ML20081J038
| ML20081J038 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 03/22/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20081J035 | List: |
| References | |
| NUDOCS 9503270075 | |
| Download: ML20081J038 (3) | |
Text
.. _ _
pf *'*v f e
4 UNITED STATES
- ., e t
i 9
' NUCLEAR REGULATORY COMMISSION i
'f WASHINGTON, D.C. 2006 0 0001 l
s...../
l i
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMEN 0 MENT NO. 160 TO FACILITY OPERATING LICENSE NO. DPR-35
~f i
BOSTON EDISON COMPANY PILGRIM NUCLEAR POWER STATION i
DOCKET NO. 50-293 3
1.0 INTRODUCTION
f By letter dated November 22, 1994, the Boston Edison Company (the licensee) i submitted a request for changes to the Pilgrim Nuclear Power Station Techt' cal Specifications (TSs). The requested changes would revise the allowable letk rate for the main steam isolation valves (MSIVs) from the current'11.5 i
standard cubic feet per hour (scfh) for each valve, to a maximum combined main steam line leak rate of 46 scfh.
I i
2.0 EVALUATION j
Each of Pilgrim's four main steam lines contain two (inboard and outboard),
quick-closing MSIVs. The safety function of the MSIVs is to isolate the l
reactor system to minimize loss-of-coolant inventory and provide primary containment to limit radiological release.
In the case of a steam line break, as evaluated in Updated Final Safety Analysis Report (UFSAR) Section 14.5.4, closure of the MSIVs terminates the blowdown of reactor steam in sufficient i
time to prevent an uncontrolled release of radioactivity from the reactor' vessel to the environment.
In the case of a loss-of-coolant accident (LOCA),
i as evaluated in Section 14.5.3 of the UFSAR, the MSIVs isolate the reactor from the environment and prevent the direct release of fission products from the containment.
The allwable leak rate of 11.5 scfh specified for each of the MSIVs is used to quantify a maximum volume of primary containment atmosphere that can bypass the secondary containment and leak directly to the envirannent following a design basis LOCA. The TSs requirements assure that this MSIV leakage will not exceed the maximum leak rate of 46 scfh which was the leakage assumed-in our LOCA radiological analyses. The calculated results are evaluated against the dose guidelines contained in 10 CFR Part 100 for offsite and 10 CFR:
Part 50, Appendix A, General Design Criteria (GDC) 19 for the control room.
The testing requirements for these valves are found in 10 CFR Part 50, Appendix J. " Primary Reactor Containment Leakage Testing for Water-Cooled 4
Power Reactors." The type C test requirements in Appendix J typically result in the valves being tested every refueling outage by local pressurization with air 223 psig, and the current TS limit per valve of 11.5 scfh.
f 9503270075 950322 PDR ADOCK 05000293 s
P POR
. A change is proposed to TS Section 4.7.A.2.a.4 to revise the acceptance criteria for allowable MSIV leakage from an individual valve leakage criteria to a maximum total combined main steam line leakage. The allowable leakage of 11.5 scfh per valve would be replaced with a maximum combined main steam line leakage of 46 scfh.
The proposed amendment results in no change in radiological consequences of the design basis LOCA as currently analyzed for PNPS.
These analyses were calculated using the combined total leakage factor of 46 scfh for determining acceptance to the regulatory limits for the offsite, control room, and Technical Support Center (TSC) doses as contained in 10 CFR Part 100 and 10 CFR Part 50, Appendix A, GDC 19. The proposed change does not compromise existing radiological equipment qualification, since the combined total leakage rate of 46 scfh has been factored into our existing equipment qualification analyses for 10 CFR 50.49.
There is no modification to the MSIVs or other plant system or structure associated with this amendment which could impact their capability to perform their design function. The total MSIV leakage rate of 46 scfh is included in the current radiological analyses for the assessment of dose exposure following an accident. This proposal changes the allowable leakage rate from a per valve to a total combined line leakage acceptance criteria but does not change the cumulative allowable value. The allowable leak rate limit specified for the MSIVs is used to quantify the maximum amount of bypass leakage assumed in the LOCA radiological analysis.
Results of the analysis are evaluated against the dose guidelines contained in GDC 19 and 10 CFR Part 100. The margin of safety in this context is considered to be the difference between the calculated dose exposures and the guidelines provided in GDC 19 and 10 CFR Part 100. Therefore, since the maximum allowable leakage for each valve was assumed and used as the total allowable leakage for the purpose of calculating potential dose, the margin of safety is not affected because the dose levels remain the same.
The proposed change does not change the radiological consequences of the design basis LOCA due to the fact that the maximum leakage rate remains the same. The current radiological analyses were calculated using the maximum leakage rate as the proposed change. This proposal changes the allowable leakage rate from a per valve rate to total combined line leakage acceptance criteria but does not change the cumulative allowable value.
Based on the facts as stated above, the NRC staff find this amendment change acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Massachusetts State official was notified of the proposed issuance of the amendment.
The State official had no comments.
1
i 6
e,
4.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC 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 i
proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (60 FR 3671). Accordingly, the 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 issuance of the amendment.
5.0 CONCLUSION
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 amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
K. Cotton Date:
March 22, 1995 i
.