ML20012B832
| ML20012B832 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 03/02/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20012B830 | List: |
| References | |
| NUDOCS 9003160390 | |
| Download: ML20012B832 (4) | |
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SAFETY EVALUATION BY.THE OFFICE OF WUCLEAR REACTOR. REGULATION RELATED T0. AMENDMENT NO. 47 l
TO FACILITY OPERATING LICENSE NO..WPF-49 l
NORTHEAST NUCLEAR. ENERGY COMPANY. ET.AL.
MILLSTONE NUCLEAR POWER STAT 10N.. UNIT.NO. 3 i
DOCKET.N0. 50 423 INTRODUCTION By applications for license amendment dated November 2 and December 1,1989, Northeast Nuclear Energy Company, et al. (the licensee), requested changes to Millstone Unit 3 Technical Specifications (TS).
The proposed amendment would modify TS 3.6.4.1, " Hydrogen Monitors," and TS 3.3.3.6, " Accident Monitoring instrumentation," to eliminate inconsistencies concerning Limiting Conditions for Operations (LCOs) associated with hydrogen monitors. The proposed amendment would also modify 4.6.4.2b.4, " Electric i
Hydrogen Recombiners," to provide variable acceptable criteria for flow testing.
DISCUSSION AND. EVALUATION The operability of the combustible gas control equipment required for the detection and control of hydrogen gas ensures that this equipment will be available to maintain the hydrogen concentration within containment below its 3
flammable limit during post-loss-of-coolant-accident (LOCA) conditions. The hydrogen monitors provide information used to determine the need to start the hydrogen recombiners or initiate containment purge. At the present time.
TS 3.6.4 and TS 3.3.3.6 contain conflicting requirements concerning remedial actions to be taken when one or more hydrogen monitors become inoperable, as i
follows:
TS 3.3.3.6 allows reactor operation up to 7 days with one hydrogen monitor inoperable and up to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> with two hydrogen monitors inoperable.
If
-the inoperable monitors cannot be returned to service, the plant must be i
in Hot Standby in 6' hours and Hot Shutdown within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
Operability of the hydrogen monitors is required in Modes 1, 2 and 3.
Startup of the facility with inoperable hydrogen monitors is permitted (the provisions of TS 3.0.4 are not applicable.)
TS 3.6.4.1 allows reactor tperation up to 30 days with one hydrogen L
-monitor inoperable and up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> with two hydrogen monitors inoperable.
If the inoperable monitors cannot be returned to service, the plant must be in Hot Standby within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Operability of the hydrogen monitors is required in Modes 1 and 2.
Startup of the facility with inoperable hydrogen monitors is not permitted (the provisions of TS3.0.4areapplicable.)
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'l The licensee has proposed that TS 3.6.4.1 and TS 3.3.3.6 be modified to eliminate the conflicting requirements concerning inoperable hydrogen monitors.
The requirements of TS 3.3.3.6 would be changed to increase the allowable out-of-service time from 7 days to 30 days for one hydrogen monitor and from 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for inoperability of two hydrogen monitors. The above changes to TS 3.3.3.6 would provide consistency with the requirements of TS 3.6.4.1.
The proposed change to TS 3.3.3.6 also includes a reformatting of the associated Action Statements to segregate the LCOs for the hydrogen monitor.
The requirements of TS 3.6.4.1 would be changed as follows to provide consistency with TS 3.3.3.6:
Increase the range of applicable modes from Modes 1 and 2 to Modes 1, 2 and 3.
A statement would be added that the provisions of TS 3.0.4 are not applicable.
The remedial action required for the inoperability of one or more hydrogen monitors, in the event that the monitors cannot be restored would be extended from "...at least Hot Standby within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />" to also include "...and in at least Hot Shutdown within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />."
On November 1, 1983, the NRC staff issued Generic Letter (GL) 83-37, " Technical Specifications." The purpose of GL 83-77 was to provide guidance to licensees on modifications of TS to address a number of Post-THI concerns including the operability of hydrogen monitors.
In this regard, the licensee's proposed changes to TS 3.3.3.6 and 3.6.4.1 are in substantial conformance with NRC staff guidance on operability of hydrogen monitors and are thus, acceptable.
With regard to the hydrogen recombiner system, this system is designed to maintain the hydrogen concentration in the containment below 4 volume percent following a LOCA. To ensure operability of the system in the event of a single f ailure of any component, the system is arranged in two redundant 100 percent capacity trains. The parameters presented in Regulatory Guide 1.7 are used in the analysis of hydrogen generation following a DBA. The analysis of hydrogen generation following a LOCA and the capability of the hydrogen recombiners or the backup purge system, to maintain a hydrogen concentration below 4 percent volume is described in the Millstone Unit No. 3 Final Safety Analysis Report (FSAR) Section 6.2.5.
Technical Specification 4.6.4.2b.4 requires that the licensee verify, every 18 months, that the hydrogen recombiners demonstrate a flow rate of at least 40 scfm. Although hydrogen recombiner flow rate is a function of containment pressure, the existing TS 4.6.4.2b.4 does not specify a containment pressure for performance of the hydrogen recombiner flow test.
During a recent review of hydrogen recombiner surveillance test data and the original calculation for post LOCA hydrogen generation inside containment, the licensee identified an inconsistency. Specifically, the original analysis assumed that S0 scfm of containment air would flow thorough the system while the containment pressure was at 9 psia in post-LOCA conditions. This assumed
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3-flow rate is also greater than tested flow rates which have been as low as 42 sefm when containment is between g and 10 psia. Therefore, the licensee performed a new calculation and determined the minimum acceptable flow rate through hydrogen recombiners to be 40.5 scfm. This flow rate will still ensure containment hydrogen concentration remains below 4 volume percent during the accident if the hydrogen recombiners are started within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of a DBA when the hydrogen concentration of the containment atmosphere is at or below 1.8 volume percent. As stated in FSAR Section 6.2.5, the hydrogen recombiners would be started well before 1.8 volume percent hydrogen is detected in the containment.
The proposed change to TS 4.6.4.2b.4 would replace the 50 scfm acceptance criteria for the hydrogen recombiner flow test with an acceptance criteria that is a function of containment pressure. The proposed variable acceptance criteria range almost linearly from approximately 40 scfm at a containment pressure of 8.5 psia to approximately 80 scfm at a containment pressure of 15.5 psia. The lowest flow acceptance criterion, however, would be limited to approxinately 51 scfm since the lowest containment pressure is limited to 10.6 psia by TS 3.6.4.1 as indicated in the licensee's letter dated January 19, 1990.
The proposed change to TS 4.5.4.2b.4 provides acceptance criteria for hydrogen recombiner testing which are adequate to demonstrate that the recombiners will perform their post-LOCA design function. 140reover, the acceptance criteria provide the flexibility to allow the licensee to test the recombiners over a range of containment pressures. Accordingly, the proposed change to TS 4.6.4.2b.4 is acceptable.
ENVIRONMENTAL CONSIDERATION This amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. We have 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 staff has previously published a proposed finding that the amendment involves no significant hazards consideration and there has been no public comment on such finding. 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 assessnent need be prepared in connection with the issuance of the amendment.
CCNCLUSION We have 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, and (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.
Dated:
March 2, 1990 Principal Contributor: D. Jaffe d
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' DATED:
March 2, 1990' AMENDMENT NO. 47 TO FACILITY OFT iATING LICENSE NO. NPF-49 i
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