ML20248G341
| ML20248G341 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 03/31/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20248G337 | List: |
| References | |
| NUDOCS 8904130394 | |
| Download: ML20248G341 (5) | |
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UNITED STATES l
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' NUCLEAR REGULATORY COMMISSION
- y-WASHINGTON, D. C. 20655
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l SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.
19 TO FACILITY OPERATING LICENSE NO. NPF-58 l
l THE CLEVELAND ELECTRIC ILLUMINATING COMPANY, ET AL.
l PERRY NUCLEAR POWER PLANT. UNIT NO. 1 l
DOCKET N0. 50-440
1.0 INTRODUCTION
l By letter dated December 29, 1988, the Cleveland Electric Illuminating Company (CEI), the licensee'for Perry Nuclear Power Plant, Unit 1, proposed changes to plant technical specifications (TS) to revise the Primary Containment Integrity requirements during fuel handling. The proposed changes are requested to allow opening of one or two 3/4-inch vent and drain lines for Type C locel leak rate I
testing (LLRT) of up to two penetrations during refueling activities. These changes were proposed to reduce the refueling outage duration, while still maintaining control to reestablish containment integrity.
l The current Perry TS 3/4.6.1, requires the suspension of handling irradiated fuel in the primary containment if its integrity is not maintained. As a result, most Type C local leak rate surveillance testing required by 10 CFR Part 50, Appendix J, cannot be performed while refueling is in progress.
The licensee has performed an evaluation to show that opening of up to 50 3/4-inch vent and drain line pathways with a resulting flow of 100 CFM assuming 0.25-inch water gauge differential between the primary containment and the auxiliary building would not result in unacceptable offsite doses in the event of a fuel handling accident. Also, at no time during the testing process will the containment isolatinn valves be disabled. Therefore, the co'ntainment isolation function provided by the valves could be available if called upon to perform their isolation function.
2.0 EVALUATION The staff has performed independent calculations whicii confirmed the licensee's l
calculated flow rate of 100 CFM based on 50 3/4-inch vent and drain line pathways open at an expected 0.25-inch water differential pressure between the primary containment and the auxiliary building. Although a pressure producing transient during refueling is not expected, the maximum containment pressure limited by plant TS Section 3.6.1.6 is less than 1 PSID between the primary 1
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, containment and the auxiliary building. At 1 PSID, opening of four 3/4-inch vent and drain lines would result in a flow rate of 84 CFM.
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The staff has reviewed the licensee's offsite dose rate calculations and concluded that the calculated offsite doses based on a 100 CFM flow rate through the vent and drain paths are acceptable assuming 15 days of decay time.
l This analysis is only valid for the first refueling. Eech penetration into the t
primary containment is typically provided with vent and drain valves to facilitate Type C leak rate test for the inboard and outboard containment isolation valves.
In the Perry Safety Evaluation Report (NUREG-0887) dated May 1982, the staff l
previously evaluated a postulated fuel handling accident using assumptions contained in Positions C.1.a through C.1.k of Regulatory Guide 1.25 and the proceduresspecifiedinStandardReviewPlan(SRP)Section15.7.4(NUREG-0800).
l In addition, the specified assumptions postulate a single dropped fuel assembly, the kinetic energy of which is expended with perfect mechanical efficiency in breaking open the maximum possible nunber of fuel rods.
Instantaneous release of noble gases and radiciodine vapor from the gaps of the broken rods occurs as gas bubbles pass up through the water covering the fuel.
All radioactivity reaching the primary containment atmsphere is exhausted within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
l In evaluating the proposed amendment, the staff performed the independent J
offsite dose calculations using the same assumptions previously used (includingatmosphericdiffusionparameters)forapostulatedfuelhandling j
accident at Perry with the following four exceptions:
(1) A decay period of 15 days was assumed (from February 22, 1989 to March 9,
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1989).
(2) An unmitigated release of 100-cubic-feet per minute (CFM) occurred during the entire 30 days from the primary containment through up to two open vent and drain lines in addition to the maximum allowable unidentified primary containment leakage of 0.2 percent per day, The licensee stated in their proposal that the leak rate test procedure (Type C test) typically involves the following:
(a) Draining and refilling of the liquid from the test volume (betweeninboardandoutboardmanualisolationvalves). Each of these operations will take less than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> on the average.
During these drainings and refilling operations, a water seal will exist which would prevent (due to the lack of differential pressure) release of airborne radioactivity from the primary containment.
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. (b) Connection and disconnection of test apparatus to and from the vent valves. The potential for airborne radioactivity releases from the primary containment does exist through a vent valve, a drain valve, and two inboard and outboard containment isolation valves during the time intervals between (1)completionoftestvolumedrainandconnectionoftest apparatus,- and (ii) disconnection of test apparatus and start l
of refill. At no time during the entire testing process are any
.open containment isolation valves disabled. Therefore, the q
containment isolation function provided by these valves would remain available if called upon to perform their isolation function. The plant operators would also be able to close any open automatic containment isolation valve from the main control room.
(c) Leak rate testing. The leak rate test itself will take less than 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> on the average. No airborne radioactivity release path-
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ways exist during actual' leak rate testing.
(3) No credit is given for mixing of airborne radioactive material with primary containment atmosphere prior to release to.the environment for the 1
entire 30-day period after the accident. The staff assumed that the only air exhausted from the containment is the air directly above the pool (24 j
inches).
The licensee stated in the proposal that they conservatively assumed i
isolation of the Containment Vessel and Drywell Purge Systems (CVDPS's) to occur within 20 seconds after the accident. This isolation time includes the travel tinu of radioactive materials to the radiation monitor, receipt of isolation signal by the isolation damper, and the closing time of the damper (the current Perry Technical Specifications require the maximum damper closure time of 4 seconds in Table 3.6.4-1).
The staff assumed the CVDPS is in operation at the time of the accident at the design flow rate capacity of 10,000 CFM. Therefore, approximately 3,300 cubic feet of contaminated containment air is released during the first 20-second period after the accident. No filtration credit (removal efficiency) was given for the CVDPS for containment air that was released before containment isolation occurs, since the CVDP is not an engineered safety feature (ESF) system.
(4) After 20 seconds from the time of a postulated fuel handling accident, i
throughout the entire 30-day period, there will be two release pathways remaining from the primary containment to the environment; (1) unmitigated release of 100 CFM through up to two open vent and drain lines and (ii) the i
4-maximum allowable unidentified primary containment leakage of 0.2 percent per day.
The Perry primary containment is a Mark III Pressure suppression containment with a free standing 6 steel structure with a total free air volume of approximately 1.2 x 10 feet. The refueling floor is at elevation 682' and most of the penetrations subject to Type C local leak rate testing are located between elevations 599' and 666'. Therefore, in the event of a fuel handling accident, airborne radioactive material ~would have to travel a minimum of 16 feet downward ;hrough refueling floor open areas to reach the first possible open )enetration to escape into the auxiliary or fuel building. However, tie staff conservatively assumed that the 100 CFM air exhausted from the containment is the air directly above the pool (96' x 36' x 2') throughout the entire 30-day period.
Any unidentified leakage from the primary containment into the annulus building (0.2 percent per day) is collected and processed by the annulus exhaust gas treatment system (AEGTS). The AEGTS is a redundant engineered safety features system.
Each AEGTS unit has a design capacity of 2,000 CFM and includes, among other things, one 4-inch deep carbon absorber and two high efficiency particulate air filters. The staff assumed 99 percent iodine removal efficiency by this ESF system. The staff finds that the offsite dose contribution from this pathway is negligible compared to that from the 100 CFM leakage pathway.
The offsite doses computed for the Exclusion Area Boundary (EAB)andLowPopulationZone(LPZ) boundary using the above four assumptions, assumptions contained in Regulatory Guide 1.25, and the procedures specified in SRP Section 15.7.4, are within the dose reference values of 10 CFR Part 100.
The dose reference values of 10 CFR Part 100 are 300 rem to the thyroid and 25 rem to the whole body at EAB and LPZ. SRP Plan Section 15.7.4 provides additional guidance by defining "well within" as 25 percent of the 10 CFR Part 100 dose reference values or 75 rem to the thyroid and 6 rem to the l
whole body at EAB and LPZ. The doses calculated were 23 rem to the thyroid and less than I rem to the whole body at EAB and 3 rem to the thyroid and less than 1 rem to the whole body at LPZ. The staff, therefore, finds that the proposed Perry Unit 1 TS changes are accept-i able on an interim basis for the first refueling only.
The flow from the containment through the open vent and drain pathways would occur only if the inboard containment isolation valve is open. When utilizing the proposed change, at no time during the testing process are i
the containment isolation valves disabled and, therefore. the containment i
isolation function provided by the valves would remain available if called l
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.5-upon to close. Additionally, administrative controls will ensure that the number of 3/4-inch vent and drainline pathways opened at any one time will be limited to two, control room operators will be aware of the openings, I
pressure differential will be monitored, and test engineers will make reasonable attempts to isolate vent / drain lines prior to evacuating if evacuation is announced over the PA system. These administrative controls will ensure that timely action will be taken to close open vent and drain valves and the isolation valves in the event of a fuel handling accident.
l The staff has determined, based on the operability of the containment isolation valves during the testing phase, administrative controls, the size of ver,t and drain valves and the low offsite dose consequences based on a 15-day decay period, that the proposed changes to Perry Technical Specifications concerning the primary containment integrity shutdown during fuel handling is acceptable on an interim basis for the first refueling only.
Final acceptance is contingent upon a favorable finding by the staff of the analysis without reliance on the 15-day decay time.
3.0 ENVIRONMENTAL CONSIDERATION
Pursuant to 10 CFR 51.21, 51.32, and 51.35 an environmental assessnent and finding of no significant impact has been prepared and published in the Federal Register on March 22, 1989 (54 FR 11830). Accordingly, based upon the environmental assessment, the Commission has determined that the issuance of this amendment will not have a significant effect on the quality of the human environment.
4.0 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, and (2) such activities will be conducted in compliance with the Commission's regulations and the I
issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors:
R. Goel J. Lee l
Dated:
March 31, 1989 I
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