ML20082M417
| ML20082M417 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 04/14/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20082M403 | List: |
| References | |
| NUDOCS 9504240214 | |
| Download: ML20082M417 (3) | |
Text
j#M4g h
UNITED STATES g
g j
NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20666 4001 49.....
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 101 TO FACILITY OPERATING LICENSE NO. DPR-80 AND AMENDMENT NO. 100 TO FACILITY OPERATING LICENSE N0. DPR-82 PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON NUCLEAR POWER PLANT. UNIT NOS. 1 AND 2 DOCKET NOS. 50-275 AND 50-323
1.0 INTRODUCTION
By letter of August 17, 1994, Pacific Gas and Electric Company (or the licensee) submitted a request for changes to the Technical Specifications (TS) for Diablo Canyon, Units 1 and 2.
The proposed amendments increase the allowed outage time of the refueling water storage tank (RWST) for adjustment of boron concentration from one to eight hours. The licensee's application also requested deletion of the minimum RWST solution temperature which the staff has denied.
2.0 EVALUATION The RWST contains at least 400,000 gallons of borated water at a concentration between 2300 and 2500 ppm at a minimum temperature of 35 degrees F.
The RWST supplies borated water to both trains of the emergency core cooling system (ECCS) and the containment spray system during an accident. The safety injection, containment spray, and residual heat removal pumps are normally aligned to take suction from the RWST. The centrifugal charging pumps are normally aligned to the chemical and volume control system volume control tank and are automatically switched to take suction from the RWST at the injection phase of ECCS operation. The RWST is also a source of borated water for reactivity control during abnormal operating conditions and to the refueling cavity during refueling.
The RWST only supplies borated water upon ECCS actuation or when called upon during abnormal operating conditions or refueling. As such, its boron concentration is not affected by changing plant conditions or process variations.
Recirculation through the tank may occur for pump testing or operation of the purification system, but the borated water is returned to the RWST with its boron concentration unchanged.
Boron concentration can be changed through dilution with water of less boron concentration than that in the tank. However, the administrative controls for RWST makeup make inadvertent or incorrect makeup unlikely.
9504240214 950414 PDR ADOCK 05000275 P
. Boron concentration changes could affect several accident analyses:
large-and small-break loss-of-coolant accidents, inadvertent ECCS actuation, main steam line break, feedwater line break, and steam generator tube rupture.
The licensee stated that the impact of small changes in the borac concentration on the analyses for each of these accidents is not significant ind the small changes to the maximum limit on boron concentration would not have a i
significant effect on pH or on the maximum allowable time to switch to hot leg recirculation.
The change to an eight-hour allowed outage time of the RWST due to boron concentration may have positive effects on plant safety by reducing the probability of unnecessary plant transients and shutdowns. The additional time provides a better opportunity to determine the cause of any boron concentration problem, identify and institute appropriate corrective actions, and conduct any needed post-maintenance verification. Additionally, this change is consistent with NUREG-1431, " Standard Technical Specifications, Westinghouse Plants."
Any boron concentration changes which do occur are likely to be small and are not expected to increase significantly in the additional seven hours of allowed outage time. Additionally, the longer allowed outage time may enhance safety. The staff has reviewed the licensee's submittal and finds its assessment reasonable to support the increase of the allowed outage time of the RWST for adjustment of boron concentration from one to eight hours.
The TS, based on accident analyses assumptions, require that the temperature of the RWST water be maintained at least at 35 degrees F.
The licensee maintains that the temperature of the RWST water has never dropped below 47 degrees F since 1969 based on an extrapolation of site temperature data to what the temperature of water in the RWST would have been. This historical assessment does not preclude the possibility of a future period of cold weather that may adversely affect the temperature of the water in the RWST.
Given the importance of the availability of the RWST, the staff has denied the licensee's request to remove the minimum temperature requirements and the associated action statement from the TS.
The staff, however, has agreed that the requirements of TS 3/4.1.2.6 are duplicative of the requirements contained in TS 3/4.5.5 in that they both identify the same RWST limiting conditions for operation and action statement.
Therefore, the requirements of.TS 3/4.1.2.6 as they apply to the RWST have been deleted as requested by the licensee with no adverse safety impact and with an increase in clarity of the TS.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the California State official was notified of the proposed issuance of the amendments. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
These amendments change a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change 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 considera-tion, and there has been no public comment on such finding (59 FR 51621).
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.
5.0 LONCLUSION 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:
M. A. Miller Date:
April 14, 1995
-