ML20134L442
| ML20134L442 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 11/13/1996 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20134L436 | List: |
| References | |
| NUDOCS 9611210013 | |
| Download: ML20134L442 (5) | |
Text
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t UNITED STATES NUCLEAR REGULATORY COMMISSION If WASHINGTON, D.C. 20665 4001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.118 TO FACILITY OPERATING LICENSE N0. NPF-30 UNION ELECTRIC COMPANY CALLAWAY PLANT. UNIT 1 DOCKET NO. 50-483 l
1.0 INTRODUCTION
By letter dated July 18, 1996, Union Electric Company (UE), requested changes to the Technical Specifications (TS) (Appendix A to Facility Operating License No. NPF-30) for the Callaway Plant, Unit 1.
The proposed amendment would revise the surveillance requirements of TS 3/4.7.7, 3/4.9.13 and the corresponding Bases.
Specifically, the amendment would change the acceptance criteria for the testing of carbon samples from the auxiliary / fuel building emergency exhaust system charcoal adsorbers. ASTM D-3803-1989 would be adopted as the laboratory testing standard for charcoal samples from the charcoal adsorbers in the auxiliary / fuel building emergency exhaust system.
2.0 EVALVATIDH The proposed TS amendment changes the testing requirements used to determine the operability of the charcoal in the auxiliary / fuel building emargency exhaust system. The charcoal is provided to remove iodine from the air as it passes through the emergency exhaust system.
i Callaway TS Surveillance Requirements 4.7.7.b.2, 4.7.7.c, 4.9.13.b.2 and 4.9.13.c presently specify regulatory position C.6.a of Regulatory Guide (RG) 1.52, Revision 2, " Design, Testing, and Maintenance Criteria for Post Accident Engineered-Safety-Feature Atmosphere Cleanup System Air Filtration and Adsorption Units of Light-Water-Cooled Nuclear Power Plants," dated March 1978, as the requirement for the laboratory testing of the charcoal. RG 1.52 references ANSI N509-1976, " Nuclear Power Plant Air Cleaning Units and 4
Components." ANSI N509-1976 specifies that testing is to be performed in accordance with paragraph 4.5.3 of Military Specification RDT M 16-1T, " Gas Phase Adsorbents for Trapping Radioactive Iodine and Iodine Components" (year not specified) at 80*C and with a 25'c pre-and post-test sweep. The essential elements of this test are:
70 percent relative humidity (RH) for air filtration systems designed to control the RH to 70 percent (i.e., filtration systems with heaters)
A 5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> pre-test charcoal sample equilibration at 25'C and 70 percent RH A 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> injection of challenge gas at a test medium temperature of 80*C and 70 percent RH A 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> post-test sweep at 25'C and 70 percent RH Methyl iodide penetration of less than 1 percent 9611210013 961113
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fDR ADOCK 05000483 PDR 1
'J The licensee proposed to change Callaway TS Surveillance Requirements 4.7.7.b.2, 4.7.7.c, 4.9.13.b.2 and 4.9.13.c to reference ASTM D 3803-1989,
" Standard Test Method for Nuclear-Grade Carbon," as the requirement for the laboratory testing of the charcoal. ASTM D-3803-1989 is updated guidance based on ASTM D3803-1979, which is updated guidance based on RDT M 16-1T. The essential elements of the proposed TS change for testing per ASTM D 3803-1989 are:
70 percent RH A 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> pre-test thermal stabilization at 30'C A 16 hour1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> pre-test charcoal sample equilibration at 30*C and 70 percent RH i
A 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> equilibration of the sample at 30*C and 70 percent RH l
A 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> injection of challenge gas at a test medium temperature of 30*C and 70 percent RH A 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> post-test sweep at 30*C and 70 percent RH Methyl iodide penetration less than 2 percent The major differences between the current TS and the proposed TS change requirements for carbon testing are:
MAJOR DIFFERENCES Proposed Current Test Temperature 30*C 25'C, 80*C, 25'c Total Pre-Test Equilibration.
18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br /> 5 hours Methyl Iodide Penetration 2 percent 1 percent Tolerances of Test Parameters Smailer Larger These differences will be addressed individually and will be shown to be more conservative than the present TS requirements.
As stated above, the licensee proposed to challenge the representative carbon samples at 30*C rather than 80*C.
Information Notice 86-76, " Problems Noted in Control Room Emergency Ventilation Systems," indicated that laboratory testing of charcoal at a temperature higher than that expected during the course of an accident could result in an overprediction of the capability of the charcoal to remove methyl iodine. The quantity of water retained by charcoal (carbon) is dependent on temperature. Generally, the higher the temperature the less water retained. The water retained by the carben decreases the efficiency of the carbon to adsorb other contaminants. At 30*C and 95 percent.RH, carbon will retain about 40 weight percent water. At 80'C and 95 percent RH, carbon retains only about 2 to 3 weight percent water.
Therefore, the lower temperature test medium of the proposed TS will yield more conservative results than the present TS.
ASTM D 3803-1989 specifies a test temperature of 30*C for both the pre-and post-test sweep instead of the 25'C required by ANSI N509-1976. There is little difference in the adsorption behavior of carbon between these two 1
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temperatures. The 25'C parameter is more conservative. The increase from 25'C to 30*C does not represent a significant decrease in the test results.
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Pre-test humidity equilibration is achieved by sweeping air of the appropriate i
i humidity through the test carbon. The present TS reference to ANSI N509-1976 (RDT M 16-IT) requires that for new charcoal, the charcoal be equilibrated to 25'C and 70 percent RH. The methyl iodide test medium would then be instantaneously introduced at 80*C.
Testing the charcoal with such thermal l
step changes is technically incorrect because it causes condensation on the charcoal sample. Condensation on the charcoal sample itself (" wetting the bed") makes the test invalid. This.is supported by paragraph 12.41. of ASTM D-3803-1979, which states with respect to relative humidity of the test medium i
that " tests at saturation or above give'very erratic results." Because of j
this, the ASTM D-3803-1989 standard includes a 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> pre-test thermal-only stabilization at 30*C and specifies a temperature of 30*C for all phases of the test. Therefore, ASTM D-3803-1989 is a better test because it solves the problem of the formation of condensation on the charcoal sample.
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The ASTM D-3803-1989 standard is more stringent than the RDT H 16-1T standard l
since it has smaller tolerances for various parameters of the test protocol that result in more acceptable reproducibility of the test and it requires that the carbon sample be pre-test equilibrated for a much longer duration.
l The longer pre-equilibration is conservative since it will. completely saturate the representative carbon sample to the condition to which the subject charcoal adsorbers are expected to be exposed during design basis conditions.
4 During the pre-equilibration, the charcoal is exposed to a flow of air controlled at the test temperature and RH before the challenge gas is fed through the charcoal. The purpose of the pre-equilibration phase of the test is to ensure that the charcoal has stabilized at the specified test temperature and RH for a period of time which results in the charcoal adsorbing all the available moisture before the charcoal is challenged with methyl iodide. Therefore, the measured methyl iodide removal efficiency is lower than it is if pre-equilibration is not performed. The current testing at 80*C thermally regenerates-the charcoal causing the test to provide results which over predict the capability of the charcoal. Hence, the proposed testing in accordance with ASTM D-3803-1989 standard would result in a more realistic prediction of the capability of the charcoal.
The licensee proposed a higher limit for the methyl iodide penetration through carbon samples taken from the charcoal adsorbers while still claiming an adsorption. efficiency of 90 percent for radioiodine. Although the proposed 2 percent penetration acceptance criterion is less conservative than the current 1 percent. penetration, the RDT M 16-1T standard when used with a 1 percent penetration is less conservative than the ASTM D 3803-1989 standard tihen used with a 2 percent penetration because the ASTM standard is a much more stringent test.' Therefore, the staff concludes that in adequate safety margin exists when the proposed ASTM D-3803-1989 standard is used to credit a charcoal filter adsorption efficiency of 90 percent for radiciodine to conform-with the 10 CFR Part 100 and GDC 19 limits.
l The requested changes revise Callaway TS Surveillacce Requirements 4.7.6.c.2, 4.7.6.d, 4.9.13.b.2, and 4.9.13.c for charcoal filter laboratory testing such that existing test methodology in the TS is revised to reflect current NRC guidance on laboratory testing of charcoal. The staff has evaluated this change and concludes that the testing methodology proposed by the licensee adequately demonstrates the operability of charcoal in the auxiliary / fuel building emergency exhaust system and is therefore acceptable.
In the licensee's July 18, 1996 submittal, the following statements were made:
l This amendment request does not involve a change in assumption of the efficiency for the emergency exhaust system units FGG02A,B. The current analysis for the fuel handling accident and the LOCA assume a 90% efficiency. This change in test protocol and the design 1
residence time of it0.25 seconds would allow future changes to the charcoal filter efficiency of up to 95%. Any changes would be done under the criteria of 10CFR50.59.
The staff's review of the licensee's submittal did not include a review of the accuracy of this information as it did not pertain to the licensee's request; 4
i.e., it was outside the scope of the request. Therefore, approval of the amendment request does not mean the staff has reviewed and approved the licensee's position that future changes in system efficiency can be made under the criteria of 10CFR50.59.
3.0 STATE CONSULTATION
In accordance with the Comnossion's regulations, the Missouri State official was notified of the proposed issuance of the amendment.
The State official 4
had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
i The amendment changes surveillance requirements.
The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (61 FR 42285). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
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5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors:
J. Segala 4
j K. Thomas j
Date:
November 13, 1996
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