ML20072K529
| ML20072K529 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 08/25/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20072K524 | List: |
| References | |
| NUDOCS 9408300138 | |
| Download: ML20072K529 (3) | |
Text
,.
E
'* ' E UNITED STATES 3#
NUCLEAR REGULATORY COMMISSION k..... j#
WASHINGTON, D C. 2055fMWJ01 l
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 89 TO FACILITY OPERATING LICENSE NO. DPR-22 NORTHERN STATES POWER COMPANY i
MONTICELLO NUCLEAR GENERATING PLANT DOCKET NO. 50-263
(
l.0 INTRODUCTION By letters dated November 30, 1993 and June 30 1994, Northern States Power Company (the licensee) submitted a request for amending Technical Specifications (TS) by deleting the requirements for a chlorine detection system in the following sections of TS: 3.2.1 (Instruments for Control Room Habitability Protection), 3.17.A and 4.17.A (Control Room Ventilation System),
Tables 3.2.9 (Instrumentation for Control Room Habitability Protection) and 4.2.1 (Minimum Test and Calibration Frequency for Core Cooling, Rod Block and Isolation Instrumentation) and Technical Bases for TS 3.2 (discussion of onsite and offsite toxic chemical hazards), and TS 3.17.A (discussion of control room ventilation).
The June 30, 1994, letter only provided documents cited in the amendment application and did not affect the staff's initial no significant hazards determination.
The licensee found that no chlorine is stored on the plant site, and the quantity of chlorine transported within a five mile distance from the plant is either too small to exceed safe concentrations in the control room after its accidental release, or the probability of an accident is below the limit for which the Standard Review Plan (SRP) requires safety analysis to be performed.
Based on this finding, the licensee concluded that the chlorine that is either stored or transported in the vicinity of the plant does not pose a safety hazard to the habitability of the control room, and there is no need for having chlorine detection capability at the plant.
2.0 EVALUATION Chlorine is no longer stored at the plant site. However, it is stored within a five mile radius from the plant in four facilities and is being transported by nearby rail and truck. The quantity of chlorine transported by rail exceeds the Regulatory Guide 1.78 criterion of 30 shipments per year and, therefore, the licensee evaluated the consequences of a postulated accident.
Chlorine is transported within a five mile radius from the plant by the Burlington Northern railroad with its line passing the plant on the opposite side of the Mississippi River with a point of closest approach of two miles.
i The maximum shipping load was found to be about 90 tons. The licensee has i
l l
9408300138 940825 i
PDR ADOCK 05000263 P
performed an analysis using conservative assumptions for wind direction, atmospheric dispersion conditions, and taking no credit for intervening structures or topology which would dilute concentration at the control room intake, an elevated control room intake, and spill absorption or dilution in surrounding ground or water.
The results of this analysis have indicated that accidental release of chlorine transported by the Burlington Northern railroad will not produce toxic concentrations in the control room for at least two minutes from its detection, giving enough time for the operators to don their protective equipment. The licensee's analysis has been reviewed by the staff and found to be acceptable.
Since the amount of chlorine released and the distance from the plant, used in the analysis of a railroad accident, were higher than in any of the chlorine i
storage facilities, this analysis constituted a bounding case and no analyses for the individual storage facilities had to be performed.
Chlorine is transported by the trucks in significant quantities on two main highways: Interstate 94, passing one-half mile from the plant, and Highway 10 passing approximately two miles from the plant.
Due to lack of information on the types and quantities of chlorine transported by trucks on these highways, the licensee has performed a probabilistic study to assess the likelihood of the accidents which would cause an unacceptable concentration of chlorine in the control room.
The study was performed using information on the volume of i
i the traffic carrying hazardous chemicals and the probability of their accidental release. From this study, the probability of toxic gas concentrations leading to incapacitation of the control room operator was determined.
Combining it with the probability of core damage due to unattended plant operation, the probability of the corresponding radioactive release and occurrence of potential exposures in excess of the 10 CFR Part 100 guidelines was determined to be 3.78x10'8 per year.
This is significantly lower than 10~7 per year which is the acceptable limit specified in the Standard Review Plan. The staff has verified the assumptions used by the licensee in its analysis and found them to be conservative.
The staff has reviewed the licensee's request for deletion of the chlorine detection system.
Based on the results of the review of the licensee's analysis and its probabilistic assessment, the staff concludes that the request is acceptable and deletion of the chlorine detection system would not cause unacceptable safety concerns.
3.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Minnesota State official was notified of the proposed issuance of the amendments.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendment changes 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.
The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any a
J.
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 no significant hazards consideration and there has been no public comment on such finding (59 FR 10010). 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.
5.0 CONCLUSION
The staff 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 amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
K. Parczewski Date:
August 25, 1994 i