ML20151Y962
| ML20151Y962 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/06/1986 |
| From: | Reinaldo Rodriguez SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Miraglia F Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.B.3, TASK-TM RJR-86-60, TAC-60632, NUDOCS 8602130232 | |
| Download: ML20151Y962 (5) | |
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SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 S Street, P.O. Box 15830. Sacramento CA 958521830,(916) 452-3211 AN ELECTRIC SYSTEM SERVING THE HEAHT OF CALIFORNIA RJR 86-60 February 6,1986 DIRECTOR OF NUCLEAR REACTOR REGULATION ATTENTION FRANK J MIRAGLIA JR DIRECTOR PWR-B DIVISION US NUCLEAR REGULATORY COMMISSION WASHINGTON D C 20555 DOCKET 50-312 RANCHO SECO NUCLEAR GENERATING STATION UNIT NO. 1 POST ACCIDENT SAMPLING SYSTEM (PASS)
In letters dated October 13,1902, May 2 and June 17, 1983, the District submitted detailed design information on the PASS system which was being installed in the 1983 refueling outage. This design information was reviewed by the NRC. Safety evaluations dated February 15 and September 2, 1983 stated that the Rancho Seco PASS design met all eleven criteria of NUREG-0737, Item II.B.3.
In accordance with the NRC's March 14,1983 order, the PASS equipment was installed as designed during the 1983 refueling outage. Subsequent operation of the system revealed some difficulties in obtaining consistent results not detected by startup testing or design review.
Since the installation of the system, several design modifications have been implemented in an attempt to correct problems but with varying degrees of success. The consistency and repeatability of some PASS system capabilities are currently being improved. These include the boron and chloride analysis and total gas measurement for liquid samples and the isotopic analysis of the Reactor Building atmosphere sample.
Until the reliability of the in-line analysis capability can be improved, alternative analysis methods have been established based on NUREG-0737, Item II.B.3 requirements.
The changes that have been made are compared with the original PASS design on Table 1. describes the sample and analysis methods which dif fer f rom the District's October 13, 1982, May 2 and June 17, 1983 submittals.
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2 Frank J. Miraglia February 6, 1986 Further,.in discussion with Messrs. Yuhas and Cillis of Region V staff on January 27, 1986, a review of the NRC's Safety Evaluation provided on February 15-and September ' 1983, indicated that some clarification of the Rancho Seco PASS design e r be necessary to avoid misinterpretation of the system capabilities. Au.chment 2 provides information on the three areas that were discussed. With the changes' described in Attachment 1, the District considers that the Post Accident Sampling System at Rancho Seco ftJll satisfies the requirements of NUREG-0737, ' Item II.B.3.
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Attachment to RJR 86-60 TABLE 1 RANCHO SECO POST ACCIDENT SAMPLING SYSTEM (PASS)
ORIGINAL CURRENT BACKUP CHANGES TO PASS SYSTEM PASS SAMPLE SAMPLE DESIGN METHOD METHOD REACTOR COOLANT Isotopic In-line In-line Off-Site Total Gas In-line In-line calculation A calculational method using RB hydrogen concentration and in-core temperature will be used as a backup.
pH In-line In-line Off-Site Conductivity In-line In-line Off-site Boron In-line Grab on-site Off-Site The necessary lab equipment & chemicals have been provided for on-site analysis of the grab sample.
Chloride in 4-days In-line Off-site Not Reg'd The first undiluted backup grab sample will be used for off-site analysis within 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />.
Oxygen Off-site Off-site Not Reg'd The off-site analysis will be performed on a depressurised grab sample.
lu Ci/g to 10 Ci/g Yes Yes Yes Diluted samples will be used for high activity on-site analysis.
3 hr & <5 rem Each Each N/A See Attachment ~1 for additional information.
CONTAINMENT ATMOS.
Isotopic In-line Grab on-site Calculation A calculation using RB hi-range area monitors R15049/15050 & isotopic mix vs R/hr graphs will be used as a backup.
Hydrogen H Monitors H Monitors Grab on-site The backup grab sample will be analyzed on-site.
3 hr & <5 rem Yes Yes Yes The grab samples for isotopic and hydrogen will be analyzed on-site.
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CHANGES TO RANCHO SECO POST ACCIDENT SAMPLING SYSTEM 1.
Boron - RCS Liquid (Item II.B.3, Criterion 7)
The District's October 13, 1982 submittal committed to use an in-line ion chromatograph for boron analysis.
Difficulties in consistently loading the ion chromatograph has resulted in varying analytical results.
An alternate method of analyzing for boron has been implemented which provides for a grab sample analysis on-site using an ion chromatograph.
The capability to obtain a backup grab sample for offsite analysis is also available.
2.
Chlorides - RCS liquid (Item II.B.3, Criterion 5)
The District's October 13, 1982 submittal committed to use an in-line ion chromatograph for chloride analysis. The chromatograph is the same one used for the boron analysis and exhibits the same variable analysis results.
On this basis the District has changed and implemented its chloride sample and analysis to use the first grab sample for off-site laboratory analysis within the 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> as allowed in Criterion 5 of II.B.3.
3.
Radioisotopic Analysis - Reactor Building Atmosphere (Item II.B.3, Criterion 2a)
The District's October 13, 1982 letter. committed to in-line radioisotopic analysis of the R.B. atomsphere.
The gamma spectrometer used for radioisotopic analysis experiences liquid intrusion from the sample lines which interferes with the analytical results.
An alternative method of determining radioisotopes in the R.B.
atmosphere has been implemented using a grab sample that is analyzed on-site. Should the problems with the in-line analysis be resolved in the future, this grab sample will serve as a backup.
The District is also developing a second alternate method of determining the isotopic mix in the Reactor Building atmosphere.
This method correlates-the Feactor Building high-range area monitor reading to a graph of isotopic raix vs R/hr for various times af ter an accident..
4.
Total Gas Because the amounts of dissolved gases in the reactor coolant during normal plant operations are at the low end of the equipment range
( 100cc/kg), accurate total gas determinations have nat been reliably demonstrated. Modifications are being made to improve the system's operating characteristics. An alternate' calculational method for determining total gas is being developed which uses the Reactor Building hydrogen concentration and incore temperature.
This method would only be used as a backup method for total gas.
ADDITIONAL INFORMATION POST ACCIDENT SAMPLING SYSTEM AT RANCHO SECO Criterion 1 The licensee shall have the capability to promptly obtain reactor coolant samples and containment atmosphere samples. The combined time allotted for sampling and analysis should be 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> or less from the time a decision is made to take a sample.
Additional Information:
a) The capability to obtain and analyze samples within three (3) hours is applied to one sample, either a reactor coolant sample, a Reactor Building emergency sump sample or Reactor Building atmosphe*e sample.
Wording in the SER implies both the liquid sample and gas.41ple are included in the three hour time limit.
b) The reacto. "olant sample wil' be obtained from the 8 loop cold leg drain via a ;onnection to the pressurizer liquid sample line. Although the capability exists to draw a sample from the pressurizer, the procedures for PASS only takes samples from the B loop cold leg.
The pro,surizer sample line provided a convienent penetration of the Reactor Building tut a pressurizer sample may not be representative of the circulating reactor coolant during an accident.
Criterion 8 If in-line monitoring is used for any sampling and analytical capability specified herein, the licensee shall provide backup sampling through grab samples, and shall demonstrate the capability of analyzing the samples.
Established planning for analysis at offsite facilities is acceptable.
Equipment provided for backup sampling shall be capable of providing at least one sample per day for 7 days following onset of the accident, and at least one sample per week until the accident condition no longer exists.
Additional Information:
Total gas is measured using expansion of the pressurized reactor coolant sample between two known volumes and measurement of pressure changes. Since this was considered a physical measurement and not an in-line chemical analysis, Criterion 8 was interpretted as not being applicable.
Therefore, the PASS was not designed with any provision for a pressurized grab sample for total gas. This interpretation was reinforced by the wording in clarification (4) which indicates that pre:;urized reactor coolant samples are not required if dissolved gases can be quantified with unpressurized reactor coolant sample. The recommended oxygen analysis in Criterion 4 will be performed on the depressurized grab samole by the of f-site laboratory for dissolved oxygea.
As indicated in Attachment 1, a calculational method for determining total gas is being developed as a backup.