ML20028B929
| ML20028B929 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood, 05000000 |
| Issue date: | 12/02/1982 |
| From: | Tramm T COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 5488N, NUDOCS 8212070249 | |
| Download: ML20028B929 (5) | |
Text
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N Commonwccith Edison 3 /')
one First National Plaza. Chicago. Ilknois v
Address Reply to: Post Office Box 767 j Chicago. Illinois 60690 December 2, 1982 4
Mr. Harold R. Denton, Director Of fice of Nuclear Reactor Regulation U.S.
Nuclear Regulatory Commission Washington, D.C.
20555
Subject:
Byron Station Units 1 and 2 Braidwood Station Units 1 and 2 Seismic Qualification Audit Pump and Valve Operability Audit NRC Docket Nos. 50-454, 50-455, 50-456, and 50-457
Dear Mr. Denton:
The purpose of this letter is to clarify the Byron /Braidwood Seismic Qualification Program and Pump & Valve Operability Program which have been evaluated in the Byron SER and further reviewed in an audit at Byron Station during the week of September 13, 1982.
Seismic Qualification Program The methods for seismically qualifying safety related mechanical and electrical equipment are described in detail in Sections 3.9 and 3.10 of the Byron /Braidwood FSAR.
Seismic qualification of safety-related mechanical equipment has generally been accomplished by analytical methods.
Operability of pumps and valves are demonstrated by using analytical methods since it is not practical to perform type tests on a pump-motor assembly or valve-operator assembly.
These analytical methods consider the interaction of the motor on the pump assembly.
Qualification by analysis of safety related mechanical equipment, therefore, assures that equipment stresses are within allowable values and that calculated deflections are less than tolerance requirements to ensure equipment operability.
Seismic qualification o f Class 1E electrical equipment and instrumenta-tion has generally been accomplished by performing type tests using methods consistent with IEEE-344-1975 and the commitments in the FSAR Section 3.10.
However, for some large Class 1E electrical equipment such as motors, qualification has been accomplished by using analytical methods.
These analytical methods have been supplemented by actual type tests or motorette tests on aged samples as recommended by IEEE-334.
Similarly, valve operators have been qualified by performing type tests as recommended by IEEE-382 and IEEE-323.
hoV8 8212070249 821202 PDR ADOCK 05000454 E
,1 H. R. Denton December 2, 1982 Active instrumentation has been qualified by tests.and operability has been demonstrated during and following the actual seismic tests.
Th e program outlined above has been reviewed by the NRC staff and their conclusions are described on page 3-45 of the Byron SER:
"The Seismic Qualification Review Team (SQRT) has reviewed the methodology and procedures o f the equipment seismic and dynamic qualification program contained in the pertinent FSAR Sections 3.9.2, 3.9.3, and 3.10.
The acceptance criteria used as the basis for evaluation are set f orth in the SRP Section 3.10, where guidelines for implementation of the requirements o f the acceptance criteria are also provided.
The SQRT has concluded that the information contained in the FSAR outlining the standards and the general scope of the cualification program does meet the intent of the current licensing criteria as described in SRP Section 3.10."
Audit Issues The following discussion addresses specific issues which were reviewed at Byron Station during the SQRT audit:
1.
Sequential Testing:
Evidence of sequential testing as required by IEEE 323-1974 for Class 1E electrical equipment and instrumentation in plant harsh areas is included in the Byron /Braidwood Environmental Qualification Program which is scheduled to be audited by the Equip-ment Qualification Branch in the near future.
It is our position that evidence of sequential testing need not be -presented to the same Branch o f the NRC twice.
The justification for no sequential testing of mechanical equipment will be included in the Byron /Braidwood Mechanical Equipment Qualification Program to be submitted shortly.
In addition, the " Seismic and Dynamic Qualification Summary o f Equipment" forms do not call for evidence of sequential testing nor have we received any other written request for evidence of sequential testing prior to the SQRT audit.
1 2.
Seismic Reassessment:
A summary statement regarding the seismic reassessment of equipment to the Marble Hill Regulatory Guide 1.60 spectra has not been attached to the SQRT form to be completed for all pieces of Safe Shutdown Equipment.
The Byron /Braidwood design basis seismic spectra are the original deconvolved spectra documented in the FSAR.
To provide additional assurance of seismic design margin, a reassessment program was undertaken to evaluate structures and safe shutdown components to the Marble Hill R.G.
1.60 seismic spectra.
The results o f this reassessment program were reviewed and approved by the NRC as described in Section 3.9.2.2 of Supplement No.
1 to the Byron SER.
In addition, an audit by the Mechanical Engineering Branch was conducted in the offices of Sergent & Lundy to verify the procedures used to demonstrate the seismic qualification for mechanical equipment when compared to Marble Hill R.G.
1.60 spectra.
No additional documentation is considered necessary for SQRT.
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r H. R. Denton Dscember 2, 1982 3.
Qualification by Analysis for Pump Motors:
As stated above in the general description of the seismic qualification of Class 1E equipment, some motors have been qualified using analytical methods.
Most large components, such as motors, have clearly defined critical areas that can be modeled accurately by analytical techniques.
The selection of testing and/or analysis is based on practical considera-tions.
FSAR Sections 3.9.2.2.1 " Seismic Te sting and Analysis",
- 3. 9. 2. 2. 2. 2 "Seismi c Analy si s",
3.9.3. 2.1.1 "B OP Seismic Analysis o f Pumps", 3.9.3.2.3 "NSSS Pump Motor & Valve Operator Qualification" all provide the justification for seismically qualifying pump motors by the analysis option.
Furthermore, no specific findings concerning
" analysis vs. testing" were cited on individual pieces of equipment selected for the audit.
4.
40-year Surveillance and Maintenance Program:
A maintenance program for equipment required to retain its qualified status has been established and is described in the Byron /Braidwood Equipment Qualification Program submitted to the NRC staf f in June, 1982.
5.
File Retrievability:
Commonwealth Edison is in compliance with all requirements of 10CFR50 Appendix B including the requirements for maintaining documentation in an auditable manner.
We are not aware of any requirement for all documentation to be available onsite during the construction stage of the plant.
By the fuel load date of Byron Unit 1. all documentation required to be maintained at the plant site will be in place.
Pump and Valve Operability Assurance, Program As described in sectimi 3.9.3.2 o f the Byron /Braidwood FSAR, an operabi-lity assurance program has been established to assure active pumps and valves will perform their intended safety function during the life of the plant under postulated plant conditions.
Ac tive mechanical equipment is that Seismic Category I equipment which must perform a mechanical motion during the course of shutting down the plant or mitigating the consequences of an accident.
Active pumps and valves are listed in Tables 3.9-15 and 3.9-16 of the FSAR respectively.
Testing, analysis, a combination o f testing and analysis, or previous operating history are acceptable design methods for assuring operability of components for all expected combinations of loadings.
Vendor in-shop tests or analyses, preoperational tests, hot functional tests and periodic inservice surveillance form the basis for this program.
In the case of vendor in-shop tests or analyses, acceptance criteria for operability is provided in the component procurement specification.
The procuremen t specification specifies seismic qualification criteria, pipe reaction end loads (including weight, thermal and seismic load s), environmental conditions, design transients, system operation requirements, special test requirements, and other considerations which are important in the overall design of the components.
Verification that the vendor has complied with all design requirements set forth in the component procurement specification assures operability of the component for its intended safety function.
Conformance to current seismic qualification and environmental qualification parameters is verified by independent programs.
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H. R. Denton Dscembe r 2, 1982 Byron /Braidwood Station personnel will develop and implement pre-operational and hot functional test procedures prior to plant operation.
Inservice Surveillance conforming to ASHE Code,Section XI requirements will be conducted periodically to assess operational readiness of pumps and valves during their service life.
All vendors supplying active components maintain an approved. Quality Assurance Program commensurate with the requirements set forth in 10CFR50, Appendix B.
The vendor's Quality Assurance Program provides for effactive implementation of procedures, instructions, or reviews to ensure that all testing and analyses are accomplished in compliance with tne specification and applicable codes and standards.
Pumps Operability 4
Active pumps are qualified for operability by first being subjected to vendor in-shop tests as required by the component procurement specification.
The in-shop mechanical tests include hydrostatic tests of pressure retaining parts and pump performance tests.
Hydrostatic test procedures 1
and reports conform to ASME Code Section III requirements.
Pe rf o rmance tests are completed in accordance with Hydraulic Institute Standards.
Generally, the pumps are run at design flow and head, shutof f head,120%
of design flow, and two intermediate points to verify performance i
characteristics.
NPSH requirements are determined by test for each pump from 0 to 120% of design flow.
Verification that tunning clearances are adequate and that vibration and noise levels are within acceptabe limits is recorded during performance tests.
All Class 1E equipment associated with active pumps meet the qualification requirements o f IEEE 323-1974.
Valve Operability Active valves are qualified for operability by first being subjected to vendor in-shop tests as required by the component procurement specification.
l The in-shop mechanical tests include shell hydrostatic or pneumatic tests to ASME Code Section III requirements, backseat and main seat leakage tests, disc hydrostatic tests, and functional tests to verify that the valve will open and close within the specified time limits when subjected to the design differential pressure.
Where functional tests to verify opening and closing capabilities are not practical, analysis is used to assure operaollity.
Where required, impact testing is performed in accordance with ASME Code Section III.
j The active valves are seismically qualified by tests or analyses per the l
requirements o f IEEE 344-1975.
All Class 1E equipment associated with active valves meets the sequential testing requirement of IEEE 323-1974.
i For motor operated valves, analyses are performed to verify compatability of operator torque output versus valve torque requirements.
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H. R. Danton December 2, 1982 The NRC staff has reviewed this program as outlined in the Byron /Braidwood FSAR and has reported their conclusions in Supplement 1 to the Byron SER.
There were no technical inadequacies noted in the evaluation of the program other than the question of qualification by analysis alone vs.
testing.
Audit Issues 1.
Seismic and Environmental Design Basis:
As part o f the normal Sargent & Lundy qualification review the seismic qualification of equipment is evaluated to the most current seismic conditions.
This activity is verified by the NRC through the SQRT audit.
As part o f the Environmental Qualification Program, equipment is evaluted against the most current environmental conditions.
This program will also be audited by the NRC staff.
2.
Seismic Testing in Combination with Full Flow Testing:
There is no requirement to perform seismic testing in combination with full flow testing on any pumps or valves.
Demonstrating operability in this regard is accomplished by analysis, as justified above and in the FSAR.
Furthermore, seismic testing in combination with full flow testing is a very impractical method for demonstrating operability.
3.
Sequential Operability Testing:
As discussed in regard to the SQRT audit, there is no requirement to perform any sequential testing on pumps.
The analytical approach adequately addresses any potential f ailures that could result from sequential testing.
4.
Component Installation Status :
The criteria for determining if a component is completely installed should be related to the purpose of the audit.
Incomplete installation details which have no real effect on the seismic performance of the component should not constitute an incomplete installation for the purposes of this audit.
From this standpoint, over 85% of the equipment is installed.
In summary, the technical content o f our seismic qualification and pump and valve operability programs was previously reviewed and approved by the NRC as outlined above.
It appears that the site team conducted their audit against criteria other than those in our approveo programs.
We believe that our present programs are more than adequate to assure equipment operability.
We are available to meet with you or your staff to discuss these matters.
Very truly yours, k
.A&n T.R. Tramm Nuclea r Licensing Administrato r 5488N