ML20210S542

Submits Addl Info Re Radiochemistry Program for Primary to Secondary Leakage Detection & Quantification,Per 860812 Telcon Request

ML20210S542
Person / Time
Site:	McGuire, Mcguire
Issue date:	09/22/1986
From:	Tucker H DUKE POWER CO.
To:	Harold Denton, Youngblood B Office of Nuclear Reactor Regulation
References
TAC-61775, TAC-61776, NUDOCS 8610080169
Download: ML20210S542 (2)

Text

. s DUKE POWER GOMPANY P.O. DOX M3180 CIIAHLO1TE, N.C. 28242 IIAL 13. TUCKEH TELEPHONE vu a ememenent (704) 373-4531 w~trie r=a==vvvo=

September 22, 1986 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555 ATTENTION: Mr. B.J. Youngblood, Director PWR Directorate No. 4

Subject:

McGuire Nuclear Station Docket No. 50-369, 50-370

Dear Mr. Denton:

Discussions between our respective staffs in support of the F* criterion for steam generator tube plugging (reference McGuire license amendments 59 and 40 for Units 1 and 2, respectively) involved inquiries into our radiochemistry program at McGuire Nuclear Station for primary to secondary leakage detection and quanti-fication. It was agreed in a telephone conference on August 12, 1986 between D.

Hood, D. Sellers, and T. Sullivan of your staff and R. Gill, J. Day, and R. Michael of my staff that the radiochemistry information provided in that call would be supplied in a follow-up letter, but would not be required prior to issuance of the amendment; the subject information is provided herein.

The normal surveillance frequency is once weekly. If a significant change in the leak rate is observed, the surveillance is increased appropriately until the leak l

rate has stabilized, at which time weekly sampling is resumed. It has been l generally observed that leak rate changes in steps.

The normal calculation is based upon the ratio of Xenon-133 gn the off gas and in the primary coolant. Based upon 12 scfm offgas with 1 x 10- microcuries/ml Xe-133 and 0.1 microcuries/mi Xe-133 in the primary systca, the leak rate is calculated to be 1.3 gallons per day. If the quantity of offgas is less than 12 i

scfm (typical is 8-12 scfm), the detection limit is proportionately lower. A leak rate of 5-10 gpd is sufficient to pinpoint the affected steam generator. If for some reason the Xenon calculation does not appear valid, a calculation based upon iodine may be employed.

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8610080169 860922 PDR P ADOCK 05000369 I i PDR D

Mr. Harold R. Denton, Director September 22, 1986 Page 2 Steam line monitors which alarm'in the control room and the condenser evacuation system noble _ gas monitor which also alarms in the control room are available to detect any sudden change in leak rate between normal samplings if the leak is of a sufficient magnitude to be of concern.

It is in Duke's interest not only from a safety, but an economic standpoint as 1 well to operate with minimum leakage due to possible secondary side (turbine) contamination, important issue.thus we consider the possibility of primary to secondary leakage an Very truly yours,

/

- l/ g Hal B. Tucker JBD/83/jgm xc: Darl Hood (NRC/0NRR)

E.J. Sullivan (NRC/0NRR)

W.T. Orders (NRC/MS)

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