ML20216C726
| ML20216C726 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 05/13/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20216C684 | List: |
| References | |
| NUDOCS 9805190396 | |
| Download: ML20216C726 (8) | |
Text
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y UNITED STATES g,
j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 30666-0001 os...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION i
l RELATED TO AMENDMENT NO.126 TO FACILITY OPERATING LICENSE NO. NPF-11 AND AMENDMENT NO. iii TO FACILITY OPERATING LICENSE NO. NPF-11 COMMONWEALTH EDISON COMPANY LASALLE COUNTY STATION. UNITS 1 AND 2 DOCKET NOS. 50-373 AND 50-374
1.0 INTRODUCTION
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By 1stter dated September 26,1997, as supplemented on April 7,1998, and May 1,1998, l
Comrronwealth Edison Company (Comed, the licensee) requested changes to the Technical Specifications (TS) for LaSalle County Station, Units 1 and 2. Revisions related to drywell and suppression chamber purge and the editorial changes requested in the September 26,1997, application were approved and issued under Amendment Nos.125 and 110 dated April C,1998.
This safety evaluation discusses the remaining requested changes. Specifically, these amendments revise TS 3/4.7.2, " Control Room and Auxiliary Electric Equipment Room Emergency Filtration System" and TS 6.2.F.8, " Ventilation Filter Testing Program". The changes consolidate the testing requirements for these systems into a single Ventilation Filter Testing Program and revise the filter efficiencies and system flow rates credited in the Loss-of-Coolant Accident (LOCA) analysis. The proposed changes also upgrade the ventilation filter testing program to current industry standards and specify that the Auxiliary Electric Equipment Room (AEER)is required to be habitable during design basis accidents. The April 7 and May 1,1998, i
submittals provided additionalinformation that did not change the initial proposed no significant hazards consideration determination.
2.0 EVALUATION 2.1 Ventilation Filter Testing Program The proposed amendments change the surveillance requirements (SR) for the control room and AEER emergency filtration systems as stated in TS 4.7.2. The licensee proposed to relocate the SR discussed below for the control room and AEER emergency filtration system (CREF) from the current TS to the Ventilation Filter Testing Program in Section 6.2.F.8 of the Administrative L
Controls section of the TS. In addition, the licensee proposed to add new SR discussed below for the control room recirculation filters (CRRF) and the AEER recirculation filters (AEERRF).
The relocation and addition of these surveillances is consistent with the Standard Technical l-Specifications (STS) for General Electric Plants, BWR/6 (NUREG-1434). The Ventilation Filter l
Testing Program contains the surveillances currently located in TS 4.7.2, but will reference updated industry standards.
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i 2.1.1 Test Frequency 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 roiease in a ventilation zone. Proposed TS 6.2.F.8 states that tests will be conducted at the fre.1uencies specified in Regulatory Guide (RG) 1.52, Revision 2, " Design, Testing, and Maintenance Criteria for Postaccident Engineered-Safety-Feature Atmosphere Cleanup System Air Filtrati'>n and Adsorption Units of Light-Water-Cooled Nuclear Power Plants." This change is acceptable because RG 1.52 specifies the same testing frequencies.
2.1.2 inplace Filter Testing Current TS 4.7.2.b.1 requires verification that the inplace testing of the high-efficiency particulate air (HEPA) filter and charcoal adsorber for the CREF satisfies the acceptance criteria and uses the test procedures of RG 1.52, Revision 2. In addition, current TS 4.7.2.b.3 requires that a flow rate of 4000 cfm 110 percent be 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 the HEPA filters in the CREF show a penetration and system bypass of less than 0.05 percent when tested in accordance with ASME N510-1989 at a flowrate of13600 and $4400 cfm. The reference to the updated ASME standard is acceptable because it is the latest version of the standard to be endorsed by the NRC and is consistent with the STS. The acceptance value of 0.05 percent for the CREF is consistent with RG 1.52, Revision 2, guidance and is acceptable. The proposed flowrate is acceptable because it is consistent with the current TS requirement of 4000 cfm 110 percent.
Proposed TS 6.2.F.8.b provides the maximum penetration and system bypass for an inplace test of the charcoal adsorbers when tested in accordance with ASME N510-1989. The proposed limit is 0.05 percent for the CREF at a flowrate of13600 and 14400 cfm. The acceptance value of 0.05 percent for the CREF is consistent with RG 1.52, Revision 2, guidance and is acceptable.
The proposed flowrate is acceptable because it is consistent with the current TS requirement of 4000 cfm 110 percent.
The licensee also proposed to add new SRs in TS 6.2.F.8.b for the CRRF and the AEERRF for inplace tests of the charcoal adsorbers. The proposed maximum penetration and system bype:::
is two percent for the CRRF at a flowrate of118000 and $28900 cfm. The proposed limit is two percent for the AEERRF at a flowrate of114000 and $22800 cfm. The proposed accel.tance value of two percent for the CRRF and the AEERRF is acceptable because it includes the design leakage through the charcoal filter bypass damper, in addition, the licensee adjusted the charcoal filter efficiencies credited in the dose analysis to account for the two percent bypass by conservatively assuming five percent bypass. The proposed CRRF and AEERRF flowrates are acceptable because they are in agreement with their design rated flowrates.
2.1.3 Laboratory Testing Current TS 4.7.2.b.2 and 4.7.2.c require that laboratory analyses of the carbon 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
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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 M16-1T,
" Gas Phase Adsorbents for Trapping Radioactive lodine and lodine Components"(date not indicated), but specifies that the test is to be conducted at 80 degrees Celsius ('C) and 95 percent relative humidity (RH) with preloading and postloading sweep at 25'C. 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, e
5-hour pre-equilibration (pre-sweep) time, with air at 25*C and 70 percent RH, e
2-hour challenge, with gas at 80 C and 70 percent RH, and e
a 2-hour elution (post sweep) time, with air at 25 C 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 specifies that the samples be tested in accordance with ASTM D3803-1989, " Standard Test Method for Nuclear-Grade Activated Carbon" at 30'C and 70 percent RH. ASTM D3803-1989 is updated guidance based on an NRC verification and validation effort on ASTM D3803-1979, which is l
updated guidance based on RDT M16-1T. The essential elements of the proposed TS change for testing per ASTM D3803-1989 are*
i 70-percent RH for air filtration systems designed to control the RH to 70 percent, e
e 2-hour thermal stabilization, at 30*C, e 16-hour pre-equilibration (pre-sweep) time, with air at 30 C and 70 percent RH, 2-hour equilibration time, with air at 30 C and 70 percent RH, e
1-hour challenge, with gas at 30*C and 70 percent RH, and e
1-hour elution (post sweep) time, with air at 30'C and 70 percent RH.
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The major differences between the current and proposed TS requirements for carbon testing are:
MAJOR DIFFERENCES Proposed TS Current TS Pre-Equilibration 30'C 25'C (Pre-Sweep) Temperature Challenge Temperature 30'C 60'C Elution (Post-Sweep) 30'C 25'C Temperature Total Pro-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 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 C rather than at 80*C.
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 charcoalis anticipated to be challenged at a temperature closer to 30*C rather than 80'C, the lower temperature test condition of ASTM D3803-1989 will yield more realistic results than a test performed at 80 C.
ASTM D3803-1989 specifies a test temperature of 30'C for both the pre-and post-test sweep rather than 25'C. There is little difference in the adsorption behavior of charcoal between these two temperatures. A temperature of 25*C is more conservative; however, the increase from 25'C to 30*C does not represent a significant variation in the test results.
ASTM D3803-1989 provides results which are reproducible compared to RDT M16-1T 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 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 conditions. 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. Tlw 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 res:.its in the charcoal adsorbing all the available moisture before the charcoalis 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.
Performing the laboratory test of the charcoal samples at 70 percent RH is based on the CREF, CRRF, and AEERRF being designed to maintain the RH of the air stream entering the charcoal to s70 percent under worst case design basis conditions. The CREF utilizes heaters to maintain the air stream at s70 percent RH. This is consistent with the guidance provided in RG 1.52, Revision 2, and is acceptable. The licensee provided Calculation L-001119 in Attachment E of
. the September 26,1997, letter to demonstrate that the air entering the CRRF and AEERRF charcoal filters will be maintained at s70 percent RH. In addition to reviewing this calculation, the staff performed its own independent calculation without taking credit for the additional heat i
provided by the fan motors. Based on review of the licensee's calculation and the staff's independent calculation, the staff concludes that the air entering the CRRF and AEERRF charcoal filters will be maintained at s70 percent RH under worst case design basis conditions.
Proposed TS 6.2.F.8.c also requires laboratory testing of charcoal samples at a face velocity of 40 fpm for the CREF and 80 fpm for the CRRF and AEERRF. The face velocity of 40 fpm for the CREF is consistent with RG 1.52, Revision 2, guidance and is acceptable. The face velocity of i
80 fpm for the CRRF is based on the CRRF design rated flow of 26340 cfm. The face velocity of 80 fpm for the AEERRF is based on the AEERRF design rated flow of 31300 cim. Therefore, testing the CRRF and AEERRF charcoal samples at a face velocity of 80 fpm is acceptable i
because it is consistent with the face velocity of the air that will pass over the installed charcoal at the system design rated flowrate.
In addition, proposed TS 6.2.F.8.c requires that laboratory testing of charcoal samples show an acceptable methyl iodide penetration. In the licensee's dose analysis, the CREF, CRRF and AEERRF charcoal beds (each with a depth of two inches) are credited with a filter efficiency of 95 percent,70 percent, and 70 percent, respectively. The licensee's proposed acceptance criteria is a methyl iodide penetration of less than 2.5 percent for the CREF and less than 15 percent for both the CRRF and the AEERRF. The proposed acceptance criteria includes a safety factor of two which provides the staff with a degree of assurance that, at the end of the i
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.
The staff has reviewed the proposed test methods and acceptance criteria in TS 6.2.F.8.c and finds them acceptable.
2.1.4 Other Ventilation Filter Testing Program Surveillances Current TS 4.7.2.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, prefilter, HEPA filters and the charcoal adsorbers is less than eight inches water gauge for the CREF when tested at a flowrate of13600 cfm and 54400 cfn., three inches water gauge for the CRRF when tested at a flowrate of118000 and $28900 cim, and three inches water gauge for the AEERRF when tested at a flowrate of114000 and 522800 cfm. The CREF filter unit has a prefilter, upstream HEPA filter, charcoal filter, and downstream HEPA filter. The eight inches water gauge for the CREF is based on two inches water gauge per component in the filter unit. The eight inches water gauge for the CREF is consistent with the current TS and is acceptable. The filter units for the CRRF and AEERRF both have a prefilter and a charcoal filter. The standard convention of two inches water gauge per component in the filter unit would result a total pressure drop of four inches water gauge. However, preliminary testing demonstrated that the CRRF and AEERRF can only maintain the TS required flowrates at a maximum of three inches water gauge. As a result, three inches water gauge for the CRRF and AEERRF was chosen in the proposed TS. The staff noted
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- that, in its May 1,1998 letter, the licensee stated it will test the CRRF and AEERRF prior to declaring the systems operable by simulating a pressure drop of three inches water gauge across the combined profilter and adsorber and verifying that the flowrate through the filters is greater than the TS minimum flowrate. The three inches water gauge for the CRRF and AEERRF is acceptable because it will ensure that the systems can maintain the TS required flowrates by ensuring that the filters are replaced when they are dirty.
Current TS 4.7.2.d.3 requires verification that the heaters dissipate 2012.0 kW when tested in accordance with ANSI N510-1975. This surveillance is being relocated to proposed 1
TS 6.2.F.8.e. The proposed TS requires that the heaters for the CREF system dissipate l
between 18 and 22 kW when tested in accordance with ASME N510-1989. These limits are consistent with those in the current TS and are acceptable.
2.1.5 Conclusion l
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 that the current industry standard wG replace the l
existing flawed test methodology. The staff has evaluated these changes and co.icludes that the testing methodology proposed by the licensee adequately demonstrates the operability of the CREF, CRRF, and AEERRF and is, therefore, acceptable.
2.2 Other Changes Current TS 4.7.2.a requires verification at least once per 31 days on a staggered test basis by l
initiating, from the control room, flow through the HEPA filters and charcoal adsorbers of the CREF and verifying that the train operates for at least 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> with the heaters operable.
l Proposed TS 4.7.2.s requires the following to be performed at least once per 31 days on a staggered test basis: (1) operate each CREF for greater than or equal to 10 continuous hours with the heaters operating, and (2) manually initiate flow through the CRRF and AEERRF for at least 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />. The proposed TS includes the requirements of the current TS and adds the additional requirement of manually initiating the CRRF and AEERRF and is, therefore, I
acceptable.
I Current TS 4.7.2.d.2 requires verification that on (a) outside air smoke detection. and (b) air intake radiation monitors actuation test signals, the CREF filter train automatically switches to the pressurization mode of operation and the control room is maintained at a positive pressure of 1/8 inch water gauge relative to the adjacent areas during emergency train operation at a flow rate less than or equal to 4000 cfm. Proposed TS 4.7.2.d.2 requires verification that on (a) outside air smoke detection, and (b) air intake radiation monitors actuation test signals, the CREF filter train automatically switches to the pressurization mode of operation. It also requires, upon manual initiation of flow through the CRRF and AEERRF, verification that the control room and auxiliary electric equipment rooms are maintained at a positive pressure greater than or equal to 1/8 inch water gauge relative to the adjacent areas during emergency train operation at a flow rate less than or equal to 4000 cfm. The proposed TS adds the additional requirement of manually initiating the CRRF and.;EERRF while the surveillance is being performed to accurately reflect the alignment during an accident. In addition, the proposed TS includes the requirement of maintaining the auxiliary electric equipment rooms at a positive pressure and is, therefore, acceptable.
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I The licensee also proposed to revise TS 3.7.2 Bases to specifically identify that the CRRF and AEERRF are required for system operability. The staff reviewed the proposed Bases changes and finds them acceptable, i
l 2.3 Dose Calculations l
The licensee's proposal revises the filter officiencies (adjusted for bypass) and system flow rates l
credited in the LOCA analysis, in addition, the TS are revised to clarify that the habitability requirements of 10 CFR Part 50, Appendix A, General Design Criteria (GDC) 19 and, therefore, l
the ventilation system operability requirements in the TS apply to the AEER as well as the control room.
The licensee provided calculation L-001166, Revision 2, " Post LOCA Control Room, Auxiliary Electric Equipment Room, and Offsite Doses" that documents the expected radiation doses that would be received by individuals off site and in the control room and Auxiliary Electric Equipment Room from a design basis LOCA. This calculation reflects the licensing basis assumptions with I
revised ventilation system parameters consistent with the proposed TS change. In addition, the licensee took credit for containment suppression pool scrubbing of the radioactive source term l
and the use of the revised dose conversion factors found in Publication 30 of the Intemational Commission on Radiation Protection. These assumptions are consistent with current NRC staff positions that were not available during LaSalle's initiallicensing. Scaling factors were applied to the calculated doses to adjust the results for the differences in the isotopic spectrums between the current design basis source term and Siemens (extended bum-up) fuei source term, which the licensee intends to use in the future.
The licensee's calculation considered the dose contributions from the release of radioactive materials due to primary containment leakage, Emergency Core Cooling Systems (ECCS) leakage, and Main Steam Isolation Valve (MSIV) leakage. Primary containment and ECCS leakage was assumed to be contained in the secondary containment and processed through the Standby Gas Treatment System prior to release from the 370 foot stack as an elevated release.
Consistent with LaSalle's current design ~ asis, IVSIV leakage was assumed to bypass secondary o
containment through the steam piping and MSIV :frain lines. Holdup and plate out of the radioiodines in the steam system and condenser are credited before the materials are assumed to be released from the Turbine Building as a ground level release.
The calculational models for the doses to plant operators take credit for radiolodine removal by the recirculation filter units in both the control room and the AEER ventilation systems. These filter units are bypassed during normal operation and do not automatically initiate during an isolation signal. The licensee assumes it would take a maximum of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for operators to manually initiate ventilation flow through these recirculation filter units.
The NRC staff reviewed the licensee's calculational models and assumptions, in addition, the staff performed several independent confirmatory calculations to verify portions of the licensee's dose assessment. The radiological consequences as analyzed by the licensee are well within the dose criteria of 10 CFR Part 100 and 10 CFR Part 50, Appendix A, GDC 19.
The staff concludes that the licensee has demonstrated with reasonable assurance that the I
LaSalle design (as modified by this action) will meet the Acceptance Criteria of the Standard I
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" Review Plan (NUREG-0800) with respect to the radiological consequences to offsite individuals and plant operators during a design basis LOCA, and is, therefore, acceptable.
3.0 STATE CONSULTATION
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 j
component located within the restricted area as defined in 10 CFR Part 20 and change i
surveillance requirements. The NRC staff has determined that the amendments involve 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 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 criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b),
no environmentalimpact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
5.0 CONCLUSION
I 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 Contributors: R. Pederson J. Segala Date: May 13, 1998 1
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