ML20028E591
| ML20028E591 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 01/14/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20028E587 | List: |
| References | |
| NUDOCS 8301280034 | |
| Download: ML20028E591 (4) | |
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4 SAFETY EVALUATION AMEllDt!ENT f40.1 T0 flPF-15 SAN ONOFRE NUCLEAR GENERATING STATI0ft, UNIT 3 DOCKET NO. 50-362 Introduction by letter dated November 19, 1992, SCE requested a change to San Onofre Unit 3 Technical Specification 3.9.8.2, Refueling Operation, Low Water Level.
The.
proposed change allows the shutdown cooling trains to be removed from operation for up to I hour per 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> period during performance of core alterations in the vicinity of the reactor pressure vessel hot legs..The staff evaluation of this proposed change is given below.
Telephone authorization to implement this proposed change was given to SCE on November 19, 1982.
i In addition, by letters dated Decenber 20, 21, and 22, 1982, SCE requested a revision to San Onofre Unit 2 Technical Specification 3/4.3.2, Table 3.3-5.
The proposed change deletes the requirement that the couponent cooling water (CCW) non-critical loop containment isolation valves and the CCW critical /
non-critical loop isolation valves isolate on low pressurizer pressure. All these valves will continue to isolate on high containrent pressure (about 3 psig).
The CCW critical /non-critical loop isolation valves will continue to isolate on low-low CCW surge tank level.
I On December 23, 1982, Amendment f!o. 12 to the San Onofre Unit 2 license, NPF-10, was issued, authorizina this proposed change. By letter dated January 7,1983, SCE requested that the same change he made in the San Onofre Unit 3 Technical Speci ficatinns.
The staff evaluation of this proposed change is given below.-
Evaluation, (1) Renoval of SDCS fron operation during core alteration.
Core alternations in the vicinity of the reactor vessel hot legs with shutdown cooling in operation can result in danage to fuel oundles due to fice induced rnovement caused by a000 gpm shutdown cooling flow.
Specification 3.9.8.1, Refueling Operations, High Water Level, already contains this provision for the same reason. Fornerly, the. Refueling l
Operations High Water Level and Low Water Level Technical Specifications were conbined with this provision. 'In the most recent revision to the Combustion Engineering Standard Technical Specifications, the one specifi-cation was separated into the two presently existing Technical-Specific-cations and the provision for renoving the shutdown cooling trains from operation was inadvertently deleted from the Low Water Level Technical Specification. Operations involving a change in RC3 boron concentration are not allowea in this provision to avoid the occurrence of a boron dilution event.
The naximun of one hour per eight hour period allowed omcr >
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2-in this mode is consistent with the provisions of the High Water Level Technical Specification, FSAR Section IS.4.1.4.3c and SCE response to NRC questions 212.124'and 212.152 concerning boron 6 1ution events.
Therefore, the staff finds the proposed change acceptable. As stated above, telephone approval of this change to the San Onofre Unit 3 Technical Specifications was given on Novenber 19, 1982.
(2) Renoval of SIAS fron non-critical CCU loop isolation valves.
In its Decenber letters, SCE stated that renoval of the Pressurizer Pcessure-Low isolation signal from these valves will permit the CCW systen to continue cooling non-critical loop loads such as the Reactor Coolant Pung (RCP) notors and seals and the control Element Drive Mechanism (CEDM) windings during certain transient events. Under the previous Technical Specifications, these transient events would unnecessarily require that cooling to the RCP motor and seal and CEDM winding be terninated.
SCE stated that the continued cooling allowed by the proposed change to the Technical Specification w111 mininize cumulative danage to the RCP punps seals caused by unnecessary interruptions of CCW. Minimization of such cunulative damage to the RCP seals will increase the availability of the RCPs and reduce the probability of RCP seal failures.
As indicated by SCE in their letters, the proposed change to the Technical Specifications will only affect the response of the CCW systen.for those transient events which result in Pressurizer Pressure-Low but not Contain-ment Pressure-High. Such events are pressurizer pressure control systen failures, nain steau or feedwater systen control system or piping failures outside containment, and small steon, feedwater and reactor coolanc system piping failures inside containment.
For these events, the following analyses and Conclusions are presented by SCE:
(a) The CCW Systen design has been reviewed and it has been verified that flow and heat capacity are adequate to sinultaneously serve all essential and non-essential loads with the exception of the Shutdown Cooling Heat Excnangers (SDCHX). The SDCHX's are isolated until they receive the Containment Spray Acutation Signal at approximately 16 psiO Containment pressure. Because the proposed signal to isolate the essential from the non-essential loads occurs at approximately 3 psig containment pressure (on Containnent Isolation Actuation Signal), the CCW systen capacity will not be exceeded.
(b)
Isolation of the critical CCW loops from the non-critical loop occurs on low-low CCW surge tank level, thereby protecting the critical loops fron non-critical loop failures.
SCE stated that each of the safety analyses of Section 15 of the FSAR have been examined, and the proposed change will not inpact the analyses.
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, (c) While the proposed change will reduce the diversity of the actuation signal to the non-critical loop CCW containment isolation valves, the overall result of the change will be to allow operation of the RCPs durinq a wider range of transient events.
Since RCP operation can nitigate the consequences of nany accident sequences, SCE argues that the proposed change results in increased plant safety, on balance.
The NRC staff has reviewed the SCE letters dated December 20, 21, and 22, 1982 and January 7,1983, and has discussed the issue with SCE in a neetinq on December 21, 1982.
The staff concurs with SCE's conclusions, for the reasons given above. Conscquently, the staff finds the proposed chanqes to Technical Specification 3.4.3.2 to be acceptable.
This change has previously been authnrized for San Onofre Unit 2 by Amendnent 12 to frF-10, dated December 23, 1982.
(3) Evaluation of related issues.
O m ng the course of the staff's review of the proposed change, it became clear that the non-critical CCW containnent penetrations do not meet the applicable staff criteria or the criteria defined in the FSAR. Specifically, the non-critical CCy loop can not be shown to rwet the criteria specified in the FSAR for systems which neet General Design Criterion (GDC) 57, since the loop inside containment is not nissile and pipe-whip protected, and the components served are not seismic Category I.
Therefore, the isolation provisions uust neet GDC 56, which requires two automatic isolation valves for each line penetrating containnent. The present design has two isolation valves per line, but only one' of the valves isolates autonatically.
The other has remote-manual actuation.
At a meetinn on December 22, 1932, this issue was discussed with SCE. By its letter dated December 22, 1982, SCE connitted to correct the situation for both Unit 2 and 3 within 90 days by changing the remote-nanval valves (HV-6223 and 6236) to automatic isolation.
The 90 day time period was justified on the basis of material delivery tine and installation and testing tine.
In the interin, justification for continued operatioP will be based on prncedures requir ng operator verification of non-critical loop isolation, and operator action to close the renote-manual valves should the autonatic valves fail to close.
SCE further stated that the remote-nanual valves will be unlocked to allow closure by the operators, rather than locked open as stated in the FSAR.
The NRC staff has reviewed the SCE letter of ';ecember 22, 1982, and has discussed the issue with SCE, and has cencluded that operation prior to installation of the automatic isolation signal to valves HV-6223 and 6236 is acceptable, based on (1) automatic isolation of valves HV-6211 and 6216 which are in series with HV-6223 and 6235, and (2) the ability to promptly isolate valves HV-6223 and 6236 from the control roo'n should the need arise.
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. Environnental Consideration
!!c have determined that this amendment does not authorize a change-in effluent types or total amount nor an increase in power level and will not 4
result in any significant environnental impact. liaving made this deternination, we have further concluded that this amendment involves i
action which is insignificant from the standpoint of environmental impact and pursuant 10 CFR Section 51.5(d)(4), that an environmental inpact statement or negative declaration and environnental impact appraisal need not be prepared in connection with the issuance of this amendment.
Conclusion Based upon our evaluation of the proposed changes to the San Onofre,? Unit 3 Technical Specifications, we have concluded that:
(1) because this smendment does not involve a significant increase in the probability or conseg sences of accidents previously considered, does not create the possibility )f an dCCident of a type different froa any evaluated previousiy, and does not involve a significant decrease in a safety nargin, this amendment does not involve a significant safety hazards consideration; (2) there is reasonable
. assurance that the health and safety of the public will not be endangered by operation in the proposed nanner, and (3) such activities will be con-oscted in conpliance with the Ccenission's regulations and the issuance of this emend ent will not be inimical to the common defense and security or to the health and safety of the public. lie, therefore, conclude that the proposed changes are acceptable.
Dated: JAN 1 4 I983 6
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