ML20091Q407

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Safety Evaluation Supporting Amend 66 to License NPF-30
ML20091Q407
Person / Time
Site: Callaway Ameren icon.png
Issue date: 01/24/1992
From:
Office of Nuclear Reactor Regulation
To:
Shared Package
ML20091Q406 List:
References
NUDOCS 9202040378
Download: ML20091Q407 (3)


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SAFETY EVALVATION BY ThE OFFICE OF NUCLEAR REACTOR REGULATION RELAT[D TO AMENDMINT NO. 60 TO FACILITY OFUiKTING LICTIST~RD~~IFT-30 UNION ELECTRIC COMPANf CALLAWAY PLANT, UNIT 1

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1.0 INTRODUCTION

In its letter dated March 15, 1991, as supplemented by letters dated August 15, 1991 and January 23, 1992, the Union Electric Company (the licensee) requested a revision to Technical Specification 3.4.6.2.f and the associated Bases for the Callaway Plant, Unit 1.

The proposed revision would replace the present maximum allowable leakage rate of 1-gallon per minute (

any of the reactor Coolant system presture isolation valves (PlVs) gpm) from specified in Table 3.4-1 of the Callaway Tecanical Specifications (TSs).

This new set of maximum allowable leakage rates would be dependent on the size of the P!Vs. The proposed maximum allowable leakage of these P!Vs would be limited to 0.5 gpm per nominal inch of valve size up to a maximum of 5 gpm.

Additionally, the licensee proposed in its application cited above that Table 3.4-1 be expanded to provided a more detailed description of the 35 affected PlVs and to correct some valve identification numbers and descriptions.

2.0 EVALUATION The subject TS (i.e., TS 3.4.6.2) establishes six separate criteria of reactor coolant system (RCS) maximum allowable leakage rates. One of these is the maximum allowable leakage rate from the RCS PlVs which are presently limited to 1 gpm for each PlV (TS 3.4.6.2.f).

The licensee proposed that this single value be replaced by limiting leakage rates dependent on the nominal diameter of the PlYs.

Specifically, the licensee has proposed that the maximum allowable leakage rate for the 35 P!Vs listed in Table 3.4-1 of the Callaway TSs be established as 0.5 gpm per nominal inch of valve size up to a maximum value of 5 gpm at an RCS pressure of 2235 t20 pounds per square inch gauge (psig).

The present value of the maximum allowable leakage iate of 1 gpm for each PlV, independent of size, is arbitrary in that this TS limit does not recognize that leakage through check valves tends to be larger as valve size increases.

(This is related to the leakage area being proportional to the valve diameter.)

As a result, this use of a single, relatively low limiting value of PlV leakage for the larger valves requires them to be reworked for the same limiting leaka? rate as that for a small PlV.

However, a measured leakage rate of 1 gpm from a 2-inch Ply is more significant than a leakage of 1 gpm from a 10-inch PIV in that it is indicative of greater degradation.

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. The net result is that the larger PlVs will tend tr be reworked more frequently t' an justified, considering the signifi:ance of the 1 gpm leakage through these larger valves. The licensee 's proposal, to the extent that it reduces excessive reworking of the larger PlVs will thereby reduce radiation exposure to the plant operating personnel.

The licensee's proposal to revise the 1e'akage limit for the PlVs in TS Table 3.4 1 introduces a more rational correlation between the size of a Ply and its limiting leakage rate.

Inasmuch as thin proposed revision does not change the limits on identified or unidentified leakage from the RCS, there will be no significant increase in the total leakage outside the reactor priniary containment and no significant increase in the amount of radioactivity released to the environment under normal or accident conditions.

The proposed change will allow operaticn with sone increase in the leakage from certain PlVs, however plant operation will continue to be restricted by the TS limits on total leakage. The slight increase in allowable leakage from individual PlVs is still sufficiently conservative to permit the identification of significant valve degradttion. Additionally, the Bases section is revised to delete the specific reference to 1 gpm leakage for any RCS pressure isolation valve, consistent with the proposed change to TS 3.4.6.2.f.

The licensee stated in its supplemental letter dated August 15,1991 that there is more than sufficient pressure relief capacity downstream of the PIVs to prevent overpressurization of piping and equipment as a result of the proposed higher limiting leakage rates.

Based or discussions with N staff, the licensee revised its original request on January 23.195"'

The revised request changed the leakage limit for va hes which are 2-inche u smaller to 0.5 gpm per nominal inch of valve size. This change is consistent with the Standard Technical Specifications. The revised limits are more conservative than those originally proposed by the licensee and therefore, this revision does not alter the staff's original proposed no significant hazards determination.

Accordingly, the NRC staff finds the licensee's proposal acceptable on the basis that it will tend to decrease radiation exposure to plant operating personr4 and will allow continued plant operation without a significant increase in the resulting leakage frcm the reactor primary containment.

The staff concludes, therefore, that there is no significant increased risk to public health and safety.

3.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Missouri State official was notified of the proposed issuance of the amendment.

The State official had no comments.

4.0 ENVIRONMENTAL CONSIDERATION

This amendment involves a change to a requirement with respect to the instal-lation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.

The staff has determined that the amendment involves rc 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 cumula ve occupational radiation exposure.

The Commission has previously issued a pr'un -

finding that this amendment involves no significant hazar i ',;iderat, and there bas been no public comment on such finding (56 FR 24220).

Accordingly, this amendment meets 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 issu.ce of this amendment.

5.0 CONCLUSION

The staff has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safet be endangered by operation in the proposed nanner, (2) y of the public will not such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor:

M. D. Lynch Date:

January 24, 1992

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