ML20138R488
| ML20138R488 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 12/17/1985 |
| From: | Andrews R OMAHA PUBLIC POWER DISTRICT |
| To: | Martin R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| LIC-85-496, TAC-60913, NUDOCS 8512310312 | |
| Download: ML20138R488 (2) | |
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Omaha Public Power District 1623 H<irney Om<iha. Nebraska 68'02 2247 402 536 4000 i
l December 17,14Rk fj r n }
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LIC-85-496
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Mr. Robert D. Martin Regional Adninistrator U. S. Nuclear Requlatory Conmission Region IV 611 Ryan Plaza Drive, Suite 10D0 i
Arlington, TX 76011 i
References:
(1) Docket No. 50-2RS (2) Letter from 0 PPD (W. C. Joney) to NRC (J. T. Collins) dated June 14, 1984, LIC-84-196 (3) Letters from NRC (J. T. Colli.ns) to OPPD (W. C. Jones) dated June 22, 1994
Dear Mr. Martin:
Fort Calhoun Station Boric Acid Seccndary Addition Ef fects on Primary-to-Secondary '_eak Detection Capabilities Onaha Public Power Distric'2'(0 PPD) provided to the N7C a submittal (Reference ?.) outlining our intantion to install "in-line" injection of boric acid to the seconotry side of Fort Calhoun Station, Unit 1.
It is our intent to supplement that submittal.
Maintaining i concentration of boric acid in the seconiary system should reduce:
1) denting in the steam generators; and 2) intergranular stress corrosion cracking (IGSCC).
OPPD plans to perfom a boric acid soak during low power startup (approxinately 30% power) following our 1985 refueling outage.
The low power soak will be followed by on-line horic acid injection during the ensuing cycle.
Secondary system boric acid concentration will be main-tained at approximately 53 ppa during the 30% power soak and 5 to 10 ppm through the balance of the cycle by varying the injection rate with the steam generator blowdown rate.
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Mr. Robert D. Martin December 17, 1985 LIC-85-496 Page Two OPPD uses measurament of boric acid to determine primary-to-secondary leak rate during the hot shutdown mode of startup (and during the following mode 1 operation until radionuclides become measurable).
In all other modes of operation and shutdown, leak rate is measured with radionuclides. Our lower limit of leak detection with boric acid has been 0.03 gpm.
Improved analytical technique will drop the lower limit of leak detection to 0.012 gpm despite injection of boric acid. Detemination of leak rate by radionuclides is not affected.
Although OPPD's ability to detect (1ower) primary-to-secondary leaks is improved, the District realizes that indications of leak rate could be due to " hideout return" (i.e., boric acid entrenched in cracks or crevices during the soaking returning to solution). This masking effect would be short-lived, however, because the amount " hiding" will be relatively small. At any rate, given leak rate indications, OPPD would assume that the indications were leaks and would respond accord-ingly.
OPPD believes that the benefits derived from injection of boric l
acid to the secondary side and the increased sensitivity of the analyti-cal technique to detemine leaks by boric acid in the hot shutdown mode l
of startup far outweigh the possible masking by hideout.
If you should have any questions, please do not hesitate to call.
Sincerely,
.)psad' R. L. Andrews L
Division Manager Nuclear Production RLA/AND/lp i
cc:
LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Avenue, N.W.
i Washington, D. C.
20036 Mr. E. G. Tourigny NRC Project Manager i
Mr. P. H. Harrell NRC Senior Resi_ dent Inspector
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