ML20236N392
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i UNITED STATES NUCLEAR RECULATORY COMMISSIOll WASNINGTON. D.C. M1 September 10, 1997 MEMORANDUM T0.-
Jon Johnson. Director DivisionofReactorProjects.ReggnII FROM:
Gordon Edison. Acting Director i
Project Directorate Il-1 Division of Reactor Projects-I/II. NRR
SUBJECT:
CLOSURE OF TIA NO.97-006 REGARDING VESSEL DISASSEMBLY WITHOUT SECONDARY CONTAINMENT INTEGRITY ESTABLISHED -
BRUNSWICK STEAM ELECTRIC PLANT, UNIT 1 (TAC NO. M99043) 1.0 Introduction Over a 21-hour period beginning at 10:24 pm on October 6,1996. the reactor vessel head and steam dryer / separator assemblies were removed from the Brunswick Steam Electric Plant (BSEP). Unit 1. reactor vessel.
In TIA No.97-006. dated June 4. 1997, the Region 11 staff stated that, during the major portion of this disassembly, secondary containment integrity (SCI) was not established in that the standby gas treatment (SBGT) system was inoperable.
Region II has questioned the licensee's interpretation that such disassembly I
without SCI established is permitted by the unit's Technical Specifications (TS). The TIA requested that NRR provide assistance in determining the l
validity of the licensee's interpretation.
2.0 Discussion In the Operational Condition existing at the time on Unit 1 (Condition 5 -
refueling). TS 3.6.5.1 requires that SCI be maintained. Should SCI be lost in this condition. TS 3.6.5.1 recuires restoration of SCI within 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />s: or (Action b) suspension of irraciated fuel handling in the secondary containment. Core Alterations, and activities that could affect the Shutdown Margin.
Removal of the reactor vessel head and steam dryer / separator assemblies does not involve handling of irradiated fuel assemblies is not a Core Alteration, as defined in the BSEP TS. and is not an activity that could affect the Shutdown Margin. Thus the subject disassembly is not prohibited by TS 3.6.5.1 when SCI is lost.
The concern underlying this TIA is that the lifting of heavy loads directly above irradiated fuel in the vessel, at a time when SCI is not maintained, presents a potential for component drop and consequential fuel damage and unfiltered radioactivity release to the environment.
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In 1978. the NRC staff recognized the potential for load handling accidents and established Generic Activity Task A-36. " Control of Heavy Loads Near Spent Fuel" to examine the issue, and, in July 1980. NUREG-0612. " Control of Heavy Londs at Nuclear Power Plants." was issued. That document presented a defense-in-depth approach for controlling the handling of heavy loads including measures ranging from well-designed load handling systems to identification of safe load paths and personnel training. By Generic Letters (GLs) dated December 22. 1980. and February 3.1981, all licensees were requested to evaluate their plants against the guidance of NUREG-0612 in two phases. By GL 85-11. dated June 28. 1985, the staff stated that review of licensee Phase II evaluations was unnecessary because the staff had determined that Phase I implementation of guidelines provided sufficient protection such that the risk associated with potential heavy load drops is acceptably small.
In addition, at Brunswick, the licensee utilizes a reactor buildina crane that was upgraded in accordance with the guidelines contained in NUREG-1)612. No residual heavy loads handling concerns were identified of sufficient significance to demand further generic action. Both the NRC's May 18, 1984 Safety Evaluation (SE) concluding that Phase I implementation at BSEP was acceptable, and GL 85-11 indicate that the handling of heavy loads over the open reactor vessel during refueling was considered. The SE specifically addresses the vessel head and steam dryer / separator assemblies.
While the risk associated with these evolutions is acceptably small. it is not non-existent, and the licensee's actions on October 6 and 7,1996, did not reflect a conservative approach to plant operation. The fact that the TS action statement calls for sus >ension of fuel handling activities when SCI is lost should have highlighted tie desirability of maintaining SCI during the handling of heavy leads (fuel assemblies are considered a heavy load under NUREG-0612) in the vicinity of irradicted fuel. Maintenance of SCI during vessel disassembly is a logical extension of the defense-in-depth approacIl used in addressing the heavy loads issue and should be encouraged by the NRC.
3.0 Conclusion The removals of the reactor vessel head and steam dryer / separator assemblies from the Unit I reactor vessel on October 6 and 7.1996, without SCI established were not activities prohibited by TS 3.6.5.1.
The potential for load handling accidents is a safety question that has been.
reviewed by the NRC, and, given the actions taken by the licensee at BSEP relative to NUREG-0612. the associated risk is acceptably small.
Nonetheless, the licensee's actions in proceeding with vessel disassembly were not conservative, und Region 11 management should make this point with the L