ML20116M436
| ML20116M436 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 11/12/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20116M412 | List: |
| References | |
| NUDOCS 9211200269 | |
| Download: ML20116M436 (5) | |
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UNITED STATES i
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WASHINGTON, D C. 20fd6
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- f EAFElY LyALVAAILQLDY TH( OfflGE Of NQCLEAR REAC10R 31f#LAT10N Rf1Al[P_JO AM[EDMRLRQm140 T0 FACILJTY OPERATJRCG_LICH(SE NO. DPR-29 NIDEUiDMML!io.13510 fAChiTY 01 BATING LICH{Sfji0. DPR-30 LOMM0fNEA1J1LQljiON COMPANJ NiD LOWA-ILLR1015 GAS AND_fiff]T_RIC_ COMPANY QUAD _Cilli 5 NUELLAR POWER STALLOLLVR!151 AND_2 POCKET N0_S. 50-154 ANDJ 0-265 1.0 B[ULo[ LUC 110N By correspondence dated April 20, 1992, the Commonwealth Edison Company (Ceco, the licensee) submitted a request to implement two changes to the Quad Cities Station, Units 1 and 2, lechnical Specifications (TS).
The first change involves a request to correct a typographical error (" streamline" to
steamline") in TS 3.2.f.1 and in the appropriate Bases Section.
(Unit 2 only).
The correction is an administrative request only, and does not involve any significant hazards considerations per 10 CFR 50.92.
The second change request involves deleting the isolation function require-ments of the chlorine and sulfur dioxide analyzers from TS 3.2.f 2, and the corresponding chlorine and sulfur dioxide analyzer surveillance requirements from TS Table 4.2.1.
This change request includes implementing any appropriate changes to the TS Bases Section.
The licensee's basis for requesting the proposed TS change is that the chlorine and sulfur dioxide monitors (analyzers) have resulted in eight spurious isolations of their control room ventilation damoors during the period October 1986 - february 1992.
The immediate Notification paragraphs of 10 CFR 50.72 and the Licensee Event Report (LER) paragraphs of 10 CFR 50.73 require that "any event or condition that results in an automatic or manual isolation of an Engineered Safety feature (EST)" be reported within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> by Emergency Notification System (ENS) and within 30 days by LER.
The licensee contends that reoval of the chlorine and sulfur dioxide analyzer requirements would prevent spurious actuations of the control room ventilation system, a plant safety system, and would reduce the number of ENS and LER notifications to the NRC.
The licensee requests that the requirements for the chlorine and sulfur dioxide analyzers shou'Id, therefore, be allowed to be removed from the Quad
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. Cities, Units 1 and 2, 15.
In lieu of having TS for chlorine and sulfur dioxide analyzers, the licensee instead proposes to:
1.
Make agreements with the local emergency preparedness agencies to inform Ceco of any threatening chemical spill or accident.
2.
Perform a triennial survey of chlorine and sulfur dioxide shipping and storage patterns to verify that no significant changes have occurred which would af fect the analysis for control room habitability.
2.0 EVALVA11pQtj Regulatory Guide (RG) 1.78, " Assumptions for Evaluating the Habitability of a Hutlear Power riant Control Room During a Postulated Hazar60us Chemical Release," states that, in regard to control room habitability, "for each chemical considered, the values of importance are the human detection threshold," and the " toxicity limit" which is defireu as "the maximum concen-tration that can be tolerated for two minutes without physical incapacitation of an average human."
Regulatory Guide 1.78 recommends that licensee's have procedures and traini,19 which cover the use of protective breathing masks in the event of an onsite or offsite toxic release which could render the control room uninhabitable.
Accordingly, control room personnel should be capable of putting on respiratory equipment within two minutes of achieving the toxicity limit of the noxious gas.
This assumes that a constant concentration profile at the toxic limit level is maintained during the two minutes needed for the donning the respiratory equipment.
Regulatory Guide 1.78 also states, however, that shipments of hazardous chemicals do not need to be included in control room habitability studies if the route of transportation is not within five miles of the control room, or if the frequency ot 'Hpments is less than ten per year for truck traffic, less than 30 per year for rail traffic, and less than 'n per year for barge traffic.
The licensee has contracted an outside engineering firm to perform a study of chlorine and sulfur dioxide hazards created by the Soo and the Chicago and Northwest Railroads.
The Soo Railroad and the Chicago and Northwest Railroad are the only two means of transportation which ship chlorine and sulfur dioxide within 5 miles of the plant and in quantities in excess of those specified in RG 1.78.
No quantities of chlorine or sulfur dioxide are stored within the plant boundaries and no quantities of chlorine or sulfur dioxide have been documented as being shipped by barge or by truck within a five mile radius of the plant.
The Soo Railroad curves around the plant from the SSW to the NE, with its nearest proximity being approximately 1.75 miles west of the plant.
The Chicago and Northwestern Railroad is five miles north of the plant at its nearest point.
According to the contractor's evaluation, the Quad Cities control room would exceed chlorine or sulfur dioxide toxicity limits within two minutes of detection in the event of an offsite release of chlorine or sulfur dioxide within five mile radius of the plant.
This conclusion has been confirmed by Extran and Control Room Habitability computer codes (developed by the NRC for s
estimating toxic gas concentrations achieved in the control room during onsite or offsite chemical releases).
The acceptability of the licensee's TS amendment request, therefore, depends on the probabilistic approach set in Standard Review Plan (SRP) 2.2.3, " Evaluation of Potential Accidents."
According to SRP 2.2.3, offsite hazards which have the potential for causing onsite design basis events should have a low probability of occurrence.
This is acceptable if the probability of occurrence of a design basis event resulting from an offsite accident, and resulting in a release of radioactive exposure in excess of the requirements of 10 CFR 100, does not exceed the NRC probability objective of 1 x E-7 per year.
Since it is not always feasible to perform accurate calculations of accident / event probabilities, a probability on the order of 1 x E-6 may be acceptable if, when combined with qualitative arguments, the realistic probability of occurrence can be shown to be lower.
The contractor performed a probabilistic analysis to determine the probability of an offsite chlorine or sulfur dioxide release accident rendering uninhabitable conditions in the control room (accidents /yr).
The contractor's analysis is based upon a statistic that an offsite tank of chlorine or sulfur dioxide, of sufficient quantity.o cause a minimum of $5,000 in cumulative damages, would have a probability of 1.98 x E-8 of causing an accident (accidents / car / mile, as cited by a local state agency).
The analysis accounts for local meteorological and transportation factors.
This resulted in a calculated aggregate probability of 6.29 x E-7 (accidents / year) that a chlorine release accident, created either by the Soo Railroad or the Chicago and Northwestern Railroad, would cause the Ontrol room to be uninhabitable.
The aggregate probability of a sulfur dioxida accident rendering the control room uninhabitable was similarly calculated to be 1.28 x E-6 (accidents / year).
Since the aggregate probabilities were above the NRC's acceptance criteria of 1 x E-7, the contractor provided the following qualitative arguments to provide assurance that the aggregate probabilities are below an order of E-6 (accidents / year):
The contractor cited the U.S. Department of Transportation.
Federal Railroad Administration statistic that a'ratiroad-tank car of sufficient mass to cause a minimum $5,000 in cumulative damages has a 1.98 x E-8 probability of having an accidental. release.
A 90 ton railroad car has the capability of causing at least $5,000 in cumulative damages.
Since the mass of the car is greater than that which would cause a $5,000 cumulative damage, the probability of an offsite accident from a chlorine or sulfur dioxide tank car on the Soo or Chicago and Northwestern Railroads would be lower than 1.98 x E-8.
The. contracter's analysis was based on summer conditions.. Since chlorine and sulfur dioxide shipments occur year round, and since diffusion factors during the spring, fall, and winter months are normally lower than those during the summer, the probability of an
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offsite toxic release reaching the control room would be lower than that cited by the contractor.
The contractor's study considered all wind stability classes which could render the control room uhinhabitable.
The worst case wind speed was determined to be approximately 2.2 meters per second.
The wind speeds which can render the control room uninhabitable, however, occur only a small portion of the time.
Therefore, the probability of the control room becoming uninhabitable would be lower than that cited by the contractor.
These qualitative arguments seem to be based on reasonable assumptions.
The contractor's analysis, therefore, provides a reasonable assurance that the probability of rendering the control room uninhabitable, as created by an offsite chlorine or sulfur dioxide release, would be lower than the value of 1 x E-6, as cited in SRP 2.2.3.
The low probability excludes offsite chlorine and sulfur dioxide accidents from being classified as design basis events and, therefore, provides a basis that removal of the chlorine and u.] fur dioxide detectors would not present a significant hazards consideration as defined in 10 CFR 50.92.
Supplemental information provided by the licensee indicates that the licensee currently has procedures and training implemented which instruct licensed and non-licensed operators in the operation of respiratory equipment. -Based on the licensee's evaluation and commitments presented in its amendment-submittal, the staff finds acceptable the removal of the chlorine and ' sulfur dioxide requirements from the Quad Cities, Unit 1 and 2, TS as described in the amendment submittal.
The administrative change request (i.e., correct
" streamline" to "steamline") for the Quad Cities 2 TS is also approved.
By letter dated November 6, 1992, the licensee proposed three minor changes to the Bases:
(1) the May 1988 date for the Sargent and Lundy report should be April 1991, (2) the clause "and the chlorine and sulphur dioxide detectors were deleted from the plant" should be "to delete the chlorine and sulphur dioxide detectors from the plant," and (3) the reference to SAR Section 6.2.6.3 should be VFSAR Section 7.3.1.4.
These three changes are also approved.
3.0 STATE CONSULTATION
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.
4.0
[NVIRONMENTAL CONSIDERATION The amendments change 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 and change surveillance requirements.
The NRC staff hes determined that the amendments involve no significant increase in the amounts, and no
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5-l significant change in the types, of any effluents that may be released l
of fsite, and that there is no significant increase in individual or cumulative l
occupational radiation exposure.
The Commission (> >; previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public connent on such finding (57 FR 37562). 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), nn environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
5.0 (0Ntly11QN 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: J. Medoff Date:
November 12, 1992