ML20207M793
| ML20207M793 | |
| Person / Time | |
|---|---|
| Issue date: | 03/15/1999 |
| From: | Wen P NRC (Affiliation Not Assigned) |
| To: | NRC (Affiliation Not Assigned) |
| References | |
| PROJECT-694 NUDOCS 9903190191 | |
| Download: ML20207M793 (10) | |
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March 15, 1999 MEMORANDUM TO: FILE FROM:
Peter C. Wen, Project Manager Original Signed By:
Generic issues and Environmental Projects Granch Division of Regulatory improvement Programs -
SUBJECT:
D!SCUSSION TOPICS FOR MARCH P.5,1999 MEETING WITH WESTINGHOUSE OWNERS GROUP REGARDING WCAP-14986, REV 1,' WESTINGHOUSE OWNERS GROUP POST ACCIDENT SAMPLING SYSTEM REQUIREMENTS: A TECHNICAL BASIS" The attached message was faxed today to Robert Lutz of the Westinghouse Owners Group (WOG). The sole purpose of the message is to prepare WOG personnel for an NRC/WOG meeting to be held on March 25,1999. The message itself does not cons 6tute a formal request for information or represent a formal staff position; the message will be included in the meetir;g summary.
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Project No. 694 Attachmcnt: As stated cc w/att: See next page i
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MEMORANDUM TO: FILE FROM:
Peter C. Wen, Project Manager d C. W Generic issues and Environmental Projects Branch Division of Regulatory improvement Programs
SUBJECT:
DISCUSSION TOPICS FOR MARCH 25,1999 MEETING WITH WESTINGHOUSE OWNERS GROUP REGARDING WCAP-14986, REV 1, " WESTINGHOUSE OWNERS GROUP POST ACCIDENT SAMPLING SYSTEM REQUIREMENTS: A TECHNICAL BASIS" The attached message was faxed today to Robert Lutz of the Westinghouse Owners Group (WOG). The sole purpose of the message is to prepare WOG personnel for an NRC/WOG meeting to be held on March 25,1999. The message itself does not constitute a formal request for information or represent a formal staff position: the message will be included in the meeting summary.
Project No. 694
Attachment:
As stated i
.cc w/att: See next page s
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l COMMENTS AND QUESTIONS CONCERNING WCAP-14986-P l
" Westinghouse Owners Group Post Accident Sampling System Requirement:
i A Technical Basis,"
The following is a list of comments, questions, and issues on WCAP-14986-P which we plan to discuss during the March 25,1999, meeting between NRR and the Westinghouse Owners Group. In addition we have provided a number of comments related to the lead plant application of this topical at the end of this evaluation.
EVALUATION OF RECOMMENDATIONS
- 1. Sample: RCS Dissolved Gases WCAP Recommendation: Delete From PASS The WCAP recommendation is based upon an analysis of where information on dissolved gasses is used in the EOPs.
l issues:
It is not clear that other post-accident items which might for some designs be affected by dissolved gasses, such as vessel level instrumentation and emergency core cooling system high pressure injection pump performance, were addressed. Please provide a more comprehensive discussion of this topic to address other affected items including, but not limited to, the items cited.
j Same issue as for RCS dissolved gases.
- 3. Sample: RCS Oxygen WCAP Recommendation: Delete From PASS This measurement is specified in Regulatory Guide 1.97. The presence of oxygen can enhance stress corrosion cracking (SCC) caused by chlorides. The WCAP does not recommend measuring oxygen in reactor coolant but indicates that SCC can be prevented by either ensuring that oxygen concentration is low or by adjusting pH.
Issues:
it is not clear how this SCC control can be achieved when pH and oxygen concentration will not be measured.
in order to make a pH estimation, the chemistry of the incoming water from all sources to RCS l
should be known and there should be a procedure at hand for calculating the resulting pH by I
the plant personnel. Will these considerations be addressed in the proposed procedure?
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The WCAP does not discuss whether measurements of boron in the sump might provide information on boron precipitation or boron dilution during an accident. Was this considered when the recommendation for relaxing the sample time was made? Further discussion is needed on this item.
Sample: RCS Radionuclides WCAP Recommendation: Delete From PASS WCAP-14986 concludes that the capability to obtain post accident samples of reactor coolant for radionuclide content is not needed and recommends that this capability be removed from the licensing basis. The rationale for this conclusion is that there are other indicators (e.g., core exit thermocouples and containment high range monitors) which can be used for performing core damage assessments and that these indicators are available earlier than PASS samples.
Furthermore, WCAP-14986 states that the PASS samples would not provide any useful information regarding the extent of core damage because of limitations related to accident conditions and sample capabilities (e.g., plate out in sample lines).
Issues:
The need for PASS is described in the NUREG-0737," Clarification of TMI Action Plan Requirements" and Regulatory Guide (RG) 1.97, " Instrumentation for Light-Water-Cooled Nuclear Power Plants to Assess Plant and Environs Conditions During and Following an Accident." NUREG-0737 specifies that the PASS have the capability to promptly quantify certain radionuclides that are indicators of the degree of core damage. RG 1.97 specifies that the isotopic analysis serves the purpose of accident release assessment. Although other indicators are available to make an assessment of the degree of core damage, PASS samples would provide information useful in confirming or refining estimates of core damage. More importantly, PASS information will be useful in refining release assessments which may be based upon assumed source terms. These dose assessments can be used to confirm (or refine, if necessary) the adequacy of the initial protective action recommendation which was based upon plant conditions. Further discussion is needed on these issues.
- 10. Sample: Containment Radionuclides WCAP Recommendation: Delete From PASS WCAP-14986 concludes that the capability to measure the radionuclide content of the l
containment atmosphere is not needed and recommends that this capability be removed from l
the licensing basis. The rationale for this conclusion is that there are other indicators (e.g., core j
exit thermocouples and containment high range monitors) which can be used for performing j
core damage assessments and that these indicators are available earlier than PASS samples.
Furthermore, WCAP-14986 states that the PASS samples would not provide any useful information regarding the extent of core damage because of limitations related to accident conditions and samp!e capabilities (e.g., plate out in sample lines).
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Issues:
The need for PASS is described in the NUREG-0737 " Clarification of TMl Action Plan Requirements" and Regulatory Guide (RG) 1.97, " Instrumentation for Light-Water-Cooled Nuclear Power Plants to Assess Plant and Environs Conditions During and Following an Accident." NUREG-0737 specifies that PASS have the capability to promptly quantify certain radionuclides that are ind:cators of the degree of core damage. RG 1.97 specifies that the isotopic analysis serves the purpose of accident release assessment. Although other indicators are available to make an assessment of the degree of core damage,it seems that PAGS I
samples would provide information useful in confirming or refinir'g estimates of core damage.
More importantly, it seems that information regarding the radionuclide concentration in the containment provides the best information on the source term for use in performing dose assessment of the potentialimpact of a release from the containment. This information will be usefulin reGning release assessments which may be based upon assumed source terms.
These dose assassments can be used to confirm (or refine, if necessary) the adequacy of the initial protective action recommendation which was based upon plant conditions. Further discussion is needed on these issues.
- 12. Sample: Sump Chlorides WCAP Recommendation: Delete From PASS WCAP-14986 proposes to delete the capability for measuring chlorides in the containment. In its analysis it considers the case of brackish or salt water plants having no passive pH control.
WOG suggest that in this case the amount of chloride in the sump could be estimated by monitoring level of sump water and predicting its chlorde content from the chloride content in the water sources injected into the contain' ment.
Issues:
How accurate is this method, especially when this estimate is performed by the plant operators engaged in several other pressing operations.
The WCAP does not discuss wheths.r measurements of boron in the sump might provide j
information on boron precipitation or boron dilution during an accident. Was this considered when the recommendation for relaxing the sample time was made? Further ciscussion is needed on this issue.
- 14. Sample: Sump Radionuclides WCAP Recommendation: Delete From PASS lasues: Same as for Containment and RCS Radixuelidt.s sample.
GENERAL COMMENT
S /OUESTIONS
- 1. Removalof Requirements from Licensing Basis WCAP-14986 recommends that the capability to obtain certain samp!es be deleted as a requirement but retained to assist in planning long term recovery action (but not within the plant
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licensing basis). It is not c! ear what is meant by removing the capability from the licensing
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or eliminated.
- 2. Benefit of Modification of PASS Requirements Neither the WCAP nor the pilot plant submittalidentified a significant burden with maintaining the PASS capabilities (the pilot plant submittal did identify a significant burden with maintaining the on-line sampling capability ). The pilot plant identified that it had the capability to obtain and analyze a grab sample (this is currently a backup to the online system). It is acceptable for the licensees to discontinue use of on-line PASS system, as long as the capability to promptly obtain and analyze PASS samples exist.
- 3. Plugging of PASS Lines WCAP-14986 states that one rationale for not taken PASS samples is due to the potential for plugging in the sample lines. However, in accordance with NUREG-0737, these sample lines were to be designed to prevent plugging and plateout. Further information is needed to ev%ua'e the predicted extent of plugging and plateout in the samp!e lines (see also specific j
comment #3).
SPECIFIC COMMENTS
- 1. Page 3, Para. 5 WCAP-14986 states that "Reguiatory Guide 1.97 represents the latest NRC positions on post accident sampling and, as such, supersedes the iaquirements in NUREG-0737." Regulatory Guide 1.97 provides methods acceptable to the 63C for meeting the requirements of General Design Criteria 64 in Appendix A to 10 CFR Part 50. NUREG-0737 provides clarification to TMI Actica plan requirements which were imposed on licensees by orders. Regulatory Guide 1.97 does not supercede NUREG-0737 requirements imposed by orders.
2.
' age 4 Table 1 The table contains an editorial error (10 mci /ml should be 10 pCi/ml). This error (use of mci in place of pCi) is repeated in a number of places in the WCAP.
- 3. Page 8, Paragraph 2 WCAP-14986 states that recent analytical studies have indicated that dense aerosol concentration in the RCS and the containment could plug sample lines. Please :rovide the referred to studies. Clarification 11 to NUREG-0737 item II.B.3 states that the PASS should have " Provisions for purging sample lines, for reducing plateout in sample lines, for minimizing sample loss or distortion, for preventing blockage of sample lines by lose material in the RCS or containment." Please provide further information on why the provisions put in place to meet this NUREG-0737 item are not adequate.
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4.
Page 9, Paragraph 1 i
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WCAP-14986 states that the investigation that resulted in development of a new core damage t
assessment methodology conclJded that the results of radioactivity analyses of samples of plant fluids was too unreliable to make prediction regarding the amount of core damage that has occurred. The rationale for this conclusion was that the transport and deposition of radionuclides in the plant is very dependent on the details of the accident and that the time.
Further information is needed to conclude that PASS canr:ot be used to predict the amount of core damage. It seems that PASS samples can provide additional inforr ation to supplement that provided by other ir,dications. In particular the PASS can provide indication of the extent of i
core damage relative to clad damage versus core overtemperature or core melt by the presence of volatiles or non-volatiles in the samples.
- 5. Page 9, Paragraph 2 WCAP-14986 states that radiological analysis of plant fluids was not useful for emergency action level classification. It is not clear what the spectrum of accidents were evaluated that lead to this conclusion. The criteria included in the EAL scheme equates to approximately 2 -
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5% clad damage. At these levels of clad damage, it is not clear that other parameters would prompt classification. Paragraph 3 on page 16 describes classification of a reactivity excursion i
I event. It seems that a reactor coolant sample may be the only indication of clad damage for l
this event.
- 6. Page 11, Paragraph 5 WCAP-14986 state that the NRC approved deletior. of the requirement for heat tracing of sample lines. The NRC stated in that a licensee that utilizes iodine in its cere-damage assessment procedures must include appropriate design consideratiori to ensure representative sampling. It is not clear how xenon and/or kryton isotopic analysis can be used to ascertain the degree and tvoe of core damage.
- 7. Page 16, Paragraph 1 It is not clear what is meant by the statement that "the third class of accident is similar to the composite core damage classifications described in NUREG-0737."
- 8. Page 27. paragraph 1 l
WCAP-14M6 states "from the perspective of emergency response, there are only three levels of core damage that are important: no damage, fuel rod cladding damage and fuel over temperature damage. The maiority of the noble gas and volatile fission products are alreacy released from the fuel prior to the or. set of core melting. These are also the most important fission products (i.e. noble gases, todines and cesiums) from an offsite radiological protection l
perspective. The small quantities of nonvolatile fission products that may be released only at core melting are not as important with raspect to emergency response activities." This needs to be further justified, i.e., provide the information regarding what the additional quantities of radioactive material are released and how ex-vessel releases were modeled.
- 9. Page 43, Section 4.3.2 l
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WCAP-14986 provides :nformation regarding the use of source term information to make dose assessment. This section discusses various ways that the source term can be obtained, including use of precalculated values (e.g., from design basis or PRA sources) or use of containment high range area radiation monitor, but does not provide information on the relative accuracy of the different means of obtaining source term data.
- 10. Page 44, Section 4.3.3 WCAP-14986 states that the NEl EAL scheme suggests a value of 300 mci /cc equivalent 1-131 as an EAL criterion at the Unusual Event level. This is incorrect. As identified previously the value is 300 pCi/cc. Furthermore the event is classified in the fission product barrier at the Alert level unleds other fission product barriers are lost or potentially lost (in which case it is classified at a higher level).
- 11. Page 44, Section 4.3.3 WCAP-14966 discusses an assessment performed to identify possible accident sequences where the RCS fission product inventories can approach EAL trigger values. Please provide details of the assessment in particular provide information on how reactivity excursion events and events involving the potential clad damage due to flooding with cold water were evaluated.
COMMENTS SPECIEC TO LEAD PLANT (WOLF CREEK) APPLICATION OF WCAP
- 1. For several PASS functions, the Wolf Creek Nuclear Operating Company (WCNOC) submittal states that the post-accident sampling function can be deleted, but that "...for long term monitoring, the capability will be retained (but not within the plant licensing basis)..."
Please provide the following:
- a. Clarification of what is intended by the statement that the capability would be retained for long term monitoring. A specific statement of which sampling and analysis capabilities and/or hardware would be retained and which would be deleted or relaxed should be provided for each PASS function. This should clearly indicate where WCNOC plans to retain / delete / relax the on-line monitoring capabilities, the grab sample capabilities, the time required to obtain samples, and the time required to analyze samples.
- b. Clarification of wnat is intended by the statement 'not within the plant licensing basis." If this means that the system or function is completely removed from the FSAR, explain what controls would prevent the system and function from being eliminated at a later date without the approval of the NRC.
- 2. For several PASS functions, the WCNOC submittal states that the parameter can be approximated from calculations (e.g., RCS and sump pH). Please describe the calculation aids currently in place or planned at Wolf Creek Generating Station (WCGS) to predict the chemical content of the RCS or sump water (i.e., pH and chlorides) based on the quantities and chemical content of water added to the RCS or sump from other sources.
- 3. The WCNOC proposal regarding RCS radionuclide sample and analysis capabilities is very vague. It implies that the PASS function will be deleted for the short term (transient phase),
but that the related EALs will not be deleted. Please describe how radionuclide samples of the reactor coolant system will be obtained for use in classifying events using these EALs.
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- 4. The WCAP and the text of the WCNOC submittal seems to indicate that containment atmosphere hydrogen can be dete. mined via either: (1) the safety grade on-line hydrogen monitor (required by 10CFR50.44), or (2) sampling and analysis using PASS, provided the initial measurement can be made within 30 minutes, and at 10 to 15 minute intervals thereafter. This discussion does not indicate or discuss WCNOC's prorosal regarding
. ASS hydrogen measurement capabilities. This is only mentioned in Table 1. The statement in the table should be brought into the text and discussed further.
- 5. The discussion of containment atmosphere oxygen on page 19 of the WCNOC submittal states that the capability to measure containment oxygen concentration is not a NUREG-0737 or a Regulatory Guide 1.97 function for PWRs. However, containment oxygen is indicated to be a required parameter on page 6 and 7 of the submittal. Please clarify this apparent inconsistency.
- 6. The discussions in Section IV indicate that long term monitoring capabilities will be retained for several PASS functions. However, Table 1 does not indicata this, and simply states that these functions would be deleted from PASS. Table 1 should be modified to identify those areas where long term monitoring capabilities will be retained.
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Westinghouse Owners Group I
Project No. 694 cc:
Mr. Nicholas Liparulo, Manager Equipment Design and Regulatory Engineering Westinghouse Electric Corporation Mail Stop ECE 4-15 I
P.O. Box 355 Pittsburgh, PA 15230-0355 l
Mr. Andrew Drake, Project Manager Westinghouse Owners Group Westinghouse Electric Corporation Mail Stop ECE 5-16 P.O. Box 355 i
Pittsburgh, PA 15230-0355 i
Mr. Jack Bastin, Director i
Regulatory Affairs l
Westinghouse Elc. '*ric Corporation 11921 Rockville F:.<e Suite 107 I
Rockville, MD 20852
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I Mr. Hank Sepp, Manager Regulatory and Licensing Engineenng Westinghouse Electric Corporation i
PO Box 355 l
Pittsburgh, PA M230-0355 1
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