ML20082T450
| ML20082T450 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 09/05/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20082T448 | List: |
| References | |
| NUDOCS 9109180248 | |
| Download: ML20082T450 (3) | |
Text
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i NUCLEAR REGULATORY COMMISSION
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WASHINGTON. D.C. 20065 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 60 TO FACILITY OPERATING LICENSE NO. NPF-47 GULF STATES UTILITIES COMPANY RIVER BEND STATION, UNIT 1 DOCKET NO. 50-458
1.0 INTRODUCTION
By letter dated May 14, 1991, Gulf States Utilities Company (GSU) (the licensee) requested an amendment to Facility Operating Li:ense No. NPF-47 for the River Bend Station, Unit 1.
The proposed amendment would change the alarm setpoint for the offgas pretreatment noble gas activity monitor in Technical Specification (TS) Table 3.3.7.1-1, " Radiation Monitoring Instrumentation,"
from the current value of 2.4e x 104 millirem / hour (mr/hr) to 3410 mr/hr.
The original setpoint was discovered to be non-conservative due to calculation methodologies and resulted in a condition outside the design basis of the plant.
The offgas system receives offgas from the main condenser air ejectors and S dGigned to reduce the gaseous radwaste emissions from the plant and to alert the operators of fuel failure by monitoring radioactivity in the condenser offgas before it enters the delay pipe and after it has passed through the offgas condenser and water separator.
The system consists of heaters, catalytic recombiners, condensers, water and moisture separators, filters, and charcoal adsorbers.
The noble gas activity radiation monitor located af ter the of fgas condenser concinuously monitors radioactivity releases from the reactor and monitors activity going into the charcoal adsorbers and provides an alarm in the control room on high radiation.
The system is normally in the bypass mode during startup testing to protect the charcoal adsorbers when the gas activity is zero or very low.
2.0 EVALUATION The non conservative calculations were discovered in March 1990, during a review for a modification to the location of the dettctor portion of the monitor.
Licensee Event Report (LER)90-005, Revision 0, dated April 2, 1990, was submitted and descr.oed the identification of the condition.
A review of the methodology for establishing the original setpoint identified two errors.
First, the original calculation did not consider the different flow rates in each operating mode (start-up versus power operation).
The current analysis bases the setpoint only on the flow rate during power operation.
Second, the original calculation used 105 percent reactor thermal power as the basis for the total steam-to-main condenser mass flow rate.
The current analysis bases the setpoint on 100 percent reactor thermal power which is consistent with the Technical Specification total activity release rate limit.
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j j i The new setpoint is based on operational experience which confirmed that during plant startup, 95 percent of the non-enndensable gases are removed from the main condenser by the air removal system compressors which are filtered and released through the plant stack.
This occurs with the offgas system not in operation and the charcoal adsorbers bypassed to avoid damage to the adsorbers due to high moisture content in the offgas.
Once the air removal compressors are shut off and the offgas system flow is less than j
50 scfm, the charcoal adsorbers are taken out of the bypass mode and the j
offgas system is placed in service.
This supports the offgas flow rate used to calculate an alarm setpoint of 3410 mr/hr, The main steam and condenser offgas are monitored in several areas in addition to the offgas pretreatment monitor, These include the main steam tunnel, offgas downstream of the charcoal adsorber, the main plant exhaust, and the offgas building ventilation system, Due to these redundant, independent monitors and alarms, G5U is assured that the non-conservative setpoint has
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not affected the health and safety of the public.
Additionally, G50 plans on incorporating the new calculations into the Updated Safety Analysis Report, Section 13,3, " Emergency Plan," by updating i
the emergency action level 3, Notice of Unusual Event, and action level 1, t
Alert, notifications.
I 1he NRC staff has reviewed the LERs, the T5 change request, and Sections 9.4.4.2.5, 11.3.2, and 15,7 of the Updated Safety Analysis Report, and 11.3 l
of the Standard Review Plan, and concludes the proposed decrease in the pretreatment radiation monitor alarm setpoint to 3410 mr/hr is acceptable, j
3.0 STATE CONSULTATION
I In accordance with the Commission's regulations, the Louisiana State official was notified of the proposed issuance of the amendment.
The State official had no comments, t
4.0 ENVIRONMENTAL CONSIDERATION
i The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in i
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 l
no significant hazards consideration, and there has been no public comment
- on such finding (56 FR 27046).
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, j
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
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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:
Claudia M. Abbate, PDIV-2 f
Donna M. Skay, PDIV-2 Date:
September 5, 1991 b
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