ML20215J722

Submits Addl Info Re Mods to post-accident Sampling Sys in Effort to Improve Sys Reliability & Provide Alternate Analyses for Boron,Chlorides & Reactor Bldg Atmosphere Radioisotopes.Criterion 10 of NUREG-0737 Satisfied

ML20215J722
Person / Time
Site:	Rancho Seco
Issue date:	05/04/1987
From:	Julie Ward SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Miraglia F NRC
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.B.3, TASK-TM JEW-87-750, TAC-60632, NUDOCS 8705080216
Download: ML20215J722 (3)

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SACRAMENTO MUNICIPAL UTILITY DISTRICT E P. O. Box 15830, Sacramento CA 95852-1830.(916) 452-3211 AN ELECTRIC SYSTEM SERVING THE HEART OF CALIFORNIA MAY 0 41987 JEW 87-750 Director of Nuclear Reactor Regulation Attention: Frank J. Miraglia, Jr.

Division of PWR Licensing-B U S Nuclear Regulatory Commission Washington D C 20555 Docket 50-312 Rancho Seco Nuclear Generating Station Unit #1 POST ACCIDENT SAMPLING SYSTEM (PASS) - ADDITIONAL INFORMATION ON ACCURACY AND RANGE

Dear Mr. Miraglia:

In letters dated February 6, and March 13, 1986, the District deceribed modifications being made to the Post Accident Sampling System (PASS) at Rancho Seco. These modifications are the result of a continuing effort to improve system reliability and to provide for alternate analyses (interim grab sample on-site analysis) for boron, chlorides and reactor building atmosphere radioisotopes.

The District's April 30, 1986 letter advised that additional modifications were being made to the PASS to further improve the system reliability, maintainability, analytical accuracy, and ALARA. These changes were part of the long term program presented at the February 18, 1986 meeting held at Region V and were implemented because of the extended outage. The intent of the long term program is to restore all of the in-line analysis capability .

originally intended for PASS. However, the interim grab on-site boron and reactor building radioisotope analyses and the off-site chloride analysis described in the District's February 6, and March 13, 1986 letters will be retained until the District is satisfied with the reliability of the in-line boron, chloride, and reactor building radioisotope analysis capabilities of PASS.

The ranges and accuracies (i.e. error) given in the District's June 17, 1983 letter were for individual instruments within the PASS that were provided by the equipment manufacturer. Subsequent operational experience in conjunction with the installed equipment euggests that this vendor supplied information was based on optimum conditions and does not reflect the overall system accuracy under existing conditions. The modifications that have been made to PASS as described in the District's April 30, 1986 letter have extended the lower limits of detection to include normal operational levels. The three analyses most affected are: 1) Boron, 2) chloride, and 3) Total gas. Ranges 8705080216 870504 PDR ADOCK 05000312 A P PDR Q

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DISTRICT HEADQUARTERS O 6201 S Street, Sacramento CA 95817-1899

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Frank J. Miraglia, Jr. JEW 87-750 and accuracies have been estimated for total gas based on a theoretical model applying the ideal gas law, Henry's law, and the partial pressure of water vapor. This estimate has yet tc, be verified.

Ranges and accuracles have been experimentally determined for Boron and Chloride analyses using the equipment before final installation. Listed below are the range and accuracies and the Reg. Guide 1.97 required ranges as a reference.

PASS In-Line Analysis Sample R. G. 1.97 Range Accuracy pH 1 to 13 5 to 9 1 0.3 0 to 14 1 0.5 Boron 0 to 6000 ppm 40 to 400 ppm i 20%

400 to 3600 ppm i 10%

Chloride 0 to 20 ppm 10 to 100 ppb i 20%

100 ppb to 1 ppm i 10%

1 to 10 ppm i 15%

10 to 20 ppm i 20%

Total 0 to 2000 18 to 450 cc/kg i 20%

(low range inst.)

Dissolved cc/kg 50 to 2000 cc/kg i 10%

Gases (hid h range inst.)

Interim Grab Sample On-Site Analysis Sample R. G. 1.97 Range Accuracy Boron 0 to 6000 ppm 40 to 3840 ppm i 16%

The range of the boron analysis was changed for the following reasons:

• Attempts to analyze standards of 6000 and 5600 ppm boron using the in-line ion chromatograph resulted in plugging of the 0.012 inch diameter tubing by boric acid crystals. This resulted in a requirement for tubing replacement each time the standard was run.

This demonstrated that the boron concentrations in the upper range required by Regulatory Guide 1.97 can not be measured by the in-line ion chromatograph.

• The District felt that substantial benefits would be gained in improved routine verification of operability, better operator training, and an increased level of confidence by the operators using l

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Frank J. Miraglia, Jr. May 4, 1987 JEW 87-750 PASS, by adjusting the range and accuracy of the in-line ion chromatograph so that normal operating boron concentrations as low as 50 ppm boron, which would be expected near end of core life, could be analyzed and compared to actual plant data. However, in so doing, the response of the upper end is limited to 3800 ppm.

• With regard to the range of the laboratory analysis of the interim grab sample for boron, the range of the analysis is affected by the change in dilution capability of the modified PASS. The dilution factor has been changed from range of 500:1- 1500:1, down to 200:1 -

960:1. This, in turn, reduced the range of this analysis from 12-4500 ppm as indicated in the District's March 13, 1986 letter, to 40-3840 ppm. These ranges are based on a single dilution. Multiple dilutions could extend the range of the analysis, but for all credible RCS boron concentrations, a multiple dilution reduces concentrations to or below the lower limit of detectability.

• Under accident conditions, the sources of boron that are automatically injected into the reactor coolant system are at concentrations less than 2000 ppm. The only source of concentrated boric acid is from the Concentrated Boric Acid Storage Tank which is isolated automatically.

Based on the above, the District feels that the ranges and accuracies as stated above provide pertinent data to the operator in order to adequately describe the radiological and chemical status of the reactor coolant system, and therefore, they satisfy the requirements of Criterion 10 of NUREG 0737, Item II.B.3.

This additional information is provided for inclusion into your on-going review of the Post Accident Sampling System Modifications for Rancho Seco Nuclear Generating System.

If you have any questions, please contact Masa Nakao of my staff at (209) 333-2935 extension 3905.

Sincerely, ehn E. Ward Deputy General Manager, Nuclear cc: George Kalman, NRC - Bethesda A. D'Angelo, NRC - Rancho Seco