IR 05000397/1998001
| ML17292B441 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 09/21/1998 |
| From: | Merschoff E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Parrish J WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| References | |
| 50-397-98-01, 50-397-98-1, EA-98-228, NUDOCS 9809250230 | |
| Download: ML17292B441 (28) | |
Text
September 21, 1998
SUBJECT:
RESULTS OF NRC'S ENFORCEMENT DELIBERATIONS (NRC INSPECTION REPORT 50-397/98-01)
Dear Mr. Parrish:
This refers to the predecisional enforcement conference attended by representatives of the Washington Public Power Supply System (Supply System) on July 13, 1998, in the NRC's Arlington,'Texas, office. The conference was conducted to discuss an apparent violation of design control requirements at the Washington Nuclear Project-2 (WNP-2), in tnat, it'appeared that the Supply System had not exercised adequate control over its fuel vendor's development of operating and safety limits for fuel used in WNP-2 Core Cycles 7-12. The apparent violation was described in the NRC's Inspection Report 50-397/98-01 issued May 8, 1998.
The Supply System's position on the apparent violation, as discussed in detail at the conference and in the Supply System's July 9, 1998, letter to the NRC, is that the data used to derive the operating and safety limits for the fuel actually. used in WNP-2 (SPC 9x9-9x) was adequate because this fuel did not utilize a ULTRAFLOWspacer.
Your staff also argued that oversight of your fuel vendor was adequate, and that the vendor's development of operating and safety limits for fuel used in Core Cycles 7-12 was consistent with NRC-approved methodologies (Advanced Nuclear Fuel Topical Report ANF-1125-PA). Therefore, the Supply System disagreed that a violation had occurred.
In addition, your staff noted that it had taken corrective action to adopt more conservative operating limits in response to NRC concerns.
Based on a review of all available information, and in particular the information provided at the conference, the NRC has determined that there was no violation of NRC requirements in this case.
Despite NRC's concern over the fuel vendor's use of a limited number of data points in deriving uncertainty values, which the NRC believes resulted in nonconservative limits, the NRC agrees fundamentally with the Supply System's position that those efforts were consistent with NRC-approved guidance documents.
In that the NRC is satisfied with the corrective actions taken by the Supply System, the NRC does not believe that this matter warrants further evaluation.
.
In accordance with 10 CFR 2.790 of the NRC's Rules of Practice, a copy of this letter and enclosure will be placed in the NRC Public Document Room.
9809250230 98092'DR ADCICK 05000397
0
Washington Public Power Supply System-2-Should you have any questions about this matter, we willbe pleased to discuss them with you.
Sincerely, Docket No. 50-397 License No. NPF-21 Ellis
. Merschoff Regional Administrator Enclosure:
Licensee Conference Handout cc w/Enclosure:
Chairman Energy Facility Site Evaluation Council P.O. Box 43172 Olympia, Washington 98504-3172 Mr. Rodney L. Webring (Mail Drop PE08)
Vice President, Operations Support/PIO Washington Public Power Supply System P.O. Box 968 Richland, Washington 99352-0968 Mr. Greg O. Smith (Mail Drop 927M)
WNP-2 Plant General Manager Washington Public Power Supply System P.O. Box 968 Richland, Washington 99352-0968 Mr. D. W. Coleman (Mail Drop PE20)
Manager, Regulatory Affairs Washington Public Power Supply System P.O. Box 968 Richland, Washington 99352-0968 Mr. Albert E. Mouncer (Mail Drop 396)
Chief Counsel Washington Public Power Supply System P.O. Box 968 Richland, Washington 99352-0968
e
Washington Public Power Supply System-3-Mr. Paul Inserra (Mail Drop PE20)
Manager, Licensing Washington Public Power Supply System P.O. Box 968 Richland, Washington 99352-0968 Perry D. Robinson, Esq.
Winston 8 Strawn 1400 L Street, N.W.
Washington, D.C. 20005-3502
0
Washington Public Power Supply System-4-bcc to DCD (IE01)
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Regional Administrator Resident Inspector DRP Director DRS-PSB Branch Chief (DRP/E, WCFO)
MIS System Senior Project Inspector (DRP/E, WCFO)
RIV File Branch Chief (DRP/TSS)
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Regional Administrator Resident Inspector DRP Director DRS-PSB Branch Chief (DRP/E, WCFO)
MIS System Senior Project Inspector (DRP/E, WCFO)
RIV File Branch Chief (DRP/TSS)
ACES:EAFile OE:EAFile OE:Director DOCUMENT NAME: G:'tREPORTS>EA98228.WPD To receive copy of document, indicate in box: 'C'
Cop without enclosures 'E'Cop wit en losures 'N'
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Washington Public Power Supply System NRC Enforcement Conference July 13, 1998,
Agenda Introduction Restatement ofIssue Fuel Design Considerations Safety Signi6cance Vendor Oversight Program Regulatory Perspective Paul Bemis Roberto 'Torres Doug Coleman Closing Remarks Paul Bemis Slide i Comparing WNP-2 9x9-9X Design and Designs Using ULTR WLOW Spacer ULTRAFLOWDesi n
w Produces significant perturbations in water flowaround fuel rods (i.e.,
erases "history")
> ULTRAFLOWspacer design data not contained in ANF-1125(P)(A)
> Additive constants within range ofANF-1125(P)(A)
WNP-2 9x9-9X Desi n
~ "History" effect remaine unchanged x 9x9-9X design data well represented in ANF-1125(P)(A)
n Additive constants within range ofANF-1125{P)(A)
Shdc '
Restatement of Issue (50-397/98-01-01)
a"Licensee oversight ofthe fuel vendor's design processes and controls... failed to detect that an inadequate technical specification limitwas developed. The failure to establish measures to assure that the design bases were correctly translated into technical specifications [is]... an apparent violation ofCriterion III,Appendix 8 to 10 CFR Part 50."
-"licensee failed to ensure that suQicient margin Ntas available in its SLMCPR SAFDL"
-"SPC critical heat fluxdata base did not contain a suQicient number ofdata points to statistically support the advanced nuclear fucl-boiling (ANFB-1125) correlation" Slide 3 Supply System Understanding of NRC's Concern
> Licensee failed to "detect" that vendor supplied inaccurate and non-conservative limits (i.e, limited data points and range used)
~ That failure represents poor vendor oversight
~ The poor vendor oversight resulted in Technical Specifications for the SLMCPR that were not sufficiently conservative.
Slide 4
Relevant Guidance Documents w Topical Reports ANF-1125(P)(A), "ANFB'CriticalPower Correlation," April 1990 ANF-524(P)(A), "Critical Power Methodology for Boiling Water Reactors," November 1990 Shdc 5 Relationship Between ANF-1125 and ANF-524 s ANF-1125 provides the approved experimental data base and statistical characterization of ANFB w ANF-524 prov<des the approved methodology to determine the MCPR safety limit that protects 99.9 percent of the fuel
. rods from boiling transition SlldC C
NRC's Technical Concern
~ ANF-524 procedure to establish the safety limit is not at issue (i.e., how inputs used)
a At issue is how the inputs to At&-524 {i.e.,
correlation and additive constant uncertainty) were generated per ANF-1125 limited data points and test range Stride 7 Relevant Regulatory B.asis SER Limitations for ANFB Critical Power Correlation (ANF-1125)
3.3 Limitations
{3) The use ofthe ANFB correlation shall be limited to assessments with the additive constants given in Reference 2. Ifa new fuel design results in additive constants outside the range of Ref'erence 2, then these must be justified.
Note:
Reference 2 is ANF-ll25(P)(A) Supplement l
Slwk $
Was a new fuel design involved?
w Yes Back ound In Cycle 6, VAR-2 used an 8X8 fuel design In Cycle 7, the 9x9-9X was introduced The 9x9-9X has continued to be in use Slide 9 Is the use of a new fuel design authorized by SER limitation 3.3 (3)?
~ Yes The second sentence in the limitation clearly contemplates that new fuel designs may be used
~ Note: ANF-1125.is aoolicable to WNP-2's fuel design. Onlv more recent designs (e.g.
those using ULTRAFLOWspacers)
are not well represented in the data base Slide lo
Is ANF-1125(P)(A) Applicable to the WM'.-2 9x9-9X fueI?
The design features are we11 reoresented bv ANF-1125 data base (e.g., standard bi-metallic spacers, 9x9 geometry &; 9x9 with water canister)
Geometric and thermal hydraulic similarities and differences (i.e., rod diameter, rod-to-rod spacing, rod-to-wall spacing, assembly hydraulic diameters and heated length)
Sbdc I I Why ANF-1125(P)(A) is Applicable 9x9-9X fuel design z Of2.842 data points in ANFB data base, more than half {approx. 1,500) are for bi-metallic spacer designs Data were collected over cosine, upskew and uniform axial power profiles Thermal hydraulic conditions covered entire range of ANFB critical heat fluxcorrelation a ln excess of300 data points for 9x9 design with internal water canister
~ Design features of9x9-9X fuel are included in Ah!FB data base slide u
Plot ofAllANF-1125 P A Data ANFB Data Base X
ANFB
+10%
10%
Measured Crltlcal Power, MW
Color-Coded Plot ofData for Relevant Fuel Types ANFB OVERLAYS J
C Bimetallic
10%
10%
ATRIUM
Sx9-9X Measured Critical Power, MW
Are the additive constants within the range established by ANF-1125(P)(A)?
a Yes A fullarray 9x9-9X testing was conducted to determine the additive constants Over 80 test points showed critical heat Qux performance well characterized by ANFB Additive constants were within the range ofthe constants found in Section 6 ofANF-1125(P)(A)
slid<< l5 Was the data set size and range sufficient?
\\
m Yes m ANF-1125(P){A),Supp. 1, Section 4.2:
-onlv a few data points at typical operating conditions are required to determine additive constants forone peaking pattern" (emphasis added)
Data set size ofover 80 data points is consistent with the guidance in ANF-1125 Data points at t)yicat operating conditions werc used to determme additive constants for thc 989-9X fuel Data set was favell behaved withrespect to thc correlation(rcterence Table 5 I. ANF-I I25(PXA). Supp. I)
sade In
Was the additive constant uncertainty properly determined?
~ Yes Data set size used to determine uncertainty is consistent with other data sets found in Table 6.2 of ANF-1125(P)(A)
Data set range used to determine uncertainty consistent with range offlow and sub-cooling for other data sets at "typical operating conditions" (i.e., 1,000 psi) in Table A series of ANF-1125(P)(A)
Additive constant uncertainty for the 9x9-9X fuel consistent with uncertainty reported in ANF-1125(P)(A), Table 6.2
{i.e., 9x9-K)
Slide l7 w There was reasonable assurance that the vendor properly applied the topical reports and the NRC SER limitations to WNP-2's fuel design.
~ ANF-1125(P)(A) still remains the NRC approved guidance
~ WNP-2's OER Program identified no relevant industry events Sl>de lS
Safety Significance
~ IfWNP-2 applies the revised safety limitMCPR to Cycles 7-12, then:
Based on actual plant events, the SLMCPR was not exceeded during Cycles 7-12 Based on the actual plantoperating conditions during Cycle 8 (most limitingofCycles 7 - 12), the SLMCPR would not have been exceeded by the mostlimiting transient (LRNB)
Sli* l9 Vendor/Licensee Commitment Under ANSl N45.2.11 Section 6.2 The extent of the design verification required is a function of:
unimportance to safety xcomplexity ofdesign vdegree of standardization estate-of-the-art msimilaritywith previously proven designs Verified for each application with respect to standardized or previously proven designs Slide h'I
Vendor Oversight Program Enhancements R Past Enhancements Conversion to Basic Design Change Process BWROG Peer Review Operating Performance Reviews concerrung staoility Additional stability analysis now required from vendor Established Design Review Board w Future Enhancements BWROG Fuel Vendor Technical Audits Address Recommendations ofBWROG Peer Review Self-Assessment ofReload Design Process Scheduled Slid<<2l Actions Taken
~ Interim Safety Limits Implemented w ABB SLMCPR Methodology Audit a Self Assessment of Vendor Oversight (with Peer Review)
~ 'INPO Evaluation of WNP-2 SOER 96-02 "
Implerrtentation
'S l.evv Report on US96A7/ANFB comparison remseo to orctude additional data
Regulatory Perspective
~ No Violation of Appendix B, Criterion III Regulatory Guidance Properly Applied ANF-1125(P)(A) and ANF-524(P)(A) Provide Technically Sound Methods forEstablishing SLMCPR ANF-1125(P){A)StillRemains the NRC-Approved Guidance
, ~
Vendor OversightProgram Adequate 8c Enhancem ents Have Been and Are Being Made Slide 23 Closing Remarks
~ WNP-2 will continue to exercise a questioning attitude in the area of fuel design a WNP-2 is committed to continuous reassessment of our overall vendor program
~ WNP-2 is committed to staying current with the NRC and Industry improvements Sl<Ck '>
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