ML19345B700
| ML19345B700 | |
| Person / Time | |
|---|---|
| Issue date: | 09/12/1980 |
| From: | Sherry R NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Murley T NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| Shared Package | |
| ML19345B680 | List: |
| References | |
| FOIA-81-16, REF-10CFR9.7 NUDOCS 8012020365 | |
| Download: ML19345B700 (4) | |
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!10TE TO: Thomas E. !!urley, Director Division of Reactor Safety Research FROM:
R. R. Sherry Experimental Advanced Safety Technology 3 ranch
SUBJECT:
RESEARCH PROGRAMS RELATED TO 10DIliE RELEASE AtiD TRAtiSPORT UllDER ACCIDEtiT C0tlDITI0 tis" This note summarizes our current and planned research programs which provide information related to understanding iodine species behavior (in particular CsI) under accident conditions.
As you are aware, NRC regulatory assumptions related to iodine behavior (within containment) assume the existence of only three physicchemical forms of iodine - molecular (91 percent), organic (4 percent), and particulate (5 percent).
However, since about the time of the RSS, a number of investigators have become concerned that the principal form of iodine released under LWR accident conditions may not be I, but Csl.
2 The following paragraphs describe our current and planned research programs which address this question.
Fission Product Release From Defected LWR Fuel - ORNL This prcgram, which was completed last year, has provided most of the evidence which exists on the chemical forms of fission products released from fuel rods under LWR accident conditions.
Under this program, equilibrium thermodynamic calculations, separate effects tests, and heating tests with segments of commercially; irradiated fuel rod segments have provided evidence indicating that the principal iodine chemical species released from-defected fuel rods into a steam environment is CsI.
Secarate Effects Tests for TRAP Code Development - Sandia 1
The purpose of this program is to measure the vapor pressure of important fission product species at elevated temperature and to investigate the chemical reactions between fission products and (1) steam (and H ). (2) 2 prototypic RCS surfaces, and (3) other fission products under high temperature (Teax = 1000*C) conditions. Tests, so far, using Csl have indicated that CsI is stable at temperatures up to approximately 800*C in nitrogen / steam and nitrogen /H2 gas mixtures and does not readily react with stainless steel or nickel surfaces.
I have asked Sandia to investigate the high temperature
- stability of Csl in fi /02 and t19/H 0/02 2
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environments.
They plan to do this in the near future.
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Thomas E. Murley 12 E Fissien Product Transoort Analvsis - BCL The TRAP code is currently capable of modelling steam phase Csl transport within the primary system (although in the past iodine was assumed to be in elemental form for calculational exercises - e.g., sensitivity studies.
It can be expected that TRAP calculations will show that when iodine is in the form of Cs! the amount of iodine condensing on primary system surfaces and " washing out" within the RCS will be significantly-larger than if the assumed chemical form for iodine is I.
In addition, CsI 2
that does not condense on a system surface may nucleate (or condense on other particles) to form aerosols.
Hence, the iodine form in the con-tainment atmosphere under accident conditions may be primarily particu-late CsI (assumming the Cs! is not oxidized upon entry into containment) rather than elemental iodine.
Fission Product Release from Hich Temoerature Fuel - ort 1L_
In this research program we plan to investigate fission product release from LUR fuel rods into a steam environment under severe core damage and core melt temperature conditions (1000*-2800'C).
As part of this program, methods (e.g., laser Raman spectroscopy) of determining the chemical form (s) of fission products released from the rods will be investigated.
Fission Product Transoort Verification Facility - Undesicnated Plans are currently being developed to conduct integral experiments for validating the large fission product transpor t codes (e.g., TRAF-MELT, CORRAL,C0tiTAlfi,etc.).
In this program (to be conducted in the ORf1L/f1SPP and/or HEDL/CSTF facilities), it will be possible to determine the transport behavior of Csl under large-scale, near-prototypic conditions and to determine if our current computer models are adequate for describ-ing the transport behavior of CsI.
Icoine and Tellurium Behavior Under Accident Conditions - ORitL The purpose of this research (which is part of Don Hoatson's coolant chemistry program) is to investigate the chemical species of iodine and tellurium during vapor phase and liquid transport in RCS or containment aqueous solutions as a function of the local thermo-chemical conditions (chemistry, temperature, pressure,etc.).
This program will include a determination of the partitioning of these species between the liquid and vapor phases.
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Thomas E. Murley SEP 12Isc0 t
I Fission product Source Term Definition for Degraded Core Cooling Conditions -
ORNL f
.The Office of Standards Development has recently requested that RES initiate a short term (< 1 year) program to develop fission product source tt., for accidents more severe than a design basis LOCA to aid OSD in developing regulatory guides in the areas of biological shielding requirements for fluid systems which penetrate containment (e.g., ECC, l
t letdown) and for preparing interim recommendations for degraded core accident analysis source terms. The primary objective of this effort l
will be to review and evaluate the existing fission product release and transport data base and to generate source terms applicable.to a range of degraded core conditions, accident scenarios, and potential transport pathways. An important aspect of this program will be to provide real-istic source terms for the volatile fission products (noble gases, iodine,andcesium).
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j R. R. Sherry Experimental Advanced Safety l
Technology Branch Division of Reactor Safety Research l
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Suggested Agenda Commission Meeting on Fission Product Release During Accidents November 18, 1980 10:00 A.M.
I.
Iodine Release During Accidents 1.
Presentation by Drs. Stratton, Malinauskas and Campbell:
a)
Synopsis of technical bases for their Aug. 14, 1980 letter b)
Impact of the perceived excessive safety ma. gin for iodine releases 2.
Presentation by F. von Hipple 3.
Staff Response to Question 2:00 P.M.
II. Estimates of Consequences of Accidents 1.
Presentations by industry representatives:
C. Starr, Ml Levinson, I. Wall 2.
Comments by Dr. Schikarski 3.
Presentations by Dr. H. Kouts III. Comments by the Staff N
1.
Potential Impact on Regulatory Requirements (NRR) 2.
Impact on Core Melt Accident Consequence Spectrum (RES) 3.
NRC Research Programs Related to Iodine Release (RES)
.