ML20141A840
| ML20141A840 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 05/09/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20141A816 | List: |
| References | |
| NUDOCS 9705150027 | |
| Download: ML20141A840 (4) | |
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UNITED STATES -
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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 30eeM001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION g
RELATED TO AMENDMENT NO.185 TO FACILITY OPERATING LICENSE NO. DPR-71
.i CENSE NO. DPR-62 1
CAROLINA POWER & LIGHT COMPANY 2
BRUNSWICK STEAM ELECTRIC PLANT. UNITS 1 AND 2 DOCKET NOS; 50-325 AND 50-324
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1.0 INTRODUCTION
By letter dated March 5, 1997, as supplemented May 9, 1997, the Carolina Power
& Light Company'(the licensee) submitted a request for changes to the L
Brunswick Steam Electric Plant, Units 1 and 2, Technical Specifications (TS).
The requested changes would incorporate.a new TS for instrumentation 4
associated with auto:natic-isolation of a pathway for release of non-
.condensible gases from the main condenser. At power levels of 5 percent or less, mechanical vacuum pumps are used to remove non-condensible gases from the condenser using a pathway to the release stack that bypasses the normal holdup and. filter train..The proposed TS will require that four channels of the main steam line radiation - high radiation function be capable of tripping the mechanical vacuum pumps nnd closing an isolation valve in the release pathway. Surveillance requirements' are included in the TS to ensure the isolation instrumentation will perform its intended function.
By letter dated September 30, 1994, and supplemented March 24, 1995, the licensee requested elimination of the main steam line radiation monitor trip s
i signal to the condenser vacuum pumps and closure of the associated isolation i
valves. This request was based on the General Electric Company Licensing Topical Report NED0-31400 which was approved by the NRC staff by the Safety Evaluation dated May 15, 1991.
Further, a plant-specific calculation by NUS
.(NUS Calculation 8T12-M-02) demonstrated that in the event of a CRDA the
. radiation level in the control room would be below the permissible levels of General Design Criterion 19-and Standard Review Plan (SRP), Section 6.4.
By F
letter datei March 31, 1995, the NRC approved the change request for Brunswick, t.liminating_the above signal.
i On December 19, 1996, the licensee determined that the NUS calculation was in i
error, and in the event of.a CRDA without isolation of the. condenser vacuum
- pumps, the doses'in the main control room would exceed the SRP, Section 6.4 guidance.' To resolve this deficiency, the licensee proposes to restore to the~
original plant design and reinstall the main steam high radiation signal to trip the condenser vacuum pump and close the associated isolation valves.
The May 9,1997, letter provided clarifying information that did not change
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~ the initial proposed no significant hazards consideration determination.
97051500127 970509 PDR ADOCK 05000324 P
PDR 2
. 2.'0 EVALUATION In the March 5, 1997, letter the licensee stated that with the proposed changes, the probability of the vacuum pumps discharging contaminated steam into the main stack is very low for several reasons.
First, the condenser.
vacuum pumps are used for a limited time period when the plant'is below 5 percent power in Operational Condition 1 and 2.
When a condenser vacuum pump is not in operation, fis: ion product release through this path would not occur. Second, the isolati e of the vacuum pump system is required only when there is a CRDA. The licensee stated that a highly improbable combination of events have to happen for a CRD,\\ to occur. These events include erroneous selection and withdrawal of an ott-of-sequence rod by an operator,. a failure of the rod worth minimizer to block withdrawal of the out-of-sequence rod, and failure of the rod-to-drive coupling. The licensee probabilistic safety analysis-indicates that the probability of a CRDA is below 1E-6. per reactor over a 40-year time period. Third, in the event of a CRDA, the high radiation monitors in the main steam lines are designed to trip the condenser vacuum pumps and close the associated isolation valves in 5 seconds.
In other words, the condenser vacuum pumps can_ discharge contaminants only for 5 seconds.
Fourth, the safety-related main steam line radiation monitors provide a highly reliable means to automatically trip the respective condenser vacuum pump and close the associated isolation valve. The main steam line radiation-high logic consists of two independent trip systems, each with two channels 4
operating on one-out-of-two logic.
Furthermore, both trip systems must o)erate. to generate the isolation signal. This logic design is consistent with 2
t1e original approved plant design.
Fifth, in the event of a CRDA resulting i
in a high radiation level in the main steam lines, the main steam isolation valves are required to close in 5 seconds in compliance with the TS
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requirements.
i The licensee's submittal includes a calculation of main control room doses in the event of a CRDA, assuming that the main steam line radiation monitors isolate the condenser vacuum pumps in conformance to the SRP, Section 15.4.9.
The calculation indicates that the operator doses from a postulated CRDA are 23.2 rem thyroid and 0.05 rim whole body in the main control room area.
GDC-
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19/SRP Section 6.4 permits 30 rem thyroid and 5 rem whole body.
Doses of 0.16 1
rem thyroid and 0.015 rem whole body were calculated in the 2-hour exclusion
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area, and I rem thyroid in the low population zone. The calculated control room doses meet the indicated acceptance criteria, and the offsite doses are well below the acceptance criteria in the SRP and 10 CFR Part 100.
The amendment proposes a 12-hour time limit for the following Actions in new proposed TS 3/4.3.8, Condenser Vacuum Pump Isolation Instrumentation:
i a.
With one or more channels of the Main Steam Line Radiation-High Function i
for condenser vacuum pumps inoperable, restore the inoperable channel to operable status or place the inoperable channel or associated tri)
. system in trip or isolate the condenser vacuum pumps or isolate tie main j
steam lines or be in hot shutdown.
b.
-With condenser vacuum pump isolation capability not maintained, isolate the condenser vacuum pumps or isolate the main steam lines or be in hot shutdown.
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1 It further states that when a channel is placed in an inoperable status solely for the surveillance tests, entry into associated actions may be delayed for up to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> provided the condenser vacuum pump isolation capability.is
. maintained.
The amendment also proposed surveillance requirements which state that each channel of the Main Steam Line Radiation-High Function for condenser vacuum l
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pump isolation shall be demonstrated operable by:
a.
Performance of a channel check at least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> b.-
Perfonnance of a channel functional test at least once per 92 days J
c.
Performance of a channel calibration and logic system functional test at i
least'once per.18 months These requirements are in conformance with the original plant design for Brunswick Steam Electric Plant, Units 1 and 2, which included the condenser vacuum pump trip, and NEDC-30851P-A, Supplement 2, " Technical Specifications Improvement Analysis for BWR Isolation Instrumentation Common to Reactor Protection System and Emergency Core Cooling System Instrumentation," dated March 1989, which was previously approved by the NRC staff.
3.0 STATE CONSULTATION
l In accordance with the Commission's regulations, the State of North Carolina official was notified of the proposed issuance of the amendments.
The State J
official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes the Surveillance Requirements. The NRC staff has l
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 (62 FR 11224). 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.
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The NRC' staff has reviewed the licensee's evaluation and justification for
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reinstating the main steam radiation' monitor signal to isolate the condenser vacuum pump and to close the associated isolation valves.
Based on that review, the staff concludes that the licensee has performed a plant-specific l
calculation which confirms that reestablishment of the original plant design,
.which includes the above feature, will maintain the worst-case plant CRDA release below the acceptance criteria in the SRP and 10 CFR Part 100. The NRC I
. release below the acceptance criteria in the SRP and 10 CFR Part 100. The NRC staff further concludes that the proposed TS changes for the condenser vacuum pump trip and isolation are consistent with the BWR improved Standard TS and are, therefore, acceptable.
5.0 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:
S. Mazumdar Date:
May 9,1997 i
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