ML20023D304
| ML20023D304 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 05/17/1983 |
| From: | Lentine F COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 6585N, NUDOCS 8305200351 | |
| Download: ML20023D304 (4) | |
Text
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(( ]h Commonwealth Edison
) One First Nitional Plaza, Chicago, Illinois
\\ v 7 Address Heply to: Post Office Box 767
~
(,/ Chicago, Illinois 60690 May 17, 1983 Mr. James G. Keppler, Regional Administrator Directorate of Inspection and Enforcement - Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137
Subject:
Zion Station Units 1 and 2 Response to I.E.
Inspection Report Nos. 50-295/82-30 and 50-304/82-27 NRC Docket Nos.-50-295 and 50-304 References (a):
February 16, 1983, letter from D.L.
Farrar to J. G. Keppler.
(b):
January 17, 1983, letter from J.A.
Hind to Cordell Reed.
Dear Mr. Keppler:
Reference (a) provided Commonwealth Edison's response to the subject Inspection Report for Zion Station.
In that response, Commonwealth Edison committed to investigate the source and significance of Bromine-82 in containments and report the findings to the NRC Region III.
The Attachment to this letter provides the report on the results of our investigation.
To the best of my knowledge and belief the statements contained herein and in the attachment are true and correct.
In some respects these statements are not based on my perscnal knowledge but upon information furnished by other Commorwealth Edison employees.
Such information has been reviewed in accordance with Company practice and I believe it to be reliable.
Please address any questions you may have regarding this matter to this office.
Very truly yours, fb F. G. Lentine Nuclear Licensing Administrator 1m Attachment MAY 181983 8305200351 830517 6585N PDR ADOCK 05000295 G
PDR ff.' ()l
ATTACirdENT
~
Zion Station Units 1 and 2 Response to I.E.
Inspection Report Nos.
50-295/82-30 and 50-304/82-27 4
Subject:
Bromine-82 investigation at Zion Nuclear Power Station st
References:
10 JANE 3 Memo to R. F. Coley ent itled "Results of the Nuclear Regulatory Commission Confirmatory Measurement Program and Audit."
26JANS3 Memo to B.
J.
Schramer entit led "Analyt ical Services ' Response to the Zion Stat ion Requests Concerning the Results of the Nuclear Regulatory Commission Confirmatory Measurement Program Audit. "
INTRODUC TION The Nuclear Regulatory Commission (NRC), during confirmatory measurements between 08DEC62 and 13DEC82, cited Zion stat ion with various findings as stated in the 10JANB3 memo referenced above.
One of these findings was that Zion failed to ide nt ify Br-62 in the ir charcoal cartridge containment samples.
The Analyt ical Services Group, as per Zion stat ion 's request (26JAN63 memo), proceeded with an invest igat ion of the source of Br-62.
This nuclide may be produced in two generic ways:
by the neutron act ivat ion of Br-81, or by the fission of uranium fuel.
The following reflects the results of our investigation.
BR-82 FISSION FRAGMENTS One would expect that bromine isotopes and iod ine isotopes would be chemically comparable af ter adequate considerations are made for the physical differences of these two elements.
L od ine -131 is a fission product with a fission yield of more than 10,000 times greater than that of Br-82 according to Meek and Rider
("Compilat ion of Fission Product Yields" General Electric document NEDO-12154-1, 74NED6, 26JAN74).
Offsetting this is the fact that the diatomic radius of GrZis 1.2 t imes that of Br (2.7 angstroms /2.3 angstroms).
The migrat ion of bromine from the fuel and through the cladding would thus be greater than that of iodine.
The conditions of elevated temperatures and pressures in the primary 10.0p increases the probability that bromine will be found less in the coolant and more in the atmosphere that iod ine.
Subject:
Bromine-82 Invest igat ion at Zion Nuclear Power Stat ion NEUTRON ACTIVATION OF BR-81 The concentrations of Br-82 were calculated arouna reactor trips from unit containment iodine charcoal cartridge samples collected and analyzed over the period from JAN82 to DEC82.
These concentrations were then compared to the concentrations of Na-24, which is only an activation product, taken from containment part iculate samples analyzed over the same period.
An examination of the data shows that the concentrations of both Br-82 and Na-24 are close in magnitude to each other.
The following calculation indicates that Na-24 should be approximately 130 times as abundant as Br-82 if their mechanisms of production are the same.
Br-81 and Na-23 are contained in Lake ' Michigan water in the following amounts:
[Br-81] = 18 ppb
- 49.3% natural abundance = 8.9E-03 ppm
[Na-23] = 6.0 ppm
- 100% natural abundance = 6.0 ppm The above concentrat ion information was obtained from Argonne National Laboratory and the System Materials Analysis Department of Commonwealth Edison Company.
One may assume that the average neutron flux is the same for any sample quantity of water in which both sodium and bromine l
are contained.
The following relationship results:
R R
=
N
- sigma N
- sigma (Na)
(Br)
The variables R, N and sigma are, respect ive ly, the thermal-neutron (n, gamma) react ion rate, the concentration of the reactant nuclide, and the thermal-neutron cross sect ion.
Rearrang ing and subst itut ing, the following ratio results:
R (Na) 6.0 ppm
- O.53 barns
=
130
=
R 8.9E-03 ppm
- 2.7 barns (Br)
9
Subject:
Bromine-82 investigation at Zion Nuclear Power Station _
lt should be noted that other sources of Br-81 were invest igated.
=
They included the charcoal cartridge it se l f, electrical cables in containment, paint and insulat ion.
I believe such sources to be insignificant in comparison to the Br-81 found in the feedwater.
Other salient facts are that bromine is much more likely to concentrate in containment air samples than sodium, given bromine 's greater volatility, and that LLDs appropriate to both Br-82 and Na-2k are roughly similar in reactor coolant samples.
Na-24 is readily seen in part iculate samples b'ut Br-82 is not.
CONCLUSIONS Based upon the above informat ion, the Analytical Services Group believes that the most probable source of Br-82 is the neutron-act ivat ion of Br-81 found originally in Lake Michigan water.
It is our understanding that Br-82 has been observed in other nuclear stations as well as at Zion station for over a year.
The observed concentration of this nuclide, regardless of its source, poses no threat to the operation of the plant or to the environment.
Respectfully submitted, l
9 fY).
h,
.ub Joseph M. Di Santi Radiochemistry Team f
i Approved:
Lb 0 0 l
G.
D. Cole Team Leader Radiochemistry JMD/kjb cc:
G. P. Wagner K.
L. Graesser R. F. Coley l
G.
J.
Plimi l
A.
J.
Kennedy T. A. R ieck M.
E. Di Ponzio B. E. Harl
__