ML14169A072
| ML14169A072 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear, FitzPatrick  |
| Issue date: | 06/19/2014 |
| From: | Entergy Operations |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| Download: ML14169A072 (61) | |
Text
Seismic Hazard Seismic Hazard Reevaluation Reevaluation June 19, 2014
IPEEE Questions Arkansas Nuclear One James A Fitzpatrick James A Fitzpatrick
Arkansas Nuclear One IPEEE Arkansas Nuclear One IPEEE W
th E
D/G F l
il t k
d 4160 Was the Emergency D/G Fuel oil tank and 4160 v Switchgear upgraded to 0.30 g?
E l i h th i
i i t b t ti Explain why there is some inconsistency between section 4.7 of the March submittal compared to RAIs from the IPEEE
Arkansas Nuclear One IPEEE Arkansas Nuclear One IPEEE W
th 4160 S it h d d t 0 30
?
Was the 4160 v Switchgear upgraded to 0.30 g?
4160 Volt Switchgear 2A-3 and 2A-4 4160 Volt Switchgear 2A 3 and 2A 4 Walk down performed during 2R12 outage 3rd set of plug welds observed versus 2 3
set of plug welds observed versus 2 Reevaluated with 3 sets of welds Switchgear HCLPF to >0 30 g Switchgear HCLPF to >0.30 g Documented in 96-SQ-2001-01 R. 0
Arkansas Nuclear One IPEEE Arkansas Nuclear One IPEEE Was the Emergency D/G Fuel oil tank upgraded to Was the Emergency D/G Fuel oil tank upgraded to 0.30 g?
Diesel Generator Fuel Oil Tank 2T-57A&B
- Re-evaluated
- Tanks qualified to 0.30 g
- Documented in 95-SQ-2521-01 revision 0
- Documented in GL 97-02 Completion Letter
Arkansas Nuclear One IPEEE Arkansas Nuclear One IPEEE Explain why there is some inconsistency p
y y
between section 4.7 of the March submittal compared to RAIs from the IPEEE.
f RAI Response A fault tree was constructed by removing the components not on the IPEEE safe shutdown list March submittal A fault tree was developed from the March submittal A fault tree was developed from the detailed plant fault tree, taking no credit for components on the IPEEE SSEL March submittal is in error ANO - Unit 1 IPEEE meets the requirements of Section 3.2.5.8 of NUREG-1407
J A Fitzpatrick IPEEE J.A. Fitzpatrick IPEEE How is the HCLPF calculation for the block walls in the IPEEE adequate?
How was relay chatter addressed?
W EPRI 6041 d f C t II SSC i th Was EPRI-6041 used for Category II SSCs in the Turbine Building?
J A Fitzpatrick IPEEE J.A. Fitzpatrick IPEEE How is the HCLPF calculation for the block How is the HCLPF calculation for the block walls in the IPEEE adequate?
NRC Bulletin 80-11 and A-46 walk-downs NRC Bulletin 80 11 and A 46 walk downs 3 walls subsequently installed 4
ll t
th d
4 walls strengthened EPRI NP-6041-SL Evaluating damping value used
J A Fitzpatrick IPEEE J.A. Fitzpatrick IPEEE How was relay chatter addressed?
How was relay chatter addressed?
Relay Chatter JAF was a Focused IPEEE 144 Outliers Outlier Seismic Verification Sheets (OSVS) form for each
(
)
outlier were filled out.
All outliers were resolved in 1998 However, SPID required new relay evaluation However, SPID required new relay evaluation JAF has committed to perform a new relay evaluation
J A Fitzpatrick IPEEE J.A. Fitzpatrick IPEEE W
bi Was EPRI-6041 used for Category II SSCs in Turbine Building?
YES Class I potions designed to both 0.08g for OBE and 0.15g for DBE DBE Class II portions governed by 0.08g design.
Class II OBE design controlling for preventing a collapse Class II OBE design controlling for preventing a collapse affecting Class I portions for DBE Table 2-3 of EPRI NP-6041 is applicable
Soil Properties Indian Point Energy Center
Indian Point Energy Center Indian Point Energy Center The new Ground Motion Response Spectra The new Ground Motion Response Spectra (GMRS) developed by EPRI and the NRC has some differences.
The source of the differences are the result of different properties assumed for the site amplification.
amplification.
EPRI used the historical hard rock values which would result in no amplification.
NRC used a softer rock value
Indian Point Energy Center Indian Point Energy Center Located west of the Hudson River in Buchanan, New York Th it h
th t
The site houses three reactors; Indian Point Unit No. 1 (SAFSTOR MODE)
Indian Point Units Nos 2 & 3 two Pressurized Indian Point Units Nos. 2 & 3, two Pressurized Water Reactors Site Area bedrock is rock of the Manhattan Formation, Limestone, and marble
Indian Point Energy Center Indian Point Energy Center The circa 1980 EPRI-SOG Summary Report indicates that the units were founded on basement rock with the site underlain by phillite y p and limestone Table 5-1 indicates hard limestone below 17 ft with a 7 ft layer of decomposed rock with a 7 ft layer of decomposed rock The regional rock units generally consist of gneiss, schist, granite, quartzite, and marble, all g
, g
, q typically associated with high Vs. (Shear Wave Velocity)
Indian Point Energy Center Indian Point Energy Center Building the three nuclear units required a Building the three nuclear units required a significant amount of rock removal.
Rock blasting was used to fragment and remove the rock to below foundation levels. Native rock elevations in the plant area varied from approximately Elev + 80 ft to Elev + 20 ft approximately Elev. + 80 ft. to Elev. + 20 ft.
towards the western part of the site.
Foundation elevations for the safety related ou da o e e a o s o e sa e y e a ed structures are, in general, 30 feet or more below grade/top of the rock. (final blasted elevation of rock)
Indian Point Energy Center Indian Point Energy Center There were no quantifications for the There were no quantifications for the compressional (p-wave) or shear wave velocities Estimates were based on information suggesting that, for the Indian Point site, shear wave velocities in excess of 9200 fps are appropriate NOTE 9200 FPS 2 804 16 NOTE: 9200 FPS = 2,804.16 mps
Indian Point Energy Center Typical Wave velocities
Indian Point Energy Center Indian Point Energy Center RECENT INFORMATION The 2010 and 2011 EPRI Reports relied upon the EPRI-SOG information The Indian Point Nuclear Generating Station site is considered a hard-rock site because the shear-wave velocity at the surface is > 9200 fps. This is consistent with the hard-rock ground motion equations used here for rock conditions (EPRI 2004) Therefore no site-for rock conditions (EPRI, 2004). Therefore, no site specific amplification calculations were made, and hard-rock hazard curves are used to determine the spectra.
Indian Point Energy Center Indian Point Energy Center RECENT EXCAVATION IN THE FUEL STORAGE BUILDING A single failure proof crane had to be installed A
h i
th i
d ti th k
Anchoring the crane required excavating the rock Rock removal:
No blasting allowed No blasting allowed Extremely difficult Numerous diamond drill bits were broken Rock samples were categorized as marble.
Indian Point Energy Center Indian Point Energy Center RECENT SOIL INVESTIGATIONS AT INDIAN POINT SITE 2005 thr 2007 POINT SITE 2005 thru 2007 Installation of groundwater monitoring wells Seismic Survey Work to facilitate movement of Spent Fuel Dry Work to facilitate movement of Spent Fuel Dry Casks Independent Spent Fuel Storage Installation of concrete pad
Indian Point Energy Center In 2006 a seismic survey was performed at a location Indian Point Energy Center In 2006 a seismic survey was performed at a location approximately 600 feet south of Indian Point 3 VC GPR measurements obtained depth to bedrock S i i
f ti t
di t i
l Seismic refraction surveys to predict compressional wave velocities in the fill and at the top of the rock Spectral Analysis of Surface Waves (SASW) data obtained using the ReMI Methods obtained using the ReMI Methods The rock profile in the area is highly fractured and is not representative of the rock characteristics in p
the plant area.
Fractures in rock result in reduced compressional and shear wave velocities and shear wave velocities
Indian Point Energy Center Indian Point Energy Center
Indian Point Energy Center Large discontinuities in the rock elevation.
Indian Point Energy Center g
AGS noticed several characteristics of the rock b
th th it Fi t th t
h f th beneath the site. First, the topography of the bedrock interface ranged from flat to highly variable over relatively short distances. There were a few y
locations where the bedrock interface disappeared and was located greater than 40-45 feet below ground surface(bgs) This occurred on Line 1 from ground surface(bgs). This occurred on Line 1 from stations minus10 to 40, and on Line 5 from stations 12 to 30.
Indian Point Energy Center Indian Point Energy Center
Indian Point Energy Center Indian Point Energy Center
Indian Point Energy Center (RQD) Rock Quality Designation is and Indian Point Energy Center (RQD) Rock Quality Designation is and indicator as to the degree of fragmentation in the rock Compare Monitoring Well logs along a line close to the southern part of the plant, i.e.,MWs-41,43,44,45,46, and 47 MWs 48 (and 40), which represent a line in the MWs 48 (and 40), which represent a line in the general area south of the Warehouse (where MW-48 is located).
Indian Point Energy Center Indian Point Energy Center MW RQD and Notes MW RQD 41 85 100 48 RQD values of 13, 23, and
- 58.
Fracture zone 41 85-100 43 73-100 44 80-100 Fracture zone Elev. 25 ft to Elev. 37-6 ft.
Fracture zone:
El 28 t 31 ft 45 97-100 46 68-100 47 95 100 40
- Elev. 28 to 31 ft
- Angular fragments Elev.
29.5 ft to 32 ft 47 95-100 40
- Elev. 35 ft to Elev. 38 ft.
- 35 ft to Elev. 37 ft Cl l
d f t
- Closely spaced fractures Elev. 71-4 to 71-9 ft.
Indian Point Energy Center Monitoring Well Map
Indian Point Energy Center Based on the significant fracturing in the MW Indian Point Energy Center Based on the significant fracturing in the MW closest to the seismic survey lines, it is apparent that the area suffered significant erosion and stress levels that caused significant rock fragmentation and discontinuities.
E ti t
t th l
iti f
Estimates as to the wave velocities away from this area of significant discontinuities should be used for Indian Point.
used o d a o
Indian Point Energy Center Indian Point Energy Center WORK PERFORMED BY GZA TO INSTALL MONITORING WELLS 23+ boreholes installed in the plant area Rock generally characterized as white MARBLE.
The Rock Quality Designation (RQD):
improves with depth improves with depth improves with distance away from the fragmentation caused by blasting and weathering generally in the 80 to 100 range P
f b d k f t
( hi h i l d t
f t
)
Presence of bedrock fractures (which includes transverse fractures) higher near the bedrock surface decreases with depth in the area of the Site The RQDs are affected by drilling techniques, core breakage during y
g q
g g
handling, stress-relief and air slaking, the presence of thinly bedded or closely jointed zone, and the extensive blasting at the site.
Attempts to correlate the RQDs with compressional or shear wave velocities would be questionable at best.
Indian Point Energy Center Indian Point Energy Center WORK PERFORMED BY TECTONIC AT THE FUEL STORAGE BUILDING BUILDING Eight borings were made inside the FSB and along the road to the FSB.
Four of the borings are in the FSB, just south of the Spent Fuel Pool Samples from borings B-1 and B-2 used to perform unconfined Samples from borings B-1 and B-2 used to perform unconfined compressive strength tests B-1 was taken at a depth of 9.5 to 10 B-2 was taken at a depth of 11 to 12 The RQDs at the sample locations were 66 and 55 respectively The RQDs at the sample locations were 66 and 55, respectively, indicating significant fragmentation effects from the adjacent blasting Results of the unconfined compressive strength testing on the two rock l
i ld d h
i f
i l 10 000 core samples yielded strength varying from approximately 10,000 to 20,000 pounds per square inch. These unconfined compressive strengths generally correlate to strong to very strong rock conditions.
Indian Point Energy Center Indian Point Energy Center WORK PERFORMED BY TECTONIC AT THE FUEL STORAGE BUILDING STORAGE BUILDING A seismic refraction study was performed along a 235 ft. long array along the road leading east from the FSB G h
l d fi (5) f t
t l
FSB. Geophones were placed five (5) feet apart along the array.
The Tectonic Report indicates that the rock quality p
q y
increases with depth.
The upper portion of the rock in this area is significantly fragmented as a result of the blasting for significantly fragmented as a result of the blasting for the FSB to the north and blasting for the Primary Auxiliary Building to the south.
Indian Point Energy Center Th P
l iti l
th t
f th k
f The P-wave velocities along the top of the rock vary from 12,500 fps to 13,900 fps.
Indian Point Energy Center Indian Point Energy Center WORK PERFORMED BY TECTONIC AT THE ISFSI PAD The ISFSI pad required the placement of a carefully engineered fill with properties that match carefully engineered fill with properties that match the ones used in performing the Dry Cask drop analyses.
y Up to five (5) feet of rock had to be removed to facilitate the placement of the engineered fill Rock removal was by mechanical means, significantly affecting the rock upper portion.
Indian Point Energy Center Indian Point Energy Center WORK PERFORMED BY TECTONIC AT THE ISFSI PAD Engineering Properties
Indian Point Energy Center Indian Point Energy Center WORK PERFORMED BY TECTONIC AT THE ISFSI PAD Seismic Refraction Arrays
Indian Point Energy Center Indian Point Energy Center WORK PERFORMED BY TECTONIC AT THE ISFSI PAD PAD Included the characterization of the underlying rock y g Included seismic refraction studies along six (6) arrays Results from the seismic refraction work were used to Results from the seismic refraction work were used to verify the predictions as to depth to bedrock Some anomalies existed with the sixth array Estimates as to the compressional wave velocities obtained from the Line 6 array should not be considered
Indian Point Energy Center Indian Point Energy Center SEISMIC REFRACTION Estimates the rock compressional wave velocities along the interface between the engineered fill along the interface between the engineered fill and the top of the rock The top of the rock layer is weathered and more f
t d fragmented Measured compressional wave velocities along weathered rock surface do not represent the weathered rock surface do not represent the wave velocities at a depth in the range of 30 ft.
below the top of the rock
Indian Point Energy Center Indian Point Energy Center The mean of the low bound compressional wave velocities from The mean of the low bound compressional wave velocities from Arrays 1 through Array 6 is 13,217 fps.
The mean of the upper bound compressional wave velocities from Arrays 1 through Array 6 is 15,633 fps.
The overall mean of the compressional wave velocities measured at the ISFSI pad for the rock upper portion is 14,425 fps.
Fractures, more prevalent in the upper portions of the rock, result Fractures, more prevalent in the upper portions of the rock, result in a reduction in the compressional (Vp) and shear wave (Vs) velocities through the rock Velocities measured by Tectonic represent compressional wave velocities through fractured and weathered rock in the top velocities through fractured and weathered rock in the top section of the rock and do not represent wave velocities representative of locations 30 feet below the rock surface.
Indian Point Energy Center Indian Point Energy Center Tectonic observed that: The presence of bedrock fractures Tectonic observed that: The presence of bedrock fractures (which includes transverse fractures) is reported to be higher near the bedrock surface and to decrease with depth in the area of the Site (Tectonic, 2004).
Based on the above observations it may be inferred that the Based on the above observations, it may be inferred that the wave velocities measured by Tectonic represent reduced compressional wave velocities through fractured rock and that at depths of 30 ft. or more below the rock surface, the improved rock quality results in higher wave velocities rock quality results in higher wave velocities.
For the purpose of estimating compressional wave velocities away from the fractured, and weathered, rock surface, we shall assume the compressional wave velocity at the foundation level f
f f
of safety related structures is equal to the mean value of the wave velocities for the ISFSI arrays, i.e. Vp = 14,425 fps.
Indian Point Energy Center Indian Point Energy Center CONCLUSION The site sits on hard rock historic documents it ti k
site excavation work applicable well data Use of selective site data is inappropriate Use of selective site data is inappropriate perimeter well data ISFS Pad surface data ISFS Pad surface data
Seismic Screening Indian Point Energy Center
Indian Point Energy Center Indian Point Energy Center IP3 was screened in as a Priority 1 plant for an SPRA since the consideration of the more recent re-assessment of the IPEEE was not considered.
The original IPEEE analysis in 1995 was performed to meet the minimum Review Level Earthquake (RLE).
The actual capacity of the plant is much higher.
Demonstrated in recent re-assessment of IPEEE
Indian Point Energy Center Indian Point Energy Center In 2010/2011 the NRC used values for plant p
capacity extracted from the IP3 IPEEE report submitted in 1997.
This resulted in the NRC determining a very conservative SCDF estimate of 1.0E-04 per year, or 1 in 10,000 reactor-years.
1 in 10,000 reactor years.
NRC has evaluated and stated any plant with a SCDF value lower than 1.0E-04 per year (or 1 in 10 000 t
) i t bl 10,000 reactor-years) is acceptable.
Indian Point Energy Center Indian Point Energy Center Using the improved plant capacities developed by a Seismic review team a reassessment of the SCDF estimate was performed in April 2011.
This report IP-RPT-11-00012 (ML13183A280) was transmitted to the NRC by June 2013 letter NL-13-084 (ML13183A279).
With the use of the improved plant capacities and EPRI updated 2010 hazard curves; EPRI updated 2010 hazard curves; A new SCDF was estimated at 7.1E-06 per year (or 1 in 140,845 reactor-years).
Indian Point Energy Center Indian Point Energy Center Assessment Approach Understanding the current seismic risk to the station, in terms of SCDF.
Identifying potential conservatisms within the IP3 Identifying potential conservatisms within the IP3 IPEEE submittal information used by the NRC in the SCDF calculation.
Making IPEEE component fragility values more realistic.
The team computed fragility values for a sample The team computed fragility values for a sample of components that are high contributors to risk using original component design documents
Indian Point Energy Center Indian Point Energy Center Reducing conservatism in the USGS seismic g
Hazard Curves.
the USGS seismic hazard calculations did not include Cumulative Absolute Velocity (CAV) filtering and ground Cumulative Absolute Velocity (CAV) filtering and ground motion incoherence, which tend to reduce the acceleration values.
Developing a more realistic SCDF using the revised Developing a more realistic SCDF using the revised fragilities and hazard curves.
It should be noted that the original PRA computer model S i i H d I t ti P
(SHIP) i t
il bl Seismic Hazard Integration Program (SHIP) is not available to be modified and an alternate approach was developed
Indian Point Energy Center Indian Point Energy Center Identification of Low Capacity Components in dominant sequences Seismic-induced loss-of-offsite power (LOSP) and the subsequent loss of on site AC power from all the subsequent loss of on-site AC power from all three emergency diesel generators.
Loss of secondary side cooling due to depletion of the condensate storage tank and failure of RHR shutdown cooling due to the seismic event.
Loss of component cooling water (CCW) or Loss of component cooling water (CCW) or containment fan coolers due to a seismic event.
Indian Point Energy Center Indian Point Energy Center
Indian Point Energy Center Indian Point Energy Center The improved values for the median capacity (Am = 1.27g),
and composite uncertainty (
0 4) calculated by the and composite uncertainty (c = 0.4) calculated by the review team resulted in a SCDF estimate of 9.4E-06 per year (1 in 106,383 reactor-years) associated with the t USGS H d C hi h t
current USGS Hazard Curves which represents a significant reduction from the GI-199 reported SCDF estimate (1.0E-04 per year or 1 in 10,000 reactor-years) d i h
li i i
f h i
i i k and is a much more realistic estimate of the seismic risk.
It should also be noted that using the improved fragility (Am
= 1.27g, and c = 0.4 ) along with the 2010 EPRI updated g,
c
)
g p
seismic Hazard Curves instead of the USGS curves further reduces the SCDF value to 7.1E-06 per year (or 1 in 140,845 reactor-years) y
)
Indian Point Energy Center Indian Point Energy Center The IPEEE and its reassessment were reviewed for adequacy utilizing the guidance provided in Section 3 3 of adequacy utilizing the guidance provided in Section 3.3 of the SPID (EPRI, 2013a). A detailed description of the results of the IPEEE adequacy review is included in A
di B f th M
h S b itt l (ML14099A111)
Appendix B of the March Submittal (ML14099A111).
The results of these reviews have shown, in accordance with the criteria established in SPID (EPRI, 2013a) Section 3.3, that the IPEEE and reassessment of the IHS are adequate to support screening of the updated seismic hazard for Indian Point Unit 3. The review also concluded that the risk insights obtained from the IPEEE are still valid under the current plant configuration.
Indian Point Energy Center Indian Point Energy Center Scaling the Review level earthquake (RLE)
Am = 0.975g c = 0.30 HCLPF = Am x e - (2.3264 x c ) = 0.975 x e - (2.3264 x 0.30 )
m
= 0.975 x 0.4976 = 0.485g Scaling factor Scaling factor 0.485/0.23 = 2.11
Indian Point Energy Center Indian Point Energy Center Conclusion Based on the results of the screening evaluation, I di P i t U it 3 t
f i k Indian Point Unit 3 screens-out of a risk evaluation.
Unit 2 will perform its SPRA in group 1 and Unit 2 will perform its SPRA in group 1 and should show adequate margin based on initial results from Unit 3.
SUMMARY
SUMMARY
Ensure a complete understanding of the NRC ti questions.
IPEC is a hard rock site.
IP3 Updated IPEEE should be used to evaluate the IP3 Updated IPEEE should be used to evaluate the new GRMS.
IP3 should be screened out of an additional risk assessment since it has already been performed.
Additional confirmation of safety provided by ESEP.
If dditi l ti i
d d t i
th IPEEE IP3 If additional time is needed to review the IPEEE IP3 should be categorized as a Conditional Priority 3 plant.
p