ML20136B805

Safety Evaluation Supporting Amend 90 to License DPR-3

ML20136B805
Person / Time
Site:	Yankee Rowe
Issue date:	12/16/1985
From:	Office of Nuclear Reactor Regulation
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ML20136B795	List: ML20136B790 ML20136B797 ML20136B805
References
NUDOCS 8601020923
Download: ML20136B805 (5)

Text

a nr uq jog UNITED STATES

. - o NUCLEAR REGULATORY COMMISSION 7, ;E WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 90 TO FACILITY OPERATING LICENSE N0. DPR-3 YANKEE ATOMIC ELECTRIC COMPANY YANKEE NUCLEAR POWER STATION DOCKET NO. 50-29

1.0 INTRODUCTION

By letter dated May 7, 1985, the Yankee Atomic Electric Company (YAEC) i submitted a reonest for changes to the Yankee Nuclear Power Station 3 Technical Specifications (TS).

i The proposed amendment would add limiting conditions for operation and surveillance requirements to limit Emergency Core Cooling System (ECCS) leakege to less than 50 gallons per day (gpd).

A Notice of Consideration of Issuance of Amendment to License and Proposed l No Significant Hazards Consideration Determination and Opportunity for i Hearing related to the requested action was published in the Federal Register on July 17, 1985 (50 FR 29022). No comments or requests for s hearing were received.

! 2.0 EVALUATION

2.1 Background

1

• s a result of the Systematic Evaluation Program Topic XV-19 review, it was suggested by the licensee that the limit for ECCS leakage be set at 20 gpd as a means of limiting the calculated doses from the postulated leakage of recirculated core cooling water outside containment, post-LOCA.

, At the time, the licensee had indicated that the leakage was approximately 10 gpd. However, the licensee has determined that under certain circumstances, the leakage from the ECCS pumps could exceed the 10-20 gpd b

,com range. Therefore, the licensee has proposed to limit the ECCS leakage to 50 gpd. The licensee's submittal indicates its conclusion that the LOCA g%' doses (including short and long term ECCS leakage dose contribu,tions) would gon be within 10 CFR 100.11 dose guidelines.

c)O Ng

?.2 Staff Evaluation o

oS The staff has done an independent evaluation of the LOCA dose in order

@< to determine if the radiological consequences of such an accident meet g the exposure guidelines of 10 CFR 100.11. The staff analysis includes l on the contribution from containment leakage post-LOCA, leakage from i G)O Engineered Safety) long term leakage Feature

, and shine(ESF) systems or direct radiation outside containment through (short and the containment.

- The assumptions used in the staff's evaluation are listed in Table 1; the calculated doses are shown in Table 2. The dose from the containment leakage and ESF leakage outside containment was calculated by the methods cor,tained in Standard Review Plan (SRP) 15.6.5, Appendices A and B.

The staff assumed that decay was the only removal mechanism for the fission products assumed to be released to containment. For the iodine postulated to be released from leaking ESF components outside containment, the staff gave no credit for hold-up, plate-out, filtration and ground deposition, and assumed that all piping penetrating the primary containment meets General Design Criteria 54-57. However, the staff did depart from the SRP assumptions with regard to modeling the ECCS leakage for long term and the flashing fraction for both long and short term ECCS leakage. It was our judgment that assuming the ECCS leakage to be 1.5 times the TS value (compared to the SRP value of 2) is sufficiently conservative considering the other conservatisms in the analysis, and the fact that ECCS pressures are lower than the ECCS pressures for contemporary reactors for which the SRP was intended. Furthemore, it was detemined that the 10% flashing fraction recommended by the SRP was too conservative in view of the fact -

that the LOCA thermodynamic analysis indicates a ::ignificantly reduced flashing fraction (approximately 4%). The staff assumed 6% flashes to allow for margin. The shint or direct gama dose evaluation is not considered in SRP 15.6.5, because the modern plants for which SRP 15.6.5 was written have thick concrete walls which reduce the potential shine dose to a negligible amount. However, the Yankee containment is a steel sphere, which provides far less accident shielding from shine than a steel-lined reinforced concrete containment. Guidance for the evaluation of this dose pathway is found in the note following 10 CFR 100.11, which states, "The calculations described, in Technical Information Document 14844 may be used as a point of departure for consideration of particular site requirements which may result from evaluation of the characteristics of a particular reactor...." Therefore, the j staff decided that it should evaluate the shine doses and used the calculative l method outlined in TID-14844. More recently developed ways of calculating the shine dose may give a more accurate answer, but the shine doses shown in Table 2 are so small that refining the calculation would make little difference.

2.3 Summary The calculated thyroid and whole body doses at the Exclusior Area Boundary and the outer boundary of the Low Population Zone as shown in Table 2 are within the dose guidelines of 10 CFR 100.11. The proposed changes to the TS are, therefore, acceptable.

3.0 ENVIRONMENTAL CONSIDERATION

This amendment involves a change to a requirement with respect to the installation or use of facility components located within the restricted area as defined in 10 CFR Part 20 and changes to the surveillance requirements. ~ Tha staff has 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 offsite and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that this amendment

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4 involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, this amendment meets the eligibility criteria for cateaorical exclusion set forth in 10 CFP 51.22(c)(9). Pursuant to10CFR51.22(b)r,oenvironmentalimpactstatementorenvironmental assessment need be prepared in connection with the issuance of this amendment.

4.0 CONCLUSION

The staff has concluded, based on the considerations discussed above, that:

(1) there is reasonable assurance that the health and safety of the will not be endangered by operation in the proposed manner, and such (2) public activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.

5.0 ACKNOWLEDGEMENT 1his Safety Evaluation has been prepared by L. Beli and J. Clifford.

Dated: December 16, 1985 l

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.- TABLE 1 i l ASSUMPTIONS USED IN THE CALCULATION OF OFFSITE DOSES S FOLLOWING A DESIGN BASIS LOCA

~

Reactor power level 600 MWt Fraction of noble gases available for release 100%

Fraction of iodines available for release 25%

Containment leak rate 0.2% per day, first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> For shine dose:

distance to Exclusion Area Boundary (EAB) 3100 feet  :

distancetonearestLowPopulationZone(LPZ) outer boundary 4452 feet .

creditforvaporbarrier(containment) .

shielding none -

calculative method AsinTID-14844(100%

of the noble gases,

! 50% of the iodines, and 1% of the solid ,

fissionproducts).

ESF leakage 75 gpd for 1/2 hour to R

Long ters 30 days after -

accident. -

Short tern passive failure 50 gpm for 30 minutes starting 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after accident.

Fraction of core inventory in ECCS water 50% of iodine, no noble gases Fraction of iodine in leaked water released to environment 65 Atmospheric Dispersion Coefficients 0-2hr.EAB2.8x10-fsec/d

.-0-8 hr. LPZ 2.8x10~ sec/m -

8-24 hr. LPZ 1.9x10' sec/

24-96 hr. LPZ 1.6x10~ sec/

96-720 hr. LPZ 1.0x10 sec/

- , . . , , ~ , , , - , . , - ,,-.,nv ,, ,,n.. ,--- ,.,.,.,,,,,.- ,yn nm en,_,m.~.,, - _ - . _ . ~,y

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.- TABLE 2 CALCULATED OFFSITE DOSES RESULTING FROM A LOCA Exclusion Area Nearest Outer F,oundary" of Low Boundary (0-2 hours) Population Zone (0-30 days)

Dose in rems Dose in rems Thyroid 'Whole Body Thyroid Whole Body Containment Leakage 162 1.0 244 0.4 Leakage from ESF components 4 <1 50 0.1 Shine (directgamma) -

1.4 -

0.2

Total 166 2.5 294 0.7 l

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