ML20056G237
| ML20056G237 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 08/17/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20056G236 | List: |
| References | |
| NUDOCS 9309020292 | |
| Download: ML20056G237 (4) | |
Text
{{#Wiki_filter:i l r l I)D1 k UNITED STATES l Qig j NUCLEAR REGULATORY COMMISSION f gv j WASHINGTON, D C. 20555-0001 1 l SAFETY EVALVATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.188 TO FAClllTY OPERATING LICENSE DPR-57 [ AND AMENDMENT NO.127 TO FAClllTY OPERATING LICENSE NPF-5 GEORGIA POWER COMPANY. ET AL. EDWIN I. HATCH NUCLEAR PLANT. UNITS 1 AND 2 DOCKET NOS. 50-321 AND 50-366
1.0 INTRODUCTION
r By letter dated October 19, 1992, as supplemented May 3 and July 27, 1993, Georgia Power Company, et al. (GPC or the licensee), proposed license i amendments to change the Technical Specifications (TS) for the Edwin I. Hatch Nuclear Plant, Units 1 and 2. The proposed changes would remove the main steam line radiation monitor (MSLRM) reactor scram and group isolation functions. The licensee referenced the BWR Owners Group (BWROG) topical i report NEDO-31400, " Safety Evaluation for Eliminating the BWR MSIV Closure Function of the MSLRM." Furthermore, the licensee's request proposed revisions to the hydrogen water chemistry footnotes and changes to an action statement concerning the offgas post treatment monitors. The May 3 and July 27. 1993, letters provided clarifying information that did not change the initial proposed no significant hazards consideration determination. 2.0 EVALVATION l The licensee referenced BWROG topical report NED0-31400 in support of its request to eliminate the MSLRM scram and group isolation functions. In the topical report, GE analyzes a control rod drop accident (CRDA) where the main l steam line high radiation isolation is eliminated. The resulting radiological l exposures are small fractions of 10 CFR 100 limits. The topical report received NRC approval in a Safety Evaluation Report dated May 15, 1991. To j ensure that the assumptions of NED0-31400 are bounding for Hatch Units 1 and 2, GPC requested that GE perform an analysis specific to the plant. The I dose rates for Hatch Units 1 and 2 that result from the elimination of the l scram and MSIV isolation functions are also small fractions of 10 CFR 100 I limits. The accident doses calculated by GE in support of this amendment request utilized a methodology, effective dose equivalent, which is not presently approved by the staff for application to accident analyses. It.is presently approved only for use for 10 CFR Part 20 applications. Therefore, any future calculations of doses should be based upon the methodology in Regulatory Guide 1.3. The licensee's evaluation, which provide the basis for the proposed revisions, notes that two parameters of Hatch Unit 2 CRDA analysis are not bounded by 9309020292 930s17 - DR ADOCK 05000321 PDR ~
.~.- J l l . ) l l NEDO-31400 parameters. The unbounded parameters are the fraction of damaged fuel that melts, and the iodine washout /plateout fraction. The fraction of melted fuel assumed in the NED0-31400 report is less than that assumed in the CRDA analysis contained in the Hatch Final Safety Analysis r Report (FSAR). However, the number of fuel rods failed and the power level per rod assumed in the NED0-31400 report are sufficiently more conservative i than the Hatch FSAR values such that the non-conservatism in the fraction of j melted fuel is offset. 1 -( The fraction of iodine assumed to plate out in the NED0-31400 analysis is greater than the Hatch FSAR value by a factor of 5. Therefore, the fraction -{ of condenser activity that remains airborne is less in the NED0-31400 analysis than in the Hatch analysis. This non-conservatism, however, is offset by the higher condenser leak rate assumed (factor of 2) and a higher value of Chi /Q (factor of 8). i In addition to verification that input assumptions used in the CRDA analysis were applicable to a specific plant, the staff's SER on NED0-31400 also ) required the following: i 1. The licensee must provide reasonable assurance that increased levels of radioactivity in the main steam lines will be controlled expeditiously to limit both occupational doses and environmental releases; and, 2. The MSLRM and offgas radiation monitor alarm setpoint must be set at 1.5 times the nominal N-16 background dose rate at the monitor locations, and the licensee must promptly sample the reactor coolant to determine possible contamination levels if the setpoint of either j monitor is exceeded. The licensee. indicated that both annunciator response procedures (ARPs) and abnormal operating procedures (A0Ps) are entered upon receipt of MSLRM alarms l which are set at 1.5 times background including N-16. These procedures provide guidance for checking secondary containment conditions and notifying plant personnel. A0P 34AB-0PS-062, " Closure of MSIVs on High Radiation" will I be revised such that the entry condition is receipt of a high radiation alarm l rather than MSIV closure on high radiation. This procedure will include a requirement to sample the reactor coolant upon receipt of a high radiation l alarm. If area radiation monitor.s exceed specified levels, entry into the l secondary containment control'section of the emergency operating procedures is required. ' Radiological procedures are in place which provide guidance to l plant personnel for exiting high radiation areas upon indication of unexpectedly high area radiation monitor readings. Finally, offgas pretreatment monitors which alarm at 1.5 times background including N-16 will be monitored, by procedure, upon receipt of a high MSLRM alarm. Performance of a prompt effsite dose assessment is required through entry into a separate A0P. Based upon the incorporation of the above staff position, the staff concludes that. upon implementation of the revised. procedures described in the i
. licensee's submittal, the requirements of the staff's generic SER on NE00-31400 are satisfied for Hatch Units 1 and 2. The licensee's request also included elimination of the main steam line (MSL) drain valves from the isolation logic. Although not addressed specifically in the GE analysis, the request is considered to be insignificant because the exhaust from the drain path that discharges to the main condenser is minimal when compared to the MSIV's, and both paths are processed by the effgas system. This change is, therefore, acceptable. Furthermore, the licensee's request included the removal of the MSLRM high radiation trip from the main control room environmental (MCREC) system. This change was not addressed in the generic (NED0-31400) analysis. An important 1 function of the pressurization mode of the MCREC system is to protect the main control room operators during a design basis accident (DBA) such as CRDA. The staff considers this change acceptable, however, because the pressurization mode is also initiated at the main control room air intake on a high radiation i signal. Redundant air intake radiation monitors are provided which are not susceptible to a loss of function due to a single failure. Also, the abnormal operating procedure (AOP) will have instructions to manually activate the pressurization mode of the MCREC system if an MSL high radiation signal is confirmed. Moreover, the licensee requested deletion of a requirement for chemistry personnel to adjust the MSLRM alarm setpoint within the 24 hour period prior to the start of hydrogen injection when reactor power is greater than 20% of rated thermal power. This is acceptable because the consequences of CRDA are insignificant above 20% power and the existing requirement remains unchanged below 20X power. The proposed amendment would also require that within 72 hours after a reactor startup chemistry personnel must make final adjustments to trip setpoints. This provides a reasonable amount of time for establishment of a steady state background radiation level and adjustment of setpoints. In addition, the licensee's request proposed changes to an action statement concerning offgas post treatment monitors. The revision is due to the installation of new offgas post treatment radiation monitors. The new monitors do not have a "downscale" switch position. The new action statement will specify, without mention of a "downscale" switch position, that the I monitors should be tripped if one of the two monitors are inoperable. Since the existing statement which directs that the monitors be tripped in the "downscale" position is no longer applicable, the staff agrees that it should be replaced with the revised action statement. l The staff has reviewed the proposed TS changes for Hatch, Units 1 and 2, which I involve the elimination of the MSIV closure, the reactor scram, and the control room pressurization functions of the MSLRM. The request also included removal of the MSL drain valves from the isolation logic, revisions to the hydrogen water chemistry footnotes and an action statement concerning the of fgas post treatment monitors. i i l
t l 'l ] ' Based on above evaluation, the staff finds that the proposed TS revisions have no adverse impact on safety, and do not pose an undue risk to public health and safety, and are, therefore, acceptable.
3.0 STATE CONSULTATION
l In accordance with the Commission's regulations, the Georgia State official was notified of the proposed issuance of the amendments. The State official j had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
i The amendments change a requirement with respect to the installation or use of facility components located within the restricted area as defined in 10 CFR t I Part 20. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, i of any effluents that may be released offsite, and that there is no i 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 i public comment on such finding (58 FR 19482 dated April 14, 1993). 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 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 l public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulation.s, and (3) the issuance of the amendments will not be inimical to the common .j defense and security or to the health and safety of the public. Principal Contributors: A. Wilford J. Harold l K. Jabbour l Date: August 17, 1993 I t I l l .}}