ML18102A144
| ML18102A144 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 05/29/1996 |
| From: | Eric Simpson Public Service Enterprise Group |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LR-N96147, NUDOCS 9606030258 | |
| Download: ML18102A144 (6) | |
Text
j E. C. Simpson Senior Vice President - Nuclear Engineering Public Service
- Electric and Gas Company Public Service Electric and Gas Company P.O. Box 236, Hancocks Bridge, NJ 08038 609-339-1700 MAY 2 9 1996 LR-N96147 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen
SALEM FUEL HANDLING BUILDING VENTILATION SYSTEM SALEM GENERATING STATION, UNIT NO. 2 DOCKET NO. 50-311 On May 23 and 24, 1996, representatives from Region I and Public Service Electric and Gas (PSE&G) met to discuss the results of the Salem Design and Licensing Basis Conformance Inspection conducted between May 6 and 17, 1996.
Those discussions served to clarify and focus the outstanding issues relating to the design and licensing basis of the Fuel Handling Building Ventilation (FHV) system. The remaining issues relate to interpretation of information provided during the licensing process and its relationship to NRC regulatory requirements in effect at that time.
Our present schedule for restart of Salem Unit 2 calls for spent fuel movement within the very near future.
PSE&G believes that this evolution can be completed safely with the present system design.
The safety implications associated with this activity have been assessed, and a 50.59 safety evaluation is being prepared.
The safety evaluation will require the system to be placed in the accident mode alignment, with the HEPA and HEPA/Charcoal filter train dampers blocked in the appropriate positions.
This will preclude the majority of potential single failures which could cause an unfiltered release.
The evaluation also credits operator response to trip the supply fan in the unlikely event of an exhaust fan trip.
This action provides protection against the potential for unmonitored releases from the fuel handling building.
Any deviation from the above will result in termination of fuel handling activities.
The Fuel Handling Accident has been reanalyzed to model present plant conditions.
This analysis credits the actual decay time available for the worst case fuel bundle, takes no credit for charcoal filtration and uses Safety Guide 25 methods and standard assumptions to calculate accident releases and associated doses.
The resultant doses are extremely small fractions of the 10 CFR 100 acceptance criteria and within General Design Criterion 19
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Document Control Desk LR-N96147 2
MAY 2 9 1996 The following information is provided in response to the specific issues identified during the meeting of May 24, 1996.
- 1)
PSE&G has been unsuccessful at locating the original licensing basis calculations for the Fuel Handling Accident.
To date, the only information available regarding the original analysis is the summary information which was presented in Section 14.4.4 of the original Salem Final Safety Analysis Report.
PSE&G submitted to the NRC plant specific calculations for the Fuel Handling Accident in support of the spent fuel pool rerack projects which were recently completed at Salem Units 1 and 2.
These calculations constitute the current licensing basis for the Fuel Handling Accident analysis.
Conformance with the assumptions utilized in these calculations will be verified before declaring the FHV system operable.
PSE&G has identified two potential non-conservative assumptions associated with the Fuel Handling Accident analysis referenced above.
The assumed decontamination factor of 500 for spent fuel pool iodine removal and the charcoal filter efficiencies of 99% for iodine removal are inconsistent with Safety Guide 25 standard assumptions.
Revised calculations are being prepared which use the Safety Guide 25 values for these parameters.
Preliminary indication is that the results are higher than those derived by the NRC in the Safety Evaluation supporting License Amendments 131 and 151, but remain very small fractions of the 10CFR100 limits and also satisfy GDC 19 control room dose requirements as well.
The reasons for the higher doses is under investigation at this time.
- 2)
Two exhaust fans and one supply fan are required to be in service with an available filtration flow path (i.e.,
dampers and duct work), to meet Technical Specification operability requirements.
This configuration represents the as tested configuration under the Technical Specification surveillance requirements.
Failure to meet the above configuration will result in the suspension of all load handling or fuel movement activities in or over the spent fuel pool.
Document Control Desk LR-N96147 3
MAY 2 9 1996 Appropriate Operations Department guidance (i.e., operating procedures, alarm response procedures) will be reviewed to assure compliance with these requirements.
- 3)
The values currently reflected in the Salem Updated Final Safety Analysis Report (UFSAR) represent the range of temperatures required for normal occupancy of the Fuel Handling Building.
Conditions required for operability of equipment within the building have been assessed for a lower limit of 40°F.
A qualitative assessment supports an upper limit for equipment qualification at 120°F.
Until equipment qualification at this level is confirmed, 105°F will be considered as the upper limit for equipment operability.
Appropriate administrative controls will be established to ensure that building temperature is monitored if ambient conditions indicate that the 105°F limit will be challenged.
Following completion of the equipment qualification review, appropriate clarifications will be made to the UFSAR.
A confirmatory review of supporting calculations will be completed to assure that the system is capable of providing required heating and cooling capability.
This review will verify that the FHV system, as designed, can maintain room temperatures within the 60° to 105°F limits specified for system performance.
- 4)
The statement in the Final Safety Analysis Report (FSAR) and the present UFSAR regarding the ability of the system to withstand single active failures is not supported by the design of the FHV system.
PSE&G is developing a failure analysis for the FHV system to determine if modifications should be made to improve the overall defense in depth associated with this design.
In the interim, our operating alignment will be modified during fuel movement to align flow through the charcoal filter train.
Appropriate dampers will be blocked in their fail-safe positions.
These measures will preclude the majority of potential single failures within the FHV system.
As mentioned previously, operator action will be credited for tripping the supply fan in the event of an exhaust fan trip.
This is acceptable based on our calculations which show that 10CFRlOO and GDC 19 acceptance criteria are met for present plant conditions, assuming an unfiltered release during the Fuel Handling Accident.
Document Control Desk LR-N96147 4
MAY 2 9 1996 PSE&G has conducted a review of the licensing history surrounding the FHV to assess whether any NRC regulations have been violated.
To date, PSE&G has identified no explicit NRC requirement in effect at the time of licensing that would have required a single failure tolerant design for the FHV system.
While the General Design Criteria (GDC) contained in 10CFR50 Appendix A generally invokes the single failure criterion, at the time the Salem units were licensed, application of the single failure criteria was focussed on those systems required to mitigate the consequences of reactor accidents.
This is reinforced by the scoping statements contained in Proposed IEEE Criteria for Nuclear Power Plant Protection Systems, IEEE 279, 1968 and 1971 versions.
Section VI of the GDC, Fuel and Radioactivity Control, ( 1971 version) includes those requirements applicable to the design of FHV systems, none of which specifically invoke the single failure criterion.
Much of the NRC's design guidance, including the GDC and Regulatory Guides, evolved after the issuance of the construction permit for the Salem units.
While comparisons were made to this evolving guidance, they were not exhaustive design reviews and as such did not capture all exceptions to NRC guidance.
Early NRC guidance contained in Safety Guide 13 and subsequently Regulatory Guide(R.G.) 1.13 (Revision 1 Draft), relates to design of FHV systems but does not invoke the single failure criterion.
Regulatory Guide 1.52, Revision 1, was issued about the time Salem Unit 1 was originally licensed, relates to design and testing of ESF Ventilation Systems and does discuss redundancy within the design of these systems.
PSE&G took exception to the redundancy provisions of R.G. 1.52 for secondary ventilation systems, i.e., the FHV system.
- 5)
Inadequate charcoal filter bypass leakage testing was a self-identified condition prior to the NRC inspection and has been addressed through improvements to the test methodology.
Testing of charcoal filter bypass leakage has been completed and is within the limits of the Technical Specifications. Additionally, all required surveillance testing will be verified current prior to declaring the system operable.
Document Control Desk LR-N96147 5
MAY 2 9 1996
- 6)
The high vibration condition on the FHV exhaust fans was also a self-identified condition prior to the inspection.
Vibration data taken since identification continues to support operability of the fans.
The vibration is higher than desirable and monitoring frequencies are consistent with the level of vibration noted.
The 21 fan is monitored monthly and the 22 fan is monitored weekly.
Test results are reviewed immediately following the test by the test engineer and the system engineer.
Indication of a degrading condition will be reported to the Senior Nuclear Shift Supervisor with a recommendation to remove the equipment from service.
Repair parts have been procured and are onsite, with repairs expected to be completed in July of 1996.
- 7)
A Design Change Package to provide auto-start capability upon receipt of a high radiation signal has been prepared.
Field implementation will occur during the week of May 27, 1996.
Operability will be verified in accordance with appropriate Technical Specification requirements.
- 8)
PSE&G has reviewed the UFSAR discussion and has completed preliminary calculations to assure that there is no technical or safety concern associated with charcoal heat loading during accident conditions.
These calculations show that a heat generation rate on the order of two hundred thousand BTU/Hr is required before deabsorption would occur.
To reach the charcoal ignition point, additional heating would be required.
Based on the assumption that all available decay energy is converted to heat PSE&G calculates a heat generation rate of 25 BTU/Hr.
Appropriate revisions to the UFSAR will be made to clarify this item.
PSE&G agrees that the licensing basis documentation for the FHV system requires clarification.
PSE&G will prepare a revised description for the UFSAR when all issues are brought to closure.
This update would then be incorporated at the next regularly scheduled UFSAR update.
Document Control Desk LR-N96147 MAY 2 9 1996 6
If you have any questions regarding the attached, please feel free to contact me.
Sincerely, C
Mr. T. T. Martin, Administrator - Region I U. S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Mr. L. N. Olshan, Licensing Project Manager - Salem U. S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 14E21 Rockville, MD 20852 Mr. C. Marschall (X24)
USNRC Senior Resident Inspector Mr. K. Tosch, Manager, IV Bureau of Nuclear Engineering 33 Arctic Parkway CN 415 Trenton, NJ 08625
.