would be able.to use the expanded information directly. If CRAC or CRAC2 is used, however, thi l groups may be recombined as necessary to provide the information for the RSS
. grouping.
The chemical elements, chemical element, groups and chemical compounds followed !
as aerosols in the analyses for some of the calculations reported in BMI-2104 and the set recommended for the STCP are given in Table 1. For those calculations in BMI-2104 that reported the full Reactor fety Study release fractions, the grouping of the masses of materials for either in-vessel release or ex-vessel release is given in the first section of Table 1. For those calculations that only reported I, Cs, and Te releases, the grouping of masses is given in the second.section of the table. In this latter case, the masses of materials that were previously followed separately were lumped into the aerosol mass.
The justification for the revised set of groups given in the third section of l Table 1 can be found in Draft NUREG-0956. Tables 4.8 and 4.9 show higher i fractional releases for Ba than Sr for in-vessel releases while Tables 4.10 and 4.11 show the reverse for ex-vessel releases. Therefore, their release fractions could show sequence specific behavior. La and Ce groups are not evaluated in the CORS0R in-vessel release model, but show different ex-vessel release fractions in Tables 4.10 and 4.11. The other la'nthanides and actinides previously in the La group were divided according to whether the 8604040404 860210 PDR FDIA SHOLLY85-772 PDR g
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Mr. Bernard F. Saffell, Jr. chemistry of La or of Ce was believed to be more appropriate as a surrogate. -
Separating in-vessel and ex-vessel lumped aerosols will allow hand calculations of oxidized species for sequences where direct heating of the containment atmosphere is assumed.
In all cases the noble gases Xe and Kr are followed in the MARCH calculation and also were reported for the Reactor Safety Study grouping releases. They should continue to be followed for STCP calculations and reported.
i In sumary, the revised grouping recommended for the STCP calculations should i provide the information that will allow off-site consequence calculations to /
take the best possible advantage of the develeping insights on chemical behavior. This letter confirms our telephone request to J. Gieseke in July 1985.
Sucerely, Original Signao ey M. Silberberg, Branch Chief Fuel Systems Research Branch Division of Accident Evaluation !
Office of Nuclear Regulatory Research
Enclosure:
Jable 1 _
cc: T. Margulies, NRC J. Martin, NRC l J. Read, NRC l H. Ludgwig, BNL !
R. Bari, BNL !
T. Pratt, BNL R. Denning, BCL P. Cybulskis, BCL j J. Gieseke, BCL i D. Powers, SNL l T. Kress, ORNL 1 DAE:FSRB DAE:FSRB DAE:FSRB l Mitchell:md Meyer Silberberg 11/6/85 11/ / /85 11/7/
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Table 1: Components followed as aerosols in BMI-2104 calculations and as recommended for STCP calculations.
- 1. "MI-2104-RSS groups I-Br*
Cs-Rb*
Te-Sb-Se Sr-Ba Ru-Rh-Pd-Tc-Mo La-Eu-Pr-Nd-Pm-Sm-Y-Nb-Zr(f.p.)-Ce-Np-Pu Aerosol
- 2. BMI-2104-Volatile releases only I-Br*
Cs-Rb*
Te-Sb-Se Aerosol
- 3. Source Term Code Package I-Br*
Cs-Rb*
Te-Sb-Se Ba - -
Sr Ru-Rh-Pd-Tc-Mo La-Eu-Pr-Nd-Pm-Sm-Y-Nb-Zr(f.p.)
Ce-Np-Pu In-vessel aerosol Ex-vessel aerosol I
- The transport of these elements is followed as if the masses had the vapor and chemical properties of Csl or Cs0H.
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