ML20211E790
| ML20211E790 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 09/15/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20211E780 | List: |
| References | |
| NUDOCS 9709300264 | |
| Download: ML20211E790 (9) | |
Text
-_
- *tos, lt UNITED STATES
,y *-
}
NUCLEAR REGULATORY COMMISSION
- g f
w Assiwarow, o.c. somewooi
%...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS.130 AND 122 TO FACILITY OPERATING LICENSE NOS DPR 42 AND DPR-60 NORTHERN STATES POWER COMPANY PRAIRIE ISLAND NUCLEAR GENERATING PLANT. UNIT NOS.1 AND 2 DOCKET NOS. 50 282 AND 50-306
1.0 INTRODUCTION
By letter dated May 7,1997, as supplemented May 30, July 29, and September 12,1997, the Northem States Power Company (NSP or the licensee) requested amendments to the Technical Specifications (TS) appended to Facility Operating License Nos. DPR 42 and DPR 60 for the Prairie Island Nuclear Generating Plant, Unit Nos.1 and 2. The proposed amendments would revise Technical Specifications (TS) 3.8," Refueling and Fuel Handling."
The July 29 and September 12,1997, supplements provided clarifying information within the scope of the original application and did not change the staff's initial proposed no significant hazards considerations determination (62 FR 35850).
On July 17,1997, the licensee also submitted revisions to two bases pages related to the spent fuel pool personnel access doors. These revisions are also included in this safety evaluation.
2.0 BACKGROUND
The licensee's submittal stated that the proposed amendments would maintain limitations on spent fuel handling relating to spent fuel pool special ventilation system (SFPSVS) operability Limitations on crane operations in the spent fuel pool enclosure relating to SFPSVS operability would be removed from the TS. These changes are necessary to allow movement of loads over spent fuel stored in the spent fuel pool enclosure with the SFPSVS inoperable. The SFPSVS is designad to provide ventilation of the spent fuel pool enclosure in the event that high radiation is detected. This is a safeguards system with two complete 100 percent capacity trains, each capable of meeting the design requirements.
The licensee also stated that this license amendment request proposes to revise Prairie Island TS 3.8.D., which prescribes the limiting conditions for operability for the SFPSVS.
Current TS 3.8.D.3 states: "With both trains of the Spent Fuel Pool Special Ventilation System inoperalle, suspend all fuel handling operations....' Compliance with this specification as written could preclude movement of any loads, including new fuel, into the spent fuel pool enclosure. The proposed license amendments would remedy this situation by 9709300264 9709tS PDR ADOCK 05000282 P
PDR 33-
2 specifying SFPSVS operability only during movement of inadiated fuel. It would also eliminate confusion with respect to the applicability of this specification by removing crane operating limitations and conforming it to the guidance of NUREG 1431, ' Standard Technical Specifications, Westinghouse Plants / the improved Standard Technical Specifications.
In its letter dated May 7,1997, the licensee provided a commitment stating that ' Prairie Island will assure that heavy loads do not present a potential for damaging irradiated fuel through use of.1) a single failure proof-crane with -igging and procedures which implement Prairie Island commitments to NUREG 0612; or,2) spent fuel pool covers and their implementing plant procedures."
In 1992 NSP received approval to handle spent fuel storage casks in Spent Fuel Pool 1 while it contains irradiated fuel. In support of that approval, NSP installed a single failure-proof auxiliary building crane which meets the design criteria of NUREG-0612, ' Control of Heavy Loads at Nuclear Power Plants." Prairie Island has also upgraded the west hoist on the spent fuel pool bridge crane to meet the design criteria of NUREG-0612.
3.0 EVALUATION The spent fuel pool enclosure is a Class I reinforced concrete structure and is located between the contalnments for Prairie Island Units 1 and 2. The fuel pool enclosure covers the new fuel pit and both spent fuel storage pools and a spent fuel handling crane, and is completely contained within the auxiliary building. The large overhead auxiliary building crane passes over the spent fuel pool enclosure. At the four comers of the enclosure are personnel access doors. On one side is a third, large single door opening that is used to transfer new fuelinto the enclosure for storage in the new fuel pit. At approximately the center of the enclosure, on either side, are two full height double-doored openings that serve as access for large equipment such as casks. In between the double-doored openings there is a roof slot with movable panels. The double doored openings and roof slot with movable panels facilitate the handling of large equipment by the auxiliary building crane through the enclosure. In order to move loads into the spent fuel pool enclosure or into the auxiliary building central court area through the spent fuel pool enclosure, the enclosure roof slot doors and the large north and south access doors are required to be opened. Therefore, when loads are handled by the auxiliary building crane in the spent fuel pool enclosure, both trains of the spent fuel pool special ventilation system are inoperable.
The SFPSVS consists of two independent,100 percent capacity trains, each capable of meeting the design requirements. One train takes suction from the spent fuel pool enclosure and is filtered by the Unit 1 containment inservice purge system. The other train also takes suction from the spent fuel pool enclosure and is filtered by the Unit 2 containment inservice purge system. The minimum flow requirement of SFPSVS is sized to maintain a negative pressure in the spent fuel pool enclosure and provides ventilation in the event that high radiation is detected.
The comotetely enclosed spent fuel pool area is normally ventilated and exhausted through the normal ventilation system which includes roughing and high efficiency particulate absolute (HEPA) filters in the event of high radiation in the pool area, signals from radiation monitors in the normal ventilation exhaust duct isolate and shut down the normal ventilation system l
,o we -
3-and initiate the SFPSVS. The SFPSVS shares the exhaust portion of the containment inservice purge system. The air flow is then directed through redundant roughing, HEPA, and charcoal filters in this syr, tem. The licensee has determined through testing that when any doors into the spent fuel pool enclosure are opened, the spent fuel pool special i
ventilation system is unable to develop a negative pressure within the enclosure and j
therefore, both trains of the spent fuel pool special ventilation system are inoperable.
Proposed License Conditions:
In its submittal dated September 12,1997, the licensee prcposed the following license condition:
Prairie Island will assure that heavy loads do not present a potential for damaging irradiated fuel through use of 1) a single failure proof crane with rigging and procedures which implement Prairie Island commitments to NUREG-0612; or 2) spent fuel pool covers with their implementing plant procedures for installation and use.
The Prairie Island spent fuel pool cover is comprised of three cover sections. These cover sections may be used individually as work platforms over the spent fuel pools or new fuel pit.
The cover sections may also be fastened together and used as a protective barrier for handling heavy loads. NSP has evaluated the consequences of dropping one end of a cover section and concluded that, since both ends of the cover sections are required to extend over the pool deck by a minimum of 8 inches and the cover is lifted a maximum of 6 inches above the pool deck, if a failure of the hoist or rigging on one end of a cover section caused the cover section to drop, this physical geometry prevents the dropped end from falling into the spent fuel pool. Thus, NSP concluded that the cover sections can be handled in a safe manner which assures that the cover sections do not fall into a spent fuel pool.
The staff agrees with the licensee's assessment of a hoist or rigging failure while lifting a spent fuel pool cover and that it will not cause the cover to drop into the pool. Therefore, the use of spent fuel pool covers will provide adequate protection against heavy loads damaging irradiated fuel. And the procedures by which the covers (a heavy load themselves) are lifted will not present a potential for damaging irradiated fuel.
The staff agrees with the licensee's proposed license condition.
The proposed changes to TS 3.8, Refueling and Fuel Handling, and justifications thereof are described below:
Current TS 3.8 REFUELING AND FUEL HANDLING:
Aoolicability Applies to operating limitations associated with fuel-handling operations, CORE ALTERATIONS, and crane operations in the spent fuel pool enclosure.
^ ~~~ ~ T
~~~~~~~
4 l
Obiectives To ensure that no incident could occur ouring fuel handling, CORE ALTERATIONS and crane operations that would affect public health and safety.
Proposed TS 3.8 REFUELING AND FUEL HANDLING:
Aoolicability Applies to operating limitations associated with fuel handling operations and CORE ALTERATIONS.
Obiectives To ensure that no incident could occur during fuel handling and CORE ALTERATIONS that would affect public health and safety.
Justifications:
The licensee provided the rationale for the proposed change as follows:
a.
Prairie Island has other cranes that are capable of handling heavy loads in the vicinity of safeguards equipment or irradiated fuel. The other cranes, as proposed, are not part of the TS 3.8 but are controlled through commitment to NUREG-0612 and corresponding plant procedures as controlled in accordance with 10 CFR 50.59 review.
b.
The auxiliary building crane and spent fuel pool bridge crane west hoist have been modified to meet NUREG-0612 guidance for single-failure-proof-cranes.
c.
Spent fuel pool protective covers may be installed prior to handling heavy loads, up to the protective cover design limits of 24,800 pounds, to prevent loads from dropping into the spent fuel pool as controlled by plant procedures. The plant procedures call for (1) protective covers for the crane handling loads up to the design limit or use of a single failure proof crane, and (2) loads in excess of design limit, use of the single-failure proof auxiliary building crane.
Based upon the above, the licensee concluded that the crane operations in the fuel pool enclosure are safe because heavy loads are handled by cranes, rigging, and procedures that implement the commitments of NUREG-0612 or protective covers. NUREG-0612 presents an overall philosophy that provides a debte in-depth approach for controlling the handling of heavy loads. The approach is directed to primtino load drops. If a licensee complies with the guidance in NUREG-0612, through use of a single-tailure proof crane or associated rigging and procedures, further action is not needed to reduce the risks associated with the handling of heavy loads. This includes the performance of a load drop analysis. If a crane meets the single failure-proof criteria of NUREG-0554, " Single Failure Proof Cranes," the load is not postulated to drop and, therefore, any load drop consequences would not be required y
_,-o,,rw w-,--
,-y-
5-to be mitigated. The licensee stated in its May 7 and July 29 submittals that it meets single fallure-proof criteria.
The staff agrees with the licensee's proposed change to crane operations; therefore, the proposed change is acceptable.
Current TS 3.8.D.1 Spent Fuel Pool Special Ventilation System Both trains of the Spent Fuel Pool Special Ventilation System shall be OPERABLE at all times (except as specified in 3.8.D.2 and 3.8.D.3 below).
Proposed TS 3.8.D.1 Spent Fuel Pool Special Ventilation System Both trains of the Spent Fuel Pool Special Ventilation System shall be OPERABLE during movement of irradiated fuel assemblies in the spent fuel pool enclosure (except as specified in 3.8.D.2 and 3.8.D.3 below).
Justifications:
The licensee's rationale for the proposed change is as follows:
a.
The proposed change will require the SFPSVS to be operable only when irradiated fuel assemblies are rnoved within the spent fuel pool enclosure to maintain the plant within the design basis assumptions. SFPSVS operability is not required when the I
auxiliary building crane is used to move loads into the spent fuel pool enclosure due to the need to open the enclosure roof slot doors, b.
The Prairie Island design-basis fuel handling accident analyses, which assume that all fuel rods in one fuel assembly fait due to the drop of one fuel assembly directly onto another fuel assembly, take credit for operation of the SFPSVS.
c.
The movement of heavy loads within the spent fuel pool enclosure is govemed by the Prairie Island updated safety analysis report (USAR), Northem States Power (NSP) commitments to NUREG-0612, and plant implementing procedures in combination with physical upgrades of the auxiliary building crane snd spent fuel pool bridge crane west hoist to assure that radiological releases due to load movements will not occur.
Therefore, SFPSVS operability at all times is inconsistent with the system design.
The staff agrees with the licensee's proposed changes as related to the operability of SFPSVS and crane operations; therefore, the proposed change is acceptable. NUREG 0612 presents an overall philosophy that provides a defense-in-depth approach for controlling the handling of heavy loads. The approach is directed to preventing load drops. If a licensee complies with the requirements of NUREG-0612, through use of a single failu;e-proof crane or associated rigging and procedures, further action is not required to reduce the risks associated with the handling of heavy loads.
6-Current TS 3.8.D.2 Spent Fuel Pool Special Ventilation System With one train of the Spent Fuel Pool Special Ventilation System inoperable, fuel handling ~
i operations and crane operations with loads over spent fuel (inside the spent fuel pool enclosure) are permissible during the following 7 days, provided the redundant train is demonstrated OPERABLE prior to proceeding with those operations.
Proposed TS 3.8.D.2 Spent Fuel Pool Special Ventilation System if one train of the Spent Fuel Poo! Special Ventilation System is inoperable during movement of irradiated fuel assemblies in the spent fuel pool enclosure, restore the train to OPERABLE status within 7 days. If the inoperable train is not restored within 7 days, place the OPERABLE Spent Fuel Pool Special Ventilation System in operation or suspend movement of irradiated fuel assemblies in the spent fuel pool enclosure.
Justifications:
The licensee provided the following rationale as justification for the proposed change:
s.
The proposed change provides an approach consisteni with the current TS such that if one train of the spent fuel pool special ventilation system is inoperable the proposed TS would allow movement of irradiated fuel to continue for 7 days, b.
This 7-day completion time is backed up by a fully redundant SFPSVS train and is
(
acceptable d"e to the low probability of a fuel handling accident during this period.
An attemative to placing the redundant SFPSVS train in service is to suspend movement of irradiated fuel assemblies, which precludes a fuel handling accident.
c.
The deletion of crane operations is justified by use of spent fuel pool protective covers to prevent load drops from falling into the spent fuel pool, or use of cranes upgraded to NUREG-0612 single-f. allure-proof specifications assures that the potential for a load drop is extremely small.
d.
The demonstration of operability of the redundant train prior to resumption of fuel handling operations is justified due to (1) a low probability of a fuel handling accident during a 7-day period (2) a low probability of the redundant SFPSVS train failure since each train is operpted monthly, and (3) each SFPSVS train, within 30 days prior to handling irradiated fuel, is actuated by a test radiation source, e.
The proposed TS that allows for the continuous operation of the operable SFPSVS train is justified beyond 7 d&ys without restoration of the inoperable train based upon:
(1) Such an occurrence is unlikely and NSP does not intend to operate without safeguards trains operable, and (2) SFPSVS capability through the requirements of current TS 4.14 and invoking the TS.4.15.B.1 provision, which would require the SFPSVS to be inoperable to allow required surveillance testing to be performed after 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of operation.
1 7
The NRC staff does not agree with the licensee's claim that the proposed change provides an approach consistent wF.h the current TS such that if one train of spent fuel pool special ventilation system is inoperable the proposed TS would allow movement of irradiated fuel to continue for 7 days. With one train of SFPSVS inoperable, the current TS does permit fuel handling operations and crane operations with loads over spent fuel (inside the spent fuel pool enclosure) for 7 days, but it also requires the redundant train to be demonstrated OPERABLE prior to proceeding with inese operations. The propoced change to TS 3.8.D.2 is largely based upon a probabilistic argument that has not been quantified by the licensee.
The staff believes that it does not meet the intent of the current TS, in that it allows one train to be inoperable for an indefinite period, thereby reducing the existing margin of safety.
1 Therefore, this proposed change is denied.
Current TS 3.8.D,3 Spent Fuel Pool Special Ventilation System With both trains of the Spent Fuel Pool Special Ventilation System inoperable, suspend all fuel handling operations and crane operations with loads over spent fuel (inside the spent fuel pool enclosure).
Proposed TS 3.8.D.3 Spent Fuel Pool Special Ventilation System With both trains of the Spent Fuel Pool Special Ventilation System inoperable, suspend movement of irradiated fuel ast.emblies in the spent fuel pool enclosure.
Just'fications:
The licensee stated that the rationale for the proposed change is similar to the rationale provided for the TS 3.8.D.2 The staff has determined that the rationale for permitting the proposed change is similar to the rationale provided in the justification for the proposed TS 3.8.D.1.
Proposed TS 3.8.D.1 (a) states that the proposed change will require the SFPSVS to be operable only when irradiated fuel assemblies are moved within the spent fuel pool enclosure to maintain the plant within the design basis assumptions. SPFSVS operability is not required when the auxiliary building crane is used to move loads into the spent fuel pool enclosure due to the need to open the enclosure roof slot doors; (b) states that the Prairie Island design-basis fuel handling accident analyses, which assume that all fuel rods in one fuel assembly fail due to the drop of one fuel assembly directly onto another fuel assembly, take credit for operation of the SFPSVS; and (c) states that the movement of heavy loads within the spent fuel pool enclosure is govenied by the Prairie Island USAR, NSP commitments to NUREG-0612, and plant implementing procedures in combination with physical upgrades of the auxiliary building crane and sper.t fuel pool bridge crane west hoist to assare that radiological releases due to load movements will not occur. Thus, SFPSVS operability at all times is inconsistent with the system design.
The staff agrees with the licensee's proposed change for the operability of SFPSVS and crane operations and accepts the proposed change.
l
. Current TS 3.8 Bases REFUELING AND FUEL HANDLING The Spent Fuel Pool Special Ventilation System (Reference 3) is a safeguards system which maintains a negative pressure in the spent fuel enclosure upon detection of high area radiation. The Spent Fuel Pool Normal Ventilation System is automatically isolated and exhaust air is drawn through filter modules containing a roughing filter, particulate filter, and a charcoal filter before discharge to the environment via one of the Shield Building exhaust stacks. Two completely redundant trains are provided. The exhaust fan and filter of each train are shared with the corresponding train of the Containment In service Purge System.
High efficiency particulate absolute (HEPA) filters are installed before the charcoal adsorbers to prevent clogging of the iodine adsorbers in each SFPSVS filter train. The charcoal adsorbers are installed to reduce the potential release of radiolodine to the environment.
Proposed TS 3.8 Bases REFUELING AND FUEL HANDLING The Spent Fuel Pool Special Ventilation System (SFPSVS) (Reference 3) is a safeguards system which maintains a negative pressure in the spent fuel enclosure upon detection of high area radiation. The Spent Fuel Pool Normal Ventilation System is automatically isolated and exhaust air is drawn through filter modules containing a roughing filter, particulate filter, and a charcoal filter before discharge to the environment via one of the Shield Building exhaust stacks. Two completely redundant trains are provided. The exhaust fan and filter of each train are shared with the corresponding train of the Containment in service Purge System. High efficiency particulate absolute (HEPA) filters are installed before the charcoal adsorbers to prevent clogging of the lodine adsorberc in each SFPSVS filter train. The charcoal adsorbers are installed to reduce the potential release of radiolodine to the environment. Doors to the spent fuel pool enclosure are required to be maintained closed when SFPSVS OPERABILITY is required. Opening of personnel doors for personnel use is acceptable (blocking a door open is not allowed).
Justifications:
The licent.ee's rationale for the proposed change is as follows:
a.
The licensee determined through testing that the SFPSVS is unable to develop a negative pressure in the spent fuel pool enclosure when doors into the enclosure are
. open. Thus, the doors into the spent fuel pool enclosure must be closed as a condition for spent fuel pool special ventilation system operability, b.
Opening of personnel doors for personnel use is acceptable, since the system will readily establish a negative pressure following spring closure of the door if an event occurs and the system is required to be opera *ule. As stated in the proposed Bases, blocking of doors open is not permitted.
The staff agrees with the licensee's proposed changes for the operability of SFPSVS in Nation to securing of the spent fuel pooi enclosure doors. Therefore, the staff finds acceptable the proposed change to the Bases of TS 3.8. The proposed chang 2 will add
" Doors to the spent fuel pool enclosure are required to be maintained closed when SFPSVS
9 OPERABILITY is required. Opening of personnel doors for personnel use is acceptable (blocking a door is not allowed).'
By letter dated July 17,1997, the licensee submitted two changes to the Prairie Island TS Bases related to the spent fuel pool personnel access doors. One change is addressed above; the other added a reference. The staff finds the addition of the reference acceptable and has enclosed the revised Bases page B.3.8 5.
4.0 STATE CONSULTATIQN in accordance with the Commission's regulations, the Minnesota State official was notified of the proposed issuance of the emendments. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requiren,ent with respect to installation or use of a facilit/
component located within the restricted area as defined in 10 CFR Part 20. The NF.C staff has determined that the amendments involve no significant increase in the amount 4, and no significant change in the types, of any effluents that may be released of' site, and (Tat there is no significant increase in individual or cumulative occupational radiation exposure. Tha Commission has previously issued a proposed finding that the amendments involvs no significant hazards consideration and there has been no public comment on such fading (62 FR 35850). Accordingly, the amendments meet the eligibility criteria for categoncel exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmerital impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor. J. Raval Date: September 15, 1997
_ _ _. _ _ _ _ _ _. _ _