ML20214P416
| ML20214P416 | |
| Person / Time | |
|---|---|
| Issue date: | 05/27/1987 |
| From: | Leech P Office of Nuclear Reactor Regulation |
| To: | Kintner E GENERAL PUBLIC UTILITIES CORP. |
| References | |
| PROJECT-669A NUDOCS 8706030370 | |
| Download: ML20214P416 (8) | |
Text
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May 27, 1987 Project ha. 669 Mr. Edwin E. Kintner, Chairman ALWR Utility Steering Committee GPU Nuclear Corporation l
One Upper Pond Road Parsippany, New Jersey 07054 Dear Mr. Kintner-l SdBJECT: REQUEST FOR ADDITI0fiAL INFORMATION RELATIVE TO CHAPTER 2, ALWR REQUIPEMENTS DOCUMENT During the staff's consic ~stion of Chapter 2 of the ALWR Requirements l
Document, we have determined that additional information is needed in order to complete our review.
Enclosure : provides the comments and questions by the staff and Enclosure 2 provides those of Scie tech Inc., our independent I
censultant.
Based L'pon the response tirre required for our questions regarding Chapter 1, we estimate that we can expect your response to this request by Septerrber 1, 1987.
If you anticipate that it can be provided earlier, please inform us and we will plan accordingly.
Sincerely, Original signed by i
i Paul H. ' eech, Project Manger Standardization and Non-Power Reactor Project Directorate Division of Reactor Projects III, IV, V and Special Projects l
Office of Nuclear Reactor Regulation i
Enclosures:
As stated l
I cc: Daniel T. Noble, EPRI l
DISTRIBUTION l
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ah; v Ma.y 27, 1987 Project No. 669 Mr. Edwin E. Kintner, Chairman ALWR Utility Steering Committee GPU huclear Corporation Ora Upper Pond Rcad I
Parsippany, New Jersey 07004
Dear Mr. Kintner:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION RELATIVE TO CPAPTER 2, ALWR REQUIREMENTS DOCUMENT During the staff's consideration of Chapter 2 of the ALWR Requirements Document, we have determined that additional information is needed in order to complete our review. provides the comments and questions by the staff and Enclosure 2 proYides those of Scientech Inc., our independent consultant.
Based upon the response time required for our questions regarding Chapter 1, we estimate that we can expect your response to this request by September 1, 1987.
If you anticipate that it can be provided earlier, please inform us and we will plan accordingly.
o H
Sincerely, i
Q Ju Paul H. Leech, Project Manger Standardization and Non-Power Reactor Project Directorate l
Division of Reactor Projects III, IV, l
V and Special Projects Office of Nuclear Reactor Regula+ ion
Enclosures:
As stated cc: Daniel T. Noble, EPRI I
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4 NRC Staff Comments and Questions Relative to Chapter 2 of the EPRI Requirements Document Section 2.0 - Common Requirements 1.
Paragraph 2.1 requires that the pcwer generation systems covered by Chapter 2 "shall comply with the overall requirements of Chapter 1."
On page 10-1 of Chapter 1 we note the statements that Appendix B lists the NRC regulations and guidelines that are currently applicable to LWR design and that exceptions to this list will be identified on a chapter-by-chapter bcsis.
Since no exceptions are so identified, are we correct that the Standard Review Plan (SRP) fully applies to this chapter?
If there are any exceptions, please ;dentify the; specifically and reference or state the rationale 4%
their acceptability.
2.
The general lack of references to specific industry and government standards in Chapter 2 is in marked contrast to the referencing policy in Chapter 1.
Such references would be useful to users of the document and would help us to verify that the applicable regulatory requirements are addressed.
3.
One requirement that is not addressed concerns the design of safety related portions of the power generation systems to withstand and/or be protected from seismic events and other natural phenomena. Another requirement not addressed is environmental qualification for operating conditions. While these are site / plant specific, EPRI may wish to state which portions of the systems need to be considered and the design limitations, if any.
4.
Section 2.2.A (Page 2-1) states that " Leak-before-break analyses should i
be applied to the high energy main steam and feedwater lines in order to reduce analysis requirements and to eliminate hardware associated with the dynamic effects of breaks in these lines." As indicated in our letter to Dr. C. F. Sears of Northeast Utilities, dated June 6, 1986, l
the NRC is processing a rule change to GDC 4 which will allow the application of leak-before-break methodology to piping. However, to date, the staff has not approved leak-before-break for balance of plant systems.
5.
Section 2.2.B (page 2-2) states that, where possible, valving functions should be consolidated and gives the following exanple:
'Use of three-way valves for isolation and bypass." A three-way valve may not be acceptable for isolating safety related systems or portions of safety I
related systems.
The ALWR requirements should address the conditiors that must prevail for this approach to be acceptable, how it should be invoked, permissible leakage, and consideration of valve failure. The guidance should also specify that no portion of the plant piping shall be not available for pressure testing because of lack of valving for isolation.
1 Section 3.0 - Main / Extraction Steam System 6.
Interface Criteria 1 (page 3-2) states "The Reactor Coolant System (Chapter 3) provides stean to the Main Steam System." This statement is j
true for a BWR, but not for a PWR.
7.
Performance Requirement 3.2. A.3.c (page 3-8) states that "The electrical and hydraulic power system [for the BWR Steam Bypass System] shall be designed to assure operability of the bypass valves upon loss of offsite or station auxiliary power for a minimum time of five seconds." The engineering rationale for this statement is "To ensure steam flow path after turbine generator trip and during electrical power loss".
In order to accomplish this, the bypass valves would need to be opened either automatically or manually upon a loss of electrical power (LOP) and a turbine trip. There would be no assurance that the valve would close l
since the system is a non-safety system.
This could cause problems in reactor cooldown.
In addition, the statements contradict specific valve requirements in Section 2.2 (page 2-3) on the use of hydraulic actuators, and Section 3.5.c on maintaining bypass valves closed upon loss of the condenser which would occur upon a LOP.
The statement should be deleted, or proper justification for the criterion should be provided.
8.
SRP Section 10.3 requires, for PWR's, that in the event of a postulated SSE and a concurrent loss of offsite power, the main steam system design shall include the capability to operate the atmospheric dump valves remotely from the controi room so that cold shutdown can be achieved using only safety grade components. This requirement needs to be addressed.
9.
Issue Number 1 of NUREG-0138, " Staff Discussion of Fifteen Technical Issues Listed in Attachment to November 3, 1976 Memorandum from Director, NRR to NRR Staff," related to credit being taken for all valves downstream of the MSIV's to limit blowdown of a second steam generator in the event of a steam line break upstream of the MSIV. A licensee for a nuclear plant needs to show that the shutoff valves downstream of the MSIV can close against roe maximum steam flow, that they will be functional (have motive 3wer) and are quality valves that have been designed to industry design codes, or show tnat the steam flow through all the branch lines downstream of the MSIV is less than or equal to the Auxiliary Feedwater flow to the second steam generator. The ALWR requirements for the main steam system do not address this subject.
10.
SRP Sections 10.3 and 10.4.7 state that the Main Steam and Main Feedwater Systems piping design should adeauately consider loadings due to steamhammer, relief valve discharge loads, and/or waterhammer, in addition to static, dynamic and seismic loads. The ALWR requirements for these two systems do not address this subject.
- Section 4.0 - Feedwater and Condensate System 11.
Section 4.5.C (page 4-49) states that "The number of reactor or turbine trips which originate in the feedwater and condensate system shall be minimized.... Power cutbacks should be considered in lieu of trips...."
This ALWR requirement may not be in conformance with SRP Sections 10.4.7, 15.1.1. through 15.1.4, and 15.2.7, which deal with maintaining primary system pressure boundary integrity and with fuel damage.
The requirement should be expanded to deal with this aspect of reducing trips.
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- 12. Section 4.5.E item c. (page 4-51) states that the steam extraction valves l
shall be checked at regular and frequent intervals to determine valve and actuator operability. The intervals should be defined in terms of minimum and maximum time intervals.
Section 5.0 - Chemical Addition System 13.
Section 5.5.B, Item 3 (page 5-8) requires that an analyzer with alarm shall be provided downstream of the offgas recombiner to alarm at 5%
cxygen by volume.
The contradicts 5.3.B.4, which specifies a minimum of 20% oxygen by volume at this location.
Section 6.0 - Condensate Makeup Purification System
- 14. Section 6.3.A (page 6-4) states that crganic carbon can break down to produce sulfides and chlorides. How can this occur?
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i Selected Scientech Comments and Questions Relative to Chapter 2 i
of the EPRI Requirements Document i
S1: Page 2-1, Paragraph 2.2.8 Concerning the use of double block valve design in order to reduce welding, such uses could also reduce ability to isolate systems and later 1
in plant life this could be an overriding factor.
If one of the valve sections required replacement, the plant conditions required to replace it may be vastly different as both valves would have to be removed and one valve could not be used for isolation. A failure of one valve in this situation could delay or prevent startup by many weeks and could require redesign of the piping system.
S2. Page 2-2, Paragraph 2.2.8 Regarding the item " Elimination of equipment and instrumentation that is not essential to the function of the system", we suggest adding the words "and safety".
S3: Page 2-2, Paragraph 2.2.B While standardization of valve types is needed to simplify maintenance and spare parts, the precept that one or two sizes will suffice for valves 2-inches or less may not be a sound one. There are numerous places where a standardized 1-inch valve will not do for a gage isolation or a sample tap. To utilize one or two sizes would require the use of valves too large for some applications, which could lead to more problems l
than were solved by standardization.
It would be better to use valves of the same manufacture and type, i.e. globe, gate, needle, etc.
t S4: Page 2-3, Paragraph 2.2.C This paragraph should refer the reader to Chapter 1, Section 5.0
" Materials". Additionally, will requirements be established with regard to erbrittlement and the need for material surveillance?
l S5:
Page 3-5, Paragraph 3.2.A.I.b Turbine trip without reactor trip has not been approved by the NRC.
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' S6:
Page 3-8, Paragraph 3.2.3.d This paragraph needs to be clarified.
If a condition inhibits bypass opening and initiates a trip, making the trip occur prior to inhibiting the valve opening will not ensure bypass capability after the turbine has tripped.
It will be inhibited.
S7:
Page 3-10. Table 3-1 Seat tightness is required in both directions for the same design conditions; however, the reverse flow leak rate that is acceptable is significantly higher than the forward flow rate. The table assumes the use of a gate valve in the design.
S8:
Page 3-10, Table 3-1 How are the valve characteristics " structural integrity and functional operation during normal, upset, emergency, and faulted conditions" to be satisfied? By conformance to Code ;ections III and XI?
59:
Page 3-12, Paragraph 3.3.A.5 Section 3.3.A should discuss arrangements related to systems branching off of the main steam system ((e.g. emergency feedwater (EFW) system turbine-driven pumps)). An EFW system is usually valved closed until the pumps are needed. When the valves are opened, steam condensation and water hammer often occur with the attendant overspeed trip of the pump.
Some units have eliminated this problem by heat tracing or good piping arrangements which include automatic drains piped to the condenser.
510: Page 3-19, Paragraph 3.4.A.3 The use of carbon steel, with an expected life of 25 years, for the main steam and hot rehes.t piping appears inconsistent with achieving a 60-year plant lifetim "without necessity for an extended refurbishment outage".
l This implies that such piping will be replaced at least once during the 60-year period and raises a question as to how long an outage would be necessa ry.
Also, would the use of carbon steel decrease safety margins as compared to using stainless steel or chrome moly?
S11: Page 3-23, Paragraph 3.4.C.3.a j
The main steam line relief valves should be operable from both the control room and the remote shutdown panel, not one or the other.
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S12: Page 3-24, Paragraph 3.5.C.3.e Single valve isolation for work on high energy systems is not normally advocated by safety personnel or plant maintenance personnel.
It is done only when absolutely needed and then special administrative controls are established. Ar, additional (manual) valve should be placed in the line.
l S13: Page 4-6, Paragraph 4.2.A.10 While it is true that eliminating the trip on low NPSH would keep the pumps running, it could also present a real personnel hazard from damaged pump parts. Additionally, the potential high repair rate and cost of replacement of very expensive pump parts and possible extended down time may offset the inconvenience and short off-line periods caused by loss of feed pumps due to momentary loss of suction pressure.
S14: Page 4-9, Paragraph 4.2.C.3 The rationale does nst seem consistent with the requirement in Paragraph 4.2.A.a that " plant operation shall be possible at 100% power with loss of one operating feedwater pump."
S15: Page 4-18, Paragraph 4.3.0 Are the sizing requirements for the feedwater booster pumps the same as for the condensate pumps, i.e. 3 X 50%?
l S16: Page 4-26, Paragraph 4.3.J.2.a l
The requirement of using a side stream polisher does not appear to be l
consistent with the rationale of Section 4.3.J.1.a, where a full flow l
system may be required.
S17: Page 4-38, Table 4-1 If the material selected for heaters /deaerator is so susceptible to damage from layup that it cannot withstand 4 days of wet layup, or even I
dry layup, then the material needs to be reevaluated for suitv>ility.
No minimum shutdown time is specified as not requiring layup procedures.
518: Page 4-50, Paragraph 4.5_.C 1
The rationale se to call for elimination of trips caused by turbine island trip funcs..is and hardware.
Is it the intention to make this equipment meet safety grade requirements?
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