ML19345B696
| ML19345B696 | |
| Person / Time | |
|---|---|
| Issue date: | 10/30/1980 |
| From: | Pasedag W Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19345B680 | List: |
| References | |
| FOIA-81-16, REF-10CFR9.7 NUDOCS 8012020359 | |
| Download: ML19345B696 (4) | |
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I UNITED STATES j
NUCLEAR REGULATORY COMMISSION
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WASHlWGTort. D. C. 20555
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\\.v....o OCT 3 01980 I
MEMORAtlDUM FOR: Distribution FROM:
Walter F. Pasedag, Leacer, Raciological dnalysis hection Accident Evaluation Brancn, OSI
SUBJECT:
MIIlUTES OF MEETIt!G WITH URS. STRATT0ft, MALIslAUSKAS, A!!U CAMPBELL In response to a letter to Chairman Ahearne dated August 14, 1980, by Drs. W. R. Stratton, A. P. Malinauskas and D. O. Campbell, the flRC staff invited the authors to discuss the content.and bases of their letter.
A meeting was held for this purpose at 9:00 A.M., October 22, 1950 in room P-il8 at the Phillips Building.
The first presentation was given by Dr. A. P. Malinauskas.
Dr. Malinauskas' main topic was the chemical form of iodine in the fuel rod and during it's release from the fuel during an accident.
Dr. Malinauskas reviewed several thermodynamic and post-irradiation fission product release studies.
His emphasis, however, was on the Gap Purge Experiments by Lorenz, Osborne, Collins, and Malinauskas. These experiments involved fully irradiated fuel elements from the H. B. Robinson and Peach Bottom plants.
In these~experi-ments, iodine released from the fuel gap during heating (up to a maximum of about 16000 C) was deposited along with Cesium in a thermal gradiint tube at temperatures between 200 and 9000 C, indicating that the iac.1e form could not have been elemental iodine vapor, but, most likely, was cesium iodide.
Malinauskas also mentioned observations of concurrent release of small quantities of cesium and iodine into the primary cooling system during normal operation (" lodine spiking phenomenon").
In his review of previous experiments, Malinauskas acknowledged that the release of 1 trom LWR fuel was observed, but noted that sucn releases occurred when the carrier gas included air (intentionally or unintentionally).
2 Another possibility for compromising results can arise from the use of quartz in high temperature test apparatus, which can lead to the formation of cesium silicates and I. This reaction, as well as possible air ingress 2
were postulated to have invalidated the results of Castleman et al (1965-1967),
who observed elemental iodine releases in steam atmospheres.
Similar problems were postulated for experiments conducted in the United Kingdom and Japan.
Malinauskas concluded that iodine resides in the fuel as an iodide, which most likely is CsI, not in the volatile elemental form.
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Minutes of Meeting of October 22, 1930 OCT 3 01980 2-Or. Campbell tollowed with a presentation of lodine chemistry in an aqueous environment.
He reviewed the chemical species identified in the literature, and discussed the significant volatile species, i.e. molecular valance, 2), organic iodides, and other species with some state of positive iodine (I termed hypoiodous acid (HUI) by some investigators,.although the i
.existance of the latter form has never been conclusively proven.
He quoted the authoritative work of A. Eggleton, who calculated iodine volatility based on data available in the literature (1967), which he presented in the form of " partition coefficients."
Campbell then discussed the iodird chemistry following the TMI-2 accident.
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He noted that he believed the vatue quoted for the iodine concentration lon 4/1/80) in the Kemeny report to be in error by an order of magnitude.
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The partitio'n coefficient expected at TMI if the iodine were released as 2 was 5 x 10, which would put cbout.0.1% of the iodine released into the 4
1 gas phase. Actual measurements, however, were stated to be lower by about a factor of 10, i.e. 0.007% according to the sample taken on J/31/79.
Samp 4
l water samples, however, contained a substantial amount of copper (of uniden-as well as iron, nickel, aluminum, and calcium. The copper tified origen),
and iron of the sump water samples was largely reduced cuprous and ferrous
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oxides, indicating that any iodine in the sump water would nave to exist as iodide. Thus, Campbell concluded that the water in the TMI reactor building was strongly reducing, and, therefore, essentially no oxidation of iodide.
occurred.
l Campbell concluded with a discussion of organic iodides and radiation effects on iodine chemistry. He stated that, although predominant in the pre-purge atmosphere at TMI-2, organic iodides, as a total, constitute a very small fraction of the iodine introduced into.the containment. Concerning radiation effects, he noted C. C. Lin's finding that the OH radical oxidizes lodide, which react further to form iodate at low concentrations, but concluded that is not a significant reaction product under realistic accident conditions.
I2 He concluded that organic iodide formation will be lower than that predicted by.Postma and Zavadoski (WASH-1233), since little I2 is postulated to per-severe in the containment atmosphere.
Or. Stratton concluded 'the presentation with a discussion of past experience with accidents involving a substantial release of fission products,. ranging from the flRX accident in 1952 to.the TMI-2 accident in 1979.. He divided f
accidents into two categories, i.e. those with a reducing environment, and those with an oxidizing environment.
In addition to the flRX reactor accident, Stratton listed SilAP, SPIRT, SL1, ETR, and PRTR as examples of accidents with reducing environments, and noted that no lodine was released in these accidents, with the exception of a minor
.i release (0.5%) for the SL1 accident.
In contrast to these accidents, Stratton noted substantial iodine releases in the Windscale and flRU reactor accidents, and the Heater 3 experiments in 1958.
Stratton stated that the group strongly recommends that the itRC establish a task force to examine fission product behavior.
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j Miautes of Maeting of'Uctober 22, 1950 OCTJ 0 isa0
_3, Questions by the staff were invited during and following these presentations.
In response to staff. questions, Malinauskas emphasized that the stated con-clusions were not applicable to those accidents in which the fission products are released into an at. osphere containing air. Stratton stated that their remarks v.ere intended to address those accidents where containment integrity i
is maintained. - Stratton also clarified that the phrase " current URC models" contained in the August 14 letter referred to Regulatory Guides 1.3 and 1.4.
i The staff pointed out that NRC's cdrrent regulatory models are not restricted l
to Reg. Guides 1.3 and 1.4, and that the iodine partition coefficient models of Eggleton are used by the staff to evaluate the behavior of iodine in aqueous environments.
Other staff comments emphasized the regulatory philosophy, that the design basis accident analyses, as reflected in Reg. Guides 1.3 and 1.4, and TID-14844, ;
was not intended to be a realistic treatment of accidents, but an intention-ally conservative treatment of a hypothetical " design basis" event. The three i
authors of the August 14 letter agreed that the Reg. Guide 1.3 and 1.4 assump-i tions were indeed conservative, but.noted that this conservatism distorts the i
actual risk to the public as perceived by them.
The meeting concluded with an expression of the staff's appreciation of the willingness of Ors. Stratton, Malinauskas, and Campbell to elaborate on and discuss with the NRC staff the content and basis of their August 14 letter to Chaiman Ahearne.
//
C Walter t. Pasedag i
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