IR 05000263/1996009
| ML20217F281 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 04/20/1998 |
| From: | Beach A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Wadley M NORTHERN STATES POWER CO. |
| References | |
| 50-263-96-09, 50-263-96-9, 50-263-97-10, NUDOCS 9804280116 | |
| Download: ML20217F281 (4) | |
Text
April 20, 1998
SUBJECT:
EXERCISE OF ENFORCEMENT DISCRETION (NRC Inspection Reports 50-263/96009(DRS) and 50-263/97010(DRS))
Dear Mr. Wadley:
The NRC conducted two special team inspections at Northem States Power Company's (NSP)
Monticello Nuclear Generating Plant from November 1996 through June 1997. The inspections identified apparent violations of 10 CFR 50.59, " Changes, test, and Experiments," associated with residual heat removal (RHR) and RHR service water (RHRSW) pump requirements and the uss of containment overpressure in emergency core cooling system pump performance calculations. The results of these inspection were discussed with NSP staff members on January 8 and June 27,1997. A predecisional enforcement conference was held in the Region 111 office on March 3,1997, to discuss the apparent violation of 10 CFR 50.59 associated with the RHR and RHRSW pump requirements.
Based on the information developed during the inspections and the information that the NSP staff provided during the predecisional enforcement conference, the NRC has determined that two violations of NRC requirements occurred. These violations are described below and the circumstances surrounding them are described in detail in the subject inspection reports.
The first violation pertains to the number of RHR and RHRSW pumps required for containment cooling. Prior to 1987, the final safety analysis report (FSAR) stated that a worst-case scenario was the availability of only one RHR pump and one RHRSW pump for containment cooling.
This was based on the emergency diesel generator design which could load only one RHR and one RHRSW pump. Subsequent to containment modifications, the FSAR was revised in 1987 to state that two RHR pumps and two RHRSW pumps were required during the long-term post-accident cooldown phase. The licensee identified, in 1992, that the FSAR incorrectly stated the loads that the emergency diesel generator could maintain. Subsequent to this identification, NSP updated the safety analysis to verify adequate long term containment heat removal and corrected the FSAR to state that a worst-case scenario was the availability of only one RHR pump and one RHRSW pump for containment cooling. In 1997, the NRC questioned the adequacy of the safety evaluation used to facilitate the FSAR change and conducted a predecisional enforcement conference to discuss potential deficiencies in NSP's 10 CFR 50.59 process. Subsequent to the conference, the NRC determined that the violation was caused by N O deficiencies in the design change proass that was in place in 1987 and not a failure of NSP's d@
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, CFR 50.5g process. The failure of NSP's design change process to maintain the design of a system required to mitigate a serious safety event is a violation of NRC requirements.
. Accordingly, this violation is classified in accordance with NUREG-1600, " General Statement of Policy and Procedure for NRC Enforcement Actions (Enforcement Policy)," as a Severity Levellli violation.
The second issue pertains to the acceptability of using containment overpressure in determining whether adequate net positive suction head was available for the emergency core cooling system pumps following a design basis loss of coolant accident. As documented in inspection Report 50-263/97010, the NRC determined that NSP had not been granted permission to use containment overpressure and that the increased dependence upon containment overpressure to ensure adequate net positive suction head constituted an unreviewed safety question. The failure to identify an unreviewed safety question constitutes a violation of 10 CFR 50.59 such that the licensee did not identify that a license amendment was required prior to implementation of the change to increase the dependency upon containment overpressure. Accordingly, this violation is classified in accordance with the Enforcement Policy
as a Severity Levellil violation.
l in accordance with the Enforcement Policy, civil penalties would normally be considered for each Severity Level lli violation. A civil penalty was considered in this case because these l
violations demonstrated that the management control systems were not adequate to maintain
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system design or that unreviewed safety questions were identified and resolved. However, I have been authorized after consultation with the Director, Office of Enforcement, to exercise enforcement discretion in accordance with section Vll.B(6) of the Enforcement Policy and not propose a civil penalty or issue a notice of violation in this case. Discretion was warranted because (1) the design change violation was identified by NSP during a voluntasy initiative; (2) for the 10 CFR 50.59 violation: (a) the FSAR and accompanying NRC safety evaluation report did not explicitly discuss the net positive suction head requirements for the pumps; (b) the condition was subtle in nature and not likely to be disclosed through routine surveillance or quality assurance activities; and (c) the NRC identified a generic concem regarding use of containment overpressure; (3) the corrective actions, both taken and planned for both issues, were comprehensive and timely; (4) neither violation was willful; and (5) neither violation would be categorized at a severity level higher than Severity Level 11.
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NSP is not required to respond to this letter. In accordance with 10 CFR 2.790 of the NRC's
" Rules of Practice," a copy of this letter will be placed in the NRC Public Document Room.
Sincerely, ft
uend
.u Bill Beach Regional Administrator Docket No.: 50-263 cc w/ encl:
Plant Manager, Monticello State Liaison Officer, State of Minnesota
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. DISTRIBUTION:
PUBLIC IE-01 SECY CA LCallan, EDO AThadani, DEDE LChandler, OGC JGoldberg, OGC SCollins, NRR RZimmerman, NRR
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Enforcement Coordinators RI, Rll and RIV Resident inspector, Monticello JHannon, NRR TKim, NRR -
JGilliland, OPA HBell, OlG GCaputo,01 TMartin, AEOD OE:ES -
OE:EA(2)
RAO: Rill SLO: Rill PAO: Rill OCFO/LFARB w/o encl.
DRP Docket Filo