ML20217K832
| ML20217K832 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 04/27/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20217K825 | List: |
| References | |
| NUDOCS 9805040149 | |
| Download: ML20217K832 (6) | |
Text
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.y gk UNITED STATES 0
' g NUCLEAR REGULATORY COMMISS!ON g
%.....,o#g WASHINGTON, D.C. 20066-0001 j
g SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.125 TO FACILITY OPERATING LICENSE NO. NPF-11 AND AMENDMENT NO 110 TO FACILITY OPERATING LICENSE NO. NPF-18 COMMONWEALTH EDISON COMPANY LASALLE COUNTY STATION. UNITS 1 AND 2 DOCKET NOS. 50-373 AND 50-374
1.0 INTRODUCTION
By letter dated September 26,1997, as supplemented on April 7,1998, Commonwealth Edison Company (Comed, the licensee) requested changes to the Technical Specifications (TS) for LaSalle County Station, Units 1 and 2. The proposed changes would revise the TS to (1) prohibit the simultaneous opening of the drywell and suppression chamber purge system isolation valves, (2) upgrade the ventilation filter testing program to the latest industry standards, and (3) specify that the auxiliary electric equipment room is required to be habitable during design bases accidents. This amendment approves a portion of the request, specifically, changes to TS 3.6.1.8, "Drywell and Suppression Chamber Purge System," and surveillance requirement (SR) 4.6.5.3, " Standby Gas Treatment System," and adds a new TS 6.2.F 8, " Ventilation Filter Testing Program." The remaining portions of the amendment request will be addressed in separate correspondence. The April 7,1998, submittal provided additional clarifying information that did not change the initial proposed no significant hazards consideration determination.
2.0 EVALUATION 2.1 Drvwell and Suporession Chamber Purae System TS 3.6.1.8 "Drywell and Suppression Chamber Purge System" allows for inerting, deinerting, and pressure control with the drywell and/or suppression chamber purge supply and exhaust isolation valves open. The wording of the current TS and the current operating procedures allow simultaneous purging or venting of the drywell and suppression chamber. The licensee has determined that with both valves open, a drywell floor bypass path would be created (from the drywell, through the drywell purge valves, through the suppression chamber main purge valves, into the suppression chamber) which would reduce the pressure suppression function of the suppression pool during a loss-of-coolant accident (LOCA). The evaluations of steam bypass of l
the suppression pool assume a maximum allowable leakage area of 0.03 square feet based on suppression chamber vacuum breaker valve seat leakage (this evaluation assumed that the drywell and suppression chamber purge isolation valves were closed). The amount of bypass that would result from both valves being open simultaneously would be greater than the design l
basis leakage of 0.03 square feet. The licensee has proposed to revise TS 3.6.1.8 to allow only one of the isolation valves to be open at a time, thereby ensuring that the only bypass will be through vacuum breaker seat leakage, consistent with the plant's design basis. TS 3.6.1.8 will 9805040149 900427 PDR ADOCK 05000373 PDR l
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y r.3 be revised to delete the option to open the drywell and suppression chamber purge system isolation valves.
The proposed change will have no effect on plant safety since adequate purging or venting capability will still exist with the proposed restriction. The proposed change will improve plant safety and make the TS consistent with the design basis and is, therefore, acceptable.
2.2 Ventilation Filter Testina Prooram The proposed amendments change the SR for the Standby Gas Treatment (SBGT) System as stated in TS 4.6.5.3. The licensee proposes to relocate the SR discussed below from the current TS to the Ventilation Filter Testing Program which is being added as Section 6.2.F.8 of the Administrative Controls section of the TS. The relocation of these surveillances is consistent with the Standard Technical Specifications (STS) for General Electric Plants, BWR/6 (NUREG-1434). The Ventilation Filter Testing Program contains the surveillances currently located in TS 4.6.5.3, bist will reference updated industry standards.
2.2.1 Test Freauency The current TS specify tests to be performed at the following frequencies: every 18 months; after every 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of operation; following maintenance on the filter; and, after fire, painting or chemical release in a ventilation zone. Proposed TS 6.2.F.8 states that tests will be conducted at the frequencies specified in Regulatory Guide (RG) 1.52, Revision 2, " Design, Testing, and Maintenance Criteria for Postaccident Engineered-Safety-Feature Atmosphere Cleanup System Air Filtration and Adsorption Units of Light-Water-Cooled Nuclear Power Plants." This change is acceptable because RG 1.52 specifies the same testing frequencies.
2.2.2 Inolace Filter Testino Current TS 4.6.5.3.b.1 requires verification that the inplace testing of the high-efficiency particulate air (HEPA) filter and charcoal adsorber satisfies the acceptance criteria and uses the test procedures of RG 1.52, Revision 2. It also requires that a flow rate of 4000 cfm 110 percent is maintained when testing in accordance with ANSI N510-1975. These requirements are being relocated to Section 6.2.F.8 as discussed below.
Proposed TS 6.2.F.8.a requires that an inplace test of ths HEPA filters in the SBGT system show a penetration and system bypass of less than 0.05 percent when tested in accordance with ASME N510-1989. The reference to the updated ASME standard is acceptable because it is consistent with the STS. The acmptance value of 0.05 percent for the SBGT system is consistent with RG 1.52, Revision 2 guidance and is acceptable.
Proposed TS 6.2.F.8.b provides the maximum penetrat!on and system bypass for an in place test of the charcoal adsorbers. The proposed limit is 0.05 percent for SBGT systems. This limit is consistent with RG 1.52, Revision 2, and is acceptable. Proposed TS 6.2.F.8.s and b require testing at a flowrate of13600 and $4400 cfm. This is consistent with the current TS requirement of 4000 cfmi10 percent.
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-e 2.2.3 Laboratory Testino Current TS 4.6.5.3.b.2 and 4.6.5.3.c require that laboratory analyses of the cart >on samples use the test procedures of and meet the acceptance criteria of Regulatory Position C.6.a of RG 1.52, Revision 2. Regulatory Position C.6.a refers to Table 2 of RG 1.52. Table 2 references Test 5.b of Table 5-1 of ANSI N509-1976," Nuclear Power Plant Air-Cleaning Units and Components."
Test 5.b references the test method from paragraph 4.5.3 of Military Specification RDT M 16-1T,
" Gas Phase Adsort>ents for Trapping Radioactive lodine and lodine Components"(date not indicated), but specifies that the test is to be conducted at 80 degrees Celsius and 95-percent relative humidity (RH) with proloading and postloading sweep at 25 degrees Celsius. This test is referred to as the "25-80-25 test." The essential elements of this test are as follows:
70-percent RH for air filtration systems designed to control the RH to 70-percent, 5-hour pre-equilibration (pre-sweep) time, with air at 25 degrees Celsius and 70-percent e
RH, e 2-hour challenge, with gas at 80 degrees Celsius and 70-percent RH, and A 2-hour elution (post-sweep) time, with air at 25 degrees Celsius and 70-percent RH.
e The licensee has proposed to relocate these surveillances to TS 6.2.F.8.c. The proposed SR also requires that samples be obtained as described in RG 1.52, Revision 2, but specifes that the samples be tested in accordance with ASTM D3803-1989, " Standard Test Method for Nuclear-Grade Activated Carbon." ASTM D3803-1989 is updated guidance based on an NRC verification and validation effort on ASTM D3803-1979, which is updated guidance based on RDT M16-1T. The essential elements of the proposed TS change for testing per ASTM D3803-1989 are:
- 70-percent Rh,or air filtration systems designed to control the RH to 70-percent, e 2-hour thermal stabilization, with air at 30 degrees Celsius, e 16-hour pre-equilibration (pre-sweep) time, with air at 30 degrees Celsius and 70-percent RH, 2-hour equilibration time, with air at 30 degrees Celsius and 70-percent RH, e
e 1-hour challenge, with gas at 30 degrees Celsius and 70-percent RH, and 1-hour elution (post-sweep) time, with air at 3O' degrees Celsius and 70-percent RH.
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The m@r differences between the current and proposed TS requirements for carbon testing are:
MAJOR DIFFERENCES Proposed TS Current TS Pre 4quilibration 30'C 25'C (Pre-Sweep) Temperature Challenge Temperature 30'C 80*C Elution (Post-Sweep) 30*C 25'C Temperature 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 Tolerances of Test Smaller Larger Parameters i
The discussion below demonstrates that these differences make the proposed TS more conservative than the present TS requirements.
ASTM D3803-1989 challenges the representative charcoal samples at 30 degrees Celsius rather than at 80 degrees Celsius. The quantity of water retained by charcoal is dependent on temperature, with less water being retained as the temperature rises. The water retained by the charcoal decreases its efficiency in adsorbing other contaminants. Because most chucoal is i
anticipated to be challenged at a temperature closer to 30 degrees Celsius rather than 80 degrees Celsius, the lower temperature test condition of ASTM D3803-1989 will yield more realistic results than a test performed at 80 degrees Celsius.
ASTM D3803-1989 specifies a test temperature of 30 degrees Celsius for both the pre-and j
post-test sweep rather than 25 degrees Celsius. There is little difference in the adsorption behavior of charcoal between these two temperatures. A temperature of 25 degrees Celsius is more conservative; however, the increase from 25 degrees Celsius to 30 degrees Celsius does not represent a significant variation in the test results.
ASTM D3803-198g provides results which are reproducible compared to RDT M 16-1T because it has smaller tolerances on various test parameters, and it requires that the charcoal sample be pre-equilibrated for a much longer period. The longer pre-equilibration time is more conservative 4
because it will completely saturate the representative charcoal sample until it is in the condition to which the subject charcoal adsorbers are expected to be exposed during design-basis condebons. During the pre-equilibration, the charcoalis 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 sped 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. 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.
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Proposed TS 6.2.F.8.c also requires testing of charcoal samples at a temperature of 30 degrees Celsius, a RH of 70 percent and a face velocity of 40 feet / minute for the SBGT system. The SBGT system charcoal adsorber has a depth of 8 inches. At a residence time of.25 second for each 2 inches of depth, per RG 1.52, this equals a total residence time of 1 second. The filters
- are designed for a residence time of 2 seconds at a face velocity of 20 fpm. The licensee proposed to test at a face velocity of 40 fpm to be consistent with RG 1.52, Revision 2.
Therefore, the proposed testing will provide more conservative results relative to the design flow and is acceptable.
Per RG 1.52, the SBGT charcoal bed (with a depth of >4 inches) has an efficiency of 99 percent.
The licensee's proposed acceptance criteria is a methyl lodido penetration of less than 0.5 -
percent. The proposed acceptance criteria includes a safety factor of two which provides the staff a degree of assurance that, at the end of the operating cycle, the charcoal will be capable of performing at a level at least as good as that assumed in the licensee's dose analysis. This factor of safety is acceptable based on the accuracy of test results obtained using the ASTM D3803-1989 standard. Based on a safety factor of two, the allowable penetration as stated in the proposed TS is 0.5 percent for SBGT.
The staff has reviewed the proposed test methods and acceptance criteria in TS 6.2.F.8.c and finds them acceptable.
2.2.4 Other Surveillances Current TS 4.6.5.3.d.1 requires verification that the pressure drop across the combined HEPA filters and charcoal adsorber banks is less than or equal to eight inches water gauge while operating the filter train at a flow rate of 4000 cfm 110 percent. This surveillance is being relocated to proposed TS 6.2.F.8.d. The proposed TS requires a demonstration that the pressure drop across the combined moisture separator, heater, profilter, HEPA filters and the charcoal adsorbers is less than 8 inches water gauge for the SBGT system when tested at a flowrote of >3600 cfm and $4400 cfm. This is consistent with the current TS and is acceptable.
Current TS 4.6.5.3.d.3 requires verification that the heaters dissipate 2312.0 kW when tested in accordance with ANSI N510. Proposed TS 6.2.F.8.e requires that the heaters for the SBGT system dissipate between 21 and 25 kW when tested in accordance with ASME N510-1989.
These limits are consistent with those in the current TS and are acceptable.
2.2.5 Conclusion The Ventilation Filter Testing Program proposed by the licensee is consistent with the program in NUREG-1434, STS General Electric Plants, BWR/6, Section 5.5.8. The requested changes to TS 4.6.5.3 revise charcoal filter testing such tt,3t existing flawed test methodology will reflect the l
current industry standard. The staff has evaluated these changes and concludes that the testing methodology proposed by the licensee adequately demonstrates the operability of the SGTS and is, therefore, acceptable.
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l 6-2.3 Editorial Channes The paragraph numbering and indentation of TS 6.2.F.7 are revised for consistency with the remainder of TS 6.2.F.
3.0 STATE CONSULTATION
l In accordance with the Commission's regulations, the lilinois State official was notified of the proposed issuance of the amendments. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change surveillance requirements. The NRC staff has determined that the amendments in/olve no l
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 amendments involve no significant hazards consideration, and there has been no public comment on such finding (62 FR 61840). Accordingly, the amendments meet the eligibility I
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 amendments.
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 amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: D. Skay Date:
April 27, 1998 4
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