ML20057B970
| ML20057B970 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 09/20/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20057B969 | List: |
| References | |
| NUDOCS 9309240220 | |
| Download: ML20057B970 (4) | |
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WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.182 TO FACILITY OPERATING LICENSE NO. DPR-53 AND AMENDMENT NO.159 TO FACILITY OPERATING LICENSE NO. DPR-69 BALTIMORE GAS AND ELECTRIC COMPANY CALVERT CLIFFS NUCLEAR POWER PLANT. UNIT NOS. 1 AND 2 DOCKET NOS. 50-317 AND 50-318
1.0 INTRODUCTION
By letter dated April 1,1993, the Baltimore Gas and Electric Company (the licensee) submitted a request for changes to the Calvert Cliffs Nuclear Power Plant, Unit Nos. I and 2, Technical Specifications (TSs). The requested changes would revise TS 3/4.1.2, "Boration Systems." The proposed changes and clarifications will separate the requirements for mitigating small break loss-of-coolant accidents (SBLOCA) from the requirements for providing emergency baration. The changes provide needed clarification to ensure that the appropriate boration lineups are operable during applicable _ modes of operation. Potential combinations of water sources and flow paths which do not meet the single failure criterion and the potential need.for operator action during the first 10 minutes of a SBLOCA will be eliminated. The TS Bases Section 3/4.1, " Reactivity Control Systems," will also be revised to support the proposed changes. The proposed changes do not add, revise, or delete any of the existing TS requirements.
The specific changes and clarifications proposed to separate the requirements for mitigating a SBLOCA from the requirements for providing emergency boration are:
TS 3.1.2.6, Boric Acid Pumps - Operating, limiting Condition for Operation (LCO), will be changed to include a reference to TS 3.1.2.8.a, Charging Pump Emergency Core Cooling (ECCS) Subsystems, LCO.
TS 3.1.2.8, Boration Systems Borated Water Sources - Operating, will be changed to Boration Systems Charging Pump ECCS Subsystem, LCO, and will only contain the requirements which need to be met to mitigate a SBLOCA. This LC0 will continue to be applicable to Mode I when greater than 80 percent of rated thermal power. The previous requirements for providing emergency boration capability are moved to TS 3.1.2.9, Borated Water Sources - Operating, LCO.
The footnote on TS 3.1.2.9, Borated Water Sources - Operating, LCO, which makes the LCO applicable to Mode I when less than or equal to 80 percent of rated thermal power, is removed. The LCO, as changed, will be applicable in 9309240220 930920 PDR ADDCK 05000317 P
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Modes 1 through 4 to asscre the requirements needed for emergency boration are available. The LC0 requirements necessary to mitigate an SBLOCA for Mode I when greater than 80 percent of rated thermal power will be contained in TS 3.1.2.8, as previously noted.
2.0 BACKGROUND
As noted in the licensees submittal, the chemical volume and control system (CVCS) is designed to control the reactor coolant volume, regulate reactor coolant chemistry, and maintain reactor coolant radioactivity at the desired level s.
The boron concentration of the reactor coolant is controlled by the CVCS to optimize the position of the control element assemblies; compensate for reactivity changes caused by variations in the temperature of the reactor coolant and by core burnup; and to provide shutdown margin for maintenance, refueling or emergencies.
The portion of the CVCS known as the boration system consists of a batching tank for preparing boric acid solution, two tanks for storing the solution, and two pumps and two gravity feed lines for supplying boric acid solution to the makeup system. The refueling water tank (RWT) also provides a source of borated water.
For emergency boration i
purposes, the boration system is required to maintain a minimum 3.0 percent delta k/k Shutdown Margin from all operating conditions during xenon decay and cooldown to 200 *F.
The requirement for providing emergency boration I
capability in Modes 1 through 4 can be accomplished by having any two of the three borated water sources operable.
A reanalysis was previously performed by the licensee for a SBLOCA and the TSs were revised for both units to support the reanalysis. The reanalysis assumed a reduction in high pressure safety injection (HPSI) flow capacity which was compensated for by crediting flow from one charging pump. Charging pump flow was required when operating in Mode 1 above 80 percent of rated thermal power.
The current TSs for barated water sources and flowpaths (which are applicable above 80 percent of rated thermal power) combine the requirements for providing emergency boration and the requirements for mitigating a SBLOCA.
These TSs allow potential combinations of sources and flowpaths which may not meet the single failure criterion and the time response requirement of the l
ECCS to provide the charging pump flow necessary to mitigate the consequences of a SBLOCA.
3.0 EVALUATION As detailed above, the current TS allow potential combinations of borated i
water sources and flowpaths which may not meet the single failure criterion (due to their associated power sources) for mitigating a SBLOCA.
In addition, the current TS could also be interpreted to allow the RWT to be credited as a source of borated water to mitigate a SBLOCA. The design of the RWT requires operator action to open the valve from the RWT to the charging pamp header.
The SBLOCA analysis dces not credit operator action during the first 10 minutes of the event; thus, no credit was taken for the RWT as a source of borated water. Although the RWT can not be given credit as a source of
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borated watn se the SBLOCA, it is an acceptable source for emergency l
boration when operating in Modes 1 through 4.
The proposed TS changes would eliminate the possibility of misinterpretation of the existing TSs in relation to the requirements to mitigate a SBLOCA.
l Proposed TS 3.1.2.8 will only contain the LC0 requirements for the charging; pump ECCS subsystem necessary to mitigate a SBLOCA. The LC0 would require that boric acid storage tank (BAST) 12-(BAST 22 for Unit 2) and its associated j
heat tracing and flow paths via the boric acid pump be operable. The LC0 also l
requires either a flow path via BAST 12 (BAST 22 Unit 2) gravity feed connection or BAST 11 (BAST 21 for Unit 2) gravity feed connection and their i
associated heat tracing be operable.
These borated water sources and flow paths, including their associated heat tracing and power sources, meet the single failure criterion and do not require operator intervention during the first 10 minutes of an SBLOCA as assumed in the SBLOCA analysis.
q The staff has determined, based on the above, that the proposed changes are acceptable.
Proposed TS 3.1.2.9 will contain the LC0 requirements for emergency boration during Modes 1, 2, 3 and 4.
The deletion of the footnote which indicates that it is applicable in Mode I when at or below 80 percent of rated thermal power will be deleted. This footnote is no longer required because of the changes i
to TS 3.1.2.8 detailed above and is, therefore, acceptable.-
The proposed changes to TS 3.1.2.6 contains the LCO requirements for the boric acid pumps which are necessary to assure that the operability requirements for-the emergency ECCS subsystem in TS 3.1.2.8 and operability requirements for l
the emergency boration system in TS 3.1.2.9 can be met. Therefore, the staff has determined that the proposed changes are acceptable.
i The action statements for TSs 3.1.2.6, 3.1.2.8, and 3.1.2.9 have been adjusted I
to support the changes described above which separate the requirements for i
mitigating an SBLOCA from the requirements for providing emergency boration.
The action statements will assure that appropriate steps.are taken within the times specified, which are consistent with the times specified in the current TSs, when the respective LCOs can not be met. The associated surveillance requirements.in the proposed TSs will not result in any changes in the current TS surveillance requirements for the ECCS subsystem or the emergency boration system. Therefore, the staff has determined that the proposed changes are acceptable.
The TS Bases Section 3/4.1.2 is updated to reflect the proposed changes in
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. TSs 3.1.2.6, 3.1.2.8, and 3.1.2.9 and is, therefore, acceptable.
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4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Maryland State official was notified of the proposed issuance of the amendments. The State official had no comments.
5.0 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 change the surveillance requirements. 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 (58 FR 25852). 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 i
defense and security or to the health and safety of the public.
Principal Contributor:
Daniel G. Mcdonald Date: September 20, 1993 i
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