ML20072Q076
| ML20072Q076 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 11/26/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20072Q075 | List: |
| References | |
| NUDOCS 9011300111 | |
| Download: ML20072Q076 (3) | |
Text
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SAFETY EVALVAT_ ION BY THE OFFICE _OF NUCLEAR _ REACTOR _ REGULATION RELATED_TO AMENDMENT NO. 150 i
TO FACILITY _ OPERATING _L_ICENSE N0_._DPR NORTHEAST NUCLEAR _ ENERGY COMPANY,'ET AL.
MILLSTONE NUCLEAR _ POWER STATION, UNIT __NO. 2 DOCKET N0_.__50-336
1.0 INTRODUCTION
By application for license amendment dated August 7, 1990, Northeast Nuclear Energy Company (the licensee) requested changes to the Technical Specifications (TS) for Millstone Nuclear Power Station, Unit 2.
The proposed amendment would change Technical Specification 3.9.3.2 to add a requirement that the Spent Fuel Pool (SFP) bulk temperature be maintained below 140 degrees F at all times and would remove the current requirement that the SFP cooling trains be operable in Modes 5 and 6 whenever the most recent 1/3 core off-load has decayed less than 21 days (504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br />) from subcriticality and the shutdown cooling is not being used to cool the SFP. Action statements would be added to require (1) immediate actions to restore the temperature below 140 degrees F, (2) within one hour suspension of fuel: movement within the SFP, (3) within one hour isolation of the SFP cleanup demineralizers, and (4) recording SFP temperature at least once per 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> if the Limiting Condition for Operation (LCO)isnotsatisfied. The surveillance requirement would also be revised to monitor the SFP temperature every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
2.0 EVALUATION The current TS requires that both trains of SFP cooling be operable whenever the most recent 1/3 core offload has decayed less than 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br /> (21 days) from subcriticality.
It is applicable only in Modes 5 and 6 (cold shutdown and refueling) and is not applicable'when the shutdown cooling (SDC) is being used to cool the SFP. Action statements require (1).immediate initiation of actions to restore both trains of SFP cooling, (2) within one hour, suspend all fuel movement in the SFP, and (3) within one hour, isolate the SFP cleanup demineralizers if the LCO is not satisfied. The current TS (TS 3.9.3.3) also requires the reactor be maintained in Mode 5 or 6 until the most recent 1/3 core offload in the SFP has decayed for greater than 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br /> from subcriticality.
During refuel or core offloading or immediately upon entry into Mode 5 from Mode 6 with the most recent 1/3 core offload decayed less than 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br /> from criticality would be the times when the greatest SFP cooling is required. The licensee has determined that, at most times, the SFP temperature can be 9011300111 901126 PDR ADOCK 05000336 P
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. maintained below 140 degrees F with only one train of SFP cooling available.
The proposed TS would require that the plant immediately take actions to restore the SFP to 140 degrees F or less, if the temperature limit is exceeded. The licensee has indicated in the application for amendment that even assuming the initial pool temperature is at 140 degrees F when SFP cooling is lost, the minimum time to boiling (212 degree F))is estimated to be 8.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. Also, with the plant in Mode 6 (refueling with complete core offload assuming initial pool temperature at 140 degrees F and SFP cooling lost, the minimum time to boiling is estimated to be 3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.
By letter dated February 22, 1989, on a similar subject, the licensee established that, given a single failure and if one train could not provide enough cooling with the plant in Mode 5 (cold shutdown with the vessel head on), SDC could be initiated within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to provide cooling to the SFP. The licensee has indicated that the SFP liner, building structures and racks have been qualified for a maximum water temperature of 212 degrees F.
Therefore, even in the worst-case scenario, the proposed change would allow sufficient time for the operators to reinitiate SFP cooling or lineup SDC and ensure the design limits of the associated components are not exceeded.
During normal operation in Modes 1 through 4 both SFP trains would be available with one train capable of providing sufficient cooling to maintain the SFP temperature equal to or less than 140 degree F.
Since the proposed TS would ret:,in the requirement to suspend fuel movement within the SFP if the SFP terperature exceeded 140 degrees F, the SFP could be evacuated to ensure per!.onrel safety in case of SFP heat-up.
The proposed TS would a'so retain the requirement to isolate the SFP cleanup demineralizers within rne hour if the SFP temperature exceeded 140 degrees F.
This would assure protection of the deminerlizer resins from excessive temperature.
To assure that the proposed LCO would be met, the proposed surveillance requirement would verify the SFP temperature is less than or equal to 140 degrees at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Also, to assure that the proposed LC0 is met, if SFP temperature exceeds 140 degrees, the licensee would be required to monitor the SPF temperature every 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
We have evaluated the proposed changes to the TS and have determined that they are acceptable.
3.0 ENVIRONMENTAL CONSIDERATI0tl This amendment changes a requirement with respect to the installation or use of a facility component located within the restricted areas as defined in 10 CFR Part 20 and changes surveillance requirements. We have determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released 1
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l offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The staff has previously published a proposed finding that the arondment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, the amendment meets the eli forth in 10 CFR 51.22(c)(9)gibility criteria for categorical exclusion set Pursuantto10CFR51.22(b),noenvironmental impact statement or environmental assessment need be' prepared in connection with the issuance of the amendment.
4.0 CONCLUSION
We have 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, and (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or the health and safety of the public.
Dated: November 26, 1990 P_rjncjpal _ Contrjbutor:
G. S. Vissing