ML20138L178
| ML20138L178 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 10/25/1985 |
| From: | Murphy W VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | Vassallo D Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, RTR-REGGD-01.097, RTR-REGGD-1.097 FVY-85-99, GL-82-33, NUDOCS 8510310211 | |
| Download: ML20138L178 (10) | |
Text
o VERMONT YANKEE NUCLEAR POWER CORPORATION FVY 85-99 RD 5, Box 169, Ferry Road, Brattleboro, VT 05301 g,pty70 p
ENGINEERING OFFICE 1671 WORCESTER ROAD FRAMINGHAM, MASSACHUSETTS 01701 TELEPHONE 617-872-8100 October 25, 1985 U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Attn:
Office of Nuclear Reactor Regulation Mr. Domenic B. Vassallo, Chief Operating Reactors Branch No. 2 Divisic a of Licensing
References:
a)
License No. DPR-28 (Docket No. 50-271) b)
Letter, VYNPC to USNRC, FVY 84-127, dated 10/30/84, "NUREG 0737, Supplement No. 1 - Regulatory Guide 1.97" c)
Letter, USNRC to VYN 'C, NVY 84-263, dated 12/12/84 d)
Letter, USNRC to VYNPC, NVY 85-173, dated 8/19/85,
" Request for Additional Information Following Preliminary Staff Review of Licensee Response to Generic Letter 82-33" e)
Letter, USNRC to VYNPC, NVY 85-187, dated 8/29/85
Dear Sir:
Subject:
Additional Information in Response to Preliminary Staff Review of NUREG 0737, Supplement No. 1 - Regulatory Guide 1.97 Submittal By letter dated August 19, 1985 [ Reference d)], you requested additional information following the preliminary staff review of our October 30, 1984
[ Reference b)] response to Generic Letter 82-33 concerning conformance to Regulatory Guide 1.97, Revision 3.
In accordance with your request, Attachment A to this letter provides a response to each of the identified open items.
Attachment B to this letter provides a discussion of items in our October 30, 1984 submittal which we have subsequently determined to require clarification or correction.
In our October 30, 1984 submittal [ Reference b)], we provided the results of our engineering assessment of Regulatory Guide 1.97, Revision 3,
" Instrumentation for Light-Water-Cooled Nuclear Power Plants to Assess Plant and Environment Conditions During and Following an Accident." This letter defined three categories of equipment:
1.
equipment which is in full agreement with Regulatory Guide 1.97 requirements; 8510310211 851025 PDR ADOCK 05000271 F
PDR llt
b:
s-VERMONT YANKEE NUCLEAR POWER CORPORATION U.S. Nuclear Regulatory Commission October 25, 1985 Page 2 4
2.
equipment where range and environmental qualification or other attri-butes have been determined on a plant-specific basis to be appropriate for Vermont Yankee (VY); and 3.
equipment which must be modified or upgraded in order to provide ade-quate range, environmental qualification or other characteristics.
In that submittal, we stated that the appropriate category of environmental qualification was determined by utilizing the plant-specific analyses developed during our review of plant systems and equipment for compliance with 10CFR50.49.
This was accomplished in order to insure that the environmental qualification of the instrumentation is appropriate to the function it monitors.
This approach insured integration between safety functions and monitoring instrumentation.
The EG&G Interim Report transmitted with your request for additional infor-nation,[ Reference d], concluded for those items involving deviations or excep-tions to Regulatory Guide 1.97 recommended environmentally qualified instrumentation that, " Environmental qualification has been subsequently
. clarified by the environmental qualification rule, 10CFR50.49.
It is concluded that-the guidance of Regulatory Guide 1.97 has been superseded by a regulatory requirement. Any exception to this rule is beyond the scope of this review and should be addressed in accordance with 10CFR50.49."
The staff's Safety Evaluation addressing the environmental qualification of electric equipment at Vermont Yankee for compliance with the requirements of 10CFR50.49 [ Reference c)] stated, "With regard to Pteragraph (b)(3) of 10CFR50.49, the licensee evaluated existing system arrangements and identified equipment for the variables defined in Regulatory Guide 1.97, Revision 3.
A report outlining the results of the review,-schedules for modifications where necessary and-justification of deviations not requiring modifications has been i
submitted to the NRC for review. Since the report is still under review by the staff, some of the equipment identified in this report has not been added to the scope of.10CFR50.49. However, some of the equipment items jointly within the scope of.NUREG 0737 and Regulatory Guide 1.97 have been included in the 10CFR50.49 scope. When the Regulatory Guide 1.97 report and equipment lists contained therein have been finalized and accepted by the staff, appropriate equipment not already in the 10CFR50.49 will be added in accordance with the Regulatory Guide 1.97 Implementation Schedule."
This statement is. consistent with the understanding reached by NRC's
-Instrumentation and Control Systems Branch and the Nuclear Utility Group on Equipment Qualification, that for individual plants, a final decision on the scope of environmental qualification for post-accident monitoring equipment would be made during the Regulatory Guide 1.97 resolution process. Licensees i
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-October 25, 1985 Page 3 and applicants could take exception to the environmental qualification' aspect of Regulatory Guide 1.97 for specific instrumentation without filing a request for' exemption from Section 50.49.
However, they must furnish the staff an engi-neering justification explaining why environmental qualification is not warranted for the instrumentation in question. The technical staff would then review the exceptions taken to the environmental qualification aspect of-j
- Regulatory Guide 1.97 to determine whether or not qualification is warranted.
We took exactly this approach in our October 30, 1984 submittal. However, in the preliminary staff review from your contractor, EG&G, separated the Regulatory Guide 1.97 conformance review from the requirements for environmental qualification of equipment.
In several cases, Vermont Yankee determined that 4
the environmental qualification guidance contained in Regulatory Guide 1.97 was not compatible with the requirements determined in our plant-specific environ-mental qualification program.
In our. earlier submittal [ Reference b)], we iden-
[
tified and provided justification for those parameters where our plant-specific environmental qualification requirements were different from the guidance in Regulatory Guide 1.97.
We believe that-the integration between our Regulatory Guide 1.97 commitments and environmental qualification program justifies modifi-cation of the Design and Qualification Criteria Category for certain parameters.
Therefore, based on the additional information presented in response to your request, we are hopeful that the staff can now conclude that Vermont Yankee has F
complied with the requirements delineated.in NUREG 0737, Supplement No. 1, con-cerning Regulatory Guide 1.97.
l Because we are required by your Confirmatory Order of August 29, 1985
[ Reference e)] to implement (install or upgrade) Regulatory Guide 1.97 require-ments prior to startup for Cycle 13 (approximately Summer 1987) and we are pre-sently implementing all Environmental Qualification - Regulatory Guide i
1.97-related upgrades during our present outage, we request that your review and approval of Vermont Yankee's compliance with Regulatory Guide 1.97 be completed
.in a timely manner so as not to adversely impact our scheduled upgrades.
We trust that you will find this information satisfactory; however, should-you have any questions, please contact us.
Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION Warren P. Murph'y Vice President an Manager of Operations
ATTACHMENT A OPEN ITEMS FROM EG&G INCORPORATED REVIEW OF VERMONT YANKEE'S 0737, SUPPLEMENT 1 REGULATORY GUIDE 1.97 SUBMITTAL EG&G Comment No. 1 Reactor Vessel Level Reference Leg Area Temperature -
Redundancy should be provided for this Type A variable (Section 3.2).
I VERMONT YANKEE RESPONSE As further discussed in Attachment B, Item 3, Vermont Yankee's subsequent development of symptom-based emergency procedures has resulted in the Reactor Vessel Level Reference Leg Area Temperature thermocouples no longer falling within the definition of a Type A variable. As these instruments are no longer considered to be Type A variables, no redundancy is required.
1 EG&G Comment No. 2
. Torus Pressure - Redundancy should be provided for this Type A variable; environmental qualification should be addressed in accordance with 10CFR50.49 (Section 3.2).
VERMONT YANKEE RESPONSE We will provide both redundancy and environmental qualification for the Torus Pressure Monitoring System. This upgrade will be installed during the 1985-86 refueling outage.
EG&G Comment No. 3 Torus Air Temperature - Redundancy should be provided for this Type A variable; environmental qualification should be addressed in accordance with 10CFR50.49 (Section 3.2).
VERMONT YANKEE RESPONSE We will provide redundancy and environmental qualification of the Torus Air Space Temperature Monitoring System. This modification will be installed during the 1985-86 refueling outage.
EG&G Comment No. 4 Neutron Flux - The licensee's present instrumentation is acceptable on the interim basis until Category 1 instrumentation is developed and installed (Section i
3.3.1).
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Attachment A Page 2 of 5 VERMONT YANKEE RESPONSE Based upon the analysis conducted in developing our program for. compliance with 10CFR50.49, we have concluded that indication of Neutron Flux down to 1%
power is sufficient to determine that a successful scram has occurred. This indication is adequate for all accident conditions identified in the environmen-tal qualification rule. We have prepared a design change to insure the environ-mental qualification of the Local Power Range Monitor (LPRM), which provides this indication.
It should be noted that Vermont Yankee's shutdown analysis for environmental qualification does not, at any time, include the use of boron injection to achieve a safe shutdown condition. Once a successful control rod scram has been verified, an inadvertent reactivity addition is not possible.
Regulatory requirements do not require consideration of failure to scram (ATWS) events coincident with a design basis accident..Therefore, the currently installed Intermediate Range Monitors and Souce Range Monitors will not be sub-jected to harsh environmental conditions during these events. Therefore, we conclude that Vermont Yankee's Neutron Flux Monitoring System will be in full compliance with the regulatory requirements of.10CFR50.49 upon completion of the LPRM upgrade and should not be considered interin in assessing compliance with NUREG 0737, Supplement 1.
It is our intention to complete this modification during the 1985-86 refueling outage.
However, completion of this effort is con-
~ tingent upon our acceptance of the cable purchased to accomplish the modifica-tion. The manufacturer has been notified that portions of the cable received thus far indicate potential defects and we are aggressively pursuing this issue with them..
EG&G Comment No. 5 Reactor Core Isolation Cooling Flow - Environmental qualification should be addressed in accordance with 10CFR50.49 (Section 3.3.5).
VERMONT YANKEE RESPONSE As explained in the Vermont Yankee Equipment Qualification Program, the equipment utilized to monitor reactor core isolation cooling flow does not experience harsh environmental conditions during the small break LOCA event for which it is relied upon. Therefore, we conclude that the reactor core isolation cooling flow instrumentation is in full compliance with the requirements of 10CFR50.49 and is consistent with the recommendations in Regulatory Guide 1.97.
EG&G Comment No. 6 High Pressure Coolant Injection Flow - Environmental qualification should be addressed in accordance with 10CFR50.49 (Section 3.3.6).
VERMONT YANKEE RESPONSE j
As explained in the Vermont Yankee Equipment Qualification Program, the s
equipment utilized to monitor high pressure coolant injection flow does not i
experience harsh environmental conditions during the small break LOCA event for which it is relied upon. Therefore, we conclude that the high pressure coolant injection flow is in full compliance with the requirements of 10CFR50.49 and is consistent with the recommendations in Regulatory Guide 1.97.
Attachment A Page 3 of 5 EG&G Comment No. 7 Core Spray System Flow - Environmental qualification should be addressed in accordance with 10CFR50.49 VERMONT YANKEE RESPONSE The safe shutdown analysis conducted as part of the Vermont Yankee
' Equipment Qualification Program concludes that environmentally qualified core spray flow indication is not required since various qualified primary and con-tainmer.t system monitors provide the ultimate indication of ECCS System perfor-marce.
In addition, core spray valve position information, along with pump otor running current,. indicates the mode of system operation and is far more s
valuable than flow indication. Therefore, we conclude that Core Spray Flow Indication should properly be treated as a Category 3 variable for Vermont Yankee. Based upon our understanding of the agreement between the Equipment
- Qualification Group and the NRC, this does not constitute an exception to 10CFR50.49 and should be addressed in the resolution of Regulatory Guide 1.97 issues.
ES&G Comment No. 8 Standby Liquid Control System - The licensee should justify the use of pump discharge pressure instrumen-tation for this application (Section 3.3.7).
VERMONT YANKEE RESPONSE As a result of the analyses condt:cted relative to the compliance with 10CFR50.49, we have concluded the Star.dby Liquid Control System (SLCS) is not required in the mitigation of any. accident. Therefore, at this time, we do not consider.SLCS flow to be a post-accident monitor. We feel that it is adequate to monitor pump discharge pressure since this will provide adequate assurance of
-proper system operation. This issue should be considered closed relative to compliance with Regulatory Guide 1.97; however, we recognize that it may receive additional consideration in resolution of the anticipated transient without
- scram issue.
EG&G Comment.No. 9 RHR Heat Exchanger Outlet Temperature - The licensee should justify deviation in range; environmental quali-fication should be addressed in accordance with 10CFR50.49 (Section 3.3.8).
' VERMONT YANKEE RESPONSE For Vermont Yankee, the RHR heat exchanger outlet temperature param'ter e
referred to herein is the RHR System side (shell side). As stated in the Vermont Yankee Environmental Qualification Program, monitoring the RHR heat exchanger shell side outlet temperature is not relied upon to achieve a safe shutdown. The function of the RHR beat exhcnagers post-accident is to remove stored and decayed heat.
Monitoring the reactor and primary containment respon-ses (i.e., torus water temperature, drywell and reactor pressure) provides the most direct indication of the effectiveness of the RHR System. Therefore, we
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Attachment A Page 4 of 5 conclude that RHR heat exchange outlet temperature should be classified as a
. Category.3 variable for Vermont Yankee. Based upon our understanding of the agreement between the Equipment Qualification Group and the NRC, this does not constitute an exception to 10CFR50.49 and should be addressed in the resolution of Regulatory Guide 1.97 issues. For the post-accident modes of.the RHR System
.(LPCI and' containment cooling), the source of water is from the torus. The maximum torus water temperature during design basis accidents is well below
-. 300*F.
Therefore, under these conditions, the installed range is deemed ade-quate.
EG&G Comment No. 10 Cooling Water Temperature to ESF System Components -
The licensee should justify the deviation in range; environmental qualification should be in accordance with ICCFR50.49 (Section 3.3.9).
VERMONT YANKEE RESPONSE i
We have determined in the Vermont Yankee Environmental Qualification Program that the monitoring of cooling water temperature to ESF System com-
-ponents will not aid in the. accomplishment of any required safety function. On that basis, th.erefore, it is our position that this indication constitutes a
" nice to have" monitor and that it should properly be identified as Category 3 for Vermont Yankee. Based upon our understanding of the agreement between the i'
. Equipment Qualification Group and the NRC, this does not constitute an exception to 10CFR50.49 and should be addressed in the re^Tsotion of Regulatory Guide 1.97 issues.
In addition, we have determined that e.n m
,og the service water outlet from the RHR heat exchanger provides a worst-case monitor for this parameter.
During design basis accident service, the RHR service water outlet design
' temperature is 150'F; under these conditions, the installed range of 0-150*F is deemed adequate.
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EG&G Comment No. 11
' Cooling Water Flow to ESF System Components - The l
licensee should justify the use of pump discharge pressure instrumentation for this application; environ-mental qualification should be addressed in-accordance with 10CFR50.49'(Section 3.3.10).
_ VERMONT YANKEE RESPONSE For Vermont Yankee, Cooling Water Flow to ESF System Components is
. interpreted to be the RHR Service Water Flow. As discussed above, the Vermont Yankee Environmental Qualification Program has concluded that cooling water flow to ESF system components.need not be monitored to assure accomplishment of a
. safe shutdown following a design basis accident. We believe that monitoring
Attachment A Page 5 of 5 the reactor and primary containment responses provides the best indication of accomplishment of safety functions, and thereby, determines the effectiveness of safety systems, and therefore, constitutes a " nice to have" monitor, which should be properly identified as Category 3 for Vermont Yankee. Based upon the
" nice to have" categorization of this parameter and its intended function, to ensure operation, we have determined that pump discharge pressure is an accep-table indication.
Based upon our understanding of the agrement between the Equipment-Qualification Group and the NRC, this does not constitute an exception to 10CFR50.49 and should be addressed in the resolution of R9gulatory Guide 1.97 issues.-
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ce ATTACHMENT B VERMONT YANKEE REGULATORY GUIDE 1.97 REPORT ITEMS REQUIRING CLARIFICATION OR CORRECTION (Submitted October 30, 1984)
ITEM 1:
TORUS AIRSPACE TEMPERATURE MONITORS Ir. the process of completing our design change package to upgrade torus airspace temperature monitors to comply with one of our Regulatory Guide 1.97 commitments, we have identified a Human Factors Engineering concern related to the control. board indicator associated with this parameter. Our original com-mitment stated an indicated range of 0-300'F; however, to provide increased resolution on the indicator, we have reduced the indicator range to 50-300*F.
Since the torus is totally contained in a heated building, we conclude that this reduction on the lower end of the insrument range will not adversely affect the plant operations.
ITEM 2:
ACCIDENT SAMPLING - pH Under Regulatory Guide 1.97, Revision 3, Type E variables for accident sampling capability (analysis capability on-site) for primary coolant and sump, pH is identified as a Category 3 variable to be grab sampled in the 1-13 range for release assessment, verification and analysis purposes, Vermont Yankee's Regulatory Guide 1.97 Report Instrumentation Matrix,.under accident sampling Item E17 (primary coolant sample), incorrectly, identified pH as a measured variable.
. Vermont Yankee previously notified the NRC in our letter of September 21, 1984, concerning NUREG 0737, Item II.B.3, Post-Accident Sampling Capability, Criterion 10, that "...pH measurements are not included because an undiluted sample cannot be obtained from the post-accident sample panel." By letter dated January 14, 1985, the NRC issued a Safety Evaluation Report which accepted Vermont Yankee's provisions to meet Criterion 10 of Item II.B.3 in NUREG 0737.
Although the SER's statement indicated that'the accuracy, range and sensitivity of.the PASS instruments were consistent with the recommendations of Regulatory Guide 1.97 and the clarification of NUREG 0737, Item II.B.3; the SER's discussion under Criterion 2 stated, "The minimum and maximum dilution reactor coolant samples coming from the PASS is 100:1 and 1800:1, respectively."
Therefore, thic statement identifies that the NRC understood that undiluted samples could not be obtained from the PASS panel. The NRC's Post-Implementation Audit Report (dated August 17, 1984) recommended that VY make provisions for determining the pH of samples as a consideration for im-provement of the system.
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Attachment B Page 2 of 2 Vermont Yankee subsequently evaluated the value of pH measurements derived from a diluted post-accident sample and the ability of the diluted sample to-characterize the pH of the original sample. As test specimens, Vermont Yankee utilized buffered pH solutions; one acidic and or.e caustic. These solutions were diluted by 1000:1 and tested for pH.
This dilution, as a minimum, is appropriate to maintain personnel radiation exposures ALARA for the expected post-accident coolant activity levels. Vermont Yankee measured the pH of the resulting diluted sample and concluded that such measurements could not specifi-cally quantify the pH of the coolant. At most, for those situations where the coolant is either highly acidic or highly alkaline, all that can be inferred
~from such measurements is whether the undiluted coolant sample is acidic or alkaline.
In addition, Vermont Yankee evaluated the need to measure coolant pH at a fresh water BWR site and determined that coolant pH is not particularly important because all metals which contact the coolant are compatible with liquids having a wide range of pH.
Only the combination of high chloride con-centration and low pH would cause concern.
It is highly unlikely that such a condition would exist after a core damage accident because chloride intrusion is not expected at a fresh water site, coolant pH would not be compromised by contact with any component in the drywell or torus and the cooling provided by post-accident heat removal systems reduces the corrosion potential (cool water is less corrosive at all pH values than hot water). Thus, we conclude that relatively little meaningful information would be gained from post-accident coolant pH sampling for Vermont Yankee.
Therefore, based on Vermont Yankee's prior notification to the NRC stating that undiluted pH. samples cannot be obtained for the post-accident sample sta-tion; the NRC's acceptance of Vermont Yankee's provisions to meet NUREG 0737, Item II.B.3, Criterion 10; and Vermont Yankee's evaluation of diluted pH samples',
discussed above, we request acceptance of our deviation from the Regulatory Guide 1.97 requirement and removal of pH as a primary coolant sample variable on our. Regulatory Guide 1.97 Instrumentation Matrix.
ITEM 3:
REACTOR VESSEL LEVEL REFERENCE LEG AREA TEMPERATURE As indicated in Reference d), Vermont Yankee's review for plant-specific Type A variables was performed utilizing the draft symptom-based emergency pro--
cedures currently under development. Reactor Vessel Level Reference Leg Area Temperature thermocouples were referenced in these draft emergency procedures, and were therefore classified as a Type A variable.
Subsequent development of Vermont Yankee's symptom-based emergency proce-dures has resulted in the Reactor Vessel Level Reference Leg Area Temperature theroecouples being deleted from the final version of the emergency procedures.
Accordingly,-these instruments no longer meet the definition of a Type A
- variable, i.e., primary information utilized to perform specified manually controlled actions...that are required for safety systems to accomplish their safety functions for-design basis events, and should be removed from the Type A variable list for Vermont Yankee.