ML20217B231
| ML20217B231 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 09/11/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20217B228 | List: |
| References | |
| NUDOCS 9709230275 | |
| Download: ML20217B231 (3) | |
Text
_ _ _ - _ _ _ _ - _ _ _ _ - _ - - _ - _ _ - - - - - - - - - - - - -
A"4 9 l
p
- a UNITED STATES l
g
}
NUCLEAR REGULATORY COMMISSION p.....j$
WASHINGTON, D.C. 90666-0001 SAFETY EVALUATION BY 1HE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS. 200 AND 184 TO FACILITY OPERATING LICENSE NOS. DPR-70 AND DPR-75 PUBLIC SERVICE ELECTRIC & GAS COMPANY PHILADELPHIA ELECTRIC COMPANY 9
DELMARVA POWER AND LIGHT COMPANY g
(
ATLANTIC CITY ELECTRIC COMPANY SALEM NUCLEAR GENERATING STATION. UNIT NOS. 1 AND 2 DOCKET NOS. 50-272 AND 50-311 3
1.0 INTRODUCTION
By [[letter::LR-N970256, Application for Amends to Licenses DPR-70 & DPR-75, Eliminating Flow Path from RHR Sys to RCS Hot Legs as Specified in LCO 3.5.2.c.2|letter dated April 25, 1997]], as supplemented on June 6, 1997, the Public Sarvice Electric & Gas Company (the licensee) submitted a request for changes to the Salem Nuclear Generating Station, Unit Nos.1 and 2, Technical Specifications (TSs). These amendments change TS 3.5.2, "ECCS Subsystems -
T,, it 350*F," to eliminate the flw path from the residual heat removal syr.em to the reactor coolant system hot legs. This flow path is being eliminated to prevent excessive flow through the residual heat removal system during all hot leg recirculation configurations assuming worst-case single failures that could result in increased flows following a loss-of-coolant accident (LOCA) during hot leg recirculation.
The licer.see's supplemental letter provided additional information that clarified the information in the original submittal. The supplemental letter alsL corrected an error that was included in the original Federal Reaister notification (62 FR 26574). Specifically, the licensee referred to the enthalpy of saturated steam at 25 psig as 1160.1 British Thermal Units / Pound-mass (BTU /lbm) and the enthalpy of saturated liquid at 25 psig as 208.52 BTU /lbm. The correct values are 1169.6' BTU /lbm and 235.68 BTV/lbm, respectively. This error wi.s insignificant. and did not affect the staff's original proposed no significant hazards consideration determination.
2.0 BACKGROUND
In 1994, Westir.ghouse (the licensee's nuclear steam supply system vendor) informed the licensee that a high residual heat removal (RHR) pump flow condition can occur during the hot leg recirculation phase of a LOCA.
Specifically, failure of one RHR pump would cause the operatii.g pump to supply the suction flow to the intermediate and high head safety injection pumps and 9709230275 970911 PDR ADOCK 05')O0272 P
' also the flow to the low head hot leg injection flow path either directly or the result of a loop-around flow path. The licensee deternined that the resultant flow may have resulted in the remaining RHR > ump operating beyond its actual run-out limit which could have challenged tie operation of the
]
pump.
To eliminate this potential problem, in 1934 the licensee changed the emergency operating procedures (EOPs) to eliminate the procedure steps associated with opening the RHR hot leg injection path (via valve RH26). The elimination of this fitw path reduced the amount of flow delivered by the RHR pumps during hot leg recirculation to ensure adequate margin for the RHR pumps during the hot leg recirculation phase of a LOCA.
However, TS 3.5.2.c. states that RHR will discharge into the two reactor coolant system hot legs durin.) the recirculation phase.
Since, the licensee no longer directly injects into the hot legs through the RHR system Guring hot leg recirculation, the licensee is proposing a TS change to remove the reference to RHR hot leg injection.
3.0 EVALUATION l
The licensee's design basis for the emergency core cooling systems is contained in UFSAR Section 6.3.1.
This section states, in part, that the system "is designed to tolerate a single active failure during the short-term immediately following an accident, or to tolerate a single active or passive l
failure during the long-term following an accident." This design basis l
requirement is consistent with the requirements of General Design Criterion 35, " Emergency Core Cooling," and Apper. dix K to 10 CFR hrt 50 "ECCS Evaluation Models."
The RHR hot leg recirculation phase therefore is required to tolerate a single active or passive failure. As discovered by the licensee in 1994, the system was vulnerable to a single failure and thus did not meet the design basis requirement. The licensee changed it: emergency operating procedures and Updated Final Safety Analysis Report to reflect a revised mode of operation that would prevent the possibility of excessive RHR flow assuming a single failure. Additionally, Post LOCA not leg recirculation ensures that no boron precipitation occurs in the reactor vessel as a result of boiling and consequential boron concentration. The licensee verified that the high head and intermediate head safety injection flows provide adequate hot and cold leg flow after initiation of hot leg recirculation to prevent an increase of core boron concentration. The staff has reviewed the licensee's revised RHR hot leg recirculation and finds it acceptable since it restores compliance with the design basis single failure tolerance requirement.
The licensee-is proposing to change the TS to delete reference to manually initiating discharge into the two reactor coolant system hot legs by the RHR pumps. The licensee is requesting this change to remove a statement that could be interpreted to require that the RHR pumps inject directly into the hot legs (due to the.1994 procedure changes the RHR pumps inject into the hot s
n
- legs indirectly by feeding the intermediate nead safety injection pumps).
The licensee's proposed TS revision clarifies the TS by removing a statement that is subject to interpretation.
The ca) ability of the RHR system to inject into the reactor coolant system hot legs tirough the safety injection pumps is adequately covered in TS 3.5.2.b which requires that the safety injection pumps be able to discharge into the associated reactor coolant system hot legs by using the RHR ) ump discharge piping. Therefore, the licensee's proposed TS change is accepta)le.
The staff notes that the change presented above does not eliminate the requirement to maintain the flow path through RH26. The hot leg injection flow path through RH26 is still required for mitigating Mode 4 LOCAs.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the New Jersey State official was notified of the proposed issuance of the amendments.
The State official had no commer'3.
5.0 {NVIRONMENTAL CONSIDERATION The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. 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 consideration, and there has been no public comment on such finding (62 FR 26574). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.2 '(c)(9).
Pursuant to 10 CFR 51.22 environmental assessment need be prepar(b) no environmental impact statement or ed in connection with the issuance of the amendments.
6.0 CONCLUSION
The Commission has concluded, based on the consideraticas 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, end (3) the issuance of the amendments will not be inimical to the common defense and security or to the healta and safety of the public.
Principal Contributor:
S. Dembek Date:
September 11, 1997
._d