ML20080N470
| ML20080N470 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 02/28/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20080N468 | List: |
| References | |
| NUDOCS 9503060300 | |
| Download: ML20080N470 (4) | |
Text
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WASHINGTON, D.C. 20065-0001 i
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 60 TO FACILITY OPERATING LICENSE NO. NPF-72 AND AMENDMENT NO. 60 TO FACILITY OPERATING LICENSE NO. NPF-77 COMMONWEALTH EDIS0N COMPANY BRAIDWOOD STATION. UNIT NOS. 1 AND 2 DOCKET NOS. STN 50-4$6 AND STN 50-457
1.0 INTRODUCTION
By letter dated January 5,1994, Commonwealth Edison Company (Comed, the licensee) proposed changes to the Braidwood Station, Unit Nos. I and 2, Technical Specifications (TS), Section 4.7.6.e.6., which would remove a surveillance requirement to verify, every 18 months, that the control room ventilation system can be isolated manually and placed in the recirculation mode of operation. The operators would initiate this manual isolation in response to a report of a chlorine release in the vicinity of the Braidwood Station. The licensee also requested to remove a commitment to demonstrate control room integrity on a periodic basis.
By letter dated April 26, 1994, Comed provided a revised evaluation of significant hazards considerations.
By letter dated September 30, 1994, the licensee committed to perform periodic surveys in the Braidwood Station's vicinity to ensure that any new chlorine transportation, storage and production would not introduce a new risk to the control room personnel.
By letter dated January 12, 1995, the licensee incorporated the commitment to survey the Braidwood Station area for new sources of chlorine in the evaluation of significant hazards considerations.
2.0 BACKGROUND
By letter dated June 3,1986, the licensee provided an analysis to demonstrate that the chlorine monitors for the control room intake were not required. The licensee's analysis involved a survey of the offsite sources of chlorine within five miles of the station, a calculation of the toxic gas and infiltration, and a probability of the rupture of a chlorine tank car on the Norfolk and Western Railroad.
By letter dated March 4, 1987, the NRC staff approved the licensee's proposal to remove the chlorine detectors from the control room ventilation system.
In its safety evaluation, the NRC staff required the licensee to demonstrate that the control room ventilation could be isolated, and required the licensee to demonstrate annually the control room integrity as it relates to the chlorine intrusion concern.
By letter dated May 6, 1987, the licensee submitted a request to include a TS surveillance to verify that the control room ventilation can be placed in
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recirculation mode manually and committed to demonstrate control room integrity. The licensee's commitment and TS surveillance were approved with the issuance of NUREG-1002, Supplement 3, " Safety Evaluation Report" dated May 1987.
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3.0 EVALUATION l
l By letter dated January 5,1994, the licensee provided a new evaluation and survey to demonstrate that the chlorine hazard to the control room had become practically zero. This analysis was initiated because the Norfolk and Western Railroad tracks near the vicinity of Braidwood Station were removed, thereby reducing the potential for a chlorine spill. The 1986 analysis and subsequent requirement to demonstrate control room ventilation integrity were based on the fact that chlorine was transported on the railroad tracks.
The 1994 analysis was completed by Sargent and Lundy engineers to evaluate the effects of a postulated offsite chlorine release on control room habitability and was conducted in two parts. The first part consisted of calculating the minimum distance from the control room intake as a function of chlorine spillage.
This calculation determined that, for a one ton spillage quantity, the minimum distance from the control room intake to meet the Regulatory Guide 1.95 limit of 15 parts per million, is 4900 feet. The calculation also determined the minimum acceptable distance for a stationary 90 ton spillage to be 6.4 miles.
The second part of analysis consisted of conducting a survey of stationary users of chlorine and transported shipments of chlorine.
Sargent and Lundy conducted the stationary chlorine users survey within the 10 mile radius of the station, because it would envelope the critical radius of 6.4 miles for the largest container size, which is 90 tons. The results of the survey showed that there were no stationary users within ten miles that would pose a toxic threat to the control room personnel. Sargent and Lundy then conducted a transported chlorine survey within a 10 mile radius of the Braidwood Station.
The survey indicated that there were no railroads within this radius that could transport chlorine and the largest shipment by truck would be one ton.
The analysis determined the probability of an accidental release from a truck on State Route 53 or 129, which are near Braidwood 4
Station, to be 2.0 x 10 The probability that when the concentration of chlorine in the control room reaches toxic limit, it will incapacitate the l
operators and cause a core damaging accident resulting in fission products release in excess of 10 CFR, chlorinereleaseof2.0x10' fart 100isbelow0.1. With the probability of
, the overall probability of such an event is, l
therefore, within the acceptable limits of NUREG-0800, SRP 2.2.3.11.
The i
licensee's analysis concluded that because of low probability of release from a transported chlorine source and no potential for stationary chlorine release that could pose a threat to control room habitability, the commitment to demonstrate annually the control room ventilation integrity as it relates to l
the chlorine intrusion concern and the surveillance requirement, TS l
Section 4.7.6.e.6., to demonstrate manual isolation of control room l
ventilation can be removed.
In addition to the above analysis, the licensee has committed to perform a chlorine survey every 3 years and to perform associated evaluations to ensure that the risk to the control room personnel from any potential chlorine accident is maintained sufficiently small. Additionally, the licensee is committed to document the results in its annual reports.
In case the licensee becomes aware of a potential chlorine hazard, either through the survey or i
other means, the licensee should take appropriate actions to minimize the risk i
to the control room personnel and inform the NRC in writing (including a i
reference to this safety evaluation).
Finally, the licensee will continue to meet the requirements of NRC's March 4,1987, Safety Evaluation Report by j
maintaining a notification communications with Will County, in the event of 1
chlorine accident, and by maintaining the requirement to isolate the control room, in case of a chlorine release accident.
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The staff concludes that the licensee's removal of the commitment to t
demonstrate annually the control room ventilation integrity as it relates to chlorine intrusion concern and surveillance requirement, TS Section 4.7.6.e.6., to demonstrate manual isolation of control room ventilation meet the relevant requirements of 10 CFR Part 100.
This conclusion is based on the following. The licensee's analyses have identified potential accidents related to the presence of hazardous material or i
activities in the site vicinity which could affect the plant and from these the licensee has demonstrated that the plant is adequately protected and can be operated with an acceptable degree of safety with regard to these potential accidents.
In addition, the removal of the railroad tracks from the vicinity of Braidwood have reduced the probability of the chlorine release.
- Finally, the licensee's commitment to periodically survey the Braidwood vicinity for potential new sources of chlorine will provide assurance that no new toxic threats to the control room habitability will go unnoticed.
Based on the lower probability of a chlorine release accident, the licensee's commitment to maintain notification communication with Will County, the requirement to 1
isolate the control room ventilation in case of a reported chlorine release, a chlorine survey every three years and the retention of the surveillance
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requirement in the station's TS to periodically verify (at least once every 18 i
months) the control room ventilation system's capability to pressurize the control room, the staff has determined that the removal of the commitment to I
demonstrate annually the control room ventilation integrity as it relates to i
chlorine intrusion concern and removal of control room ventilation manual isolation surveillance is consistent with the guidance of SRP Section 6.4 and is, therefore, acceptable.
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4.0 STATE CONSULTATION
i In accordance with the Commission's regulations, the Illinois State official was notified of the proposed issuance of the amendments. The State official had no comments.
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5.0 ENVIRONMENTAL CONSIDERATION
The amendments change a surveillance requirement. 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 (60 FR 4930). 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.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the 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 Contributor:
R. Assa Date: February 28, 1995 i